Hepatitis C virus non-structural 5A protein can enhance full-length core protein-induced nuclear factor-kappaB activation.
OBJECTIVE
To study the effects of hepatitis C virus (HCV) core and non-structural 5A (NS5A) proteins on nuclear factor-kappaB (NF-kappaB) activity for understanding their biological function on chronic hepatitis caused by HCV infection.


METHODS
Luciferase assay was used to measure the activity of NF-kappaB in three different cell lines cotransfected with a series of deletion mutants of core protein alone or together with NS5A protein using pNF-kappaB-Luc as a reporter plasmid. Western blot and indirect immunofluorescence assays were used to confirm the expression of proteins and to detect their subcellular localization, respectively. Furthermore, Western blot was also used to detect the expression levels of NF-kappaB/p65, NF-kappaB/p50, and inhibitor kappaB-a (IkappaB-a).


RESULTS
The wild-type core protein (C191) and its mutant segments (C173 and C158) could activate NF-kappaB in Huh7 cells only and activation caused by (C191) could be enhanced by NS5A protein. Moreover, the full-length core protein and its different deletion mutants alone or together with NS5A protein did not enhance the expression level of NF-kappaB. The NF-kappaB activity was augmented due to the dissociation of NF-kappaB-IkappaB complex and the degradation of IkappaB-a.


CONCLUSIONS
NF-kappaB is the key transcription factor that can activate many genes that are involved in the cellular immune response and inflammation. Coexpression of the full-length core protein along with NS5A can enhance the NF-kappaB activation, and this activation may play a significant role in chronic liver diseases including hepatocellular carcinoma associated with HCV infection.
Liao
Qing-Jiao
QJ
State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan 430072, Hubei Province, China.
Ye
Lin-Bai
LB
Timani
Khalid Amine
KA
She
Ying-Long
YL
Yang
Xiao-Jun
XJ
Ye
Li
L
Wu
Zheng-Hui
ZH
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D006367:HeLa Cells; D016174:Hepacivirus / Q000235:genetics*; D019698:Hepatitis C, Chronic / Q000378:metabolism / Q000821:virology*; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
D016328:NF-kappa B; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase