National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
Acta Biochim Biophys Sin (Shanghai). 2010 May 15;42(5):345-50. doi: 10.1093/abbs/gmq028.
Prion diseases are infectious and fatal neurodegenerative disorders. The cellular prion protein (PrP(C)) converting into misfolded isoform of prion protein (PrP(Sc)) is responsible for prion disease infection. Immune system plays an important role in facilitating the spread of prion infections from the periphery to the central nervous system. Macrophages were considered associated with the transportation and replication of PrP(Sc). So, understanding the PrP(C) trafficking in macrophages is important to explore the transport mechanism for PrP(Sc). Here, we isolated exosomes from the culture medium of Ana-1 macrophage cell line and investigated the PrP(C) trafficked by exosomes and the interaction of PrP(C) with Hsp70 in secreted exosomes by western blotting, immunoelectron microscopy, and co-immunoprecipitation. The results showed that the isolated vesicles from the culture medium of macrophages were characterized by exosomes and bore PrP(C). And PrP(C) bound to Hsp70 both in intracellular environment and secreted exosomes. In contrast, PrP(C) had no interaction with marker proteins of exosomes, Tag101 and Flotillin-1. These results suggested that PrP(C) present in extracellular space might be externalized through secreted exosomes from macrophages, and Hsp70 may play roles in the process of PrP(C) released via secreted exosomes.
朊病毒病是一种传染性和致命的神经退行性疾病。细胞朊蛋白（PrP(C)) 转化为朊病毒蛋白的错误折叠异构体（PrP(Sc)) 是导致朊病毒病感染的原因。免疫系统在促进朊病毒感染从外周向中枢神经系统的传播中起着重要作用。巨噬细胞被认为与 PrP(Sc) 的运输和复制有关。因此，了解巨噬细胞中 PrP(C) 的转运对于探索 PrP(Sc) 的运输机制很重要。在这里，我们从 Ana-1 巨噬细胞系的培养基中分离出外泌体，并通过 Western blot、免疫电子显微镜和共免疫沉淀研究了外泌体转运的 PrP(C) 以及分泌的外泌体中 PrP(C) 与 Hsp70 的相互作用。结果表明，从巨噬细胞培养基中分离出的囊泡具有外泌体的特征，并带有 PrP(C)。并且 PrP(C) 在内质网环境和分泌的外泌体中均与 Hsp70 结合。相比之下，PrP(C) 与外泌体的标记蛋白 Tag101 和 Flotillin-1 没有相互作用。这些结果表明，细胞外空间中的 PrP(C) 可能通过巨噬细胞分泌的外泌体向外释放，Hsp70 可能在通过分泌的外泌体释放 PrP(C)的过程中发挥作用。
