Beta3 integrin-mediated ubiquitination activates survival signaling during myocardial hypertrophy.
Identifying the molecular mechanisms activated in compensatory hypertrophy and absent during decompensation will provide molecular targets for prevention of heart failure. We have previously shown enhanced ubiquitination (Ub) during the early growth period of pressure overload (PO) hypertrophy near intercalated discs of cardiomyocytes, where integrins are important for mechanotransduction. In this study, we tested the role of integrins upstream of Ub, whether enhanced Ub contributes to survival signaling in early PO, and if loss of this mechanism could lead to decreased ventricular function. The study used a beta(3) integrin (-/-) mouse and a wild-type mouse as a control for in vivo PO by transverse aortic constriction (TAC) and for cultured cardiomyocytes in vitro, stimulated with the integrin-activating peptide RGD. We demonstrate beta(3) integrin mediates transient Ub of targeted proteins during PO hypertrophy, which is necessary for cardiomyocyte survival and to maintain ventricular function. Prosurvival signaling proceeds by initiation of NF-kappaB transcription of the E3 ligase, cIAP1. In PO beta(3)(-/-) mice, absence of this mechanism correlates with increased TUNEL staining and decreased ventricular mass and function by 4 wk. This is the first study to show that a beta(3) integrin/Ub/NF-kappaB pathway contributes to compensatory hypertrophic growth.
Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina 29425-2221, USA.
Rebecca K
RK
Johnston
Sundaravadivel
S
Balasubramanian
Harinath
H
Kasiganesan
Catalin F
CF
Baicu
Michael R
MR
Zile
Dhandapani
D
Kuppuswamy
D000818:Animals; D006332:Cardiomegaly / Q000209:etiology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002415:Cats; D002470:Cell Survival; D002478:Cells, Cultured; D020672:I-kappa B Proteins / Q000378:metabolism; D051034:Inhibitor of Apoptosis Proteins / Q000096:biosynthesis / Q000235:genetics; D039661:Integrin beta3 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008955:Models, Cardiovascular; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D015398:Signal Transduction; D015533:Transcriptional Activation; D054875:Ubiquitination / Q000502:physiology*
D020672:I-kappa B Proteins; D051034:Inhibitor of Apoptosis Proteins; D039661:Integrin beta3; D016328:NF-kappa B; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid