IRE-1 and HSP-4 contribute to energy homeostasis via fasting-induced lipases in C. elegans

Cell Metab. 2009 May;9(5):440-8. doi: 10.1016/j.cmet.2009.04.004.

Abstract

The endoplasmic reticulum (ER) is an organelle associated with lipid metabolism. However, the involvement of the ER in nutritional status-dependent energy homeostasis is largely unknown. We demonstrate that IRE-1, an ER protein known to be involved in the unfolded protein response, and HSP-4, an ER chaperone, regulate expression of the novel fasting-induced lipases FIL-1 and FIL-2, which induce fat granule hydrolysis upon fasting in C. elegans. RNAi and ectopic expression experiments demonstrated that FIL-1 and FIL-2 are both necessary and sufficient for fasting-induced fat granule breakdown. Failure of ire-1 and hsp-4 mutant animals to hydrolyze fat granules during starvation impaired their motility, which was rescued by glucose supplementation, implicating the importance of ire-1/hsp-4-dependent lipolysis for energy supply from stored fat during fasting. These data suggest that the ER-resident proteins IRE-1 and HSP-4 are key nutritional sensors that modulate expression of inducible lipases to maintain whole-body energy homeostasis in C. elegans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans / enzymology*
  • Caenorhabditis elegans Proteins / metabolism*
  • Endoplasmic Reticulum / metabolism
  • Energy Metabolism
  • Fasting
  • Heat-Shock Proteins / metabolism*
  • Lipase / classification
  • Lipase / metabolism*
  • Phylogeny
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Interference

Substances

  • Caenorhabditis elegans Proteins
  • Heat-Shock Proteins
  • Hsp-4 protein, C elegans
  • Protein-Serine-Threonine Kinases
  • IRE-1 protein, C elegans
  • Lipase

Associated data

  • GEO/GSE15656