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PKCδ is necessary for Smad3 expression and TGFβ‐induced fibronectin synthesis in vascular smooth muscle cells
Author(s) -
Ryer Evan Joseph,
Hom R. Patrick,
Faries Peter L,
Kent K. Craig,
Liu Bo
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a981-b
Subject(s) - rottlerin , fibronectin , protein kinase c , vascular smooth muscle , microbiology and biotechnology , transforming growth factor , extracellular matrix , chemistry , signal transduction , biology , endocrinology , smooth muscle
Objective Production of extracellular matrix (ECM) by vascular smooth muscle cells (SMCs) is critical for the development of intimal hyperplasia (IH), a process that leads to failure of vascular reconstructions. TGFβ is a potent mediator of ECM synthesis including fibronectin (FN), a matrix glycoprotein abundant in IH. The purpose of these studies is to investigate the mechanism by which TGFβ regulates the synthesis of fibronectin. Methods and Results TGFβ induced FN protein and mRNA in A10 rat aortic SMCs. Overexpression of Smad3 in A10 SMCs via adenoviral transfection stimulated both basal and TGFβ induced FN protein and mRNA, while ectopic expression of Smad7 eliminated the TGFβ response. To understand the downstream signals from the TGFβ receptor, we manipulated PKCδ, a ubiquitous kinase and intermediate for various cytokine receptors. Inhibition of PKCδ using the chemical inhibitor rottlerin or dominant negative adenovirus (AdPKCδ DN) blocked TGFβ's induction of FN protein and mRNA. Moreover, aortic SMCs isolated from PKCδ −/ − mice exhibited diminished FN induction in response to TGFβ. Furthermore, we found Smad3 protein and mRNA levels markedly reduced in AdPKCδ DN‐treated A10 cells and in PKCδ −/ − SMCs. Finally, restoring Smad3 in rottlerin‐treated A10 SMCs rescued the ability of TGFβ to upregulate FN protein and mRNA expression. Conclusion Our data suggest that both PKCδ and Smad3 are required for induction of FN by TGFβ. Furthermore, PKCδ regulates FN expression, at least in part, through maintaining normal expression of Smad3. PKCδ may be a novel target for treating the fibroproliferative response after arterial injury.