Glutathione, Oxidative Stress, and Aging

描述(由申请人提供)：拟议研究的首要目标是通过确定果蝇抗氧化防御的遗传操作的影响，直接测试衰老的氧化应激假说的有效性。本研究要检验的具体假设是，谷胱甘肽(GSH)-NADPH系统的实验性增强将降低氧化应激水平，从而减缓衰老过程，而该系统效率的降低将提高氧化应激水平，加速衰老过程。GSH和NADPH提供了细胞内大部分的还原能力，并协同作用来清除各种活性氧物种(ROS)。通过转基因过表达谷氨酸-半胱氨酸连接酶亚基(GCL)和葡萄糖-6-磷酸脱氢酶(G6PH)，可以提高细胞合成GSH和NADPH的能力。这四个具体目标是：(I)确定GCL在身体不同部位和不同生命周期的不同时期表达过高和过低对衰老过程的影响。(Ii)确定葡萄糖-6-磷酸脱氢酶(G6PD)在人体不同部位和生命周期不同时期的过度和低表达对衰老过程的影响。(ILL)确定GCL和G6PD共同过表达对寿命和生理衰老模式的影响。(4)测定GCL和G6PD的高表达和低表达对GSH、GSSG、混合蛋白二硫化物、NADPH、NADP+、NADH和NAD+等组织氧化还原状态的影响。这些研究最令人信服的理由是，我们最近的发现表明，过表达GCL(催化亚单位)和G6PD可以使相对较长寿命的果蝇品系的寿命增加50%。前瞻性研究的结果将直接检验氧化应激衰老假说的预测，并表明细胞还原能力的增强是否可以显著延长果蝇的寿命。

DESCRIPTION (provided by applicant): The overarching goal of the proposed research is to directly test the validity of the oxidative stress hypothesis of aging by determining the effects of genetic manipulations of the antioxidative defenses in Drosophila melanogaster. The specific hypothesis to be tested in the present study is that experimental augmentation of the glutathione (GSH) - NADPH system would lower the level of oxidative stress thereby slowing the rate of the aging process, while a decrease in the efficiency of this system would elevate the level of oxidative stress and accelerate the aging process. GSH and NADPH provide the bulk of the reducing power in cells and act in concert to eliminate various reactive oxygen species (ROS). Enhancement of cellular ability to synthesize GSH and NADPH will be achieved by transgenic overexpression of y-glutamate-cysteine ligase subunits (GCL) and glucose-6-phosphate dehydrogenase (G6PH), respectively, in D. melanogaster. The four specific aims are: (I) Determine the effects of over and under expression of GCL in different regions of the body and at different periods of life cycle on the aging process. (II) Determine the effects of over and under expression of glucose-6-phosphate dehydrogenase (G6PD) in different regions of the body and at different periods of the life cycle on the aging process. (Ill) Determine the effects of co-overexpression of GCL and G6PD on the life span and patterns of physiological aging. (IV) Determine the effects of over and under expression of GCL and G6PD on the redox state of tissues indicated by GSH, GSSG, mixed protein disulfides, NADPH, NADP+, NADH and NAD+. The most compelling rationale for these studies is that our recent findings indicate that overexpression of GCL (catalytic subunit) and G6PD increases life span of relatively long-lived strains of flies by up to 50%. Results of the prospective studies would directly test the predictions of the oxidative stress hypothesis of aging and indicate whether augmentation of cellular reductive capacity can significantly extend the life span of flies.