Tlr4-mutant mice are resistant to acute alcohol-induced sterol-regulatory element binding protein activation and hepatic lipid accumulation

Sci Rep. 2016 Sep 15:6:33513. doi: 10.1038/srep33513.

Abstract

Previous studies demonstrated that acute alcohol intoxication caused hepatic lipid accumulation. The present study showed that acute alcohol intoxication caused hepatic lipid accumulation in Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic sterol-regulatory element binding protein (SREBP)-1, a transcription factor regulating fatty acid and triglyceride (TG) synthesis, was activated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic Fas, Acc, Scd-1 and Dgat-2, the key genes for fatty acid and TG synthesis, were up-regulated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Additional experiment showed that hepatic MyD88 was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic NF-κB was activated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Moreover, hepatic GSH content was reduced and hepatic MDA level was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic CYP2E1 was elevated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Hepatic p67phox and gp91phox, two NADPH oxidase subunits, were up-regulated in alcohol-treated Tlr4-wild-type mice but not in Tlr4-mutant mice. Alpha-phenyl-N-t-butylnitrone (PBN), a free radical spin-trapping agent, protected against alcohol-induced hepatic SREBP-1 activation and hepatic lipid accumulation. In conclusion, Tlr4-mutant mice are resistant to acute alcohol-induced hepatic SREBP-1 activation and hepatic lipid accumulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcoholic Intoxication / metabolism
  • Animals
  • Cyclic N-Oxides / pharmacology
  • Cytochrome P-450 CYP2E1 / metabolism
  • Enzyme Activation / drug effects
  • Ethanol / toxicity*
  • Fatty Acids / biosynthesis
  • Insulin / metabolism
  • Lipid Metabolism*
  • Liver / metabolism*
  • Mice, Mutant Strains
  • Myeloid Differentiation Factor 88 / metabolism
  • NADPH Oxidases / metabolism
  • NF-kappa B / metabolism
  • Oxidative Stress / drug effects
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein Binding / drug effects
  • Protein Subunits / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Signal Transduction / drug effects
  • Sterol Regulatory Element Binding Protein 1 / metabolism*
  • Toll-Like Receptor 4 / metabolism*
  • Triglycerides / metabolism
  • Up-Regulation / genetics

Substances

  • Cyclic N-Oxides
  • Fatty Acids
  • Insulin
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • Protein Subunits
  • Sterol Regulatory Element Binding Protein 1
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Triglycerides
  • phenyl-N-tert-butylnitrone
  • Ethanol
  • Cytochrome P-450 CYP2E1
  • NADPH Oxidases
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt