Department of Cell and Developmental Biology, Dental Research Institute, Seoul National University, Seoul 110-749, Korea.
Exp Neurobiol. 2011 Mar;20(1):29-34. doi: 10.5607/en.2011.20.1.29. Epub 2011 Mar 31.
Rho small GTPases control multiple aspects of neuronal morphogenesis by regulating the assembly and organization of the actin cytoskeleton. Although they are negatively regulated by GTPase activating proteins (GAPs), the roles of RhoGAPs in the nervous system have not been fully investigated. Here we describe a characterization of Drosophila RhoGAP68F that is mainly expressed in the embryonic central nervous system. RNA in situ hybridization analysis showed that expression of RhoGAP68F is highly restricted to the embryonic brain and ventral nerve cord. Database search revealed that RhoGAP68F contains an N-terminal Sec14 domain and a C-terminal RhoGAP domain. Rho-GTP pull-down assay demonstrated that the RhoGAP domain of RhoGAP68F inactivates RhoA but not Rac1 or Cdc42 in HEK293 cells. In addition, expression of RhoGAP68F in NIH3T3 cells suppressed LPA-induced stress fiber formation, which is mediated by RhoA. Finally, neuronal overexpression of RhoGAP68F causes synaptic overgrowth at the larval neuromuscular junction (NMJ). Taken together, these results suggest that RhoGAP68F may play a role in synaptic growth regulation by inactivating RhoA.
Rho 小 GTPases 通过调节肌动蛋白细胞骨架的组装和组织来控制神经元形态发生的多个方面。尽管它们受到 GTPase 激活蛋白 (GAPs) 的负调控，但 RhoGAPs 在神经系统中的作用尚未得到充分研究。在这里，我们描述了一种主要在胚胎中枢神经系统中表达的果蝇 RhoGAP68F 的特征。RNA 原位杂交分析表明，RhoGAP68F 的表达高度局限于胚胎大脑和腹侧神经索。数据库搜索显示，RhoGAP68F 含有一个 N 端 Sec14 结构域和一个 C 端 RhoGAP 结构域。Rho-GTP 下拉测定表明，RhoGAP68F 的 RhoGAP 结构域在 HEK293 细胞中使 RhoA 失活，但不使 Rac1 或 Cdc42 失活。此外，在 NIH3T3 细胞中表达 RhoGAP68F 抑制了由 RhoA 介导的 LPA 诱导的应力纤维形成。最后，神经元过表达 RhoGAP68F 导致幼虫神经肌肉接头 (NMJ) 处的突触过度生长。总之，这些结果表明，RhoGAP68F 可能通过使 RhoA 失活在调节突触生长中发挥作用。
