Wound-induced migration of rat hepatic stellate cells is modulated by endothelin-1 through rho-kinase-mediated alterations in the acto-myosin cytoskeleton

Although migration of stellate cells during hepatic injury is essential for wound-healing and fibrosis of the liver, the extracellular and intracellul ar signals that regulate stellate cell migration are incompletely understoo d, In this study we tested the hypothesis that wound-induced migration of s tellate cells is modulated by endothelin-1 (ET-1) through rhokinase-mediate d alterations in the acto-myosin cytoskeleton. To address this hypothesis, a method was established for direct visualization of wound-induced migratio n of culture-activated stellate cells with subcellular resolution, Migratio n in response to wounding was characterized by (1) plasma membrane ruffling and protrusion into the wound, (2) lamellipodia formation at the leading e dge, (3) focal adhesion and stress fiber assembly, and (4) myosin reorganiz ation. Exogenous ET-1 accelerated wound-induced migration of stellate cells , but did not alter wound-induced proliferation. Experiments using ET-1 ant agonists in the absence of exogenous ET-1 showed that wound-induced migrati on was also stimulated by endogenous ET-1, Selective inhibition of rho-asso ciated kinase decelerated migration in response to wounding. Moreover, inhi bition of rho-associated kinase was distinguished by abrogation of focal ad hesion formation, stress fiber assembly, and myosin reorganization. This st udy shows that rho-kinase-dependent alterations in the acto-myosin cytoskel eton contribute to wound-induced stellate cell migration, which is accelera ted by both exogenous and endogenous ET-1, Consequently, these results prov ide important new evidence suggesting that, migration of stellate cells is modulated by paracrine and autocrine ET-1 stimulation via the action of rho -kinase on the acto-myosin cytoskeleton.