MiR-455-3p inhibits the degenerate process of chondrogenic differentiation through modification of DNA methylation.

The aim of this work was to determine whether miR-455-3p regulates DNA methylation during chondrogenic differentiation of hMSCs. The expression of miR-455-3p and de novo methyltransferase DNMT3A was assessed in micromass culture of hBMSCs, which induced chondrogenic differentiation in vitro, and in E16.5 mice in vivo. A luciferase reporter assay was used to confirm whether miR-455-3p directly targets DNMT3A by interaction with the 3'-UTR. Using an Illumina Infinium Methylation EPIC microarray, genome-wide DNA methylation of hBMSCs with or without overexpressed miR-455-3p was examined for 28 days during induced chondrogenic differentiation. Here, we showed that miR-455-3p was more expressed during the middle stage of hBMSC chondrogenic differentiation, and less expressed in the late stage. DNMT3A was less expressed in the middle stage and more expressed in the late stage, and was also more expressed in the palms of miR-455-3p deletion mice compared to those of wild-type mice. The luciferase reporter assay demonstrated that miR-455-3p directly targets DNMT3A 3'-UTR. miR-455-3p overexpression inhibits the degenerate process during chondrogenic differentiation, while deletion of miR-455-3p in mice accelerated cartilage degeneration. Genome-wide DNA methylation analysis showed miR-455-3p overexpression regulates DNA methylation of cartilage-specific genes. GO analysis revealed PI3K-Akt signaling pathway was most hypomethylated. Our data show that miR-455-3p can regulate hMSC chondrogenic differentiation by affecting DNA methylation. Overexpression of miR-455-3p and DNA methylation inhibitors can thus potentially be utilized to optimize chondrogenic differentiation.