Extracellular signal-regulated kinase (ERK) activation is required for GP lbα-dependent endothelial cell migration

The GP lb complex can participate in endothelial cell (EC) migration on von Willebrand factor (vWF) or the mixed matrix of vWF and type I collagen (vWF/collagen). In this study, viper venom proteins alboaggregin (albo) A or B blocked GP Ib alpha, and echistatin inhibited alphav beta3 binding. Albo A. B and echistatin inhibited EC migration on vWF and vWF/collagen. Albo B or the anti-GP Ib alpha monoclonal antibody (mAb) Ib1 did not affect the migration of smooth muscle cells or fibroblasts, which lack GP lb. EC also migrate on albo A- or albo B-coated dishes. PD98059. which blocks ERK activation, abolished EC migration on vWF, vWF/collagen, collagen or albo B. Soluble albo A or Ib1 dramatically inhibited ERK activation during EC migration on vWF or albo B. Echistatin inhibited ERK activation on vWF and vitronectin (VN), but not albo B. Thus. in addition to alphav beta3, EC GP Ib alpha initiates ERK activation, and regulates ERK-induced EC migration on vWF.