Although an effective therapy for prion disease has not yet been established, many advances have been made toward understanding its pathogenesis, which has facilitated research into therapeutics for ...the disease. Several compounds, including flupirtine, quinacrine, pentosan polysulfate, and doxycycline, have recently been used on a trial basis for patients with prion disease. Concomitantly, several lead antiprion compounds, including compound B (compB), IND series, and anle138b, have been discovered. However, clinical trials are still far from yielding significantly beneficial results, and the findings of lead compound studies in animals have highlighted new challenges. These efforts have highlighted areas that need improvement or further exploration to achieve more effective therapies. In this work, we review recent advances in prion-related therapeutic research and discuss basic scientific issues to be resolved for meaningful medical intervention of prion disease.
In this study, the effects of side-chain configurations of D-Ile residues of a retro-inverso (RI)-type inhibitor on the human T-cell leukemia virus type 1 (HTLV-1) protease containing a ...hydroxyethylamine dipeptide isostere were clarified. Prior to evaluation using the RI-type inhibitor, the effects of side-chain configurations of Ile residues of the substrate peptide on the HTLV-1 protease were examined to estimate the influence of side-chain configurations on enzyme activity. Based on the estimation of the influence of side-chain configurations on protease affinity, the RI-type inhibitors containing a D-allo-Ile residue in the corresponding substrate sequence, instead of a D-Ile residue, were synthesized via 9-fluorenylmethoxycarbonyl-based solid-phase peptide synthesis. Refolded recombinant HTLV-1 protease (1-116, L40I) was used for the simple and short evaluation of the inhibitory activities of the synthesized RI-type inhibitors. The results clearly indicated that mimicking the whole topology, comprising both the main- and side-chain structures of the parent inhibitor, is effective for the design of potent RI-modified protease inhibitors.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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The design and evaluation of a novel decahydroisoquinolin scaffold as an inhibitor for severe acute respiratory syndrome (SARS) chymotrypsin-like protease (3CLpro) are described. ...Focusing on hydrophobic interactions at the S2 site, the decahydroisoquinolin scaffold was designed by connecting the P2 site cyclohexyl group of the substrate-based inhibitor to the main-chain at the α-nitrogen atom of the P2 position via a methylene linker. Starting from a cyclohexene enantiomer obtained by salt resolution, trans-decahydroisoquinolin derivatives were synthesized. All decahydroisoquinolin inhibitors synthesized showed moderate but clear inhibitory activities for SARS 3CLpro, which confirmed the fused ring structure of the decahydroisoquinolin functions as a novel scaffold for SARS 3CLpro inhibitor. X-ray crystallographic analyses of the SARS 3CLpro in a complex with the decahydroisoquinolin inhibitor revealed the expected interactions at the S1 and S2 sites, as well as additional interactions at the N-substituent of the inhibitor.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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Synthesis and evaluation of new scaffold phenylisoserine derivatives connected with the essential functional groups against SARS CoV 3CL protease are described. The phenylisoserine ...backbone was found by simulation on GOLD software and the structure activity relationship study of phenylisoserine derivatives gave SK80 with an IC50 value of 43μM against SARS CoV 3CL R188I mutant protease.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Two normally occurring polymorphisms of the human
PRNP
gene, methionine (M)/valine (V) at codon 129 and glutamic acid (E)/lysine (K) at codon 219, can affect the susceptibility to prion diseases. It ...has long been recognized that 129M/M homozygotes are overrepresented in sporadic Creutzfeldt–Jakob disease (CJD) patients and variant CJD patients, whereas 219E/K heterozygotes are absent in sporadic CJD patients. In addition to these pioneering findings, recent progress in experimental transmission studies and worldwide surveillance of prion diseases have identified novel relationships between the
PRNP
polymorphisms and the prion disease susceptibility. For example, although 219E/K heterozygosity confers resistance against the development of sporadic CJD, this genotype is not entirely protective against acquired forms (iatrogenic CJD and variant CJD) or genetic forms (genetic CJD and Gerstmann–Sträussler–Scheinker syndrome) of prion diseases. In addition, 129M/V heterozygotes predispose to genetic CJD caused by a pathogenic
PRNP
mutation at codon 180. These findings show that the effects of the
PRNP
polymorphisms may be more complicated than previously thought. This review aims to summarize recent advances in our knowledge about the influence of the
PRNP
polymorphisms on the prion disease susceptibility.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The design and evaluation of low molecular weight peptide-based severe acute respiratory syndrome (SARS) chymotrypsin-like protease (3CL) protease inhibitors are described. A substrate-based peptide ...aldehyde was selected as a starting compound, and optimum side-chain structures were determined, based on a comparison of inhibitory activities with Michael type inhibitors. For the efficient screening of peptide aldehydes containing a specific C-terminal residue, a new approach employing thioacetal to aldehyde conversion mediated by N-bromosuccinimide was devised. Structural optimization was carried out based on X-ray crystallographic analyses of the R188I SARS 3CL protease in a complex with each inhibitor to provide a tetrapeptide aldehyde with an IC50 value of 98 nM. The resulting compound carried no substrate sequence, except for a P3 site directed toward the outside of the protease. X-ray crystallography provided insights into the protein–ligand interactions.
Previous studies have revealed that the infectious scrapie isoform of prion protein (PrP
Sc
) harbored in the skin tissue of patients or animals with prion diseases can be amplified and detected ...through the serial protein misfolding cyclic amplification (sPMCA) or real-time quaking-induced conversion (RT-QuIC) assays. These findings suggest that skin PrP
Sc
-seeding activity may serve as a biomarker for the diagnosis of prion diseases; however, its utility as a biomarker for prion therapeutics remains largely unknown. Cellulose ethers (CEs, such as TC-5RW), widely used as food and pharmaceutical additives, have recently been shown to prolong the lifespan of prion-infected mice and hamsters. Here we report that in transgenic (Tg) mice expressing hamster cellular prion protein (PrP
C
) infected with the 263K prion, the prion-seeding activity becomes undetectable in the skin tissues of TC-5RW-treated Tg mice by both sPMCA and RT-QuIC assays, whereas such prion-seeding activity is readily detectable in the skin of untreated mice. Notably, TC-5RW exhibits an inhibitory effect on the in vitro amplification of PrP
Sc
in both skin and brain tissues by sPMCA and RT-QuIC. Moreover, we reveal that TC-5RW is able to directly decrease protease-resistant PrP
Sc
and inhibit the seeding activity of PrP
Sc
from chronic wasting disease and various human prion diseases. Our results suggest that the level of prion-seeding activity in the skin may serve as a useful biomarker for assessing the therapeutic efficacy of compounds in a clinical trial of prion diseases and that TC-5RW may have the potential for the prevention/treatment of human prion diseases.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In prion diseases, infectious pathogenic particles that are composed of abnormal prion proteins (PrPSc) accumulate in the brain. PrPSc is biochemically characterized by its protease-resistance core ...(PrPres), but its structural features have not been fully elucidated. Here, we report that primuline, a fluorescent dye with photosensitization activity, dramatically enhances UV-irradiation-induced SDS-resistant PrPSc/res oligomer formation that can be detected by immunoblot analysis of prion-infected materials. This oligomer formation occurs specifically with PrPSc/res but not with normal prion protein, and it was demonstrated using purified PrPSc/res as well as unpurified materials. The oligomer formation proceeded in both primuline-dose- and UV irradiation time-dependent manners. Treatment with urea or formic acid did not break oligomers into monomers. Neither did the presence of aromatic amino acids modify oligomer formation. Analysis with a panel of anti-prion protein antibodies showed that the antibodies against the N-terminal region of PrPres were less reactive in the dimer than the monomer. These findings suggest that the primuline-sensitized photoreaction enhances intermolecular crosslinking of PrPSc/res molecules at a hydrophobic area of the N-terminal region of PrPres. In the screening of other compounds, photoreactive compounds such as luciferin exhibited a similar but lower activity with respect to oligomer formation than primuline. The enhanced photoreaction with these compounds will be useful for evaluating the structural features of PrPSc/res, especially the interactions between PrPSc/res molecules.
•Primuline-sensitized photoreaction enhances SDS-resistant PrP oligomer formation.•Oligomer formation occurs specifically with PrPSc irrespective of sample purity.•Oligomers are apparently generated by intermolecular crosslinks of PrPSc molecules.•This photoreaction method does not affect the purification and detection of PrPSc.•The method will be useful for evaluating the structural features of PrPSc.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZRSKP
Prion diseases are fatal, progressive, neurodegenerative diseases caused by prion accumulation in the brain and lymphoreticular system. Here we report that a single subcutaneous injection of ...cellulose ethers (CEs), which are commonly used as inactive ingredients in foods and pharmaceuticals, markedly prolonged the lives of mice and hamsters intracerebrally or intraperitoneally infected with the 263K hamster prion. CEs provided sustained protection even when a single injection was given as long as one year before infection. These effects were linked with persistent residues of CEs in various tissues. More effective CEs had less macrophage uptake ratios and hydrophobic modification of CEs abolished the effectiveness. CEs were significantly effective in other prion disease animal models; however, the effects were less remarkable than those observed in the 263K prion-infected animals. The genetic background of the animal model was suggested to influence the effects of CEs. CEs did not modify prion protein expression but inhibited abnormal prion protein formation in vitro and in prion-infected cells. Although the mechanism of CEs in vivo remains to be solved, these findings suggest that they aid in elucidating disease susceptibility and preventing prion diseases.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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