Cofactors influence the biological properties of infectious recombinant prions

Abstract

Prion diseases are caused by a misfolding of the cellular prion protein (PrP) to a pathogenic isoform named PrP. Prions exist as strains, which are characterized by specific pathological and biochemical properties likely encoded in the three-dimensional structure of PrP. However, whether cofactors determine these different PrP conformations and how this relates to their specific biological properties is largely unknown. To understand how different cofactors modulate prion strain generation and selection, Protein Misfolding Cyclic Amplification was used to create a diversity of infectious recombinant prion strains by propagation in the presence of brain homogenate. Brain homogenate is known to contain these mentioned cofactors, whose identity is only partially known, and which facilitate conversion of PrP to PrP. We thus obtained a mix of distinguishable infectious prion strains. Subsequently, we replaced brain homogenate, by different polyanionic cofactors that were able to drive the evolution of mixed prion populations toward specific strains. Thus, our results show that a variety of infectious recombinant prions can be generated in vitro and that their specific type of conformation, i.e., the strain, is dependent on the cofactors available during the propagation process. These observations have significant implications for understanding the pathogenesis of prion diseases and their ability to replicate in different tissues and hosts. Importantly, these considerations might apply to other neurodegenerative diseases for which different conformations of misfolded proteins have been described.

Cellulose ether treatment in vivo generates chronic wasting disease prions with reduced protease resistance and delayed disease progression

“…; Fernandez‐Borges et al . ). Two of the defining characteristics of prion strains are conformational stability (Safar et al .…”

“…Besides, previous studies had clearly shown that there is a dissociation between seeding ability and infectivity (Miller et al 2011;Barron et al 2016;Alibhai et al 2016;Groveman et al 2017), which means that the observed seeding capacity, similar in different groups of mice does not necessarily reflect that their levels of infectivity are also comparable. In the past, studies had described that the addition of cofactors could change the path of recombinant prions leading to the generation of different strains with relative infectious properties (Deleault et al 2012;Fernandez-Borges et al 2018). Two of the defining characteristics of prion strains are conformational stability (Safar et al 1998) and selective neurotropism (Bruce et al 1997).…”

Dogs are resistant to prion infection, due to the presence of aspartic or glutamic acid at position 163 of their prion protein

“…The in vitro prion replication and PrP res detection of amplified samples was performed as described previously with minor modifications . Briefly, brains used for substrate were perfused using PBS + 5 mM EDTA and the blood‐depleted brains were frozen immediately until required for preparing the 10% brain homogenates (PBS + NaCl 0.15 M + 1% Triton X‐100).…”

“…The in vitro prion replication and PrP res detection of amplified samples was performed as described previously with minor modifications. 51 Briefly, brains used for substrate were perfused using PBS + 5 mM EDTA and the blood-depleted brains were frozen immediately until required for preparing the 10% brain homogenates (PBS + NaCl 0.15 M + 1% Triton X-100). Brain homogenates (50-60 μL of 10%), either unseeded or seeded with the corresponding prion isolate/strain, were loaded into 0.2-mL of PCR tubes and placed into a sonicating water bath at 37-38°C without shaking.…”

Cofactor and glycosylation preferences for in vitro prion conversion are predominantly determined by strain conformation

“…While the exact mechanism of prion replication remains unknown, cofactor molecules and PrP C glycosylation are both thought to play important roles in maintaining the biological infectivity [10][11][12][13][14][15] and strain properties of mammalian prions [16][17][18][19][20][21]. Using the serial protein misfolding cyclic amplification (sPMCA) technique [22,23], Nishina et al discovered that PrP C glycosylation preferences for prion propagation in vitro appear to be species-dependent [24].…”