Sphingosine 1-phosphate-induced endothelial cell migration requires the expression of EDG-1 and EDG-3 receptors and Rho-dependent activation of alpha(v)beta(3)- and beta(1)-containing integrins

Sphingosine 1-phosphate (SPP), a platelet-derived bioactive lysophospholipi d, is a regulator of angiogenesis. However, molecular mechanisms involved i n SPP-induced angiogenic responses are not fully defined. Here we report th e molecular mechanisms involved in SPP-induced human umbilical vein endothe lial cell (HUVEC) adhesion and migration. SPP-induced HUVEC migration is po tently inhibited by antisense phosphothioate oligonucleotides against EDG-1 as well as EDG-3 receptors, In addition, C3 exotoxin blocked SPP-induced c ell attachment, spreading and migration on fibronectin-, vitronectin- and M atrigel-coated surfaces, suggesting that endothelial differentiation gene r eceptor signaling via the Rho pathway is critical for SPP-induced cell migr ation. Indeed, SPP induced Rho activation in an adherence-independent manne r, whereas Rac activation was dispensible for cell attachment and focal con tact formation. Interestingly, both EDG-1 and -3 receptors were required fo r Rho activation. Since integrins are critical for cell adhesion, migration , and angiogenesis, we examined the effects of blocking antibodies against alpha (v)beta (3), beta (1), or beta (3) integrins. SPP induced Rho-depende nt integrin clustering into focal contact sites, which was essential for ce ll adhesion, spreading and migration. Blockage of alpha (v)beta (3)- or bet a (1)-containing integrins inhibited SPP-induced HUVEC migration. Together our results suggest that endothelial differentiation gene receptor-mediated Rho signaling is required for the activation of integrin alpha (v)beta (3) as well as beta (1)-containing integrins, leading to the formation of init ial focal contacts and endothelial cell migration.