Departments of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America.
Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy.
PLoS Pathog. 2020 Apr 15;16(4):e1008495. doi: 10.1371/journal.ppat.1008495. eCollection 2020 Apr.
Prion diseases are caused by the misfolding of a host-encoded glycoprotein, PrPC, into a pathogenic conformer, PrPSc. Infectious prions can exist as different strains, composed of unique conformations of PrPSc that generate strain-specific biological traits, including distinctive patterns of PrPSc accumulation throughout the brain. Prion strains from different animal species display different cofactor and PrPC glycoform preferences to propagate efficiently in vitro, but it is unknown whether these molecular preferences are specified by the amino acid sequence of PrPC substrate or by the conformation of PrPSc seed. To distinguish between these two possibilities, we used bank vole PrPC to propagate both hamster or mouse prions (which have distinct cofactor and glycosylation preferences) with a single, common substrate. We performed reconstituted sPMCA reactions using either (1) phospholipid or RNA cofactor molecules, or (2) di- or un-glycosylated bank vole PrPC substrate. We found that prion strains from either species are capable of propagating efficiently using bank vole PrPC substrates when reactions contained the same PrPC glycoform or cofactor molecule preferred by the PrPSc seed in its host species. Thus, we conclude that it is the conformation of the input PrPSc seed, not the amino acid sequence of the PrPC substrate, that primarily determines species-specific cofactor and glycosylation preferences. These results support the hypothesis that strain-specific patterns of prion neurotropism are generated by selection of differentially distributed cofactors molecules and/or PrPC glycoforms during prion replication.
朊病毒病是由宿主编码的糖蛋白 PrPC 错误折叠成致病性构象 PrPSc 引起的。传染性朊病毒可以存在不同的株型，由 PrPSc 的独特构象组成，这些构象产生了株型特异性的生物学特征，包括在大脑中积累的 PrPSc 的独特模式。不同动物物种的朊病毒株在体外有效地繁殖时表现出不同的辅助因子和 PrPC 糖型偏好，但尚不清楚这些分子偏好是由 PrPC 底物的氨基酸序列还是 PrPSc 种子的构象决定的。为了区分这两种可能性，我们使用田鼠 PrPC 来繁殖仓鼠或小鼠朊病毒（它们具有不同的辅助因子和糖基化偏好），使用单一的、共同的底物。我们使用（1）磷脂或 RNA 辅助因子分子，或（2）二或未糖基化的田鼠 PrPC 底物进行了重组 sPMCA 反应。我们发现，当反应中含有与其宿主物种中 PrPSc 种子偏好的相同 PrPC 糖型或辅助因子分子时，来自任一物种的朊病毒株都能够使用田鼠 PrPC 底物有效地繁殖。因此，我们得出结论，决定物种特异性辅助因子和糖基化偏好的主要因素是输入 PrPSc 种子的构象，而不是 PrPC 底物的氨基酸序列。这些结果支持了这样一种假设，即朊病毒神经嗜性的株型特异性模式是通过在朊病毒复制过程中选择差异分布的辅助因子分子和/或 PrPC 糖型产生的。
