A deafness-associated mitochondrial DNA mutation altered the tRNASer(UCN) metabolism and mitochondrial function
A deafness-associated mitochondrial DNA mutation altered the tRNASer(UCN) metabolism and mitochondrial function
复制标题
与耳聋相关的线粒体 DNA 突变改变了 tRNASer（UCN）代谢和线粒体功能。
DOI：
10.1016/j.mito.2018.10.001
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发表时间：
2019-05-01
期刊：
影响因子：
4.4
通讯作者：
Guan, Min-Xin
中科院分区：
文献类型：
--
作者：
Xue, Ling;Chen, Yaru;Guan, Min-Xin
线粒体DNA（mtDNA）的突变与耳聋有关，其病理生理机制仍然知之甚少。本研究探讨了线粒体tRNA（Ser（ucN））中与肥胖相关的7505 A> G变异体的致病机制。m.7505A > G变体影响了11位高度保守的腺嘌呤（All），破坏了tRNA的DHU茎的高度保守的All-U24碱基配对（Ser（ucN）），并在PVC环中引入了与C56的三级碱基配对（G11-056）。因此，我们假设m.7505A > G变体改变了tRNA（Ser（ucN））的结构和功能。我们证明了m.7505A > G变体扰乱了tRNA（Ser（ucN））的构象和稳定性，如与野生型分子相比，突变的tRNA的解链温度和电泳迁移率增加所示。使用通过将来自中国家族的线粒体转移到线粒体DNA（mtDNA）较少的细胞中构建的胞质杂交体，我们证明了与对照胞质杂交体相比，m.7505A > G变体导致突变胞质杂交体中tRNA（Ser（ucN））的稳态水平显著降低。异常的tRNA（Ser（ucN））代谢导致突变胞质杂交体中mtDNA编码的多肽的可变减少。此外，我们证明了m.7505A > G变体降低了线粒体呼吸复合物I、III和IV的活性，显著降低了线粒体ATP水平和膜电位，并增加了突变胞质杂种中活性氧的产生。这些结果表明，m.7505A > G变体影响tRNA（Ser（ucN））的结构和功能，从而改变线粒体功能。我们的研究结果突出了对母系遗传性耳聋的病理生理学的重要见解，其表现为异常的tRNA代谢。
Mutations in mitochondrial DNA (mtDNA) have been associated with deafness and their pathophysiology remains poorly understood. In this study, we investigated the pathogenic mechanism of deafness-associated 7505A > G variant in the mitochondrial tRNA(Ser(ucN)). The m.7505A > G variant affected the highly conserved adenine at position 11 (All), disrupted the highly conserved All-U24 base-pairing of DHU stem of tRNA(Ser(ucN)) and introduced a tertiary base pairing (G11-056) with the C56 in the PVC loop. We therefore hypothesized that the m.7505A > G variant altered both structure and function of tRNA(Ser(ucN)). We demonstrated that the m.7505A > G variant perturbed the conformation and stability of tRNA(Ser(ucN)), as indicated by an increased melting temperature and electrophoretic mobility of the mutated tRNA compared with the wild type molecule. Using the cybrids constructed by transferring mitochondria from the Chinese family into mitochondrial DNA (mtDNA)-less cells, we demonstrated the m.7505A > G variant led to significantly decreased steady-state levels of tRNA(Ser(ucN)) in the mutant cybrids, as compared with those of control cybrids. The aberrant tRNA(Ser(ucN)) metabolism resulted in the variable decreases in mtDNA-encoded polypeptides in the mutant cybrids. Furthermore, we demonstrated that the m.7505A > G variant decreased the activities of mitochondrial respiratory complexes I, III and IV, markedly diminished mitochondrial ATP levels and membrane potential, and increased the production of reactive oxygen species in the mutant cybrids. These results demonstrated that the m.7505A > G variant affected both structure and function of tRNA(Ser(ucN)) and consequently altered mitochondrial function. Our findings highlighted critical insights into the pathophysiology of maternally inherited deafness, which is manifested by the aberrant tRNA metabolism.