Abstract
Sleep is a widely conserved behavior, known to influence many cognitive and physiological functions. Studies have implicated microRNAs in the regulation of gene expression changes that control sleep behavior. The Griffith lab screened a library of 143 microRNA sponges using the fruit fly Drosophila melanogaster, in order to find microRNAs involved in sleep regulation (Goodwin et al., 2018). This screen showed miR-190 to be involved in the regulation of sleep. Flies expressing the miR-190-sponge (miR-190-SP) in a pan-neuronal manner showed decreased and fragmented sleep, as well as changes in other sleep parameters. Spatial and temporal mapping of its locus of action demonstrates that miR-190 is required during the pupal stage, in a population of neurons that transcribe both glutamatergic and cholinergic genes, to which we refer to as GluACh cells. Thermogenetic activation of this population of cells by means of dTRPA1 results in a decrease and fragmentation of sleep, phenocopying miR-190 knockdown. At the molecular level, RNA sequencing of both pupal brains and adult heads showed that pan-neuronal expression of miR-190-SP induces an upregulation of multiple genes, among those several cholinergic genes, as well as midline, a T-box transcription factor previously shown to operate as a suppressor of glutamatergic fate. GluACh > mid overexpression phenocopied miR-190 knockdown with animals showing a decrease in total sleep and sleep fragmentation. Additionally, our RNAseq results show downregulation expression of dopaminergic genes upon sleep deprivation of miR-190-SP flies and altered neuronal activity in specific dopaminergic cells. Taken together, our results suggest that miR-190 acts during development in GluACh cells to allow their glutamatergic differentiation, as well as regulating neuronal activity of the sleep/arousal neuronal circuit, ultimately establishing the Drosophila adult sleep behavior.