Dissecting the role of mitochondrial translation defects in ageing

尽管线粒体长期以来一直被认为是衰老的肇事者，但很少有实验证据将这些变化与衰老的细胞病理直接联系起来。最近，我们通过产生mtDNA突变小鼠，在了解获得性mtDNA突变在衰老中的基本作用方面取得了相当大的进展。mtDNA突变小鼠的创建提供了第一个直接证据，证明加速mtDNA突变率可能导致过早衰老，这与线粒体功能丧失是衰老主要原因的观点一致。此外，我们已经证明，增加的mtDNA突变负荷和增加的ROS产生之间没有直接联系，反对氧化应激在衰老过程中的直接作用。我们最新的研究结果有力地表明，观察到的表型是mtDNA点突变积累的直接结果。我们提出，即使mtDNA突变小鼠随机累积点突变，这些突变也会主要对蛋白质编码基因产生有害影响。本研究计划的目的是通过在秀丽隐杆线虫和小鼠模型中增加mtDNA蛋白编码基因中的氨基酸取代量，而不会对mtDNA的维持或完整性产生额外影响，并且不会对mtDNA编码的tRNA和rRNA基因产生影响，从而进一步验证这一假设。为此，我们将使用最近描述的线粒体翻译因子GUF1，它具有线粒体蛋白质合成保真度因子的独特功能。此外，这些将是蠕虫和小鼠线粒体翻译因子的第一个敲除模型，因此将扩大我们对这一基本过程的认识。我们认为，从基础科学和医学的角度来看，建议的项目都非常重要，并将为一般的衰老过程提供新的见解。

Although mitochondria have long been anticipated as a perpetrator of ageing, there was little experi-mental evidence to link these changes directly with the cellular pathology of ageing. Recently, we have made a considerable progress in understanding basic role of acquired mtDNA mutations in ageing by generating the mtDNA mutator mice. The creation ofmtDNA-mutator mice has provided the first direct evidence that accelerating mtDNA mutationrate can result in premature ageing, consistent with the view that loss of mitochondrialfunction is a major causal factor in ageing. Furthermore, we have shown that there is no direct connection between increased mtDNA mutation load and elevated ROS production, arguing against a direct role of oxidative stress in the ageing process. Our latest results strongly argue that the observed phenotypes are a direct consequence of the accumulation of mtDNA point mutations. We propose that even though mtDNA mutator mice randomlyaccumulate point mutations, these mutations would have a deleterious impact primarily on the protein-coding genes.The aim of this research proposal is to further test this hypothesis by making, both Caenorhabditis elegans and mouse models that will have increased amount of amino acidsubstitutions in mtDNA protein coding genes without having additional effects on mtDNAmaintenance or integrity and no effect on mtDNA encoded tRNA and rRNA genes. For this, we will use a recently described mitochondrial translation factor GUF1 with a unique functionof a fidelity factor for mitochondrial protein synthesis. Moreover, these will be the first knock -out models in both worms and mice for a mitochondrial translational factor and therefore will broaden our knowledge on this fundamental process. We believe that the suggested project is of great importance from both a basic science and a medical perspective and will provide new insights into the ageing process in general.