Open AccessIQGAP1 links PDGF receptor-β signal to focal adhesions involved in vascular smooth muscle cell migration: role in neointimal formation after vascular injury
Author(s) -
Takashi Kohno,
Norifumi Urao,
Takashi Ashino,
Sudhahar Varadarajan,
Hyoe Inomata,
Minako YamaokaTojo,
Ronald McKinney,
Tohru Fukai,
Masuko Ushio–Fukai
Publication year - 2013
Publication title -
american journal of physiology. cell physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.432
H-Index - 181
eISSN - 1522-1563
pISSN - 0363-6143
DOI - 10.1152/ajpcell.00011.2013
Subject(s) - platelet derived growth factor receptor , iqgap1 , microbiology and biotechnology , vascular smooth muscle , cell migration , tyrosine phosphorylation , platelet derived growth factor , phosphorylation , signal transduction , cancer research , chemistry , biology , scaffold protein , growth factor , receptor , medicine , endocrinology , cell , biochemistry , smooth muscle
Platelet-derived growth factor (PDGF) stimulates vascular smooth muscle cell (VSMC) migration and neointimal formation in response to injury. We previously identified IQ-domain GTPase-activating protein 1 (IQGAP1) as a novel VEGF receptor 2 binding scaffold protein involved in endothelial migration. However, its role in VSMC migration and neointimal formation in vivo is unknown. Here we show that PDGF stimulation rapidly promotes IQGAP1 association with PDGF receptor-β (PDGFR) as well as IQGAP1 tyrosine phosphorylation in cultured VSMC. Overexpression or knockdown of IQGAP1 enhances or inhibits PDGFR autophosphorylation (p-PDGFR), respectively. Immunofluorescence and cell fractionation analysis reveals that PDGF-induced p-PDGFR localized in focal adhesions (FAs), but not caveolae/lipid rafts, is inhibited by IQGAP1 knockdown with siRNA. PDGF stimulation promotes IQGAP1 association with PDGFR/FA signaling protein complex. Functionally, IQGAP1 siRNA inhibits PDGF-induced FA formation as well as VSMC migration induced by PDGF. In vivo, IQGAP1 expression is markedly increased at neointimal VSMC in wire-injured femoral arteries. Mice lacking IQGAP1 exhibit impaired neointimal formation in response to vascular injury. In summary, IQGAP1, through interaction with PDGFR and FA signaling proteins, promotes activation of PDGFR in FAs as well as FA formation, which may contribute to VSMC migration and neointimal formation after injury. Our findings provide insight into IQGAP1 as a potential therapeutic target for vascular migration-related diseases.