Chronic ethanol treatment of human hepatocytes inhibits the activation of the insulin signaling pathway by increasing cytosolic free calcium levels

  • Authors:
    • Yi‑Min Chen
    • Jin‑Fang Zhao
    • Yong‑Lin Liu
    • Jie Chen
    • Rong‑Lin Jiang
  • View Affiliations

  • Published online on: July 13, 2015     https://doi.org/10.3892/ijmm.2015.2282
  • Pages: 739-746
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Abstract

The present study aimed to investigate the effects of ethanol treatment on the induction of intracellular calcium ([Ca2+]i) levels and the inhibition of the activation of the insulin signaling pathway in human hepatocytes. L‑02 cells were treated with various concentrations of ethanol for different periods of time. Cell viability and alanine aminotransferase (ALT)/aspartate aminotransferase (AST) leakage in the culture supernatant were evaluated. Changes in [Ca2+]i levels were detected by flow cytometry and confocal microscopy. Total RNA and protein were extracted to examine the mRNA and protein levels of insulin receptor substrate (IRS)1, IRS2, phosphatidylinositol 3‑kinase (PI3K) and glucose transporter 2 (GLUT2) by reverse transcription-quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis, respectively. Furthermore, insulin was added to the ethanol‑treated L‑02 cells, and the phosphorylation levels of PI3K and protein kinase B (PKB) were determined by western blot analysis before and after Ca2+ blockage. No significant changes were observed in cell viability, [Ca2+]i levels and in the expression and phosphorylation levels of insulin signal transduction molecules when the L‑02 cells were treated with 0.5 or 1% ethanol. However, treatment with 2 or 4% ethanol resulted in a significant decrease in cell viability and in the mRNA levels of IRS1, IRS2, PI3K (p85α) and GLUT2, as well as in an increase in ALT/AST leakage and in the [Ca2+]i levels (P<0.05). The expression and phosphorylation levels of PI3K (p85α) and PKB were also inhibited by treatment with 2 or 4% ethanol. These cytological effects induced by ethanol treatment were partially reversed by Ca2+ blockage. These results suggest that ethanol treatment inhibits the activation of the insulin signal transduction pathway in a dose‑, time‑ and Ca2+‑dependent manner. The inhibition of IRS1/2, PI3K (p85α), PKB and GLUT2 expression and of PI3K (p85α) and PKB phosphorylation by the high concentrations of ethanol may be the core molecular mechanism of ethanol-induced insulin resistance, and may be related to the induction of [Ca2+]i levels.
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September-2015
Volume 36 Issue 3

Print ISSN: 1107-3756
Online ISSN:1791-244X

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Spandidos Publications style
Chen YM, Zhao JF, Liu YL, Chen J and Jiang RL: Chronic ethanol treatment of human hepatocytes inhibits the activation of the insulin signaling pathway by increasing cytosolic free calcium levels. Int J Mol Med 36: 739-746, 2015
APA
Chen, Y., Zhao, J., Liu, Y., Chen, J., & Jiang, R. (2015). Chronic ethanol treatment of human hepatocytes inhibits the activation of the insulin signaling pathway by increasing cytosolic free calcium levels. International Journal of Molecular Medicine, 36, 739-746. https://doi.org/10.3892/ijmm.2015.2282
MLA
Chen, Y., Zhao, J., Liu, Y., Chen, J., Jiang, R."Chronic ethanol treatment of human hepatocytes inhibits the activation of the insulin signaling pathway by increasing cytosolic free calcium levels". International Journal of Molecular Medicine 36.3 (2015): 739-746.
Chicago
Chen, Y., Zhao, J., Liu, Y., Chen, J., Jiang, R."Chronic ethanol treatment of human hepatocytes inhibits the activation of the insulin signaling pathway by increasing cytosolic free calcium levels". International Journal of Molecular Medicine 36, no. 3 (2015): 739-746. https://doi.org/10.3892/ijmm.2015.2282