Zinc Regulation & Toxicity in Cellular Energy Metabolism

锌调节

• 批准号: 6945404
• 负责人: ABRAHAM M BROWN
• 金额: $ 32万
• 依托单位: WINIFRED MASTERSON BURKE MED RES INST
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6945404
• 关键词: NAD(P)H dehydrogenase; adenosine triphosphate; bioenergetics; biological signal transduction; carbohydrate metabolism; cellular respiration; clinical research; cytochrome c; dihydrolipoamide dehydrogenase; electron transport; enzyme activity; enzyme inhibitors; free radical oxygen; hydrogen peroxide; laboratory rat; liver; membrane permeability; membrane potentials; metallothionein; mitochondria; neuroregulation; neurotoxicology; oxidation reduction reaction; oxoglutarate dehydrogenase; pyridine nucleotide; superoxides; zinc

DESCRIPTION (provided by applicant): Recently a growing number of reports have attempted to link changes intracellular free Zn++ to pathological processes, particularly in the nervous system. Increased intracellular Zn++ is correlated with mitochondria dysfunction, loss of mitochondria defenses, increased production of ROS and cellular death. We have demonstrating that 1) Elevated Zn++ interferes with mitochondria energy utilization (respiration), due in part to inhibition of enzymes that play a role in carbohydrate metabolism, in particular alpha-ketoglutarate dehydrogenase. 2) Zn++ lowers mitochondria membrane potential and induces the opening of the mitochondria permeability pore, which releases Ca2+ and inhibits ATP generation. 3) Zn++ also inhibits the activity of pyridine nucleotide-dependent thiol reductases, which are critical to maintenance of mitochondria redox defenses. 4) Zn++ activates the NADH-oxidase activity of the mitochondria enzyme lipoamide dehydrogenase. This accelerates generation of superoxide (O2) and hydrogen peroxide (H2O2). 5) Zn++ induces release of mitochondria cytochrome c, which is a cytosolic propagator of apoptosis. Our hypotheses are that: Mitochondria and metallothioneins form a physiological feedback loop that utilizes Zn2+ as signal to regulate the balance of production between ATP, (ROS) and reduced thiols. Elevated intracellular Zn++ (is transported into mitochondria and) reduces cellular energy utilization directly by inhibiting enzymes involved in carbohydrate metabolism and electron transport and indirectly by interfering with mitochondrial redox balance. Excess (pathological) levels of cytosolic Zn2+ reduce mitochondria protection and destabilize mitochondria integrity (membrane permeability). Zn++ also induces mitochondria release of ROS and cytochrome c. Specifically, we will: 1) Characterize the spectrum of reactive products of the NADH-dehydrogenase activity of LADH that are stimulated by Zn++. 2) Characterize the inhibitory effect of Zn++ on thiol-redox activity at both the enzyme and mitochondrial level. 3) Establish the order of mitochondria events following exogenous addition of Zn++ in rat liver mitochondria. 4) Redox balance and other Zn++ -induced changes discovered and characterized in liver mitochondria in Aims 2 and 3 will be confirmed in rat brain mitochondria.

描述(申请人提供)：最近，越来越多的报告试图将细胞内游离锌离子的变化与病理过程联系起来，特别是在神经系统。细胞内锌离子的增加与线粒体功能障碍、线粒体防御能力丧失、ROS生成增加和细胞死亡有关。我们已经证明，1)升高的锌离子干扰线粒体的能量利用(呼吸)，部分原因是抑制了在碳水化合物代谢中起作用的酶，特别是α-酮戊二酸脱氢酶。2)锌离子降低线粒体膜电位，诱导线粒体通透性孔开放，释放钙离子，抑制三磷酸腺苷的生成。3)锌离子还抑制依赖于吡啶核苷酸的硫醇还原酶的活性，该酶是维持线粒体氧化还原防御的关键。4)锌离子激活线粒体酶硫酰胺脱氢酶的NADH-氧化酶活性。这加速了超氧化物(O2)和过氧化氢(H2O2)的产生。5)锌离子可诱导线粒体细胞色素c的释放，线粒体细胞色素c是细胞内细胞凋亡的增殖因子。 我们的假设是：线粒体和金属硫蛋白形成一个生理反馈环，利用锌离子作为信号来调节ATP(ROS)和还原硫醇之间的生产平衡。升高的细胞内锌离子(被转运到线粒体中)直接通过抑制参与碳水化合物代谢和电子传递的酶来减少细胞的能量利用，并间接地通过干扰线粒体的氧化还原平衡来减少细胞的能量利用。细胞内过量的(病理)锌离子降低了线粒体的保护作用，破坏了线粒体的完整性(膜通透性)。锌离子还能诱导线粒体释放ROS和细胞色素c。 具体地说，我们将：1)表征锌离子刺激LADH的NADH脱氢酶活性的反应产物的光谱。2)从酶和线粒体水平研究了锌离子对硫醇氧化还原活性的抑制作用。3)建立外源性添加锌离子后大鼠肝线粒体事件的顺序。4)在AIMS 2和AIMS 3中发现和表征的肝线粒体氧化还原平衡和其他锌离子诱导的改变将在大鼠脑线粒体中得到证实。