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，氧化损伤的积累会导致线粒体功能障碍，导致能量学改变和细胞死亡级联反应的启动。然而，尽管经过了几十年的密集研究，对这一系列事件的支持仍是模棱两可的。由于缺乏必要的工具来测量线粒体在体内的功能，目前的方法通常集中在线粒体功能的体外测量，特别是电子传递链（ETC），使得有必要推断到生理状态。为了克服这一限制，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ATP合成与氧气消耗（P/O）耦合降低是衰老肌肉中线粒体功能障碍的重要机制。我们在目的1中通过测定体内线粒体P/O、最大ETC通量、ATP合成能力和体外ETC活性与四个年龄小鼠骨骼肌氧化损伤积累的关系来验证这一假设。在目的2中，我们使用转基因小鼠模型来测试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度表达一种抗氧化酶，以增加线粒体对氧化应激的抵抗力。Aim 3通过运动训练来增加线粒体增殖和周转，从而替代受损的线粒体，测试衰老肌肉中线粒体功能丧失的可逆性。本建议使用最先进的体内光谱学来解决围绕线粒体衰老理论的实验证据的争议。这项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他们各自领域几十年的经验——衰老生物学的George Martin和Peter Rabinovitch，定量生物能量学和体内光谱学的Kevin Conley和Martin Kushmerick。华盛顿大学在肌肉代谢和衰老生物学方面的国际认可项目使这个环境非常适合研究衰老和新陈代谢的综合研究。

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.