title: Up-regulation of BMP-2 antagonizes TGF-β1/ROCK-enhanced cardiac fibrotic signalling through activation of Smurf1/Smad6 complex.
abstract: Rho-associated kinase (ROCK) plays a critical role in pressure overload-induced left ventricular remodelling. However, the underlying mechanism remains unclear. Here, we reported that TGF-β1-induced ROCK elevation suppressed BMP-2 level and strengthened fibrotic response. Exogenous BMP-2 supply effectively attenuated TGF-β1 signalling pathway through Smad6-Smurf-1 complex activation. In vitro cultured cardiomyocytes, mechanical stretch up-regulated cardiac TGF-β1, TGF-β1-dependent ROCK and down-regulated BMP-2, but BMP-2 level could be reversed through blocking TGF-β1 receptor by SB-431542 or inhibition of ROCK by Y-27632. TGF-β1 could also activate ROCK and suppress endogenous BMP-2 level in a dose-dependent manner. Knock-down BMP-2 enhanced TGF-β1-mediated PKC-δ and Smad3 signalling cascades. In contrast, treatment with Y-27632 or SB-431542, respectively suppressed ROCK-dependent PKC-δ and Smad3 activation, but BMP-2 was only up-regulated by Y-27632. In addition, BMP-2 silencing abolished the effect of Y-27632, but not SB-431542 on suppression of TGF-β1 pathway. Further experiments showed that Smad6 Smurf1 interaction were required for BMP-2-evoked antagonizing effects. Smad6 overexpression attenuated TGF-β1-induced activation of PKC-δ and Smad3, promoted TGF-β RI degradation in BMP-2 knock-down cardiomyocytes, and could be abolished after knocking-down Smurf-1, in which Smad6/Smurf1 complex formation was critically involved. In vivo data showed that pressure overload-induced collagen deposition was attenuated, cardiac function was improved and TGF-β1-dependent activation of PKC-δ and Smad3 was reduced after 2 weeks treatment with rhBMP-2(0.5 mg/kg) or Y-27632 (10 mg/kg) in mice that underwent surgical transverse aortic constriction. In conclusion, we propose that BMP-2, as a novel fibrosis antagonizing cytokine, may have potential beneficial effect in attenuating pressure overload-induced cardiac fibrosis.
authors.affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital and Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
authors.forename: Shijun
authors.initials: S
authors.lastname: Wang
authors.forename: Aijun
authors.initials: A
authors.lastname: Sun
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.forename: Jianguo
authors.initials: J
authors.lastname: Jia
authors.forename: Keqiang
authors.initials: K
authors.lastname: Wang
authors.forename: Junbo
authors.initials: J
authors.lastname: Ge
authors.forename: Yunzeng
authors.initials: Y
authors.lastname: Zou
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004149:Dioxoles / Q000494:pharmacology; D005355:Fibrosis; D055785:Gene Knockdown Techniques; D006321:Heart / Q000503:physiopathology; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D017423:Sequence Analysis, RNA; D015398:Signal Transduction; D051905:Smad6 Protein / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D000577:Amides; D001549:Benzamides; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D004149:Dioxoles; D011725:Pyridines; D051905:Smad6 Protein; C497803:Smad6 protein, mouse; D053773:Transforming Growth Factor beta1; C108830:Y 27632; C492381:Smurf1 protein, mouse; D044767:Ubiquitin-Protein Ligases; D054460:rho-Associated Kinases; D051745:Protein Kinase C-delta