Endothelin-1 Signaling in Vascular Physiology and Pathophysiology

The discovery of endothelin (ET) in 1988 has led to considerable effort to unravel its implication in health and disease and the mechanisms evoked by ET. ET-1 and related signaling aberrancies are believed to be implicated in the pathogenesis of diverse cardiovascular diseases, such as hypertension, atherosclerosis, hypertrophy and diabetes. The endothelin system consists of three potent vasoconstrictive isopeptides, ET-1, ET-2 and ET-3, signaling through two G protein coupled receptors, ETA and ETB, which are linked to multiple signaling pathways. Activated signaling transduction pathways include the modulation of the adenylyl cyclase/cAMP pathway through stimulatory (Gs) and inhibitory (Gi) G proteins, activation of the phosphoinositide pathway through the activation of proteins Gq/11, generation of oxidative stress, growth factor receptor-related mitogenic events, such as the activation of phosphatidylinositol-3 kinase pathway, phosphoinositide pathway and activation of the mitogen-activated protein (MAP) kinase cascade. The levels of ETA and ETB receptors as well as the signaling pathways activated by these receptors are altered in several cardiovascular diseases including hypertension, hypertrophy, atherosclerosis, diabetes, etc. In this review, we provide an overview of the signaling events modulated by ET-1 in vascular smooth muscle cells in both physiological and pathological conditions.