Diver W P, Woodcock D M
Molecular Science Group, Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia.
Mutagenesis. 1989 Jul;4(4):302-5. doi: 10.1093/mutage/4.4.302.
We have used a series of clonally related mammalian cell lines with different levels of DNA methylation and the known inducer of DNA mismatch repair in Escherichia coli, 2-aminopurine (2AP), to test for the presence of methylation-directed DNA repair in mammalian cells. While a number of these hypomethylated clones showed increased sensitivity to 2AP, another similarly hypomethylated clone was resistant. DNA replication and both the immediate and delayed classes of DNA methylation were strongly inhibited and to similar extents in both sensitive and resistant clones. The inclusion of deoxycytidine reversed most of the 2AP-induced inhibition of replication and methylation without reducing 2AP toxicity. While 2AP-induced DNA mismatches are repaired by a methylation-directed process in E. coli, this analogue has major secondary effects in mammalian cells unrelated to its toxicity. Genomic methylation levels are also not a determinant of resistance or sensitivity to this base analogue in mammalian cells.
我们使用了一系列具有不同DNA甲基化水平的克隆相关哺乳动物细胞系，以及大肠杆菌中已知的DNA错配修复诱导剂2-氨基嘌呤（2AP），来检测哺乳动物细胞中是否存在甲基化导向的DNA修复。虽然这些低甲基化克隆中有许多对2AP的敏感性增加，但另一个同样低甲基化的克隆却具有抗性。DNA复制以及DNA甲基化的即时和延迟类别在敏感和抗性克隆中均受到强烈抑制，且程度相似。加入脱氧胞苷可逆转大部分2AP诱导的复制和甲基化抑制，而不会降低2AP的毒性。虽然2AP诱导的DNA错配在大肠杆菌中通过甲基化导向的过程进行修复，但这种类似物在哺乳动物细胞中具有与其毒性无关的主要次要效应。基因组甲基化水平也不是哺乳动物细胞对这种碱基类似物抗性或敏感性的决定因素。
