Transcriptomic changes in retinal ganglion cell types associated with the disruption of cholinergic retinal waves
In the early stages of retinal development, a form of correlated activity known as retinal waves causes periodic depolarizations of immature retinal ganglion cells (RGCs). Retinal waves are crucial for refining visual maps in the brain's retinofugal targets and for the development of retinal circuits underlying feature detection, such as direction selectivity. Yet, how waves alter gene expression in immature RGCs is poorly understood, particularly at the level of the many distinct types of RGCs that underlie the retina's ability to encode diverse visual features. We performed single-cell RNA sequencing on RGCs isolated at the end of the first postnatal week from wild-type (WT) mice and ß2KO mice, which lack the ß2 subunit of the nicotinic acetylcholine receptor, leading to the disruption of cholinergic retinal waves. Statistical comparisons of RGC transcriptomes between the two conditions reveal a weak impact of retinal waves on RGC diversity, indicating that retinal waves do not influence the molecular programs that instruct RGC differentiation and maturation. Although wave-dependent gene expression changes are modest in the global sense, we identified ~238 genes that are significantly altered in select subsets of RGC types. We focused on one gene, Kcnk9, which encodes the two-pore domain leak channel potassium channel TASK3. Kcnk9, which is highly enriched in aRGCs, was strongly downregulated in ß2KO. We validated this result using in situ hybridization and performed whole-cell recording to demonstrate a significant decrease in the leak conductance in ß2KO. Our dataset provides a useful resource for identifying potential targets of spontaneous activity-dependent regulation of neurodevelopment in the retina. Overall design: RGCs from wild-type and ß2KO mice at postnatal day 7 (P7) were isolated using CD90-conjugated magnetic beads and analyzed using scRNA-seq.