Effect of ethanol on hydrogen peroxide-induced AMPK phosphorylation

Suthat Liangpunsakul, Sung Eun Wou, Yan Zeng, Ruth A. Ross, Hiremagalur N. Jayaram, David Crabb

Research output: Contribution to journalArticle

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Abstract

AMP-activated protein kinase (AMPK) responds to oxidative stress. Previous work has shown that ethanol treatment of cultured hepatoma cells and of mice inhibited the activity of AMPK and reduced the amount of AMPK protein. Ethanol generates oxidative stress in the liver. Since AMPK is activated by reactive oxygen species, it seems paradoxical that ethanol would inhibit AMPK in the hepatoma cells. In an attempt to understand the mechanism whereby ethanol inhibits AMPK, we studied the effect of ethanol on AMPK activation by exogenous hydrogen peroxide. The effects of ethanol, hydrogen peroxide, and inhibitors of protein phosphatase 2A (PP2A) [either okadaic acid or PP2A small interference RNA (siRNA)] on AMPK phosphorylation and activity were examined in rat hepatoma cells (H4IIEC3) and HeLa cells. In H4IIEC3 cells, hydrogen peroxide (H 2O2, 1 mM) transiently increased the level of phospho-AMPK to 1.5-fold over control (P < 0.05). Similar findings were observed in HeLa cells, which do not express the upstream AMPK kinase, LKB1. H2O 2 markedly increased the phosphorylation of LKB1 in H4IIEC3 cells. Ethanol significantly inhibited the phosphorylation of PKC-ζ, LKB1, and AMPK caused by exposure to H2O2. This inhibitory effect of ethanol required its metabolism. More importantly, the inhibitory effects of ethanol on H2O2-induced AMPK phosphorylation were attenuated by the presence of the PP2A inhibitor, okadaic acid, or PP2A siRNA. The inhibitory effect of ethanol on AMPK phosphorylation is exerted through the inhibition of PKC-ζ and LKB1 phosphorylation and the activation of PP2A.

Original languageEnglish
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume295
Issue number6
DOIs
StatePublished - Dec 2008

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AMP-Activated Protein Kinases
Hydrogen Peroxide
Ethanol
Phosphorylation
Protein Phosphatase 2
Hepatocellular Carcinoma
Okadaic Acid
Acid Phosphatase
RNA Interference
HeLa Cells
Oxidative Stress
Cultured Cells
Reactive Oxygen Species

Keywords

  • Protein phosphatase

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology (medical)
  • Physiology
  • Hepatology

Cite this

Effect of ethanol on hydrogen peroxide-induced AMPK phosphorylation. / Liangpunsakul, Suthat; Wou, Sung Eun; Zeng, Yan; Ross, Ruth A.; Jayaram, Hiremagalur N.; Crabb, David.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 295, No. 6, 12.2008.

Research output: Contribution to journalArticle

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