Amyloid-beta: The Alternate Hypothesis

描述(申请人提供)：“淀粉样级联假说”假定淀粉样蛋白-ft(Aft)是疾病发病的基本驱动机制，这一假说得到了大量细胞、动物和人类研究的支持。然而，假设aft是一种继发于氧化应激的抗氧化剂，这是对与aft相关的大量体外和体内研究结果的一种同样有效的解释。从科学的角度来看，“交替的淀粉样假说”和“淀粉样级联假说”基本上不会受到任何现有数据的挑战，这从科学的角度来看是令人不安的，从临床的角度来看更是如此，因为目前的治疗努力的目标是从大脑中移除或限制AFT。我们建议的目标是进行一系列实验，对这两种假说进行批判性测试，以确定aft作为病原体或保护剂的作用。具体地说，我们建议使用可诱导的转基因细胞培养结合最先进的分子技术来检验该领域的主要假说。我们的具体目标，以新的初步数据为指导，如下：目的1)确定用BACE抑制剂以药物方式抑制AFT是否影响氧化应激的敏感性，以及这种影响是否可以通过转染Aft1-40、Aft1-42或C99来逆转(“挽救”)；目的2)确定与家族性阿尔茨海默病相关的突变是否与氧化应激的变化有关，以及AFT的产生变化是否受抗氧化剂的影响，反之亦然；目的3)确定AFT是否受细胞内氧化还原平衡的调节。拟议研究的完成将有助于确定AFT的作用，更重要的是，指导未来的治疗靶点。

DESCRIPTION (provided by applicant): The "Amyloid Cascade Hypothesis" positing amyloid-ft (Aft) as a fundamental driving mechanism in disease pathogenesis is supported by numerous cellular, animal and human studies. However, an "Alternate Amyloid Hypothesis", positing Aft as an antioxidant that occurs secondary to oxidative stress, is an equally valid explanation for the wealth of in vitro and in vivo findings related to Aft. That the "Alternate Amyloid Hypothesis" and the "Amyloid Cascade Hypothesis" are essentially unchallenged by any currently available data is troubling from a scientific perspective and more so from a clinical perspective where current therapeutic efforts are targeted at the removal or limiting of Aft from the brain. The goal of our proposal is to conduct a series of experiments that should critically test both hypotheses to determine the role of Aft as pathogen or protectant. Specifically, we propose to use inducible transfected cell cultures together with state of the art molecular techniques to test the predominant hypothesis in the field. Our Specific Aims, guided by novel preliminary data are as follows: Aim 1) Determine whether pharmacologic inhibition of Aft with BACE inhibitors affects susceptibility to oxidative stress and whether this effect can be reversed ("rescued") by transfection with Aft1-40, Aft1-42, or C99; Aim 2) Determine whether mutations associated with familial Alzheimer disease are associated with alterations in oxidative stress and whether alterations in Aft production are affected by antioxidants or, vice versa, whether oxidative stress is altered by inhibition of Aft; Aim 3) Determine whether Aft is regulated by intracellular redox balance. Completion of the proposed studies will help determine the role of Aft and, more importantly, guide future therapeutic targets.