This project will continue the previous effects of hepatitis C virus (HCV) proteins on host function. Previous efforts have demonstrated that HCV envelope protein E2 can inhibit cellular protein kinase PKR, thus interfering with the effects of interferon. Furthermore, NS5a protein can interact with several cellular proteins, either directly or indirectly interfering with the actions of interferon and also affecting other cellular functions. In this project period, this laboratory will concentrate on the potential effects of these viral proteins on interferon activities in the context of full-length viral polyproteins. First, inducible liver-derived cell lines expressing the full-length HCV proteins will be established. These cell lines will then be used to perform the following studies: 1) Investigation of the effects of HCV polyproteins on PKR activities, including PKR phosphorylation, translation activities and NfkappaB activation, and their possible effects on apoptosis and tumor formation. The effects of these viral proteins will be compared with the effects of expression of E2 or NS5a proteins alone. 2) Characterization of HCV proteins on the antiviral effects of interferon, including the effects on the inhibition of encephalomyocarditis virus or vesicular stomatitis virus replication and interferon-induced effector proteins, such as MHC class I protein. 3) Exploration of other potential effects of NS5a on host functions, with emphasis on the effects on the FK506-binding proteins and vesicle transport proteins (VAP proteins). These projects are expected to contribute to the understanding of the mechanism of HCV resistance to interferon and to the improvement of interferon therapy in the future.

Project Start
2001-09-01
Project End
2002-08-31
Budget Start
Budget End
Support Year
6
Fiscal Year
2001
Total Cost
Indirect Cost
Name
University of Southern California
Department
Type
DUNS #
041544081
City
Los Angeles
State
CA
Country
United States
Zip Code
90033
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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