Arrand J E, Squires S, Bone N M, Johnson R T
Department of Zoology, University of Cambridge, UK.
EMBO J. 1987 Oct;6(10):3125-31. doi: 10.1002/j.1460-2075.1987.tb02622.x.
The heritable DNA repair defect in human Xeroderma D cells, which results in failure to incise at u.v. light-induced pyrimidine dimers, has been partially but stably corrected by transfection of immortalised cells with the denV pyrimidine dimer glycosylase gene of bacteriophage T4. Transfectants selected either for a dominant marker on the mammalian vector carrying the prokaryotic gene or for the dominant marker plus resistance to killing by u.v. light, have been shown to express the denV gene to varying degrees. denV expression results in significant phenotypic change in the initially repair-deficient, u.v.-hypersensitive cells. Increased resistance to u.v. light and more rapid recovery of replicative DNA synthesis following u.v. irradiation have been correlated both with improved repair DNA synthesis and with a novel dimer incision capability present in denV transfected Xeroderma cells but not as evident in transfected normal cells. Most of the transfectants contain a single integrated copy of the denV gene; increase in denV copy number does not result in either increased gene expression or enhanced survival to u.v. light. These results show that expression of a heterologous prokaryotic repair gene can partially compensate for the genetic defect in a human Xeroderma D cell.
人类着色性干皮病D型细胞中的遗传性DNA修复缺陷，导致无法切割紫外线诱导的嘧啶二聚体，通过用噬菌体T4的denV嘧啶二聚体糖基化酶基因转染永生化细胞，已得到部分但稳定的纠正。选择携带原核基因的哺乳动物载体上的显性标记或显性标记加上对紫外线杀伤的抗性筛选出的转染子，已被证明能不同程度地表达denV基因。denV表达导致最初修复缺陷、紫外线敏感细胞出现显著的表型变化。对紫外线的抗性增加以及紫外线照射后复制性DNA合成的更快恢复，都与修复DNA合成的改善以及denV转染的着色性干皮病细胞中存在的一种新的二聚体切割能力相关，但在转染的正常细胞中不明显。大多数转染子含有denV基因的单个整合拷贝；denV拷贝数的增加既不会导致基因表达增加，也不会提高对紫外线的存活率。这些结果表明，异源原核修复基因的表达可以部分补偿人类着色性干皮病D型细胞中的遗传缺陷。
