[Effect of HCV NS5A on STAT1 phosphorylation and nuclear translocation induced by IFN alpha-2b].
OBJECTIVE
To study the effect of HCV NS5A on the Janus kinase (JAK)/signal transducer and activation of transcription (STAT1) phosphorylation and translocation induced by IFN alpha-2b and to understand the possible molecular mechanism of HCV interferon resistance.


METHODS
Hepatocellular carcinoma cell line Huh7 was transiently transfected with HCV NS5A protein expression plasmid pCNS5A and blank plasmid pRC/CMV respectively; the cells of the same cell line, without transfection, served as controls. Immunocytochemistry was used to prove the successful transfection. Immunofluorescence and Western blot were performed to observe the difference in STAT1 phosphorylation and nuclear translocation between HCV NS5A-expressed and non-HCV NS5A-expressed cells after 30 minutes of IFN alpha-2b induction.


RESULTS
HCV NS5A protein was detected in the cytoplasm of Huh7 cells transfected with pCNS5A, indicating the successful transfection. In comparison to the blank plasmid-transfected and non-transfected group, STAT1 phosphorylation and sequential nuclear import were reduced in the presence of HCV NS5A protein.


CONCLUSIONS
HCV NS5A can, to some extent, inhibit phosphorylation and nuclear translocation of STAT1 in IFN alpha-2b-induced JAK/STAT pathway, which may be a possible mechanism of HCV interferon resistance.
Cao
Jie
J
Center for Liver Diseases, Second Xiangya Hospital, Central South University, Changsha 410011, China.
Zhou
Yang
Y
Gong
Guo-Zhong
GZ
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000998:Antiviral Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D024882:Drug Resistance, Viral / Q000187:drug effects; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*
D000998:Antiviral Agents; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D010750:Phosphoproteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D017361:Viral Nonstructural Proteins; C532378:nonstructural phosphoprotein 5A, GB virus type C