title: Generation of a conditionally null allele of the laminin alpha1 gene.
abstract: Laminins are heterotrimeric glycoproteins of the basement membranes. Laminin 1 (alpha1, beta1, gamma1) is the major laminin expressed during early mouse embryogenesis. To gain access to the physiological function of laminin alpha1 chain, we developed a conditionally null allele of its encoding gene (Lama1) using the cre/loxP system. Floxed-allele-carrying mice (Lama1(flox/flox)) display no overt phenotype. Lama1(flox/flox) mice were crossed with transgenic deleter mice (CMV-Cre) to generate Lama1-deficient mice (Lama1(Delta/Delta)). Lama1(Delta/Delta) embryos die during the early postimplantation period after embryonic day 6.5. They lack Reichert's membrane, an extraembryonic basement membrane in which laminin alpha1 is normally highly expressed. In parallel, Lama1(Delta/Delta) embryos display 1) parietal and visceral endoderm differentiation defects with altered expression of cytokeratin 19 and GATA4, respectively, and 2) an induction of apoptosis. This new mouse model is of particular interest as it will allow time- and tissue-specific inactivation of the Lama1 gene in various organs.
authors.affiliation: Inserm, U682 Strasbourg, F67200, Development and Physiopathology of the Intestine and Pancreas, University Louis Pasteur, Strasbourg, France.
authors.forename: F
authors.initials: F
authors.lastname: Alpy
authors.forename: I
authors.initials: I
authors.lastname: Jivkov
authors.forename: L
authors.initials: L
authors.lastname: Sorokin
authors.forename: A
authors.initials: A
authors.lastname: Klein
authors.forename: C
authors.initials: C
authors.lastname: Arnold
authors.forename: Y
authors.initials: Y
authors.lastname: Huss
authors.forename: M
authors.initials: M
authors.lastname: Kedinger
authors.forename: P
authors.initials: P
authors.lastname: Simon-Assmann
authors.forename: O
authors.initials: O
authors.lastname: Lefebvre
mesh_terms: D000483:Alleles; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001485:Basement Membrane / Q000196:embryology; D002454:Cell Differentiation; D004622:Embryo, Mammalian / Q000166:cytology; D047108:Embryonic Development / Q000235:genetics; D004707:Endoderm / Q000166:cytology / Q000378:metabolism; D005091:Exons; D050991:GATA4 Transcription Factor / Q000378:metabolism; D017353:Gene Deletion; D005804:Genes, Lethal; D007633:Keratins / Q000378:metabolism; D007797:Laminin / Q000235:genetics* / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics
chemical_list: D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D007797:Laminin; C084098:laminin A; D007633:Keratins