Coordinate regulation of lipid metabolism by novel nuclear receptor partnerships

PLoS Genet. 2012;8(4):e1002645. doi: 10.1371/journal.pgen.1002645. Epub 2012 Apr 12.

Abstract

Mammalian nuclear receptors broadly influence metabolic fitness and serve as popular targets for developing drugs to treat cardiovascular disease, obesity, and diabetes. However, the molecular mechanisms and regulatory pathways that govern lipid metabolism remain poorly understood. We previously found that the Caenorhabditis elegans nuclear hormone receptor NHR-49 regulates multiple genes in the fatty acid beta-oxidation and desaturation pathways. Here, we identify additional NHR-49 targets that include sphingolipid processing and lipid remodeling genes. We show that NHR-49 regulates distinct subsets of its target genes by partnering with at least two other distinct nuclear receptors. Gene expression profiles suggest that NHR-49 partners with NHR-66 to regulate sphingolipid and lipid remodeling genes and with NHR-80 to regulate genes involved in fatty acid desaturation. In addition, although we did not detect a direct physical interaction between NHR-49 and NHR-13, we demonstrate that NHR-13 also regulates genes involved in the desaturase pathway. Consistent with this, gene knockouts of these receptors display a host of phenotypes that reflect their gene expression profile. Our data suggest that NHR-80 and NHR-13's modulation of NHR-49 regulated fatty acid desaturase genes contribute to the shortened lifespan phenotype of nhr-49 deletion mutant animals. In addition, we observed that nhr-49 animals had significantly altered mitochondrial morphology and function, and that distinct aspects of this phenotype can be ascribed to defects in NHR-66- and NHR-80-mediated activities. Identification of NHR-49's binding partners facilitates a fine-scale dissection of its myriad regulatory roles in C. elegans. Our findings also provide further insights into the functions of the mammalian lipid-sensing nuclear receptors HNF4α and PPARα.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Caenorhabditis elegans* / genetics
  • Caenorhabditis elegans* / metabolism
  • Fatty Acid Desaturases / metabolism
  • Gene Expression Profiling
  • Gene Knockout Techniques
  • Gene Regulatory Networks
  • Humans
  • Lipid Metabolism*
  • Mitochondria / metabolism
  • Protein Binding
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Sequence Deletion
  • Signal Transduction
  • Sphingolipids / metabolism

Substances

  • Caenorhabditis elegans Proteins
  • NHR-49 protein, C elegans
  • NHR-80 protein, C elegans
  • Receptors, Cytoplasmic and Nuclear
  • Sphingolipids
  • Fatty Acid Desaturases