Drosophila Melanogaster Acetyl-CoA-carboxylase Sustains a Fatty Acid-Dependent Remote Signal to Waterproof the Respiratory System

PLoS Genet. 2012;8(8):e1002925. doi: 10.1371/journal.pgen.1002925. Epub 2012 Aug 30.

Abstract

Fatty acid (FA) metabolism plays a central role in body homeostasis and related diseases. Thus, FA metabolic enzymes are attractive targets for drug therapy. Mouse studies on Acetyl-coenzymeA-carboxylase (ACC), the rate-limiting enzyme for FA synthesis, have highlighted its homeostatic role in liver and adipose tissue. We took advantage of the powerful genetics of Drosophila melanogaster to investigate the role of the unique Drosophila ACC homologue in the fat body and the oenocytes. The fat body accomplishes hepatic and storage functions, whereas the oenocytes are proposed to produce the cuticular lipids and to contribute to the hepatic function. RNA-interfering disruption of ACC in the fat body does not affect viability but does result in a dramatic reduction in triglyceride storage and a concurrent increase in glycogen accumulation. These metabolic perturbations further highlight the role of triglyceride and glycogen storage in controlling circulatory sugar levels, thereby validating Drosophila as a relevant model to explore the tissue-specific function of FA metabolic enzymes. In contrast, ACC disruption in the oenocytes through RNA-interference or tissue-targeted mutation induces lethality, as does oenocyte ablation. Surprisingly, this lethality is associated with a failure in the watertightness of the spiracles-the organs controlling the entry of air into the trachea. At the cellular level, we have observed that, in defective spiracles, lipids fail to transfer from the spiracular gland to the point of air entry. This phenotype is caused by disrupted synthesis of a putative very-long-chain-FA (VLCFA) within the oenocytes, which ultimately results in a lethal anoxic issue. Preventing liquid entry into respiratory systems is a universal issue for air-breathing animals. Here, we have shown that, in Drosophila, this process is controlled by a putative VLCFA produced within the oenocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyl-CoA Carboxylase* / genetics
  • Acetyl-CoA Carboxylase* / metabolism
  • Animals
  • Carbohydrate Metabolism
  • Drosophila melanogaster* / genetics
  • Drosophila melanogaster* / metabolism
  • Fat Body / cytology
  • Fat Body / metabolism
  • Fatty Acids / genetics
  • Fatty Acids / metabolism*
  • Glycogen / metabolism
  • Hypoxia / genetics
  • Hypoxia / metabolism
  • Lipid Metabolism / genetics*
  • RNA Interference
  • Respiratory System / metabolism*
  • Triglycerides / genetics
  • Triglycerides / metabolism
  • Water / metabolism

Substances

  • Fatty Acids
  • Triglycerides
  • Water
  • Glycogen
  • Acetyl-CoA Carboxylase

Grant support

This work was supported by Agence Nationale de la Recherche, ANR-05-BLAN-0228-01, Fondation pour la Recherche Medicale, FRM INE20041102449, and Association pour la Recherche sur le Cancer, ARC Equipement. LN was a recipient of a fellowship from FRM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.