The m6A reader YTHDF2 protects vascular smooth muscle cells against the osteogenic differentiation through targeting Runx2.

Abstract

Vascular calcification (VC) is an important pathological development progress in chronic kidney disease (CKD) and may increase mortality but lacks effective treatments. N6-methyladenosine (m6A) has been verified to be the most prevalent internal chemical RNA modification in mammalian mRNAs. The M6A-modified mRNA degradation process is mediated by the reader YTHDF2 in an m6A-dependent manner. Nevertheless, the exact role and molecular mechanism of YTHDF2 in VC remain unclear. This study aimed to investigate the potential role of YTHDF2 in the osteogenic differentiation of vascular smooth muscle cells (VSMCs). It was found that YTHDF2 was markedly downregulated in both in vivo and in vitro calcified models. Functionally, YTHDF2 plays a protective role in VC. The overexpression of YTHDF2 inhibited the transdifferentiation of VSMCs from a contractile to an osteogenic phenotype, thus decreasing the expression of mineralization regulatory proteins and calcium deposition. Conversely, YTHDF2 deficiency aggravated this process. At the mechanistic level, YTHDF2 suppressed osteogenic transdifferentiation of VSMCs by regulating the Runt-related transcription factor 2 (Runx2). RNA immunoprecipitation-qPCR (RIP-qPCR) confirmed the binding of YTHDF2 to Runx2, and luciferase reporter assays confirmed the presence of the m6A site in Runx2. In addition, an actinomycin D assay showed that the half-life of Runx2 mRNA was dramatically shortened in VSMCs overexpressing YTHDF2. These results suggest that YTHDF2 directly binds to the m6A modification site of Runx2 to mediate the mRNA degradation that prevents VC by inhibiting the osteogenic development of VSMCs. Therefore, YTHDF2 can be considered a potential therapeutic target for managing VC.