Targeting Apolipoprotein E4-related Neuropathology

描述（由申请人提供）： 阿尔茨海默病（AD）是发达国家中增长最快的疾病之一。有400万美国人被诊断患有这种疾病，随着人口老龄化和预期寿命的增加，预计在未来20年内患病率将翻一番。然而，目前还没有真正有效的治疗方法来预防或甚至延缓AD的发展。已证明在AD发病机制中起主要作用的风险因素或易感基因是载脂蛋白（apo）E4的存在。ApoE 4明显增加迟发性AD的散发性和家族性形式的发生率并降低其发病年龄。在不同的人群研究中，携带至少一个apoE 4等位基因的AD患者的数量范围为50-80%（apoE 4等位基因在一般人群中约15%）。对apoE结构和功能的研究表明，apoE 4具有以结构域相互作用为特征的独特构象，即，氨基端的精氨酸61和羧基端的谷氨酸255相互作用。ApoE 3是最常见的apoE亚型，不能与结构域相互作用，具有更开放的构象。apoE 4与apoE 3不同的许多功能特性似乎受到结构域相互作用的调节。因此，推动这一提议的假设是，如果我们能够阻止apoE 4呈现其有害的结构构象，我们可能会阻止apoE 4相关的神经病理学。我们将使用荧光共振能量转移（FRET）（具体目标1），以确定小分子能够防止域相互作用的apoE 4。结合FRET分析筛选化学文库将鉴定在结构和功能上将apoE 4转化为“apoE 3样”分子的化合物。此外，我们将使用荧光释放试验来鉴定能够防止富含磷脂的膜的apoE 4去稳定化的小分子（特异性目的2）。细胞内膜的ApoE 4不稳定代表了apoE 4可能与神经病理学相关的一种机制。在化学文库筛选中使用这些测定将增加我们鉴定通过不同机制起作用以调节apoE 4构象和相关神经病理学的小分子（“命中”）的机会。最终，我们的目标将是“击中”先导化合物，这些化合物可能会产生一种预防或延缓apoE 4相关神经病理学的药物。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is one of the most rapidly growing disorders in developed countries. Four million Americans have been diagnosed with this disorder, and as the population grows older and life expectancy increases, the prevalence is expected to double in the next 20 years. Yet at the present time there are no truly effective therapeutics to prevent or even retard the development of AD. The risk factor or susceptibility gene proven to play a major role in AD pathogenesis is the presence of apolipoprotein (apo) E4. ApoE4 is clearly established to increase the occurrence and lower the age of onset of the sporadic and familial forms of late-onset AD. The number of AD patients carrying at least one apoE4 allele ranges from 50-80% in different population studies (the apoE4 allele occurs in approximately 15% of the general population). Studies of the structure and function of apoE have revealed that apoE4 possesses a unique conformation characterized by domain interaction, i.e., arginine 61 in the amino terminus and glutamic acid 255 in the carboxyl terminus interact. ApoE3, the most common apoE isoform, is incapable of domain interaction and has a more open conformation. Many functional properties of apoE4 that distinguish it from apoE3 appear to be modulated by domain interaction. Thus, the hypothesis driving this proposal is that if we could prevent apoE4 from assuming its detrimental structural conformation, we might block the apoE4-related neuropathology. We will use fluorescence resonance energy transfer (FRET) (Specific Aim 1) to identify small molecules capable of preventing domain interaction in apoE4. Screening of chemical libraries in combination with the FRET assay will identify compounds that convert apoE4 to an "apoE3 1ike" molecule structurally and functionally. In addition we will use a fluorescence-release assay to identify small molecules capable of preventing apoE4 destabilization of phospholipid-rich membranes (Specific Aim 2). ApoE4 destabilization of intracellular membranes represents one mechanism whereby apoE4 could be related to neuropathology. Use of these assays in chemical library screening will increase our chances of identifying small molecules ("hits") that act through different mechanisms to modulate apoE4 conformation and related neuropathology. Ultimately, it will be our goal to take "hits" to lead compounds that may give rise to a drug that prevents or retards apoE4-related neuropathology.