Analysis of DNA breaks, DNA damage response, and apoptosis produced by high NaCl
Analysis of DNA breaks, DNA damage response, and apoptosis produced by high NaCl
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DOI：
10.1152/ajprenal.90424.2008
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发表时间：
2008-12-01
影响因子：
4.2
通讯作者：
Burg, Maurice B.
中科院分区：
文献类型：
--
作者：
Dmitrieva, Natalia I.;Burg, Maurice B.
我们以前曾报道，无论是在细胞培养和在体内的肾髓质，升高NaCl的DNA断裂的数量增加，持续只要NaCl保持高，但迅速修复时，NaCl降低。此外，这些断裂不会诱导DNA修复蛋白γ H2 AX或引起MRN（Mre 11，Rad 50，Nbs 1）复合物的激活。相反，其他人最近报道高NaCl确实诱导γ H2 AX和MRN复合物形成，并得出结论这些活性与DNA的修复相关（Sheen MR，Kim SW，Jung JY，Ahn JY，Rhee JG，Kwon HM，Woo SK. Am J Physiol Renal Physiol 291：F1014-F1020，2006）。本研究的目的是解决这一差距。重要的区别是，HeLa细胞，这是后来的报告的主要对象，比我们的主要对象的mIMCD 3细胞对高NaCl的耐受性低得多。mIMCD 3细胞在通过凋亡杀死HeLa细胞的NaCl水平下存活。在这里，我们证明，在两种细胞类型中，将NaCl升高到细胞存活的水平（mIMCD 3高于HeLa）增加DNA断裂而不诱导γ H2 AX或激活MRN复合物，并且只要NaCl保持升高，DNA断裂就持续存在，但是当其降低时，DNA断裂被迅速修复。重要的是，在这两种细胞类型中，进一步提高NaCl以引起细胞凋亡激活这些DNA损伤反应蛋白并极大地片段化DNA，与细胞死亡相关。我们的结论是，γ H2 AX诱导和MRN激活响应高NaCl与细胞凋亡，而不是DNA修复。
We previously reported that, both in cell culture and in the renal inner medulla in vivo, elevating NaCl increased the number of DNA breaks, which persisted as long as NaCl remained high but were rapidly repaired when NaCl was lowered. Furthermore, those breaks did not induce the DNA repair protein gamma H2AX or cause activation of the MRN (Mre11, Rad50, Nbs1) complex. In contrast, others recently reported that high NaCl does induce gamma H2AX and MRN complex formation and concluded that these activities are associated with repair of the DNA (Sheen MR, Kim SW, Jung JY, Ahn JY, Rhee JG, Kwon HM, Woo SK. Am J Physiol Renal Physiol 291: F1014-F1020, 2006). The purpose of the present studies was to resolve the disparity. The important difference is that HeLa cells, which were the main subject of the later report, are much less tolerant of high NaCl than are the mIMCD3 cells, which were our main subject. mIMCD3 cells survive levels of NaCl that kill HeLa cells by apoptosis. Here we demonstrate that in both cell types raising NaCl to a level that the cells survive (higher for mIMCD3 than HeLa) increases DNA breaks without inducing gamma H2AX or activating the MRN complex and that the DNA breaks persist as long as NaCl remains elevated, but are rapidly repaired when it is lowered. Importantly, in both cell types, raising NaCl further to cause apoptosis activates these DNA damage response proteins and greatly fragments DNA, associated with cell death. We conclude that gamma H2AX induction and MRN activation in response to high NaCl are associated with apoptosis, not DNA repair.