MOLECULAR BIOLOGY OF CELLULAR INJURY

几个诱导型DNA修复基因已得到很好的表征 在原核系统中;在包括哺乳动物细胞的真核生物中， 越来越多的证据表明，类似的事件可能正在发生。 最近，我们已经表明，杂交减法可以 用于富集仅由一种 特别是细胞处理，如热休克。 中国仓鼠 细胞进行紫外线照射，并从细胞合成cDNA。 这些细胞的多聚腺苷酸化（polyA）RNA。 这种"UV" cDNA是 与来自未照射细胞的polyA RNA杂交， 分离非杂交cDNA。 通过这种方法，UV- 诱导序列富集超过30倍。 与此 富集cDNA，构建cDNA文库。 50个不同 分离cDNA克隆，发现其编码 紫外线照射后转录物的诱导倍数为2~30倍。 27种不同的cDNA 克隆进行测序，只有金属硫蛋白被鉴定， GenBank数据库显示， 以前没有分离过序列。 初步 实验中，发现这些克隆中的几个与 人成纤维细胞中的UV诱导转录物。 在中国仓鼠 选择体细胞突变体以增加对DNA的敏感性 破坏者I。希克森，两个例子都增加了 在突变细胞中发现了转录降低。 这些克隆序列的功能尚不清楚，但很可能 这些转录物中的至少一部分的蛋白质产物 在细胞对紫外线损伤的反应中发挥作用。

Several inducible DNA repair genes have been well characterized in prokaryotic systems; in eukaryotes including mammalian cells, there is increasing evidence that similar events may be occurring. Recently, we have shown that hybridization subtraction can be used to enrich for sequences induced only several fold by a particular cell treatment such as heat shock. Chinese hamster cells were UV-irradiated and cDNA was synthesized from the polyadenylated (polyA) RNA of these cells. This "UV" cDNA was hybridized with polyA RNA from unirradiated cells and the nonhybridizing cDNA was isolated. With this approach, UV- induced sequences were enriched for over 30 fold. With this enriched cDNA, a cDNA library was constructed. 50 different cDNA clones were isolated which were found to code for transcripts induced 2 to 30 fold after UV. 27 different cDNA clones were sequenced and only metallothionein was identified in the GenBank database which indicates that most of these sequences have not been isolated before. In preliminary experiments, several of these clones were found to hybridize to UV-inducible transcripts in human fibroblasts. In Chinese hamster somatic cell mutants selected for increased sensitivity to DNA damaging agents by I. Hickson, several examples of both increased and decreased transcription in the mutant cells were found. The function of these cloned sequences is unknown, but it is probable that the protein products of at least some of these transcripts play a role in the cellular response to UV damage.