DEFECTIVE RESPIRATORY CAPACITY AND MITOCHONDRIAL PROTEIN-SYNTHESIS IN TRANSFORMANT CYBRIDS HARBORING THE TRNA(LEU(UUR)) MUTATION ASSOCIATED WITH MATERNALLY INHERITED MYOPATHY AND CARDIOMYOPATHY
DEFECTIVE RESPIRATORY CAPACITY AND MITOCHONDRIAL PROTEIN-SYNTHESIS IN TRANSFORMANT CYBRIDS HARBORING THE TRNA(LEU(UUR)) MUTATION ASSOCIATED WITH MATERNALLY INHERITED MYOPATHY AND CARDIOMYOPATHY
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DOI：
10.1172/jci117061
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发表时间：
1994-03-01
影响因子：
15.9
通讯作者：
ZEVIANI, M
中科院分区：
文献类型：
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作者：
MARIOTTI, C;TIRANTI, V;ZEVIANI, M
我们研究了与母系遗传性肌病和心肌病相关的线粒体DNA（mtDNA）异质性点突变（A -> G（3260）转换）的生理代谢效应。为了消除可能的影响，本地核基因集，我们融合成肌细胞衍生的细胞质的患者与人类肿瘤细胞系剥夺线粒体DNA（Rho（度））。通过固相微测序测量突变体G（3260）相对于野生型A（3260）的存在和量。我们观察到一个显着减少的百分比突变体mtDNA在培养系统中相比，在捐助者的肌肉活检测量，这表明存在的负选择对突变。此外，稳定的有丝分裂分离的两个mtDNA群体中观察到的19个克隆中的18个，这表明在供体的前体细胞的细胞器内和可能的细胞内同质性的存在。与含有同质野生型线粒体DNA的克隆相比，含有高比例突变线粒体DNA的克隆中与线粒体DNA相关的呼吸能力的几项指标，包括耗氧量、复合体I和复合体IV特异性活性以及乳酸产生明显异常，这可能是由于线粒体蛋白质合成受损。我们的结论是：（a）A → G（3260）突变确实是导致供体患者线粒体疾病的原因;（B）双胞体系统提供了遗传性疾病的线粒体起源的直接证据，应被用于评估mtDNA突变的致病潜力。
We studied the physiometabolic effects of a mitochondrial DNA (mtDNA) heteroplasmic point mutation, the A --> G(3260) transition associated with maternally inherited myopathy and cardiomyopathy. To eliminate the possible influence of the autochthonous nuclear gene set, we fused myoblast-derived cytoplasts of a patient with a human tumoral cell line deprived of mtDNA (Rho(degrees)). The presence and amount of the mutant G(3260) vs the wild-type A(3260) were measured by solid phase minisequencing. We observed a marked reduction of the percentage of mutant mtDNA in the culture system compared with that measured in the donor's muscle biopsy, suggesting the presence of negative selection against the mutation. Furthermore, stable mitotic segregation of the two mtDNA populations was observed in 18 of 19 transformant clones, suggesting the presence of intraorganelle and possibly intracellular homoplasmy in the precursor cells of the donor. Several indexes of mtDNA-related respiratory capacity, including oxygen consumption, complex I- and complex IV-specific activities, and lactate production, were markedly abnormal in the clones containing a high proportion of mutant mtDNA, as compared with those containing homoplasmic wild-type mtDNA, possibly because of impaired mitochondrial protein synthesis. We conclude that (a) the A --> G(3260) transition is indeed responsible for the mitochondrial disorder identified in the donor patient, and (b) transformant cybrid system gives direct evidence of the mitochondrial origin of a genetic disorder and should be adopted for the evaluation of the pathogenic potential of the mtDNA mutations.