Abstract
The nonstructural protein 5A (NS5A) encoded by the human hepatitis C virus RNA genome is shown here to induce the activation of NF-kappaB and STAT-3 transcription factors from its cytoplasmic residence via oxidative stress. NS5A causes the disturbance of intracellular calcium. Ca2+ signaling triggers the elevation of reactive oxygen species in mitochondria, leading to the translocation of NF-kappaB and STAT-3 into the nucleus. Evidence is presented for the constitutive activation of STAT-3 by NS5A. In the presence of antioxidants [pyrrolidine dithiocarbamate (PDTC), N-acetyl l-cysteine (NAC)] or Ca2+ chelators (EGTA-AM, TMB-8), NS5A-induced activation of NF-kappaB and STAT-3 was eliminated. These results provide an insight into the mechanism by which NS5A can alter intracellular events relevant to liver pathogenesis associated with the viral infection.
MeSH terms
- Acetylcysteine / pharmacology
- Antioxidants / pharmacology
- Calcium / metabolism*
- Calcium Signaling* / drug effects
- Carcinoma, Hepatocellular / pathology
- Chelating Agents / pharmacology
- DNA-Binding Proteins / metabolism*
- Egtazic Acid / analogs & derivatives
- Egtazic Acid / pharmacology
- Gallic Acid / analogs & derivatives
- Gallic Acid / pharmacology
- Gene Expression Regulation, Neoplastic
- Gene Expression Regulation, Viral / drug effects
- Gene Expression Regulation, Viral / physiology*
- Genes, Reporter
- Hepacivirus / genetics
- Hepacivirus / metabolism*
- Humans
- Liver Neoplasms / pathology
- Luciferases / biosynthesis
- Luciferases / genetics
- NF-kappa B / metabolism*
- Neoplasm Proteins / metabolism
- Oxidative Stress* / drug effects
- Pyrrolidines / pharmacology
- Reactive Oxygen Species
- Recombinant Fusion Proteins / biosynthesis
- Recombinant Fusion Proteins / genetics
- STAT3 Transcription Factor
- Thiocarbamates / pharmacology
- Trans-Activators / metabolism*
- Transcription, Genetic / drug effects
- Transfection
- Tumor Cells, Cultured
- Viral Nonstructural Proteins / physiology*
Substances
- Antioxidants
- Chelating Agents
- DNA-Binding Proteins
- NF-kappa B
- Neoplasm Proteins
- Pyrrolidines
- Reactive Oxygen Species
- Recombinant Fusion Proteins
- STAT3 Transcription Factor
- STAT3 protein, human
- Thiocarbamates
- Trans-Activators
- Viral Nonstructural Proteins
- pyrrolidine dithiocarbamic acid
- Egtazic Acid
- 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate
- Gallic Acid
- EGTA acetoxymethyl ester
- Luciferases
- NS-5 protein, hepatitis C virus
- Calcium
- Acetylcysteine