RhoGDI2 positively regulates the Rho GTPases activation in response to the β2 outside-in signaling in T cells adhesion and migration on ICAM-1.

Cytoskeletal reorganization driven by Rho GTPases plays a crucial role in the migration of T cells, which are key regulators of immunity. The molecular mechanisms that control actin cytoskeleton remodeling during T cell movement have only partially been clarified as the function of many modulators has not been evaluated in these cells. Here, we report a new function of RhoGDI2 by showing that this protein positively regulates Rho GTPase activation during T cell adhesion and migration. RhoGDI2 knockdown significantly reduced T cell adhesion and migration. Furthermore, RhoGDI2 knockdown decreased the activation of Rac1 and Cdc42, 2 members of Rho GTPases, and the remodeling of the actin cytoskeleton. Upon P-selectin glycoprotein ligand-1 engagement, RhoGDI2 was phosphorylated at Y24 and Y153 by kinases related to β2 integrin outside-in signaling, Src, c-Abl, and Syk, resulting in the accumulation of RhoGDI2 at the cell membrane. Subsequent phosphorylation of S31 induced the opening of RhoGDI2 and the release of Rho GTPases, whereas phosphorylation of Y153 might promote the activation of Rho GTPases by recruiting Vav1. Moreover, the disruption of lipid rafts with methyl-β-cyclodextrin blocked the interaction between integrins and RhoGDI2, reducing the level of phosphorylated RhoGDI2 and the activation of downstream Rho GTPases. Based on these observations, RhoGDI2 is a target of intergrin outside-in signaling that activates Rho GTPases during T cell adhesion and migration, and RhoGDI2-mediated signal transduction is based on the lipid rafts integrity.