Identification of genes involved in photoreceptor recognition and synapse formation
Friday, September 14, 2018 — Poster Session V
- J Angueyra
- VP Kunze
- K Kindt
- W Li
Vision loss caused by photoreceptor death is a leading cause of irreversible blindness worldwide, but therapeutic options remain limited. Photoreceptors have recently been derived from stem cells, raising the promising possibility of cell-replacement therapies. A critical barrier to such therapy is the lack of successful integration of transplanted photoreceptors into existing retinal circuits, thwarting a reestablishment of function. Yet, little is known about the genes involved in recognition and synapse formation between photoreceptors and their postsynaptic partners. In the absence of this critical knowledge, the mechanistic framework necessary for developing such regenerative therapies will remain elusive. We propose a multifaceted approach to identify differentially expressed genes (DEGs) in cones that are involved in selective recognition and synapse formation. The zebrafish, a genetically accessible animal model, possesses a retina with four distinct cone subtypes (UV, S, M, and L-cones). Each subtype forms synapses with horizontal and bipolar cells in highly specific patterns. We hypothesize that DEGs in cones can be identified that are responsible for such specific patterns. We have acquired reporter lines for UV-, S-, M- and L-cones, allowing us to manually collect and isolate dissociated cones by subtype—we have already begun sequencing libraries generated from UV- and S-cones. Furthermore, we have generated mutant zebrafish lines using CRISPR/Cas9-guided mutations for other cone-enriched genes, providing a platform to test the consequences of knocking out identified DEGs. Finally, we have refined a screening method for evaluating cone synapse formation by combining transgenic horizontal/bipolar cell reporter lines with antibody staining against proteins both pre- and postsynaptic to photoreceptors. This combined approach will expose the genetic determinants of photoreceptor wiring, providing new therapeutic targets to promote the integration of transplanted photoreceptors in retinal degenerations.