Aging and CR effects on the Plasma Membrane Redox System

来自我们实验室和其他实验室的数据表明，质膜氧化还原系统至少部分负责在饮食和衰老诱导的氧化应激挑战期间维持抗氧化能力。在CR期间发生的质膜氧化还原系统的上调降低了老化膜中的氧化应激水平。CR通过降低NADH水平来延长酵母的寿命，这将这种干预与质膜NADH依赖性脱氢酶联系起来。CR改变质膜中脂肪酸的组成，导致包括脂质过氧化在内的氧化损伤减少。更重要的是，质膜氧化还原活性和辅酶Q的含量随着年龄的增长而下降，通过CR提供对磷脂的保护并防止脂质过氧化反应的进展而增强。 我们正集中精力于产生转基因和敲除参与这种抗氧化系统的不同酶的动物。我们已经成功地创建了NQO 1和Cyt-b5-还原酶过表达，并获得了NQO 1和NRF 2 KO动物。我们正在进行寿命研究和短期干预，以充分表征这些新的小鼠品系。 与Placido Navas博士的实验室合作，我们已经证明了Cyt-b5-还原酶的酿酒酵母同源物NQR 1位于质膜上，当过表达时，可以延长复制和时间寿命。我们证明，NQR 1延长复制寿命在SIR 2依赖的方式，通过转移细胞向呼吸代谢和减少吡啶核苷酸池，而不改变NAD+/NADH的比例。相反，通过SIR 2独立的乙醇生产减少发生时间上的寿命延长。我们的结论是，NQR 1是一个关键的调解人的寿命延长CR通过其对酵母代谢的影响，并讨论如何这些研究结果可能表明这种蛋白质在哺乳动物的寿命延长的功能。

Data from our laboratory and others, have demonstrated that the plasma membrane redox system is, at least in part, responsible of the maintenance of the antioxidant capacity during oxidative stress challenges induced by the diet and aging. The upregulation of the plasma membrane redox system that occurs during CR decreases the levels of oxidative stress in aged membranes. CR extends life span of yeasts by decreasing NADH levels, which would connect this intervention to plasma membrane NADH-dependent dehydrogenases. CR modifies composition of fatty acid in the plasma membrane, resulting in decreased oxidative damage including lipid peroxidation. More importantly, plasma membrane redox activities and also the content of CoQ, which decline with age, are enhanced by CR providing protection to phospholipids and preventing the lipid peroxidation reaction progression. We are focusing our efforts on the generation of transgenic and knock out animals of the different dehydrogenases involved in this antioxidant system. We have successfully created NQO1 and Cyt-b5-reductase overexpressors and obtained NQO1 and NRF2 KO animals. We are setting longevity studies as well as short term interventions to fully characterize these new mouse lines. In collaboration with the laboratory of Dr. Placido Navas we have shown that the Saccharomyces cerevisiae homolog of Cyt-b5-reductase, NQR1, resides at the plasma membrane and when overexpressed extends both replicative and chronological lifespan. We demonstrated that NQR1 extends replicative lifespan in a SIR2-dependent manner by shifting cells towards respiratory metabolism and decreasing the pyridine nucleotide pool without altering the NAD+/NADH ratio. Chronological lifespan extension, in contrast, occurs via a SIR2-independent decrease in ethanol production. We conclude that NQR1 is a key mediator of lifespan extension by CR through its effects on yeast metabolism and discuss how these findings could suggest a function for this protein in lifespan extension in mammals.