Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada.
Department of Biological Sciences, Université du Québec à Montréal, Montreal, QC, Canada.
Cell Rep. 2022 Jul 19;40(3):111102. doi: 10.1016/j.celrep.2022.111102.
The nervous system spread of alpha-synuclein fibrils is thought to cause Parkinson's disease (PD) and other synucleinopathies; however, the mechanisms underlying internalization and cellular spread are enigmatic. Here, we use confocal and superresolution microscopy, subcellular fractionation, and electron microscopy (EM) of immunogold-labeled α-synuclein preformed fibrils (PFFs) to demonstrate that this form of the protein undergoes rapid internalization and is targeted directly to lysosomes in as little as 2 min. Uptake of PFFs is disrupted by macropinocytic inhibitors and circumvents classical endosomal pathways. Immunogold-labeled PFFs are seen at the highly curved inward edge of membrane ruffles, in newly formed macropinosomes, in multivesicular bodies and in lysosomes. While most fibrils remain in lysosomes, a portion is transferred to neighboring naive cells along with markers of exosomes. These data indicate that PFFs use a unique internalization mechanism as a component of cell-to-cell propagation.
人们认为α-突触核蛋白原纤维在神经系统中的扩散会导致帕金森病（PD）和其他突触核蛋白病；然而，其内化和细胞扩散的机制仍不清楚。在这里，我们使用共聚焦和超分辨率显微镜、亚细胞分级分离和免疫金标记的α-突触核蛋白原纤维（PFF）的电子显微镜（EM）来证明这种形式的蛋白质可以快速内化，并且在短短 2 分钟内直接靶向溶酶体。PFF 的摄取被巨胞饮抑制剂破坏，并绕过经典的内体途径。免疫金标记的 PFF 可见于细胞膜皱襞的高度弯曲的内缘、新形成的巨胞饮体、多泡体和溶酶体中。虽然大多数原纤维仍留在溶酶体中，但一部分原纤维与外泌体的标志物一起沿着相邻的未成熟细胞转移。这些数据表明 PFF 作为细胞间传播的一部分，使用一种独特的内化机制。
