Fluid shear stress induces synthesis and nuclear localization of c-fos in cultured human endothelial cells.

Quiescent cultured primary human umbilical vein endothelial cells were exposed to low levels (4 dynes/cm2) or arterial levels (25 dynes/cm2) of steady laminar shear stress for one hour. Intracellular c-fos protein was measured by immunocytochemistry and quantitative fluorescence video microscopy. The nuclear-localized c-fos protein level was 5.4 +/- 2.0 fold higher (p < 0.01) in the cells exposed to arterial levels of shear stress as compared to the cells maintained in stationary culture. In contrast, the cells exposed to low levels of shear stress showed diffuse but slightly elevated levels of c-fos (2.4 +/- 0.73 times higher than control; p < 0.01) without preferential nuclear localization. The protein kinase C inhibitor, H7 (10 microM) significantly attenuated the induction of c-fos by 50% in cells exposed to arterial shear stress for 1 hour.