Two essential but distinct functions of the mammalian abasic endonuclease
Two essential but distinct functions of the mammalian abasic endonuclease
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DOI：
10.1073/pnas.0500986102
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发表时间：
2005-04-19
影响因子：
11.1
通讯作者：
Mitra, S
中科院分区：
文献类型：
--
作者：
Izumi, T;Brown, DB;Mitra, S
哺乳动物碱性核酸内切酶APE1在DNA氧化损伤修复和基因调控中具有两种不同的作用。在这里，我们表明这两种功能对细胞存活都是必不可少的。在小鼠中，APE1基因的缺失会导致胚胎死亡，目前还没有分离到无合子胚胎成纤维细胞。我们现在已经从APE1-/-小鼠胚胎中建立了无合子胚胎成纤维细胞系，该细胞系转带有“floxed”人类APE1 （hAPE1）基因。通过核微注射Cre表达去除hAPE1可在24 h内引起这些细胞的凋亡，同时注射野生型hAPE1基因可阻断这种凋亡。相比之下，突变体hAPE1等位基因缺乏DNA修复或乙酰化介导的基因调控功能，不能阻止细胞凋亡，尽管这两个突变体的结合补充了Cre诱导的APE缺陷。这些结果表明，即使在体外，APE1的独特和可分离的功能对哺乳动物细胞也是必不可少的，并提供证据表明，与酵母或大肠杆菌不同，哺乳动物细胞绝对需要APE来生存，可能是为了防止自发的DNA氧化损伤。
The mammalian abasic endonuclease, APE1, has two distinct roles in the repair of oxidative DNA damage and in gene regulation. Here we show that both functions are essential for cell survival. Deletion of the APE1 gene causes embryonic lethality in mice, and no nullizygous embryo fibroblasts have been isolated. We have now established nullizygous embryo fibroblast lines from APE1-/- mouse embryos that are transgenic with the "floxed" human APE1 (hAPE1) gene. Removal of hAPE1 by Cre expression through nuclear microinjection elicited apoptosis in these cells within 24 h, which was blocked by coinjection of the wild-type hAPE1 gene. In contrast, mutant hAPE1 alleles, lacking either the DNA repair or acetylation-mediated gene regulatory function, could not prevent apoptosis, although the combination of these two mutants complemented APE deficiency induced by Cre. These results indicate that distinct and separable functions of APE1 are both essential for mammalian cells even in vitro and provide the evidence that mammalian cells, unlike yeast or Escherichia coli, absolutely require APE for survival, presumably to protect against spontaneous oxidative DNA damage.