Active DNA demethylation is upstream of rod photoreceptor fate determination and required for retinal development [snRNA-seq]

The goal of this study is to investigate the role of TET enzyme-mediated DNA demethylation on retinal development and cell fate specification. We utilized an allelic series of TET enzyme retinal conditional mouse mutants using the Chx10-Cre-GFP transgene, removing the TET enzymes from retinal progenitor cells. We observe that inhibition of DNA demethylation results in abnormal retinal development and a loss of visual function. Immunohistological and genomic profiling (RNA-seq, scRNA-seq, WGBS, and bACE-seq) indicate that rod photoreceptor gene regulatory networks are inhibited when DNA demethylation is lost, indicating that DNA demethylation is required for NRL and NR2E3 expression, resulting in a retina with increased specification of cone photoreceptors. PIPseq single nucleus RNA-sequencing to profile gene expression patterns within individual retinal cells in post-natal day 21 (P21) mouse retinas from Cre-negative control and Tet1/Tet2/Tet3 conditional mutant animals. Recombination of floxed TET exons was induced in retinal progenitor cells using the Chx10-Cre-GFP transgene. Experiments were performed on pooled samples (> 4 retinas each) from 2 separate nuclear dissociations for each genotype