Characterization of the chromatin accessibility profile of Plagl1+/-pat retina

Retinal damage triggers reactive gliosis in Müller glia across vertebrate species, but only in regenerative animals, such as teleost fish, do Müller glia initiate repair; proliferating and undergoing neurogenesis to replace lost cells. We found that Plagl1, a maternally imprinted gene, is dynamically regulated in reactive Müller glia post-insult, with transcript levels transiently increasing before stably declining. To study Plagl1 retinal function, we examined Plagl1+/-pat null mutants postnatally, revealing defects in retinal architecture, visual signal processing and a reactive gliotic phenotype. Plagl1+/-pat Müller glia proliferate ectopically and give rise to inner retinal neurons and photoreceptors. Transcriptomic and ATAC-seq profiles revealed similarities between Plagl1+/-pat retinas and neurodegenerative and injury models, including an upregulation of pro-gliogenic and pro-proliferative pathways, such as Notch, not observed in wild-type retinas Plagl1 is thus an essential component of the transcriptional regulatory networks that retain mammalian Müller glia in quiescence.