Mitochondrial function, oxidative damage, and aging

描述（由申请人提供）：衰老的线粒体理论指出，随着年龄的增长，氧化损伤的积累导致线粒体功能障碍，导致能量改变和细胞死亡级联的启动。然而，对这一系列事件的支持是模棱两可的，尽管几十年的紧张研究工作。由于缺乏必要的工具来测量体内线粒体功能，目前的方法通常集中在体外测量线粒体功能，特别是电子传递链（ETC），使得有必要外推到生理状态。为了克服这一局限性，我们开发了新的方法来直接测量体内线粒体功能。我们认为，减少耦合的ATP合成O2消耗（P/O）是一个重要的机制，线粒体功能障碍，在衰老肌肉。 我们测试这一假设的目的1，通过确定在体内线粒体P/O，最大ETC流量，ATP合成能力，并在体外ETC活动在小鼠骨骼肌中的氧化损伤的积累在四个年龄。在目标2中，我们使用转基因小鼠模型测试体内氧化损伤和线粒体功能障碍之间的机制联系，该模型在线粒体中过表达抗氧化酶，以增加线粒体对氧化应激的抵抗力。目的3测试衰老肌肉中线粒体功能丧失的可逆性，使用运动训练来增加线粒体增殖和周转，从而替换受损的线粒体。该提案使用最先进的体内光谱来解决围绕线粒体衰老理论实验证据的争议。这个指导研究计划将促进Marcinek博士作为华盛顿大学放射学系老年学研究员和初级教员的发展。该提案的导师代表了各自领域数十年的经验--乔治马丁和彼得拉宾诺维奇负责衰老生物学，凯文康利和马丁库什梅里克负责定量生物能量学和体内光谱学。华盛顿大学的肌肉代谢和衰老生物学方面的国际公认的课程使这种环境非常适合整合衰老和代谢研究的研究职业。

DESCRIPTION (provided by applicant): The mitochondrial theory of aging states that the accumulation of oxidative damage with age results in mitochondrial dysfunction, leading to altered energetics and initiation of cell death cascades. However, support for this chain of events is equivocal, despite several decades of intense research effort. Due to the lack of necessary tools to measure mitochondrial function in vivo, current approaches have typically focused on in vitro measurements of mitochondrial function, particularly the electron transport chain (ETC), making it necessary to extrapolate to the physiological state. To overcome this limitation, we have developed novel methods to directly measure mitochondrial function in vivo. We propose that reduced coupling of ATP synthesis to O2 consumption (P/O) is an important mechanism of mitochondrial dysfunction in aging muscle. We test this hypothesis in aim 1 by determining in vivo mitochondrial P/O, maximal ETC flux, capacity for ATP synthesis, and in vitro ETC activity in relation to the accumulation of oxidative damage in mouse skeletal muscle at four ages. In aim 2 we test the mechanistic link between oxidative damage and mitochondrial dysfunction in vivo using a transgenic mouse model that overexpresses an antioxidant enzyme in mitochondria to increase the resistance of mitochodnria to oxidative stress with age. Aim 3 tests the reversibility of the loss of mitochondrial function in aging muscle using exercise training to increase mitochondrial proliferation and turnover, thereby replacing damaged mitochondria. This proposal uses state of the art in vivo spectroscopy to address the controversy surrounding experimental evidence for the mitochondrial theory of aging. This mentored research plan will facilitate Dr. Marcinek's development as a gerontologic researcher and junior faculty member in the Department of Radiology at the University of Washington. The mentors for this proposal represent several decades of experience in their respective fields - George Martin and Peter Rabinovitch for the biology of aging and Kevin Conley and Martin Kushmerick for quantitative bioenergetics and in vivo spectroscopy. Internationally recognized programs in muscle metabolism and the biology of aging at the University of Washington make this environment ideally suited to a research career integrating the study of aging and metabolism.