p38 mitogen activated protein kinase regulates endothelial VCAM-1 expression at the post-transcriptional level.

The cytokine tumor necrosis factor (TNF) alpha was found to stimulate the p38 mitogen activated protein (MAP) kinase signalling cascade in human umbilical vein endothelial cells. TNFalpha increased the activity of the p38 substrate MAP kinase-activated-protein (MAPKAP) kinase 2 and the subsequent phosphorylation of the small heat shock protein Hsp27 about two to three fold. This stimulation was blocked almost completely by the specific p38 MAP kinase inhibitor SB203580. This inhibitor also suppressed the TNFalpha-induced surface expression of the endothelial adhesion molecule vascular cell adhesion molecule (VCAM)-1. In contrast, inhibition of p38 MAP kinase had no effect on the stimulated surface expression of the intercellular cell adhesion molecule (ICAM)-1. VCAM-1 mRNA accumulation induced by TNFalpha was not affected by SB203580, suggesting that the p38 MAP kinase signalling cascade regulates the endothelial expression of VCAM-1 at the post-transcriptional level.