title: Vertebrate caudal gene expression gradients investigated by use of chick cdx-A/lacZ and mouse cdx-1/lacZ reporters in transgenic mouse embryos: evidence for an intron enhancer.
abstract: The vertebrate caudal proteins, being upstream regulators of the Hox genes, play a role in establishment of the body plan. We describe analysis of two orthologous caudal genes (chick cdx-A and mouse cdx-1) by use of lacZ reporters expressed in transgenic mouse embryos. The expression patterns show many similarities to the expression of endogenous mouse cdx-1. At 8.7 days, cdx/lacZ activity within neurectoderm and mesoderm forms posterior-to-anterior gradients, and we discuss the possibility that similar gradients of cdx gene expression may function as morphogen gradients for the establishment of Hox gene expression boundaries. Our observations suggest that gradients form by decay of cdx/lacZ activity in cells that have moved anterior to the vicinity of the node. The cdx-A/lacZ expression pattern requires an intron enhancer that includes two functional control elements: a DR2-type retinoic acid response element and a Tcf/beta-catenin binding motif. These motifs are structurally conserved in mouse cdx-1.
authors.affiliation: Department of Development and Genetics, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK. stephen.gaunt@bbsrc.ac.uk
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Gaunt
authors.forename: Deborah
authors.initials: D
authors.lastname: Drage
authors.forename: Adam
authors.initials: A
authors.lastname: Cockley
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D007438:Introns; D007763:Lac Operon; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D019076:Transgenes; D014212:Tretinoin / Q000378:metabolism; D051176:beta Catenin
chemical_list: C495267:CTNNB1 protein, mouse; C491272:Cdx1 protein, mouse; D003598:Cytoskeletal Proteins; D018398:Homeodomain Proteins; D015534:Trans-Activators; D051176:beta Catenin; D014212:Tretinoin