Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48109.
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109.
Mol Biol Cell. 2022 Dec 1;33(14):ar136. doi: 10.1091/mbc.E22-06-0205. Epub 2022 Oct 6.
In vertebrates, epithelial cell-cell junctions must rapidly remodel to maintain barrier function as cells undergo dynamic shape-change events. Consequently, localized leaks sometimes arise within the tight junction (TJ) barrier, which are repaired by short-lived activations of RhoA, called "Rho flares." However, how RhoA is activated at leak sites remains unknown. Here we asked which guanine nucleotide exchange factor (GEF) localizes to TJs to initiate Rho activity at Rho flares. We find that p115RhoGEF locally activates Rho flares at sites of TJ loss. Knockdown of p115RhoGEF leads to diminished Rho flare intensity and impaired TJ remodeling. p115RhoGEF knockdown also decreases junctional active RhoA levels, thus compromising the apical actomyosin array and junctional complex. Furthermore, p115RhoGEF is necessary to promote local leak repair to maintain TJ barrier function. In all, our work demonstrates a central role for p115RhoGEF in activating junctional RhoA to preserve barrier function and direct local TJ remodeling.
在脊椎动物中，上皮细胞-细胞连接必须迅速重塑，以维持屏障功能，因为细胞经历动态形状变化事件。因此，在紧密连接 (TJ) 屏障内有时会出现局部渗漏，这些渗漏通过短暂激活 RhoA 来修复，称为“Rho 爆发”。然而，RhoA 在渗漏部位如何被激活仍然未知。在这里，我们询问哪种鸟嘌呤核苷酸交换因子 (GEF) 定位于 TJ 以在 Rho 爆发时启动 Rho 活性。我们发现 p115RhoGEF 在 TJ 丢失部位局部激活 Rho 爆发。p115RhoGEF 的敲低导致 Rho 爆发强度降低和 TJ 重塑受损。p115RhoGEF 的敲低还降低了连接活性的 RhoA 水平，从而损害了顶端肌动球蛋白阵列和连接复合体。此外，p115RhoGEF 对于促进局部渗漏修复以维持 TJ 屏障功能是必需的。总之，我们的工作表明 p115RhoGEF 在激活连接 RhoA 以维持屏障功能和指导局部 TJ 重塑方面起着核心作用。
