| Project/Area Number |
01480513
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Laboratory animal science
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| Research Institution | The University of Tokushima |
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Principal Investigator |
MATSUMOTO Kozo Institute for Animal Experimentation Professors, 医学部, 助教授 (00002246)
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| Co-Investigator(Kenkyū-buntansha) |
AGUI Takashi Institute for Animal Experimentation Research Associates, 医学部, 助手 (00212457)
IZUMI Keisuke School of Medicine Associate Professors, 医学部, 助教授 (30116777)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1990: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1989: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Keywords | Hepatitis Rat / Cancerous Rat / GST / Immunodeficiency / Recombinant Rat / Congenic Rat / リコンビナント肝炎・肝癌ラット / コンジェニック肝炎・肝癌ラット / GST異常 |
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| Research Abstract |
Abstract
We have examined for expression of the liver glutatione-dependent enzyme in relation to abnormal copper accumulation in a novel mutant rat (LEC) in which liver injury occurs and then hepatocellular carcinoma spontaneously develops. We have found that the copper concentration gradually increased up to 49-fold, but then decreased about to 20-fold in LEC rat liver as compared to that in age-matched normal rat. Levels of reduced glutathione were increased in LEC rat liver with age. The activity of glutathione S-transferases was unchanged, but that of selenium-dependent glutathione peroxidase decreased in LEC rat at the old age. We have found that relative expression of the glutatione S-transferase 1-1 was about 2 to 5-fold decrcase, while that of glutathione S-transferase 2-2 was 5 to 8-fold increase in the elution profiles from chromatofocusing in LEC rat liver. The levels of the subunits of glutathione S-transferases in rat liver cytosol were determined by Western blotting. The r
… More
esult shows that the relative content of the Ya subunit is about a half through the life time, while that of the Yc subunit is somewhat lower at the age of 1 month, but then 2-fold higher in LEC than in normal rat at the ages of 4. A corresponding decrease and increase in poly (A) RNAs coding for the Ya and Yc subunits were also observed by Northern blotting, respectively. Southern blot analysis showed no gene amplification for the Yc subunit. Our data suggest that the overexpression of glutathione S-transferase 2-2 is due to a selective regulation of the transcription stage for the YaYc gene family by abnormal copper accumulation in LEC mutant rat.
LEC rats appear to have a decrease serum IgG content in spite of normal levels of IgM and IgA, and the IgG deficiency is controlled by a single recessive gene which is designated as Igsr-1 (Matsumoto et al. 1989). We recently found that LEC rats have a markedly decreased number of CD4^+ T-cells due to arrest of maturation from CD4^+8^+ cells to CD4^+8^- cells in the thymus. It might be supposed that MHC class II antigen is not expressed in the thymus, but the antigen was expressed in LEC thymus which showed hypoplasia of the medulla (Agui et al. In press). However, there was a possibility that a dysfunctional mutation in MHC class II might cause a defect in positive selection from CD4^+8^+ to CD4^+8^- T-cells. Furtheremore it is of interest to investigate a relationship between helper T-cell deficiency and the selective IgG deficiency (Igsr-1), because low IgG level could be a consequence of the helper T-cell deficiency. Therefore, before LEC rats can be used as an animal model for studies on immunodeficiency, their novel mutation must be genetically characterized. In this study, we carried out genetic analyses of this T helper immunodeficiency using F_1 and backcross progeny of LEC and normal (either WKAH or BN) rats to determine if a single gene is responsible for the deficiency. We also carried out linkage analyses on the gene for this immunodeficiency and several loci including Igsr-1 and RT1 loci.
In conclusion, recombinant and congenic strains for hepatitis and immunodeficiency genes must be useful for studies on mechanisms of hepatocellular carcinoma in relation to immunodeficiency. We are now making CXA recombinant rats with 14F generation and third congenic strain with 4N generation. These new strains will be established during further 1 year and must be very useful for the studies described above. Less
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