| Co-Investigator(Kenkyū-buntansha) |
KATO Naoya University of Tokyo Faculty of Medicine, Assistant, 医学部・附属病院, 助手 (90313220)
SHIRATORI Yasushi University of Tokyo Faculty of Medicine, Lecturer, 医学部・附属病院, 講師 (70196624)
OMATA Masao University of Tokyo Faculty of Medicine, Professor, 医学部・附属病院, 教授 (90125914)
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| Research Abstract |
In this study, it was revealed that the NS5A protein, without its 146 N-terminal amino acids and fused to the DNA-binding domain of GAL4 strongly activates transcription in yeast and human hepatoma cells. Analysis of NS5A protein deletion mutants revealed that the domain of transcriptional activation exists in the central region of the NS5A protein. This region contains two acidic regions and one proline-rich region. Because NS5A protein is revealed to be a potent transcriptional transactivator, we examined the interaction of NS5A with general transcription factors in vivo to investigate how NS5A stimulates transcription. We found that NS5A binds to the human TATA box-binding protein (TBP). a major component of transcription factor for RNA polymerase II D (TFIID). We also observed an interaction between NS5A and a group of human TBP-associated factors (hTAFs), including TAFィイD2IIィエD270, hTAFィイD2IIィエD232/31, hTAFィイD2IIィエD228, hTAFィイD2IIィエD220, and hTAFィイD2IIィエD218. Further deletion analysis of NS5A revealed that the C-terminus of NS5A, ranging from amino acids 2153 to 2449, is important for its interactions with TFIID components. To clarify the effects of HCV infection on hepatocytes, we analyzed the influence of 7 HCV (core, NS2, NS3, NS4A, NS4B, NS5A, and NS5B) proteins on 5 well-defined intracellular signaling pathways associated with cell proliferation, differentiation, and apoptosis by use of a reporter assay. Of 7 HCV proteins, core protein had the strongest influence on intracellular signals, especially NF-κB-, AP-1-, and SRE-associated pathways. HCV NS4B also activated NF-κB pathway. Moreover, we found that core protein interacts with p53 and modulates p53-dependent promoter activities during HCV infection.
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