Mitochondrial Genetics of Aging in Drosophila

描述（由申请人提供）：衰老的主要原因被认为是线粒体中产生的活性氧（ROS）作为氧化磷酸化（OXPHOS）的副产物。增加ROS清除或减少ROS产生的操作可以延长某些系统的寿命，但不是所有系统。热量或饮食限制（CR或DR）仍然是迄今为止所研究的所有生物体中最可重复的延长寿命的干预措施。最近的研究已经确定了CR或DR、线粒体功能改变和寿命延长之间的关系。在本文中，我们提出了明确的证据，证明mtDNA单倍型1)可以延长或缩短寿命，2)改变饮食限制的延长寿命效果，3)改变胰岛素受体底物突变chico1的延长寿命效果。这些发现为核- mtdna上位定位在揭示饮食限制延长寿命的遗传机制方面提供了原理证明。这些结果导致了这样一种假设，即mtDNA中编码的基因对营养依赖性的长寿修饰至关重要。我们将利用这些mtDNA替代菌株，利用Rpd3 - Sir2和TOR通路的上位性实验来验证这一假设，这些通路在营养基础的长寿变化中发挥重要作用。这些基因结构也将被用来测试mtDNA基因型通过改变氧化损伤水平来改变寿命的一般假设。有三个特定的目标将测试这些假设：1)mtDNA基因型是否改变依赖rpd3的寿命延长？我们将检验线粒体基因改变Rpd3对寿命的影响的假设，以及Rpd3对dr的独立性。2)mtDNA基因型是否改变饮食限制对sir2依赖性的影响？我们将通过将mtDNA与不同饮食中的过表达和组织特异性表达构建体配对，来验证mtDNA基因型改变Sir2在调节DR反应中的作用。3) mtDNA基因型是否改变了TOR通路对营养感知和延长寿命的影响？我们将通过将mtDNA与这些基因的亚形态和组织特异性表达构建体配对，来验证mtDNA基因型改变TOR和Tsc2在延长寿命中的作用的假设。公共卫生相关性：这些实验将提供关于特定线粒体基因组如何与确定的核基因相互作用以决定寿命和饮食调节寿命的基本信息。由于这些相互作用在进化上是古老且高度保守的，因此对果蝇影响衰老的遗传途径的解剖将与理解人类的衰老和与年龄相关的疾病非常相关。

DESCRIPTION (provided by applicant): A primary cause of aging is thought to be reactive oxygen species (ROS) produced in mitochondria as byproducts of oxidative phosphorylation (OXPHOS). Manipulations that either increase ROS scavenging or decrease ROS production have extended longevity in some, but not all systems. Caloric or dietary restriction (CR or DR) remains the single most repeatable intervention that extends longevity in all organisms studied to date. Recent studies have identified a relationship between CR or DR, altered mitochondrial function, and extended longevity. In this proposal we present clear evidence that mtDNA haplotypes 1) can extend or shorten longevity, 2) modify the longevity-extending effects of diet restriction, 3) modify the longevity-extending effects of the insulin receptor substrate mutation chico1. These findings provide proof of principle that nuclear-mtDNA epistasis mapping is effective in uncovering genetic mechanisms of longevity extension by diet restriction. The results lead to the hypothesis that genes encoded in mtDNA are critical for the nutrient-dependent modification of longevity. We will exploit these mtDNA replacement strains to test this hypothesis using epistasis experiments with the Rpd3 - Sir2 and TOR pathways that play important roles in nutrient-based changes in longevity. These genetic constructs will also be used to test the general hypothesis that mtDNA genotype modifies longevity through changes in the level of oxidative damage. There are three specific aims that will test each of these hypotheses: 1) Does mtDNA genotype alter the Rpd3-dependent extension of longevity? We will test the hypothesis that mitochondrial genes modify the effect of Rpd3 on longevity, and Rpd3's independence from DR. 2) Does mtDNA genotype alter the Sir2-dependent effects of dietary restriction? We will test the hypothesis that mtDNA genotype modifies the role Sir2 plays in regulating the response to DR by pairing mtDNAs with over-expression and tissue specific expression constructs on different diets. 3) Does mtDNA genotype modify the TOR pathway effects on nutrient sensing and longevity extension? We will test the hypothesis that mtDNA genotype modifies the role that TOR and Tsc2 play in extending longevity by pairing mtDNAs with hypomorphic and tissue specific expression constructs of these genes. PUBLIC HEALTH RELEVANCE: These experiments will provide fundamental information on how specific mitochondrial genomes interact with defined nuclear genes to determine longevity and the dietary modulation of longevity. As these interactions are evolutionarily ancient and highly conserved, the dissection of genetic pathways affecting aging in Drosophila will be very relevant to understanding this aging and age-related diseases in humans.