Membrane fluidity regulates high shear stress-induced FAK activation at different subcellular compartments

Focal adhesion kinase(FAK)plays a vital role in mediating the adaptability of tumor cells under mechanical stimuli.Previous studies revealed that FAK can locate to different cell compartments,and its regulation is highly dependent on its subcellular localization.However,the local FAK activities and its regulation mechanism in different cell compartments of tumor cells in response to fluid shear stress are still unclear.In this study,5 dyn/cm^(2) and 20 dyn/cm^(2) of shear stress was applied to HeLa cells for 30 min.The activities of FAK targeting different subcellular compartments(lipids rafts,non-rafts,focal adhesions and cytoplasm)were investigated with fluorescence resonance energy transfer(FRET)technology.Results showed that the activity of FAK in response to high shear stress at focal adhesion sites was lower than that of other three areas,while no difference among four areas was observed in response to low shear stress.Furthermore,high shear stress-induced distinct FAK activation at different compartments was inhibited by decreasing membrane fluidity,but Src inhibition prevented high shear stress-induced FAK activation only in the cytoplasm.This study revealed the spatiotemporal characteristics of FAK under the different magnitude of shear stress,which provides a deeper understanding of mechanotransduction in tumor cells.