Endothelial cell (EC) migration is a key event for endothelial wound repair and angiogenesis. VEGF is a potent stimulator for EC migration primarily through the VEGF type2 receptor (VEGFR2). In quiescent ECs, one of the initial responses to stimulate endothelial migration by VEGF is the loosening of stable cell-cell contacts which is regulated by tyrosine phosphorylation of VE-cadherin. We showed that VEGF stimulates Rac1-dependent gp91phox-based NAD(P)H oxidase and that reactive oxygen species (ROS) are involved in VEGFR2-mediated signaling linked to EC migration. Underlying molecular mechanisms are poorly understood. We recently identified IQGAP1 as a novel VEGFR2 binding protein. It functions as a scaffold protein that controls cell motility and morphogenesis by interacting with cytoskeletal and cell-cell adhesion proteins including active Rac1 and E-cadherin. We also found that: 1) IQGAP1 expression is increased in the newly-formed capillary ECs in a mouse hindlimb ischemia model of angiogenesis; 2) Overexpression of IQGAP1 increases basal Rac1 activity, ROS production and cell migration in ECs; 3) VEGF promotes recruitment of activated VEGFR2 and Rac1 to the IQGAP1-VE-cadherin complex at adherens junctions, which may promote ROS-dependent loss of cell-cell contacts and subsequent EC migration; 4) Wound assays reveal that IQGAP1 colocalizes with active VEGFR2 and gp91phox at the leading edge inactively migrating ECs. We thus hypothesize that IQGAP1 functions as a VEGFR2 binding scaffold protein to link ROS-dependent signaling with VEGF-mediated endothelial migration.
Aim1 will examine whether IQGAP1 functionally interacts with VEGFR2 and Rac1 to couple VEGFR2 to ROS-dependent signaling linked to EC migration.
Aim2 will examine whether IQGAP1 functions as a scaffold to recruit activated VEGFR2 and Rac1 to adherens junctions through binding to VE-cadherin, thereby facilitating ROS-dependent loss of cell-cell contacts, which initiates EC migration.
Aim3 will examine the scaffolding role of IQGAP1 in targeting VEGFR2 and NAD(P)H oxidase to the leading edge during directed cell migration.
Aim4 will assess the functional significance of IQGAP1 in vivo using mouse hindlimb ishcemia model. The long-term goal is to understand the molecular mechanisms by which ROS regulate EC migration in the context of angiogenesis and endothelial wound repair, which should facilitate the development of new therapeutic strategies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL077524-03
Application #
7379914
Study Section
Vascular Cell and Molecular Biology Study Section (VCMB)
Program Officer
Schwartz, Lisa
Project Start
2006-03-15
Project End
2011-02-28
Budget Start
2008-03-01
Budget End
2009-02-28
Support Year
3
Fiscal Year
2008
Total Cost
$376,263
Indirect Cost
Name
University of Illinois at Chicago
Department
Pharmacology
Type
Schools of Medicine
DUNS #
098987217
City
Chicago
State
IL
Country
United States
Zip Code
60612
Sudhahar, Varadarajan; Okur, Mustafa Nazir; Bagi, Zsolt et al. (2018) Akt2 (Protein Kinase B Beta) Stabilizes ATP7A, a Copper Transporter for Extracellular Superoxide Dismutase, in Vascular Smooth Muscle: Novel Mechanism to Limit Endothelial Dysfunction in Type 2 Diabetes Mellitus. Arterioscler Thromb Vasc Biol 38:529-541
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Chen, Gin-Fu; Sudhahar, Varadarajan; Youn, Seock-Won et al. (2015) Copper Transport Protein Antioxidant-1 Promotes Inflammatory Neovascularization via Chaperone and Transcription Factor Function. Sci Rep 5:14780
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Kohno, Takashi; Urao, Norifumi; Ashino, Takashi et al. (2013) Novel role of copper transport protein antioxidant-1 in neointimal formation after vascular injury. Arterioscler Thromb Vasc Biol 33:805-13
Sudhahar, Varadarajan; Urao, Norifumi; Oshikawa, Jin et al. (2013) Copper transporter ATP7A protects against endothelial dysfunction in type 1 diabetic mice by regulating extracellular superoxide dismutase. Diabetes 62:3839-50
Urao, Norifumi; Ushio-Fukai, Masuko (2013) Redox regulation of stem/progenitor cells and bone marrow niche. Free Radic Biol Med 54:26-39
Kohno, Takashi; Urao, Norifumi; Ashino, Takashi et al. (2013) IQGAP1 links PDGF receptor-? signal to focal adhesions involved in vascular smooth muscle cell migration: role in neointimal formation after vascular injury. Am J Physiol Cell Physiol 305:C591-600

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