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The principal research area of the Retinal Neurobiology Laboratory, under the direction of
You-Wei Peng, MD.Ph.D., is the neurobiology of vertebrate photoreceptors and the molecular mechanisms underlying retinal degeneration. One of our current projects is to study the disease mechanism of retinal degeneration in Usher syndrome. We also study the mechanism of protein translocation in photoreceptors and synaptic remodeling during photoreceptor degeneration. Our most recent results indicate that several animal models of Usher syndrome show defective protein translocation in their photoreceptors. Even moderate light can induce degeneration of their photoreceptors. In collaboration with the Gene Expression Lab, Oxford Biomedica and the Foundation Fighting Blindness (FFB), we initiated a gene therapy study. Results of this study show that subretinal delivery of EIAV-based lentiviral vectors expressing wild type MYO7A in the shaker1, a well accepted model for Usher syndrome type 1B, is able to rescue the transducin translocation phenotype and protect the retina from light-induced photoreceptor degeneration in the shaker1 mice, demonstrating that these phenotypes are caused by dysfunction of myosin VIIa. We are currently studying the mechanism of how mutations in MYO7A cause defective translocation and light-induced photoreceptor degeneration in the shaker1 mice.
Usher Syndrome is the leading genetic disorder of combined blindness and deafness. The main clinical symptoms of the disease are retinitis pigmentosa (RP) and hearing loss. Affected individuals have a sensorineural hearing impairment at birth and later develop progressive RP (a special type of photoreceptor degeneration). Vestibular dysfunction and mental disturbances are also, in some cases, features of the syndrome. Several genes responsible for different forms of Usher syndrome have now been identified. The course and mechanism of retinal degeneration, however, remain unclear. Considering the tremendous burden imposed by the loss of both major senses and the fact that Usher syndrome is the major cause of deafness/blindness, it is important to pursue research into the causes of Usher syndrome in the hope that someday an effective therapy may be possible. Our most recent results indicate that even moderate light exposure can induce photoreceptor degeneration in several animal models of Usher syndrome. More importantly, when these animal models were reared under a moderate light (room light intensity)/dark cycle they develop severe retinal degeneration in less than 6 months. These finding demonstrate that Usher syndrome patients are thus likely vulnerable to light induced photoreceptor damage even under moderate room light.
Mei Tian, MD., Ph.D. (Post-Doc) Dr. Tian is an expert in protein biochemistry and molecular biology. She is studying the mechanism of protein translocation in photoreceptor.
Weimin Wang, MD. (Post-Doc) Dr. Wang is an expert in immunocytochemistry. His primary focus is on the mechanism of retinal pathogenesis associated with Usher syndrome.