SPONTANEOUS KEARNS-SAYRE CHRONIC EXTERNAL OPHTHALMOPLEGIA PLUS SYNDROME ASSOCIATED WITH A MITOCHONDRIAL-DNA DELETION - A SLIP REPLICATION MODEL AND METABOLIC THERAPY
SPONTANEOUS KEARNS-SAYRE CHRONIC EXTERNAL OPHTHALMOPLEGIA PLUS SYNDROME ASSOCIATED WITH A MITOCHONDRIAL-DNA DELETION - A SLIP REPLICATION MODEL AND METABOLIC THERAPY
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DOI：
10.1073/pnas.86.20.7952
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发表时间：
1989-10-01
影响因子：
11.1
通讯作者：
WALLACE, DC
中科院分区：
文献类型：
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作者：
SHOFFNER, JM;LOTT, MT;WALLACE, DC
患有卡恩斯-塞尔/慢性外眼肌麻痹综合征的患者的肌肉线粒体被发现完全缺乏呼吸复合物 I 活性，并且部分缺乏复合物 IV 和 V 活性。使用辅酶 Q10 和琥珀酸盐治疗患者的呼吸功能出现临床改善，与呼吸缺陷的情况一致。对肌肉 mtDNA 的限制性酶分析显示，50% 的 mtDNA 分子中有 4.9 KB 的缺失。聚合酶链式反应分析表明，缺失存在于患者的肌肉中，但不存在于淋巴细胞或血小板中。此外，两姐妹的肌肉或血小板中不存在缺失。因此，突变可能发生在患者的体细胞中。聚合酶链式反应扩增 DNA 的直接测序显示，存在 4977 个碱基对缺失，删除了复合物 I 亚基的 4 个基因、复合物 IV 的 1 个基因、复合物 V 的 2 个基因和 tRNA 的 5 个基因，这与疾病中受影响的呼吸酶相似。在两个断点的上游均观察到 13 个碱基对的直接重复。相对于重链复制的方向，第一个重复被保留，第二个重复被删除，这表明滑动复制机制。人类线粒体DNA的序列分析揭示了许多10个碱基对或更多的直接重复，表明这种机制可以解释其他报道的缺失。我们假设 mtDNA 中直接重复的普遍存在是重链和轻链的鸟嘌呤-胞嘧啶偏倚的结果。
The muscle mitochondria of a patient with Kearns-Sayre/chronic external ophthalmoplegia plus syndrome were found to be completely deficient in respiratory complex I activity and partially deficient in complex IV and V activities. Treatment of the patient with coenzyme Q10 and succinate resulted in clinical improvement of respiratory function, consistent with the respiratory deficiencies. Restriction enzyme analysis of the muscle mtDNA revealed a 4.9-kilobase deletion in 50% of the mtDNA molecules. Polymerase chain reaction analysis demonstrated that the deletion was present in the patient''s muscle but not in her lymphocytes or platelets. Furthermore, the deletion was not present in the muscle or platelets of two sisters. Hence, the mutation probably occurred in the patient''s somatic cells. Direct sequencing of polymerase chain reaction-amplified DNA revealed a 4977-base-pair deletion removing four genes for subunits of complex I, one gene for complex IV, two genes for complex V, and five genes for tRNAs, which paralleled the respiratory enzymes affected in the disease. A 13-base-pair direct repeat was observed upstream from both breakpoints. Relative to the direction of heavy-strand replication, the first repeat was retained and the second repeat was deleted, suggesting a slip-replication mechanism. Sequence analysis of the human mtDNA revealed many direct repeats of 10 base pairs or greater, indicating that this mechanism could account for other reported deletions. We postulate that the prevalence of direct repeats in the mtDNA is a consequence of the guanine-cytosine bias of the heavy and light strands.