Rbpj direct regulation of Atoh7 transcription in the embryonic mouse retina

Abstract

In vertebrate retinal progenitor cells, the proneural factor Atoh7 exhibits a dynamic tissue and cellular expression pattern. Although the resulting Atoh7 retinal lineage contains all seven major cell types, only retinal ganglion cells require Atoh7 for proper differentiation. Such specificity necessitates complex regulation of Atoh7 transcription during retina development. The Notch signaling pathway is an evolutionarily conserved suppressor of proneural bHLH factor expression. Previous in vivo mouse genetic studies established the cell autonomous suppression of Atoh7 transcription by Notch1, Rbpj and Hes1. Here we identify four CSL binding sites within the Atoh7 proximal regulatory region and demonstrate Rbpj protein interaction at these sequences by in vitro electromobility shift, calorimetry and luciferase assays and, in vivo via colocalization and chromatin immunoprecipitation. We found that Rbpj simultaneously represses Atoh7 transcription using both Notch-dependent and –independent pathways.

TheAtoh7remote enhancer provides transcriptional robustness during retinal ganglion cell development

“…Based on read density, CNE2 appears to be most accessible, with 854 peak reads per nucleotide, followed by CNE3, Pr (proximal), and Di. Interestingly, CNE2 contains the lead GWAS single-nucleotide polymorphism for optic disk size in humans, rs3858145 ( 26 , 31 , 33 ), and shows greater accessibility than the distal CNE, which contains binding sites for established regulators of Atoh7 transcription ( 21 – 23 , 69 , 70 ). In SE/SE mutants, open signatures for CNE2 and CNE3 were missing, as expected, but accessibility of the surrounding chromatin was unchanged.…”

“…Atoh7 transcription is regulated in part by conserved DNA elements (proximal and distal) located within 2.6 kilobases (kb) of the transcription start site (TSS). They harbor confirmed binding sites for PAX6, NEUROG2, and RBP-Jκ (CSL) transcription factors, but these features do not fully explain the dynamic pattern of Atoh7 expression (21)(22)(23)(24)(25).…”

Dynamic Polarization of Rab11a Modulates Crb2a Localization and Impacts Signaling to Regulate Retinal Neurogenesis

“…Studies using frog and chick retinas suggest a negative feedback loop where Notch pathway activation and Atoh7 provide instructive signals for proliferation or cell cycle exit (Agathocleous et al, 2009 ). Recent data further suggest that Notch signaling activates Hes gene expression and can lengthen the cell cycle to allow the accumulation of higher levels of Atoh7, essential to ganglion cell genesis and cell cycle exit (Chiodini et al, 2013 ; Miesfeld et al, 2018b , 2020 ). While it is clear that the activity of these transcription factors is instructive for cell fate decisions, less is known about the mechanisms that link cellular features and signaling to the heterogeneity of transcription factor expression and activity within individual RPCs prior to cell fate commitment.…”

Mapping developmental trajectories and subtype diversity of normal and glaucomatous human retinal ganglion cells by single-cell transcriptome analysis

“…Notch signaling is a gate‐way to differentiation; its inhibition is necessary for the progression of uncommitted progenitors along a specific lineage 29‐32 . Inhibition of Notch pathway leads to the activation of ATOH7 , a first essential step for committing the progenitors on the RGC lineage 33 . The mTOR pathway positively regulates RGC differentiation 11 and evidence suggests that this may involve interactions with the Notch pathway 34 .…”