Aggregated amyloid beta (Aβ) is widely reported to cause neuronal dystrophy and toxicity through multiple pathways: oxidative stress, disrupting calcium homeostasis, and cytoskeletal dysregulation. The neuro-cytoskeleton is a dynamic structure that reorganizes to maintain cell homeostasis in response to varying soluble and physical cues presented from the extracellular matrix (ECM). Due this relationship between cell health and the ECM, we hypothesize that amyloid toxicity may be directly influenced by physical changes to the ECM (stiffness and dimensionality) through mechanosensitive pathways, and while previous studies demonstrated that Aβ can distort focal adhesion signaling with pathological consequences, these studies do not address the physical contribution from a physiologically relevant matrix. To test our hypothesis that physical cues can adjust Aβ toxicity, SH-SY5Y human neuroblastoma and primary human cortical neurons were plated on soft and stiff, 2D polyacrylamide matrices or suspended in 3D collagen gels. Each cell culture was exposed to escalating concentrations of oligomeric or fibrillated Aβ(1-42) with MTS viability and lactate dehydrogenase toxicity assessed. Actin restructuring was further monitored in live cells by atomic force microscopy nanoindentation, and our results demonstrate that increasing either matrix stiffness or exposure to oligomeric Aβ promotes F-actin polymerization and cell stiffening, while mature Aβ fibrils yielded no apparent cell stiffening and minor toxicity. Moreover, the rounded, softer mechanical phenotype displayed by cells plated onto a compliant matrix also demonstrated a resilience to oligomeric Aβ as noted by a significant recovery of viability when compared to same-dosed cells plated on traditional tissue culture plastic. This recovery was reproduced pharmacologically through inhibiting actin polymerization with cytochalasin D prior to Aβ exposure. These studies indicate that the cell-ECM interface can modify amyloid toxicity in neurons and the matrix-mediated pathways that promote this protection may offer unique targets in amyloid pathologies like Alzheimer's disease.

中文翻译：

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SH-SY5Y神经母细胞瘤和原代人神经元的软机械表型可抵抗寡聚Aβ（1-42）损伤。

据广泛报道，聚集的淀粉样蛋白β（Aβ）通过多种途径引起神经营养不良和毒性：氧化应激，破坏钙稳态和细胞骨架失调。神经细胞骨架是一种动态结构，可对细胞外基质（ECM）呈现的各种可溶性和物理信号进行重组，以维持细胞稳态。由于细胞健康与ECM之间存在这种关系，我们假设淀粉样蛋白毒性可能直接受到机械敏感途径对ECM的物理变化（硬度和尺寸）的影响，而先前的研究表明Aβ可以使粘着斑信号转导，并带来病理后果，这些研究没有解决生理相关基质的物理作用。为了检验我们的假设，即物理提示可以调节Aβ毒性，将SH-SY5Y人成神经细胞瘤和原代人皮层神经元分别铺在柔软而坚硬的2D聚丙烯酰胺基质上，或悬浮在3D胶原凝胶中。将每种细胞培养物暴露于逐渐升高的寡聚或原纤维化Aβ（1-42）浓度，并评估其MTS活力和乳酸脱氢酶毒性。通过原子力显微镜纳米压痕进一步监测活细胞中的肌动蛋白重组，我们的结果表明增加基质刚度或暴露于寡聚Aβ均可促进F-肌动蛋白聚合和细胞硬化，而成熟的Aβ原纤维则没有明显的细胞硬化和较小的毒性。而且，四舍五入 接种于顺应性基质上的细胞所表现出的较柔和的机械表型也表现出对寡聚Aβ的适应力，与接种于传统组织培养塑料上的相同剂量细胞相比，其活力显着恢复。通过在暴露于Aβ之前用细胞松弛素D抑制肌动蛋白聚合，可以从药理学上恢复这种回收率。这些研究表明，细胞-ECM界面可以改变神经元中的淀粉样蛋白毒性，而促进这种保护作用的基质介导的途径可能在淀粉样蛋白病（如阿尔茨海默氏病）中提供独特的靶标。通过在暴露于Aβ之前用细胞松弛素D抑制肌动蛋白聚合，可以从药理学上恢复这种回收率。这些研究表明，细胞-ECM界面可以改变神经元中的淀粉样蛋白毒性，而促进这种保护作用的基质介导的途径可能在淀粉样蛋白病（如阿尔茨海默氏病）中提供独特的靶标。通过在暴露于Aβ之前用细胞松弛素D抑制肌动蛋白聚合，可以从药理学上恢复这种回收率。这些研究表明，细胞-ECM界面可以改变神经元中的淀粉样蛋白毒性，而促进这种保护作用的基质介导的途径可能在淀粉样蛋白病（如阿尔茨海默氏病）中提供独特的靶标。