title: CHX10 targets a subset of photoreceptor genes.
abstract: The homeobox gene CHX10 is required for retinal progenitor cell proliferation early in retinogenesis and subsequently for bipolar neuron differentiation. To clarify the molecular mechanisms employed by CHX10 we sought to identify its target genes. In a yeast one-hybrid assay Chx10 interacted with the Ret1 site of the photoreceptor-specific gene Rhodopsin. Gel shift assays using in vitro translated protein confirmed that CHX10 binds to Ret1, but not to the similar Rhodopsin sites Ret4 and BAT-1. Using retinal nuclear lysates, we observed interactions between Chx10 and additional photoreceptor-specific elements including the PCE-1 (Rod arrestin/S-antigen) and the Cone opsin locus control region (Red/green cone opsin). However, chromatin immunoprecipitation assays revealed that in vivo, Chx10 bound sites upstream of the Rod arrestin and Interphotoreceptor retinoid-binding protein genes but not Rhodopsin or Cone opsin. Thus, in a chromatin context, Chx10 associates with a specific subset of elements that it binds with comparable apparent affinity in vitro. Our data suggest that CHX10 may target these motifs to inhibit rod photoreceptor gene expression in bipolar cells.
authors.affiliation: Toronto Western Research Institute, University Health Network, Ontario, Canada.
authors.forename: Kimberley M
authors.initials: KM
authors.lastname: Dorval
authors.forename: Brian P
authors.initials: BP
authors.lastname: Bobechko
authors.forename: Hiroki
authors.initials: H
authors.lastname: Fujieda
authors.forename: Shiming
authors.initials: S
authors.lastname: Chen
authors.forename: Don J
authors.initials: DJ
authors.lastname: Zack
authors.forename: Rod
authors.initials: R
authors.lastname: Bremner
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002417:Cattle; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D002843:Chromatin / Q000737:chemistry; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D005786:Gene Expression Regulation; D020868:Gene Silencing; D018398:Homeodomain Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D051381:Rats; D012160:Retina / Q000378:metabolism*; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D020798:Two-Hybrid System Techniques
chemical_list: D002843:Chromatin; D018076:DNA, Complementary; D018398:Homeodomain Proteins; D014157:Transcription Factors; C088975:Vsx2 protein, mouse; D004247:DNA; D012243:Rhodopsin