title: Conserved regulatory elements establish the dynamic expression of Rpx/HesxI in early vertebrate development.
abstract: TheRpx/Hesx1 homeobox gene is expressed during gastrulation in the anterior visceral and definitive endoderm and the cephalic neural plate. At later stages of development, its expression is restricted to Rathke's pouch, the primordium of the pituitary gland. This expression pattern suggests the presence of at least two distinct regulatory regions that control early and late Rpx transcription. Using transgenic mice, we have demonstrated that regulatory sequences in the 5' upstream region of Rpx are important for early expression in the anterior endoderm and neural plate and regulatory elements in the 3' region are required for late expression in Rathke's pouch. We have found that the genetically required LIM homeodomain-containing proteins Lim1/Lhx1 and Lhx3 are directly involved in the regulation of Rpx transcription. They bind two LIM protein-binding sites in the 5' upstream region of Rpx, which are required for Rpx promoter activity in both mice and Xenopus. Furthermore, we have found that a conserved enhancer in the 3' regulatory sequences of Rpx is not only required, but is also sufficient for the expression of Rpx transgenes in the developing Rathke's pouch.
authors.affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Shen-Ju
authors.initials: SJ
authors.lastname: Chou
authors.forename: Edit
authors.initials: E
authors.lastname: Hermesz
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Hatta
authors.forename: Doug
authors.initials: D
authors.lastname: Feltner
authors.forename: Heithem M
authors.initials: HM
authors.lastname: El-Hodiri
authors.forename: Milan
authors.initials: M
authors.lastname: Jamrich
authors.forename: Kathleen
authors.initials: K
authors.lastname: Mahon
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D004622:Embryo, Mammalian / Q000166:cytology; D004625:Embryo, Nonmammalian; D004707:Endoderm / Q000166:cytology; D005775:Gastrula; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D007031:Hypothalamus / Q000196:embryology / Q000378:metabolism; D007763:Lac Operon; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D019076:Transgenes; D014714:Vertebrates / Q000196:embryology*; D014981:Xenopus
chemical_list: D018398:Homeodomain Proteins; D008156:Luciferases