title: Comparative genomics identification of a novel set of temporally regulated hedgehog target genes in the retina.
abstract: The hedgehog (Hh) signaling pathway is involved in numerous developmental and adult processes with many links to cancer. In vertebrates, the activity of the Hh pathway is mediated primarily through three Gli transcription factors (Gli1, 2 and 3) that can serve as transcriptional activators or repressors. The identification of Gli target genes is essential for the understanding of the Hh-mediated processes. We used a comparative genomics approach using the mouse and human genomes to identify 390 genes that contained conserved Gli binding sites. RT-qPCR validation of 46 target genes in E14.5 and P0.5 retinal explants revealed that Hh pathway activation resulted in the modulation of 30 of these targets, 25 of which demonstrated a temporal regulation. Further validation revealed that the expression of Bok, FoxA1, Sox8 and Wnt7a was dependent upon Sonic Hh (Shh) signaling in the retina and their regulation is under positive and negative controls by Gli2 and Gli3, respectively. We also show using chromatin immunoprecipitation that Gli2 binds to the Sox8 promoter, suggesting that Sox8 is an Hh-dependent direct target of Gli2. Finally, we demonstrate that the Hh pathway also modulates the expression of Sox9 and Sox10, which together with Sox8 make up the SoxE group. Previously, it has been shown that Hh and SoxE group genes promote Müller glial cell development in the retina. Our data are consistent with the possibility for a role of SoxE group genes downstream of Hh signaling on Müller cell development.
authors.affiliation: Vision Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6.
authors.forename: Brian
authors.initials: B
authors.lastname: McNeill
authors.forename: Carol
authors.initials: C
authors.lastname: Perez-Iratxeta
authors.forename: Chantal
authors.initials: C
authors.lastname: Mazerolle
authors.forename: Marosh
authors.initials: M
authors.lastname: Furimsky
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mishina
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Andrade-Navarro
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Wallace
mesh_terms: D000818:Animals; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D012160:Retina / Q000378:metabolism*; D055757:SOXE Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000071676:Zinc Finger Protein GLI1
chemical_list: C400551:GLI1 protein, human; C498520:Gli1 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D055757:SOXE Transcription Factors; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1