Misfolding and aggregation of proteins is strongly linked to several neurodegenerative diseases, but how such species bring about their cytotoxic actions remains poorly understood. Here we used specifically-designed optical reporter probes and live fluorescence imaging in primary hippocampal neurons to characterise the mechanism by which prefibrillar, oligomeric forms of the Alzheimer’s-associated peptide, Aβ42, exert their detrimental effects. We used a pH-sensitive reporter, Aβ42-CypHer, to track Aβ internalisation in real-time, demonstrating that oligomers are rapidly taken up into cells in a dynamin-dependent manner, and trafficked via the endo-lysosomal pathway resulting in accumulation in lysosomes. In contrast, a non-assembling variant of Aβ42 (vAβ42) assayed in the same way is not internalised. Tracking ovalbumin uptake into cells using CypHer or Alexa Fluor tags shows that preincubation with Aβ42 disrupts protein uptake. Our results identify a potential mechanism by which amyloidogenic aggregates impair cellular function through disruption of the endosomal–lysosomal pathway.

蛋白质的错误折叠和聚集与几种神经退行性疾病密切相关，但此类物种如何引起其细胞毒性作用仍然知之甚少。在这里，我们使用了专门设计的光学报告基因探针，并在原代海马神经元中进行了实时荧光成像，以表征阿尔茨海默氏症相关肽Aβ42的原纤维化，寡聚形式发挥其有害作用的机制。我们使用pH敏感的报告子Aβ42-CypHer实时跟踪Aβ内在化，表明寡聚体以动力蛋白依赖性方式迅速吸收到细胞中，并通过内溶酶体途径运输，导致溶酶体中积累。相反，未内化以相同方式测定的Aβ42的非组装变体（vAβ42）。使用CypHer或Alexa Fluor标签跟踪卵白蛋白摄取进入细胞的过程显示，与Aβ42的预温育会破坏蛋白质的摄取。我们的研究结果确定了淀粉样蛋白聚集体通过破坏内体-溶酶体途径破坏细胞功能的潜在机制。