Clark Craig B, McKnight Nathan L, Frangos John A
Department of Bioengineering, University of California San Diego, 92093-0142, La Jolla, CA, USA.
Biochem Biophys Res Commun. 2002 Nov 29;299(2):258-62. doi: 10.1016/s0006-291x(02)02628-1.
The endothelium is known to sense and respond to its physical environment, but the underlying mechanisms and early events of endothelial cell mechanotransduction are not well understood. The present study measured G protein activation by mechanical strain in human umbilical vein endothelial cells (HUVEC) directly by photoincorporation of a hydrolysis resistant, radiolabeled GTP analog. Ten percent uniaxial strain at a strain rate of 20% s(-1) over 1min activated a 38kDa Galpha subunit 167+/-17% relative to controls, while 2% cyclic strain failed to significantly activate the protein (117+/-19%). A single cycle of 10% strain at 20% s(-1) strain rate activated the Galpha subunit 152+/-25%, while activation at the same strain but lower strain rate (0.3% s(-1)) was not significantly different from controls (116+/-12%). Western blot analysis identified the 38kDa protein as Galpha(q/11). These results demonstrate the rapid activation of G proteins in HUVEC by cyclic uniaxial strain in a strain- and strain rate-dependent manner.
已知内皮细胞能够感知并响应其物理环境，但内皮细胞机械转导的潜在机制和早期事件尚未完全明确。本研究通过对一种抗水解的放射性标记GTP类似物进行光掺入，直接测量了人脐静脉内皮细胞（HUVEC）中机械应变引起的G蛋白激活。在1分钟内以20% s(-1)的应变率施加10%的单轴应变，相对于对照组，激活了一个38kDa的Gα亚基，激活程度为167±17%，而2%的循环应变未能显著激活该蛋白（117±19%）。以20% s(-1)的应变率施加一个10%应变的单循环，激活Gα亚基的程度为152±25%，而在相同应变但较低应变率（0.3% s(-1)）下激活程度与对照组无显著差异（116±12%）。蛋白质印迹分析确定该38kDa蛋白为Gα(q/11)。这些结果表明，循环单轴应变能以应变和应变率依赖的方式快速激活HUVEC中的G蛋白。
