Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, U.K.
Biochem J. 2018 Nov 9;475(21):3417-3436. doi: 10.1042/BCJ20180715.
Deposition of misfolded amyloid polypeptides, associated with cell death, is the hallmark of many degenerative diseases (e.g. type II diabetes mellitus and Alzheimer's disease). , cellular and extracellular spaces are occupied by a high volume fraction of macromolecules. The resulting macromolecular crowding energetically affects reactions. Amyloidogenesis can either be promoted by macromolecular crowding through the excluded volume effect or inhibited due to a viscosity increase reducing kinetics. Macromolecular crowding can be mimicked by the addition of non-specific polymers, e.g. Ficoll, dextran and polyvinyl pyrrolidone (PVP), the latter being rarely used to study amyloid systems. We investigated the effect of PVP on amyloidogenesis of full-length human islet amyloid polypeptide (involved in type II diabetes) using fibrillisation and surface activity assays, ELISA, immunoblot and microscale thermophoresis. We demonstrate that high molecular mass PVP360 promotes amyloidogenesis due to volume exclusion and increase in effective amyloidogenic monomer concentration, like other crowders, but without the confounding effects of viscosity and surface activity. Interestingly, we also show that low molecular mass PVP10 has unique inhibitory properties as inhibition of fibril elongation occurs mainly in the bulk solution and is due to PVP10 directly and strongly interacting with amyloid species rather than the increase in viscosity typically associated with macromolecular crowding. , amyloidogenesis might be affected by the properties and proximity of endogenous macromolecular crowders, which could contribute to changes in associated pathogenesis. More generally, the PVP10 molecular backbone could be used to design small compounds as potential inhibitors of toxic species formation.
错误折叠的淀粉样多肽的沉积与细胞死亡有关，是许多退行性疾病（如 2 型糖尿病和阿尔茨海默病）的标志。在这些疾病中，细胞内和细胞外空间被高分子量的物质占据。这种高分子量物质的拥挤状态会在能量上影响反应。淀粉样变性可以通过高分子量物质的排挤体积效应促进，也可以因粘度增加降低动力学而抑制。通过添加非特异性聚合物，如 Ficoll、葡聚糖和聚乙烯吡咯烷酮（PVP），可以模拟高分子量物质的拥挤状态，后者很少用于研究淀粉样系统。我们使用纤维形成和表面活性测定、ELISA、免疫印迹和微尺度热泳法研究了 PVP 对全长人胰岛淀粉样多肽（与 2 型糖尿病有关）淀粉样生成的影响。我们证明高分子量 PVP360 通过体积排除和有效淀粉样单体浓度的增加促进淀粉样生成，就像其他拥挤剂一样，但没有粘度和表面活性的混杂影响。有趣的是，我们还表明低分子量 PVP10 具有独特的抑制特性，因为纤维伸长的抑制主要发生在本体溶液中，并且是由于 PVP10 直接且强烈地与淀粉样物质相互作用，而不是与高分子量拥挤通常相关的粘度增加。因此，淀粉样生成可能受到内源性高分子量拥挤物质的性质和接近性的影响，这可能导致相关发病机制的变化。更一般地说，PVP10 的分子骨架可以被用来设计小分子作为潜在的有毒物质形成抑制剂。
