The Role and Mechanism of α-Klotho in the Calcification of Rat Aortic Vascular Smooth Muscle Cells

Objective. To investigate the role and possible mechanism of alpha-Klotho in the calcification and the osteogenic transition of cultured VSMCs. Methods. VSMCs were cultured in vitro and divided into 5 groups, each using a different medium: (1) control; (2) beta-GP; (3) beta-GP + Klotho; (4) beta-GP + LiCl; (5) beta-GP + Klotho + LiCl. Calcium deposits were visualized using Alizarin Red S staining. The calcium concentrations were determined by the o-cresolphthalein complexone method. BMP2, Runx2 and beta-catenin levels were estimated by western blotting, and the level of alpha-SMA was determined by using immunofluorescence at day 12. Results. beta-GP induced an increase in the expression of BMP2, Runx2, and beta-catenin. The calcium content increased, and the expression of alpha-SMA decreased. Alizarin Red S staining was positive under the high phosphorus conditions. BMP2, Runx2, and beta-catenin levels and the calcium content decreased when the cells were cultured with rmKlotho; however, the levels of each were upregulated after treatment with the LiCl. Conclusions. Klotho can ameliorate the calcification and osteogenic transition of VSMCs induced by beta-GP. The mechanism of Klotho in preventing calcification in VSMCs may be partially mediated by the inhibition of the Wnt/beta-catenin signaling pathway.