TY - JOUR
T1 - Regulation of the versican promoter by the β-catenin-T-cell factor complex in vascular smooth muscle cells
AU - Rahmani, Maziar
AU - Read, Jason T.
AU - Carthy, Jon M.
AU - McDonald, Paul C.
AU - Wong, Brian W.
AU - Esfandiarei, Mitra
AU - Si, Xiaoning
AU - Luo, Zongshu
AU - Luo, Honglin
AU - Rennie, Paul S.
AU - McManus, Bruce M.
PY - 2005/4/1
Y1 - 2005/4/1
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=20144388953&partnerID=8YFLogxK
U2 - 10.1074/jbc.M411766200
DO - 10.1074/jbc.M411766200
M3 - Article
C2 - 15668231
AN - SCOPUS:20144388953
SN - 0021-9258
VL - 280
SP - 13019
EP - 13028
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 13
ER -