Sexually dimorphic microRNA miR-190 regulates lifespan in male Drosophila.

microRNAs are short noncoding RNAs that buffer fluctuations in gene expression in a myriad of physiological conditions. Here, we carried out a screen to identify the role of microRNAs in the maintenance of age-dependent neuronal functions in adult Drosophila. We report that miR-190 acts in the neurons to regulate lifespan, neuronal maintanence and age-related locomotor activity specifically in male flies. miR-190, a highly conserved microRNA, shows higher expression levels in male flies. Our data suggest that miR-190 functions by regulating target genes that are involved in maintaining neuronal activity and lifespan in male flies.

Nutrient dependent miR-184 aids in the survival of Drosophila larvae during low food conditions.

Nutrition is one of the critical factors known to regulate the development and growth of organisms. Lack of nutrients affects the proper functioning and survival of organisms. However, fluctuation of the levels of nutrients is quite common in a natural environment, and organisms have evolved various molecular and physiological means by which they can survive such conditions. microRNAs are short non-coding RNAs that play significant biological functions, primarily by acting as post-transcriptional buffers of noisy gene expression. Recent studies show that miR-184, a conserved microRNA, is expressed at higher levels in low nutrition conditions. Our experiments show that miR-184 mutants showed enhanced lethality when raised in low nutrient food conditions. Here, we demonstrate the role of miR-184, a microRNA regulated by nutritional status, also helps in the survival of the larvae to adulthood in low food conditions.

Insulin signalling elicits hunger-induced feeding in Drosophila.

Insulin, a highly conserved peptide hormone, links nutrient availability to metabolism and growth in animals. In fed states insulin levels remain high and in animals that are food deprived insulin signalling drops. Here, we report that in Drosophila, feeding elicited by short periods of starvation is dependent on insulin signalling. The activity of insulin signalling pathway in the abdominal fatbody aids in feeding during short periods of starvation. A feedback regulatory signalling that involves cells that express the Drosophila hunger hormone short-neuropeptide-F (sNPF) and insulin-producing cells sustain the orexigenic function of insulin. Furthermore, the orexigenic phase of insulin activity aids in the efficient management of nutrient stores and survival of flies during starvation.