Viral Hepatitis
Copyright ©2007 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Aug 14, 2007; 13(30): 4080-4084
Published online Aug 14, 2007. doi: 10.3748/wjg.v13.i30.4080
Hepatitis C Virus non-structural 5A abrogates signal transducer and activator of transcription-1 nucleartranslocation induced by IFN-α through dephosphorylation
Guo-Zhong Gong, Jie Cao, Yong-Fang Jiang, Yang Zhou, Bo Liu
Guo-Zhong Gong, Jie Cao, Yong-Fang Jiang, Yang Zhou, Bo Liu, Institute of Hepatology and Department of Infectious Diseases, The Second Xiangya Hospital, Central South University, Changsha 410011, Hunan Province, China
Author contributions: All authors contributed equally to the work.
Supported by National Natural Science Foundation of China, No. 39670671, No. 30471531
Correspondence to: Dr. Guo-Zhong Gong, Institute of Hepatology and Department of Infectious Diseases, The Second Xiangya Hospital, Central South University, Changsha 410011, Hunan Province, China. guozhonggong@yahoo.com
Telephone: +86-731-5292173 Fax: +86-731-5292173
Received: March 6, 2007
Revised: March 13, 2007
Accepted: March 28, 2007
Published online: August 14, 2007
Abstract

AIM: To study the effect of Hepatitis C virus non-structural 5A (HCV NS5A) on IFNα induced signal transducer and activator of transcription-1 (STAT1) phosphorylation and nuclear translocation.

METHODS: Expression of STAT1 Tyr701 phosphorylation at different time points was confirmed by Western blot, and the time point when p-STAT1 expressed most, was taken as the IFN induction time for further studies. Immunocytochemistry was used to confirm the successful transient transfection of NS5A expression plasmid. Immunofluorescene was performed to observe if there was any difference in IFNα-induced STAT1 phosphorylation and nuclear translocation between HCV NS5A-expressed and non-HCV NS5A-expressed cells. Western blot was used to compare the phosphorylated STAT1 protein of the cells.

RESULTS: Expression of HCV NS5A was found in the cytoplasm of PCNS5A-transfected Huh7 cells, but not in the PRC/CMV transfected or non-transfected cells. STAT1 Tyr701 phosphorylation was found strongest in 30 min of IFN induction. STAT1 phosphorylation and nuclear import were much less in the presence of HCV NS5A protein in contrast to PRC/CMV-transfected and non-transfected cells under fluorescent microscopy, which was further confirmed by Western blot.

CONCLUSION: HCV NS5A expression plasmid is successfully transfected into Huh7 cells and HCV NS5A protein is expressed in the cytoplasm of the cells. IFN-α is able to induce STAT1 phosphrylation and nuclear translocation, and this effect is inhibited by HCV NS5A protein, which might be another possible resistance mechanism to interferon alpha therapy.

Keywords: Hepatitis C virus nonstructural protein 5A; IFN-α; Signal transducer and activator of transcription (STAT1); Phosphorylation; Nuclear translocation