Amyloid-beta: The Alternate Hypothesis

描述（由申请人提供）：“淀粉样蛋白级联假说”认为淀粉样蛋白（Aft）是疾病发病的基本驱动机制，这一假说得到了大量细胞、动物和人体研究的支持。然而，“交替淀粉样蛋白假说”认为Aft是氧化应激后发生的一种抗氧化剂，是对大量与Aft相关的体外和体内研究结果的同样有效的解释。从科学的角度来看，“替代淀粉样蛋白假说”和“淀粉样蛋白级联假说”基本上没有受到任何现有数据的挑战，从临床的角度来看更是如此，因为目前的治疗努力旨在从大脑中去除或限制Aft。我们建议的目标是进行一系列实验，严格检验这两种假设，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染细胞培养以及最先进的分子技术来测试该领域的主要假设。在新的初步数据的指导下，我们的具体目标如下：目的1)确定BACE抑制剂对Aft的药理学抑制是否会影响氧化应激的易感性，以及这种影响是否可以通过转染Aft1-40、Aft1-42或C99来逆转（“拯救”）；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改变有关，以及抗氧化剂是否影响Aft生成的改变，反之亦然，氧化应激是否因抑制Aft而改变；目的3)确定Aft是否受细胞内氧化还原平衡的调节。完成拟议的研究将有助于确定Aft的作用，更重要的是，指导未来的治疗目标。

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.