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Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534 Nature 2015 ; 519 (7544): 482-5 Nephropedia Template TP
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N6-methyl-adenosine (m6A) marks primary microRNAs for processing #MMPMID25799998
Alarcón CR; Lee H; Goodarzi H; Halberg N; Tavazoie SF
Nature 2015[Mar]; 519 (7544): 482-5 PMID25799998show ga
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 ribonuclease type III DROSHA1?4. This initial event requires the 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 product5. While the mechanisms underlying pri-miRNA processing have been elucidated, the mechanism by which DGCR8 recognizes and binds pri-miRNAs as opposed to other secondary structures present in transcripts is not understood. We find 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 m6A 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 m6A mark acts as a key post-transcriptional modification that promotes the initiation of miRNA biogenesis.