Regulation of the versican promoter by the β-catenin-T-cell factor complex in vascular smooth muscle cells

Maziar Rahmani, Jason T. Read, Jon M. Carthy, Paul C. McDonald, Brian W. Wong, Mitra Esfandiarei, Xiaoning Si, Zongshu Luo, Honglin Luo, Paul S. Rennie, Bruce M. McManus

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

The proteoglycan versican is pro-atherogenic and central to vascular injury and repair events. We identified the signaling pathways and promoter elements involved in regulation of versican expression in vascular smooth muscle cells. Phosphatidylinositol 3-kinase inhibitor, LY294002, significantly decreased versican-luciferase (Luc) promoter activity and endogenous mRNA levels. We further examined the roles of protein kinase B and glycogen synthase kinase (GSK)-3β, downstream effectors of phosphatidylinositol 3-kinase, in the regulation of versican transcription. Co-transfection of dominant negative and constitutively active protein kinase B constructs with a versican-Luc construct decreased and increased promoter activity, respectively. Inhibition of GSK-3β activity by LiCl augmented accumulation of β-catenin and caused induction of versican-Luc activity as well as versican mRNA levels. β-Catenin has no DNA binding domain, therefore it cannot directly induce transcription of the versican promoter. Software analysis of the versican promoter revealed two potential binding sites for T-cell factors (TCFs), proteins that confer transcriptional activation of β-catenin. Electrophoretic mobility shift and supershift assays revealed specific binding of human TCF-4 and β-catenin to oligonucleotides corresponding to a potential TCF binding site in the versican promoter. In addition to binding assays, we directly assessed the dependence of versican promoter activity on TCF binding sites. Site-directed mutagenesis of the TCF site located -492 bp relative to the transcription start site markedly diminished versican-Luc activity. Co-transfection of TCF-4 with versican-Luc did not increase promoter activity, but addition of β-catenin and TCF-4 significantly stimulated basal versican promoter activity. Our findings suggest that versican transcription is predominantly mediated by the GSK-3β pathway via the β-catenin-TCF transcription factor complex in smooth muscle cells, wherein such regulation contributes to the normal or aberrant formation of provisional matrix in vascular injury and repair events.

Original languageEnglish
Pages (from-to)13019-13028
Number of pages10
JournalJournal of Biological Chemistry
Volume280
Issue number13
DOIs
StatePublished - Apr 1 2005
Externally publishedYes

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