Abstract
Canonical primary microRNA (miRNA) transcripts and mirtrons are proposed to transit distinct nuclear pathways en route to generating mature ∼22 nucleotide regulatory RNAs. We generated a null allele of Drosophila pasha, which encodes a double-stranded RNA-binding protein partner of the RNase III enzyme Drosha. Analysis of this mutant yielded stringent evidence that Pasha is essential for the biogenesis of canonical miRNAs but is dispensable for the processing and function of mirtron-derived regulatory RNAs. The pasha mutant also provided a unique tool to study the developmental requirements for Drosophila miRNAs. While pasha adult somatic clones are similar in many respects to those of dicer-1 clones, pasha mutant larvae revealed an unexpected requirement for the miRNA pathway in imaginal disc growth. These data suggest limitations to somatic clonal analysis of miRNA pathway components.
SUPPLEMENTAL MATERIAL
Supplemental material for this article may be found at http://mcb.asm.org/ .
ACKNOWLEDGMENTS
We thank Richard Carthew, Stephen Cohen, Hugo Bellen, Qinghua Liu, and the Bloomington Stock Center for providing Drosophila stocks used in this study. Herbert Jäckle and Reinhard Lührmann provided logistical support to generate the knockout. Dae-Hwan Kim generated some of the recombinant strains.
This study was supported by the Howard Hughes Medical Institute (T.T.) and grants from the V Foundation for Cancer Research, the Sidney Kimmel Cancer Foundation, the Alfred Bressler Scholars Fund, and the U.S. National Institutes of Health (R01-GM083300) to E.C.L.