Canonical and alternate functions of the microRNA biogenesis machinery.
The canonical microRNA (miRNA) biogenesis pathway requires two RNaseIII enzymes: Drosha and Dicer. To understand their functions in mammals in vivo, we engineered mice with germline or tissue-specific inactivation of the genes encoding these two proteins. Changes in proteomic and transcriptional profiles that were shared in Dicer- and Drosha-deficient mice confirmed the requirement for both enzymes in canonical miRNA biogenesis. However, deficiency in Drosha or Dicer did not always result in identical phenotypes, suggesting additional functions. We found that, in early-stage thymocytes, Drosha recognizes and directly cleaves many protein-coding messenger RNAs (mRNAs) with secondary stem-loop structures. In addition, we identified a subset of miRNAs generated by a Dicer-dependent but Drosha-independent mechanism. These were distinct from previously described mirtrons. Thus, in mammalian cells, Dicer is required for the biogenesis of multiple classes of miRNAs. Together, these findings extend the range of function of RNaseIII enzymes beyond canonical miRNA biogenesis, and help explain the nonoverlapping phenotypes caused by Drosha and Dicer deficiency.
Chong
Mark M W
MM
Molecular Pathogenesis Program, Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York 10016, USA. chong@wehi.edu.au
Zhang
Guoan
G
Cheloufi
Sihem
S
Neubert
Thomas A
TA
Hannon
Gregory J
GJ
Littman
Dan R
DR
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D053487:DEAD-box RNA Helicases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D055029:Inverted Repeat Sequences; D051379:Mice; D035683:MicroRNAs / Q000096:biosynthesis*; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D043244:Ribonuclease III / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
D035683:MicroRNAs; D012333:RNA, Messenger; D004722:Endoribonucleases; C509781:Dicer1 protein, mouse; C513400:Drosha protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases