Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität Göttingen, 37077 Göttingen, Germany.
Mech Dev. 2010 Jul-Aug;127(7-8):371-84. doi: 10.1016/j.mod.2010.01.001. Epub 2010 Jan 11.
Essential for proper function of small GTPases of the Rho family, which control many aspects of cytoskeletal and membrane dynamics, is their temporal and spatial control by activating GDP exchange factors (GEFs) and deactivating GTPase-activating-proteins (GAPs). The regulatory mechanisms controlling these factors are not well understood, especially during development, when the organization and behaviour of cells change in a stage dependent manner. During Drosophila cellularization Rho signalling and RhoGEF2 are involved in furrow canal formation and the organization of actin and myosin. Here we analyze, how RhoGEF2 is localized at the sites of membrane invagination. We show that the PDZ domain is necessary for localization and function of RhoGEF2 and identify Slam as a factor that is necessary for RhoGEF2 localization. We also demonstrate that Slam can recruit RhoGEF2 to ectopic sites. Furthermore we find that the PDZ domain of RhoGEF2 can form a complex with Slam invivo and that Slam transcripts and protein colocalize at the furrow canal and in basal particles. Based on these findings, we propose that accumulation of slam mRNA and protein at the presumptive invagination site provides a spatial and temporal trigger for RhoGEF2-Rho1 signalling.
小 GTP 酶 Rho 家族的正确功能对于其控制细胞骨架和膜动态的许多方面至关重要，这依赖于其通过激活 GDP 交换因子 (GEFs) 和失活 GTP 酶激活蛋白 (GAPs) 来实现的时间和空间控制。这些因子的调节机制还没有被很好地理解，尤其是在发育过程中，细胞的组织和行为以依赖于阶段的方式发生变化。在果蝇细胞化过程中，Rho 信号和 RhoGEF2 参与了沟道的形成以及肌动蛋白和肌球蛋白的组织。在这里，我们分析了 RhoGEF2 如何在膜内陷部位定位。我们表明 PDZ 结构域对于 RhoGEF2 的定位和功能是必要的，并确定 Slam 是 RhoGEF2 定位所必需的一个因子。我们还证明了 Slam 可以将 RhoGEF2 募集到异位部位。此外，我们发现 RhoGEF2 的 PDZ 结构域可以在体内与 Slam 形成复合物，并且 Slam 转录本和蛋白质在沟道和基底颗粒处共定位。基于这些发现，我们提出在假定的内陷部位积累 slam mRNA 和蛋白质为 RhoGEF2-Rho1 信号提供了时空触发。
