Ku86 preserves chromatin integrity in cells adapted to high NaCl
Ku86 preserves chromatin integrity in cells adapted to high NaCl
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DOI：
10.1073/pnas.0504870102
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发表时间：
2005-07-26
影响因子：
11.1
通讯作者：
Burg, MB
中科院分区：
文献类型：
--
作者：
Dmitrieva, NI;Celeste, A;Burg, MB
适应高NaCl的细胞在细胞培养中和体内肾内髓中都有许多DNA断裂，但它们仍然存活，发挥功能，甚至增殖。在这里，我们表明，Ku 86是重要的维持染色体的完整性，尽管持续存在的DNA断裂。Ku异源二聚体是DNA依赖性PK（DNA-PK）的一部分，DNA依赖性PK是一种通过非同源末端连接来修复双链断裂的复合物。我们表明，Ku 86缺陷的细胞，但不是细胞缺乏DNA-PKcs（DNA-PK的催化亚基），是高NaCl表现为深刻的抑制增殖，异常有丝分裂，增加染色体碎片过敏。低等真核生物，包括土壤线虫秀丽隐杆线虫，缺乏DNA-PKcs同源物，但能够适应高NaCl。结果表明，C.与适应高NaCl的哺乳动物细胞相似，适应高NaCl的秀丽线虫有许多DNA断裂。Ku 86突变体C. elegans以及C.用cku 86 dsRNA喂养的线虫也显示出对高NaCl的超敏性，其特征在于在高NaCl中后代数量减少和世代时间延长。我们建议，Ku 86改善高NaCl诱导的DNA断裂在适应细胞的影响，通过支持对齐的DNA断裂的末端，从而保持完整的片段化染色质。
Cells adapted to high NaCl have many DNA breaks both in cell culture and in the renal inner medulla in vivo; yet they survive, function, and even proliferate. Here, we show that Ku86 is important for maintaining chromosomal integrity despite the continued presence of DNA breaks. The Ku heterodimer is part of DNA-dependent PK (DNA-PK), a complex that contributes by nonhomologous end joining to repair of double-strand breaks. We demonstrate that cells deficient in Ku86, but not cells deficient in DNA-PKcs (the catalytic subunit of DNA-PK), are hypersensitive to high NaCl as manifested by profound inhibition of proliferation, aberrant mitosis, and increased chromosomal fragmentation. Lower eukaryotes, including the soil nematode Caenorhabditis elegans, lack a DNA-PKcs homologue but are able to adapt to high NaCl. We show that cells of C. elegans adapted to high NaCl have many DNA breaks, similar to the mammalian cells adapted to high NaCl. Ku86 mutant C. elegans as well as C. elegans fed with cku86 dsRNA also display hypersensitivity to high NaCl, characterized by a reduced number of progeny and prolonged generation time in high NaCl. We propose that Ku86 ameliorates the effects of high NaCl-induced DNA breaks in adapted cells by supporting alignment of the broken ends of the DNA and thus maintaining integrity of the fragmented chromatin.