Acetaldehyde Disrupts Interferon Alpha Signaling in Hepatitis C Virus-Infected Liver Cells by Up-Regulating USP18

Murali Ganesan, Larisa Y Poluektova, Dean J. Tuma, Kusum Kharbanda, Natalia A Osna

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Background: Alcohol consumption exacerbates the pathogenesis of hepatitis C virus (HCV) infection and worsens disease outcomes. The exact reasons are not clear yet, but they might be partially attributed to the ability of alcohol to further suppress the innate immunity. Innate immunity is known to be already decreased by HCV in liver cells. Methods: In this study, we aimed to explore the mechanisms of how alcohol metabolism dysregulates IFNα signaling (STAT1 phosphorylation) in HCV+ hepatoma cells. To this end, CYP2E1+ Huh7.5 cells were infected with HCV and exposed to the acetaldehyde (Ach) generating system (AGS). Results: Continuously produced Ach suppressed IFNα-induced STAT1 phosphorylation, but increased the level of a protease, USP18 (both measured by Western blot), which interferes with IFNα signaling. Induction of USP18 by Ach was confirmed in primary human hepatocyte cultures and in livers of ethanol-fed HCV transgenic mice. Silencing of USP18 by specific siRNA attenuated the pSTAT1 suppression by Ach. The mechanism by which Ach down-regulates pSTAT1 is related to an enhanced interaction between IFNαR2 and USP18 that finally dysregulates the cross talk between the IFN receptor on the cell surface and STAT1. Furthermore, Ach decreases ISGylation of STAT1 (protein conjugation of a small ubiquitin-like modifier, ISG15, Western blot), which preserves STAT1 activation. Suppressed ISGylation leads to an increase in STAT1 K48 polyubiquitination which allows pSTAT1 degrading by proteasome. Conclusions: We conclude that Ach disrupts IFNα-induced STAT1 phosphorylation by the up-regulation of USP18 to block the innate immunity protection in HCV-infected liver cells, thereby contributing to HCV-alcohol pathogenesis. This, in part, may explain the mechanism of HCV-infection exacerbation/progression in alcohol-abusing patients.

Original languageEnglish (US)
Pages (from-to)2329-2338
Number of pages10
JournalAlcoholism: Clinical and Experimental Research
Volume40
Issue number11
DOIs
StatePublished - Nov 1 2016

Fingerprint

Acetaldehyde
Viruses
Interferon-alpha
Hepacivirus
Liver
Alcohols
Phosphorylation
Innate Immunity
Virus Diseases
Western Blotting
STAT1 Transcription Factor
Cytochrome P-450 CYP2E1
Aptitude
Cell Surface Receptors
Proteasome Endopeptidase Complex
Ubiquitin
Metabolism
Alcohol Drinking
Small Interfering RNA
Transgenic Mice

Keywords

  • Acetaldehyde
  • Alcohol
  • Hepatitis C Virus
  • IFNα Signaling
  • ISGylation
  • USP18

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Toxicology
  • Psychiatry and Mental health

Cite this

@article{7f33a2f33a1b44fa9b85f742d93fe0e3,
title = "Acetaldehyde Disrupts Interferon Alpha Signaling in Hepatitis C Virus-Infected Liver Cells by Up-Regulating USP18",
abstract = "Background: Alcohol consumption exacerbates the pathogenesis of hepatitis C virus (HCV) infection and worsens disease outcomes. The exact reasons are not clear yet, but they might be partially attributed to the ability of alcohol to further suppress the innate immunity. Innate immunity is known to be already decreased by HCV in liver cells. Methods: In this study, we aimed to explore the mechanisms of how alcohol metabolism dysregulates IFNα signaling (STAT1 phosphorylation) in HCV+ hepatoma cells. To this end, CYP2E1+ Huh7.5 cells were infected with HCV and exposed to the acetaldehyde (Ach) generating system (AGS). Results: Continuously produced Ach suppressed IFNα-induced STAT1 phosphorylation, but increased the level of a protease, USP18 (both measured by Western blot), which interferes with IFNα signaling. Induction of USP18 by Ach was confirmed in primary human hepatocyte cultures and in livers of ethanol-fed HCV transgenic mice. Silencing of USP18 by specific siRNA attenuated the pSTAT1 suppression by Ach. The mechanism by which Ach down-regulates pSTAT1 is related to an enhanced interaction between IFNαR2 and USP18 that finally dysregulates the cross talk between the IFN receptor on the cell surface and STAT1. Furthermore, Ach decreases ISGylation of STAT1 (protein conjugation of a small ubiquitin-like modifier, ISG15, Western blot), which preserves STAT1 activation. Suppressed ISGylation leads to an increase in STAT1 K48 polyubiquitination which allows pSTAT1 degrading by proteasome. Conclusions: We conclude that Ach disrupts IFNα-induced STAT1 phosphorylation by the up-regulation of USP18 to block the innate immunity protection in HCV-infected liver cells, thereby contributing to HCV-alcohol pathogenesis. This, in part, may explain the mechanism of HCV-infection exacerbation/progression in alcohol-abusing patients.",
keywords = "Acetaldehyde, Alcohol, Hepatitis C Virus, IFNα Signaling, ISGylation, USP18",
author = "Murali Ganesan and Poluektova, {Larisa Y} and Tuma, {Dean J.} and Kusum Kharbanda and Osna, {Natalia A}",
year = "2016",
month = "11",
day = "1",
doi = "10.1111/acer.13226",
language = "English (US)",
volume = "40",
pages = "2329--2338",
journal = "Alcoholism: Clinical and Experimental Research",
issn = "0145-6008",
publisher = "Wiley-Blackwell",
number = "11",

}

TY - JOUR

T1 - Acetaldehyde Disrupts Interferon Alpha Signaling in Hepatitis C Virus-Infected Liver Cells by Up-Regulating USP18

AU - Ganesan, Murali

AU - Poluektova, Larisa Y

AU - Tuma, Dean J.

AU - Kharbanda, Kusum

AU - Osna, Natalia A

PY - 2016/11/1

Y1 - 2016/11/1

N2 - Background: Alcohol consumption exacerbates the pathogenesis of hepatitis C virus (HCV) infection and worsens disease outcomes. The exact reasons are not clear yet, but they might be partially attributed to the ability of alcohol to further suppress the innate immunity. Innate immunity is known to be already decreased by HCV in liver cells. Methods: In this study, we aimed to explore the mechanisms of how alcohol metabolism dysregulates IFNα signaling (STAT1 phosphorylation) in HCV+ hepatoma cells. To this end, CYP2E1+ Huh7.5 cells were infected with HCV and exposed to the acetaldehyde (Ach) generating system (AGS). Results: Continuously produced Ach suppressed IFNα-induced STAT1 phosphorylation, but increased the level of a protease, USP18 (both measured by Western blot), which interferes with IFNα signaling. Induction of USP18 by Ach was confirmed in primary human hepatocyte cultures and in livers of ethanol-fed HCV transgenic mice. Silencing of USP18 by specific siRNA attenuated the pSTAT1 suppression by Ach. The mechanism by which Ach down-regulates pSTAT1 is related to an enhanced interaction between IFNαR2 and USP18 that finally dysregulates the cross talk between the IFN receptor on the cell surface and STAT1. Furthermore, Ach decreases ISGylation of STAT1 (protein conjugation of a small ubiquitin-like modifier, ISG15, Western blot), which preserves STAT1 activation. Suppressed ISGylation leads to an increase in STAT1 K48 polyubiquitination which allows pSTAT1 degrading by proteasome. Conclusions: We conclude that Ach disrupts IFNα-induced STAT1 phosphorylation by the up-regulation of USP18 to block the innate immunity protection in HCV-infected liver cells, thereby contributing to HCV-alcohol pathogenesis. This, in part, may explain the mechanism of HCV-infection exacerbation/progression in alcohol-abusing patients.

AB - Background: Alcohol consumption exacerbates the pathogenesis of hepatitis C virus (HCV) infection and worsens disease outcomes. The exact reasons are not clear yet, but they might be partially attributed to the ability of alcohol to further suppress the innate immunity. Innate immunity is known to be already decreased by HCV in liver cells. Methods: In this study, we aimed to explore the mechanisms of how alcohol metabolism dysregulates IFNα signaling (STAT1 phosphorylation) in HCV+ hepatoma cells. To this end, CYP2E1+ Huh7.5 cells were infected with HCV and exposed to the acetaldehyde (Ach) generating system (AGS). Results: Continuously produced Ach suppressed IFNα-induced STAT1 phosphorylation, but increased the level of a protease, USP18 (both measured by Western blot), which interferes with IFNα signaling. Induction of USP18 by Ach was confirmed in primary human hepatocyte cultures and in livers of ethanol-fed HCV transgenic mice. Silencing of USP18 by specific siRNA attenuated the pSTAT1 suppression by Ach. The mechanism by which Ach down-regulates pSTAT1 is related to an enhanced interaction between IFNαR2 and USP18 that finally dysregulates the cross talk between the IFN receptor on the cell surface and STAT1. Furthermore, Ach decreases ISGylation of STAT1 (protein conjugation of a small ubiquitin-like modifier, ISG15, Western blot), which preserves STAT1 activation. Suppressed ISGylation leads to an increase in STAT1 K48 polyubiquitination which allows pSTAT1 degrading by proteasome. Conclusions: We conclude that Ach disrupts IFNα-induced STAT1 phosphorylation by the up-regulation of USP18 to block the innate immunity protection in HCV-infected liver cells, thereby contributing to HCV-alcohol pathogenesis. This, in part, may explain the mechanism of HCV-infection exacerbation/progression in alcohol-abusing patients.

KW - Acetaldehyde

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KW - Hepatitis C Virus

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KW - ISGylation

KW - USP18

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