title: Requirement for Map2k1 (Mek1) in extra-embryonic ectoderm during placentogenesis.
abstract: Map2k1(-/-) embryos die at mid-gestation from abnormal development and hypovascularization of the placenta. We now show that this phenotype is associated with a decreased labyrinth cell proliferation and an augmented cell apoptosis. Although the activation of MAP2K1 and MAP2K2 is widespread in the labyrinthine region, MAPK1 and MAPK3 activation is restricted to the cells lining the maternal sinuses, suggesting an important role for the ERK/MAPK cascade in these cells. In Map2k1(-/-) placenta, ERK/MAPK cascade activation is perturbed. Abnormal localization of the syncytiotrophoblasts is also observed in Map2k1(-/-) placenta, even though this cell lineage is specified at the correct time during placentogenesis. The placental phenotype can be rescued in tetraploid experiments. In addition, Map2k1-specific deletion in the embryo leads to normal embryo development and to the birth of viable Map2k1(-/-) mice. Altogether, these data enlighten the essential role of Map2k1 in extra-embryonic ectoderm during placentogenesis. In the embryo, the Map2k1 gene function appears dispensable.
authors.affiliation: Centre de recherche en cancérologie de l'Université Laval, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, QC G1R 2J6, Canada.
authors.forename: Vickram
authors.initials: V
authors.lastname: Bissonauth
authors.forename: Sophie
authors.initials: S
authors.lastname: Roy
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gravel
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Guillemette
authors.forename: Jean
authors.initials: J
authors.lastname: Charron
mesh_terms: D000483:Alleles; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002460:Cell Line; D002678:Chimera; D004622:Embryo, Mammalian / Q000166:cytology / Q000201:enzymology; D005260:Female; D005838:Genotype; D017403:In Situ Hybridization; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D010920:Placenta / Q000201:enzymology*; D015398:Signal Transduction
chemical_list: D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse