title: ROCK1 expression is regulated by TGFbeta3 and ALK2 during valvuloseptal endocardial cushion formation.
abstract: During early heart development at the looped heart stage, endothelial cells in the outflow tract and atrioventricular (AV) regions transform into mesenchyme to generate endocardial cushion tissue. This endocardial epithelial-mesenchymal transition (EMT) is regulated by several regulatory pathways, including the transforming growth factor-beta (TGFbeta), bone morphogenetic protein (BMP), and Rho-ROCK pathways. Here, we investigated the spatiotemporal expression pattern of ROCK1 mRNA during EMT in chick and examined whether TGFbeta or BMP could induce the expression of ROCK1. At the onset of EMT, ROCK1 expression was up-regulated in endothelial/mesenchymal cells. A three-dimensional collagen gel assay was used to examine the mechanisms regulating the expression of ROCK1. In AV endocardium co-cultured with associated myocardium, ROCK1 expression was inhibited by either anti-TGFbeta3 antibody, anti-ALK2 antibody or noggin, but not SB431542 (ALK5 inhibitor). In cultured preactivated AV endocardium, TGFbeta3 protein induced the expression of ROCK1, but BMP did not. AV endothelial cells that were cultured in medium supplemented with TGFbeta3 plus anti-ALK2 antibody failed to express ROCK1. These results suggest that the expression of ROCK1 is up-regulated at the onset of EMT and that signaling mediated by TGFbeta3/ALK2 together with BMP is involved in the expression of ROCK1.
authors.affiliation: Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Osaka, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Sakabe
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Sakata
authors.forename: Hiroko
authors.initials: H
authors.lastname: Matsui
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ikeda
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamagishi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakajima
mesh_terms: D030201:Activin Receptors, Type I / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D019485:Bone Morphogenetic Proteins / Q000378:metabolism / Q000494:pharmacology; D002642:Chick Embryo; D017077:Culture Media, Conditioned; D017931:DNA Primers / Q000235:genetics; D054089:Endocardial Cushions / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D004848:Epithelium / Q000196:embryology; D005786:Gene Expression Regulation / Q000187:drug effects; D008648:Mesoderm / Q000196:embryology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D046509:Tissue Culture Techniques; D053782:Transforming Growth Factor beta3 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D015854:Up-Regulation; D054460:rho-Associated Kinases / Q000235:genetics*
chemical_list: D019485:Bone Morphogenetic Proteins; D017077:Culture Media, Conditioned; D017931:DNA Primers; D012333:RNA, Messenger; D053782:Transforming Growth Factor beta3; D054460:rho-Associated Kinases; D030201:Activin Receptors, Type I