miR-125b/Ets1 axis regulates transdifferentiation and calcification of vascular smooth muscle cells in a high-phosphate environment

Objectives: Vascular calcification is highly prevalent in patients with chronic kidney disease (CKD) and contributes to increased risk of cardiovascular disease and mortality. Accumulated evidences suggested that vascular smooth muscle cells (VSMCs) to osteoblast-like cells transdifferentiation (VOT) plays a crucial role in promoting vascular calcification. MicroRNAs (miRNAs) are a novel class of small RNAs that negatively regulate gene expression via repression of the target mRNAs. In the present work, we sought to determine the role of miRNAs in VSMCs phenotypic transition and calcification induced by beta-glycerophosphoric acid. Approach and results: Primary cultured rat aortic VSMCs were treated with beta-glycerophosphoric acid for different periods of time. In VSMCs, after beta-glycerophosphoric acid treatment, the expressions of cbf beta 1, osteocalcin and osteopontin were significantly increased and SM-22 beta expression was decreased. ALP activity was induced by beta-glycerophosphoric acid in a time or dose dependent manner. Calcium deposition was detected in VSMCs incubated with calcification media; then, miR-125b expression was detected by real-time RT PCR. miR-125b expression was significantly decreased in VSMCs after incubated with beta-glycerophosphoric acid. Overexpression of miR-125b could inhibit beta-glycerophosphoric acid-induced osteogenic markers expression and calcification of VSMCs whereas knockdown of miR-125b promoted the phenotypic transition of VSMCs and calcification. Moreover, miR-125b targeted Ets1 and regulated its protein expression in VSMCs. Downregulating Ets1 expression by its siRNA inhibited beta-glycerophosphoric acid-induced the VSMCs phenotypic transition and calcification. Conclusion: Our study suggests that down-regulation of miR-125b after beta-glycerophosphoric acid treatment facilitates VSMCs transdifferentiation and calcification through targeting Ets1. (C) 2014 Elsevier Inc. All rights reserved.