Hepatitis C virus (HCV) can cause acute and chronic hepatitis and is also a major cause of hepatocellular carcinoma. This virus has a positive-stranded RNA genome which encodes a polyprotein of approximately 3,010 amino acids. The core protein is located at the amino terminus of the polyprotein sequence. The HCV core protein sequence can produce two major products with length of 191 a.a. (P21) and 173 a.a. (P19), respectively, and a minor product with a length of approximately 151 a.a. These core proteins could bind to the 5' untranslated region (UTR) of the HCV genome. This binding may be important for regulating translation, replication and/or packaging of the HCV genomic RNA. The first three specific aims of this proposal is to continue our previous studies to examine the mechanism that regulates the expression of the core proteins, the role of individual core proteins in the life cycle of HCV, and how and why the core protein binds to the 5'UTR of the HCV genome. We have recently identified a deletion mutant of the HCV genome. This finding raises the possibility that it may be feasible to perform deletion mapping experiments to characterize the cis-acting elements required for the replication of the HCV genome. The fourth specific aim of this proposal is to investigate this possibility. The fifth specific aim is to investigate the possible functions of cellular protein factors which could bind to the 5'UTR of the HCV genome. The goal of this aim is to investigate the biological meanings of this finding. Thus, there are a total of five specific aims in this application.
These specific aims are designed to continue our present research to study the replication cycle of HCV. We believe the knowledge gained from our studies will eventually improve the diagnosis and treatments for the diseases caused by HCV.

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1
Fiscal Year
1996
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Liu, Helene Minyi; Aizaki, Hideki; Machida, Keigo et al. (2012) Hepatitis C virus translation preferentially depends on active RNA replication. PLoS One 7:e43600
Machida, Keigo; McNamara, George; Cheng, Kevin T-H et al. (2010) Hepatitis C virus inhibits DNA damage repair through reactive oxygen and nitrogen species and by interfering with the ATM-NBS1/Mre11/Rad50 DNA repair pathway in monocytes and hepatocytes. J Immunol 185:6985-98
Machida, Keigo; Liu, Jian-Chang; McNamara, George et al. (2009) Hepatitis C virus causes uncoupling of mitotic checkpoint and chromosomal polyploidy through the Rb pathway. J Virol 83:12590-600
Machida, Keigo; Tsukamoto, Hidekazu; Mkrtchyan, Hasmik et al. (2009) Toll-like receptor 4 mediates synergism between alcohol and HCV in hepatic oncogenesis involving stem cell marker Nanog. Proc Natl Acad Sci U S A 106:1548-53
Machida, Keigo; Kondo, Yasuteru; Huang, Jeffrey Y et al. (2008) Hepatitis C virus (HCV)-induced immunoglobulin hypermutation reduces the affinity and neutralizing activities of antibodies against HCV envelope protein. J Virol 82:6711-20
Lai, Chao-Kuen; Jeng, King-Song; Machida, Keigo et al. (2008) Hepatitis C virus NS3/4A protein interacts with ATM, impairs DNA repair and enhances sensitivity to ionizing radiation. Virology 370:295-309
Aswad, Fred; Dennert, Gunther (2006) P2X7 receptor expression levels determine lethal effects of a purine based danger signal in T lymphocytes. Cell Immunol 243:58-65
Kawamura, Hiroki; Aswad, Fred; Minagawa, Masahiro et al. (2006) P2X7 receptors regulate NKT cells in autoimmune hepatitis. J Immunol 176:2152-60
Machida, Keigo; Cheng, Kevin T-H; Lai, Chao-Kuen et al. (2006) Hepatitis C virus triggers mitochondrial permeability transition with production of reactive oxygen species, leading to DNA damage and STAT3 activation. J Virol 80:7199-207
Dennert, Gunther; Aswad, Fred (2006) The role of NKT cells in animal models of autoimmune hepatitis. Crit Rev Immunol 26:453-73

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