TITLE

Primary microRNA transcripts are processed co-transcriptionally

AUTHOR(S)
Morlando, Mariangela; Ballarino, Monica; Gromak, Natalia; Pagano, Francesca; Bozzoni, Irene; Proudfoot, Nick J.
PUB. DATE
September 2008
SOURCE
Nature Structural & Molecular Biology;Sep2008, Vol. 15 Issue 9, p902
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
microRNAs (miRNAs) are generated from long primary (pri-) RNA polymerase II (Pol II)–derived transcripts by two RNase III processing reactions: Drosha cleavage of nuclear pri-miRNAs and Dicer cleavage of cytoplasmic pre-miRNAs. Here we show that Drosha cleavage occurs during transcription acting on both independently transcribed and intron-encoded miRNAs. We also show that both 5′-3′ and 3′-5′ exonucleases associate with the sites where co-transcriptional Drosha cleavage occurs, promoting intron degradation before splicing. We finally demonstrate that miRNAs can also derive from 3` flanking transcripts of Pol II genes. Our results demonstrate that multiple miRNA-containing transcripts are co-transcriptionally cleaved during their synthesis and suggest that exonucleolytic degradation from Drosha cleavage sites in pre-mRNAs may influence the splicing and maturation of numerous mRNAs.
ACCESSION #
34139472

 

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