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PLoS Genet. 2015 Jun 4;11(6):e1005245. doi: 10.1371/journal.pgen.1005245. eCollection 2015 Jun.

Multiple In Vivo Biological Processes Are Mediated by Functionally Redundant Activities of Drosophila mir-279 and mir-996.

Author information

1
Sloan-Kettering Institute, Department of Developmental Biology, New York, New York, United States of America; Neuroscience Program, Weill Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America.
2
Sloan-Kettering Institute, Department of Developmental Biology, New York, New York, United States of America; Molecular Biology Program, Weill Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America.
3
Sloan-Kettering Institute, Department of Developmental Biology, New York, New York, United States of America.

Abstract

While most miRNA knockouts exhibit only subtle defects, a handful of miRNAs are profoundly required for development or physiology. A particularly compelling locus is Drosophila mir-279, which was reported as essential to restrict the emergence of CO2-sensing neurons, to maintain circadian rhythm, and to regulate ovarian border cells. The mir-996 locus is located near mir-279 and bears a similar seed, but they otherwise have distinct, conserved, non-seed sequences, suggesting their evolutionary maintenance for separate functions. We generated single and double deletion mutants of the mir-279 and mir-996 hairpins, and cursory analysis suggested that miR-996 was dispensable. However, discrepancies in the strength of individual mir-279 deletion alleles led us to uncover that all extant mir-279 mutants are deficient for mature miR-996, even though they retain its genomic locus. We therefore engineered a panel of genomic rescue transgenes into the double deletion background, allowing a pure assessment of miR-279 and miR-996 requirements. Surprisingly, detailed analyses of viability, olfactory neuron specification, and circadian rhythm indicate that miR-279 is completely dispensable. Instead, an endogenous supply of either mir-279 or mir-996 suffices for normal development and behavior. Sensor tests of nine key miR-279/996 targets showed their similar regulatory capacities, although transgenic gain-of-function experiments indicate partially distinct activities of these miRNAs that may underlie that co-maintenance in genomes. Altogether, we elucidate the unexpected genetics of this critical miRNA operon, and provide a foundation for their further study. More importantly, these studies demonstrate that multiple, vital, loss-of-function phenotypes can be rescued by endogenous expression of divergent seed family members, highlighting the importance of this miRNA region for in vivo function.

PMID:
26042831
PMCID:
PMC4456407
DOI:
10.1371/journal.pgen.1005245
[Indexed for MEDLINE]
Free PMC Article

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