Molecular physiological mechanisms which modulate radiation-induced mutagenicity in human.

阐明突变机制是研究癌症发生原因的重要生物学课题。我们最近观察到，在紫外线照射前用人干扰素（huifn）预培养细胞可以抑制紫外线诱导的人类细胞突变。与huifn的抑制作用相反，在癌症患者的血清中发现了增强细胞对紫外线致突变性敏感性的因子。此外，我们发现细胞突变的调节与紫外线照射后蛋白酶活性水平的增加有关。因此，蛋白酶的鉴定对于阐明导致细胞突变调节的早期信号事件是重要的。第一年，我们纯化了分子量为35 kDa的蛋白酶，并测定了其氨基酸序列。第二年，该基因被克隆并成功转染到人类细胞中。另一方面，通过RT-PCR mRNA差异显示的方法，我们还鉴定了应激源、huifn、血清因子、UV和x射线处理的细胞中诱导的基因。然后，我们成功地将选择的基因转染到人类细胞中，并建立了可用于研究突变调节分子机制的细胞。

Elucidation of mechanisms of mutation is an important biological subject for investigating the cause of cancer development. We have recently observed that UV-induced mutation in human cells was suppressed by pre-culturing cells with human interferons (HuIFNs) prior to UV irradiation. In contrast to the suppressive effects of HuIFNs, factors that enhance cell susceptibility to UV-mutagenicity have been found in serum from cancer patients. Moreover, we have found that the modulation of cell mutability was associated with increased levels of protease activity immediately after UV irradiation. Thus, the identification of the proteases is important for elucidation of early signal events which lead to the modulation of cell mutability. In the first year, we purified the protease with amolecular mass of 35 kDa and determined its amino acid sequences. In the second year, the gene was cloned and successfully transfected into human cells. On the other hand, by using the method of RT-PCR mRNA differential display we also identified genes induced in cells treated with each of stressors, HuIFNs, serum factors, UV and X-ray. Then, we succeeded in transfection of the selected genes into human cells and establishing cells useful for investigating molecular mechanism of the mutation modulation.