This proposal describes a 5 year training program for the development of an academic career in molecular retinal therapeutics. The principal investigator has recently completed an ophthalmology residency and vitreoretinal surgical fellowship. The proposed translational research program will identify changes in rod photoreceptor gene expression secondary to degeneration that are amenable to intervention and then develop vectors that target the most promising of these candidate genes. The program will require expertise in a wide range of molecular biology techniques including cutting-edge tools like RNA-seq. Dr. Constance Cepko, a recognized expert in the application of molecular biology, genetics, and virology to retinal research, will mentor the principal investigator in this new area of investigation. As Professor of Genetics and Ophthalmology at Harvard Medical School and Howard Hughes Medical Institute Investigator, Dr. Cepko has trained over 55 pre- and postdoctoral trainees, many of whom have gone on to academic faculty positions. An advisory committee f accomplished scientists in the fields of next-generation sequencing, mouse models of retinal degeneration, and viral vectors will provide additional scientific and career mentorship. Finally, the training program will take place in the very rich vision research and scientific communities of the Massachusetts Eye and Ear Infirmary and Harvard Medical School, offering many additional opportunities for education and collaboration. Research will focus on identifying molecular pathways in rod photoreceptors from rd1 retinas that may influence rod, and indirectly cone photoreceptor survival. Electroporation of histone deacetylase 4 (HDAC4) into an rd1 retina was recently found to protect rods from degeneration. Although cones were not electroporated, those in the vicinity of electroporated rods also survived. Understanding the protective mechanisms of HDAC4 may identify molecular pathways capable of slowing photoreceptor death across multiple mutations or even other diseases. The proposed experiments use RNA-seq to conduct transcriptome profiling of rods from three groups - wild type mice, rd1 mice, and rd1 mice electroporated with HDAC4. Gene expression altered by the disease process and reversed in rods from HDAC4-electroporated rd1 retinas will highlight candidate genes of interest. Immunocytochemistry, in situ hybridization, and quantitative PCR will independently confirm changes in gene expression found during transcriptome analysis. The most promising candidate genes will be cloned into plasmids for electroporation into rods. The constructs producing the best rescue phenotype will be incorporated into adeno-associated viral vectors (AAV) for stable pan-retinal gene transduction. Visual function of mice receiving AAV vectors can be assayed through behavioral assays and ERG. The proposed research and training program addresses important scientific questions while preparing the principal investigator for a career of independent investigation in this area of translational research.
We have recently found that the protein HDAC4 can save both rod and cone photoreceptors from death in retinas of rd1 mice, which harbor the same mutation found in some versions of the human disease, Retinitis Pigmentosa. The mechanism by which this protein acts is unknown, but may involve molecular pathways capable of slowing photoreceptor death across multiple mutations or even other diseases. We propose to perform molecular profiling of rod photoreceptors with RNA-seq to identify changes in candidate gene expression important in photoreceptor survival, modulating expression of the most promising genes in rd1 retina using electroporation and adeno-associated viral vectors, and then assaying for histological and behavioral evidence of rescue of photoreceptors from degeneration.