Tetraspanin-enriched membrane domains regulate vascular leakage by altering membrane cholesterol accessibility to balance antagonistic GTPases

Abstract

Tetraspanins affect metastasis, stemness and angiogenesis, but their roles in inflammation remain to be further clarified. Here we show that endothelial ablation of tetraspanin Cd82 markedly reduces vascular inflammation by mitigating endothelial leakage. Mechanistically, by limiting the anchorages of Cdc42 activator FARP1 and RhoA inhibitor Rnd3 to the plasma membrane (PM), CD82 confines Cdc42 but maintains RhoA activity in endothelial cells, to facilitate endothelium activation. These signaling regulatory effects depend on the ability of CD82 to coalesce and retain accessible cholesterol (AC) at the PM, whereas simvastatin overturns CD82 effects by lowering AC. CD82 supports non-vesicular transfer of AC to the PM through oxysterol-binding protein-related proteins (ORPs). Thus, CD82 and AC promote vascular leakage, whereas statin and ORP inhibitor restrain vascular leakage by decreasing AC. These findings reveal an unconventional anti-inflammation role and mechanism for statin and conceptualize tetraspanin-mediated, AC-mediated and cholesterol transfer-mediated balancing of antagonistic GTPase signaling pathways as regulatory mechanisms for vascular leakage.