title: Multiple In Vivo Biological Processes Are Mediated by Functionally Redundant Activities of Drosophila mir-279 and mir-996.
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.
authors.affiliation: 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.
authors.forename: Kailiang
authors.initials: K
authors.lastname: Sun
authors.affiliation: 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.
authors.forename: David
authors.initials: D
authors.lastname: Jee
authors.affiliation: Sloan-Kettering Institute, Department of Developmental Biology, New York, New York, United States of America.
authors.forename: Luis F
authors.initials: LF
authors.lastname: de Navas
authors.affiliation: Sloan-Kettering Institute, Department of Developmental Biology, New York, New York, United States of America.
authors.forename: Hong
authors.initials: H
authors.lastname: Duan
authors.affiliation: Sloan-Kettering Institute, Department of Developmental Biology, New York, New York, United States of America.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Lai
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics; D004330:Drosophila / Q000235:genetics / Q000378:metabolism; D049750:Genome, Insect; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D055495:Neurogenesis / Q000235:genetics; D010641:Phenotype
chemical_list: C568310:MIRN279 microRNA, Drosophila; C000608177:MIRN996 microRNA, Drosophila; D035683:MicroRNAs