Abiko Hiyori, Fujiwara Sachiko, Ohashi Kazumasa, Hiatari Ryuichi, Mashiko Toshiya, Sakamoto Naoya, Sato Masaaki, Mizuno Kensaku
Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
J Cell Sci. 2015 May 1;128(9):1683-95. doi: 10.1242/jcs.157503. Epub 2015 Mar 20.
Cyclic stretch is an artificial model of mechanical force loading, which induces the reorientation of vascular endothelial cells and their stress fibers in a direction perpendicular to the stretch axis. Rho family GTPases are crucial for cyclic-stretch-induced endothelial cell reorientation; however, the mechanism underlying stretch-induced activation of Rho family GTPases is unknown. A screen of short hairpin RNAs targeting 63 Rho guanine nucleotide exchange factors (Rho-GEFs) revealed that at least 11 Rho-GEFs – Abr, alsin, ARHGEF10, Bcr, GEF-H1 (also known as ARHGEF2), LARG (also known as ARHGEF12), p190RhoGEF (also known as ARHGEF28), PLEKHG1, P-REX2, Solo (also known as ARHGEF40) and α-PIX (also known as ARHGEF6) – which specifically or broadly target RhoA, Rac1 and/or Cdc42, are involved in cyclic-stretch-induced perpendicular reorientation of endothelial cells. Overexpression of Solo induced RhoA activation and F-actin accumulation at cell-cell and cell-substrate adhesion sites. Knockdown of Solo suppressed cyclic-stretch- or tensile-force-induced RhoA activation. Moreover, knockdown of Solo significantly reduced cyclic-stretch-induced perpendicular reorientation of endothelial cells when cells were cultured at high density, but not when they were cultured at low density or pretreated with EGTA or VE-cadherin-targeting small interfering RNAs. These results suggest that Solo is involved in cell-cell-adhesion-mediated mechanical signal transduction during cyclic-stretch-induced endothelial cell reorientation.
周期性拉伸是一种机械力加载的人工模型，它可诱导血管内皮细胞及其应力纤维沿垂直于拉伸轴的方向重新定向。Rho家族GTP酶对于周期性拉伸诱导的内皮细胞重新定向至关重要；然而，拉伸诱导Rho家族GTP酶激活的潜在机制尚不清楚。一项针对63种Rho鸟嘌呤核苷酸交换因子（Rho-GEFs）的短发夹RNA筛选显示，至少11种Rho-GEFs——Abr、alsin、ARHGEF10、Bcr、GEF-H1（也称为ARHGEF2）、LARG（也称为ARHGEF12）、p190RhoGEF（也称为ARHGEF28）、PLEKHG1、P-REX2、Solo（也称为ARHGEF40）和α-PIX（也称为ARHGEF6）——特异性或广泛靶向RhoA、Rac1和/或Cdc42，参与了周期性拉伸诱导的内皮细胞垂直重新定向。Solo的过表达诱导了RhoA激活以及细胞间和细胞与底物粘附位点处的F-肌动蛋白积累。Solo的敲低抑制了周期性拉伸或拉力诱导的RhoA激活。此外，当细胞高密度培养时，敲低Solo显著降低了周期性拉伸诱导的内皮细胞垂直重新定向，但在低密度培养或用EGTA或靶向VE-钙粘蛋白的小干扰RNA预处理时则没有。这些结果表明，Solo参与了周期性拉伸诱导的内皮细胞重新定向过程中细胞间粘附介导的机械信号转导。
