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Abstract：
Recent findings indicate that Solo, a RhoGEF, is involved in cellular mechanical stress responses. However, the mechanism of actin cytoskeletal remodeling via Solo remains unclear. Therefore, this study aimed to identify Solo-interacting proteins using the BioID, a proximal-dependent labeling method, and elucidate the molecular mechanisms of function of Solo. We identified PDZ-RhoGEF (PRG) as a Solo-interacting protein. PRG colocalized with Solo in the basal area of cells, depending on Solo localization, and enhanced actin polymerization at the Solo accumulation sites. Additionally, Solo and PRG interaction was necessary for actin cytoskeletal remodeling. Furthermore, the purified Solo itself had little or negligible GEF activity, even its GEF-inactive mutant directly activated the GEF activity of PRG through interaction. Moreover, overexpression of the Solo and PRG binding domains, respectively, had a dominant-negative effect on actin polymerization and actin stress fiber formation in response to substrate stiffness. Therefore, Solo restricts the localization of PRG and regulates actin cytoskeletal remodeling in synergy with PRG in response to the surrounding mechanical environment.
摘要：
最近的研究结果表明，索洛，aRhoGEF，参与细胞机械应激反应。然而,通过Solo进行肌动蛋白细胞骨架重塑的机制尚不清楚。因此,这项研究旨在使用BioID鉴定Solo相互作用蛋白，一种近端依赖标记方法，并阐明了Solo功能的分子机制。我们将PDZ-RhoGEF(PRG)鉴定为Solo相互作用蛋白。PRG与Solo共同定位在细胞的基底区域，根据Solo本地化，并增强了Solo积累位点的肌动蛋白聚合。此外,Solo和PRG相互作用是肌动蛋白细胞骨架重塑所必需的。此外，纯化的Solo本身几乎没有或可以忽略不计的GEF活动，甚至GEF非活性突变体也通过相互作用直接激活了PRG的GEF活性。此外，Solo和PRG结合结构域的过表达，分别,响应于底物刚度，对肌动蛋白聚合和肌动蛋白应力纤维形成具有显性负效应。因此,Solo限制了PRG的定位，并与PRG协同调节肌动蛋白细胞骨架重塑，以响应周围的机械环境。
