Defective translocation of PKCepsilon in EtOH-induced inhibition of Mg2+ accumulation in rat hepatocytes

Alcohol Clin Exp Res. 2010 Sep 1;34(9):1659-69. doi: 10.1111/j.1530-0277.2010.01252.x. Epub 2010 Jun 25.

Abstract

Background: Rats chronically fed ethanol for 3 weeks presented a marked decreased in total hepatic Mg(2+) content and required approximately 12 days to restore Mg(2+) homeostasis upon ethanol withdrawal. This study was aimed at investigating the mechanisms responsible for the EtOH-induced delay.

Methods: Hepatocytes from rats fed ethanol for 3 weeks (Lieber-De Carli diet-chronic model), rats re-fed a control diet for varying periods of time following ethanol withdrawal, and age-matched control rats fed a liquid or a pellet diet were used. As acute models, hepatocytes from control animals or HepG2 cells were exposed to varying doses of ethanol in vitro for 8 minutes.

Results: Hepatocytes from ethanol-fed rats presented a marked inhibition of Mg(2+) accumulation and a defective translocation of PKCepsilon to the cell membrane. Upon ethanol withdrawal, 12 days were necessary for PKCepsilon translocation and Mg(2+) accumulation to return to normal levels. Exposure of control hepatocytes or HepG2 cells to a dose of ethanol as low as 0.01% for 8 minutes was already sufficient to inhibit Mg(2+) accumulation and PKCepsilon translocation for more than 60 minutes. Also in this model, recovery of Mg(2+) accumulation was associated with restoration of PKCepsilon translocation. The use of specific antisense in HepG2 cells confirmed the involvement of PKCepsilon in modulating Mg(2+) accumulation.

Conclusions: Translocation of PKCepsilon isoform to the hepatocyte membrane is essential for Mg(2+) accumulation to occur. Both acute and chronic ethanol administrations inhibit Mg(2+) accumulation by specifically altering PKCepsilon translocation to the cell membrane.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antisense Elements (Genetics) / pharmacology
  • Cell Culture Techniques
  • Cells, Cultured
  • Ethanol / administration & dosage
  • Ethanol / pharmacology*
  • Hep G2 Cells
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism*
  • Homeostasis / drug effects
  • Humans
  • Magnesium / metabolism*
  • Male
  • Protein Kinase C-epsilon / metabolism*
  • Protein Transport / drug effects*
  • Rats
  • Rats, Sprague-Dawley
  • Time Factors

Substances

  • Antisense Elements (Genetics)
  • Ethanol
  • Protein Kinase C-epsilon
  • Magnesium