Régulation du métabolisme des lipides par les récepteurs nucléaires orphelins

Translated title of the contribution: Regulation of lipid metabolism by the orphan nuclear receptors

J. M A Lobaccaro, J. J. Repa, T. T. Lu, F. Caira, J. Henry-Berger, D. H. Volle, D. J. Mangelsdorf

Research output: Contribution to journalReview article

18 Scopus citations

Abstract

Lipids (cholesterol and fatty acids) are essential nutriments and have a major impact on gene expression. Hence cholesterol intracellular concentration is precisely controlled by some complex mechanisms involving transcriptional regulations. The excess of cholesterol in cells is converted into oxysterols. These cholesterol metabolites are important signalisation molecules that modulate several transcription factors involved in cholesterol homeostasis. Schematically, regulation of cholesterol homeostasis is achieved by three different but complementary pathways: 1) endogeneous biosynthesis, which corresponds to the de novo synthesis of cholesterol and is controlled by sterol response element binding proteins (SREBPs); 2) the transport, intracellular absorption and esterification of the cholesterol; 3) the metabolic conversion into bile acids and steroid hormones. These three pathways are closely linked, however we will schematically detail the role of the orphan nuclear receptors on the modulation of these three levels of regulation. Phenotype analyses of knock-out or transgenic mice pointed out the respective role of the « enterohepatic » orphan nuclear receptors LXRα LXRβ, FXR, LRH-1, the nuclear receptor PPARα, and their heterodimeric partner RXR, as well as the peculiar receptor SHP. Complex feed-backs have thus been demonstrated. These transciptional regulations have several targets: the P450 cytochromes involved in the bile acid synthesis Cyp7a1 and Cyp8b1; the intestinal bile acid binding protein IBABP; the cholesteryl ester transfert protein CETP and phospholipid transfert protein PLTP, both involved in the HDL catabolism; the ABC cholesterol transporters ABCG1/ABC8 and ABCAI/ABCI. At last it seems that polyunsaturated fatty acids could activate LXRα transcription through its activation by PPARα. In the near future, the identification and study of new target genes by transcriptomic or proteomic analyses will allow a better understanding of lipid homeostasis in physiological as well as pathophysiological conditions.

Translated title of the contributionRegulation of lipid metabolism by the orphan nuclear receptors
Original languageFrench
Pages (from-to)239-247
Number of pages9
JournalAnnales d'Endocrinologie
Volume62
Issue number3
StatePublished - Jul 26 2001

Keywords

  • Bile acids
  • Cholesterol homeostasis
  • Cytochromes P450
  • LXR
  • Lipid metabolism
  • Membrane transporters of cholesterol ABC
  • Orphan nuclear receptors

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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  • Cite this

    Lobaccaro, J. M. A., Repa, J. J., Lu, T. T., Caira, F., Henry-Berger, J., Volle, D. H., & Mangelsdorf, D. J. (2001). Régulation du métabolisme des lipides par les récepteurs nucléaires orphelins. Annales d'Endocrinologie, 62(3), 239-247.