Linking mitochondrial variation and lifespan amongst five species of Rodentia

 描述(由申请人提供)：即使是关系密切的物种，寿命也有很大的差异，例如灵长类和啮齿类动物。尽管寿命上存在这些差异，但最近的研究主要集中在物种内的衰老病理上，主要是 在老鼠的系统里。虽然老鼠为衰老生物学提供了很多洞察力，但目前尚不清楚这种短暂的物种是否缺乏对衰老的防御，而衰老可能是在相关的长寿物种中进化出来的。许多与年龄相关的疾病都与线粒体功能障碍有关，线粒体功能障碍的衡量标准是能量生成减少，细胞成分受到结构性破坏，甚至细胞死亡。翻译后修饰(PTM)协调了许多与细胞代谢相关的途径，被认为是生物衰老的关键调节因子。高乙酰化就是这样一种修饰，它与许多影响能量代谢的线粒体损伤有关。最近，我们观察到了与sirtuin 3(SIRT3)基因敲除引起的氧化磷酸化相关的蛋白质/酶的显著超乙酰化以及通过热量限制提高SIRT3表达的途径--这两个因素都会影响蛋白质的乙酰化状态。此外，热量限制和SIRT3的表达显著增加了小鼠肌肉中电子传递系统(ETS)复合体I和II的电子通量，表明乙酰化状态在线粒体呼吸中起着关键作用。在比较物种之间的差异时，初步工作将小鼠与长寿的裸鼠进行比较，发现了ETS范围的差异，如裸鼠大脑和心脏的泄漏呼吸较低，以及复杂的IV活性，这表明线粒体新陈代谢存在内在差异。在这里，我们的目标是确定高乙酰化是否与线粒体功能障碍以及小鼠、大鼠、十三行地鼠、灰松鼠和裸鼠之间的寿命差异有关。我们将使用高分辨率呼吸测量法测量所有五个物种肌肉和肝脏中通过ETS的通量，并通过测量孤立的复杂活动来证实这些测量结果。接下来，我们将从这些样本中量化多肽乙酰化的化学计量，以确定它们是否与线粒体功能和寿命有关。这里提出的研究将阐明乙酰化在调节衰老中的进化作用，并建立潜在的靶点以及验证现有的治疗干预靶点。R03小赠款机制非常适合拟议的工作，因为它很好地与我们在小鼠模型中进行的衰老研究相结合，并利用我们最近开发的方法来确定大型蛋白质组中乙酰化的位点特定化学计量比。

 DESCRIPTION (provided by applicant): Lifespan varies dramatically among even closely related species, as exemplified within groups such as primates and rodents. Despite these disparities in lifespan, recent studies have focused on intra-specific aging pathologies, primarily within the murine system. While mice have provided much insight into aging biology, it is unclear if such a short-lived species lack defenses against senescence that may have evolved in related long- lived species. Many age-related diseases have been linked to mitochondrial dysfunction that are measured by decreased energy generation, structural damage to cellular components, and even cell death. Post translational modifications (PTMs) orchestrate many of the pathways associated with cellular metabolism, and are thought to be a key regulator in biological senescence. Hyperacetylation is one such modification that has been implicated in numerous mitochondrial impairments affecting energy metabolism. Recently, we observed significant hyperacetylation of proteins/enzymes in pathways associated with oxidative phosphorylation due to sirtuin 3 (SIRT3) knockout and elevated SIRT3 expression via caloric restriction - both factors that influence protein acetyl status. Furthermore, caloric restriction ad SIRT3 expression significantly increased electron flux through both complex I and II of the electron transport system (ETS) in muscle of mice, suggesting acetylation status plays a critical role in mitochondrial respiration. When comparing differences between species, preliminary work comparing mice to the long-lived naked mole rat revealed ETS-wide differences, such as lower leak respiration and complex IV activities in the brain and heart of naked mole rats, indicating inherent differences in mitochondrial metabolism. Here, we aim to establish whether hyperacetylation is associated with mitochondrial dysfunction and differences in lifespan between mice, rats, thirteen-lined ground squirrels, grey squirrels and naked mole rats. We will measure flux through the ETS in the muscle and liver of all five species using high-resolution respirometry and substantiate these measurements by measuring isolated complex activities. Next, we will quantify the stoichiometry of peptide acetylation from these samples to determine if they are correlated with both mitochondrial function and lifespan. The research proposed here will elucidate the evolutionary role of acetylation in regulating aging, and establish potential targets as well as validate existing targets for therapeutic interventions. The R03 small-grant mechanism is an excellent fit for the proposed work, as it nicely piggybacks with our ongoing aging studies in the murine model and takes advantage of our recently developed methods to determine site-specific stoichiometry of acetylation in a large proteome.