p115RhoGEF activates RhoA to support tight junction maintenance and remodeling

Chumki SA, van den Goor LM, Hall BN, Miller AL. 

Mol Biol Cell. 2022 Dec 1  DOI: 10.1091/mbc.E22-06-0205

An image from the Chumki et al paper on p115RhoGEF’s role in tight junction remodeling was chosen for the cover of Molecular Biology of the Cell. It displays mosaic expression of tight junction protein occluding (orange) along with a probe for active RhoA (magenta) and fluorescently tagged p115RhoGEF antisense morpholino (cyan) in a live Xenopus laevis (African clawed frog) embryo.


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.

Just for fun. . . here is another image that Shahana offered MBoC as a cover option.

credit: MillerLab instagram