Prion diseases are neurodegenerative disorders pathogenically linked to cellular prion protein (PrPC) misfolding into abnormal conformers (PrPSc), with PrPSc underpinning both transmission and synaptotoxicity. Although the biophysical features of PrPSc required to induce acute synaptic dysfunction remain incompletely defined, we recently reported that acutely synaptotoxic PrPSc appeared to be oligomeric. We herein provide further insights into the kinetic and requisite biophysical characteristics of acutely synaptotoxic ex vivo PrPSc derived from the brains of mice dying from M1000 prion disease. Pooled fractions of M1000 PrPSc located within the molecular weight range approximating monomeric PrP (mM1000) generated through size exclusion chromatography were found to harbor acute synaptotoxicity equivalent to preformed oligomeric fractions (oM1000). Subsequent investigation showed mM1000 corresponded to PrPSc rapidly concatenating in physiological buffer to exist as predominantly, closely associated, small oligomers. The oligomerization of PrP in mM1000 could be substantially mitigated by treatment with the antiaggregation compound epigallocatechin gallate, thereby maintaining the PrPSc as primarily nonoligomeric with completely abrogated acute synaptotoxicity; moreover, despite epigallocatechin gallate treatment, pooled oM1000 remained oligomeric and acutely synaptotoxic. A similar tendency to rapid formation of oligomers was observed for PrPC when monomeric fractions derived from size exclusion chromatography of normal brain homogenates (mNBH) were pooled, but neither mNBH nor preformed higher-order NBH complexes (oNBH) were acutely synaptotoxic. Oligomers formed from mNBH could be reduced to mainly monomers (<100 kDa) after enzymatic digestion of nucleic acids, whereas higher-order PrP assemblies derived from pooled mM1000, oM1000, and oNBH resisted such treatment. Collectively, these findings support that oligomerization of PrPSc into small multimeric assemblies appears to be a critical biophysical feature for engendering inherent acute synaptotoxicity, with preformed oligomers found in oM1000 appearing to be stable, tightly self-associated ensembles that coexist in dynamic equilibrium with mM1000, with the latter appearing capable of rapid aggregation, albeit initially forming smaller, weakly self-associated, acutely synaptotoxic oligomers.

中文翻译：

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PrPSc 寡聚化呈现动态，快速产生固有的 M1000 急性突触毒性

朊病毒病是与细胞朊病毒蛋白 (PrPC) 错误折叠成异常构象异构体 (PrPSc) 的致病性相关的神经退行性疾病，其中 PrPSc 支持传输和突触毒性。尽管诱导急性突触功能障碍所需的 PrPSc 的生物物理特征仍未完全确定，但我们最近报告说，具有急性突触毒性的 PrPSc 似乎是寡聚体。我们在此提供了对源自死于 M1000 朊病毒疾病的小鼠大脑的急性突触毒性离体 PrPSc 的动力学和必要生物物理特征的进一步见解。发现 M1000 PrPSc 的合并部分位于近似单体 PrP (mM1000) 的分子量范围内，通过尺寸排阻色谱产生，具有与预制寡聚部分 (oM1000) 等效的急性突触毒性。随后的调查显示 mM1000 对应于 PrPSc 在生理缓冲液中快速连接，主要以紧密相关的小寡聚体形式存在。通过用抗聚集化合物表没食子儿茶素没食子酸酯处理，可以显着减轻 PrP 在 mM1000 中的寡聚化，从而将 PrPSc 保持为主要的非寡聚体，并完全消除急性突触毒性；此外，尽管表没食子儿茶素没食子酸酯处理，汇集的 oM1000 仍然是寡聚的和急性突触毒性。当汇集来自正常脑匀浆 (mNBH) 的尺寸排阻色谱的单体级分时，PrPC 观察到类似的低聚物快速形成趋势，但 mNBH 和预制的高级 NBH 复合物 (onNBH) 都没有急性突触毒性。在核酸酶消化后，由 mNBH 形成的寡聚体可以减少为主要单体 (<100 kDa)，而来自混合 mM1000、oM1000 和 onNBH 的高级 PrP 组件抵抗这种处理。总的来说，这些发现支持将 PrPSc 寡聚化成小的多聚体组装似乎是产生固有急性突触毒性的关键生物物理特征，在 oM1000 中发现的预制寡聚体似乎是稳定的、紧密自我关联的集合，与 mM1000 动态平衡共存，后者似乎能够快速聚集，尽管最初形成较小的、弱自相关的、具有急性突触毒性的低聚物。oM1000 和 onNBH 抵制这种处理。总的来说，这些发现支持将 PrPSc 寡聚化成小的多聚体组装似乎是产生固有急性突触毒性的关键生物物理特征，在 oM1000 中发现的预制寡聚体似乎是稳定的、紧密自我关联的集合，与 mM1000 动态平衡共存，后者似乎能够快速聚集，尽管最初形成较小的、弱自相关的、具有急性突触毒性的低聚物。oM1000 和 onNBH 抵制这种处理。总的来说，这些发现支持将 PrPSc 寡聚化成小的多聚体组装似乎是产生固有急性突触毒性的关键生物物理特征，在 oM1000 中发现的预制寡聚体似乎是稳定的、紧密自我关联的集合，与 mM1000 动态平衡共存，后者似乎能够快速聚集，尽管最初形成较小的、弱自相关的、具有急性突触毒性的低聚物。