Rinaldy A, Bellew T, Egli E, Lloyd R S
Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, TN 37232.
Proc Natl Acad Sci U S A. 1990 Sep;87(17):6818-22. doi: 10.1073/pnas.87.17.6818.
Xeroderma pigmentosum (XP) is an autosomal recessive disease in which the major clinical manifestation is a 2,000-fold enhanced probability of developing sunlight-induced skin tumors, and the molecular basis for the disease is a defective DNA excision repair system. To clone the gene defective in XP complementation group A (XP-A), cDNA clones were isolated by a competition hybridization strategy in which the corresponding mRNAs were more abundant in cells of the obligately heterozygous parents relative to cells of the homozygous proband affected with the disease. In this report, a human genomic DNA clone that contains this cDNA was transformed into two independent homozygous XP-A cell lines, and these transformants displayed partial restoration of resistance to the killing effects of UV irradiation. The abundance of mRNA corresponding to this cDNA appears to correlate well with the observed UV cell survival. The results of unscheduled DNA synthesis after UV exposure indicate that the transformed cells are repair proficient relative to that of the control XP-A cells. However, using this same genomic DNA, transformation of an XP-F cell line did not confer any enhancement of UV survival or promote unscheduled DNA synthesis after UV exposure.
着色性干皮病（XP）是一种常染色体隐性疾病，其主要临床表现为发生阳光诱导的皮肤肿瘤的概率增加2000倍，该疾病的分子基础是DNA切除修复系统存在缺陷。为了克隆着色性干皮病A组（XP - A）中的缺陷基因，通过竞争杂交策略分离出了cDNA克隆，在该策略中，相应的mRNA在 obligately 杂合子亲本的细胞中相对于患该疾病的纯合先证者的细胞更为丰富。在本报告中，将包含此cDNA的人类基因组DNA克隆转化到两个独立的纯合XP - A细胞系中，这些转化体对紫外线照射的杀伤作用显示出部分抗性恢复。与该cDNA对应的mRNA丰度似乎与观察到的紫外线细胞存活率密切相关。紫外线照射后非预定DNA合成的结果表明，相对于对照XP - A细胞，转化细胞的修复能力良好。然而，使用相同的基因组DNA，转化XP - F细胞系并未提高紫外线存活率，也未在紫外线照射后促进非预定DNA合成。
