Seto, E. S. | Search bioRxiv

bioRxiv2023

RNAi-based screen for cuticle pigmentation in Drosophila melanogaster reveals novel regulators of brain dopamine

The dopaminergic system has been extensively studied for its role in behavior and neurological diseases. Despite this, we still know little about how dopamine levels are regulated in vivo. To identify regulators of dopamine, we utilized Drosophila melanogaster cuticle pigmentation as a readout, where dopamine is used as a precursor to melanin. We started by measuring dopamine from known pigmentation mutants (e.g. tan, ebony, black) and then performed an RNAi-based screen to identify new regulators. We found 153 hits, which were enriched for developmental signaling pathways and mitochondria-associated proteins. From 35 prioritized candidates, 11 had an effect on head dopamine levels. Effects on brain dopamine were mild even when the rate-limiting synthesis enzyme Tyrosine hydroxylase (TH) was knocked down, suggesting changes in dopamine levels are tightly regulated in the nervous system. We pursued two of our hits that reduced brain dopamine levels, clueless and mask. Further examination suggests that mask regulates transcription of TH and affects dopamine-dependent sleep patterns. In summary, by studying genes that affect cuticle pigmentation, we were able to identify genes that affect dopamine metabolism as well as a novel regulator of behavior.

neuroscience↗

bioRxiv2019

A genetic screen for genes that impact peroxisomes in Drosophila identifies candidate genes for human disease

Peroxisomes are sub-cellular organelles that are essential for proper function of eukaryotic cells. In addition to being the sites of a variety of oxidative reactions, they are crucial regulators of lipid metabolism. Peroxisome loss or dysfunction leads to multisystem diseases in humans that strongly affects the nervous system. In order to uncover previously unidentified genes and mechanisms that impact peroxisomes, we conducted a genetic screen on a collection of lethal mutations on the X chromosome in Drosophila. Using the number, size and morphology of GFP tagged peroxisomes as a readout, we screened for mutations that altered the number and morphology of peroxisomes based on clonal analysis and confocal microscopy. From this screen, we identified 18 genes that cause increases in peroxisome number or altered morphology when mutated. We examined the human homologs of these genes and found that they are involved in a diverse array of cellular processes. Interestingly, the human homologs from the X-chromosome collection are under selective constraint in human populations and are good candidate genes particularly for dominant genetic disease. This in vivo screening approach for peroxisome defects allows identification of novel genes that impact peroxisomes in vivo in a multicellular organism and is a valuable platform to discover genes potentially involved in dominant disease that could affect peroxisomes.

genetics↗