Contrasting roles of different endoglin forms in atherosclerosis

Endoglin (also known as CD105 or TGF-β type III receptor) is a co-receptor involved in TGF-β signaling. In atherosclerosis, TGF-β signaling is crucial in regulating disease progression owing to its anti-inflammatory effects as well as its inhibitory effects on smooth muscle cell proliferation and migration. Endoglin is a regulator of TGF-β signaling, but its role in atherosclerosis has yet to be defined. This review focuses on the roles of the various forms of endoglin in atherosclerosis. The expression of the two isoforms of endoglin (long-form and short-form) is increased in atherosclerotic lesions, and the expression of the soluble forms of endoglin is upregulated in sera of patients with hypercholesterolemia and atherosclerosis. Interestingly, long-form endoglin shows an atheroprotective effect via the induction of eNOS expression, while short-form and soluble endoglin enhance atherogenesis by inhibiting eNOS expression and TGF-β signaling. This review summarizes evidence suggesting that the different forms of endoglin have distinct roles in atherosclerosis.