Collins A R, Mitchell D L, Zunino A, de Wit J, Busch D
Rowett Research Institute and University of Aberdeen, Bucksburn, United Kingdom.
Environ Mol Mutagen. 1997;29(2):152-60.
Rodent UV-sensitive mutant cell lines of complementation groups 6 and 8 are the genetic counterparts of human Cockayne syndrome CS-B and CS-A, respectively. The original mutant in this group, UV61, was described as defective in cyclobutane pyrimidine dimer removal after high doses of UV. We have examined the responses of several cell lines from group 6 to low doses of UV irradiation, and find that these mutants have wild-type capacity for DNA repair as indicated by incision, cyclobutane pyrimidine dimer, and (6-4) photoproduct removal. ERCC6, the product of the gene defective in CS-B and group 6 mutants, is implicated in the regulation of repair of actively transcribed genes in Cockayne syndrome; however, this protein clearly is not required for the processing of low levels of damage in CHO cells, which occurs remarkably efficiently, 40-50% of dimers being removed in both wild-type and group 6 mutants in 5 hours following 0.1 Jm(-2) of UV. The group 8 mutant cell line US31, on the other hand, is very deficient in repair of UV damage, showing a more extreme phenotype than is seen in the corresponding human syndrome CS-A. In both complementation groups, expression of mutations in a gene involved in regulation of DNA repair takes very different forms in human and rodent cells.
互补组6和8的啮齿动物紫外线敏感突变细胞系分别是人类科凯恩综合征CS - B和CS - A的基因对应物。该组中的原始突变体UV61被描述为在高剂量紫外线照射后环丁烷嘧啶二聚体去除存在缺陷。我们已经检测了来自互补组6的几种细胞系对低剂量紫外线照射的反应，发现这些突变体具有野生型的DNA修复能力，如切口、环丁烷嘧啶二聚体和（6 - 4）光产物去除所示。ERCC6是CS - B和互补组6突变体中缺陷基因的产物，与科凯恩综合征中活跃转录基因的修复调节有关；然而，这种蛋白质显然不是CHO细胞中低水平损伤处理所必需的，低水平损伤处理非常高效地发生，在0.1 Jm(-2)紫外线照射后5小时，野生型和互补组6突变体中40 - 50%的二聚体被去除。另一方面，互补组8的突变细胞系US31在紫外线损伤修复方面非常缺乏，表现出比相应人类综合征CS - A更极端的表型。在这两个互补组中，参与DNA修复调节的基因中的突变在人类和啮齿动物细胞中的表达形式非常不同。
