Nucleotide excision repair in rat male germ cells:: low level of repair in intact cells contrasts with high dual incision activity in vitro
Nucleotide excision repair in rat male germ cells:: low level of repair in intact cells contrasts with high dual incision activity in vitro
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DOI：
10.1093/nar/29.8.1791
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发表时间：
2001-04-15
影响因子：
14.9
通讯作者：
Mullenders, L
中科院分区：
文献类型：
--
作者：
Jansen, J;Olsen, AK;Mullenders, L
在哺乳动物生殖系中获得遗传毒素诱导的突变对基因组信息的稳定转移是有害的。在体细胞中，核苷酸切除修复（MER）是抵抗DNA损伤的诱变效应的主要途径。已经确定了两种NER亚途径，即全局基因组修复（GGR）和转录偶联修复（TCR）。与体细胞相反，关于这些途径在生殖细胞中的表达知之甚少。为了解决这个基本问题，我们研究了NER在大鼠生精细胞粗细胞悬液中，在丰富的细胞阶段和曲细精管暴露后，UV或N-乙酰氧基-2-乙酰氨基芴。令人惊讶的是，生精细胞中的修复在整个基因组中以及在指示非功能性GGR和TCR的转录活性基因中是低效的。相反，来自早/中期粗线期细胞的提取物在体外显示出与来自体细胞的提取物一样高的双重切割活性，这表明参与切割的蛋白质在减数分裂前细胞中存在并且是功能性的。双线期细胞和圆形精子细胞提取物的切割活性较低，表明切割活性的阶段依赖性表达。我们推测，螯合NER蛋白的DNA中参与突触和重组的错配区域可能是减数分裂前细胞中NER活性缺乏的基础。
The acquisition of genotoxin-induced mutations in the mammalian germline is detrimental to the stable transfer of genomic information. in somatic cells, nucleotide excision repair (MER) is a major pathway to counteract the mutagenic effects of DNA damage. Two NER subpathways have been identified, global genome repair (GGR) and transcription-coupled repair (TCR). In contrast to somatic cells, little is known regarding the expression of these pathways in germ cells. To address this basic question, we have studied NER in rat spermatogenic cells in crude cell suspension, in enriched cell stages and within seminiferous tubules after exposure to UV or N-acetoxy-2-acetylaminofluorene. Surprisingly, repair in spermatogenic cells was inefficient in the genome overall and in transcriptionally active genes indicating non-functional GGR and TCR, In contrast, extracts from early/mid pachytene cells displayed dual incision activity in vitro as high as extracts from somatic cells, demonstrating that the proteins involved in incision are present and functional in premeiotic cells, However, incision activities of extracts from diplotene cells and round spermatids were low, indicating a stage-dependent expression of incision activity. We hypothesize that sequestering of NER proteins by mispaired regions in DNA involved in synapsis and recombination may underlie the lack of NER activity in premeiotic cells.