Oxidation of cysteine-proteases in Alzheimer's Disease

描述(申请人提供)：阿尔茨海默病是影响全球近1800万人的痴呆症最常见的原因，预计在未来20年内将翻一番。如果没有新的重大预防或治疗措施，这一日益严重的问题将在经济和精神压力方面给社会带来巨大负担。先前的研究表明，硫醇蛋白水解酶的过度激活与AD的进展有关。这主要是基于观察到阿尔茨海默病大脑中各种硫醇蛋白水解酶的激活状态增加。然而，其他数据表明，硫醇蛋白水解酶并不是完全有活性的，抑制硫醇蛋白水解酶更有可能导致AD的病理。因此，在阿尔茨海默病中观察到的硫醇蛋白水解酶的激活和它们的蛋白分解活性之间存在着重要的差异。这些关于硫醇蛋白水解酶的激活1和硫醇蛋白水解酶的活性的相互矛盾的发现需要得到解决，以便进一步研究和确定在阿尔茨海默病期间，硫醇蛋白水解酶在tau和Abeta积累以及细胞死亡/功能障碍中的作用。为了解决我们知识中的这一差距，我们将测试一种假设，即阿尔茨海默病患者海马体中的特定氧化剂在其活性部位的半胱氨酸被氧化抑制，这一假设被激活的硫醇蛋白水解酶所抑制。目的1：测定阿尔茨海默病患者脑组织中硫醇依赖的蛋白水解酶的活性，并与年龄匹配的对照组比较，比较脆弱的海马区和非脆弱的小脑。根据我们最近发表的工作，我们将证明与年龄匹配的对照组相比，AD大脑的海马区的硫醇蛋白水解酶活性，包括钙依赖的硫醇蛋白水解酶活性，受到氧化抑制。由于AD的退化是进行性的，我们还将使用阿尔茨海默病不同阶段的大脑样本来确定疾病进展过程中硫醇蛋白水解酶氧化的程度。目的2：确定阿尔茨海默病(AD)大鼠海马区硫醇蛋白水解酶氧化的氧化剂。这些研究将确定AD海马区中单个硫醇依赖蛋白酶体内活性部位半胱氨酸氧化的氧化程度和氧化剂。这一假说挑战了现有的研究范式，提出阿尔茨海默病患者的硫醇蛋白水解酶活性由于活性部位的氧化而降低(而不是增加)。这项拟议的研究将对未来治疗或预防阿尔茨海默病的抗氧化剂或蛋白水解酶抑制剂策略产生影响。

DESCRIPTION (provided by applicant): Alzheimer's disease is the most common cause of dementia affecting nearly 18 million people worldwide and projected to double over the next 20 years. Without new and significant preventative or curative measures this growing problem will place a substantial burden on society in terms of both financial and emotional strains. Previous research has implicated over activation of thiol-proteases in AD progression. This is based primarily on the observation of an increased 'activation' state of various thiol-proteases in AD brain. However, other data suggest that thiol-proteases are not fully proteolytically active and that inhibition of thiol-proteases is more likely to contribute to AD pathology. Thus, there is an important discrepancy between the observed activation of thiol-proteases and their proteolytic activity in Alzheimer's disease. These contradictory findings regarding thiol-protease 'activation1 and thiol-protease 'activity' need to be resolved in order to move forward and determine the role of thiol-proteases in tau and Abeta accumulation as well as cell death/ dysfunction during Alzheimer's disease. To address this gap in our knowledge we will test the hypothesis that the 'activated' thiol-proteases are oxidatively inhibited at their active-site cysteines by specific oxidants in the hippocampus of Alzheimer's disease. Aim 1: Determine the activity of thiol-dependent proteases in Alzheimer's disease brain compared to age-matched controls within the vulnerable hippocampus and the non-vulnerable cerebellum. Based on our recently published work, we will show that thiol-protease activity, including calcium-dependent thiol-protease activity, is oxidatively inhibited in the hippocampus of AD brain compared to age-matched controls. Because AD degeneration is progressive, we will also determine the extent of thiol-protease oxidation over the progression of the disease using brain samples from various stages of Alzheimer's disease. Aim 2: Determine the oxidants responsible for thiol-protease oxidation in the hippocampus of AD brain. These studies will determine the extent of oxidation and the oxidants responsible for oxidation of active-site cysteines within individual thiol- dependent proteases in AD hippocampus. This hypothesis challenges an existing paradigm by suggesting thiol-protease activity in Alzheimer's disease is decreased (rather than increased) due to oxidation of the active site. The proposed research will have impact on future therapeutics involving anti-oxidant or protease inhibitor strategies in the treatment or prevention of Alzheimer's disease.