Functional analysis of the RhoGEF protein Solo in invasive cell migration

肌动蛋白和微管细胞骨架的动态重塑所需的Rho GT3信号的各种细胞过程，如细胞运动和囊泡运输的内分泌和胞吐。Rho蛋白的调节由鸟嘌呤核苷酸交换因子（GEF）和GTP酶激活蛋白（GAP）协调，其分别开启和关闭GTP酶信号传导。尽管它们在Rho调节中的重要性，但是参与Rho GTd 3活性的空间和时间控制的特定GEF和GAP在很大程度上仍然是难以捉摸的。我们最近确定的RhoGAP蛋白DLC 3调节膜运输的高尔基体和内吞再循环区室的水平，通过当地的RhoA调节。为了鉴定平衡DLC 3 GAP活性的Rho特异性GEF蛋白，我们使用高尔基复合体作为传感器建立了基于图像的高含量显微镜RNAi筛选。我们鉴定了RhoGEF蛋白Solo/Arhgef 40作为Rho调节中的潜在DLC 3对应物。本研究的目的是探讨Solo在调节细胞骨架重塑和膜运输中的细胞功能，并根据我们的初步数据，探讨其对侵袭性细胞迁移的贡献。通过精确定位Solo作用的亚细胞位点，我们进一步旨在揭示其与DLC 3在特定Rho GT3库的空间调控中的分子联系。

The dynamic remodeling of the actin and microtubule cytoskeleton by Rho GTPase signaling is required for various cellular processes such as cell motility and vesicular trafficking in endo- and exocytosis. Regulation of Rho proteins is coordinated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) that turn on and off GTPase signaling, respectively. Despite their importance in Rho regulation, the specific GEFs and GAPs involved in the spatial and temporal control of Rho GTPase activity are still largely elusive. We recently identified the RhoGAP protein DLC3 to regulate membrane trafficking at the level of the Golgi and endocytic recycling compartments by local RhoA regulation. To identify Rho-specific GEF proteins that balance DLC3 GAP activity, we set up an image-based high-content microscopy RNAi screen using the Golgi complex as a sensor. We identified the RhoGEF protein Solo/Arhgef40 as a potential DLC3 counterpart in Rho regulation. The aim of this study is to explore the cellular function of Solo in the regulation of cytoskeletal remodeling and membrane trafficking and, based on our preliminary data, its contribution to invasive cell migration. By pin-pointing the subcellular sites of Solo action, we further aim to unveil its molecular connection with DLC3 in the spatial regulation of specific Rho GTPase pools.