Hepatitis C Virus Nonstructural Protein 5A Inhibits Tumor Necrosis Factor-Alpha-Mediated Apoptosis in Huh7 Cells

J Infect Dis. 2003 Nov 15;188(10):1537-44. doi: 10.1086/379253. Epub 2003 Nov 11.

Abstract

To analyze the influence of hepatitis C virus nonstructural protein 5A (NS5A) on apoptosis, we established Huh7 cells that stably express NS5A, and induced apoptosis using tumor necrosis factor (TNF)-alpha. The viability of control Huh7 cells was reduced to 40%, compared with untreated cells, after TNF-alpha treatment, whereas that of Huh7-NS5A cells was reduced only to 80%. DNA fragmentation also decreased to <50% in Huh7-NS5A compared with control cells. Nuclear factor-kappaB activation was the same in both cell types, whereas caspase-8, -9, and -3 activity was decreased in Huh7-NS5A cells, compared with control cells, which indicates that the inhibition of caspase-8 activation is responsible for the antiapoptotic effect of the NS5A protein. The coexpression of NS5A did not inhibit apoptosis induced by caspase-8 or Fas-associating death domain protein expression. These findings suggest that the NS5A protein inhibits the apoptotic effect of TNF-alpha upstream of caspase-8 in the apoptosis cascade.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / physiology*
  • Arabidopsis Proteins / physiology
  • Caspase 8
  • Caspase 9
  • Caspases / physiology
  • Cell Line
  • Dactinomycin / pharmacology
  • Fatty Acid Desaturases / physiology
  • Hepacivirus / genetics
  • Hepacivirus / metabolism
  • Hepatitis C / pathology
  • Hepatocytes / cytology
  • Humans
  • NF-kappa B / physiology
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Oligoribonucleotides, Antisense / genetics
  • Oligoribonucleotides, Antisense / pharmacology
  • Signal Transduction / immunology*
  • Transfection
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Tumor Necrosis Factor-alpha / physiology
  • Viral Nonstructural Proteins / genetics
  • Viral Nonstructural Proteins / physiology*

Substances

  • Arabidopsis Proteins
  • NF-kappa B
  • NS-5 protein, hepatitis C virus
  • Nucleic Acid Synthesis Inhibitors
  • Oligoribonucleotides, Antisense
  • Tumor Necrosis Factor-alpha
  • Viral Nonstructural Proteins
  • Dactinomycin
  • Fatty Acid Desaturases
  • Fad7 protein, Arabidopsis
  • CASP8 protein, human
  • CASP9 protein, human
  • Caspase 8
  • Caspase 9
  • Caspases