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Induction of the matricellular protein CCN1 through RhoA and MRTF-A contributes to ischemic cardioprotection.

ABSTRACT: Activation of RhoA, a low molecular-weight G-protein, plays an important role in protecting the heart against ischemic stress. Studies using non-cardiac cells demonstrate that the expression and subsequent secretion of the matricellular protein CCN1 is induced by GPCR agonists that activate RhoA. In this study we determined whether and how CCN1 is induced by GPCR agonists in cardiomyocytes and examined the role of CCN1 in ischemic cardioprotection in cardiomyocytes and the isolated perfused heart. In neonatal rat ventricular myocytes (NRVMs), sphingosine 1-phosphate (S1P), lysophosphatidic acid (LPA) and endothelin-1 induced robust increases in CCN1 expression while phenylephrine, isoproterenol and carbachol had little or no effect. The ability of agonists to activate the small G-protein RhoA correlated with their ability to induce CCN1. CCN1 induction by S1P was blocked when RhoA function was inhibited with C3 exoenzyme or a pharmacological RhoA inhibitor. Conversely overexpression of RhoA was sufficient to induce CCN1 expression. To delineate the signals downstream of RhoA we tested the role of MRTF-A (MKL1), a co-activator of SRF, in S1P-mediated CCN1 expression. S1P increased the nuclear accumulation of MRTF-A and this was inhibited by the functional inactivation of RhoA. In addition, pharmacological inhibitors of MRTF-A or knockdown of MRTF-A significantly diminished S1P-mediated CCN1 expression, indicating a requirement for RhoA/MRTF-A signaling. We also present data indicating that CCN1 is secreted following agonist treatment and RhoA activation, and binds to cells where it can serve an autocrine function. To determine the functional significance of CCN1 expression and signaling, simulated ischemia/reperfusion (sI/R)-induced apoptosis was assessed in NRVMs. The ability of S1P to protect against sI/R was significantly reduced by the inhibition of RhoA, ROCK or MRTF-A or by CCN1 knockdown. We also demonstrate that ischemia/reperfusion induces CCN1 expression in the isolated perfused heart and that this functions as a cardioprotective mechanism, evidenced by the significant increase in infarct development in response to I/R in the cardiac specific CCN1 KO relative to control mice. Our findings implicate CCN1 as a mediator of cardioprotection induced by GPCR agonists that activate RhoA/MRTF-A signaling.

SUBMITTER: Zhao X

PROVIDER: S-EPMC4157956 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Induction of the matricellular protein CCN1 through RhoA and MRTF-A contributes to ischemic cardioprotection.

Zhao Xia X Ding Eric Y EY Yu Olivia M OM Xiang Sunny Y SY Tan-Sah Valerie P VP Yung Bryan S BS Hedgpeth Joe J Neubig Richard R RR Lau Lester F LF Brown Joan Heller JH Miyamoto Shigeki S

Journal of molecular and cellular cardiology 20140808

Activation of RhoA, a low molecular-weight G-protein, plays an important role in protecting the heart against ischemic stress. Studies using non-cardiac cells demonstrate that the expression and subsequent secretion of the matricellular protein CCN1 is induced by GPCR agonists that activate RhoA. In this study we determined whether and how CCN1 is induced by GPCR agonists in cardiomyocytes and examined the role of CCN1 in ischemic cardioprotection in cardiomyocytes and the isolated perfused hear ...[more]

PMID: 25106095

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Project description:Effects of the matricellular protein CCN1 on macrophage inflammatory gene expression was tested in a macrophage cell line I-13.35. CCN1 (CYR61) is a matricellular protein that is highly expressed at sites of inflammation and wound repair. In these contexts, CCN1 can modify the activities of specific cytokines, enabling TNF-alpha to be cytotoxic without blocking NFkB activity and enhancing the apoptotic activity of FasL and TRAIL. Here we show that CCN1 supports the adhesion of macrophages through integrin alphaMbeta2 and syndecan-4, activates NFkB-mediated transcription, and induces a pro-inflammatory genetic program characteristic of classically activated M1 macrophages that participates in Th1 responses. The effects of CCN1 include upregulation of cytokines (TNFa, IL-1a, IL-1b, IL-6, IL-12b), chemokines (MIP-1a, MCP-3, Gro1, Gro2, IP-10), regulators of oxidative stress and complement (iNOS, C3), and downregulation of specific receptors (TLR4, IL-10rb) and anti-inflammatory factors (TGF-b1). CCN1 regulates this genetic program through at least two distinct mechanisms: an immediate-early response resulting from direct activation of NFkB by CCN1, leading to the synthesis of cytokines including TNFa and IP-10; and a delayed response resulting from CCN1-induced TNFa, which acts as an autocrine/paracrine mediator to activate the expression of other cytokines including IL-1b and IL-6. These results identify CCN1 as a novel component of the extracellular matrix that activates pro-inflammatory genes in macrophages, implicating its role in regulating macrophage function during inflammation. Macrophage cell line I-13.35 (from Tlr4-defective C3H/HeJ) was treated with purified recombinant CCN1 protein for 6 hr. Total RNA was isolated, converted to cRNA probes, and hybridized to a oligonucleotide array representing 113 murine inflammation-related genes (from SA Biosciences at www.sabiosciences.com, Cat. Number OMM-011.) The array is a nylon membrane based DNA microarray on which 60-mer oligonucleotides probes were printed. Gene expression profile of resting cells incubated in serum-free medium (containing albumin, BSA) was used as a control for basal levels of gene expression.

Dataset Information

Induction of the matricellular protein CCN1 through RhoA and MRTF-A contributes to ischemic cardioprotection.

Publications

Induction of the matricellular protein CCN1 through RhoA and MRTF-A contributes to ischemic cardioprotection.

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