Kawase Kazuho, Nakamura Takeshi, Takaya Akiyuki, Aoki Kazuhiro, Namikawa Kazuhiko, Kiyama Hiroshi, Inagaki Shuichiro, Takemoto Hiroshi, Saltiel Alan R, Matsuda Michiyuki
Department of Signal Transduction, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
Dev Cell. 2006 Sep;11(3):411-21. doi: 10.1016/j.devcel.2006.07.008.
TC10, a Rho family GTPase, has been shown to play an important role in the exocytosis of GLUT4 and other proteins, primarily by tethering the vesicles at the plasma membrane. Using a newly developed probe based on fluorescence resonance energy transfer, we found that TC10 activity at tethered vesicles dropped immediately before vesicle fusion in HeLa cells stimulated with epidermal growth factor (EGF), suggesting that GTP hydrolysis by TC10 is a critical step in vesicle fusion. In support of this model, a GTPase-deficient TC10 mutant potently inhibited EGF-induced vesicular fusion in HeLa cells and depolarization-induced neuronal secretion. Furthermore, we found that GTP hydrolysis by TC10 in the vicinity of the plasma membrane was dependent on Rac and the redox-regulated Rho GAP, p190RhoGAP-A. We propose that an EGF-stimulated GAP accelerates GTP hydrolysis of TC10, thereby promoting vesicle fusion.
Rho家族GTP酶TC10已被证明在GLUT4及其他蛋白质的胞吐过程中发挥重要作用，主要是通过将囊泡拴系在质膜上。使用一种新开发的基于荧光共振能量转移的探针，我们发现，在用表皮生长因子（EGF）刺激的HeLa细胞中，拴系囊泡处的TC10活性在囊泡融合前立即下降，这表明TC10催化的GTP水解是囊泡融合的关键步骤。作为该模型的证据，一种GTP酶缺陷型TC10突变体可有效抑制HeLa细胞中EGF诱导的囊泡融合以及去极化诱导的神经元分泌。此外，我们发现质膜附近的TC10催化的GTP水解依赖于Rac和氧化还原调节的Rho GAP，即p190RhoGAP-A。我们提出，EGF刺激的GAP加速了TC10的GTP水解，从而促进了囊泡融合。
