Regulation Of α4 Integrin On Localized Rac Activation In Leading Edge Of Directed Migrating Cells

Rac activation is strongly regulated spacially and temporally in migrating cells, leading to the formation of specific cell protrusion-lamellipodia in leading edge of the cells and generating the pushing force to put the cells forward, but the molecular mechanism of positive regulation of localized Rac activation remains unclear. This project proposes that the phosphorylation of the intracellular α4 integrin inhibits the interaction of α4 with paxillin, thus the signaling pathway paxillin-GIT1-PIX-PAK would be formed, leading to localized Rac activation in leading edge of the migrating cells. First, we verified the activation of hFN on Rac protein. Second, We proved the existence of the Signal molecule complexes Previously by western blot which showed that the interactions accurately exist between the cytoskeleton proteins GIT1 and paxillin or PIX respectively. Third, we confirmed that these interactions between GIT1 and paxillin or PIX emerged in leading edge of cells. Forth, we used FRET single molecule probe to detect the activation of Rac.