Accumulation of point mutations in mitochondrial DNA of aging mice
Accumulation of point mutations in mitochondrial DNA of aging mice
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DOI：
10.1016/s0027-5107(03)00010-1
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发表时间：
2003-05-15
影响因子：
2.3
通讯作者：
Aidoo, A
中科院分区：
文献类型：
--
作者：
Khaidakov, M;Heflich, RH;Aidoo, A
线粒体DNA（mtDNA）存在于一个高度遗传毒性的环境中，该环境是由暴露于活性氧物质、DNA修复缺陷和聚合酶γ相对较低的保真度造成的。考虑到环境的严重性，人们预计，衰老动物mtDNA中的突变积累应该超过核基因几个数量级。我们分析了从2至22个月大的小鼠mtDNA的D-环区域扩增的片段。将扩增的432 bp片段克隆到质粒载体中，纯化来自各个克隆的质粒DNA并测序。来自年轻小鼠的110个片段中没有一个含有突变，而来自老年动物的87个克隆中有9个含有碱基替换（卡方= 11.9，P < 0.001）。老年小鼠mtDNA的估计突变频率为每10（5）个核苷酸11.6 +/- 2.7或25.4 +/- 7.8（取决于克隆性的假设），这超过了核基因突变频率的现有估计值约1000倍。我们的数据表明，在22个月大时，这大致相当于小鼠自然寿命的3/4，大多数mtDNA分子携带多个点突变。出版社：Elsevier Science B. V.
Mitochondrial DNA (mtDNA) exists in a highly genotoxic environment created by exposure to reactive oxygen species, somewhat deficient DNA repair, and the relatively low fidelity of polymerase gamma. Given the severity of the environment, it was anticipated that mutation accumulation in the mtDNA of aging animals should exceed that of nuclear genes by several orders of magnitude. We have analyzed fragments amplified from the D-loop region of mtDNA from 2 to 22-month-old mice. The amplified 432 bp fragments were cloned into plasmid vectors, and plasmid DNAs from individual clones were purified and sequenced. None of 110 fragments from young mice contained a mutation, while 9 of 87 clones originating from old animals contained base substitutions (chi square = 11.9, P < 0.001). The estimated mutation frequency in mtDNA from old mice was 11.6 +/- 2.7 or 25.4 +/- 7.8 per 10(5) nucleotides (depending on assumptions of clonality), which exceeds existing estimates for mutation frequencies for nuclear genes by approximately 1000-fold. Our data suggest that at 22 months of age, which roughly corresponds to 3/4 of the mouse natural life span, most mtDNA molecules carry multiple point mutations. Published by Elsevier Science B.V.