Abstract 337: Alternative Angiogenic Pathway Driven by Stimulus-Dependent Phosphorylation of Profilin-1
Angiogenesis, the outgrowth of new blood vessels from pre-existing ones, is fundamental to development and post-injury tissue repair. Vascular endothelial growth factor (VEGF)-A guides and enhances directional endothelial cell (EC) migration to initiate angiogenesis, which can be driven by a multistep signaling cascade that directs actin polymerization. Profilin-1 (Pfn-1) is an actin-binding protein that enhances actin filament formation and cell migration, but stimulus-dependent regulation of Pfn-1 has not been observed. Here, we show that VEGF-A-inducible phosphorylation of Pfn-1 at Tyr129 is critical for EC migration and angiogenesis. Chemotactic activation of VEGF receptor kinase-2 (VEGFR2) and its immediate downstream kinase Src directly induce Pfn-1 phosphorylation in the cell leading edge, promoting Pfn-1 binding to actin and actin polymerization. Interestingly, Pfn-1 phosphorylation is robustly and preferentially elevated in blood vessels during tissue repair after myocardial infarction (MI) in humans. Conditional endothelial knock-in of phosphorylation-deficient Y129F Pfn-1 mutant in mice reveals that Pfn-1 phosphorylation is required for VEGF-A-induced EC sprouting migration and critical for angiogenesis in response to wounding and ischemic injury, but not for developmental angiogenesis. Thus, VEGFR2/Src-mediated phosphorylation of Pfn-1 bypasses canonical, multistep intracellular signaling events to initiate EC migration and angiogenesis, and may serve as a selective therapeutic target for angiogenesis-related disorders including ischemic heart disease.
- © 2012 by American Heart Association, Inc.