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The neuro-physiological properties of individuals with genetic pre-disposition to neurological disorders are largely unknown. Here we aimed to explore these properties using cerebral organoids (COs) derived from fibroblasts of individuals with confirmed genetic mutations including PRNPE200K, trisomy 21 (T21), and LRRK2G2019S, which are associated with Creutzfeldt Jakob disease, Down Syndrome, and Parkinson’s disease. We utilized no known disease/healthy COs (HC) as normal function controls. At 3–4 and 6–10 months post-differentiation, COs with mutations showed no evidence of disease-related pathology. Electrophysiology assessment showed that all COs exhibited mature neuronal firing at 6–10 months old. At this age, we observed significant changes in the electrophysiology of the COs with disease-associated mutations (dCOs) as compared with the HC, including reduced neuronal network communication, slowing neuronal oscillations, and increased coupling of delta and theta phases to the amplitudes of gamma oscillations. Such changes were linked with the detection of hypersynchronous events like spike-and-wave discharges. These dysfunctions were associated with altered production and release of neurotransmitters, compromised activity of excitatory ionotropic receptors including receptors of kainate, AMPA, and NMDA, and changed levels and function of excitatory glutamatergic synapses and inhibitory GABAergic synapses. Neuronal properties that modulate GABAergic inhibition including the activity of Na–K-Cl cotransport 1 (NKCC1) in Cl− homeostasis and the levels of synaptic and extra-synaptic localization of GABA receptors (GABARs) were altered in the T21 COs only. The neurosteroid allopregnanolone, a positive modulator of GABARs, was downregulated in all the dCOs. Treatment with this neurosteroid significantly improved the neuronal communication in the dCOs, possibly through improving the GABAergic inhibition. Overall, without the manifestation of any disease-related pathology, the genetic mutations PRNPE200K, T21, and LRRK2G2019S significantly altered the neuronal network communication in dCOs by disrupting the excitatory-to-inhibitory balance.

Previous studies have revealed that the infectious scrapie isoform of prion protein (PrPSc) 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 PrPSc-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 (PrPC) 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 PrPSc in both skin and brain tissues by sPMCA and RT-QuIC. Moreover, we reveal that TC-5RW is able to directly decrease protease-resistant PrPSc and inhibit the seeding activity of PrPSc 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.

The process of neuroinflammation contributes to the pathogenic mechanism of many neurodegenerative diseases. The deleterious attributes of neuroinflammation involve aberrant and uncontrolled activation of glia, which can result in damage to proximal brain parenchyma. Failure to distinguish self from non-self, as well as leukocyte reaction to aggregation and accumulation of proteins in the CNS, are the primary mechanisms by which neuroinflammation is initiated. While processes local to the CNS may instigate neurodegenerative disease, the existence or dysregulation of systemic homeostasis can also serve to improve or worsen CNS pathologies, respectively. One fundamental component of systemic homeostasis is the gut microbiota, which communicates with the CNS via microbial metabolite production, the peripheral nervous system, and regulation of tryptophan metabolism. Over the past 10–15 years, research focused on the microbiota–gut–brain axis has culminated in the discovery that dysbiosis, or an imbalance between commensal and pathogenic gut bacteria, can promote CNS pathologies. Conversely, a properly regulated and well-balanced microbiome supports CNS homeostasis and reduces the incidence and extent of pathogenic neuroinflammation. This review will discuss the role of the gut microbiota in exacerbating or alleviating neuroinflammation in neurodegenerative diseases, and potential microbiota-based therapeutic approaches to reduce pathology in diseased states.

Importance Deposition of the pathological α-synuclein (αSynP) in the brain is the hallmark of synucleinopathies, including Parkinson disease (PD), Lewy body dementia (LBD), and multiple system atrophy (MSA). Whether real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA) assays can sensitively detect skin biomarkers for PD and non-PD synucleinopathies remains unknown. Objective To develop sensitive and specific skin biomarkers for antemortem diagnosis of PD and other synucleinopathies. Design, Setting, and Participants This retrospective and prospective diagnostic study evaluated autopsy and biopsy skin samples from neuropathologically and clinically diagnosed patients with PD and controls without PD. Autopsy skin samples were obtained at 3 medical centers from August 2016 to September 2019, and biopsy samples were collected from 3 institutions from August 2018 to November 2019. Based on neuropathological and clinical diagnoses, 57 cadavers with synucleinopathies and 73 cadavers with nonsynucleinopathies as well as 20 living patients with PD and 21 living controls without PD were included. Specifically, cadavers and participants had PD, LBD, MSA, Alzheimer disease, progressive supranuclear palsy, or corticobasal degeneration or were nonneurodegenerative controls (NNCs). A total of 8 approached biopsy participants either refused to participate in or were excluded from this study due to uncertain clinical diagnosis. Data were analyzed from September 2019 to April 2020. Main Outcomes and Measures Skin αSynPseeding activity was analyzed by RT-QuIC and PMCA assays. Results A total of 160 autopsied skin specimens from 140 cadavers (85 male cadavers [60.7%]; mean [SD] age at death, 76.8 [10.1] years) and 41 antemortem skin biopsies (27 male participants [66%]; mean [SD] age at time of biopsy, 65.3 [9.2] years) were analyzed. RT-QuIC analysis of αSynPseeding activity in autopsy abdominal skin samples from 47 PD cadavers and 43 NNCs revealed 94% sensitivity (95% CI, 85-99) and 98% specificity (95% CI, 89-100). As groups, RT-QuIC also yielded 93% sensitivity (95% CI, 85-97) and 93% specificity (95% CI, 83-97) among 57 cadavers with synucleinopathies (PD, LBD, and MSA) and 73 cadavers without synucleinopathies (Alzheimer disease, progressive supranuclear palsy, corticobasal degeneration, and NNCs). PMCA showed 82% sensitivity (95% CI, 76-88) and 96% specificity (95% CI, 85-100) with autopsy abdominal skin samples from PD cadavers. From posterior cervical and leg skin biopsy tissues from patients with PD and controls without PD, the sensitivity and specificity were 95% (95% CI, 77-100) and 100% (95% CI, 84-100), respectively, for RT-QuIC and 80% (95% CI, 49-96) and 90% (95% CI, 60-100) for PMCA. Conclusions and Relevance This study provides proof-of-concept that skin αSynPseeding activity may serve as a novel biomarker for antemortem diagnoses of PD and other synucleinopathies.

Alteration in cellular prion protein (PrPC) localization on the cell surface through mediation of the glycosylphosphatidylinositol (GPI) anchor has been reported to dramatically affect the formation and infectivity of its pathological isoform (PrPSc). A patient with Gerstmann-Sträussler-Scheinker (GSS) syndrome was previously found to have a nonsense heterozygous PrP-Q227X mutation resulting in an anchorless PrP. However, the allelic origin of this anchorless PrPSc and cellular trafficking of PrPQ227X remain to be determined. Here, we show that PrPSc in the brain of this GSS patient is mainly composed of the mutant but not wild-type PrP (PrPWt), suggesting pathological PrPQ227X is incapable of recruiting PrPWt in vivo. This mutant anchorless protein, however, is able to recruit PrPWt from humanized transgenic mouse brain but not from autopsied human brain homogenates to produce a protease-resistant PrPSc-like form in vitro by protein misfolding cyclic amplification (PMCA). To further investigate the characteristics of this mutation, constructs expressing human PrPQ227X or PrPWt were transfected into neuroblastoma cells (M17). Fractionation of the M17 cells demonstrated that most PrPWt is recovered in the cell lysate fraction, while most of the mutant PrPQ227X is recovered in the medium fraction, consistent with the results obtained by immunofluorescence microscopy. Two-dimensional gel-electrophoresis and Western blotting showed that cellular PrPQ227X spots clustered at molecular weights of 22–25 kDa with an isoelectric point (pI) of 3.5–5.5, whereas protein spots from the medium are at 18–26 kDa with a pI of 7–10. Our findings suggest that the role of GPI anchor in prion propagation between the anchorless mutant PrP and wild-type PrP relies on the cellular distribution of the protein.

BackgroundThe definite diagnosis of human sporadic Creutzfeldt-Jakob disease (sCJD) largely depends on postmortem neuropathology and PrPSc detection in the brain. The development of prion RT-QuIC of cerebrospinal fluid (CSF) samples makes it possible for premortem diagnosis for sCJD. However the diagnostic potential of RT-QuIC of skin specimen for probable sCJD is not well researched. This study is to evaluate the diagnostic potential of RT-QuIC of skin specimen in human prion diseases.MethodsWe collected the paired skin and CSF samples from 29 recruited alive patients referred to Chinese CJD surveillance center, including 12 probable sCJD, 9 non-CJD, 3 genetic prion disease (gPrD) and 5 cases whose diagnoses still pending. The samples were subjected to RT-QuIC assays using recombinant hamster PrP protein rHaPrP90-231 as the substrate.ResultsAll 12 probable sCJD patients, 4 pending, and 1 T188K genetic CJD (gCJD) cases showed positive prion-seeding activity, while all 9 non-CJD patients were negative. CSF RT-QuIC positive seeding activity was only observed in 5 probable sCJD patients.ConclusionsOur preliminary data indicate high sensitivity and specificity of skin RT-QuIC in prion detection for Chinese probable sCJD and highlight that skin prion-seeding activity is a reliable biomarker for premortem diagnosis of human prion disease.

ObjectiveTo determine whether (1) immunofluorescence is a reproducible technique in detecting misfolded α-synuclein in skin nerves and subsequently whether (2) immunofluorescence and real-time quaking-induced conversion (RT-QuIC) (both in skin and CSF) show a comparable in vivo diagnostic accuracy in distinguishing synucleinopathies from non-synucleinopathies in a large cohort of patients.MethodsWe prospectively recruited 90 patients fulfilling clinical and instrumental diagnostic criteria for all synucleinopathies variants and non-synucleinopathies (mainly including Alzheimer disease, tauopathies, and vascular parkinsonism or dementia). Twenty-four patients with mainly peripheral neuropathies were used as controls. Patients underwent skin biopsy for immunofluorescence and RT-QuIC; CSF was examined in patients who underwent lumbar puncture for diagnostic purposes. Immunofluorescence and RT-QuIC analysis were made blinded to the clinical diagnosis.ResultsImmunofluorescence showed reproducible results between 2 pairs of neighboring skin samples. Both immunofluorescence and RT-QuIC showed high sensitivity and specificity in discriminating synucleinopathies from non-synucleinopathies and controls but immunofluorescence presented higher diagnostic accuracy. Immunofluorescence presented a good level of agreement with RT-QuIC in both skin and CSF in synucleinopathies.ConclusionsBoth immunofluorescence and RT-QuIC showed high diagnostic accuracy, although immunofluorescence displayed the better value as well as optimal reproducibility; they presented a good level of agreement in synucleinopathies, supporting the use of less invasive tests such as skin immunofluorescence or RT-QuIC instead of CSF RT-QuIC as a diagnostic tool for synucleinopathies.Classification of EvidenceThis study provides Class III evidence that immunofluorescence or RT-QuIC accurately distinguish synucleinopathies from non-synucleinopathies.

The iterative innovation of processing technology is one of the important tasks in studies on processing of traditional Chinese medicine(TCM). It is also the prerequisite for modern, refined, automatic and intelligent manufacturing of TCM pieces. Microwave processing is a new fire processing technique developed in the recent 30 years, with a unique thermodynamic form, and energy transfer and transformation laws. Moreover, it owns the advantages of a high processing efficiency, good product properties and low production energy consumption, with great application prospects. This paper introduced the study overview of microwave expansion technology in the food industry, reviewed the origin of microwave processing technology of TCM, and expounded the basic concept, principle and main purpose of microwave processing technology used in TCM. Then, the impacts of drug factors and microwave factors on the microwave processing effect were summarized, the industrial equipment that could be used for microwave processing was listed, and the impacts of microwave heating on starch, polysaccharide, protein and other components in Chinese herbal medicines were analyzed. Furthermore, the study advance of microwave processing of 14 herbs was investigated, including Aconiti Lateralis Radix Praeparaia, Galli Gigerii Endothelium Corneum and Asini Corii Colla; and the appearance and components of herbs processed by traditional processing method and microwave processing method were compared, so as to reveal the opportunities and challenges of microwave processing technology in the industrial transformation. We hoped that the systematic study of microwave processing technology could provide new ideas and techniques for the high-quality and high-level development of the TCM pieces industry in the new era, and promote its inheritance, innovation and transformation.

Cerebral organoids (COs) are a self-organizing three-dimensional brain tissue mimicking the human cerebral cortex. COs are a promising new system for modelling pathological features of neurological disorders, including prion diseases. COs expressing normal prion protein (PrPC) are susceptible to prion infection when exposed to the disease isoforms of PrP (PrPD). This causes the COs to develop aspects of prion disease pathology considered hallmarks of disease, including the production of detergent-insoluble, protease-resistant misfolded PrPD species capable of seeding the production of more misfolded species. To determine whether COs can model aspects of familial prion diseases, we produced COs from donor fibroblasts carrying the E200K mutation, the most common cause of human familial prion disease. The mature E200K COs were assessed for the hallmarks of prion disease. We found that up to 12 months post-differentiation, E200K COs harbored no PrPD as confirmed by the absence of detergent-insoluble, protease-resistant, and seeding-active PrP species. Our results suggest that the presence of the E200K mutation within the prion gene is insufficient to cause disease in neuronal tissue. Therefore, other factors, such as further genetic modifiers or aging processes, may influence the onset of misfolding.

// Xiangzhu Xiao 1,* , Pingping Shen 1,2,* , Zerui Wang 1,2,* , Johnny Dang 1 , Alise Adornato 1 , Lewis S. Zou 1 , Zhiqian Dong 1 , Jue Yuan 1 , Jiachun Feng 2 , Li Cui 2 and Wen-Quan Zou 1,2,3 1 Department of Pathology, Case Western Reserve University, Cleveland, OH, USA 2 Institute of Neuroscience Center and Neurology Department, The First Hospital of Jilin University, Changchun, Jilin, China 3 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China * These authors have Contributed equally to this study Correspondence to: Li Cui, email: // Wen-Quan Zou, email: // Keywords : caveolin-1, human brain, prion disease, solubility, aggregation, Gerotarget Received : June 02, 2017 Accepted : July 12, 2017 Published : July 21, 2017 Abstract Caveolin-1 is a major component protein of the caveolae—a type of flask shaped, 50-100 nm, nonclathrin-coated, microdomain present in the plasma membrane of most mammalian cells. Caveolin-1 functions as a scaffolding protein to organize and concentrate signaling molecules within the caveolae, which may be associated with its unique physicochemical properties including oligomerization, acquisition of detergent insolubility, and association with cholesterol. Here we demonstrate that caveolin-1 is detected in all brain areas examined and recovered in both detergent-soluble and -insoluble fractions. Surprisingly, the recovered molecules from the two different fractions share a similar molecular size ranging from 200 to 2,000 kDa, indicated by gel filtration. Furthermore, both soluble and insoluble caveolin-1 molecules generate a proteinase K (PK)-resistant C-terminal core fragment upon the PK-treatment, by removing ~36 amino acids from the N-terminus of the protein. Although it recognizes caveolin-1 from A431 cell lysate, an antibody against the C-terminus of caveolin-1 fails to detect the brain protein by Western blotting, suggesting that the epitope in the brain caveolin-1 is concealed. No significant differences in the physicochemical properties of caveolin-1 between uninfected and prion-infected brains are observed.

Tau aggregates are present in a large number of neurodegenerative diseases known as “tauopathies”, including Alzheimer’s disease (AD). As there are six human tau isoforms in brain tissues and both 3R and 4R isoforms have been observed in the neuronal inclusions, we tested whether tau isoforms behave differently in aggregation. We discovered that all six tau isoforms are capable of forming PHF-tau like filaments and the 3R tau isoforms aggregate significantly faster than their 4R counterparts. We further mapped key segments of tau isoforms that contribute to their aggregation kinetics, where it was determined that microtubule binding domains R2 and R3 were the major contributors to tau aggregation. To evaluate the feasibility of using the six recombinant tau isoforms as substrates to amplify misfolded tau, we demonstrated that full-length human tau isoforms can seed and detect misfolded tau from the post-mortem AD brain tissues with high specificity by an ultrasensitive technology termed real-time quaking-induced conversion (RT-QuIC). Mass spectrometric analysis of PHF-tau samples extracted from AD brains identified peptides corresponding to all major forms of human brain tau isoforms along with a consensus hyperphosphorylated peptide near the C-terminus. Together, our findings not only reveal new aggregation kinetic properties of human tau isoforms, support the development of methods to quantitatively measure misfolded human tau isoforms in AD brains, but also uncover the capability of full-length human tau isoforms as substrates for “prion-like” tau seeding by RT-QuIC assays that may be used for new biomarker development for AD and other tauopathy diagnosis.

Prion or PrPSc is the proteinaceous infectious agent causing prion diseases in various mammalian species. Despite decades of research, the structural basis for PrPSc formation and prion infectivity remains elusive. To understand the role of the hydrophobic region in forming infectious prion at the molecular level, we report X-ray crystal structures of mouse (Mo) prion protein (PrP) (residues 89–230) in complex with a nanobody (Nb484). Using the recombinant prion propagation system, we show that the binding of Nb484 to the hydrophobic region of MoPrP efficiently inhibits the propagation of proteinase K resistant PrPSc and prion infectivity. In addition, when added to cultured mouse brain slices in high concentrations, Nb484 exhibits no neurotoxicity, which is drastically different from other neurotoxic anti-PrP antibodies, suggesting that the Nb484 can be a potential therapeutic agent against prion disease. In summary, our data provides the first structure-function evidence supporting a crucial role of the hydrophobic region of PrP in forming an infectious prion., Author summary Prion disease is caused by the misfolding of normal prion protein (PrPC) to its pathogenic isoform, termed PrPSc. The underlying mechanism for such fatal misfolding is still unknown, which greatly impedes the development of efficacious therapeutic strategies against these currently incurable diseases. Previously, we reported the crystal structure of human PrP in complex with a nanobody (Nb484), which could inhibit mouse prion propagation in a cell culture model. To understand the molecular mechanism for the inhibitory action of Nb484, in this study, firstly we determine the crystal structures of mouse PrP-Nb484 complexes and show that Nb484 binds to and stabilizes the hydrophobic region of PrP. Then in our newly developed recombinant prion propagation system, we show that Nb484 inhibits prion propagation through the competitive inhibition mechanism. We further demonstrate that, contrary to certain neurotoxic anti-PrP antibodies, the inhibitory Nb484 exhibits no neurotoxicity on cultured organotypic brain slices, indicating the great therapeutic potential of Nb484. In summary, our current study provides the first structure-function evidence supporting a critical role of the hydrophobic region in forming the infectious prion and highlights the therapeutic potential of Nb484.

International audience; The original version of this article unfortunately contained a mistake. The email address Dr. Wen-Quan Zou, one of the corresponding authors should be written as wxz6@case.edu instead of wxz@case.edu.

Real-time quaking-induced conversion (RT-QuIC) assay is a newly established PrP

SUMMARY Since the term protein was first coined in 1838 and protein was discovered to be the essential component of fibrin and albumin, all cellular proteins were presumed to play beneficial roles in plants and mammals. However, in 1967, Griffith proposed that proteins could be infectious pathogens and postulated their involvement in scrapie, a universally fatal transmissible spongiform encephalopathy in goats and sheep. Nevertheless, this novel hypothesis had not been evidenced until 1982, when Prusiner and coworkers purified infectious particles from scrapie-infected hamster brains and demonstrated that they consisted of a specific protein that he called a “prion.” Unprecedentedly, the infectious prion pathogen is actually derived from its endogenous cellular form in the central nervous system. Unlike other infectious agents, such as bacteria, viruses, and fungi, prions do not contain genetic materials such as DNA or RNA. The unique traits and genetic information of prions are believed to be encoded within the conformational structure and posttranslational modifications of the proteins. Remarkably, prion-like behavior has been recently observed in other cellular proteins—not only in pathogenic roles but also serving physiological functions. The significance of these fascinating developments in prion biology is far beyond the scope of a single cellular protein and its related disease.

Both sporadic variably protease-sensitive prionopathy (VPSPr) and familial Creutzfeldt-Jakob disease linked to the prion protein (PrP) V180I mutation (fCJDV180I) have been found to share a unique pathological prion protein (PrPSc) that lacks the protease-resistant PrPSc glycosylated at residue 181 because two of four PrP glycoforms are apparently not converted into the PrPSc from their cellular PrP (PrPC). To investigate the seeding activity of these unique PrPSc molecules, we conducted in vitro prion conversion experiments using serial protein misfolding cyclic amplification (sPMCA) and real-time quaking-induced conversion (RT-QuIC) assays with different PrPC substrates. We observed that the seeding of PrPSc from VPSPr or fCJDV180I in the sPMCA reaction containing normal human or humanized transgenic (Tg) mouse brain homogenates generated PrPSc molecules that unexpectedly exhibited a dominant diglycosylated PrP isoform along with PrP monoglycosylated at residue 181. The efficiency of PrPSc amplification was significantly higher in non-CJDMM than in non-CJDVV human brain homogenate, whereas it was higher in normal TgVV than in TgMM mouse brain homogenate. PrPC from the mixture of normal TgMM and Tg mouse brain expressing PrPV180I mutation (Tg180) but not TgV180I alone was converted into PrPSc by seeding with the VPSPr or fCJDV180I. The RT-QuIC seeding activity of PrPSc from VPSPr and fCJDV180I was significantly lower than that of sCJD. Our results suggest that the formation of glycoform-selective prions may be associated with an unidentified factor in the affected brain and the glycoform-deficiency of PrPSc does not affect the glycoforms of in vitro newly amplified PrPSc. Electronic supplementary material The online version of this article (10.1007/s12035-018-1459-0) contains supplementary material, which is available to authorized users.

Sporadic Creutzfeldt-Jakob disease (sCJD), the most common human prion disease, is transmissible through iatrogenic routes due to abundant infectious prions [misfolded forms of the prion protein (PrPSc)] in the central nervous system (CNS). Some epidemiological studies have associated sCJD risk with non-CNS surgeries. We explored the potential prion seeding activity and infectivity of skin from sCJD patients. Autopsy or biopsy skin samples from 38 patients [21 sCJD, 2 variant CJD (vCJD), and 15 non-CJD] were analyzed by Western blotting and real-time quaking-induced conversion (RT-QuIC) for PrPSc. Skin samples from two patients were further examined for prion infectivity by bioassay using two lines of humanized transgenic mice. Western blotting revealed dermal PrPSc in one of five deceased sCJD patients and one of two vCJD patients. However, the more sensitive RT-QuIC assay detected prion seeding activity in skin from all 23 CJD decedents but not in skin from any non-CJD control individuals (with other neurological conditions or other diseases) during blinded testing. Although sCJD patient skin contained ~103- to 105-fold lower prion seeding activity than did sCJD patient brain tissue, all 12 mice from two transgenic mouse lines inoculated with sCJD skin homogenates from two sCJD patients succumbed to prion disease within 564 days after inoculation. Our study demonstrates that the skin of sCJD patients contains both prion seeding activity and infectivity, which raises concerns about the potential for iatrogenic sCJD transmission via skin.

In most human sporadic prion diseases the phenotype is consistently associated with specific pairings of the genotype at codon 129 of the prion protein gene and conformational properties of the scrapie PrP (PrPSc) grossly identified types 1 and 2. This association suggests that the 129 genotype favours the selection of a distinct strain that in turn determines the phenotype. However, this mechanism cannot play a role in the phenotype determination of sporadic fatal insomnia (sFI) and a subtype of sporadic Creutzfeldt-Jakob disease (sCJD) identified as sCJDMM2, which share 129 MM genotype and PrPSc type 2 but are associated with quite distinct phenotypes. Our detailed comparative study of the PrPSc conformers has revealed major differences between the two diseases, which preferentially involve the PrPSc component that is sensitive to digestion with proteases (senPrPSc) and to a lesser extent the resistant component (resPrPSc). We conclude that these variations are consistent with two distinct strains in sFI and sCJDMM2, and that the rarer sFI is the result of a variant strain selection pathway that might be favoured by a different brain site of initial PrPSc formation in the two diseases.

International audience; Prions are infectious proteins that cause a group of fatal transmissible diseases in animals and humans. The scrapie isoform (PrPSc) of the cellular prion protein (PrPC) is the only known component of the prion. Several lines of evidence have suggested that the formation and molecular features of PrPSc are associated with an abnormal unfolding/refolding process. Quiescin-sulfhydryl oxidase (QSOX) plays a role in protein folding by introducing disulfides into unfolded reduced proteins. Here we report that QSOX inhibits human prion propagation in protein misfolding cyclic amplification reactions and murine prion propagation in scrapie-infected neuroblastoma cells. Moreover, QSOX preferentially binds PrPSc from prion-infected human or animal brains, but not PrPC from uninfected brains. Surface plasmon resonance of the recombinant mouse PrP (moPrP) demonstrates that the affinity of QSOX for monomer is significantly lower than that for octamer (312 nM vs 1.7 nM). QSOX exhibits much lower affinity for N-terminally truncated moPrP (PrP89-230) than for the full-length moPrP (PrP23-231) (312 nM vs 2 nM), suggesting that the N-terminal region of PrP is critical for the interaction of PrP with QSOX. Our study indicates that QSOX may play a role in prion formation, which may open new therapeutic avenues for treating prion diseases.

Prions are infectious proteins that cause a group of fatal transmissible diseases in animals and humans. The scrapie isoform (PrPSc) of the cellular prion protein (PrPC) is the only known component of the prion. Several lines of evidence have suggested that the formation and molecular features of PrPSc are associated with an abnormal unfolding/refolding process. Quiescin-sulfhydryl oxidase (QSOX) plays a role in protein folding by introducing disulfides into unfolded reduced proteins. Here we report that QSOX inhibits human prion propagation in protein misfolding cyclic amplification reactions and murine prion propagation in scrapie-infected neuroblastoma cells. Moreover, QSOX preferentially binds PrPSc from prion-infected human or animal brains, but not PrPC from uninfected brains. Surface plasmon resonance of the recombinant mouse PrP (moPrP) demonstrates that the affinity of QSOX for monomer is significantly lower than that for octamer (312 nM vs 1.7 nM). QSOX exhibits much lower affinity for N-terminally truncated moPrP (PrP89-230) than for the full-length moPrP (PrP23-231) (312 nM vs 2 nM), suggesting that the N-terminal region of PrP is critical for the interaction of PrP with QSOX. Our study indicates that QSOX may play a role in prion formation, which may open new therapeutic avenues for treating prion diseases.