miR615-3p inhibited FBLN1 and osteogenic differentiation of umbilical cord mesenchymal stem cells by associated with YTHDF2 in a m6A-miRNA interaction manner.

To investigate the role and mechanism of FBLN1 in the osteogenic differentiation and bone regeneration by using umbilical cord mesenchymal stem cells (WJCMSCs). We found that FBLN1 promoted osteogenic differentiation of WJCMSCs and WJCMSC-mediated bone regeneration. It was showed that there was an m6A methylation site in 3'UTR of FBLN1 mRNA, and the mutation of the m6A site enhanced the stability of FBLN1 mRNA, subsequently fostering the FBLN1 enhanced osteogenic differentiation of WJCMSCs. YTHDF2 was identified as capable of recognizing and binding to the m6A site, consequently inducing FBLN1 instability and repressed the osteogenic differentiation of WJCMSCs. Meanwhile, miR-615-3p negatively regulated FBLN1 by binding FBLN1 3'UTR and inhibited the osteogenic differentiation of WJCMSCs and WJCMSC-mediated bone regeneration. Then, we discovered miR-615-3p was found to regulate the functions of FBLN1 facilitated by YTHDF2 through an m6A-miRNA regulation mechanism. We demonstrated that FBLN1 is critical for regulating the osteogenic differentiation potentials of WJCMSCs and have identified that miR615-3p mediated the decay of FBLN1 mRNA which facilitated by m6A reading protein YTHDF2. This provided a novel m6A-miRNA epigenetic regulatory pattern for MSC regulation and bone regeneration.