Regulation of Lipid Metabolism in Drosophila

Until recently it was believed that insulin was the main regulator of lipogenic gene expression. However, it has been shown that nutrients themselves play a role in the regulation of these genes and that many lipogenic genes contain carbohydrate responsive elements (ChRE) within their promoters. These response elements were used to identify ChRE‐binding factors that mediate lipogenic gene expression, including carbohydrate responsive element binding protein, ChREBP. We examined the role of the Drosophila homolog of ChREBP, Mio, in the regulation of fatty acid synthesis, triglyceride storage and lipogenic gene expression. Using the Gal 4/ UAS system, we created transgenic flies that expressed a MioRNAi knockdown construct. We assayed triglyceride levels in larvae lacking Mio in their fat bodies and used RT‐PCR to examine Fatty Acid Synthase (dFAS) and Acetyl‐CoA Carboxylase (dACC) expression. We observed a decrease in larval triglyceride levels in 2 independent transgenic lines. Consistent with a decrease in triglycerides, we also observed a decrease in dFAS and dACC expression. We concluded that Mio is necessary for regulating triglyceride storage as well as lipogenic gene expression.