The Size and Stability of Infectious Prion Aggregates Fluctuate Dynamically during Cellular Uptake and Disaggregation

Abstract

Prion diseases arise when PrP Sc , an aggregated, infectious, and insoluble conformer of the normally soluble mammalian prion protein, PrP C , catalyzes the conversion of PrP C into more PrP Sc , which then accumulates in the brain leading to disease. PrP Sc is the primary, if not sole, component of the infectious prion. Despite the stability and protease insensitivity of PrP Sc aggregates, they can be degraded after cellular uptake. However, how cells disassemble and degrade PrP Sc is poorly understood. In this work, we analyzed how the protease sensitivity and size distribution of PrP Sc aggregates from two different mouse-adapted prion strains, 22L, that can persistently infect cells and 87V, that cannot, changed during cellular uptake. We show that within the first 4 h following uptake large PrP Sc aggregates from both prion strains become less resistant to digestion by proteinase K (PK) through a mechanism that is dependent upon the acidic environment of endocytic vesicles. We further show that during disassembly, PrP Sc aggregates from both strains become more resistant to PK digestion through the apparent removal of protease-sensitive PrP Sc , with PrP Sc from the 87V strain disassembled more readily than PrP Sc from the 22L strain. Taken together, our data demonstrate that the sizes and stabilities of PrP Sc from different prion strains change during cellular uptake and degradation, thereby potentially impacting the ability of prions to infect cells.

Effect of Elasticity of Silica Capsules on Cellular Uptake

“…Nanoparticles (NPs) are widely used as drug carriers, in cancer targeting therapy, in catalysis, and in bioimaging. − The delivery efficacy of NPs depends mainly on their interaction with cell membranes and uptake mechanisms . The regulation of interaction between NPs and cells is an important prerequisite for their application in disease treatment and diagnosis. − To date, extensive studies have confirmed that the physicochemical properties (e.g., size, shape, composition, and surface charge) of NPs have profound impacts on the cellular interactions and uptake processes. − Therefore, understanding the NP physicochemical properties and their impacts on cellular uptake and pathways is important for the design of optimal drug-delivery nanocarriers.…”