A screen for molecules that inhibit formation of A-beta oligomers in yeast

描述(申请人提供)：阿尔茨海默病(AD)是一种影响大量老年人的神经疾病。它的特点是在大脑中形成斑块，主要由抗十二烷基硫酸钠的β-淀粉样肽(A-β)纤维组成。相当多的证据支持淀粉样级联假说，即A-β多肽的积累触发了AD的出现。虽然早期证据表明A-β淀粉样蛋白纤维具有神经毒性，但最近的研究指出，十二烷基硫酸钠稳定寡聚体(已在体内和体外检测到)是主要的神经毒性物种。治疗AD的一个有希望的新方法是防止这些低聚物的形成。事实上，破坏这些低聚物而不是较大的纤维似乎是谨慎的，因为抑制A-β纤维的形成可能会导致有害的低聚物物种积累，而且抑制低聚物的形成也应该防止纤维的初始形成。目前，还没有一种简单的低聚物形成分析方法，可以直接筛选此类药物。我们正在开发A-β寡聚的酵母模型系统，以提供一种有助于这种直接药物筛选的检测方法。该系统使用A-β与酵母翻译释放因子(RF)的融合。只有在融合不齐聚的情况下，RF报告程序才会激活，并允许细胞在测试介质上生长。使用这个模型系统，我们将开发一种高通量的检测方法，使我们能够筛选出抑制A-β依赖的翻译释放因子寡聚的小分子。我们的目标是创造一种测试，允许我们通过简单地选择允许或抑制在测试介质上生长的小分子来检测A-β聚集的寡聚阶段的破坏。最终，通过观察我们测试中活性分子的结构，将有可能设计出增强其阻止A-β寡聚能力的化合物，并在人类中用作治疗或预防阿尔茨海默病的药物。最后，还需要进行动物和人体试验。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is a neurological disorder that effects large numbers of elderly people. It is characterized by the formation of plaques in the brain that are largely composed of SDS resistant fibrils of beta-amyloid peptide (A-beta). A considerable body of evidence supports the amyloid cascade hypothesis that proposes that accumulation of A-beta peptide triggers the appearance of AD. While early evidence indicated that the A-beta amyloid fibrils are neuro-toxic, recent research points to the SDS stable oligomers (that have been detected both in vivo and in vitro) as the primary neuro-toxic species. One promising emerging approach for the treatment of AD is to prevent these oligomers from forming. Indeed, disruption of these oligomers rather than the larger fibrils seems prudent since inhibition of A-beta fibril formation might cause the harmful oligomer species to accumulate and since inhibiting oligomer formation should also prevent the initial formation of the fibrils. Currently there are no simple assays for oligomer formation that would allow a direct screen for such drugs. We are developing a yeast model system of A-beta oligomerization to provide an assay that will facilitate such a direct drug screen. The system employs a fusion of A-beta to the yeast translational release factor (RF). The RF reporter will only be active and allow cells to grow on test media if the fusion does not oligomerize. Using this model system, we will develop a high throughput assay that will allow us to screen for small molecules that inhibit the A-beta dependent oligomerization of the translational release factor. Our goal is to create an assay that allows us to detect disruption of the oligomerization stage of A-beta aggregation by simply selecting for small molecules that permit or inhibit growth on test media. Eventually by looking at the structure of the molecules active in our assay it will be possible to design compounds that enhance their ability to block A-beta oligomerization and to work as a drug in humans to treat or prevent Alzheimer's disease. Finally, animal and human trials would be required.