Department of Medicine, University of Alberta, Edmonton, AB, Canada T6G 2S2.
Arterioscler Thromb Vasc Biol. 2012 Nov;32(11):2694-701. doi: 10.1161/ATVBAHA.112.300074. Epub 2012 Aug 23.
The function of the endothelial cell (EC)-enriched Rho family guanine nucleotide exchange factor, facio-genital dysplasia-5 (FGD5), is poorly understood. We sought to determine whether FGD5 regulates endothelial cytoskeletal reorganization and angiogenesis.
We observed that FGD5 is expressed in primary human EC isolated from sites across the vasculature. Inhibition of FGD5 expression using RNA interference decreased the protein by ≈70%. In 3-dimensional vascular endothelial growth factor-stimulated angiogenesis in vitro, FGD5-deficient endothelial sprout protrusion was markedly blunted versus nonsilenced controls. FGD5 knockdown impaired adhesion to fibronectin and collagen IV and remodeling of matrix adhesion complexes. Similarly, monolayer electric impedance was decreased, and impedance increased at a slower rate after seeding FGD5-deficient cells versus controls, reflecting decreased EC spreading. Further, FGD5 plays a role in cell survival, because expression of cleaved caspase-3 was increased in FGD5-deficient EC after loss of cell-matrix contacts, and proapoptotic tumor necrosis factor-α stimulation elicited EC with subdiploid DNA content among FGD5-deficient EC. Mechanistically, the phosphatidylinositol 3-kinase/Akt pathway that regulates both adhesive and survival signal transduction pathways requires FGD5. Vascular endothelial growth factor-stimulated Akt phosphorylation and downstream forkhead box protein-O1 inactivation is inhibited by FGD5 loss.
FGD5 regulates endothelial adhesion, survival, and angiogenesis by modulating phosphatidylinositol 3-kinase signaling.
内皮细胞（EC）丰富的Rho 家族鸟嘌呤核苷酸交换因子——面肩肱型肌营养不良蛋白 5（FGD5）的功能尚未完全阐明。本研究旨在确定 FGD5 是否调节内皮细胞细胞骨架重排和血管生成。
我们观察到 FGD5 表达于源自血管系统不同部位的原代人 EC 中。使用 RNA 干扰抑制 FGD5 表达可使蛋白表达减少约 70%。在体外 3 维血管内皮生长因子刺激的血管生成中，FGD5 缺陷型内皮芽突突起明显比非沉默对照显著减弱。FGD5 敲低会损害与纤维连接蛋白和胶原蛋白 IV 的黏附以及基质黏附复合物的重塑。同样，单层电阻抗降低，并且与对照相比，FGD5 缺陷型细胞接种后阻抗增加速度较慢，反映出 EC 铺展减少。此外，FGD5 在细胞存活中发挥作用，因为在失去细胞-基质接触后，FGD5 缺陷型 EC 中 cleaved caspase-3 的表达增加，并且促凋亡肿瘤坏死因子-α刺激可诱导 FGD5 缺陷型 EC 中具有亚二倍体 DNA 含量的细胞。从机制上讲，调节黏附和存活信号转导途径的磷脂酰肌醇 3-激酶/Akt 途径需要 FGD5。FGD5 缺失会抑制血管内皮生长因子刺激的 Akt 磷酸化和下游叉头框蛋白-O1 失活。
FGD5 通过调节磷脂酰肌醇 3-激酶信号转导来调节内皮细胞黏附、存活和血管生成。
