Cells adapted to high NaCl have many DNA breaks and impaired DNA repair both in cell culture and in vivo
Cells adapted to high NaCl have many DNA breaks and impaired DNA repair both in cell culture and in vivo
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DOI：
10.1073/pnas.0308463100
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发表时间：
2004-02-24
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;Cai, Q;Burg, MB
培养中的细胞急性暴露在高盐环境中会损伤DNA，并损害其修复。然而，在细胞周期停止几个小时后，细胞在高渗介质中增殖。在这里，我们表明，尽管适应细胞迅速增殖，不会发生凋亡，但它们仍然包含大量的DNA断裂，这不会引发DNA损伤反应。因此，在适应细胞中，Mre11核酸外切酶主要存在于细胞质中，而不是细胞核中，组蛋白H_2AX和Chk1不会被磷酸化，因为它们通常会对DNA损伤做出反应。此外，适应的细胞在修复受紫外线照射损伤的荧光素酶报告质粒方面也存在缺陷。另一方面，当盐浓度降低时，DNA损伤反应迅速激活。然后，Mre11进入细胞核，H_2AX和Chk1被磷酸化。活体肾内髓细胞通常暴露在不同水平的氯化钠中，但总是很高。与培养中的适应细胞一样，正常小鼠的内髓细胞显示出大量的DNA断裂。当注射利尿剂速尿降低氯化钠水平时，这些DNA断裂会迅速修复。此外，电离辐射引起的DNA断裂的修复在内髓受到抑制。组蛋白H_2AX不会被磷酸化，修复合成对全身照射的反应是无法检测到的，除非用速尿降低氯化钠。因此，无论是在细胞培养中还是在体内，尽管细胞适应高盐，但其DNA受到损伤，其修复受到抑制。
Acute exposure of cells in culture to high NaCl damages DNA and impairs its repair. However, after several hours of cell cycle arrest, cells multiply in the hypertonic medium. Here, we show that, although adapted cells proliferate rapidly and do not become apoptotic, they nevertheless contain numerous DNA breaks, which do not elicit a DNA damage response. Thus, in adapted cells, Mre11 exonuclease is mainly present in the cytoplasm, rather than nucleus, and histone H2AX and chk1 are not phosphorylated, as they normally would be in response to DNA damage. Also, the adapted cells are deficient in repair of luciferase reporter plasmids damaged by UV irradiation. On the other hand, the DNA damage response activates rapidly when the level of NaCl is reduced. Then, Mre11 moves into the nucleus, and H2AX and chk1 become phosphorylated. Renal inner medullary cells in vivo are normally exposed to a variable, but always high, level of NaCl. As with adapted cells in culture, inner medullary cells in normal mice exhibit numerous DNA breaks. These DNA breaks are rapidly repaired when the NaCl level is decreased by injection of the diuretic furosemide. Moreover, repair of DNA breaks induced by ionizing radiation is inhibited in the inner medulla. Histone H2AX does not become phosphorylated, and repair synthesis is not detectable in response to total body irradiation unless NaCl is lowered by furosemide. Thus, both in cell culture and in vivo, although cells adapt to high NaCl, their DNA is damaged and its repair is inhibited.