| Co-Investigator(Kenkyū-buntansha) |
SATO Eiji Hamamatsu University, School of Medicine, Res. Associate, 医学部, 助手 (70118751)
WU Yi-xin Hamamatsu University, School of Medicine, Res. Associate, 医学部, 助手 (60283363)
YOSHIDA Nobuaki University of Tokyo, Inst. Medical Science, Professor, 医科学研究所, 教授 (10250341)
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| Research Abstract |
Two lines of the transgenic mice in which the human Rb cDNA was controlled under the) kbp of rat hepatocyte nuclear factor-1 (HNF-1) promoter/enhancer were generated. Transgenic mice, line A (TGA) had about 11 copies of the transgenes per haploid and line B (TGB) had about 4 copies of the transgenes. By Western blot analysis, we observed that a large amount of Rb protein was expressed in the liver of TGA mice and a small amount of Rb protein was expressed in that of TGB mice. In control mice, injection of anti-Fas antibody and TNFα induced increase of GOT and GPT in serum, hemorrhages and hepatocyte apoptosis in the histology. However, in TGA mice, the increase in GOT and GPT was marginal and no hemorrhages and apoptosis were detected In TGB mice, the increase in GOT and GPT was moderate and apoptosis of the substantial number of hepatocytes was observed, but no hemorrhages. In order to investigate the molecular mechanism of anti-apoptotic condition, we did the western blot analysis of
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apoptosis-related proteins. Fas, Bcl-2, Bcl-X, Bid, Bad, ICE, CPP32, E2F1, E2F2, E2F3, E2F4, E2F5 and p53 proteins had no differences between control mice and Rb transgenic mice. However, the Bax protein was decreased in Rb transgenic mice compared to control mice. This suggests that the Bax protein is on e of the contributing proteins for the anti-apoptotic condition.
Next we investigated whether the Rb transgenic mice showed resistance to chemical carcinogenesis. We inject diethylnitrosamine into the peritoneal cavity at the age of 6 weeks and treated phenobarbital in drinking water for 35 weeks. After the experiment, the mice were sacrificed to make histological sections for counting the numbers of hepatocellular carcinoma and hepatic nodule. In control mice, a large number of nodules and several hepatocellular carcinoma were developed. In contrast, the number of nodules was greatly reduced and no hepatocellular carcinomas were detected in Rb transgenic mice. These results indicate that the Rb protein act as an anti apoptotic agent and an anti-tumorigenic agent in the liver in vivo. Less
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