tailieunhanh - Báo cáo khoa học: Regulation of connective tissue growth factor (CTGF/CCN2) gene transcription and mRNA stability in smooth muscle cells Involvement of RhoA GTPase and p38 MAP kinase and sensitivity to actin dynamics

Connective tissue growth factor (CTGF/CCN2) is an immediate early gene-encoded polypeptide modulating cell growth and collagen synthesis. The importance of CTGF/ CCN2 function is highlighted by its disregulation in fibrotic disorders. In this study, we investigated the regulation and signaling pathways that are required for various stimuli of intracellular signaling events to induce the expression of the endogenous CTGF/CCN2gene in smooth muscle cells. | Eur. J. Biochem. 271 4436-4450 2004 FEBS 2004 doi Regulation of connective tissue growth factor CTGF CCN2 gene transcription and mRNA stability in smooth muscle cells Involvement of RhoA GTPase and p38 MAP kinase and sensitivity to actin dynamics Ibrul Chowdhury1 and Brahim Chaqour2 1 Department of Anatomy and Cell Biology University of Pennsylvania PA USA department of Anatomy and Cell Biology State University of New York SUNY Downstate Medical Center Brooklyn NY USA Connective tissue growth factor CTGF CCN2 is an immediate early gene-encoded polypeptide modulating cell growth and collagen synthesis. The importance of CTGF CCN2 function is highlighted by its disregulation in fibrotic disorders. In this study we investigated the regulation and signaling pathways that are required for various stimuli of intracellular signaling events to induce the expression of the endogenous CTGF CCN2 gene in smooth muscle cells. Incubation with the bioactive lysolipid sphingosine 1-phos-phate S1P produced a threefold increase whereas stimulation with either fetal bovine serum or anisomycin induced an even stronger activation eightfold of CTGF CCN2 expression. Using a combination of pathway-specific inhibitors and mutant forms of signaling molecules we found that S1P- and fetal bovine serum-induced CTGF CCN2 expression were dependent on both RhoA GTPase and p38 mitogen-activated protein kinase transduction pathways whereas the effects of anisomycin largely involved p38 and phosphatidyl inositol 3-kinase signaling mechanisms. However activation via these signaling events was absolutely dependent on actin cytoskeleton integrity. In particular RhoA-dependent regulation of the CTGF CCN2 gene was concomitant to increased polymerization of actin microfilaments resulting in decreased G- to F-actin ratio and appeared to be achieved at the transcriptional level. The p38 signaling pathway was RhoA-independent and led to CTGF CCN2 mRNA stabilization. Use of .