title: IQGAP1 links PDGF receptor-β signal to focal adhesions involved in vascular smooth muscle cell migration: role in neointimal formation after vascular injury.
abstract: 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.
authors: Department of Pharmacology, Center for Lung and Vascular Biology, University of Illinois at Chicago, Chicago, Illinois;
authors: Takashi
authors: T
authors: Kohno
authors: Norifumi
authors: N
authors: Urao
authors: Takashi
authors: T
authors: Ashino
authors: Varadarajan
authors: V
authors: Sudhahar
authors: Hyoe
authors: H
authors: Inomata
authors: Minako
authors: M
authors: Yamaoka-Tojo
authors: Ronald D
authors: RD
authors: McKinney
authors: Tohru
authors: T
authors: Fukai
authors: Masuko
authors: M
authors: Ushio-Fukai
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D005263:Femoral Artery / Q000378:metabolism / Q000502:physiology; D022001:Focal Adhesions / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D058426:Neointima / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation / Q000502:physiology; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D057772:Vascular System Injuries / Q000378:metabolism / Q000473:pathology; D020703:ras GTPase-Activating Proteins / Q000378:metabolism*
chemical_list: C101203:IQ motif containing GTPase activating protein 1; D010982:Platelet-Derived Growth Factor; D020703:ras GTPase-Activating Proteins; D014443:Tyrosine; D020797:Receptor, Platelet-Derived Growth Factor beta
keywords: IQGAP1; migration; platelet-derived growth factor; vascular injury; vascular smooth muscle cell
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