Roles of focal adhesion kinase and paxillin in focal adhesion dynamics of living endothelial cells

Abstract

Focal adhesion kinase (FAK) is a signaling protein that can activate the adaptor protein paxillin, which is also localized at focal adhesions (FAs) and associated with integrins, to influence the cytoskeleton and membrane protrusions, thereby regulating FA dynamics and cell motility. In living ECs transfected with GFP‐FAK and DsRed‐paxillin, concurrent monitoring of the intracellular dynamics of FAK and paxillin by time‐lapse video recording and dual‐color fluorescence imaging showed the co‐localization of FAK and paxillin at FAs. The ratio of the fluorescence intensities (FI) of FAK/paxillin was determined during assembly/disassembly of FAs. The FAK/paxillin FI ratio of FA sites was higher in the cytoplasm than in the perinuclear region. This ratio in the cytoplasm increased as the dynamics of FA sites became active, especially at the leading edge of the migrating EC. Our findings show the roles of FAK and paxillin in the assembly/disassembly of FAs and in cell adhesion. We conclude that both molecules play important roles in modulating the FA dynamics and cellular signaling during cell migration. This work was supported by NHLBI Research Grants HL‐080518 and HL‐085159 (S.C.).