Primary microRNA transcripts are processed co-transcriptionally.

Journal article

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.

Authors: Morlando, M; Ballarino, M; Gromak, N; Pagano, F; Bozzoni, I

• Publication status: Published
• Journal: Nat Struct Mol Biol
• Volume: 15
• Issue: 9
• Pages: 902-909
• Publication date: 2008-08-31
• DOI: 10.1038/nsmb.1475
• ISSN: 1545-9985
• Language: English