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

Autor: David Jee, Hong Duan, Kailiang Sun, Eric C. Lai, Luis F. de Navas
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: PLoS Genetics, Vol 11, Iss 6, p e1005245 (2015)
PLoS Genetics
ISSN: 1553-7404
1553-7390
Popis: 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.
Author Summary Amongst the small number of miRNA knockouts that exhibit substantially overt phenotypes, mutants of Drosophila mir-279 are notable. Previous studies have uncovered its essential requirements in a range of developmental and behavioral assays. Surprisingly, we find that the phenotypes attributed to mir-279 deletions depend on the unanticipated loss of expression of the downstream locus mir-996, whose genomic locus is retained in extant mir-279 mutants. These miRNAs share their seed regions but are divergent elsewhere in the mature sequences. We use precise genetic engineering to show that a single endogenous copy of either mir-279 or mir-996 can fully rescue viability, olfactory neuron, and circadian rhythm defects of double deletion animals. These data and genetic reagents set a new foundation for developmental and behavioral studies of this critical miRNA locus. More generally, these data demonstrate that multiple loss-of-function phenotypes can be rescued by endogenous expression of divergent seed family members, highlighting the importance and potentially sufficiency of this region for in vivo function.
Databáze: OpenAIRE
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