Identification of 5′ AMP-activated Kinase as a Target of Reactive Aldehydes during Chronic Ingestion of High Concentrations of Ethanol

• Published in: The Journal of biological chemistry Vol. 289; no. 22; pp. 15449 - 15462
• Main Authors: Shearn, Colin T., Backos, Donald S., Orlicky, David J., Smathers-McCullough, Rebecca L., Petersen, Dennis R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.05.2014; American Society for Biochemistry and Molecular Biology
• Subjects: Alcohol; Aldehydes - metabolism; Aldehydes - pharmacology; AMP-activated Kinase (AMPK); AMP-Activated Protein Kinases - chemistry; AMP-Activated Protein Kinases - metabolism; Animals; Central Nervous System Depressants - pharmacology; Cysteine Proteinase Inhibitors - pharmacology; Disease Models, Animal; Ethanol - pharmacology; Fatty Liver - enzymology; Hep G2 Cells; Humans; Lipid Peroxidation; Lipid Peroxidation - drug effects; Lipid Peroxidation - physiology; Lipids; Liver; Liver Diseases, Alcoholic - enzymology; Male; Mice; Mice, Inbred C57BL; Models, Chemical; Oxidative Stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; Phosphorylation - drug effects; Phosphorylation - physiology; Protein Carbonylation - drug effects; Protein Carbonylation - physiology; Signal Transduction - drug effects; Signal Transduction - physiology; Alcohol; AMP-activated Kinase (AMPK); Oxidative Stress; Lipid Peroxidation; Liver
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M113.543942

The production of reactive aldehydes including 4-hydroxy-2-nonenal (4-HNE) is a key component of the pathogenesis in a spectrum of chronic inflammatory hepatic diseases including alcoholic liver disease (ALD). One consequence of ALD is increased oxidative stress and altered β-oxidation in hepatocytes. A major regulator of β-oxidation is 5′ AMP protein kinase (AMPK). In an in vitro cellular model, we identified AMPK as a direct target of 4-HNE adduction resulting in inhibition of both H2O2 and 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR)-induced downstream signaling. By employing biotin hydrazide capture, it was confirmed that 4-HNE treatment of cells resulted in carbonylation of AMPKα/β, which was not observed in untreated cells. Using a murine model of alcoholic liver disease, treatment with high concentrations of ethanol resulted in an increase in phosphorylated as well as carbonylated AMPKα. Despite increased AMPK phosphorylation, there was no significant change in phosphorylation of acetyl CoA carboxylase. Mass spectrometry identified Michael addition adducts of 4-HNE on Cys130, Cys174, Cys227, and Cys304 on recombinant AMPKα and Cys225 on recombinant AMPKβ. Molecular modeling analysis of identified 4-HNE adducts on AMPKα suggest that inhibition of AMPK occurs by steric hindrance of the active site pocket and by inhibition of hydrogen peroxide induced oxidation. The observed inhibition of AMPK by 4-HNE provides a novel mechanism for altered β-oxidation in ALD, and these data demonstrate for the first time that AMPK is subject to regulation by reactive aldehydes in vivo. Carbonylation of proteins contributes to increased hepatocellular damage during alcoholic liver disease. In a murine model of alcoholic liver disease, AMPK is covalently modified by reactive aldehydes reducing activity. Inhibition of AMPK activity by reactive aldehydes contributes to increased steatosis in alcoholic liver disease. This is the first report of AMPK carbonylation and inhibition during conditions of increased oxidative stress.