Modulation of Aβ42 low-n oligomerization using a novel yeast reporter system
Modulation of Aβ42 low-n oligomerization using a novel yeast reporter system
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DOI：
10.1186/1741-7007-4-32
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发表时间：
2006-09-26
期刊：
影响因子：
5.4
通讯作者：
Liebman, Susan
中科院分区：
文献类型：
--
作者：
Bagriantsev, Sviatoslav;Liebman, Susan
背景：虽然阿尔茨海默病的传统模型主要关注大脑中A β(42)淀粉样肽的大纤维沉积，但最近的研究表明，主要的致病作用可能归因于sds稳定的A β低聚物（42）。这些A β(42)低聚物代表了治疗干预的合理目标，然而控制其组装的因素却知之甚少。结果：我们描述了一个新的酵母模型系统，专注于a β(42)寡聚的初始阶段。我们发现a β(42)与报告蛋白融合的活性在酵母中通过形成SDS-稳定的低n低聚物而受到损害。这些低聚物让人联想到A β(42)肽在体外、哺乳动物细胞培养和人脑中形成的低n低聚物。先前在体外显示抑制A β(42)聚集的点突变是在融合蛋白的A β(42)部分产生的。这些突变既抑制了寡聚化，又恢复了融合蛋白的活性。利用这个模型系统，我们发现融合蛋白的寡聚化受到毫摩尔浓度的酵母朊病毒固化剂胍的刺激。令人惊讶的是，缺失伴侣Hsp104（已知胍的靶标）抑制了融合蛋白的寡聚化。此外，我们证明Hsp104与A β(42)融合蛋白相互作用，并似乎保护其免于分解和降解。结论：先前的阿尔茨海默病模型侧重于揭示抑制A β(42)纤维化的化合物，即A β(42)组装的最后一步。然而，抑制成纤维化可能导致A β的有毒低聚物的积累（42）。这里描述的模型可用于搜索和测试蛋白质或化合物对A β(42)寡聚初始步骤的干扰能力。我们的研究结果表明，酵母含有胍敏感因子(s)，可以减少A β的低n低聚物的数量（42）。由于许多酵母蛋白具有人类同源物，鉴定这些因素可能有助于揭示影响哺乳动物A β(42)寡聚化的同源蛋白。结论：先前的阿尔茨海默病模型侧重于揭示抑制A β(42)纤维化的化合物，即A β(42)组装的最后一步。然而，抑制成纤维化可能导致A β的有毒低聚物的积累（42）。这里描述的模型可用于搜索和测试蛋白质或化合物对A β(42)寡聚初始步骤的干扰能力。我们的研究结果表明，酵母含有胍敏感因子(s)，可以减少A β的低n低聚物的数量（42）。由于许多酵母蛋白具有人类同源物，鉴定这些因素可能有助于揭示影响哺乳动物A β(42)寡聚化的同源蛋白。
Background: While traditional models of Alzheimer's disease focused on large fibrillar deposits of the A beta(42) amyloid peptide in the brain, recent work suggests that the major pathogenic effects may be attributed to SDS-stable oligomers of A beta(42). These A beta(42) oligomers represent a rational target for therapeutic intervention, yet factors governing their assembly are poorly understood.Results: We describe a new yeast model system focused on the initial stages of A beta(42) oligomerization. We show that the activity of a fusion of A beta(42) to a reporter protein is compromised in yeast by the formation of SDS- stable low-n oligomers. These oligomers are reminiscent of the low-n oligomers formed by the A beta(42) peptide in vitro, in mammalian cell culture, and in the human brain. Point mutations previously shown to inhibit A beta(42) aggregation in vitro, were made in the A beta(42) portion of the fusion protein. These mutations both inhibited oligomerization and restored activity to the fusion protein. Using this model system, we found that oligomerization of the fusion protein is stimulated by millimolar concentrations of the yeast prion curing agent guanidine. Surprisingly, deletion of the chaperone Hsp104 (a known target for guanidine) inhibited oligomerization of the fusion protein. Furthermore, we demonstrate that Hsp104 interacts with the A beta(42)-fusion protein and appears to protect it from disaggregation and degradation.Conclusion: Previous models of Alzheimer's disease focused on unravelling compounds that inhibit fibrillization of A beta(42), i.e. the last step of A beta(42) assembly. However, inhibition of fibrillization may lead to the accumulation of toxic oligomers of A beta(42). The model described here can be used to search for and test proteinacious or chemical compounds for their ability to interfere with the initial steps of A beta(42) oligomerization. Our findings suggest that yeast contain guanidine-sensitive factor(s) that reduce the amount of low-n oligomers of A beta(42). As many yeast proteins have human homologs, identification of these factors may help to uncover homologous proteins that affect A beta(42) oligomerization in mammals.Conclusion: Previous models of Alzheimer's disease focused on unravelling compounds that inhibit fibrillization of A beta(42), i.e. the last step of A beta(42) assembly. However, inhibition of fibrillization may lead to the accumulation of toxic oligomers of A beta(42). The model described here can be used to search for and test proteinacious or chemical compounds for their ability to interfere with the initial steps of A beta(42) oligomerization. Our findings suggest that yeast contain guanidine-sensitive factor(s) that reduce the amount of low-n oligomers of A beta(42). As many yeast proteins have human homologs, identification of these factors may help to uncover homologous proteins that affect A beta(42) oligomerization in mammals.