In vivo targeted mutagenesis of a regulatory element required for positioning the Hoxd-11 and Hoxd-10 expression boundaries.
Vertebrate Hox genes are required for the proper organization of structures along the rostrocaudal axis. Hoxd-11 is expressed in the posterior part of the embryo, up to the level of prevertebra 27, and its expression boundary is reproduced by a Hoxd-11/lacZ transgene. Expression of this transgene anterior to prevertebra 27 is prevented by the silencing activity of a cis-acting element, region IX. Using transgenic mice, we show that Hoxd-11 repression by region IX is necessary to position the sacrum properly. This silencing activity depends on phylogenetically conserved sequences able to bind in vitro retinoic acid receptors and COUP-TFs. ES cells were used to generate mice carrying a subtle mutation that abolishes binding of nuclear receptors to region IX. Mutant mice display an anterior shift of their lumbosacral transition inherited as a codominant trait. In mutant embryos, expression of both Hoxd-11 and Hoxd-10 mRNAs in the prevertebral column is anteriorized. These results illustrate the sharing, in cis, of a single regulatory element in order to establish the expression boundaries of two neighboring Hoxd genes.
Gérard
M
M
Department of Zoology and Animal Biology, University of Geneva, Sciences III, Switzerland.
Chen
J Y
JY
Gronemeyer
H
H
Chambon
P
P
Duboule
D
D
Zákány
J
J
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012447:Sacrum / Q000196:embryology / Q000473:pathology; D013234:Stem Cells; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes / Q000235:genetics; D029961:Zebrafish Proteins
D018398:Homeodomain Proteins; C490944:Hoxd10 protein, mouse; C490939:Hoxd11 protein, mouse; C489520:Hoxd4 protein, mouse; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D029961:Zebrafish Proteins; C099223:hoxd10a protein, zebrafish