Summary of Research Project Results under JSPS FY2001
"Research for the Future Program"

1.Research Institution Kyoto University
2.Research Area Life Sciences
3.Research Field Infectious Diseases and Bioregulation
4.Term of Project FY 1997 〜 FY 2001
5.Project Number 97L00707
6.Title of Project Molecular Mechanism of Biological Defense against Retrovirus and Hepatitis Virus Infection

7.Project Leader
Name Institution,Department Title of Position
Junji, Yodoi Kyoto University, Institute for Virus Research Professor

8.Core Members

Names Institution,Department Title of Position
Kunitada, Shimotohno Kyoto University, Institute for Virus Research Professor
Arimichi, Takabayashi Kyoto University, Graduate School of Medicine Associate Professor

9.Summary of Research Results

We have demonstrated that members of the thioredoxin (TRX) system including TRX, mitochondria specific TRX2 plays important roles in the regulation of viral persistent infection and cell death by redox regulation. We showed that the TRX2 gene is essential for cell survival and regulates apoptosis using the DT-40 knock out system. We also studied extracellular functions of TRX and clarified that TRX suppresses neutrophil extravasation into inflammatory site. Influenza-induced pneumonia and Listeria infection as well as cytokine -induced interstitial pneumonia was suppressed in TRX transgenic mice, suggesting a protective role of TRX against inflammation. We also revealed the regulatory mechanism of the TRX gene through the antioxidant responsive element, suggesting the coordinated role of the TRX system and the glutathione system against oxidative stress. We newly identified TRX binding protein-2/ vitamine D3 up-regulated protein 1 (VDUP-1) as a negative regulator of TRX. TBP-2 expression was markedly abrogated in HTLV-I infected cell lines. Loss of TBP-2 expression was associated with loss of IL-2 dependency in these cell lines. TBP-2 also has a growth suppressing activity, indicating a role of TBP-2 as a tumor suppressor. Therefore, analysis of TBP-2/VDUP-1 family genes seems very important for creating a new diagnostic and therapeutic approach in HTLV-I infection.
We established an assay system for assessing natural killer (NK) cell activity by measuring the mitochondrial membrane potential (Dym). The levels of Dym, in NK cells were decreased in HCV infected patients and virus-positive patients, suggesting that NK cells in the patients who could not eliminate HCV may have impaired functions.
We analyzed the role of HCV core and non-structural protein, NS5A in the regulation of cell proliferation. We showed that core protein expressing cells were resistant to apoptotoic stimulation and this ability was correlated with the ability of core to activate NF-κB. NS5A interferes the PKR function so that the NS5A expressing cells become resistant to interferon treatment. We revealed that the C-terminal region of NS5A is involved in this regulation.
Inefficient replication of HCV in a tissue culture hampers to study the pathogenic role of this virus. We established the cell line in which a part of HCV genome replicates efficiently. This system may provide a new clue for HCV research.

10.Key Words

(1)thioredoxin、(2)thioredoxin 2、(3)HTLV-I
(4)HCV、(5)ATL、(6)thioredoxin binding protein-2 (TBP-2)/VDUP-1