Basic Research in Cardiology

, 109:404

Brag2 differentially regulates β1- and β3-integrin-dependent adhesion in endothelial cells and is involved in developmental and pathological angiogenesis

Authors

  • Yosif Manavski
    • Institute of Cardiovascular Regeneration, Goethe University Frankfurt
  • Guillaume Carmona
    • Institute of Cardiovascular Regeneration, Goethe University Frankfurt
    • David H Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology
  • Katrin Bennewitz
    • Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty MannheimHeidelberg University
  • Zhongshu Tang
    • State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat-Sen University
  • Fan Zhang
    • NEI, National Institutes of Health
  • Atsuko Sakurai
    • Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health
  • Andreas M. Zeiher
    • Department of Internal Medicine III, CardiologyGoethe University of Frankfurt
  • J. Silvio Gutkind
    • Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health
  • Xuri Li
    • State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat-Sen University
  • Jens Kroll
    • Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty MannheimHeidelberg University
    • Division of Vascular Oncology and MetastasisGerman Cancer Research Center (DKFZ-ZMBH Alliance)
  • Stefanie Dimmeler
    • Institute of Cardiovascular Regeneration, Goethe University Frankfurt
    • Department of Internal Medicine III, CardiologyGoethe University of Frankfurt
    • Institute of Cardiovascular Regeneration, Goethe University Frankfurt
Original Contribution

DOI: 10.1007/s00395-014-0404-2

Cite this article as:
Manavski, Y., Carmona, G., Bennewitz, K. et al. Basic Res Cardiol (2014) 109: 404. doi:10.1007/s00395-014-0404-2

Abstract

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 α5β1-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.

Keywords

AngiogenesisBrag2EndocytosisIntegrinsMigration

Supplementary material

395_2014_404_MOESM1_ESM.pdf (760 kb)
Supplementary material 1 (PDF 759 kb)
395_2014_404_MOESM2_ESM.docx (26 kb)
Supplementary material 2 (DOCX 26 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2014