title: Transcriptome of Atoh7 retinal progenitor cells identifies new Atoh7-dependent regulatory genes for retinal ganglion cell formation.
abstract: The bHLH transcription factor ATOH7 (Math5) is essential for establishing retinal ganglion cell (RGC) fate. However, Atoh7-expressing retinal progenitor cells (RPCs) can give rise to all retinal cell types, suggesting that other factors are involved in specifying RGCs. The basis by which a subpopulation of Atoh7-expressing RPCs commits to an RGC fate remains uncertain but is of critical importance to retinal development since RGCs are the earliest cell type to differentiate. To better understand the regulatory mechanisms leading to cell-fate specification, a binary genetic system was generated to specifically label Atoh7-expressing cells with green fluorescent protein (GFP). Fluorescence-activated cell sorting (FACS)-purified GFP(+) and GFP(-) cells were profiled by RNA-seq. Here, we identify 1497 transcripts that were differentially expressed between the two RPC populations. Pathway analysis revealed diminished growth factor signaling in Atoh7-expressing RPCs, indicating that these cells had exited the cell cycle. In contrast, axon guidance signals were enriched, suggesting that axons of Atoh7-expressing RPCs were already making synaptic connections. Notably, many genes enriched in Atoh7-expressing RPCs encoded transcriptional regulators, and several were direct targets of ATOH7, including, and unexpectedly, Ebf3 and Eya2. We present evidence for a Pax6-Atoh7-Eya2 pathway that acts downstream of Atoh7 but upstream of differentiation factor Pou4f2. EYA2 is a protein phosphatase involved in protein-protein interactions and posttranslational regulation. These properties, along with Eya2 as an early target gene of ATOH7, suggest that EYA2 functions in RGC specification. Our results expand current knowledge of the regulatory networks operating in Atoh7-expressing RPCs and offer new directions for exploring the earliest aspects of retinogenesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, 77030.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Gao
authors.forename: Chai-An
authors.initials: CA
authors.lastname: Mao
authors.forename: Ping
authors.initials: P
authors.lastname: Pan
authors.forename: Xiuqian
authors.initials: X
authors.lastname: Mu
authors.forename: William H
authors.initials: WH
authors.lastname: Klein
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D006657:Histones / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D058953:Neural Stem Cells / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D050765:Qa-SNARE Proteins / Q000378:metabolism; D051381:Rats; D012160:Retina / Q000166:cytology* / Q000196:embryology; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D050820:Transcription Factor Brn-3B / Q000172:deficiency / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D006657:Histones; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D017027:Protein Tyrosine Phosphatases; D050765:Qa-SNARE Proteins; D050820:Transcription Factor Brn-3B; D014157:Transcription Factors; C500943:Atoh1 protein, mouse; C110117:Ebf3 protein, mouse; C085559:Pou4f2 protein, mouse; C501159:Eya2 protein, mouse
keywords: Atoh7/Math5; eyes absent homolog2; gene regulatory network; retinal ganglion cells; retinal progenitor cells