AKAP5 and Caveolin-1 organize opposing nanodomains that regulate smooth muscle contraction and blood pressure

Abstract

TRPV4 ion channels in vascular smooth muscle cells (SMCs) are crucial regulators of blood pressure, and their functional effects are differentially shaped by their signaling partners. However, the mechanisms by which TRPV4 channels are compartmentalized into distinct signaling nanodomains with opposite impacts on blood pressure remain unclear. Here, we identify the scaffolding proteins that compartmentalize TRPV4 channels into discrete nanometer-scale signaling domains at the SMC plasma membrane and define how these nanodomains produce opposing effects on vasoconstriction and blood pressure. We show that AKAP5 anchors a nanodomain linking 1-adrenergic receptors, protein kinase C and TRPV4 channels, thereby driving sympathetic vasoconstriction and blood pressure elevation. In contrast, caveolin-1 promotes a mechanosensitive nanodomain comprising Piezo1, TRPV4, and BK channels that mediates vasodilation and a decrease in blood pressure. In hypertension, AKAP5-dependent constrictor nanodomains are hyperactive, whereas caveolin-1-based dilator nanodomains are hypoactive, shifting the balance toward pathological vasoconstriction. These findings reveal fundamental mechanisms that organize smooth muscle TRPV4 channels into spatially and functionally distinct nanodomains regulating blood pressure and show how disruption of this organization contributes to blood pressure elevation in hypertension.