Richhariya, S. | Search bioRxiv

bioRxiv2021

Dopamine and GPCR-mediated modulation of DN1 clock neurons gates the circadian timing of sleep

The metronome-like circadian regulation of sleep timing must still adapt to an uncertain environment. Recent studies in Drosophila indicate that neuromodulation not only plays a key role in clock neuron synchronization but also affects interactions between the clock network and brain sleep centers. We show here that the targets of neuromodulators, G-Protein Coupled Receptors (GPCRs), are highly enriched in the fly brain circadian clock network. Single cell sequencing indicates that they are not only differentially expressed but also define clock neuron identity. We generated a comprehensive guide library to mutagenize individual GPCRs in specific neurons and verified the strategy with a targeted sequencing approach. Combined with a behavioral screen, the mutagenesis strategy revealed a novel role of dopamine in sleep regulation by identifying two dopamine receptors and a clock neuron subpopulation that gate the timing of sleep.

neuroscience↗

bioRxiv2020

IP3/Ca2+ signals regulate larval to pupal transition under nutrient stress through the H3K36 methyltransferase dSET2

Persistent loss of dietary protein usually signals a shutdown of key metabolic pathways. In Drosophila larvae, that have crossed "critical weight" and can pupariate to form viable adults, such a metabolic shut-down would needlessly lead to death. IP3/Ca2+ signals in certain interneurons (vGlutVGN6341) allow Drosophila larvae to pupariate on a protein-deficient diet by partially circumventing this shutdown through upregulation of neuropeptide signaling and the expression of ecdysone synthesis genes. Here we show that IP3/Ca2+ signals in vGlutVGN6341 neurons drive expression of dSET2, a Drosophila Histone 3 Lysine 36 methyltransferase. Further, dSET2 expression is required for larvae to pupariate in the absence of dietary protein. IP3/Ca2+ signal-driven dSET2 expression upregulates key Ca2+ signaling genes through a novel positive feedback loop. Transcriptomic studies coupled with analysis of existing ChIP-seq datasets identified genes from larval and pupal stages, that normally exhibit robust H3K36 trimethyl marks on their gene bodies and concomitantly undergo stronger downregulation by knockdown of either an intracellular Ca2+ release channel the IP3R or dSET2. IP3/Ca2+ signals thus regulate gene expression through dSET2 mediated H3K36 marks on select neuronal genes for the larval to pupal transition.

developmental biology↗