Dept of Physiology

DEPT OF PHYSIOLOGY

Researcher : Ballard HJ

Project Title:	The signal transduction pathway linking pH depression to ATP efflux from muscle cells
Investigator(s):	Ballard HJ
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	10/2007

Abstract:

My previous study has demonstrated that pH depression triggers the release of ATP from skeletal muscle cells: this ATP is broken down in the interstitial space to adenosine, which mediates vasodilation. Hence, this pathway plays a major role in the matching of the blood supply to the oxygen demands of the tissue, in situations such as muscle contractions. I have further demonstrated, by the use of inhibitors to the various ATP-transport proteins that are expressed in muscle, that the ATP release takes place through an electrodiffusional pathway. Based on these studies, it is proposed that the ATP efflux occurs through the cystic fibrosis transmembrane conductance regulator (CFTR) The purpose of the proposed investigation is 1. To definitely confirm that CFTR is the transport molecule that is responsible for the ATP efflux during pH depression. (Pilot experiments using a specific inhibitor of CFTR indicate that this is the case) 2. To investigate the signal transduction mechanism that links the reduction in pH to the CFTR.

Project Title:	Cystic fibrosis transmembrane conductance regulator in ATP efflux from muscle cells
Investigator(s):	Ballard HJ
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	12/2008

Abstract:

Previous studies using blockers of the cystic fibrosis transmembrane conductance regulator (CFTR) have suggested that it mediates the efflux of ATP from muscle cells during acidosis. Such studies can be criticised on the grounds that the blockers may affect more than one transporter. In this project, I will use RNA interference to knock down the CFTR gene, and determine the effects of that on acidosis-stimulated ATP efflux. This will allow me to determine, with certainty, whether the ATP efflux is mediated by CFTR.

Project Title:	Interaction between K-ATP channel and CFTR in ATP efflux from muscle
Investigator(s):	Ballard HJ
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	10/2009

Abstract:

Our previous studies have shown that the cystic fibrosis transmembrane conductance regulator (CFTR) plays an obligatory role in the acidosis-induced efflux of ATP from skeletal muscle. Some authors have proposed that ATP leaves cells through the CFTR chloride channel, whilst others believe that CFTR regulates the activity of another channel, through which ATP is conducted. We previously found that glibenclamide, a K-ATP channel blocker, inhibited the acidosis-induced ATP efflux. Under some circumstances, multiple channels can associate together in the membrane to form a large dynamic signalling complex. The main objective of this study is to determine whether CFTR and the K-ATP channel form such a signalling complex, and what role that complex plays in the efflux of ATP from muscle.

Researcher : Bourreau JP

Project Title:	Role of cyclooxygenase in the ventricular effects of adrenomedullin: does prostacyclin contribute towards the cardiodepression in the late hypodynamic phase of septic shock?
Investigator(s):	Bourreau JP
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2003

Abstract:

To measure the levels of PGI₂ by quantifying its stable hydrolysis product, 6-keto PGF_1[alpha] by EIA after stimulation with ADM and at various time-points corresponding to the biphasic inotropic effects of ADM, and to mesure the PGI₂ levels in our animal model of terminal septic shock; to observe the signal transduction pathway involved in the ventricular effects of ADM with respect to PGI₂.

Project Title:	Endothelim-dependent hyperpolarization and relaxation of vascular smooth muscle: influence of the mode of excitation-coupling of vasoconstrictors
Investigator(s):	Bourreau JP
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	02/2005

Abstract:

To test the hypothesis that expression of endothelium-dependent hyperpolarization-induced relaxation in a given vascular bed depends on the vasoconstrictor's coupling mode. We aim in the project at establishing controlled experimental conditions that will optimise the expression of endothelium-dependent hyperpolarization-induced relaxation and thus optimize the investigation of its mechanism(s).

Project Title:	Switch in G-protein coupling. Role of intracellular cAMP
Investigator(s):	Bourreau JP
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	01/2006

Abstract:

In our animal model of septic shock, we were able to identify the overproduction of the vasoactive peptide adrenomedullin as a key factor responsible for depression of ventricular function during the hypodynamic phase of shock (Am.J.Physiol., Heart Circ.Physiol. 286: H1034-H1042, 2004). Physiologically, this peptide is a positive inotropic substance that increases the force of contraction via a beta adrenergic-like effect; i.e., by raising the intracellular cAMP concentration. This triggers PKA-dependent phosphorylation of key protein targets (L-type calcium channels, phospholamban, TnC…), which results in positive inotropy and lusitropy. It was thus difficult to understand why a substance that, as often claimed in the litterature, should function to overcome situations where cardiac function is compromised (such as septic shock), failed to do so but rather contributed significantly to the progression of ventricular depression. We have also gathered data showing that the negative inotropic effect of adrenomedullin develops slowly and is dependent on the concomittent expression of the inducible form of cyclooxygenase, COX2 (Am J Physiol Heart Circ Physiol. 2004 Mar;286(3):H1034-42). Moreover, our recent findings (under revision, Am J.Physiol.) show clearly that this negative inotropic effect of adrenomedullin in the presence of COX 2 induction is pertussis toxin-sensitive, suggesting a switch in G-protein coupling from Gs to Gi. This negative inotropic effect of adrenomedullin is also sensitive to inhibition of PKA, which suggests that PKA-dependent phosphorylation of specific target(s) is responsible for the switch, implicating a role for cytosolic cAMP in this phenomenon. Therefore, the model we propose assumes that it is an uncontrolled increase in cAMP, due to ADM and prostaglandins (most probably prostacyclin) stimulation that initiate a sequence of events leading to a switch in G-protein coupling between adrenomedullin receptor and cellular response. This cAMP-dependent switch would thus be the trigger for the depressant effect of adrenomedullin on the ventricule during septic shock. The goal of this project is to test this hypothesis by quantifying cAMP in rat ventricular myocytes in conditions were adrenomedullin has a positive and a negative inotropic effect, and to confirm that pharmacological manipulations of these myocytes that inhibit the effects of adrenomedullin ultimately result in a decrease production of cAMP.

Researcher : Chan YS

Project Title:	30th Annual Conference of Society for Neuroscience Expression of N-Methyl-D-Aspartate Receptor Subunits and Induction of c-fos in Otolith Neurons in the Vestibular Nuclei of Postnatal Rats
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	11/2000

Abstract:

N/A

Project Title:	31st Annual Meeting of Society for Neuroscience Expression of Neurotrophin Receptors in Vestibular Nuclei During the Postnatal Development of the Rat
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	11/2001

Abstract:

N/A

Project Title:	The role of central glial cells in the pathogenesis of Parkinson's Disease
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2003

Abstract:

To employ immuno-hybridization histochemical methods to map the spatiotemporal distribution of different activated glial cells during the development of PD as induced by systemic administration of a neurotoxicant, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).

Project Title:	Functional maturation of excitatory and inhibitory synaptic receptors in canal-and otolith-related neurons of the inferior olive
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	12/2006
Completion Date:	11/2009

Abstract:

To examine developmental change of excitatory postsynaptic currents at glutamate synapses on canal- and otolith-related inferior olivary neurons; to examine developmental change of inhibitory postsynaptic currents at GABAergic synapses on canal- and otolith-related inferior olivary neurons.

Project Title:	XXIV Annual Conference of Indian Academy of Neurosciences Development Refinement of Spatial Recognition Circuits
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	12/2006

Abstract:

N/A

Project Title:	Postnatal γ-aminobutyric acid transmission is critical for the formation of a three-dimensional spatial map.
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	01/2008

Abstract:

To determine whether functional organization of the gravity- and rotation-related spatial reference is perturbed by perinatal blockade of GABAergic synapses in the VN; to examine if the perturbations applied later in the postnatal period have any effect on the spatial coding capacities of VN and IO neurons in the mature brain; to examine if perinatal perturbations of GABA synapses has any effect on vestibular reflexes and behaviors in the adult.

Project Title:	Role of the thalamus in integrating spatial information and guiding navigation
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	04/2009

Abstract:

Vestibular cues arising from end organs within the inner ear are critical for providing directional signals to the central nervous system. These vestibular inputs, however, must be transformed considerably in order to signal head direction. Accurate perception of one's spatial orientation within the environment then constitutes the framework for navigation in space. Nevertheless, the neural circuitry that accomplishes this signal processing has not been fully established. Functional studies are therefore needed to determine whether thalamus, as an important ascending relay station of the vestibular pathway, mediates vestibular influences for the determination of head direction as well as guides behavior during spatial navigation. An emerging concept in sensory development is that sensory perturbation in the postnatal critical period will result in deficient neural connections that deter the orderly establishment of sensory functions in the mature animal. Studies in the visual, auditory and somatosensory systems have realized the importance of this concept. It remains to be determined whether a critical period exists for the developmental establishment of spatial reference within the vestibular system. Since neural networks within the vestibular nucleus (VN) is shaped by glutamatergic inputs arising from the vestibular afferent, we reason that modification of glutamatergic transmission during the critical period should lead to derangement of the spatial map in the ascending vestibular pathway, thereby resulting in behavioral dysfunction. The first specific aim is to determine whether thalamic neurons in the ascending vestibular circuitry process spatial information of different directions. Immunohistochemical expression of c-fos will be used as activity indicators for the identification of functionally activated neurons within the developing network of the thalamus. Both the critical maturation period and postnatal distribution of neuronal subpopulations within the thalamus will be mapped. These will serve as a reference framework for our second specific aim. Using the above approach, we will test the hypothesis that thalamic neurons are critical neural substrate for determining head direction and in spatial navigation.

Project Title:	Neuroscience 2009 Maturation profile of inhibitory and excitatory postsynaptic currents in central vestibular neurons of rats
Investigator(s):	Chan YS
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	10/2009
Completion Date:	10/2009

Abstract:

N/A

Project Title:	Determinants of developmental plasticity in the vestibular system
Investigator(s):	Chan YS, Shum DKY
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	11/2009

Abstract:

To determine the role of AMPA and NMDA receptors in modulating functional maturation of VN neurons and otolith-related behavior; to examine if perinatal perturbations of glutamatergic synapses in the VN affect basal synaptic transmission and long-term synaptic plasticity in the adult cerebellum.

List of Research Outputs

Cai S., Shum D.K.Y., Chan Y.S. and Fu X.B., Outstanding Abstract Prize (Poster Category), Research Center of Heart, Brain, Hormone & Healthy Aging. 2010.

Cham W.C., Ma C.W., Zhang Y., Xie H., Yung W.H., Chan Y.S. and Shum D.K.Y., The Regulatory Role of Heparanase in Synaptic Plasiticity at Hippocampus, 14th Research Postgraduate Symposium, December 2 & 3, 2009, The University of Hong Kong. 2009.

Cham W.C., Ma C.W., Zhang Y., Xie H., Yung W.H., Chan Y.S. and Shum D.K.Y., The regulatory role of heparanase of synaptic plasticity in hippocampus, Society Neuroscience Abstract (USA). 2009, 318.3/C4.

Chan Y.S., Challenges of Medical Education Reform, Proc. 12th Medical Education Conference for China Mainland, Taiwan and the Hong Kong Region. 2009, 31-32.

Chan Y.S., Challenges of Medical Education Reform, [12^th Medical Education Conference for China Mainland, Taiwan and the Hong Kong Region; Nanning, China. Nov. 19-22, 2009]. 2009.

Chan Y.S. and He J.F., Corticothalamic gating of auditory information , J. Physiological Sciences (Suppl 1) [36^th Int’l Congress of International Union of Physiological Sciences Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 109.

Chan Y.S., Corticothalamic gating of auditory information, [36^th Int’l Congress of International Union of Physiological Sciences; Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009.

Chan Y.S., Development of spatial recognition: From receptors to behavior, Abstracts of International Symposium “From Genes to Behavior: Function and Dysfunction” [Seoul, Korea. July 24-25, 2009]. 2009, 4.

Chan Y.S., Development of spatial recognition: From receptors to behavior, [Int’l Symposium From Genes to Behavior: Function and Dysfunction; Seoul, Korea. July 24-25, 2009]. 2009.

Chan Y.S., Editor in: BrainNavigator. Elsevier (Amsterdam, The Netherland), 2010.

Chan Y.S., Formation of brain map for spatial perception, Neuroscience Bulletin (Suppl 1) [8th Biennial Conference of Chinese Society for Neuroscience. Guangzhou. Nov. 7-10, 2009]. 2009, 25: 31.

Chan Y.S., Formation of brain map for spatial perception, [8^th Biennial Conference of Chinese Society for Neuroscience; Guangzhou, China. Nov. 7-10, 2009] . 2009.

Chan Y.S., Journal Editor in: Acta Physiologica Sinica. Science Press (Shanghai, China), 2010.

Chan Y.S., Journal Editor in: Behavioral and Brain Functions. BioMedCentral (London, UK), 2010.

Chan Y.S., Journal Editor in: Experimental Brain Research. Springer (Heidelberg, Germany), 2010.

Chan Y.S., Journal Editor in: Neurochemistry International. Elsevier (Amsterdam, The Netherland), 2010.

Chan Y.S., Journal Editor in: Neuroembryology and Ageing. Karger (Basel, Switzerland), 2009.

Chan Y.S., Journal Editor in: Neuroscience Research. Elsevier (Amsterdam, The Netherland), 2010.

Chan Y.S., Journal Editor in: Open Zoology Journal. Bentham Science Publishers (U.A.E.), 2010.

Chan Y.S., Multidisciplinary approach to the understanding of neural correlates for spatial recognition, [Mahidol University, Bangkok, Thailand. Jan. 28, 2010]. 2010.

Chan Y.S., Neural correlates of head direction signals, [Nanjing University, China. Aug. 20, 2009]. 2009.

Chan Y.S., Plasticity in spatial navigation: from molecule to behavior, Proceedings of 14^th Scientific Conference of Thai Neuroscience Society. 2010, 2.

Chan Y.S., Plasticity of spatial navigation: From molecule to behavior, [14^th Conference of Thai Neuroscience Society; Bangkok, Thailand. Feb. 1-2, 2010] . 2010.

Chan Y.S., Problem-based teaching in the medical curriculum. , Int’l. Symposium on Medical Education Reform. [Taipei, Taiwan. Oct. 10, 2009.] . 2009, 109-111.

Chan Y.S., Problem-based teaching in the medical curriculum, [Int’l Symposium on Medical Education Reform; Taipei, Taiwan. Oct. 10, 2009]. 2009.

Chan Y.S., Problem-based teaching of Clinical Neuroscience., [8^th Biennial Conference of Chinese Society for Neuroscience; Guangzhou, China. Nov. 7-10, 2009]. 2009.

Chan Y.S., Spatial map formation in the brain: From molecules to behavior, [Fudan University Shanghai, China. Oct. 27, 2009]. 2009.

Chan Y.S., Spatial navigation and perception, [Int’l Symposium on Brain Science, Consciousness and Religion Nagoya, Japan. Nov. 27-29, 2009]. 2009.

Cheah K.S.E., Au Y.K., Szeto Y.Y., Wynn S., Chan Y.S., Cheung K.M.C., Chan W.Y., Lovell-Badge R.H., Chan D. and Fritzsch B., Molecular and developmental insights into the pathogenesis of the SOX9Y440Xcampomelic dysplasia mutation, 16th International Society of Developmental Biologists Congress 6-10th September 2009 Edinburgh International Conference Centre, UK . 2009.

Chu J.Y.S., Lee T.O., Chan Y.S. and Chow B.K.C., Secretin : a neurosecretory factor regulating body water homeostasis, 9th International Symposium on VIP, PACAP and Related Peptides, Kagoshima, Japan. 2009.

Chu J.Y.S., Lee T.O., Lai C.H., Vaudry H., Chan Y.S., Yung W.H. and Chow B.K.C., Secretin as a neurohypophysial factor regulating body water homeostasis, Proceedings of National Academy of Sciences,USA. 2009, 106: 15961-15966.

Chu J.Y.S., Lee T.O., Chan Y.S. and Chow B.K.C., Secretin: A neurosecretory factor regulating body water homeostasis, The 9th International Symposium on VIP, PACAP and Related Peptides. 2009.

Chu K.H., Zhang M., Wong E.Y.M., Szeto Y.Y., Chan Y.S., Cheah K.S.E. and Sham M.H., Best Poster Award: Sox10 mutation affects cochleo-vestibular ganglion gliogenesis, 43rd Annual Meeting for the Japanese Society of Developmental Biologists, Kyoto, Japan, 20-23 June, 2010.. 2010.

Chu K.H., Zhang M., Wong E.Y.M., Szeto Y.Y., Chan Y.S., Cheah K.S.E. and Sham M.H., Best Poster Award: Sox10 mutation affects gliogenesis of the cochleo-vestibular ganglion, 2010 Hong Kong Inter-University Biochemistry Postgraduate Symposium, 15 May 2010. 2010.

Chu K.H., Zhang M., Wong E.Y.M., Szeto Y.Y., Chan Y.S., Cheah K.S.E. and Sham M.H., Sox10 mutation affects cochleo-vestibular ganglion gliogenesis, 43rd Annual Meeting for the Japanese Society of Developmental Biologists, Kyoto, Japan, 20-23 June. 2010.

Chu K.H., Zhang M., Wong E.Y.M., Szeto Y.Y., Chan Y.S., Cheah K.S.E. and Sham M.H., Sox10 mutation affects gliogenesis of the cochleo-vestibular ganglion, 2010 Hong Kong Inter-University Biochemistry Postgraduate Symposium, 15 May 2010.

Gao J., Cheung R.T.F., Lee T.M.C., Chu L.W., Cheung C., Qiu D., Mak H.K.F. and Chan Y.S., Declined frontal white matter integrity in Alzheimer’s disease: a diffusion tensor imaging study, Medical Research Conference, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, 2010. Hong Kong Medical Journal. 2010, 16 (suppl 1): 21.

Gao J., Cheung R.T.F., Lee T.M.C., Chu L.W. and Chan Y.S., Task-induced brain deactivation reflects the altered default model network in normal and abnormal aging, Fifth International Symposium on Healthy Aging, Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, 6–7 March 2010, The Ballroom, Sheraton Hong Kong Hotel & Towers, Tsimshatsui, Hong Kong; Abstract Book. 2010, 46.

Gao J., Cheung R.T.F., Lee T.M.C., Chu L.W., Cheung C., Fung G., Qiu D.G. and Chan Y.S., The anteroposterior pattern of white matter decline in normal and abnormal aging supports retrogenesis: a diffusion tensor imaging study, Fifth International Symposium on Healthy Aging, Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, 6–7 March 2010, The Ballroom, Sheraton Hong Kong Hotel & Towers, Tsimshatsui, Hong Kong; Abstract Book. 2010, 46.

Gao Y.P., Liu C., Chan Y.S. and He J.F., Contribution of thalamic reticular nucleus to the synchronization of spindle oscillation in the thalamocortical network, Neuroscience Bulletin (Suppl 1). [8th Biennial Conference of Chinese Society for Neuroscience. Guangzhou. Nov. 7-10, 2009]. 2009, 25: 353-354.

Han L., Lai S.K., Lai C.H. and Chan Y.S., Electrophysiological study of synaptic transmission in inferior olivary neurons of postnatal rats, Society Neuroscience Abstract (USA) . 2009, 812.5/B37.

Hu H., Lai S.K., Lai C.H. and Chan Y.S., Developmental profile of inhibitory synaptic transmission in medial vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.8/B63.

Lai C.H., Yiu N.S.C., Lai S.K., Ng K.P., Yung K.K., Shum D.K.Y. and Chan Y.S., Maturation of canal-related brainstem neurons in the detection of horizontal angular acceleration in rats, Journal of Comparative Neurology. 2010, 518: 1742-1763.

Lai S.K., Tse Y.C., Hu H., Wong T.P., Yung W.H. and Chan Y.S., Maturation profile of inhibitory and excitatory postsynaptic currents in central vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.14/B62.

Lau Y.P., Lai C.H. and Chan Y.S., Developmental responsiveness of thalamic neurons to vertical sinusoidal linear acceleration, Society Neuroscience Abstract (USA). 2009, 813.5/B53.

Li M., Chan Y.S. and Shum D.K.Y., Chondroitin sulfate moieties expressed by migrating motor neurons in explant cultures of the rat hindbrain, Proceedings of 32nd Annual Meeting of Japan Neuroscience Society . 2009, P1-e10.

Li M., Chan Y.S. and Shum D.K.Y., Expression of chondroitin sulfotransferases in cranial motor neurons in the embryonic rat hindbrain, Neuroscience Bulletin (Suppl 1). [8^th Biennial Conference of Chinese Society for Neuroscience. Guangzhou. Nov. 7-10, 2009]. 2009, 25: 113.

Liu C., Gao Y.P., Gao L.X., Meng X.K., Yu Y.Q., Chan Y.S. and He J.F., The spindle oscillations in the thalamic reticular nucleus, auditory thalamus, and cortex, Neuroscience Bulletin (Suppl 1). [8th Biennial Conference of Chinese Society for Neuroscience. Guangzhou. Nov. 7-10, 2009]. 2009, 25: 353.

Ma C.W., Lai C.H., Lai S.K., Tse Y.C., Yung K.K., Shum D.K.Y. and Chan Y.S., Developmental distribution of vestibular nuclear neurons responsive to different speeds of horizontal translation, Brain Research. 2010, 1326: 62-67.

Ma C.W., Lai C.H., Chan Y.S. and Shum D.K.Y., In vitro and in vivo studies of perineuronal glycosaminoglycans in synaptic functions, Society Neuroscience Abstract (USA) . 2009, 719.10/D6.

Ma C.W., Zhang Y., Cham W.C., Chan Y.S. and Shum D.K.Y., Role of heparanase in synaptic plasticity at the hippocampus and vestibular nucleus , J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 145.

Ng K.P., Lai C.H. and Chan Y.S., Postnatal NMDA receptor blockade alters the characteristics of canal-related inferior olivary neurons, Society Neuroscience Abstract (USA) . 2009, 813.15/B63.

Ng K.P., Han L., Lau P.Y.P., Li C., Lai C.H., Shum D.K.Y. and Chan Y.S., Postnatal refinement of gravity-related spatial coding to the central vestibular circuitry, J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences. Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 204.

Shea G.K.H., Tsui Y.P., Chan Y.S. and Shum D.K.Y., Bone marrow-derived Schwann cells achieve fate commitment – a prerequisite for remyelination therapy, Experimental Neurology. 2010, 224: 448-458.

Shea G.K.H., Tsui Y.P., Shum D.K.Y. and Chan Y.S., Fate Commitment in Bone Marrow Stromal Cell-derived Schwann Cells is Dependant on Axonal Contact, 14th Research Postgraduate Symposium, December 2 & 3, 2009, The University of Hong Kong. 2009.

Shea G.K.H., Tsui Y.P., Chan Y.S. and Shum D.K.Y., Fate commitment in bone marrow stromal cells derived Schwann cells is dependant on axonal contact, Proceedings of 32nd Annual Meeting of Japan Neuroscience Society. 2009, P2-d12.

Sun X., Guo Y.P., Chan Y.S. and He J., Time course of cortically induced Fos expression in auditory thalamus and midbrain after bilateral cochlear ablation, Neuroscience. 2009, 60: 186-197.

Tao K.P., Lai S.K., Chan Y.S., Sham M.H. and Chan S.Y., Tspyl2 is involved in Cellular Stress Response and Brain Function, 14^th Research Postgraduate Symposium, HKU, 2-3 December 2009.

Tsang K.H., Lai S.K., Chan Y.S. and Chan S.Y., Testis-specific Protein Y-linked-Like 2 (Tspyl2) Regulates Hippocampal Long-term Potentiation via NMDA Receptors Expression and p38MAPK Activity, 14^th Research Postgraduate Symposium, HKU, 2-3 December 2009.

Tsang K.H., Tao K.P., Lai S.K., Chan Y.S. and Chan S.Y., Tspy12 regulates hippocampal long-term potentiation via NMDA receptor subunits Nr2a and Nr2b expression, 43^rd Annual Meeting for the Japanese Society of Developmental Biologists (Jointly sponsored by the Asia-Pacific Developmental Biology Network), Japan, 20-23 June 2010.

Tsui Y.P., Chan Y.S. and Shum D.K.Y., Bone marrow stromal cell-derived oligodendrocyte precursor cells: A new perspective in CNS myelin repair, 2010 Hong Kong Inter-University Biochemistry Postgraduate Symposium, CUHK, Hong Kong, 15 May,. 2010.

Yu K., Wang N.Q., Zhang Z., Chan Y.S. and He J.F., The influence of superficial layer neuron in auditory cortex, Neuroscience Bulletin (Suppl 1). [8th Biennial Conference of Chinese Society for Neuroscience. Guangzhou. Nov. 7-10, 2009]. 2009, 25: 120.

Researcher : Cheng WT

List of Research Outputs

Tang W.H., Cheng W.T., Kravtsov G.M., Tong X.Y., Hou X.Y., Chung S.K. and Chung S.S.M., Cardiac contractile dysfunction during acute hyperglycemia due to impairment of SERCA by polyol pathway-mediated oxidative stress, American Journal of Physiology and Cell Physiology. 2010, 299: C643-C653.

Researcher : Chung SSM

Project Title:	Hyperglycemia-induced cardiomyopathy
Investigator(s):	Chung SSM
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	03/2009
Completion Date:	10/2009

Abstract:

Our long-term goal is to understand why diabetic patients are more susceptible to cardiovascular diseases. Here we plan to study the mechanism of diabetic cardiomyopathy. This is an extension of my MPhil student, Mr. Tim Cheng's thesis work. He already demonstrated that inhibition of adlose reductase (AR) and sorbitol dehydrogenase, the two enzymes in the polyol pathway, ameliorated hyperglycemia-induced contractile dysfunction of the heart and abnormal calcium signaling profile of the cardiomyocytes. Experiments proposed here, represented by the Objectives below, will help us understand the mechanisms involved so that his work can be published in prestigious journals. Objectives: 1. Determine the role of polyol pathway in hyperglycemia-induced impairment of SERCA activity 2. Determine if AR or SDH inhibition attenuate hyperglycemia-mediated decrease in GSH and increase in ROS in the heart

List of Research Outputs

Chen A.Y.S., Chung S.S.M. and Chung S.K., Aldose reductase deficiency improves wallerian degeneration and nerve regeneration in diabetic thy1-YFP mice, Journal of Neuropathology & Experimental Neurology:. 2010, 69(3): 294-305.

Srivastava S., Vladykovskaya E., Barski O.A., Spite M., Kaiserova K., Petrash J.M., Chung S.S.M., Hunt G., Dawn B. and Bhatnagar A., Aldose Reductase Protects Against Early Atherosclerotic Lesion Formation In Apolipoprotein E-null Mic, Circulation Research. 2009, 105: 793-802.

Tang W.H., Cheng W.T., Kravtsov G.M., Tong X.Y., Hou X.Y., Chung S.K. and Chung S.S.M., Cardiac contractile dysfunction during acute hyperglycemia due to impairment of SERCA by polyol pathway-mediated oxidative stress, American Journal of Physiology and Cell Physiology. 2010, 299: C643-C653.

Tang W.H., Kravtsov G.M., Sauert M., Tong X.Y., Hou X.Y., Wong T.M., Chung S.K. and Chung S.S.M., Polyol pathway impairs the function of SERCA and RyR in ischemic-reperfused rat hearts by increasing oxidative modificaitons of these proteins, Journal of Molecular and Cellular Cardiology. 2010, 49: 58-69.

Tong H.Y., Guo J.J., Xu S.X., Mak M.C., Chung S.K., Chung S.S.M., Huang A.L. and Ko B.C.B., Inducible nucleosome depletion at OREBP-binding-sites by hypertonic stress, PLoS ONE. 2009, 4(12): e8435.

Yagihashi S., Mizukami H., Ogasawara S., Yamagishi S.I., Nukada H., Kato N., Hibi C., Chung S.K. and Chung S.S.M., The role of the polyol pathway in acute kidney injury caused by hindlimb ischaemia in mice, Journal of Pathology. 2010, 220: 530-541.

Yeung C.M., Lo A.C.Y., Cheung A.K.H., Chung S.S.M., Wong D.S.H. and Chung S.K., More severe type 2 diabetes-associated ischemic stroke injury is alleviated in aldose reductase-deficient mice, Journal of Neuroscience Research. 2010, 88: 2026-2034.

Yeung P.K.K., Lo A.C.Y., Leung J.W.C., Chung S.S.M. and Chung S.K., Targeted overexpression of endothelin-1 in astrocytes leads to more severe cytotoxic brain edema and higher mortality, Journal of Cerebral Blood Flow & Metabolism. 2009, 29: 1891-1902.

Researcher : Fung ML

Project Title:	Mechanistic role of hypoxia-inducible factor-1 in differentiation of embryonic stem cells into cardiomyocytes
Investigator(s):	Fung ML
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	06/2008
Completion Date:	05/2010

Abstract:

• Recent studies have demonstrated that hypoxia may play a critical role in the proliferation, proper differentiation and maintenance of the cardiovascular system in the embryo. But, the cellular and molecular mechanisms underlying the effect of hypoxia on cardiomyocyte (CMC) differentiation remain unclear. • Preliminary studies in our laboratories indicated that hypoxia could promote the differentiation of embryonic stem cells (ESCs) into CMCs; the transplanted undifferentiated mESCs could survival and differentiation in myocardial infarction heart but not in normal heart. In addition, our preliminary data not only shows an expression of HIF-1 and HIF-target genes in the undifferentiated hESCs and its derived CMCs, but also demonstrated the functional operation of the HIF-1 pathway upon chemical-induced hypoxia. This strongly suggests the role played by the HIF-1 pathway in the hypoxia-induced CMC differentiation. • Nevertheless, the mechanistic involvement of the HIFs and the role of HIF-1 pathway in the hypoxia-induced CMC differentiation in hESCs are very poorly understood. • We hypothesize that HIF-1 plays an important role in the differentiation of ESCs into cardiomyocyte (CMC). • Objective of this proposal is to determine whether HIF-1 pathway is involved in the differentiation of CMCs during hypoxia. Hence, proposed studies are (1) to culture the ESC in the presence of chemical hypoxia inducers, so as to activate the HIF-1 pathway under normoxic conditions, and (2) to manipulate the genetic content of the ESC by overexpression of HIF-1α in the ESC. These will be followed by the measurement of the functional markers via Ca2+ handling and ionic channels activities in the differentiation of ESCs into the CMCs.

Project Title:	Roles of pro-inflammatory cytokines in the carotid body in intermittent hypoxia
Investigator(s):	Fung ML
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	03/2009

Abstract:

• Chronic intermittent hypoxia is a common pathophysiological condition associated with chronic diseases such as cardiac dysfunction, pulmonary diseases or sleep apnea. Previous studies have shown that the carotid body undergoes maladaptive changes in intermittent hypoxia responsible for the pathophysiological development of cardiovascular morbidity such as hypertension. • Recently we have shown that: (1) the mRNA expression of proinflammatory cytokines interleukin (IL)-1b, IL-6, tumor necrosis factor (TNF)-a is present in the carotid body of rats; (2) the expressions of cytokines and their receptors are localized in the lobules of chemosensitive glomus cells containing tyrosine hydroxylase, (3) cytokines concentration-dependently elevate intracellular calcium responses to acute hypoxia in the dissociated chemosensitive cells, and (4) the gene transcripts of inflammatory mediators are increased in the carotid body of rats treated with hypoxia. These data suggest that the expression of pro-inflammatory cytokines in the carotid body plays active roles in the modulation of the carotid chemoreceptor activity and in the local inflammatory response under hypoxia condition. • The mechanistic involvement of the proinflammatory cytokine pathways in the pathophysiological changes in the carotid body in chronic intermittent hypoxia is largely unknown at the moment. We are particularly interested in intermittent hypoxia because in clinical conditions many hypoxic episodes are not continuous but rather intermittent in nature, which cause a unique set of pathogenic events, including systemic hypertension. • In this proposal, we postulated that the pro-inflammatory cytokines in the rat carotid body play a pathophysiological role in the modulation of carotid chemoreceptor function and local inflammatory events in intermittent hypoxia. • Objectives of this study are: (1) to determine the effect of intermittent hypoxia on the gene expression of IL-1b, IL-6, TNF-a and their receptors, and the local inflammation in the carotid body; (2) to determine the functional changes associated with the cytokine expression in the carotid body in intermittent hypoxia. • Experimental studies with molecular analysis, intracellular calcium measurement and electrophysiology are proposed to examine the pathophysiological roles of the locally expressed cytokines in the carotid body in intermittent hypoxia.

Project Title:	Molecular basis for the inhibition of large conductance calcium-activated potassium channel by chronic intermittent hypoxia
Investigator(s):	Fung ML
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	03/2010

Abstract:

• Recurrent episodes of severe hypoxia occur in adult and juvenile patients with central or obstructive sleep apnea, respiratory insufficiency and sudden infant death syndrome. The clinical manifestation is closely associated with chronic intermittent hypoxia (CIH), which leads to neurological dysfunction and cognitive impairment [1]. Indeed, neuronal brain damage has been reported in patients with sleep apnea [2]. • Recently we have shown that: (1) elevated levels of reactive oxygen species (ROS) induced by CIH could account for the apoptosis in the hippocampus [3]; (2) CIH induces significant decreases in large conductance calcium-activated potassium (BK) channel activity in hippocampal neurons [4]; (3) administration of free radical scavenger ameliorates levels of oxidative stress and the CIH-induced BK inhibition [5]. These data suggest oxidative modulation of the BK channel under CIH conditions. • The molecular mechanism underlying the inhibition of the activity of BK channels in hippocampal neurons under CIH conditions is largely unknown at the moment. In this proposal, we aimed to examine the hypothesis that oxidative modulation of the BK channel at cysteine residues by ROS mediated the CIH-induced BK inhibition in hippocampal neurons. • Objectives of this study are: (1) to determine the effects of intermittent hypoxia and oxidative modulation on the BK channel activity in the hippocampal neurons and in cultured cells transfected with BK channels; (2) to determine the effect of oxidative modulation of cysteine residues on the BK channel activity in intermittent hypoxia. • Experimental studies with molecular analysis and electrophysiology are proposed to define the molecular basis of oxidative modulation of the BK channel activity in the hippocampus in intermittent hypoxia. Reference: 1. Halbower, A. C., et al. (2006) PLoS Med 3, e301. 2. Minoguchi, K., et al. (2007) Am J Respir Crit Care Med 175, 612-7. 3. Hung, M.W., et al. (2008) Journal of Pineal Research 44,214-21. 4. Tjong, Y.W., et al. (2008) Free Radical Biology and Medicine 44, 547-57. 5. Tjong, Y.W., et al. (2008) Journal of Pineal Research, 44,234-43.

List of Research Outputs

Fung M.L., Editorial Board Member, Adaptive Medicine. 2009.

Lau C.F., Ng K.M., Tipoe G.L. and Fung M.L., Chronic intermittent hypoxia induces oxidative stress and decreases NO production in the carotid artery of rats. The 13^th Annual Scientific Meeting of the Institute of Cardiovascular Science and Medicine, P16, 12/2009, (Journal of the Hong Kong College of Cardiology). 2009, 17(2):61.

Lau C.F., Hung M.W., Ng K.M., Tipoe G.L. and Fung M.L., Oxidative injury and inflammation in the lung of rats exposed to chronic intermittent hypoxia, Physiology Symposium 2009, HKU,Hong Kong 5/2009.

Lau C.F., Ng K.M. and Fung M.L., Oxidative stress and inflammation are involved in the endothelial dysfunction of rat carotid artery in chronic intermittent hypoxia, The Fifth International Symposium on Healthy Aging, HKU, Hong Kong, 3/2010.

Li J., Fung M.L., Xu A., Tsao G.S.W. and Leung W.K., Lipopolysaccharide causes hypoxia-inducible factor 1-alpha accumulation in gingival fibroblasts, 39^thAnnual Meeting of the American Association for Dental Research, Washington DC, 3/2010.

Lin R., Lau C.F., Wang J., Ni Y., Fung M.L. and Huang J., Reduced neuronal nitric oxide production in KIF5b-deficiency mice, 2010 Hong Kong Inter-University Biochemistry Postgraduate Symposium, CUHK, Hong Kong, 15 May,. 2010.

Liu Y. and Fung M.L., Chronic hypoxia induces oxidative stress and local inflammation in rat adrenal medulla, 14^th Research Postgraduate Symposium, HKU, P1.18, 12/2009.

Liu Y. and Fung M.L., Chronic intermittent hypoxia induces oxidative stress and local inflammation in rat adrenal medulla , The Fifth International Symposium on Healthy Aging, HKU, Hong Kong 3/2010.

Liu Y. and Fung M.L., Oxidative stress and local inflammation in rat adrenal medulla in chronic hypoxia. The 13^thAnnual Scientific Meeting of the Institute of Cardiovascular Science and Medicine 12/2009, (Journal of the Hong Kong College of Cardiology). 2009, 17(2):61: 15.

Liu Y., Lau C.F., Ng K.M. and Fung M.L., Up-regulated eNOS expression and NO production in rat adrenal gland in chronic hypoxia, Physiology Symposium 2009, HKU, Hong Kong 5/2009.

Ng K.M., Lee Y.K., Chan Y.C., Lai K.W.H., Fung M.L., Li R.A., Siu D.C.W. and Tse H.F., Exogenous expression of HIF-1alpha promotes cardiac differentiation of embryonic stem cells., Journal of Molecular and Cellular Cardiology. 2010, 48(6): 1129-37.

Ng K.M., Lee Y.K., Chan Y.C., Lai W.H.K., Fung M.L., Li R.A., Siu D.C.W. and Tse H.F., Exogenous expression of HIF-1a promotes the cardiac differentiation of embryonic stem cells, Journal of Molecular and Cellular Cardiology. 2010, 48(6): 1129-1137.

Ng K.M., Lee Y.K., Fung M.L., Li R.A., Siu D.C.W. and Tse H.F., Hypoxia promotes cardiac differentiation of human embryonic stem cells, Physiology Symposium 2009, HKU, Hong Kong 5/2009.

Shen J., Lee W.S., Li Y. and Fung M.L., INTERACTION OF CAVEOLIN-1, NITRIC OXIDE AND NITRIC OXIDE SYNTHASES IN HYPOXIC HUMAN SK-N-MC NEUROBLASTOMA CELLS AND RAT ISCHEMIC BRAINS, 6th World Congress for Brain Mapping and Image Guided Therapy. Harvard Medical School, Boston, USA, 2009.

Tipoe G.L., Leung T.M., Liong E.C., Lau T.Y.H., Fung M.L. and Nanji A.A., Epigallocatechin-3-gallate (EGCG) reduces liver inflammation, oxidative stress and fibrosis in carbon tetrachloride (CCl₄)-induced liver injury in mice, Toxicology. 2010, 273: 45-52.

Tipoe G.L., Ho M.C.T., Liong E.C., Leung T.M., Lau T.Y.H., Fung M.L. and Nanji A.A., Voluntary oral feeding of rats not requiring a very high fat diet is a clinical relevant model of non-alcoholic fatty liver disease (NAFLD), Histology and Histopathology. 2009, 24(9): 1161-1169.

Yeung H.M., Hung M.W., Kravtsov G.M. and Fung M.L., Chronic intermittent hypoxia exacerbates oxidative stress and deteriorates calcium homeostasis in rat hearts. 63^rd High Blood Pressure Research Conference, American Heart Association, USA 9/2009.

Researcher : Han L

List of Research Outputs

Han L., Lai S.K., Lai C.H. and Chan Y.S., Electrophysiological study of synaptic transmission in inferior olivary neurons of postnatal rats, Society Neuroscience Abstract (USA) . 2009, 812.5/B37.

Ng K.P., Han L., Lau P.Y.P., Li C., Lai C.H., Shum D.K.Y. and Chan Y.S., Postnatal refinement of gravity-related spatial coding to the central vestibular circuitry, J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences. Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 204.

Researcher : Han L

List of Research Outputs

Researcher : Hao Q

Project Title:	Structural studies of reaction intermediates
Investigator(s):	Hao Q
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	09/2008
Completion Date:	08/2009

Abstract:

Understanding of the atomic movements involved in an enzymatic reaction needs structural information on the active and inactive native enzyme molecules, and on the enzyme-substrate, enzyme-intermediate and enzyme-product(s) complexes. The enzymatic cleavage of the nicotinamide-glycosidic bond on nicotinamide adenine dinucleotide (NAD) has been proposed to go through an oxocarbenium ion-like transition (non-covalent) state or a covalent intermediate (Sauve et al, 2000). Due to the instability of the ionic intermediate, there has been no structural report on such a transient reactive species. Human CD38 is an ectoenzyme that can use NAD to synthesize two calcium mobilizing molecules (Lee, 1993). We plan to determine high resolution crystal structures of the enzyme complexed with the intermediates, with substrates and with products. The structural analysis of these complexes would provide insights into the mechanisms of nicotinamide cleavage, intermediate stabilization and products generation.

Project Title:	A new method for macromolecular structure determination: envelope-based phasing
Investigator(s):	Hao Q
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	10/2009

Abstract:

1) Optimize experimental and data analysis techniques to determine molecular envelopes using small-angle X-ray scattering (SAXS); 2)Continue the development of a computer program (FSEARCH) for locating envelopes in the crystallographic unit cell; 3) Extend phases to high resolution and solve crystal structures.

Project Title:	Structure-based drug design against the influenza virus hemagglutinin
Investigator(s):	Hao Q
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Applied Research
Start Date:	06/2010

Abstract:

The hemagglutinin protein (HA) of influenza A viruses is a homotrimer that binds to sialic receptors on cells. The low pH in the endosomes causes irreversible conformational changes of the HA that lead to the fusion of the viral and cellular membranes and hence uncoating of the virus. A series of chemicals have been shown to inhibit these conformational changes and therefore inhibit virus replication [1]. We propose to study the structure-activity relationships for these inhibitors targeting the second phylogenetic HA group that includes both the H1 HA of viruses currently circulating in humans and the H5 HA of pathogenic H5N1 viruses. The structural study would improve binding affinity, potentially leading to an effective antiviral drug against viruses containing these HAs.

List of Research Outputs

Cornaby S., Szebenyi D.M.E., Smilgies D.M., Schuller D.J., Gillilan R., Hao Q. and Bilderback D.H., Feasibility of one-shot-per-crystal structure determination using Laue diffraction., Acta Cryst. D. 2010, 66: 2-11.

Graeff R., Liu Q., Kriksunov I.A., Kotaka M., Oppenheimer N., Hao Q. and Lee H.C., Mechanism of Cyclizing NAD to Cyclic ADP-ribose by ADP-ribosyl Cyclase and CD38, Journal of Biological Chemistry. 2009, 284: 27629-27636.

Hao Q., Structural Biology Initiative at the LKS Faculty of Medicine, Joint Annual Scientific Meeting of the Hong Kong Society of Neurosciences and the Biophysical Society of Hong Kong . 06/2010, 2010.

Hao Q., Structural study of Enzymatic Reaction Intermediates, The 3rd Chinese Structural Biology Discussion Meeting, Sanya, China. 2010.

Hao Q., Synchrotron-base Structural Biology: Challenges and Opportunities, SSRF Phase II Discussion Meeting, Shanghai, China. 2010.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Croucher ASI 2009 "Structure-based screening and design of ligands for protein targets". 2009.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Joint Meeting of the HK Society of Neurosciences and the Biophysical Society of Hong Kong. 2010.

Liu Q., Graeff R., Kriksunov I.A., Jiang H., Zhang B., Oppenheimer N., Lin H., Potter B.V.L., Lee H.C. and Hao Q., Structural Basis for Enzymatic Evolution from a Dedicated ADP-ribosyl Cyclase to a Multifunctional NAD Hydrolase, Journal of Biological Chemistry. 2009, 284: 27637-27645.

Researcher : Hu H

List of Research Outputs

Hu H., Lai S.K., Lai C.H. and Chan Y.S., Developmental profile of inhibitory synaptic transmission in medial vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.8/B63.

Lai S.K., Tse Y.C., Hu H., Wong T.P., Yung W.H. and Chan Y.S., Maturation profile of inhibitory and excitatory postsynaptic currents in central vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.14/B62.

Researcher : Hung MW

List of Research Outputs

Lau C.F., Hung M.W., Ng K.M., Tipoe G.L. and Fung M.L., Oxidative injury and inflammation in the lung of rats exposed to chronic intermittent hypoxia, Physiology Symposium 2009, HKU,Hong Kong 5/2009.

Yeung H.M., Hung M.W., Kravtsov G.M. and Fung M.L., Chronic intermittent hypoxia exacerbates oxidative stress and deteriorates calcium homeostasis in rat hearts. 63^rd High Blood Pressure Research Conference, American Heart Association, USA 9/2009.

Researcher : Hwang ISS

List of Research Outputs

Li L., Hwang I.S.S., Tang F., O W.S. and Li Y.Y., Coexpression of adrenomedullin and its receptors in the reproductive system of the rat: effects on sterold secretion in rat ovary, Yakhteh Medical Journal. 2009, 11(1): 36.

Researcher : Kotaka M

Project Title:	X-ray crystallographic studies of MDA-5, a component of the retinoic acid inducible gene-I (RIG-I) like RNA helicase pathway of innate immunity response
Investigator(s):	Kotaka M
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	04/2009
Completion Date:	04/2010

Abstract:

In humans, RNA viruses are etiologic agents of infectious diseases posing major public health concerns. Upon viral infection, a variety of viral components, including double-stranded RNA (dsRNA), trigger anti-viral responses by the mammalian innate immune system. The innate immune system is not non-specific, rather, is able to discriminate between self and a variety of pathogens. The response to pathogens is initiated through the detection of pathogen components by host pattern recognition receptors (PRRs) which specifically recognizes different pathogen-associated molecular patterns such as viral DNA and RNA, pathogen cell wall components and flagellar proteins. The interaction between the PRR and its specific pathogen-associated molecular pattern will trigger intracellular signaling cascades resulting in the production of type-1 interferon (IFN) and proinflammatory cytokines. Of the major families of PRRs, retinoic acid inducible gene-I (RIG-I) like RNA helicases (RLHs) are involved in the detection of viral RNA that has invaded the cytoplasm. RLHs are a family of RNA helicases including RIG-I, melanoma differentiation associated gene 5 (MDA-5) and LGP-2 (Yoneyama et al, 2005; Yoneyama et al, 2004) . RIG-I and MDA5 elicit host response triggered by different viruses, while LGP-2 serves as a negative regulator. MDA5 appears to detect only picornaviruses whereas RIG-I is able to recognize a range of viruses including Hepatitis C virus, Sendai virus, influenza virus, rabies virus and Japanese encephalitis virus (Kato et al, 2006) (Loo et al, 2008). Upon recognition of viral RNA, RIG-I and MDA-5 recruits the adaptor protein, IPS-1, thereby initiating the cascade of type-1 IFN response. Recently, it has also been demonstrated that dihydroxyacetone kinase (DAK), associates with MDA-5 under physiological conditions and act as the negative regulator of MDA-5 (Diao et al, 2007). While there has been an explosion of knowledge in the understanding of the RLH pathway in recent years, still little is known about the underlying mechanisms of the activation of RIG-I and MDA-5 in response to RNA binding, especially with MDA-5. Therefore, this project aims to determine the structures of MDA-5 using X-ray crystallography in the hope of unraveling the mechanism by which MDA-5 recognizes viral RNA and also the structural basis of negative regulation of MDA-5 by its negative regulator, dihydroxyacetone kinase (DAK).

Project Title:	Towards the understanding of hyperactivation of RIG-I signalling pathway by influenza A H5N1: Structural studies on interaction of influenza A NS1 protein with TRIM25, an E3 ubiquitin ligase essential for RIG-I activation
Investigator(s):	Kotaka M, Hui PY
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	01/2010

Abstract:

In humans, RNA viruses, e.g. influenza A virus, are etiologic agents of infectious diseases posing major public health concerns. Influenza H5N1 virus is of particular concern as it poses pandemic threat due to its zoonotical transmission and its ability to cause severe and often fatal human diseases. Upon viral infection, a variety of viral components, including single-stranded and double-stranded RNA (ss- and dsRNA), trigger anti-viral responses by the mammalian innate immune system resulting in the production of type-1 interferon (IFN) and proinflammatory cytokines (1). The response is initiated through the detection of viral components by host pattern recognition receptors (PRRs) specifically recognizing different pathogen-associated molecular patterns such as viral DNA and RNA, pathogen cell wall components and flagellar proteins. Two major families of PRRs, namely Toll-like receptors (TLRs) and retinoic acid inducible gene-I (RIG-I) like RNA helicases (RLHs), are key sensors of viral infection (2,3). Hyper-induction of cytokines such as IFN by highly pathogenic avian influenza virus H5N1 contributes, at least in part, to the pathogenesis of H5N1 disease (4). Patients with H5N1 disease have higher serum concentrations of cytokines and chemokines than patients with seasonal influenza and fatal H5N1 cases have higher viral load and serum cytokine levels than those that survive. We have observed that upon influenza A infection, the RIG-I signalling pathway of cytokine induction is hyperactivated by H5N1 but not H1N1 at a similar viral replication level in infected cells. Retinoic acid inducible gene-I (RIG-I), a member of the RLHs, recognises influenza A viral RNA (vRNA) that has invaded the cytoplasm of host cells and elicit host response against the influenza A virus (5,6). Upon viral infection, RIG-I recognises and binds influenza A vRNA in a 5'-triphosphate-dependent manner (7,8) and undergoes conformational change in the presence of ATP and releases the N-terminal CARD domains. The CARDs can then interact with an adaptor protein IPS-1, also known as MAVS, VISA or CARDIF, mediating the downstream activation events resulting in the eventual induction of type-1 IFNs (9-12). For the CARDs of RIG-I to be able to interact with IPS-1 for the activation of the RIG-I signalling pathway to elicit host antiviral innate immunity, the CARDs needed to be ubiquitinated by the RING-finger E3 ubiquitin ligase TRIM25 (13). TRIM25 would interact with the first CARD domain, this interaction would mediate the delivery of Lys63-linked ubiquitin moiety to the second CARD domain of RIG-I. Ubiquitination of the second CARD domain would result in the efficient interaction with IPS-1 and the activation of the RIG-I signalling pathway. To evade recognition and activation of the RIG-I signaling pathway, viruses have evolved different strategies to inhibit the pathway. For influenza A virus, it has recently been shown that its nonstructural protein 1 (NS1) directly interacts with TRIM25, thereby inhibiting CARD ubiquitination of RIG-I and abolishes RIG-I-IPS-1 interaction and the activation of the downstream cascade of signalling response (14). It was also shown that despite sequence variations, NS1 proteins encoded by different influenza A strains interacted with TRIM25, indicating a conserved function of NS1 (14). However, the sequence variation in the NS1 protein in different influenza A strains may affect the affinity for TRIM25 binding, which may correlate with viral pathogenesis. Using siRNA interference, we have demonstrated that RIG-I and IPS-1 are involved in H5N1-mediated cytokine induction. We therefore postulate that the hyperactivation of RIG-I signaling pathway by H5N1 could be due to a weaker interaction between H5N1 NS1 and TRIM25 than that of H1N1 resulting in a less pronounced inhibitory effect on RIG-I ubiquitination by TRIM25. Therefore the main aim of the project is to determine the structures of TRIM25-RIG-I CARD complex and NS1-TRIM25 complexes of influenza A H5N1 and H1N1 subtypes using X-ray crystallography to decipher the structural basis of inhibition of TRIM25 activity by NS1 and the structural differences between NS1-TRIM25 complexes of H5N1 and H1N1.

List of Research Outputs

Graeff R., Liu Q., Kriksunov I.A., Kotaka M., Oppenheimer N., Hao Q. and Lee H.C., Mechanism of Cyclizing NAD to Cyclic ADP-ribose by ADP-ribosyl Cyclase and CD38, Journal of Biological Chemistry. 2009, 284: 27629-27636.

Kotaka M., Dutta S., Lee H.C., Lim M.J., Wong Y., Rao F., Mitchell E.P., Liang Z.X. and Lescar J., Expression, purification and preliminary crystallographic analysis of Pseudomonas aeruginosa RocR protein., Acta crystallographica. Section F, Structural biology and crystallization communications. England, Wiley-Blackwell, 2009, 65: 1035-8.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Croucher ASI 2009 "Structure-based screening and design of ligands for protein targets". 2009.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Joint Meeting of the HK Society of Neurosciences and the Biophysical Society of Hong Kong. 2010.

Lam W.W., Woo E.J., Kotaka M., Tam W.K., Leung Y.C., Ling T.K. and Au S.W., Molecular interaction of flagellar export chaperone FliS and cochaperone HP1076 in Helicobacter pylori. , FASEB journal. 2010, 24: 4020-32.

Researcher : Kravtsov GM

List of Research Outputs

Tang W.H., Cheng W.T., Kravtsov G.M., Tong X.Y., Hou X.Y., Chung S.K. and Chung S.S.M., Cardiac contractile dysfunction during acute hyperglycemia due to impairment of SERCA by polyol pathway-mediated oxidative stress, American Journal of Physiology and Cell Physiology. 2010, 299: C643-C653.

Tang W.H., Kravtsov G.M., Sauert M., Tong X.Y., Hou X.Y., Wong T.M., Chung S.K. and Chung S.S.M., Polyol pathway impairs the function of SERCA and RyR in ischemic-reperfused rat hearts by increasing oxidative modificaitons of these proteins, Journal of Molecular and Cellular Cardiology. 2010, 49: 58-69.

Yeung H.M., Hung M.W., Kravtsov G.M. and Fung M.L., Chronic intermittent hypoxia exacerbates oxidative stress and deteriorates calcium homeostasis in rat hearts. 63^rd High Blood Pressure Research Conference, American Heart Association, USA 9/2009.

Researcher : Lai CH

List of Research Outputs

Chu J.Y.S., Lee T.O., Lai C.H., Vaudry H., Chan Y.S., Yung W.H. and Chow B.K.C., Secretin as a neurohypophysial factor regulating body water homeostasis, Proceedings of National Academy of Sciences,USA. 2009, 106: 15961-15966.

Han L., Lai S.K., Lai C.H. and Chan Y.S., Electrophysiological study of synaptic transmission in inferior olivary neurons of postnatal rats, Society Neuroscience Abstract (USA) . 2009, 812.5/B37.

Hu H., Lai S.K., Lai C.H. and Chan Y.S., Developmental profile of inhibitory synaptic transmission in medial vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.8/B63.

Lai C.H., Yiu N.S.C., Lai S.K., Ng K.P., Yung K.K., Shum D.K.Y. and Chan Y.S., Maturation of canal-related brainstem neurons in the detection of horizontal angular acceleration in rats, Journal of Comparative Neurology. 2010, 518: 1742-1763.

Lai S.K., Lai C.H., Wong T.P., Yung W.H. and Chan Y.S., Developmental regulation of ionotropic glutamate receptors in central vestibular neurons in rats, The 32^nd Annual Meeting of the Japan Neuroscience Society. 2009.

Lau Y.P., Lai C.H. and Chan Y.S., Developmental responsiveness of thalamic neurons to vertical sinusoidal linear acceleration, Society Neuroscience Abstract (USA). 2009, 813.5/B53.

Ma C.W., Lai C.H., Lai S.K., Tse Y.C., Yung K.K., Shum D.K.Y. and Chan Y.S., Developmental distribution of vestibular nuclear neurons responsive to different speeds of horizontal translation, Brain Research. 2010, 1326: 62-67.

Ma C.W., Lai C.H., Chan Y.S. and Shum D.K.Y., In vitro and in vivo studies of perineuronal glycosaminoglycans in synaptic functions, Society Neuroscience Abstract (USA) . 2009, 719.10/D6.

Ng K.P., Lai C.H. and Chan Y.S., Postnatal NMDA receptor blockade alters the characteristics of canal-related inferior olivary neurons, Society Neuroscience Abstract (USA) . 2009, 813.15/B63.

Ng K.P., Han L., Lau P.Y.P., Li C., Lai C.H., Shum D.K.Y. and Chan Y.S., Postnatal refinement of gravity-related spatial coding to the central vestibular circuitry, J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences. Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 204.

Researcher : Lai SK

Project Title:	Ionotropic glutamate receptors are essential to the maturation of central vestibular neurons of rats
Investigator(s):	Lai SK, Chan YS
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	09/2008
Completion Date:	02/2010

Abstract:

Glutamate is a major neurotransmitter in the mature vestibular nucleus. In rats, stimulation of the vestibular nerve evoked ionotropic glutamate receptor-mediated excitatory transmission in the vestibular nucleus (15, 16). There are two types of ionotropic glutamate recpetors, -amino-3-hydroxyl-5-isoxazole-propionic acid, AMPA and N-methyl-D-aspartate, NMDA: AMPA receptors (AMPAR) mediate fast voltage-independent synaptic responses whereas NMDA receptors (NMDAR) mediate slow voltage-dependent synaptic responses. The latter is implicated in multiple forms of developmental and activity-dependent synaptic plasticity, including long-term potentiation (LTP). The functional properties of ionotropic glutamate receptors are determined by their subunit composition (3, 10). However, the contribution of AMPAR and NMDAR subunits to the functional maturation of central vestibular neurons, particularly in the development of spatial recognition, is poorly understood. Preliminary findings of our laboratory showed that the rat vestibular system is not mature at birth. Behavorial data obtained from negative geotaxis test demonstrated that rats could not re-orient from an ear-down (transverse orientation) to a nose-up position until postnatal day 7 (P7) and from a nose-down (antero-posterior orientation) to a nose-up position until P9. Both immunohistochemical and in vivo electrophysiological data showed that otolith-related vestibular nuclear neurons were responsive to head movements from P7 onwards but did not show adult characteristics until the third postnatal week (7, 8, 9). Whole-cell patch clamp experiments in rat brainstem slices further demonstrated that NMDAR-mediated current dominated before P5 while AMPAR-mediated current dominated after P7. Our immunohistochemical data also demonstrated differential expression profiles of ionotropic glutamate receptor subunits during postnatal development (17). Thus, in the developing vestibular nucleus, differential recruitment of AMPAR and NMDAR subunits may fine-tune the properties of voltage-gated ion channels. We therefore hypothesize that the maturation of vestibular nuclear neurons depends on the expression of function of glutamate receptor subunits in the synapse. In the forebrain, NMDAR-only synapses are functionally silent due to the presence of Mg2+ blockade; this occurs early in development but converts to fast-signaling, functional synapses with the recruitment of AMPARs and thus the expression of LTP (1, 4, 6). This conversion allows the establishment of appropriate synaptic connections during maturation of the neural circuitry (6). The corollary suggests that occurrence of LTP can be taken as an indicator of the conversion. Although silent synapses have been widely investigated in the cortex and hippocampus, the involvement of silent synapses or LTP-like mechanism in the development of vestibular function remains unknown. In early postnatal rats, immunohistochemical studies indicated that AMPARs in immature vestibular nuclear neurons mainly consist of GluR1 and GluR4 receptor subunits (13, 14). In other central neurons, these subunits are known to contribute to high Ca2+ influx (18). We hypothesize therefore that the expression of GluR1/4 receptor subunits and their recruitment to silent synapses are crucial to functional maturation of the vestibular neuronal circuit. NMDA receptors are heteromeric, consisting of at least one NR1 subunit and up to four NR2 subunits. The composition of NR2 subunits is developmentally regulated (5, 11, 12). In the neonatal cortex and hippocampus of rats, NR1/NR2B subunits dominate in immature glutamatergic synapses, coincident with a low AMPAR/NMDAR ratio (2, 4). During synapse formation, NR2B subunits are known to stabilize NMDARs at postsynaptic sites and guide AMPARs into functional synapses. Studies in the adult forebrain have shown that NMDARs containing NR2A subunits are required for LTP whereas those with NR2B subunits are for long-term depression (1,2,5). In the immature forebrain, however, NMDAR-only synapses containing NR2B subunits induce LTP (1,2). Our preliminary data from whole-cell patch clamp experiments in rat vestibular nuclear neurons showed that NR2B subunits dominated before P5 and progressively shifted to NR2A subunits after the first postnatal week. These findings suggest that NR2B subunits are also crucial to the development of vestibular function. We hypothesize that blockade of NR2B subunit in the developing vestibular nucleus perturbs synaptic plasticity and hinders the maturation of vestibular function. The first aim of the present study is to determine LTP as indicator of the maturation of glutamatergic synapses within the vestibular nucleus. Experiments will be conducted in brainstem slice preparations containing the vestibular nucleus to find (i) the onset of LTP in the course of postnatal development, and (ii) the subunit involvement that induces the postnatal elicitation of LTP. Neonatal blockade of GluR1 receptor subunit or NR2B receptor subunit by specific antagonist(s) will be attempted to prevent the elicitation of LTP at postnatal stages when LTP is normally expressed. The second aim of this study is to investigate the effect of blocking LTP in vestibular nuclear neurons on the maturation of vestibular functions as assessed by behavioral tests.

List of Research Outputs

Han L., Lai S.K., Lai C.H. and Chan Y.S., Electrophysiological study of synaptic transmission in inferior olivary neurons of postnatal rats, Society Neuroscience Abstract (USA) . 2009, 812.5/B37.

Hu H., Lai S.K., Lai C.H. and Chan Y.S., Developmental profile of inhibitory synaptic transmission in medial vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.8/B63.

Lai C.H., Yiu N.S.C., Lai S.K., Ng K.P., Yung K.K., Shum D.K.Y. and Chan Y.S., Maturation of canal-related brainstem neurons in the detection of horizontal angular acceleration in rats, Journal of Comparative Neurology. 2010, 518: 1742-1763.

Lai S.K., Lai C.H., Wong T.P., Yung W.H. and Chan Y.S., Developmental regulation of ionotropic glutamate receptors in central vestibular neurons in rats, The 32^nd Annual Meeting of the Japan Neuroscience Society. 2009.

Lai S.K., Tse Y.C., Hu H., Wong T.P., Yung W.H. and Chan Y.S., Maturation profile of inhibitory and excitatory postsynaptic currents in central vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.14/B62.

Ma C.W., Lai C.H., Lai S.K., Tse Y.C., Yung K.K., Shum D.K.Y. and Chan Y.S., Developmental distribution of vestibular nuclear neurons responsive to different speeds of horizontal translation, Brain Research. 2010, 1326: 62-67.

Tao K.P., Lai S.K., Chan Y.S., Sham M.H. and Chan S.Y., Tspyl2 is involved in Cellular Stress Response and Brain Function, 14^th Research Postgraduate Symposium, HKU, 2-3 December 2009.

Tsang K.H., Lai S.K., Chan Y.S. and Chan S.Y., Testis-specific Protein Y-linked-Like 2 (Tspyl2) Regulates Hippocampal Long-term Potentiation via NMDA Receptors Expression and p38MAPK Activity, 14^th Research Postgraduate Symposium, HKU, 2-3 December 2009.

Tsang K.H., Tao K.P., Lai S.K., Chan Y.S. and Chan S.Y., Tspy12 regulates hippocampal long-term potentiation via NMDA receptor subunits Nr2a and Nr2b expression, 43^rd Annual Meeting for the Japanese Society of Developmental Biologists (Jointly sponsored by the Asia-Pacific Developmental Biology Network), Japan, 20-23 June 2010.

Researcher : Lam MC

Project Title:	Characterization of cyclic ADP-ribose-mediated chemotactic response in monocytes
Investigator(s):	Lam MC, Lee HC
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	09/2008
Completion Date:	08/2009

Abstract:

Immunocytes plays an important role in the immune response against infection and infection-induced inflammation. During inflammation, the first wave of neutrophils migration to the affected tissue is followed by a second wave of monocytes [1]. While upon chronic inflammation, monocytes are indeed the main effector cells where neutrophils may not be present. Monocytes infiltration is believed to go through the following steps: (1) adhering to the blood vessel endothelium and then (2) transmigration following the chemical cues [2]. Recent findings suggest cyclic ADP-ribsose (cADPR), a universal calcium mobilizer for intracellular Ca2+ stores, differentially regulate chemoattractant receptors expressed in monocytes [3], however the exact mechanisms about cADPR-mediated chemotactic migration are not yet determined. cADPR is widespread in many different cell types and species, including protozoans, plants, and animals [4]. cADPR is generated by ADP-ribosyl cyclases from nicotinamide adenine dinucleotide (NAD+). CD38, a multi-functional enzyme and a type II transmembrane protein, is the predominant form of ADP-ribosyl cyclase in mammalian cells. CD38 is expressed constitutively on natural killer cells and resting monocytes [5], but only activated lymophocytes are CD38+ [6]. Differences in cellular expression of CD38 reflect its multi-functional roles in immune cells. Recent studies on CD38 deficient-mice demonstrated that cADPR produced by CD38 are essential for immune responses in vivo [7]. CD38 knockout-mice, which lacking CD38 in their neutrophils, are susceptible to bacterial infections due to defects in chemotactic migration [7]. A recent study suggested that N-formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived chemotactic peptide, stimulate Ca2+ increase and migration of human neutrophils which can be blocked by cell permeable cADPR antagonist [8]. Despite many aspects of chemotactic response have been elucidated in neutrophils [7-10], little is known about the mechanisms of cADPR-mediated chemotactic migration, and especially in monocytes. This proposal is aimed to elucidate the signaling mechanisms involved in cADPR-mediated chemotactic migration by characterizing the components involved. The specific aims are as follow: 1. To investigate whether cADPR induced calcium release from ryanodine-sensitive Ca2+ stores is involved in cADPR-mediated chemotactic migration. 2. To study the role of CD38 in cADPR-mediated chemotactic migration.

List of Research Outputs

Yue J., Wei W., Lam M.C., Zhao Y., Zhang L.R., Zhang L.H. and Lee H.C., The CD38/cADPR/Ca2+-pathway promotes cell proliferation and delays NGF-induced differentiation in PC12 cells. , Journal of Biological Chemistry . 2009, 284: 29335-29342.

Researcher : Lau CF

List of Research Outputs

Lau C.F., Ng K.M., Tipoe G.L. and Fung M.L., Chronic intermittent hypoxia induces oxidative stress and decreases NO production in the carotid artery of rats. The 13^th Annual Scientific Meeting of the Institute of Cardiovascular Science and Medicine, P16, 12/2009, (Journal of the Hong Kong College of Cardiology). 2009, 17(2):61.

Lau C.F., Hung M.W., Ng K.M., Tipoe G.L. and Fung M.L., Oxidative injury and inflammation in the lung of rats exposed to chronic intermittent hypoxia, Physiology Symposium 2009, HKU,Hong Kong 5/2009.

Lau C.F., Ng K.M. and Fung M.L., Oxidative stress and inflammation are involved in the endothelial dysfunction of rat carotid artery in chronic intermittent hypoxia, The Fifth International Symposium on Healthy Aging, HKU, Hong Kong, 3/2010.

Lin R., Lau C.F., Wang J., Ni Y., Fung M.L. and Huang J., Reduced neuronal nitric oxide production in KIF5b-deficiency mice, 2010 Hong Kong Inter-University Biochemistry Postgraduate Symposium, CUHK, Hong Kong, 15 May,. 2010.

Liu Y., Lau C.F., Ng K.M. and Fung M.L., Up-regulated eNOS expression and NO production in rat adrenal gland in chronic hypoxia, Physiology Symposium 2009, HKU, Hong Kong 5/2009.

Researcher : Lau PYP

List of Research Outputs

Ng K.P., Han L., Lau P.Y.P., Li C., Lai C.H., Shum D.K.Y. and Chan Y.S., Postnatal refinement of gravity-related spatial coding to the central vestibular circuitry, J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences. Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 204.

Researcher : Lau YP

List of Research Outputs

Lau Y.P., Lai C.H. and Chan Y.S., Developmental responsiveness of thalamic neurons to vertical sinusoidal linear acceleration, Society Neuroscience Abstract (USA). 2009, 813.5/B53.

Researcher : Lee HC

Project Title:	A calcium-signaling pathway mediated by cyclic ADP-ribose and NAADP
Investigator(s):	Lee HC
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	08/2007

Abstract:

(1) Elucidate the catalytic mechanism of CD38; (2) Determine the membrane polarity of CD38 in cells.

Project Title:	Chemical synthesis and biological characterizations of antagonists of a novel calcium signaling enzyme - CD38
Investigator(s):	Lee HC
Department:	Physiology
Source(s) of Funding:	NSFC/RGC Joint Research Scheme
Start Date:	01/2009

Abstract:

To chemical synthesize a series of specific antagonists of CD38; to characterize the antagonists enzymologically and physiologically; to determine the structures of CD38/antagonist complexes by X-ray crystallography.

Project Title:	Systemic modulation of cardiovascular functions by a Ca2+ messenger - Cyclic ADP-ribose
Investigator(s):	Lee HC, Wong TM
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	01/2009

Abstract:

(1) To establish the hypotensive action of cADPR in anesthetized rats; (2) To delineate the signaling mechanisms mediating the vasodilating action of cADPR.

Project Title:	Structure and Function of the ADP-ribosyl Cyclases.
Investigator(s):	Lee HC, Hao Q, Li GR
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	01/2010

Abstract:

To elucidate the catalytic mechanisms of the ADP-ribosyl cyclases by site-directed mutagenesis and X-ray crystallography.

List of Research Outputs

Graeff R., Liu Q., Kriksunov I.A., Kotaka M., Oppenheimer N., Hao Q. and Lee H.C., Mechanism of Cyclizing NAD to Cyclic ADP-ribose by ADP-ribosyl Cyclase and CD38, Journal of Biological Chemistry. 2009, 284: 27629-27636.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Croucher ASI 2009 "Structure-based screening and design of ligands for protein targets". 2009.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Joint Meeting of the HK Society of Neurosciences and the Biophysical Society of Hong Kong. 2010.

Liu Q., Graeff R., Kriksunov I.A., Jiang H., Zhang B., Oppenheimer N., Lin H., Potter B.V.L., Lee H.C. and Hao Q., Structural Basis for Enzymatic Evolution from a Dedicated ADP-ribosyl Cyclase to a Multifunctional NAD Hydrolase, Journal of Biological Chemistry. 2009, 284: 27637-27645.

Yue J., Wei W., Lam M.C., Zhao Y., Zhang L.R., Zhang L.H. and Lee H.C., The CD38/cADPR/Ca2+-pathway promotes cell proliferation and delays NGF-induced differentiation in PC12 cells. , Journal of Biological Chemistry . 2009, 284: 29335-29342.

Researcher : Leung CFP

Project Title:	Regulation of CD38 in abscisic acid-activated human monocytes.
Investigator(s):	Leung CFP, Lee HC
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	09/2009

Abstract:

Abscisic acid (ABA) is a phytohormone mediating many fundamental processes in higher plants including response to abiotic stress [1,2]. Endogenous ABA biosynthesis occurs also in lower Metazoa, in which ABA regulates several physiological functions. The mechanism of ABA-signaling has recently been shown to involve activation of ADP-ribosyl cyclase (ADPRC), resulting in increase of the Ca2+-mobilizing second messenger cyclic ADP-ribose (cADPR), and elevation of intracellular Ca2+ concentration ([Ca2+]i). Recently, production and release of ABA have been demonstrated to take place also in human granulocytes, where ABA behaves as a proinflammatory hormone through a signaling pathway involving a pertussis toxin (PTX)-sensitive receptor/G protein complex, activation of adenylyl cyclase, cAMP production, PKA-mediated phosphorylation of the ADP-ribosyl cyclase CD38, and the increase of the intracellular concentration of cADPR [3]. The ABA-induced [Ca2+]i rise then induces production of reactive oxygen species (ROS) and nitric oxide release, cumulating in stimulation of chemotaxis of the granulocytes toward regions of higher ABA concentration. ABA is thus not only a phytohormone in plants, but also is emerging as a new endogenous proinflammatory hormone in human [4,5]. Monocytes are the primary inflammatory cell type that infiltrates early atherosclerotic plaques. At the site of atherosclerotic lesion, monocytes/macrophages, platelets and endothelial cells release chemoattractants, growth factors and cytokines, which stimulate vascular smooth muscle cells (VSMC) to proliferate and migrate into the sub-endothelium. Thrombus organization, extracellular matrix synthesis and VSMC proliferation eventually lead to the development of the atheromatous plaques [6,7]. cADPR is formed from nicotinamide adenine dinucleotide (NAD) by ADP-ribosyl cyclases. Six ADP-ribosyl cyclases have been identified including Aplysisa ADP-ribosyl cylcase [8], three sea urchin homologues [9], two mammalian homologues, (CD38 and CD157) [10]. Human CD38 is a type II transmembrane glycoprotein containing a small N-terminal tail, a single transmembrane helix, and a large extra-membranous portion that possesses ADP ribosyl cyclase activity. As a member of the cyclase family, CD38 not only can synthesize cADPR from NAD+ but also can hydrolyze NAD+ and cADPR to produce ADP-ribose. In addition to its cADPR-synthesizing activity, CD38 is in fact the only characterized enzyme that can effectively degrade cADPR [11-15]. At acidic conditions, CD38 can also catalyze the formation and hydrolysis of NAADP, another calcium mobilization messenger [16]. Studies using knock-out mice have established that CD38 is the major mammalian enzyme responsible for regulating endogenous levels of cADPR [17]. Multiple defects have been seen in the knock-out mice, indicating the important roles of CD38 in regulating physiological functions [18-21]. To better understand the CD38/cADPR-dependent calcium signaling, it is important to know the structural determinants and molecular interactions involved in the synthesis and hydrolysis of cADPR catalyzed by CD38. We have previously obtained the structure of a CD38-cADPR complex by using a catalytically inactive mutant of CD38 [22]. This was performed by mutating the catalytic residue Glu-226 to glutamine (Q), and the inactive mutant (E226Q) was used to form a complex with cADPR [22]. This has allowed detailed delineation of exactly how the substrate interacts with the active site at atomic resolution [22]. This proposal is aimed to elucidate (1) the role of cADPR in mediating the ABA-signaling in human monocytes and (2) how CD38, its synthesis enzyme, is regulated in during ABA-induced activation of the human monocytes.

List of Research Outputs

Chan Y.C., Leung C.F.P., Wong W.T., Tian X.Y., Yung L.M., Lau C.W., Tsang S.Y., Yao X., Chen Z.Y. and Huang Y., Therapeutically relevant concentrations of raloxifene dilate pressurized rat resistance arteries via calcium-dependent endothelial nitric oxide synthase activation., Arterioscler Thromb Vasc Biol. 2010, 30(5): 992-9.

Researcher : Li C

List of Research Outputs

Ng K.P., Han L., Lau P.Y.P., Li C., Lai C.H., Shum D.K.Y. and Chan Y.S., Postnatal refinement of gravity-related spatial coding to the central vestibular circuitry, J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences. Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 204.

Researcher : Li L

List of Research Outputs

Li L., Tang F. and O W.S., Adrenomedullin in rat corpus luteum and its role in steroidogenesis during pregnancy, Biology of Reproduction. 2009, 81: 542.

Li L., Hwang I.S.S., Tang F., O W.S. and Li Y.Y., Coexpression of adrenomedullin and its receptors in the reproductive system of the rat: effects on sterold secretion in rat ovary, Yakhteh Medical Journal. 2009, 11(1): 36.

O W.S., Li L., Cheung M.P.L. and Tang F., The role of adrenomedullin in embryo implantation in the rat, The First State Key Laboratory of Reproductive Biology on Frontiers in Perrimplantation Biology. 2010, 60.

Researcher : Li M

List of Research Outputs

Li M., Chan Y.S. and Shum D.K.Y., Chondroitin sulfate moieties expressed by migrating motor neurons in explant cultures of the rat hindbrain, Proceedings of 32nd Annual Meeting of Japan Neuroscience Society . 2009, P1-e10.

Li M., Chan Y.S. and Shum D.K.Y., Expression of chondroitin sulfotransferases in cranial motor neurons in the embryonic rat hindbrain, Neuroscience Bulletin (Suppl 1). [8^th Biennial Conference of Chinese Society for Neuroscience. Guangzhou. Nov. 7-10, 2009]. 2009, 25: 113.

Researcher : Li YY

List of Research Outputs

Li L., Hwang I.S.S., Tang F., O W.S. and Li Y.Y., Coexpression of adrenomedullin and its receptors in the reproductive system of the rat: effects on sterold secretion in rat ovary, Yakhteh Medical Journal. 2009, 11(1): 36.

Researcher : Liu Y

List of Research Outputs

Liu Y. and Fung M.L., Chronic hypoxia induces oxidative stress and local inflammation in rat adrenal medulla, 14^th Research Postgraduate Symposium, HKU, P1.18, 12/2009.

Liu Y. and Fung M.L., Chronic intermittent hypoxia induces oxidative stress and local inflammation in rat adrenal medulla , The Fifth International Symposium on Healthy Aging, HKU, Hong Kong 3/2010.

Liu Y. and Fung M.L., Oxidative stress and local inflammation in rat adrenal medulla in chronic hypoxia. The 13^thAnnual Scientific Meeting of the Institute of Cardiovascular Science and Medicine 12/2009, (Journal of the Hong Kong College of Cardiology). 2009, 17(2):61: 15.

Liu Y., Lau C.F., Ng K.M. and Fung M.L., Up-regulated eNOS expression and NO production in rat adrenal gland in chronic hypoxia, Physiology Symposium 2009, HKU, Hong Kong 5/2009.

Researcher : Lung MAKY

Project Title:	Endothelins in nasal mucosa: role in nasal congestion and decongestion
Investigator(s):	Lung MAKY
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2004

Abstract:

To investigate the role of endothelins on the nasal mucosa, eliciting nasal congestion or decongestion, as well as the underlying vascular events and control mechanisms.

Project Title:	Muscarinic receptor subtypes in the control of nasal patency
Investigator(s):	Lung MAKY
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2006

Abstract:

Rhinitis, affecting about 20% of the world population and with increasing prevalence worlwide, is characterized by symptoms of mucosal hypereamia, engorgement, rhinorrea and nasal obstruction. In vivo studies in dogs show that acetylcholine induces nasal congestion at low doses (Lung & Wang, Ann Otol Rhinol Laryngol 1994; 103:646-651). Recent in vitro studies confirm that acetylcholine at low concentrations relaxes posterior collecting veins but contracts other collecting and outflow veins (Wang & Lung, Eur Resp J published online on May 31, 2006 as 10.1183/09031936.06.00077105). According to the vascular arrangements of the nasal mucosa, activation of muscarinic receptors in the posterior collecting veins will increase vascular capacitiance while activation of muscarinic receptors in the outflow veins will impair venous drainage. Both mechanisms acting together can easily promote nasal congestion especially when the number and reactivity of the mucarinic receptors are increased. An increase in the number of muscarinic receptors has been found in the nasal mucosa of human or animal models with nasal allergy (Naminatsu et al, Jpn J Pharmacol 1992; 59: 427-437). Radiolabelled ligand binding, autoradiography, competitive binding analysis and imumological studies suggest that M1, M2 and M3 receptor subtypes are present in the sinusoidal venous vessels of human inferior turbinate mucosa and among them M3 receptors are the most extensively distributed (Nakaya et al., Ann Otol Rhinol Laryngol 2002; 111: 593-597). However, the presence and distribution of muscarinci receptor subtypes in the collecting and outflow veins of the nasal mucosa are still unknown. The objective of this project is to to investigate the functional role of muscarinic receptors in the control of nasal patency. To achieve this, we will 1. perform in vivo functional studies to characterize the muscarinic receptor subtypes present on the resistance and and capacitance vessels and to define their individual role in the control of nasal vascular and airway resistances. 2. perform in vitro studies to characterize the muscarinic receptors present on the nasal collecting and outflow veins and to define their individual role in the control of airway resistance. 3. perform immunohistochemical studies on the localization of muscarinic subtype receptors (M1, M2 and M3) as to confirm their presence and distribution in the nasal vasculature.

Project Title:	Expression of adrenomedullin and its receptors in nasal vascular bed
Investigator(s):	Lung MAKY
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2007

Abstract:

Nasal obstruction, one of the cardinal signs of rhinitis, is commonly believed be due to blood congestion in the venous sinusoids of the nasal mucosa. Anteriorly venous blood is drained via the high-pressure and high-flow dorsal nasal vein while posteriorly via the low-pressure and low-flow sphenopalatine vein. The collecting and outflow veins of both systems are large and highly muscular in nature. Since the collecting veins are located within the nasal cavity, their dilatation can increase considerably mucosal blood volume. The outflow veins are situated outside the nasal cavity and their dilatation will favor venous outflow. Mucosal congestion, thereby nasal obstruction, may be related not only to the dilatation of the resistances vessels but also dilatation of venous sinusoids and/or collecting veins. However, dilatation of the outflow veins will cause mucosal decongestion (Lung & Wang, 1987, J. Physiol. 391: 57-70; Lung & Wang, 1989, J. anat. 166: 113-119). Adrenomedullin is a 52-amino-acid peptide originally isolated from extracts of human pheochromocytoma. The peptide is widely synthesized and secreted from most cells of the body, including endothelial cells and vascular smooth muscle cells. The peptide has multiple regulatory functions, the most distinctive of which is its vasodilatatory effect. The dilatatory action is exerted via activation of adrenomedullin receptors (L1 and CRLR). The secretion of adrenomedullin is raised in various experimental and clinical infections as well as inflammatory conditions, implying that the peptide may have important roles in the pathphysiology of inflammatory response in addition to those for the regulation of vascular tone (Nishikimi, 2005, Adrenomedullin in Cardiovascular Disease, Springer). Adrenomedullin, being a potent vasodilator, is a highly potential nasal congestant if it acts on the resistance vessel and/or sinusoidal venous plexuses and collecting veins of the nasal vascular bed. However, the peptide can be a decongestant if it acts more prominently on the nasal outflow veins. Although the peptide has been found to induce vasodilatation in many different vascular beds, such as cerebral, coronary, pulmonary, renal and retinal blood vessels, its influence on the nasal circulation has never been investigated. It is not known whether adrenomedullin is being synthesized or whether adrenomedullin receptors are present in the nasal blood vessels for executing its potent vasodilatatory action. The objective of this project is to perform immunohistochemical studies on the expression of adrenomedullin and its receptors in both arterial (sphenopalatine artery) and various venous segments (sinusoidal venous plexuses, collecting veins and outflow veins) of the nasal vascular bed.

Researcher : Lung MKY

Project Title:	Endothelins in nasal mucosa: role in nasal congestion and decongestion
Investigator(s):	Lung MAKY
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2004

Abstract:

To investigate the role of endothelins on the nasal mucosa, eliciting nasal congestion or decongestion, as well as the underlying vascular events and control mechanisms.

Project Title:	Muscarinic receptor subtypes in the control of nasal patency
Investigator(s):	Lung MAKY
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2006

Abstract:

Project Title:	Expression of adrenomedullin and its receptors in nasal vascular bed
Investigator(s):	Lung MAKY
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2007

Abstract:

Researcher : Ma CW

List of Research Outputs

Cham W.C., Ma C.W., Zhang Y., Xie H., Yung W.H., Chan Y.S. and Shum D.K.Y., The Regulatory Role of Heparanase in Synaptic Plasiticity at Hippocampus, 14th Research Postgraduate Symposium, December 2 & 3, 2009, The University of Hong Kong. 2009.

Cham W.C., Ma C.W., Zhang Y., Xie H., Yung W.H., Chan Y.S. and Shum D.K.Y., The regulatory role of heparanase of synaptic plasticity in hippocampus, Society Neuroscience Abstract (USA). 2009, 318.3/C4.

Ma C.W., Lai C.H., Lai S.K., Tse Y.C., Yung K.K., Shum D.K.Y. and Chan Y.S., Developmental distribution of vestibular nuclear neurons responsive to different speeds of horizontal translation, Brain Research. 2010, 1326: 62-67.

Ma C.W., Lai C.H., Chan Y.S. and Shum D.K.Y., In vitro and in vivo studies of perineuronal glycosaminoglycans in synaptic functions, Society Neuroscience Abstract (USA) . 2009, 719.10/D6.

Ma C.W., Zhang Y., Cham W.C., Chan Y.S. and Shum D.K.Y., Role of heparanase in synaptic plasticity at the hippocampus and vestibular nucleus , J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 145.

Researcher : Ng KM

List of Research Outputs

Lau C.F., Ng K.M., Tipoe G.L. and Fung M.L., Chronic intermittent hypoxia induces oxidative stress and decreases NO production in the carotid artery of rats. The 13^th Annual Scientific Meeting of the Institute of Cardiovascular Science and Medicine, P16, 12/2009, (Journal of the Hong Kong College of Cardiology). 2009, 17(2):61.

Lau C.F., Hung M.W., Ng K.M., Tipoe G.L. and Fung M.L., Oxidative injury and inflammation in the lung of rats exposed to chronic intermittent hypoxia, Physiology Symposium 2009, HKU,Hong Kong 5/2009.

Lau C.F., Ng K.M. and Fung M.L., Oxidative stress and inflammation are involved in the endothelial dysfunction of rat carotid artery in chronic intermittent hypoxia, The Fifth International Symposium on Healthy Aging, HKU, Hong Kong, 3/2010.

Liu Y., Lau C.F., Ng K.M. and Fung M.L., Up-regulated eNOS expression and NO production in rat adrenal gland in chronic hypoxia, Physiology Symposium 2009, HKU, Hong Kong 5/2009.

Ng K.M., Lee Y.K., Chan Y.C., Lai K.W.H., Fung M.L., Li R.A., Siu D.C.W. and Tse H.F., Exogenous expression of HIF-1alpha promotes cardiac differentiation of embryonic stem cells., Journal of Molecular and Cellular Cardiology. 2010, 48(6): 1129-37.

Ng K.M., Lee Y.K., Chan Y.C., Lai W.H.K., Fung M.L., Li R.A., Siu D.C.W. and Tse H.F., Exogenous expression of HIF-1a promotes the cardiac differentiation of embryonic stem cells, Journal of Molecular and Cellular Cardiology. 2010, 48(6): 1129-1137.

Ng K.M., Lee Y.K., Fung M.L., Li R.A., Siu D.C.W. and Tse H.F., Hypoxia promotes cardiac differentiation of human embryonic stem cells, Physiology Symposium 2009, HKU, Hong Kong 5/2009.

Researcher : Ng KP

List of Research Outputs

Lai C.H., Yiu N.S.C., Lai S.K., Ng K.P., Yung K.K., Shum D.K.Y. and Chan Y.S., Maturation of canal-related brainstem neurons in the detection of horizontal angular acceleration in rats, Journal of Comparative Neurology. 2010, 518: 1742-1763.

Ng K.P., Lai C.H. and Chan Y.S., Postnatal NMDA receptor blockade alters the characteristics of canal-related inferior olivary neurons, Society Neuroscience Abstract (USA) . 2009, 813.15/B63.

Ng K.P., Han L., Lau P.Y.P., Li C., Lai C.H., Shum D.K.Y. and Chan Y.S., Postnatal refinement of gravity-related spatial coding to the central vestibular circuitry, J. Physiological Sciences (Suppl 1). [36^th Int’l Congress of International Union of Physiological Sciences. Kyoto, Japan. July 27 - Aug. 1, 2009]. 2009, 59: 204.

Researcher : Ng KP

List of Research Outputs

Ng K.P., Lai C.H. and Chan Y.S., Postnatal NMDA receptor blockade alters the characteristics of canal-related inferior olivary neurons, Society Neuroscience Abstract (USA) . 2009, 813.15/B63.

Researcher : Pang B

List of Research Outputs

Shiu S.Y.W., Pang B., Tam C.W. and Yao K.M., Involvement of Gas and Gaq proteins in melatonin-induced prostate epithelial cell antiproliferation, XI. Congress of the European Biological Rhythms Society, Strasbourg, France, August 22-28. 2009, S10-5.

Researcher : Shiu SYW

Project Title:	Melatonin signaling in the regulation of prostate and kidney epithelial cell biology
Investigator(s):	Shiu SYW
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2007
Completion Date:	10/2009

Abstract:

Recent studies have indicated that melatonin, a pineal gland neurohormone, exerts antiproliferative effects on different types of cancer. Importantly, we have reported growth-inhibitory actions of melatonin on human prostate cancer cells in culture and in nude mice, and have consistently demonstrated an association between melatonin antiproliferation and MT1 receptor expression in androgen-independent human prostate cancer cells in culture and in tissue xenografts in both intact and castrated nude mice [Xi et al., 2000; Xi et al., 2001; Siu et al., 2002]. Furthermore, administration of melatonin to a castrated prostate cancer patient whose prostate tumor tissue expressed MT1 receptor was found to slow the early biochemical progression, as indicated by serum prostate-specific antigen (PSA) level changes, of his hormone-refractory tumor [Shiu et al., 2003]. This proof-of-concept translational study in a human subject provided strong support for MT1 receptor to play a key role in mediating the direct antiproliferative prostate tumor suppressive action of melatonin. Indeed, we have most recently shown that the antiproliferative effect of melatonin on androgen-independent prostate cancer cells was effected by up-regulation of the tumor suppressor p27Kip1 protein through MT1-receptor mediated activation of both protein kinase C (PKC) and protein kinase A (PKA) [Tam et al., 2007]. Based on our observations, we would like to test whether this novel signaling pathway also operates in benign prostate epithelial cells as well as in other non-malignant cells of the urogenital system such as the kidney epithelial cells. Furthermore, we propose to identify the G proteins that are specifically coupled to MT1 receptor in this novel antiproliferative signaling pathway that has been discovered by us.

Project Title:	Transcriptional regulation of p27Kip1 by melatonin in prostate epithelial cells
Investigator(s):	Shiu SYW
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2008

Abstract:

Prostate cancer is a major public health problem of elderly men in developed countries. Nowadays, most of the cancer deaths arise from the progression of advanced or metastatic tumor cells from an androgen-dependent state to an androgen-independent or hormone-refractory state, as a result of androgen deprivation (castration) therapy. Hence, there is an unmet clinical need for safe and effective pharmaceuticals that can prevent or slow the development and progression of androgen-independent prostate cancer in castrated patients with advanced or metastatic disease. Melatonin is a circadian and circannual hormone produced and secreted by the pineal gland with biorhythmic modulatory and oncostatic actions. An inverse relationship between melatonin production and human prostate cancer incidence has been shown by epidemiological and clinical studies, which supported a potential prostate tumor suppressive function of melatonin. Importantly, the circumstantial evidence provided by epidemiological and clinical studies was corroborated by our laboratory and clinical investigations. Of note, we demonstrated MT1 receptor expression in human prostate cancer tissues, and showed the association of MT1 receptor expression with the antiproliferative action of melatonin in cellular and animal models of androgen-independent prostate cancer [Xi et al. J Pineal Res 2000; 29: 172-183; Xi et al. Prostate 2001; 46:52-61; Siu et al. Prostate 2002; 52: 106-122]. Subsequent administration of melatonin to a castrated prostate cancer patient, whose prostate tumor tissue expressed MT1 receptor, was found to slow the early biochemical progression, as indicated by serum prostate-specific antigen (PSA) level changes, of his hormone-refractory tumor [Shiu et al. J Pineal Res 2003; 35: 177-182]. This proof-of-concept translational study in a human subject thus provided strong support for MT1 receptor to play an important role in mediating the direct antiproliferative prostate tumor suppressive action of melatonin. Recently, we identified a novel signaling mechanism involved in melatonin-induced antiproliferation of hormone-refractory prostate cancer and transformed prostate epithelial cells. Activation of MT1 receptor by melatonin inhibits the proliferation of hormone-refractory prostate cancer 22Rv1 cells and transformed prostate epithelial RWPE-1 cells by up-regulating p27Kip1 gene and protein expression through activation of protein kinase A (PKA) and protein kinase C (PKC) in parallel [Tam et al. J Pineal Res 2007; 42: 191-202; Tam et al. J Pineal Res 2008]. Together, our laboratory and clinical data suggest that melatonin may act as a negative mitogenic hormonal regulator of human prostate epithelial cell growth [Tam et al. J Pineal Res 2008]. While further studies are needed to substantiate a physiological role of melatonin as a human prostate growth suppressor, there are also existing gaps to be filled in the MT1/ PKA+PKC/ p27Kip1 pathway, which we have defined so far in benign RWPE-1 and malignant 22Rv1 prostate epithelial cells. Presently, the most important research goal is to identify the melatonin-regulated transcription factor responsible for increased tumor suppressor p27Kip1 expression in prostate epithelial cell antiproliferation. Towards achieving this goal, we propose in the present study to map the potential DNA binding sequence of the to-be-identified transcription factor within the p27Kip1 promoter that will drive p27Kip1 gene expression when prostate epithelial cells are stimulated by melatonin or by simultaneous PKA and PKC activation.

Project Title:	XI. Congress of the European Biological Rhythms Society Involvement of Gαs and Gαq proteins in melatonin-induced prostate epithelial cell antiproliferation
Investigator(s):	Shiu SYW
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	08/2009
Completion Date:	08/2009

Abstract:

N/A

Project Title:	Growth-modulatory effects of the melatonin receptor agonist ramelteon on prostate epithelial cells
Investigator(s):	Shiu SYW
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	12/2009

Abstract:

In 2007, scientists of the WHO International Agency for Research on Cancer commented that shift work involving circadian disruption is a Group 2A carcinogen (probably carcinogenic to humans) [Straif et al. Lancet Oncol 2007; 8: 1065-1066]. Indeed, epidemiological studies have shown increased risks of breast and prostate cancer in individuals exposed to chronodisruption. It is believed that an important mechanism by which chronodisruption can increase cancer risks is through light-induced suppression of melatonin, a nocturnal hormone secreted by the pineal gland which functions as a circadian and circannual time signal of the body. Indeed, an inverse relationship between melatonin production and human prostate cancer incidence has been demonstrated by epidemiological and clinical studies, which support a potential prostate tumor suppressive function of melatonin. Of note, winter darkness and visual impairment appear to protect, respectively, indigenous Nordic people and the blind from prostate cancer [Prener et al. Acta Oncologica 1996, 35: 589-593; Dewailly et al. Cancer Epidemiol Biomarkers Prev 2003, 12: 926-927; Feychting et al. Epidemiology 1998, 9: 490-494; Pukkala et al. Cancer Causes Control 2006, 17: 573-576]. It is also well known that human melatonin production decreases with age [Waldhauser et al. J Clin Endocrinol Metab 1988, 66: 648-652], and this is associated with increases in prostate cancer incidence with advancing age in elderly men. Moreover, melatonin levels are lower in prostate cancer patients than in patients suffering from benign prostatic hyperplasia [Bartsch C et al. Clin Chim Acta 1992, 209: 153-167]. Importantly, the above-mentioned epidemiological and clinical evidence is strongly corroborated by our laboratory and clinical data [Xi et al. J Pineal Res 2000, 29: 172-183; Xi et al. Prostate 2001, 46:52-61; Siu et al. Prostate 2002, 52: 106-122; Shiu et al. J Pineal Res 2003, 35: 177-182]. Most recently, we identified a novel signaling mechanism involved in melatonin-induced antiproliferation of prostate epithelial cells. Activation of MT1 receptor by melatonin inhibits the proliferation of hormone-refractory prostate cancer 22Rv1 cells and transformed RWPE-1 prostate epithelial cells by up-regulating p27Kip1 gene and protein expression through activation of protein kinase A (PKA) and protein kinase C (PKC) in parallel [Tam et al. J Pineal Res 2007, 42:191-202; J Pineal Res 2008, 45: 403-12]. It is noteworthy that demonstration of this novel melatonin receptor-mediated signaling pathway, namely MT1/ PKA+PKC/ p27Kip1, in two independent epithelial cell lines, which exhibit divergent phenotypes and are derived from the same human peripheral tissue (prostate gland), indicate the potential significance of this melatonin receptor-mediated signaling pathway in the regulation of the human prostate epithelial cell growth. Since p27Kip1 down-regulation is a crucial step in the development and maintenance of the malignant proliferative prostatic epithelial cell phenotype [Fernández et al. J Pathol 1999, 187: 563-566], we believe that melatonin and melatonin receptor agonists hold great promise for prostate cancer prevention and treatment through this melatonin receptor-mediated mechanism of p27Kip1 transcriptional up-regulation. As a result, we would like to study any effects and associated signaling mechanisms of the recently developed melatonin receptor agonist ramelteon, (S)-N-[2-(1,6,7,8-tetrahydro-2H-indeno-[5,4-b]furan-8-yl)ethyl]propionamide, on human prostate epithelial cell growth. There are three research questions that we would like to address in this proposal: • Does ramelteon, like melatonin, inhibit the growth of prostate epithelial RWPE-1 and 22Rv1 cells? • If ramelteon inhibits the growth of prostate epithelial cells, does it act via MT1/PKA+PKC/ p27Kip1 antiproliferative signaling pathway? • Are the antiproliferative actions of ramelteon and melatonin on prostate epithelial cells androgen receptor-dependent and what is the possible mechanism involved?

List of Research Outputs

Shiu S.Y.W., Involvement of Gas and Gaq proteins in melatonin-induced prostate epithelial cell antiproliferation, XI. Congress of the European Biological Rhythms Society, Strasbourg, France. 2009.

Shiu S.Y.W., Pang B., Tam C.W. and Yao K.M., Involvement of Gas and Gaq proteins in melatonin-induced prostate epithelial cell antiproliferation, XI. Congress of the European Biological Rhythms Society, Strasbourg, France, August 22-28. 2009, S10-5.

Shiu S.Y.W., The Time-keeping Hormone Melatonin as a Novel Drug Candidate for the Prevention and Treatment of Prostate Cancer, Fronters in Biomedical Research, LKS Faculty of Medicine, The University of Hong Kong. 2009.

Shiu S.Y.W., The time-keeping hormone melatonin as a novel drug candidate for the prevention and treatment of prostate cancer, Frontiers in Biomedical Research, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, December 4. 2009, p53.

Researcher : Tam CW

List of Research Outputs

Shiu S.Y.W., Pang B., Tam C.W. and Yao K.M., Involvement of Gas and Gaq proteins in melatonin-induced prostate epithelial cell antiproliferation, XI. Congress of the European Biological Rhythms Society, Strasbourg, France, August 22-28. 2009, S10-5.

Researcher : Tang F

Project Title:	Age-related changes in endothelin in the testis and sex accessory glands: peptide level, gene expression and receptor binding
Investigator(s):	Tang F
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	09/2007
Completion Date:	08/2009

Abstract:

Objectives: (1) To study the age-related changes in endothelin-1 (ET-1) and the gene expressionof preproET-1 and its receptor (ETA) in the testis. (2) To study thee age-related changes in ET-1 and the gene expression preproET-1 and ETA receptor in the prostate, seminal vesicle and epididymis. (3) To study the molecular species of ET-1 immunoactivity and receptor binding in the testis. Background. The gene expression of preproET-1 and ETA receptor has been reproted in the testis (Sakurai et al, 1990, 1991). The presence of ET-1 (Matsumoto et al. 1989) and ETA recepor binding (Sakaguchi et al. 1992) has also been confirmed. In the testis, ET-1 decreases blood flow (Collin et al. 1996), stimulates both basal and hCG-stimualted steroidogenesis (Conte et al. 1993) and increaes tubular contraction (Filippini et al 1993). ET- 1 is found in the prostate (Langenstroer et al. 1993), seminal vesicle (Luciano et al. 1995) and the epididymis (Alessandro et al. 1998). It sitmulates amooth muscle contraction via an ETA receptor in the prostate (Angela et al. 2000), seminal vesicle (Luciano et al 1995) and the epididymis (Alessandro et al. 1997). The actions of ET, like those in the testis, are paracrine. In the testis, adrenomedullin (ADM) has the opposite actions as those of ET-1 in blood flow, steroidogenesis and tubular contraction. We have found that ADM increases the synthesis as well as the secretion of ET-1 while ET-1 decreases ADM syntehsis and secretion (Chan et al. 2006) . The gene expression of ADM and its receptors is found to decrease with ageing in 12-month old and 20-month old rats (Tang et al. 2006). Hypothesis: We hypothesize that there may be age-related chagnes in ET-1 and ETA receptor in the testis and the sex accessory glands, which may be related to the decrease in plasma testosterone level and/or testicular ADM. These changes may have important implications for the reproductive functions in the aged subjects in view of the various roles of ET-1 in these organs. Alessandro P, Guido F, Simone G et al. (1997). Clin Endocriol Metab 82: 3797-3806. Alessandro P, Guido F, Simone G et al. (1998). Steroids 63: 294-298. Angela S, Lau WA, Jocelyn N et al. (2000). Eur J Pharmacol 403: 139-145. Chan YF, Tang F, O WS (2006). Abstract P40, Conference of the Society for Reprodcution and Fertility, Leeds, U.K. Collin O, Damber JE, Bergh A (1996). J Reprod Fert 97: 115-121. Conte D, Questino P, Filio S et al. (1993). J Endocrinol 136: R1-4. Filippini A, Tripiciano A, Palombe F et al. (1993). Endcorinology 133: 1789-1796. Langenstroer P, Tang R, Shapiro E et al. (1993) J Urol 149: 495-499. Luciano LG, D'Roleans-Juste P, Calixto J (1995) J Cardiovasc Pharmacol 26 (Suppl. 3): S91-94. Matsumoto H,Suzuki N;, Onda H et al. (1989). Biochem Biophys Res Commun 164: 74-80. Sakaguchi H, Kozuka M, Hirose S et al. (1992). Am J Physiol 263: R15-19. Sakurai T, Yanagisawa M, Inoue A et al. (1991) Biochem Biophys Res Commun 175: 44-47. Sakurai T, Yanagisawa M, Takuwa H et al. (1990). Nature 348: 732-734. Tang F, Li YY, O WS (2006). Abstract P39, Conference of the Society for Reprodcution and Fertility, Leeds, U.K.

Project Title:	Adrenomedullin as a new metabolic hormone: its metabolic actions in the skeletal muscles, adipose tissues and liver, interaction with endothelin and other adipokines, and possible roles in metabolic syndrome.
Investigator(s):	Tang F, Cheung BMY
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	09/2007

Abstract:

To confirm whether adrenomedullin increases or decreases insulin resistance; to study the effects of adrenomedullin on glucose and lipid metbolism in the skeletal muscle, adipose tissue and the liver; to demonstrate changes in the adrenomedullin system in animal models of metbolic syndrome; to show that the use of an adrenomedullin receptor blocker will improve insulin sensivitity; to investigate the mechanisms involved and whether AM affects the production of endothelin, cytokines and other adipokines.

Project Title:	Adrenomedullin in the male sex acessory glands: gene expression, levels and receptor binding, functions and regulation of production in the prostate, seminal vesicle and coagulating gland.
Investigator(s):	Tang F, O WS
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	09/2008

Abstract:

(1) To establish the paracrine actions of adrenomedullin on the secretion and contraction of the male sex accessory glands; (2) To find out the effects of adenomedullin on endothelin-1 and endothelin-1 stimulated contraction; (3) To study the regulation of adrenomedullin production by testosterone and endothelin-1; (4) To study the interaction with the adrenergic system for contraction; (5) To confirm whether the male sex accessory glands are the source of the adrenomedullin in the seminal fluid; (6) To study the roles of adrenomedullin in the seminal plasma on the production of reactive oxygen species and cytokines in the uterus.

Project Title:	Adrenomedullin gene expression in rats before puberty.
Investigator(s):	Tang F
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	11/2008

Abstract:

Adrenomedullin (ADM) is a peptide hormone with a wide distribution (Hwang & Tang 1999; Hwang & Tang 2000). It has many physiological functuons including vasodilation, water and sodium excretion (Hannan & Buchmann 1996). ADM is also involved in organogenesis in the embryo (Garayoa et al. 2002). In the newborn, its level is found to be increased by birh stress (Boldt et al. 1998) and it may be important in perinatal adaptation (Rudolph (1998). ADM has been found in some tissues in the immature animals, particularly the heart (Autelitano et al. 2001) and the lung (Marionic et al.) However, there is no study on the age-related changes in the peptide level and gene expression of ADM before puberty, and the receptor component proteins at this stage have not been studied. The objectives of this study are: (1) To study the changes in ADM peptide and gene expresion in rats of different ages, 1 day, 3 days, 1 week, 2 weeks, 3 weeks (weaning) and compare with adult levels; and (2) to look at the gene expression of receptor component proteins at these time intervals. Autelitano DJ, Ridings R, Tang F. (2001) Cardiovasc Re 51: 255-264. Bodt T, Luukaimen P, Fyhrquist F et al. (1998) Acta Paediatr 87: 93-94. Gararayoa M, Bodegas F, Cuttitta F et al. (2002) Microsc Res Tech 57: 40-54. Hannan FWF, Buchanan KD (1996) Q. J. Med. 89: 881-884. Hwang ISS Tang F (1999) Neurosci. Lett. 267: 85-88. Hwang ISS, Tang F (2000) Neuropeptides 34: 42-47. Marioni E, Di Iorio R, Alo P et al. (1999) Pediatr Res 45: 282-285. Rudolf AM (1998) Acta Paediatr 87: 235-236.

Project Title:	Interaction of adrenomedullin and adipocytokines and adipokines in the soleus muscle and epididymal fat pad.
Investigator(s):	Tang F, O WS
Department:	Physiology
Source(s) of Funding:	Small Project Funding
Start Date:	09/2009

Abstract:

Objectives : (1) To study the effect of adrenomedullin on tissue necrosis factor-alpha (TNFα), interleukin 6 (IL-6), leptin and adiponectin in the soleus muscle and the epididymal fat pad of the rat. (2) To study the effect of TNFα, leptin and adiponectin on adrenomedullin in the soleus muscle and epididymal fat pad. (3) To study the effect of hydrogen peroxide on adenomedullin in the soleus muscle and the epididymal fat pad. Background: In our laboratory we have found that adrenomedullin increases the blood glucose level in the hyperinsulinemic euglycemic clamp study of the rat and that adrenomedullin decreases insulin-stimulated glucose uptake in the solues muscle and epididymal fat pad and increases lipolysis, suggesting that adrenomedullin may increase insulin resistance. TNFα and IL-6 are known to increase insulin resistance (Faraj Lu & Cianflone 2004) while leptin and adiponectin have been shown to decrease insulin resistance (Faraj Lu & Cianflone 2004), partly via a decrease of an increase in glucose uptake. Thus TNFα and IL-6 have a similar effect as adrenmedullin while leptin and adiponectin have opposite effects. ADM may increase insulin resistance through a change in the production of these cytokines ((Wong et al. 2004). On the other hand, TNFα may increase ADM production in adipocytes (Li et al. 2003). Our hypothesis is that these adipokines may interact to bring about a summated insulin resistance dependent on the physiological condition. The increase in insulin resistance leads to hyperglycaemia, and hyperglycaemia may result in an increase in oxidative stress (Wu et al. 2005). Oxidative stress is known to aggravate insulin resistance (Dokken et al. 2008; Vichaiwong et al. 2009). On the other hand, oxidative stress has been shown to increase adrenomedullin production in a number of tissues (Chun et al. 2000; Yoshihara et al. 2002). It is interesting to find out whether increase in oxidative stress in the soleus muscle and the epididymal fat pad will lead to an increase in adrenomedullin production, thus leading to further increase in insulin resistance. Chun TH, Itoh H, Saito T, Yamahara K et al. (2000) J Hypertens 18, 575-580 Dokken BB, Saengsirisuwan V, Kim JS, Teachey MK et al. (2008) Am J Physiol. 294, E615-621.. Faraj Lu HK & Cianflone K (2004) Biochem Cell Biol 82, 170-190. Li Y, Totsune K, Takeda K, Furuyama K et al. (2003) Eur J Endcorinol 149, 231-238. Vichaiwong K, Henriksen EJ, Toskulkao C, Prasannarong M et al. (2009) Free Radic Biol Med [Epub ahed of print]. Wong LY, Cheung BM, Li YY & Tang F (2005) Endocrinology 112, 1796-1808. Wu X, Zhu L, Zilbering A, Mahadev K et al. (2005) Antioxid Redox Signal 7, 526-537. Yoshihara F, Horio T, Nishikimi T, Matsuo H et al. (2002) Eur J Pharmacol 436, 1-6.

List of Research Outputs

Chiu C.N., Liao S., Lam K.W., Tang F., Ho J.C.M., Ho P.C., O W.S., Yao Q.Y. and Yeung W.S.B., Adrenomedullin regulates sperm motility and oviductal ciliary beat via cyclic adenosine 5'-monophosphate/protein kinase A and nitric oxide, Endocrinology. 2010, 151(7): 3336-3347.

Chiu C.N., Lam K.W., Lee C.L., Chung M.K., Huang W., O W.S., Tang F., Ho P.C. and Yeung W.S.B., The role of adrenomedullin in regulating human sperm motility , In: European Society of Human Reproduction and Embryology, 26th Annual Meeting of the European-Society-of-Human-Reproduction-and-Embryology Rome, Italy, Jun 27-30, 2010. ESHRE, P-059.

Li L., Tang F. and O W.S., Adrenomedullin in rat corpus luteum and its role in steroidogenesis during pregnancy, Biology of Reproduction. 2009, 81: 542.

Li L., Hwang I.S.S., Tang F., O W.S. and Li Y.Y., Coexpression of adrenomedullin and its receptors in the reproductive system of the rat: effects on sterold secretion in rat ovary, Yakhteh Medical Journal. 2009, 11(1): 36.

Li R.H.W., Liao S., Chiu C.N., Tam W.W., Ho J.C.M., Ng E.H.Y., Ho P.C., Yeung W.S.B., Tang F. and O W.S., Expression of adrenomedullin in human oviduct, its regulaton by the hormonal cycle and contact with spermatozoa, and its effect on ciliary beat frequency of the oviductal epithelium, Journal of Clinical Endocrinology and Metabolism. 2010, 95(9): E18-E25.

O W.S., Liao S., Sun J.Z., Ho J.C.M., Chiu C.N., Ng E.H.Y., Yeung W.S.B., Li R.H.W. and Tang F., Adrenomedullin and oviduct function in human and rats, Biology of Reproduction. 2009, 81: 99.

O W.S., Li L., Cheung M.P.L. and Tang F., The role of adrenomedullin in embryo implantation in the rat, The First State Key Laboratory of Reproductive Biology on Frontiers in Perrimplantation Biology. 2010, 60.

Researcher : Tang WH

List of Research Outputs

Tang W.H., Cheng W.T., Kravtsov G.M., Tong X.Y., Hou X.Y., Chung S.K. and Chung S.S.M., Cardiac contractile dysfunction during acute hyperglycemia due to impairment of SERCA by polyol pathway-mediated oxidative stress, American Journal of Physiology and Cell Physiology. 2010, 299: C643-C653.

Tang W.H., Kravtsov G.M., Sauert M., Tong X.Y., Hou X.Y., Wong T.M., Chung S.K. and Chung S.S.M., Polyol pathway impairs the function of SERCA and RyR in ischemic-reperfused rat hearts by increasing oxidative modificaitons of these proteins, Journal of Molecular and Cellular Cardiology. 2010, 49: 58-69.

Researcher : Tong HY

List of Research Outputs

Tong H.Y., Guo J.J., Xu S.X., Mak M.C., Chung S.K., Chung S.S.M., Huang A.L. and Ko B.C.B., Inducible nucleosome depletion at OREBP-binding-sites by hypertonic stress, PLoS ONE. 2009, 4(12): e8435.

Researcher : Tse YC

List of Research Outputs

Lai S.K., Tse Y.C., Hu H., Wong T.P., Yung W.H. and Chan Y.S., Maturation profile of inhibitory and excitatory postsynaptic currents in central vestibular neurons of rats, Society Neuroscience Abstract (USA). 2009, 813.14/B62.

Ma C.W., Lai C.H., Lai S.K., Tse Y.C., Yung K.K., Shum D.K.Y. and Chan Y.S., Developmental distribution of vestibular nuclear neurons responsive to different speeds of horizontal translation, Brain Research. 2010, 1326: 62-67.

Researcher : Wei W

List of Research Outputs

Yue J., Wei W., Lam M.C., Zhao Y., Zhang L.R., Zhang L.H. and Lee H.C., The CD38/cADPR/Ca2+-pathway promotes cell proliferation and delays NGF-induced differentiation in PC12 cells. , Journal of Biological Chemistry . 2009, 284: 29335-29342.

Researcher : Wong TM

Project Title:	First Asia-Pacific Opioid Symposium Cardioprotective Effects of K-Opioids
Investigator(s):	Wong TM
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	08/2000

Abstract:

N/A

Project Title:	XVIII World Congress International Society for Heart Research in Conjunction with 52nd Annual Scientific Meeting of the Cardiac Society of Australia & New Zealand Delayed Cardioprotection of Kappa Opioid Receptor Stimulation in Normal and Diabetic Rats - Roles of Heat Shock Protein 70 and Intracellular Ca2+
Investigator(s):	Wong TM
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	08/2004

Abstract:

N/A

Project Title:	CSANZ 2006 Annual Scientific Meeting Heat Shock Protein 70, Calcium Regulation and Cardiac Survival
Investigator(s):	Wong TM
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	08/2006

Abstract:

N/A

List of Research Outputs

Fan M.H.M., Wong K.L., Wu S., Leung W.K., Yam W.C. and Wong T.M., Preconditioning with Porphyromonas gingivalis lipopolysaccharide may confer cardioprotection and improve recovery of the electrically induced intracellular calcium transient during ischemia and reperfusion, Journal of Periodontal Research. 2010, 45: 100-108.

Tang W.H., Kravtsov G.M., Sauert M., Tong X.Y., Hou X.Y., Wong T.M., Chung S.K. and Chung S.S.M., Polyol pathway impairs the function of SERCA and RyR in ischemic-reperfused rat hearts by increasing oxidative modificaitons of these proteins, Journal of Molecular and Cellular Cardiology. 2010, 49: 58-69.

Zhang Y., Irwin M.G., Li R., Chen Z.W. and Wong T.M., Effects of remifentanil on intracellular Ca2+ and its ransients induced by electrical stimulation and caffine inrat ventricuar myocytes, Chinese Medical Journal. 2009, 122(12): 1439-1443.

Zhou Y., Wong T.M. and Li G.R., Ionic mechanisms of chloroform induced arrhythmia, FEBS Journal. 2009, 276(Suppl. 1): 354-5.

Researcher : Yeung HM

List of Research Outputs

Yeung H.M., Hung M.W., Kravtsov G.M. and Fung M.L., Chronic intermittent hypoxia exacerbates oxidative stress and deteriorates calcium homeostasis in rat hearts. 63^rd High Blood Pressure Research Conference, American Heart Association, USA 9/2009.

Researcher : Yiu NSC

List of Research Outputs

Lai C.H., Yiu N.S.C., Lai S.K., Ng K.P., Yung K.K., Shum D.K.Y. and Chan Y.S., Maturation of canal-related brainstem neurons in the detection of horizontal angular acceleration in rats, Journal of Comparative Neurology. 2010, 518: 1742-1763.

Researcher : Yue J

Project Title:	Dissecting the mechanism of cADPR-mediated calcium signaling in mammalian cells
Investigator(s):	Yue J, Lee HC
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	03/2008
Completion Date:	02/2010

Abstract:

Mobilization of intracellular Ca2+ stores is involved in many diverse cell functions, including fertilization, muscle contraction, secretion of neurotransmitters, hormones and enzymes, and lymphocyte activation and proliferation [1-3]. Cyclic adenosine diphosphoribose (cADPR) is an endogenous Ca2+ mobilizing nucleotide present in many cell types and different species, including protozoa, plants, and animals. cADPR is formed by ADP-ribosyl cyclases from nicotinamide adenine dinucleotide (NAD). The main ADP-ribosyl cyclase is CD38, a multi-functional enzyme and a type II membrane protein. It has been shown that many extracellular stimuli can induce cADPR production that leads to calcium release or influx, establishing cADPR as a second messenger [4-6]. However, the molecular mechanisms mediating the stimulus-induced cADPR production have not been resolved. In addition, although evidence indicates that the ryanodine receptor is the main intracellular target for cADPR, it is unclear whether cADPR elicits Ca2+ release by direct binding to the ryanodine receptor or via an accessory protein(s). Given the pivotal role of cADPR-mediated calcium signaling pathway in a wide variety of cellular processes, it is of great interest to further dissect the molecular mechanism of the cADPR signaling pathway. There are two specific aims in this proposal: (1) To define the signaling pathway mediating the stimulus-induced cADPR production in cells. (2) To identify protein components which are important for the calcium releasing activity of cADPR.

Project Title:	Identifying novel regulators in cADPR-mediated calcium signaling by combining approaches of synthetic organic chemistry and RNAi screen
Investigator(s):	Yue J
Department:	Physiology
Source(s) of Funding:	Travel Grants for NSFC/RGC JRS
Start Date:	12/2008

Abstract:

Travel grants for NSFC/RGC JRS

Project Title:	The Role and mechanism of cADPR and NAADP in the proliferation and differentiation of neural stem cells
Investigator(s):	Yue J, Wu W, Lee HC
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	03/2009

Abstract:

Cyclic adenosine diphosphoribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) are two endogenous Ca2+ mobilizing nucleotides present in many cell types and different species, from plants to animals. Both cADPR and NAADP have been linked to a wide variety of cellular processes. We have shown recently that the CD38/cADPR signaling is required for acetylcholine (Ach)-induced Ca2+ increase and cell proliferation in neurosecretory PC12 cells. It also has been reported by others that Ach potently stimulates the proliferation of neural stem cell through a chemical screening of molecules that affect neurotransmission pathways in neural stem cells (Diamandis et al., Nat Chem Biol. 2007 3:268-73). Moreover, we demonstrated that inhibition of the CD38/cADPR/ Ca2+ signaling enhances nerve growth factor (NGF)-induced neuronal differentiation in PC12 cells. In addition, NAADP is a potent neuronal differentiation inducer in PC12 cells. We, therefore, hypothesize that cADPR or NAADP plays a role in the proliferation and differentiation of neural stem cells. It is now well accepted that neurogenesis occurs not only in the normal adult brain and but also in patients with defective neurological diseases. Means to regulate the proliferation and differentiation of neural stem cells may reduce disease progression. On the other hand, neural stem cells have been implicated to be responsible for the proliferation of brain tumors, therefore the elucidation of mechanisms of neural stem cell self-renewal will also points to a potential therapeutic targets for treatment of brain tumors. There are two specific aims in this proposal: (1). To study the role and mechanism of the CD38/cADPR signaling in Ach-stimulated Ca2+ changes and proliferation in neural stem cells. (2). To examine the role and mechanism of NAADP and cADPR in the neural stem cell differentiation.

Project Title:	Mechanism of melamine-induced human urinary bladder carcinoma
Investigator(s):	Yue J, Lee HC
Department:	Physiology
Source(s) of Funding:	Studies Related to Melamine Incident
Start Date:	04/2009

Abstract:

To assess the ability of melamine or its associated calculi to induce the proliferation, transformation, tumorigenesis, and metastasis in human bladder epithelial cells; to dissect the mechanisms of melamine-induced human bladder carcinoma; to screen the therapies for melamine-induced carcinoma.

Project Title:	Dissecting the mechanism and function of the CD38/cADPR/Ca2+ signaling in PC12 cell proliferation and differentiation
Investigator(s):	Yue J, Chan YS, Lee HC
Department:	Physiology
Source(s) of Funding:	General Research Fund (GRF)
Start Date:	10/2009

Abstract:

1) To determine how the CD38/cADPR signaling is required for acetylcholine-induced PC12 cell proliferation; 2) To examine the function and mechanism of the CD38/cADPR signaling in NGF-induced neuronal differentiation in PC12 cells.

Project Title:	Identifying novel regulators in cADPR-mediated calcium signaling by combining approaches of synthetic organic chemistry and RNAi screen
Investigator(s):	Yue J, Lee HC
Department:	Physiology
Source(s) of Funding:	NSFC/RGC Joint Research Scheme
Start Date:	12/2009

Abstract:

To chemically synthesize and pharmacologically characterize novel and potent cell-permeant cADPR agonists; to identify novel regulators in cADPR-mediated calcium signaling using RNAi screen.

Project Title:	49th Annual Meeting of the American Society for Cell Biology Modulation of the neural lineage entry of mouse embryonic stem cells by the CD38/cADPR/Ca2+ signaling pathway
Investigator(s):	Yue J
Department:	Physiology
Source(s) of Funding:	URC/CRCG - Conference Grants for Teaching Staff
Start Date:	12/2009
Completion Date:	12/2009

Abstract:

N/A

List of Research Outputs

Yue J., 1. Modulation of the neural lineage entry of mouse embryonic stem cells by the CD38/cADPR/Ca2+ signaling pathway., 49th The American Society for Cell Biology Annual Meeting, San Diego, CA . 2009.

Yue J., Wei W., Lam M.C., Zhao Y., Zhang L.R., Zhang L.H. and Lee H.C., The CD38/cADPR/Ca2+-pathway promotes cell proliferation and delays NGF-induced differentiation in PC12 cells. , Journal of Biological Chemistry . 2009, 284: 29335-29342.

Researcher : Zhang H

Project Title:	Interaction studies of CD38 with CD4 and agnostic antibodies against CD38
Investigator(s):	Zhang H, Hao Q
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	03/2009
Completion Date:	03/2010

Abstract:

Human immunodeficiency virus 1 (HIV-1) infects lymphocytes via its envelope glycoprotein gp120, which is non-covalently associated with transmembrane protein gp41 on the virus surface. Gp120 binds with high affinity to lymphocyte CD4 molecule that serves as the main virus receptor. This binding triggers conformational changes in the gp120-gp41 complex and promotes viral fusion with the cell membrane and entry into the cell. However, CD4 expression is not in itself sufficient to allow viral entry. By contrast, CD4-bound HIV-1 particles need to interact with other cell surface molecules serving as HIV co-receptors. The finding that treatment with gp120 significantly increases CD4 association with CD38 on lymphocytes suggests that CD38 might be also playing vital roles in the entry of HIV-1. Further study shows that the expression of CD38 inhibits lymphocytes susceptibility to HIV infection through inhibiting gp120/CD4-dependent viral binding to target cells. The most recent investigation reveals that CD38 interferes with HIV-1 fusion through a sequence homologous to the V3 loop of gp120. However, the crystal structure of gp120 with CD4 shows that gp120 doesn't bind to CD4 through its V3 loop. And, gp120 and CD4 are on opposing membranes; while CD38 is on the same membrane as CD4. Here come the questions: how does CD38 bind to CD4 and how does this binding interfere with the binding between gp120 and CD4? To answer these questions, we propose to study the binding properties between CD4 and CD38. Because CD38 is also a therapeutic target of B cell chronic lymphocyte leukemia, antibodies against CD38 is used directly in the therapy of B-CLL or as a tool to deliver toxins to target cells. We also propose to study the interactions between CD38 and anti-CD38 antibodies. Structural comparison between the binding interfaces of CD38 with its agonistic and non-agonistic antibodies will reveal how CD38 is activated and provide structural basis for antibody maturation and therapeutics design. The result of this project will provide the interaction details and will form the foundation for pharmaceutical applications. Specific objectives of the project are: 1) To determine the binding affinity between CD4 and CD38 and map the binding domain(s) of CD4 2) To determine the structure of CD38 in complex with the binding domain(s) of CD4 3) To determine the structures of CD38 with the Fab fragments of anti-CD38 antibodies

Project Title:	Structural studies of influenza proteins NEP and M1: implications for rational drug design
Investigator(s):	Zhang H, Hao Q
Department:	Physiology
Source(s) of Funding:	Seed Funding Programme for Basic Research
Start Date:	03/2010

Abstract:

Influenza viruses cause annual epidemics and occasional pandemics that have claimed the lives of millions. The emergence of new strains will continue to pose challenges to public health and the scientific communities. A prime example is the recent emergence of swine-origin H1N1 viruses that have transmitted to and spread among humans, resulting in outbreaks world wide. Up to the end of October, swine flu has claimed more 5,700 human lives according to WHO’s report. Influenza A viruses contain a genome composed of eight segments of single-stranded, negative RNA encoding totally 11 proteins, including two surface proteins haemagglutinin (HA) and neuraminidase (NA). The RNA genome is transcribed by its own polymerase PA, PB1 and PB2. RNA transcription is associated with many point mutations persistently producing many changes in virus proteins including the surface proteins HA and NA [1, 2]. The mutations in surface proteins result in antigen drift which helps the virus to escape the immunity of its host. Since the influenza virus genome is segmented into eight parts, two or more different virus variants infecting the same cell can produce progeny virus with a mixed genome, which may result in an antigenic shift, producing new virus strain. The currently circulating Swine-origin influenza A (H1N1) virus is a triple-reassortment of swine influenza A (H1N1) virus, avian influenza virus and human seasonal H3N2 viruses [3, 4]. Currently, there are two approved classes of antiviral drugs used against influenza, including NA inhibitors such as oseltamivir (Tamiflu) and zanamivir (Relenza), and M2 protein inhibitors (adamantane derivatives such as amantadine and rimantadine) [5]. Resistance to adamantanes arises quickly and frequently, and most circulating human H1N1 and H3N2 viruses, some H5N1 viruses, and most European porcine H1N1, H1N2 and H3N2 viruses, are resistant to adamantanes. The swine-origin influenza viruses (S-OIV) are also resistant to ion channel inhibitors [3]. NA inhibitors are currently being preferred for influenza virus infections since they are less toxic and more effective [5, 6]. Oseltamivir is generally regarded as the NA inhibitor of choice due to its more convenient administration route (oral) compared to zanamivir (inhalation). Initially, NA inhibitors were assumed to be less prone to select resistant influenza viruses than M2 protein inhibitors. However, treatment of H3N2 influenza led to resistance in 0.4% of adult cases and 5.5% of children [5]. Moreover, the CDC of USA released data showing a high level of oseltamivir resistance among nearly all seasonal influenza A/H1N1 isolates on 12 December 2008 [7]. Due to the high mutation rate and emerging resistance against neuraminidase inhibitors [8] and amantadine/rimantadine [9], it is of utmost importance to investigate inner conserved viral proteins as potential drug targets. The segment eight RNA fragment of influenza A virus encodes the non-structural (NS) proteins, namely NS1 and NS2 (now renamed NEP). Through binding to another viral protein M1, NEP functions as an adaptor between human exportin CRM1 and vRNP during exporting of newly synthesized vRNP from the nucleus to the cytoplasm [10, 11]. Through sequence analysis of 1195 NEP proteins, novel highly conserved sites have been identified for NEP protein, and several conserved drug binding sites have been predicted [12]. In this application, we will focus on the structural studies of NEP and M1 and reveal the binding interface between NEP and M1. This kind of study will definitely provide detailed information for potential universal drug design.

List of Research Outputs

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Croucher ASI 2009 "Structure-based screening and design of ligands for protein targets". 2009.

Kotaka M., Zhang H., Graeff R., Lee H.C. and Hao Q., Structural studies of intermediates along the reaction pathway of ADP-ribosyl cyclase , Joint Meeting of the HK Society of Neurosciences and the Biophysical Society of Hong Kong. 2010.

Zhang H., Astrof N.S., Liu J.H., Wang J.H. and Shimaoka M., Crystal structure of isoflurane bound to integrin LFA-1 supports a unified mechanism of volatile anesthetic action in the immune and central nervous systems, FASEB J. 2009, 23(8): 2735-40.

Zhang H., Liu J.H., Yang W., Springer T., Shimaoka M. and Wang J.H., Structural basis of activation-dependent binding of ligand-mimetic antibody AL-57 to integrin LFA-1, Proc Natl Acad Sci U S A. 2009, 106(43): 18345-50.

Researcher : Zhao Y

List of Research Outputs

Yue J., Wei W., Lam M.C., Zhao Y., Zhang L.R., Zhang L.H. and Lee H.C., The CD38/cADPR/Ca2+-pathway promotes cell proliferation and delays NGF-induced differentiation in PC12 cells. , Journal of Biological Chemistry . 2009, 284: 29335-29342.

Researcher : Zhou Y

List of Research Outputs

Li G.R., Sun H., Chen J., Zhou Y., Tse H.F. and Lau C.P., Characterization of Multiple Ion Channels in Cultured Human Cardiac Fibroblasts. , PLoS One. 2009, 4(10): e7307.

Zhou Y., Wong T.M. and Li G.R., Ionic mechanisms of chloroform induced arrhythmia, FEBS Journal. 2009, 276(Suppl. 1): 354-5.

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