title: Disruption of Krox-20 results in alteration of rhombomeres 3 and 5 in the developing hindbrain.
abstract: The zinc finger gene Krox-20 is transcribed in two alternate segments (rhombomeres) of the developing hindbrain. To investigate its function, we have used homologous recombination to generate mice carrying an in-frame insertion of the E. coli lacZ gene within Krox-20. Analysis of the beta-galactosidase pattern in heterozygous embryos confirmed the known profile with expression restricted to rhombomeres (r) 3 and 5. Mice homozygous for the mutation die during the first two weeks after birth. Anatomical analysis of the hindbrain and of the cranial nerves during embryogenesis, combined with the determination of the expression patterns of rhombomere-specific genes, demonstrated that Krox-20 inactivation results in a marked reduction or elimination of r3 and r5. We conclude that Krox-20, although not required for the initial delimitation of r3 and r5, plays an important role in the process of segmentation governing hindbrain development.
authors.affiliation: Unité 368 de l'Institut National de la Santé et de la Recherche Médicale, Biologie Moléculaire du Développement, Ecole Normale Supérieure, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Schneider-Maunoury
authors.forename: P
authors.initials: P
authors.lastname: Topilko
authors.forename: T
authors.initials: T
authors.lastname: Seitandou
authors.forename: G
authors.initials: G
authors.lastname: Levi
authors.forename: M
authors.initials: M
authors.lastname: Cohen-Tannoudji
authors.forename: S
authors.initials: S
authors.lastname: Pournin
authors.forename: C
authors.initials: C
authors.lastname: Babinet
authors.forename: P
authors.initials: P
authors.lastname: Charnay
mesh_terms: D000375:Aging; D000818:Animals; D001933:Brain Stem / Q000196:embryology / Q000254:growth & development; D003391:Cranial Nerves / Q000196:embryology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D051767:Early Growth Response Protein 2; D004622:Embryo, Mammalian / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics; D005724:Ganglia / Q000196:embryology; D017353:Gene Deletion; D015870:Gene Expression; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D006579:Heterozygote; D006720:Homozygote; D051379:Mice; D008822:Mice, Transgenic; D016254:Mutagenesis, Insertional; D018168:Receptors, Retinoic Acid / Q000235:genetics; D011995:Recombination, Genetic; D012249:Rhombencephalon / Q000196:embryology* / Q000254:growth & development / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D016335:Zinc Fingers / Q000235:genetics*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; C497327:Egr2 protein, mouse; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; D001616:beta-Galactosidase