Genetic mosaic analysis of a deleterious mitochondrial DNA mutation in Drosophila reveals novel aspects of mitochondrial regulation and function.
Genetic mosaic analysis of a deleterious mitochondrial DNA mutation in Drosophila reveals novel aspects of mitochondrial regulation and function.
复制标题
DOI：
10.1091/mbc.e14-11-1513
复制
发表时间：
2015-02-15
影响因子：
3.3
通讯作者：
Xu H
中科院分区：
文献类型：
--
作者：
Chen Z;Qi Y;French S;Zhang G;Covian Garcia R;Balaban R;Xu H
AOX完全拯救了影响考克斯的致命mtDNA突变。突变基因组水平保持恒定的体细胞组织沿着在异质性苍蝇的老化过程。一个遗传方案创建组织特异性异质性，否则异质性背景，并揭示了Ca 2+处理不当有助于神经变性。许多人类疾病都与线粒体DNA（mtDNA）突变有关，但异质性-突变型和野生型mtDNA的共存-使其研究复杂化。我们以前分离的温度致死的mtDNA突变果蝇，mt：CoIT 300 I，影响细胞色素c氧化酶亚基I（CoI）位点。在本研究中，我们发现，细胞色素c氧化酶（考克斯）活性的下降归因于温度依赖性的不稳定的细胞色素a血红素。一致地，同质性果蝇在29°C下的生存力通过表达特异性绕过细胞色素链的替代氧化酶而完全恢复。异质性苍蝇是完全可行的，并用于探索年龄相关的和组织特异性表型的mt：CoIT 300 I。mt：CoIT 300 I基因组的比例在体细胞组织中沿着衰老过程保持不变，表明缺乏质量控制机制来去除含有有害mtDNA突变的缺陷线粒体。使用表达一种靶向限制性内切酶的遗传方案来诱导异质性果蝇的组织特异性同质性，我们发现眼睛中的mt：CoIT 300 I同质性在29°C下引起严重的神经变性。通过改善线粒体Ca 2+摄取抑制变性，表明Ca 2+处理不当有助于mt：CoIT 300 I的发病机制。我们的研究结果为果蝇mtDNA遗传学及其在mtDNA疾病建模中的应用提供了一种新的方法。
A lethal mtDNA mutation affecting COX is fully rescued by AOX. The mutant genome level remains constant in the somatic tissues along the aging process in heteroplasmic flies. A genetic scheme creates tissue-specific heteroplasmy in otherwise heteroplasmic background and reveals that Ca2+ mishandling contributes to the neurodegeneration. Various human diseases are associated with mitochondrial DNA (mtDNA) mutations, but heteroplasmy—the coexistence of mutant and wild-type mtDNA—complicates their study. We previously isolated a temperature-lethal mtDNA mutation in Drosophila, mt:CoIT300I, which affects the cytochrome c oxidase subunit I (CoI) locus. In the present study, we found that the decrease in cytochrome c oxidase (COX) activity was ascribable to a temperature-dependent destabilization of cytochrome a heme. Consistently, the viability of homoplasmic flies at 29°C was fully restored by expressing an alternative oxidase, which specifically bypasses the cytochrome chains. Heteroplasmic flies are fully viable and were used to explore the age-related and tissue-specific phenotypes of mt:CoIT300I. The proportion of mt:CoIT300I genome remained constant in somatic tissues along the aging process, suggesting a lack of quality control mechanism to remove defective mitochondria containing a deleterious mtDNA mutation. Using a genetic scheme that expresses a mitochondrially targeted restriction enzyme to induce tissue-specific homoplasmy in heteroplasmic flies, we found that mt:CoIT300I homoplasmy in the eye caused severe neurodegeneration at 29°C. Degeneration was suppressed by improving mitochondrial Ca2+ uptake, suggesting that Ca2+ mishandling contributed to mt:CoIT300I pathogenesis. Our results demonstrate a novel approach for Drosophila mtDNA genetics and its application in modeling mtDNA diseases.