Uncovering the K IR Mechanosignaling Complex in Vascular Smooth Muscle

Abstract

Inwardly rectifying potassium (KIR) channels contribute to the setting of membrane potential in vascular smooth muscle (VSM). Recent work has demonstrated their regulation by pressure, although the underlying mechanism remains unclear. This study sought to identify key signaling components that enable this mechanosensitive response in rat cerebral arterial myocytes. Initial patch clamp electrophysiology confirmed that pressure, initiated by a hyposmotic challenge, suppresses KIR currents in isolated cells. Actin disruption with Cytochalasin D and Latrunculin A abolished this response, implying participation of the cytoskeleton. Interactions between ion channels and actin filaments are often facilitated through structural protein intermediates. In this context, we examined syntrophin and caveolin-1 scaffolding proteins as they have each been previously found to interact with KIR channels. Peptide blockade of caveolin-1 prevented KIR suppression after hyposmotic challenge in subsequent patch clamp experiments. Immunohistochemistry highlighted expression of both syntrophin and caveolin-1 in VSM, while proximity ligation assay revealed their co-localization with KIR2.2 subunits. These findings provide evidence that KIR mechanosensitivity involves interactions with the cytoskeleton which are likely mediated by scaffolding proteins.