AIP1 functions as an endogenous inhibitor of VEGFR2-mediated signaling and inflammatory angiogenesis in mice.
ASK1-interacting protein-1 (AIP1), a recently identified member of the Ras GTPase-activating protein family, is highly expressed in vascular ECs and regulates EC apoptosis in vitro. However, its function in vivo has not been established. To study this, we generated AIP1-deficient mice (KO mice). Although these mice showed no obvious defects in vascular development, they exhibited dramatically enhanced angiogenesis in 2 models of inflammatory angiogenesis. In one of these models, the enhanced angiogenesis observed in the KO mice was associated with increased VEGF-VEGFR2 signaling. Consistent with this, VEGF-induced ear, cornea, and retina neovascularization were greatly augmented in KO mice and the enhanced retinal angiogenesis was markedly diminished by overexpression of AIP1. In vitro, VEGF-induced EC migration was inhibited by AIP1 overexpression, whereas it was augmented by both AIP1 knockout and knockdown, with the enhanced EC migration caused by AIP1 knockdown being associated with increased VEGFR2 signaling. We present mechanistic data that suggest AIP1 is recruited to the VEGFR2-PI3K complex, binding to both VEGFR2 and PI3K p85, at a late phase of the VEGF response, and that this leads to inhibition of VEGFR2 signaling. Taken together, our data demonstrate that AIP1 functions as an endogenous inhibitor in VEGFR2-mediated adaptive angiogenesis in mice.
Zhang
Haifeng
H
Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
He
Yun
Y
Dai
Shengchuan
S
Xu
Zhe
Z
Luo
Yan
Y
Wan
Ting
T
Luo
Dianhong
D
Jones
Dennis
D
Tang
Shibo
S
Chen
Hong
H
Sessa
William C
WC
Min
Wang
W
D000818:Animals; D002417:Cattle; D002465:Cell Movement / Q000235:genetics; D016510:Corneal Neovascularization / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism; D020703:ras GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*
D042461:Vascular Endothelial Growth Factor A; D020703:ras GTPase-Activating Proteins; C467480:vascular endothelial growth factor A, mouse; D019869:Phosphatidylinositol 3-Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2