Analysis on genomic Instability with aging in rats developed spontaneous hepaticis hepatoma Senior Research Scientist

由于编码铜-ATPase的ATP7B基因突变，大鼠的LEC(Long-Evans Cinnamon)突变株在肝脏中积累了铜。它会自发地发展成肝炎，然后是肝细胞癌和胆管纤维化。细胞内过量的铜被认为是通过铜(II)/铜(I)氧化还原循环产生的活性氧物种(ROS)以及与DNA的直接相互作用而导致DNA损伤。我们用携带LACI的Lambda穿梭载体的LEC和Big Blue F344大鼠交配，建立了1acl转基因LEC大鼠，并利用它们检测体内的体细胞突变率。24周龄时，用显色筛选技术分析了4只Big Blue F344大鼠和8只LacI转基因LEC大鼠的肝脏LacI突变频率。LacI转基因LEC大鼠的突变频率(平均+-SD)是大蓝大鼠的12.8+-8.3×10-5，25倍。转LacI基因LEC大鼠肝脏铜蓄积量为265±-72微克/g，是Big Blue F344大鼠肝脏铜蓄积量的53倍。LacI转基因LEC大鼠血浆谷草转氨酶和谷丙转氨酶水平也明显升高。我们推测，LEC大鼠肝脏中突变频率的显著增加可能在其肝癌的发生中起关键作用。

The LEC (Long-Evans Cinnamon) mutant strain of rat accumulates copper in the liver due to a mutation in the Atp7b gene, which encodeds a copper-ATPase. It spontaneously develops hepatitis, and subsequently hepatocellular carcinomas and cholangiofibrosis. Excess intracellular copper has been thought to induce DNA damage throughout reactive oxygen species (ROS) produced by Cu (II) /Cu (I) redox cycling and also by direct interaction with DNA.We developed 1acl transgenic LEC rats, by mating LEC and Big Blue F344 rats carrying a lambda shuttle vector harbo6ng the lacI and utilized them to examine rates of somatic mutation in vivo. At 24 weeks of age, the livers of four Big Blue F344 rats and of eight lacI transgenic LEC rats were analyzed for the mutant frequency of lacI using the color screening technique. The mutant frequencies (mean+-SD) in the lacI transgenic LEC rats was 12.8+-8.3 x 10-5,25-fold higher than that in Big Blue case. The level of copper accumulation in the livers of lacI transgenic LEC rats was 265+-72 micro g/g, 53-fold the amount in Big Blue F344 rats. Plasma levels of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, assayd as markers of hepatitis development, were also much higher in lacI transgenic LEC rats. We hypothesize that the remarkable increase in mutant frequency in the LEC rat liver may play a crucial role in its hepatocarcinogenesis.