Environmental pollutants directly affect the liver X receptor alpha activity: Kinetic and thermodynamic characterization of binding

J Steroid Biochem Mol Biol. 2015 Aug;152:1-7. doi: 10.1016/j.jsbmb.2015.04.011. Epub 2015 Apr 11.

Abstract

Liver X receptor is a ligand-activated transcription factor, which is mainly involved in cholesterol homeostasis, bile acid and triglycerides metabolism, and, as recently discovered, in the glucose metabolism by direct regulation of liver glucokinase. Its modulation by exogenous factors, such as drugs, industrial by-products, and chemicals is documented. Owing to the abundance of these synthetic molecules in the environment, and to the established target role of this receptor, a number of representative compounds of phthalate, organophosphate and fibrate classes were tested as ligands/modulators of human liver X receptor, using an integrated approach, combining an in silico molecular docking technique with an optical SPR biosensor binding study. The compounds of interest were predicted and proved to target the oxysterols-binding site of human LXRα with measurable binding kinetic constants and with affinities ranging between 4.3 × 10(-7) and 4.3 × 10(-8)M. Additionally, non-cytotoxic concentration of these chemicals induced relevant changes in the LXRα gene expression levels and other target genes (SREBP-1c and LGK) in human liver hepatocellular carcinoma cell line (HepG2), as demonstrated by q-RT-PCR.

Keywords: Binding study; Cell culture; Liver X receptor; Molecular docking; Plasticizers; q-RT-PCR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cell Line, Tumor
  • Environmental Pollutants / metabolism*
  • Environmental Pollutants / pharmacology
  • Fibric Acids / metabolism*
  • Fibric Acids / pharmacology
  • Hep G2 Cells
  • Humans
  • Liver X Receptors
  • Molecular Docking Simulation
  • Organophosphates / metabolism*
  • Organophosphates / pharmacology
  • Orphan Nuclear Receptors / biosynthesis
  • Orphan Nuclear Receptors / genetics
  • Orphan Nuclear Receptors / metabolism*
  • Phthalic Acids / metabolism*
  • Phthalic Acids / pharmacology
  • Protein Binding
  • RNA, Messenger / biosynthesis
  • Receptors, Steroid / metabolism
  • Sterol Regulatory Element Binding Protein 1 / biosynthesis
  • Sterol Regulatory Element Binding Protein 1 / genetics
  • Sterol Regulatory Element Binding Protein 1 / metabolism

Substances

  • Environmental Pollutants
  • Fibric Acids
  • Liver X Receptors
  • NR1H3 protein, human
  • Organophosphates
  • Orphan Nuclear Receptors
  • Phthalic Acids
  • RNA, Messenger
  • Receptors, Steroid
  • Sterol Regulatory Element Binding Protein 1
  • oxysterol binding protein
  • phthalic acid