Abstract
Leukocyte infiltration is a hallmark of the atherosclerotic lesion. These cells are captured by cellular adhesion molecules (CAMs), including vascular cell adhesion molecule‐1 (VCAM‐1), intercellular adhesion molecule‐1 (ICAM‐1), platelet‐endothelial cell adhesion molecule (PECAM), and E‐selectin, on endothelial cells (EC). We examined the role of the actin cytoskeleton in tumor necrosis factor‐alpha (TNF‐α)‐induced translocation of CAMs to the cell surface. Human aortic EC were grown on 96‐well plates and an ELISA was used to assess surface expression of the CAMs. TNF‐α increased VCAM‐1, ICAM‐1, and E‐selectin by 4 h but had no affect on the expression of PECAM. A functioning actin cytoskeleton was important for VCAM‐1 and ICAM‐1 expression as both cytochalasin D, an actin filament disruptor, and jasplakinolide, an actin filament stabilizer, attenuated the expression of these CAMs. These compounds were ineffective in altering E‐selectin surface expression. Myosin light chains are phosphorylated in response to TNF‐α and this appears to be regulated by Rho kinase instead of myosin light chain kinase. However, the Rho kinase inhibitor, Y27632, had no affect on TNF‐α‐induced CAM expression. ML‐7, a myosin light chain kinase inhibitor, had a modest inhibitory effect on the translocation of VCAM‐1 but not on ICAM‐1 or E‐selectin. These data suggest that the surface expression of VCAM‐1 and ICAM‐1 is dependent on cycling of the actin cytoskeleton. Nevertheless, modulation of actin filaments via myosin light chain phosphorylation is not necessary. The regulation of E‐selectin surface expression differs from that of the other CAMs. © 2004 Wiley‐Liss, Inc.