Low Chloride-Regulated ClC-5 Contributes to Arterial Smooth Muscle Cell Proliferation and Cerebrovascular Remodeling

Low serum chloride (Cl^-) level is considered an independent predictor of cardiovascular mortality associated with chronic hypertension. However, the underlying mechanisms are unknown. ClC-5, a member of the Cl^- channel family, is sensitive to changes in intracellular and extracellular Cl^- concentration and conducts outwardly rectifying Cl^- currents. The aims of this study were to determine if ClC-5 is regulated by low extracellular Cl^-, clarify its putative roles in hypertension-induced cerebrovascular remodeling, and elucidate the associated underlying mechanisms.

Whole-cell patch technique, intracellular Cl^- concentration measurements, flow cytometry, Western blot, Clcn5 knockdown (Clcn5^-/y), and adenovirus-mediated ClC-5 overexpression mice, 2-kidney, 2-clip, and angiotensin II infusion-induced hypertensive models were used.

We found that low extracellular Cl^- evoked a ClC-5-dependent Cl^- current that was abolished by ClC-5 depletion in basilar artery smooth muscle cells (BASMCs). ClC-5 was upregulated in the arterial tissues of rats and patients with hypertension. Low Cl^--induced current and ClC-5 protein expression positively correlated with basilar artery remodeling during hypertension. ClC-5 knockdown ameliorated hypertension-induced cerebrovascular remodeling and smooth muscle cell proliferation, whereas ClC-5 overexpression mice exhibited the opposite phenotype. ClC-5-dependent Cl^- efflux induced by low extracellular Cl^- activated WNK1 (lysine-deficient protein kinase 1) which, in turn, activated AKT (protein kinase B), and culminated in BASMC proliferation and vascular remodeling.

ClC-5 mediates low extracellular Cl-induced Cl^- currents in BASMCs and regulates hypertension-induced cerebrovascular remodeling by promoting BASMC proliferation via the WNK1/AKT signaling pathway.