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

N6-methyladenosine marks primary microRNAs for processing.

Author information

1
Laboratory of Systems Cancer Biology, Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.

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.

PMID:
25799998
PMCID:
PMC4475635
DOI:
10.1038/nature14281
[Indexed for MEDLINE]
Free PMC Article

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