title: Rho-associated kinases play an essential role in cardiac morphogenesis and cardiomyocyte proliferation.
abstract: Rho-associated coiled-coil kinases (ROCKs), initially identified as effectors for Rho GTPases, play a role in cardiac cell physiology and are also expressed in the developing heart. However, their role in cardiac development is not known. To investigate the role of these kinases in cardiac development, we examined cardiac development in cultured murine embryos treated with the ROCK inhibitor Y27632. After inhibition of ROCK activity, we found disturbed cardiac chamber formation and trabeculation. To further examine the mechanisms by which ROCK blockade causes cardiac hypoplasia, we assessed programmed cell death and cell proliferation in the hearts. We found decreased cell proliferation in the Y27632-treated hearts, but no changes in programmed cell death. We further observed that ROCK inhibition decreased cardiac myocyte proliferation, suggesting that ROCK kinases regulate cardiomyocyte division. To identify factors involved in ROCK action in regulation of cardiac cell division, we examined expression of cell cycle proteins by using Western blot analysis. We found that ROCK blockade decreased expression of cell cycle proteins, cyclin D3, CDK6, and p27(KIP1) in the hearts and cardiomyocytes, which are required for initiation of cell cycle and G1/S phase transition. These observations show that ROCK kinases play a role in cardiac development and that ROCK kinases regulate cardiac cell proliferation and cell cycle protein expression.
authors.affiliation: Yale Child Health Research Center, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520, USA. zhiyong.zhao@yale.edu
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhao
authors.forename: Scott A
authors.initials: SA
authors.lastname: Rivkees
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000096:biosynthesis; D002455:Cell Division; D056743:Cyclin D3; D051361:Cyclin-Dependent Kinase 6; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis; D016213:Cyclins / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase; D006321:Heart / Q000196:embryology* / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D009206:Myocardium / Q000166:cytology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D016196:S Phase; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis; D054460:rho-Associated Kinases
chemical_list: D000577:Amides; C534697:Ccnd3 protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D056743:Cyclin D3; D016213:Cyclins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D011725:Pyridines; D025521:Tumor Suppressor Proteins; C108830:Y 27632; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; C495912:Cdk6 protein, mouse; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases