Brag2 differentially regulates beta1- and beta3-integrin-dependent adhesion in endothelial cells and is involved in developmental and pathological angiogenesis
- Authors
- Manavski, Y., Carmona, G., Bennewitz, K., Tang, Z., Zhang, F., Sakurai, A., Zeiher, A.M., Gutkind, J.S., Li, X., Kroll, J., Dimmeler, S., and Chavakis, E.
- ID
- ZDB-PUB-140502-12
- Date
- 2014
- Source
- Basic Research in Cardiology 109(2): 404 (Journal)
- Registered Authors
- Kroll, Jens
- Keywords
- Angiogenesis, Brag2, Endocytosis, Integrins, Migration
- MeSH Terms
-
- RNA, Small Interfering/genetics
- Animals, Genetically Modified
- Integrin alphaVbeta3/genetics
- Integrin alphaVbeta3/metabolism
- Human Umbilical Vein Endothelial Cells
- ADP-Ribosylation Factors/metabolism
- Chlorocebus aethiops
- Neovascularization, Pathologic/genetics
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/physiopathology*
- Animals
- Neovascularization, Physiologic/genetics
- Neovascularization, Physiologic/physiology
- Retinopathy of Prematurity/genetics
- Retinopathy of Prematurity/metabolism
- Retinopathy of Prematurity/physiopathology*
- Integrin beta3/metabolism*
- Receptors, Vitronectin/genetics
- Receptors, Vitronectin/metabolism
- Disease Models, Animal
- COS Cells
- Cell Movement/physiology
- Humans
- Vascular Endothelial Growth Factor A/metabolism
- Guanine Nucleotide Exchange Factors/genetics*
- Guanine Nucleotide Exchange Factors/metabolism
- Integrin beta1/metabolism*
- Cell Adhesion/physiology*
- Mice, Inbred C57BL
- Zebrafish
- Choroidal Neovascularization/genetics
- Choroidal Neovascularization/metabolism
- Choroidal Neovascularization/physiopathology
- PubMed
- 24522833 Full text @ Basic Res. Cardiol.
β1-Integrins are essential for angiogenesis. The mechanisms regulating integrin function in endothelial cells (EC) and their contribution to angiogenesis remain elusive. Brag2 is a guanine nucleotide exchange factor for the small Arf-GTPases Arf5 and Arf6. The role of Brag2 in EC and angiogenesis and the underlying molecular mechanisms remain unclear. siRNA-mediated Brag2-silencing reduced EC angiogenic sprouting and migration. Brag2-siRNA transfection differentially affected α5β1- and αVβ3-integrin function: specifically, Brag2-silencing increased focal/fibrillar adhesions and adhesion on β1-integrin ligands (fibronectin and collagen), while reducing the adhesion on the αVβ3-integrin ligand, vitronectin. Consistent with these results, Brag2-silencing enhanced surface expression of &alpha5β1-integrin, while reducing surface expression of αVβ3-integrin. Mechanistically, Brag2-mediated αVβ3-integrin-recycling and β1-integrin endocytosis and specifically of the active/matrix-bound α5β1-integrin present in fibrillar/focal adhesions (FA), suggesting that Brag2 contributes to the disassembly of FA via β1-integrin endocytosis. Arf5 and Arf6 are promoting downstream of Brag2 angiogenic sprouting, β1-integrin endocytosis and the regulation of FA. In vivo silencing of the Brag2-orthologues in zebrafish embryos using morpholinos perturbed vascular development. Furthermore, in vivo intravitreal injection of plasmids containing Brag2-shRNA reduced pathological ischemia-induced retinal and choroidal neovascularization. These data reveal that Brag2 is essential for developmental and pathological angiogenesis by promoting EC sprouting through regulation of adhesion by mediating β1-integrin internalization and link for the first time the process of β1-integrin endocytosis with angiogenesis.