N6-methyladenosine marks primary microRNAs for processing

Nature. 2015 Mar 26;519(7544):482-5. doi: 10.1038/nature14281. Epub 2015 Mar 18.

Abstract

The first step in the biogenesis of microRNAs is the processing of primary microRNAs (pri-miRNAs) by the microprocessor complex, composed of the RNA-binding protein DGCR8 and the type III RNase DROSHA. This initial event requires recognition of the junction between the stem and the flanking single-stranded RNA of the pri-miRNA hairpin by DGCR8 followed by recruitment of DROSHA, which cleaves the RNA duplex to yield the pre-miRNA product. While the mechanisms underlying pri-miRNA processing have been determined, the mechanism by which DGCR8 recognizes and binds pri-miRNAs, as opposed to other secondary structures present in transcripts, is not understood. Here we find in mammalian cells that methyltransferase-like 3 (METTL3) methylates pri-miRNAs, marking them for recognition and processing by DGCR8. Consistent with this, METTL3 depletion reduced the binding of DGCR8 to pri-miRNAs and resulted in the global reduction of mature miRNAs and concomitant accumulation of unprocessed pri-miRNAs. In vitro processing reactions confirmed the sufficiency of the N(6)-methyladenosine (m(6)A) mark in promoting pri-miRNA processing. Finally, gain-of-function experiments revealed that METTL3 is sufficient to enhance miRNA maturation in a global and non-cell-type-specific manner. Our findings reveal that the m(6)A mark acts as a key post-transcriptional modification that promotes the initiation of miRNA biogenesis.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenosine / metabolism
  • Base Sequence
  • Cell Line
  • Gene Expression Regulation
  • Humans
  • Methylation
  • Methyltransferases / deficiency
  • Methyltransferases / metabolism
  • MicroRNAs / chemistry*
  • MicroRNAs / metabolism*
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • RNA Processing, Post-Transcriptional*
  • RNA-Binding Proteins / metabolism
  • Substrate Specificity

Substances

  • DGCR8 protein, human
  • MicroRNAs
  • RNA-Binding Proteins
  • N6-methyladenosine (m6A)
  • Methyltransferases
  • METTL3 protein, human
  • Adenosine

Associated data

  • GEO/GSE60213