Phosphatidylinositol-3 kinase dependent MAP kinase activation via p21ras in endothelial cells exposed to cyclic strain.

Hemodynamic forces play a key role in the modulation of the morphology and function of the endothelium by activating several kinases. We have previously shown that cyclic strain, a repetitive mechanical stretch, induces activation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), members of the mitogen activated protein (MAP) kinase family. In order to investigate the upstream pathway of strain-induced ERK1/2 activation, we examined p21ras activation by cyclic strain and the effect of wortmannin and LY294002, phosphatidylinositol-3 kinase (PI 3-kinase) inhibitors on ERK1/2 phosphorylation. Cyclic strain induced a transient and rapid activation of p21ras at 1 min after strain. Wortmannin inhibited strain-induced ERK1/2 activation by 56.3 and 86.3 %, respectively. LY294002 inhibited ERK1 activation completely and ERK2 activation by 42.9%. These results suggest a possible involvement of p21ras and PI 3-kinase in the signal transduction pathway leading to the strain-induced ERK1/2 activation. Copyright 1999 Academic Press.