METTL14 mediates m ⁶a modification on osteogenic proliferation and differentiation of bone marrow mesenchymal stem cells by regulating the processing of pri-miR-873

Abstract

N ⁶-methyl-adenosine (m ⁶a) is involved in the occurrence and development of various diseases such as autogenic immune disease and tumors. Methyltransferases regulate primary (pri)-microRNA (miRNA/miR) processing by mediating m6a modifications, consequently affecting pathological processes including immune-related diseases by regulating both innate and adaptive immune cells. However, the roles of m ⁶a on the biological functions of bone marrow mesenchymal stem cells (BMSCs) remain to be elucidated. The relative expression levels of methyltransferase-like 14 (METTL14) and other methyltransferases, demethylases, and miR-873 in bone samples from patients with osteoporosis and from normal individuals were measured by reverse transcription-quantitative PCR. Cell Counting Kit-8 assay was used to examine the proliferation of BMSCs. Co-immunoprecipitation (Co-IP) was used to investigate the binding of METTL14 to DiGeorge syndrome critical region 8 (DGCR8). RNA immunoprecipitation (RIP) was used to examine the binding of METTL14 to pri-miR-873. METTL14 and m ⁶a modifications were highly detected in patients with osteoporosis compared with the controls. Co-IP results indicated that silencing of METTL14 reduced METTL14 and m ⁶a modification levels in BMSCs. Downregulation of METTL14 significantly promoted the proliferation of BMSCs. RIP results suggested that METTL14/m ⁶a methylation modification promoted the processing of pri-miR-873 by binding to DGCR8 in BMSCs. Furthermore, overexpression of miR-873 inhibited the proliferation of BMSCs. The results also showed that miR-873 mimics significantly inhibited the proliferation in small interfering (si)-METTL14 transfected BMSCs; however, miR-873 inhibitors markedly promoted the proliferation of si-METTL14 transfected BMSCs. METTL14 and m ⁶a modifications were upregulated in osteoporosis samples. METTL14 promoted the processing of pri-miR-873 into mature miR-873 by regulating m ⁶a modification. Furthermore, overexpression of miR-873 significantly inhibited the proliferation of BMSCs. Therefore, the METTL14/m ⁶a/miR-873 axis may be a potential target for the treatment of osteoporosis.