Drosophila E78A nuclear receptor regulates intestinal dietary triacylglyceride uptake and systemic lipid levels
Here we show that the Drosophila nuclear receptor E78A regulates transcription in adult animals facilitating dietary lipid uptake. E78A mutant adults are viable with normal developmental timing, locomotor activity, female fecundity, but have significantly reduced stored triglycerides. This reduction in whole body triglyceride stores appears to originate from the midgut, using neutral lipid stainings we determined lipid levels in the midgut were greatly reduced. Upon examining our RNA-seq analysis we found that a gastric lipase, CG17192, is transcriptionally coordinated by E78A. CG17192 is expressed in an adult, intestinal specific fashion within control flies, and has a human ortholog. Through dietary supplementation and genetic testing we determined that the whole body hypolipidemia seen within E78A mutants is dependent on CG17192 expression within the intestine. Restoration of this lipase in the intestine of mutant flies is sufficient to restore normal lipid levels. Our data support the model that E78A contributes to a transcriptional regulation of the gastric lipase, CG17192, thus directing dietary triglyceride uptake in the adult fly. Overall design: Comparison of mRNA levels in control and E78A mutant animals. n=4-5 replicates per genotype