Arc1 : a regulator of triglyceride homeostasis in male Drosophila

Abstract

Achieving metabolic homeostasis is necessary for survival, and many genes are required to control organismal metabolism. A genetic screen in Drosophila larvae identified putative fat storage genes including Arc1 . Arc1 has been shown to act in neurons to regulate larval lipid storage; however, whether Arc1 functions to regulate adult metabolism is unknown. Arc1 ^esm18 males store more fat than controls while both groups eat similar amounts. Arc1 ^esm18 flies express more brummer lipase and less of the glycolytic enzyme triose phosphate isomerase, which may contribute to excess fat observed in these mutants. These results suggest that Arc1 regulates adult Drosophila lipid homeostasis.

Figure 1. Arc1 mutant Drosophila store excess fat

(A) Triglyceride (TAG), glycogen, and free glucose concentrations were measured in approximately 1-2 week old male w ¹¹¹⁸ and Arc1 ^esm18 Drosophila . Bars indicate average macromolecule concentrations normalized by protein concentrations ± standard error (n=16). (B) 1-2 week old male w ¹¹¹⁸ and Arc1 ^esm18 Drosophila were fed 5% sucrose and the amount eaten after 24 hours was measured. Bars represent the average food consumed after 24 hours ± standard error (n=9-12). (C) qPCR was performed for brummer ( bmm ), fatty acid synthase ( FASN1 ), triose phosphate isomerase ( Tpi ), and withered ( whd ) from cDNA generated from RNA samples isolated from 1-2 week old male w ¹¹¹⁸ and Arc1 ^esm18 flies. Expression was normalized by the expression of rp49. Bars indicate the average normalized mRNA expression of each gene ± standard error (n=6). * p < 0.05, ** p < 0.01 as determined by unpaired, two-tailed t-test.