A Promising Antiprion Trimethoxychalcone Binds to the Globular Domain of the Cellular Prion Protein and Changes Its Cellular Location

Abstract

The search for antiprion compounds has been encouraged by the fact that transmissible spongiform encephalopathies (TSEs) share molecular mechanisms with more prevalent neurodegenerative pathologies, such as Parkinson's and Alzheimer's diseases. Cellular prion protein (PrP) conversion into protease-resistant forms (protease-resistant PrP [PrP] or the scrapie form of PrP [PrP]) is a critical step in the development of TSEs and is thus one of the main targets in the screening for antiprion compounds. In this work, three trimethoxychalcones (compounds J1, J8, and J20) and one oxadiazole (compound Y17), previously identified to be potential antiprion compounds, were evaluated through different approaches in order to gain inferences about their mechanisms of action. None of them changed PrP mRNA levels in N2a cells, as shown by reverse transcription-quantitative real-time PCR. Among them, J8 and Y17 were effective in real-time quaking-induced conversion reactions using rodent recombinant PrP (rPrP) from residues 23 to 231 (rPrP) as the substrate and PrP seeds from hamster and human brain. However, when rPrP from residues 90 to 231 (rPrP), which lacks the N-terminal domain, was used as the substrate, only J8 remained effective, indicating that this region is important for Y17 activity, while J8 seems to interact with the PrP globular domain. J8 also reduced the fibrillation of mouse rPrP seeded with -produced fibrils. Furthermore, most of the compounds decreased the amount of PrP on the N2a cell surface by trapping this protein in the endoplasmic reticulum. On the basis of these results, we hypothesize that J8, a nontoxic compound previously shown to be a promising antiprion agent, may act by different mechanisms, since its efficacy is attributable not only to PrP conversion inhibition but also to a reduction of the PrP content on the cell surface.

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

“…; Ferreira et al . ). Thus, we used RT‐QuIC to assess the inhibitory effect of CEs on CWD prion seeding activity (Fig.…”

“…In order to determine whether CEs exert anti-prion effects against CWD prions, we first tested CEs in prion conversion assays in vitro. RT-QuIC has been used to assess the antiprion effects of numerous drugs, whether as a screening tool to discriminate various compounds or as an assay to analyze the specific effect of a given compound (Ferreira et al 2014;Vieira et al 2014;Schmitz et al 2016;Hyeon et al 2017;Ferreira et al 2018). Thus, we used RT-QuIC to assess the inhibitory effect of CEs on CWD prion seeding activity ( Fig.…”

Multimodal small-molecule screening for human prion protein binders

“…The development of phenotypic screening for antagonists of misfolded PrP accumulation in cultured cells 22 enabled the identification of several compounds effective in vivo [23][24][25][26] , but advancement of these compounds has been hindered by lack of activity against human prion strains and unclear mechanisms of action [26][27][28][29] . Meanwhile, several compounds shown to interact with PrP through biophysical assays have demonstrated antiprion activity in a range of experimental systems [30][31][32][33][34] . However, these compounds likewise appear to lack clinical promise as none are simultaneously specific 35 , potent, and drug-like.…”

Natural and Synthetic Derivatives of Hydroxycinnamic Acid Modulating the Pathological Transformation of Amyloidogenic Proteins

“…The majority of anti-prion compounds, including polyphenols, bind precisely to this partially hydrophobic cavity surrounded by polar and charged residues. For example, according to docking and in some cases experimental confirmation, it is the binding site of curcumin and other HCA derivatives [ 119 , 120 ], chalcone derivatives [ 121 , 122 ], and other polyphenolic compounds. This was additionally confirmed by the effectiveness of the anti-prion activity of the compounds selected in this work by virtual screening.…”