title: Mice lacking connexin45 conditionally in cardiac myocytes display embryonic lethality similar to that of germline knockout mice without endocardial cushion defect.
abstract: The gap junction protein connexin45-deficient (Cx45-KO) mice die shortly after the hearts begin to beat. In addition to the heart defect, they also show defective vascular development which may be closely related with the cardiac phenotype. Therefore, we created mice whose floxed-Cx45 locus could be removed conditionally. We utilized cardiac alpha-actin-Cre transgenic mice to investigate the specific cardiac muscular function of Cx45 in vivo. The resultant conditional mutants were lethal, showing conduction block similar to that of the Cx45-KO mice. Unlike Cx45-KO, development of the endocardial cushion was not disrupted in the conditional mutants. X-gal staining was detected in the embryonic cardiac myocytes as a hallmark of Cre-loxP mediated floxed-Cx45 deletion. These results reconfirm the requirement of Cx45 for developing cardiac myocytes. These also indicate that establishing the first contractions is a crucial task for the early hearts.
authors.affiliation: Department of Developmental Molecular Anatomy, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors.forename: Kiyomasa
authors.initials: K
authors.lastname: Nishii
authors.forename: Madoka
authors.initials: M
authors.lastname: Kumai
authors.forename: Katsuko
authors.initials: K
authors.lastname: Egashira
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miwa
authors.forename: Kanako
authors.initials: K
authors.lastname: Hashizume
authors.forename: Yumi
authors.initials: Y
authors.lastname: Miyano
authors.forename: Yosaburo
authors.initials: Y
authors.lastname: Shibata
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D003001:Cloning, Molecular; D017630:Connexins / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology
chemical_list: D017630:Connexins; C082920:connexin 45