title: Annexin A8 promotes VEGF-A driven endothelial cell sprouting.
abstract: The physiological and pathological process of angiogenesis relies on orchestrated endothelial cell (EC) adhesion, migration and formation of new vessels. Here we report that human umbilical vein endothelial cells (HUVECs) deficient in Annexin A8 (AnxA8), a member of the annexin family of Ca2+- and membrane binding proteins, are strongly deficient in their ability to sprout in response to vascular endothelial growth factor (VEGF)-A, and are strongly impaired in their ability to migrate and adhere to β1 integrin-binding extracellular matrix (ECM) proteins. We find that these cells are defective in the formation of complexes containing the tetraspanin CD63, the main VEGF-A receptor VEGFR2, and the β1 integrin subunit, on the cell surface. We observe that upon VEGF-A activation of AnxA8-depleted HUVECs, VEGFR2 internalization is reduced, phosphorylation of VEGFR2 is increased, and the spatial distribution of Tyr577-phosphorylated focal adhesion kinase (pFAK577) is altered. We conclude that AnxA8 affects CD63/VEGFR2/β1 integrin complex formation, leading to hyperactivation of the VEGF-A signal transduction pathway, and severely disturbed VEGF-A-driven angiogenic sprouting.
authors.affiliation: a Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center , University of Münster , Münster , Germany.
authors.forename: Nicole
authors.identifier: 0000-0003-1710-0406
authors.initials: N
authors.lastname: Heitzig
authors.affiliation: a Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center , University of Münster , Münster , Germany.
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Brinkmann
authors.affiliation: a Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center , University of Münster , Münster , Germany.
authors.forename: Sophia N
authors.identifier: 0000-0001-6392-8138
authors.initials: SN
authors.lastname: Koerdt
authors.affiliation: b Institute of Physiology II , University of Münster , Münster , Germany.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Rosso
authors.affiliation: b Institute of Physiology II , University of Münster , Münster , Germany.
authors.forename: Victor
authors.initials: V
authors.lastname: Shahin
authors.affiliation: a Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center , University of Münster , Münster , Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Rescher
mesh_terms: D017302:Annexins / Q000235:genetics* / Q000378:metabolism; D002448:Cell Adhesion / Q000235:genetics*; D042783:Endothelial Cells / Q000378:metabolism; D005109:Extracellular Matrix; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics; D046912:Multiprotein Complexes / Q000235:genetics; D009389:Neovascularization, Pathologic / Q000235:genetics*; D018919:Neovascularization, Physiologic / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D059470:Tetraspanins / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics
chemical_list: D017302:Annexins; D019012:Integrin beta1; D046912:Multiprotein Complexes; C508125:TSPAN1 protein, human; D059470:Tetraspanins; D042461:Vascular Endothelial Growth Factor A; C000588866:KDR protein, human; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: Annexin A8; CD63; HUVEC; VEGFR2; angiogenesis; endothelial cell sprouting; invasion; proximity ligation assay; tetraspanin; β1 integrin