Heitzig Nicole, Brinkmann Benjamin F, Koerdt Sophia N, Rosso Gonzalo, Shahin Victor, Rescher Ursula
a Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, and Interdisciplinary Clinical Research Center , University of Münster , Münster , Germany.
b Institute of Physiology II , University of Münster , Münster , Germany.
Cell Adh Migr. 2017 May 4;11(3):275-287. doi: 10.1080/19336918.2016.1264559. Epub 2017 Jan 6.
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 Ca- 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.
血管生成的生理和病理过程依赖于精心编排的内皮细胞（EC）黏附、迁移以及新血管的形成。在此我们报告，膜联蛋白A8（AnxA8）缺陷的人脐静脉内皮细胞（HUVECs），膜联蛋白家族中一种结合钙和膜的蛋白成员，对血管内皮生长因子（VEGF）-A作出反应时，其出芽能力严重缺陷，并且在迁移以及黏附于β1整合素结合的细胞外基质（ECM）蛋白的能力方面严重受损。我们发现这些细胞在细胞表面形成包含四跨膜蛋白CD63、主要的VEGF-A受体VEGFR2以及β1整合素亚基的复合物方面存在缺陷。我们观察到，在VEGF-A激活AnxA8缺失的HUVECs后，VEGFR2的内化减少，VEGFR2的磷酸化增加，并且酪氨酸577磷酸化的粘着斑激酶（pFAK577）的空间分布发生改变。我们得出结论，AnxA8影响CD63/VEGFR2/β1整合素复合物的形成，导致VEGF-A信号转导通路的过度激活，并严重干扰VEGF-A驱动的血管生成出芽。
