METTL3 regulates skeletal muscle specific miRNAs at both transcriptional and post-transcriptional levels

Biochem Biophys Res Commun. 2021 May 7;552:52-58. doi: 10.1016/j.bbrc.2021.03.035. Epub 2021 Mar 17.

Abstract

METTL3 increasing the mature miRNA levels via N6-Methyladenosine (m6A) modification of primary miRNA (pri-miRNA) transcripts has emerged as an important post-transcriptional regulation of miRNA biogenesis. Our previous studies and others have showed that muscle specific miRNAs are essential for skeletal muscle differentiation. Whether these miRNAs are also regulated by METTL3 is still unclear. Here, we found that m6A motifs were present around most of these miRNAs, which were indeed m6A modified as confirmed by m6A-modified RNA immunoprecipitation (m6A RIP). However, we surprisingly found that these muscle specific miRNAs were repressed instead of increased by METTL3 in C2C12 in vitro differentiation and mouse skeletal muscle regeneration after injury in vivo model. To elucidate the underlined mechanism, we performed reporter assays in 293T cells and validated METTL3 increasing these miRNAs at post-transcriptional level as expected. Furthermore, in myogenic C2C12 cells, we found that METTL3 not only repressed the expression of myogenic transcription factors (TFs) which can enhance the muscle specific miRNAs, but also increased the expression of epigenetic regulators which can repress these miRNAs. Thus, METTL3 could repress the muscle specific miRNAs at transcriptional level indirectly. Taken together, our results demonstrated that skeletal muscle specific miRNAs were repressed by METTL3 and such repression is likely synthesized transcriptional and post-transcriptional regulations.

Keywords: HDAC; MEF2C; METTL3; Skeletal muscle differentiation; m6A; miRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation / genetics
  • Cell Line
  • HEK293 Cells
  • Humans
  • Male
  • Methyltransferases / genetics*
  • Methyltransferases / metabolism
  • Mice, Inbred C57BL
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / metabolism*
  • Myoblasts / cytology
  • Myoblasts / metabolism
  • RNA Processing, Post-Transcriptional / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcriptional Activation / genetics*

Substances

  • MicroRNAs
  • Methyltransferases
  • Mettl3 protein, mouse