The role and mechanism of klotho in the calcification of rat aortic vascular smooth muscle cells

Abstract

Objective. To investigate the role and possible mechanism of -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) β-GP; (3) β-GP + Klotho; (4) β-GP + LiCl; (5) β-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 β-catenin levels were estimated by western blotting, and the level of -SMA was determined by using immunofluorescence at day 12. Results. β-GP induced an increase in the expression of BMP2, Runx2, and β-catenin. The calcium content increased, and the expression of -SMA decreased. Alizarin Red S staining was positive under the high phosphorus conditions. BMP2, Runx2, and β-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 β-GP. The mechanism of Klotho in preventing calcification in VSMCs may be partially mediated by the inhibition of the Wnt/β-catenin signaling pathway.