ClC-2 knockdown prevents cerebrovascular remodeling via inhibition of the Wnt/β-catenin signaling pathway.

BACKGROUND:Mishandling of intracellular chloride (Cl^-) concentration ([Cl^-]_i) in cerebrovascular smooth muscle cells is implicated in several pathological processes, including hyperplasia and remodeling. We investigated the effects of ClC-2-mediated Cl^- efflux on the proliferation of human brain vascular smooth muscle cells (HBVSMCs) induced by angiotensin II (AngII). METHODS:Cell proliferation and motility were determined using the CCK-8, bromodeoxyuridine staining, wound healing and invasion assays. ClC-2, PCNA, Ki67, survivin and cyclin D1 expression, and β-catenin and GSK-3β phosphorylation were examined using western blotting. Histological analyses were performed using hematoxylin and eosin staining and α-SMA staining. RESULTS:Our results showed that AngII-induced HBVSMC proliferation was accompanied by a decrease in [Cl^-]_i and an increase in ClC-2 expression. Inhibition of ClC-2 by siRNA prevented AngII from inducing the efflux of Cl^-. AngII-induced HBVSMC proliferation, migration and invasion were significantly attenuated by ClC-2 downregulation. The inhibitory effects of ClC-2 knockout on HBVSMC proliferation and motility were associated with inactivation of the Wnt/β-catenin signaling pathway, as evidenced by inhibition of β-catenin phosphorylation and nuclear translocation, and decrease of GSK-3β phosphorylation and survivin and cyclin D1 expression. Recombinant Wnt3a treatment markedly reversed the effect of ClC-2 knockdown on HBVSMC viability. An in vivo study revealed that knockdown of ClC-2 with shRNA adenovirus ameliorated basilar artery remodeling by inhibiting Wnt/β-catenin signaling in AngII-treated mice. CONCLUSION:This study demonstrates that blocking ClC-2-mediated Cl^- efflux inhibits AngII-induced cerebrovascular smooth muscle cell proliferation and migration by inhibiting the Wnt/β-catenin pathway. Our data indicate that downregulation of ClC-2 may be a viable strategy in the prevention of hyperplasia and remodeling of cerebrovascular smooth muscle cells.

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