Prion protein scrapie and the normal cellular prion protein

Cellular Prion Protein Conformational Shift after Liquid-Liquid Phase Separation Regulated by a Polymeric Antagonist and Mutations

Liquid-liquid phase separation (LLPS) of intrinsically disordered proteins has been associated with neurodegenerative diseases, although direct mechanisms are poorly defined. Here, we report on a maturation process for the cellular prion protein (PrPC) that involves a conformational change after LLPS and is regulated by mutations and poly(4-styrenesulfonic acid-co-maleic acid) (PSCMA), a molecule that has been reported to rescue Alzheimer's disease-related cognitive deficits by antagonizing the interaction between PrPC and amyloid-β oligomers (Aβo). We show that PSCMA can induce reentrant LLPS of PrPC and lower the saturation concentration (Csat) of PrPC by 100-fold. Regardless of the induction method, PrPC molecules subsequently undergo a maturation process to restrict molecular motion in a more solid-like state. The PSCMA-induced LLPS of PrPC stabilizes the intermediate LLPS conformational state detected by NMR, though the final matured β-sheet-rich state of PrPC is indistinguishable between induction conditions. The disease-associated E200 K mutation of PrPC also accelerates maturation. This post-LLPS shift in protein conformation and dynamics is a possible mechanism of LLPS-induced neurodegeneration.

Unfolding Mechanism and Fibril Formation Propensity of Human Prion Protein in the Presence of Molecular Crowding Agents

The pathological process of prion diseases implicates that the normal physiological cellular prion protein (PrPC) converts into misfolded abnormal scrapie prion (PrPSc) through post-translational modifications that increase β-sheet conformation. We recently demonstrated that HuPrP(90-231) thermal unfolding is partially irreversible and characterized by an intermediate state (β-PrPI), which has been revealed to be involved in the initial stages of PrPC fibrillation, with a seeding activity comparable to that of human infectious prions. In this study, we report the thermal unfolding characterization, in cell-mimicking conditions, of the truncated (HuPrP(90-231)) and full-length (HuPrP(23-231)) human prion protein by means of CD and NMR spectroscopy, revealing that HuPrP(90-231) thermal unfolding is characterized by two successive transitions, as in buffer solution. The amyloidogenic propensity of HuPrP(90-231) under crowded conditions has also been investigated. Our findings show that although the prion intermediate, structurally very similar to β-PrPI, forms at a lower temperature compared to when it is dissolved in buffer solution, in cell-mimicking conditions, the formation of prion fibrils requires a longer incubation time, outlining how molecular crowding influences both the equilibrium states of PrP and its kinetic pathways of folding and aggregation.

Prion protein alters viral control and enhances pathology after perinatal cytomegalovirus infection

Cytomegalovirus (CMV) infection poses risks to newborns, necessitating effective therapies. Given that the damage includes both viral infection of brain cells and immune system-related damage, here we investigate the involvement of cellular prion protein (PrP), which plays vital roles in neuroprotection and immune regulation. Using a murine model, we show the role of PrP in tempering neonatal T cell immunity during CMV infection. PrP-null mice exhibit enhanced viral control through elevated virus-specific CD8 T cell responses, leading to reduced viral titers and pathology. We further unravel the molecular mechanisms by showing CMV-induced upregulation followed by release of PrP via the metalloproteinase ADAM10, impairing CD8 T cell response specifically in neonates. Additionally, we confirm PrP downregulation in human CMV (HCMV)-infected fibroblasts, underscoring the broader relevance of our observations beyond the murine model. Furthermore, our study highlights how PrP, under the stress of viral pathogenesis, reveals its impact on neonatal immune modulation.

Oscillations in Neuronal Activity: A Neuron-Centered Spatiotemporal Model of the Unfolded Protein Response in Prion Diseases

Many neurodegenerative diseases (NDs) are characterized by the slow spatial spread of toxic protein species in the brain. The toxic proteins can induce neuronal stress, triggering the Unfolded Protein Response (UPR), which slows or stops protein translation and can indirectly reduce the toxic load. However, the UPR may also trigger processes leading to apoptotic cell death and the UPR is implicated in the progression of several NDs. In this paper, we develop a novel mathematical model to describe the spatiotemporal dynamics of the UPR mechanism for prion diseases. Our model is centered around a single neuron, with representative proteins P (healthy) and S (toxic) interacting with heterodimer dynamics (S interacts with P to form two S's). The model takes the form of a coupled system of nonlinear reaction-diffusion equations with a delayed, nonlinear flux for P (delay from the UPR). Through the delay, we find parameter regimes that exhibit oscillations in the P- and S-protein levels. We find that oscillations are more pronounced when the S-clearance rate and S-diffusivity are small in comparison to the P-clearance rate and P-diffusivity, respectively. The oscillations become more pronounced as delays in initiating the UPR increase. We also consider quasi-realistic clinical parameters to understand how possible drug therapies can alter the course of a prion disease. We find that decreasing the production of P, decreasing the recruitment rate, increasing the diffusivity of S, increasing the UPR S-threshold, and increasing the S clearance rate appear to be the most powerful modifications to reduce the mean UPR intensity and potentially moderate the disease progression.

First report of a novel 108 bp deletion and five novel SNPs in PRNP gene of stray cats and in silico analysis of their possible relation with feline spongiform encephalopathy

Prion diseases are fatal neurodegenerative diseases affecting humans and animals. A relationship between variations in the prion gene of some species and susceptibility to prion diseases has been detected. However, variations in the prion protein of cats that have close contact with humans and their effect on prion protein are not well-known. Therefore, this study aimed to investigate the variations of prion protein-encoding gene (PRNP gene) in stray cats and to evaluate variants detected in terms of genetic factors associated with susceptibility or resistance to feline spongiform encephalopathy using bioinformatics tools. For this, cat DNA samples were amplified by a PCR targeting PRNP gene and then sequenced to reveal the variations. Finally, the effects of variants on prion protein were predicted by bioinformatics tools. According to the obtained results, a novel 108 bp deletion and nine SNPs were detected. Among SNPs, five (c314A>G, c.454T>A, c.579G>C, c.642G>C and c.672G>C) were detected for the first time in this study. Bioinformatics findings showed that c.579G>C (Q193H), c.454T>A (Y152N) and c.457G>A (E153K) variants have deleterious effects on prion protein and c.579G>C (Q193H) has high amyloid propensities. This study demonstrates prion protein variants of stray cats and their deleterious effects on prion protein for the first time.

Exosomes: Membrane-associated proteins, challenges and perspectives

Membrane proteins determine the precise function of each membrane and, therefore, the function of each cell type. These proteins essential roles in cell physiology, participating in the maintenance of the cell metabolism, its homeostasis or promoting proper cell growth. Membrane proteins, as has long been described, are located both in the plasma membrane and in complex subcellular structures. However, they can also be released into the extracellular environment associated with extracellular vesicles (EVs). To date, most of the research have been focused on understanding the role of exosomal RNA in several processes. Recently, there has been increasing interest in studying the function of exosome membrane proteins for exosome-based therapy, but not much research has been done yet on the function of exosome membrane proteins. One of the major limitations of studying exosome membrane proteins and their application to translational research of exosome-based therapeutics is the low yield of exosome isolation. Here, we have introduced a new perspective on exosome membrane protein research by reviewing studies showing the important role of exosome membrane proteins in exosome-based therapies. Furthermore, we have proposed a new strategy to boost the yield of exosome isolation: hybridization of liposomes with exosome-derived membrane. Liposomes have already been reported to affect the cell excitation to increase exosome production in tumor cells. Therefore, increasing cellular uptake of these liposomes would enhance exosome release by increasing cellular excitation. This new perspective could be a breakthrough in exosome-based therapeutic research.

Dysbiosis of the gut microbiota and its effect on α-synuclein and prion protein misfolding: consequences for neurodegeneration

Abnormal behavior of α-synuclein and prion proteins is the hallmark of Parkinson's disease (PD) and prion illnesses, respectively, being complex neurological disorders. A primary cause of protein aggregation, brain injury, and cognitive loss in prion illnesses is the misfolding of normal cellular prion proteins (PrPC) into an infectious form (PrPSc). Aggregation of α-synuclein causes disruptions in cellular processes in Parkinson's disease (PD), leading to loss of dopamine-producing neurons and motor symptoms. Alteration in the composition or activity of gut microbes may weaken the intestinal barrier and make it possible for prions to go from the gut to the brain. The gut-brain axis is linked to neuroinflammation; the metabolites produced by the gut microbiota affect the aggregation of α-synuclein, regulate inflammation and immunological responses, and may influence the course of the disease and neurotoxicity of proteins, even if their primary targets are distinct proteins. This thorough analysis explores the complex interactions that exist between the gut microbiota and neurodegenerative illnesses, particularly Parkinson's disease (PD) and prion disorders. The involvement of the gut microbiota, a complex collection of bacteria, archaea, fungi, viruses etc., in various neurological illnesses is becoming increasingly recognized. The gut microbiome influences neuroinflammation, neurotransmitter synthesis, mitochondrial function, and intestinal barrier integrity through the gut-brain axis, which contributes to the development and progression of disease. The review delves into the molecular mechanisms that underlie these relationships, emphasizing the effects of microbial metabolites such as bacterial lipopolysaccharides (LPS), and short-chain fatty acids (SCFAs) in regulating brain functioning. Additionally, it looks at how environmental influences and dietary decisions affect the gut microbiome and whether they could be risk factors for neurodegenerative illnesses. This study concludes by highlighting the critical role that the gut microbiota plays in the development of Parkinson's disease (PD) and prion disease. It also provides a promising direction for future research and possible treatment approaches. People afflicted by these difficult ailments may find hope in new preventive and therapeutic approaches if the role of the gut microbiota in these diseases is better understood.

Prospective 25-year surveillance of prion diseases in France, 1992 to 2016: a slow waning of epidemics and an increase in observed sporadic forms

BackgroundPrion diseases are rare, fatal disorders that have repeatedly raised public health concerns since the early 1990s. An active prion disease surveillance network providing national level data was implemented in France in 1992.AimWe aimed to describe the epidemiology of sporadic, genetic and infectious forms of prion diseases in France since surveillance implementation.MethodsWe included all suspected cases notified from January 1992 to December 2016, and cases who died during the period with a definite or probable prion disease diagnosis according to EuroCJD criteria. Demographic, clinical, genetic, neuropathological and biochemical data were collected.ResultsIn total, 25,676 suspected cases were notified and 2,907 were diagnosed as prion diseases, including 2,510 (86%) with sporadic Creutzfeldt-Jakob disease (sCJD), 240 (8%) genetic and 157 (6%) with infectious prion disease. Suspected cases and sCJD cases increased over time. Younger sCJD patients (≤ 50 years) showed phenotypes related to a distinct molecular subtype distribution vs those above 50 years. Compared to other European countries, France has had a higher number of cases with iatrogenic CJD after growth hormone treatment and variant CJD (vCJD) linked to bovine spongiform encephalopathy (second after the United Kingdom), but numbers slowly decreased over time.ConclusionWe observed a decrease of CJD infectious forms, demonstrating the effectiveness of measures to limit human exposure to exogenous prions. However, active surveillance is needed regarding uncertainties about future occurrences of vCJD, possible zoonotic potential of chronic wasting diseases in cervids and increasing trends of sCJD observed in France and other countries.

Realization of Amyloid-like Aggregation as a Common Cause for Pathogenesis in Diseases

Amyloids were conventionally referred to as extracellular and intracellular accumulation of Aβ42 peptide, which causes the formation of plaques and neurofibrillary tangles inside the brain leading to the pathogenesis in Alzheimer's disease. Subsequently, amyloid-like deposition was found in the etiology of prion diseases, Parkinson's disease, type II diabetes, and cancer, which was attributed to the aggregation of prion protein, α-Synuclein, islet amyloid polypeptide protein, and p53 protein, respectively. Hence, traditionally amyloids were considered aggregates formed exclusively by proteins or peptides. However, since the last decade, it has been discovered that other metabolites, like single amino acids, nucleobases, lipids, glucose derivatives, etc., have a propensity to form amyloid-like toxic assemblies. Several studies suggest direct implications of these metabolite assemblies in the patho-physiology of various inborn errors of metabolisms like phenylketonuria, tyrosinemia, cystinuria, and Gaucher's disease, to name a few. In this review, we present a comprehensive literature overview that suggests amyloid-like structure formation as a common phenomenon for disease progression and pathogenesis in multiple syndromes. The review is devoted to providing readers with a broad knowledge of the structure, mode of formation, propagation, and transmission of different extracellular amyloids and their implications in the pathogenesis of diseases. We strongly believe a review on this topic is urgently required to create awareness about the understanding of the fundamental molecular mechanism behind the origin of diseases from an amyloid perspective and possibly look for a common therapeutic strategy for the treatment of these maladies by designing generic amyloid inhibitors.

Amyloid precursor protein (APP) and amyloid β (Aβ) interact with cell adhesion molecules: Implications in Alzheimer’s disease and normal physiology

Alzheimer’s disease (AD) is an incurable neurodegenerative disorder in which dysfunction and loss of synapses and neurons lead to cognitive impairment and death. Accumulation and aggregation of neurotoxic amyloid-β (Aβ) peptides generated via amyloidogenic processing of amyloid precursor protein (APP) is considered to play a central role in the disease etiology. APP interacts with cell adhesion molecules, which influence the normal physiological functions of APP, its amyloidogenic and non-amyloidogenic processing, and formation of Aβ aggregates. These cell surface glycoproteins also mediate attachment of Aβ to the neuronal cell surface and induce intracellular signaling contributing to Aβ toxicity. In this review, we discuss the current knowledge surrounding the interactions of cell adhesion molecules with APP and Aβ and analyze the evidence of the critical role these proteins play in regulating the processing and physiological function of APP as well as Aβ toxicity. This is a necessary piece of the complex AD puzzle, which we should understand in order to develop safe and effective therapeutic interventions for AD.

Role of Biomarkers for the Diagnosis of Prion Diseases: A Narrative Review

Prion diseases are progressive and irreversible neurodegenerative disorders with a low incidence (1.5–2 cases per million per year). Genetic (10–15%), acquired (anecdotal) and sporadic (85%) forms of the disease have been described. The clinical spectrum of prion diseases is very varied, although the most common symptoms are rapidly progressive dementia, cerebellar ataxia and myoclonus. Mean life expectancy from the onset of symptoms is 6 months. There are currently diagnostic criteria based on clinical phenotype, as well as neuroimaging biomarkers (magnetic resonance imaging), neurophysiological tests (electroencephalogram and polysomnogram), and cerebrospinal fluid biomarkers (14-3-3 protein and real-time quaking-induced conversion (RT-QuIC)). The sensitivity and specificity of some of these tests (electroencephalogram and 14-3-3 protein) is under debate and the applicability of other tests, such as RT-QuIC, is not universal. However, the usefulness of these biomarkers beyond the most frequent prion disease, sporadic Creutzfeldt–Jakob disease, remains unclear. Therefore, research is being carried out on new, more efficient cerebrospinal fluid biomarkers (total tau, ratio total tau/phosphorylated tau and neurofilament light chain) and potential blood biomarkers (neurofilament light chain, among others) to try to universalize access to early diagnosis in the case of prion diseases.

Genome-Wide Methylation Profiling in the Thalamus of Scrapie Sheep

Scrapie is a neurodegenerative disorder belonging to the group of transmissible spongiform encephalopathy (TSE). Scrapie occurs in sheep and goats, which are considered good natural animal models of these TSE. Changes in DNA methylation occur in the central nervous system (CNS) of patients suffering from prion-like neurodegenerative diseases, such as Alzheimer's disease. Nevertheless, potential DNA methylation alterations have not yet been investigated in the CNS of any prion disease model or naturally infected cases, neither in humans nor in animals. Genome-wide DNA methylation patterns were studied in the thalamus obtained from sheep naturally infected with scrapie at a clinical stage (n = 4) and from controls (n = 4) by performing a whole-genome bisulfite sequencing (WGBS) analysis. Ewes carried the scrapie-susceptible ARQ/ARQ PRNP genotype and were sacrificed at a similar age (4–6 years). Although the average genomic methylation levels were similar between the control and the scrapie animals, we identified 8,907 significant differentially methylated regions (DMRs) and 39 promoters (DMPs). Gene Ontology analysis revealed that hypomethylated DMRs were enriched in genes involved in transmembrane transport and cell adhesion, whereas hypermethylated DMRs were related to intracellular signal transduction genes. Moreover, genes highly expressed in specific types of CNS cells and those previously described to be differentially expressed in scrapie brains contained DMRs. Finally, a quantitative PCR (qPCR) validation indicated differences in the expression of five genes (PCDH19, SNCG, WDR45B, PEX1, and CABIN1) that matched the methylation changes observed in the genomic study. Altogether, these results suggest a potential regulatory role of DNA methylation in prion neuropathology.

Patent highlights August-September 2021

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Prions and Neurodegenerative Diseases: A Focus on Alzheimer's Disease

Specific protein misfolding and aggregation are mechanisms underlying various neurodegenerative diseases such as prion disease and Alzheimer's disease (AD). The misfolded proteins are involved in prions, amyloid-β (Aβ), tau, and α-synuclein disorders; they share common structural, biological, and biochemical characteristics, as well as similar mechanisms of aggregation and self-propagation. Pathological features of AD include the appearance of plaques consisting of deposition of protein Aβ and neurofibrillary tangles formed by the hyperphosphorylated tau protein. Although it is not clear how protein aggregation leads to AD, we are learning that the cellular prion protein (PrPC) plays an important role in the pathogenesis of AD. Herein, we first examined the pathogenesis of prion and AD with a focus on the contribution of PrPC to the development of AD. We analyzed the mechanisms that lead to the formation of a high affinity bond between Aβ oligomers (AβOs) and PrPC. Also, we studied the role of PrPC as an AβO receptor that initiates an AβO-induced signal cascade involving mGluR5, Fyn, Pyk2, and eEF2K linking Aβ and tau pathologies, resulting in the death of neurons in the central nervous system. Finally, we have described how the PrPC-AβOs interaction can be used as a new potential therapeutic target for the treatment of PrPC-dependent AD.

The role of membranes in function and dysfunction of intrinsically disordered amyloidogenic proteins

Membrane-protein interactions play a major role in human physiology as well as in diseases pathology. Interaction of a protein with the membrane was previously thought to be dependent on well-defined three-dimensional structure of the protein. In recent decades, however, it has become evident that a large fraction of the proteome, particularly in eukaryotes, stays disordered in solution and these proteins are termed as intrinsically disordered proteins (IDPs). Also, a vast majority of human proteomes have been reported to contain substantially long disordered regions, called intrinsically disordered regions (IDRs), in addition to the structurally ordered regions. IDPs exist in an ensemble of conformations and the conformational flexibility enables IDPs to achieve functional diversity. IDPs (and IDRs) are found to be important players in cell signaling, where biological membranes act as anchors for signaling cascades. Therefore, IDPs modulate the membrane architectures, at the same time membrane composition also affects the binding of IDPs. Because of intrinsic disorders, misfolding of IDPs often leads to formation of oligomers, protofibrils and mature fibrils through progressive self-association. Accumulation of amyloid-like aggregates of some of the IDPs is a known causative agent for numerous diseases. In this chapter we highlight recent advances in understanding membrane interactions of some of the intrinsically disordered proteins involved in the pathogenesis of human diseases.

The Role of Ruthenium Compounds in Neurological Diseases: A Minireview

Ruthenium (Ru) compounds, nitric oxide donors in biological systems, have emerged as a promising therapeutical alternative to conventional drugs in anticancer chemotherapy and as a potential neuroprotective agent, with less cytotoxic effects. This minireview summarizes promising studies with ruthenium complexes and their roles in cancer, neuroinflammation, neurovascular, and neurodegenerative diseases. The up-to-date evidence supports that ruthenium-based compounds have beneficial effects against gliomas, and other types of brain cancers, reduce motor symptoms in models of cerebral ischemia-reperfusion, and may act in the control of nociceptive and inflammatory events, such as seen in early Alzheimer's disease. More studies are needed to fill many current knowledge gaps about the intricate and complex ruthenium biological effects and therapeutic-related mechanisms, stimulating further research. Significance Statement In our minireview, we summarize interesting studies addressing the role of ruthenium compounds on neurological illnesses, focusing on brain cancer, neurovascular and neurodegenerative diseases. No such review is available in the literature.

The Role of Cellular Prion Protein in Cancer Biology: A Potential Therapeutic Target

Prion protein has two isoforms including cellular prion protein (PrP^C) and scrapie prion protein (PrP^Sc). PrP^Sc is the pathological aggregated form of prion protein and it plays an important role in neurodegenerative diseases. PrP^C is a glycosylphosphatidylinositol (GPI)-anchored protein that can attach to a membrane. Its expression begins at embryogenesis and reaches the highest level in adulthood. PrP^C is expressed in the neurons of the nervous system as well as other peripheral organs. Studies in recent years have disclosed the involvement of PrP^C in various aspects of cancer biology. In this review, we provide an overview of the current understanding of the roles of PrP^C in proliferation, cell survival, invasion/metastasis, and stem cells of cancer cells, as well as its role as a potential therapeutic target.

Altered cellular localisation and expression, together with unconventional protein trafficking, of prion protein, PrPC, in type 1 diabetes

AIMS/HYPOTHESIS

Normal cellular prion protein (PrP^C) is a conserved mammalian glycoprotein found on the outer plasma membrane leaflet through a glycophosphatidylinositol anchor. Although PrP^C is expressed by a wide range of tissues throughout the body, the complete repertoire of its functions has not been fully determined. The misfolded pathogenic isoform PrP^Sc (the scrapie form of PrP) is a causative agent of neurodegenerative prion diseases. The aim of this study is to evaluate PrP^C localisation, expression and trafficking in pancreases from organ donors with and without type 1 diabetes and to infer PrP^C function through studies on interacting protein partners.

METHODS

In order to evaluate localisation and trafficking of PrP^C in the human pancreas, 12 non-diabetic, 12 type 1 diabetic and 12 autoantibody-positive organ donor tissue samples were analysed using immunofluorescence analysis. Furthermore, total RNA was isolated from 29 non-diabetic, 29 type 1 diabetic and 24 autoantibody-positive donors to estimate PrP^C expression in the human pancreas. Additionally, we performed PrP^C-specific immunoblot analysis on total pancreatic protein from non-diabetic and type 1 diabetic organ donors to test whether changes in PrP^C mRNA levels leads to a concomitant increase in PrP^C protein levels in human pancreases.

RESULTS

In non-diabetic and type 1 diabetic pancreases (the latter displaying both insulin-positive [INS(+)] and -negative [INS(-)] islets), we found PrP^C in islets co-registering with beta cells in all INS(+) islets and, strikingly, unexpected activation of PrP^C in alpha cells within diabetic INS(-) islets. We found PrP^C localised to the plasma membrane and endoplasmic reticulum (ER) but not the Golgi, defining two cellular pools and an unconventional protein trafficking mechanism bypassing the Golgi. We demonstrate PrP^C co-registration with established protein partners, neural cell adhesion molecule 1 (NCAM1) and stress-inducible phosphoprotein 1 (STI1; encoded by STIP1) on the plasma membrane and ER, respectively, linking PrP^C function with cyto-protection, signalling, differentiation and morphogenesis. We demonstrate that both PRNP (encoding PrP^C) and STIP1 gene expression are dramatically altered in type 1 diabetic and autoantibody-positive pancreases.

CONCLUSIONS/INTERPRETATION

As the first study to address PrP^C expression in non-diabetic and type 1 diabetic human pancreas, we provide new insights for PrP^C in the pathogenesis of type 1 diabetes. We evaluated the cell-type specific expression of PrP^C in the human pancreas and discovered possible connections with potential interacting proteins that we speculate might address mechanisms relevant to the role of PrP^C in the human pancreas.

The Role of Vitamins in Neurodegenerative Disease: An Update

Acquiring the recommended daily allowance of vitamins is crucial for maintaining homeostatic balance in humans and other animals. A deficiency in or dysregulation of vitamins adversely affects the neuronal metabolism, which may lead to neurodegenerative diseases. In this article, we discuss how novel vitamin-based approaches aid in attenuating abnormal neuronal functioning in neurodegeneration-based brain diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and Prion disease. Vitamins show their therapeutic activity in Parkinson's disease by antioxidative and anti-inflammatory activity. In addition, different water- and lipid-soluble vitamins have also prevented amyloid beta and tau pathology. On the other hand, some results also show no correlation between vitamin action and the prevention of neurodegenerative diseases. Some vitamins also exhibit toxic activity too. This review discusses both the beneficial and null effects of vitamin supplementation for neurological disorders. The detailed mechanism of action of both water- and lipid-soluble vitamins is addressed in the manuscript. Hormesis is also an essential factor that is very helpful to determine the effective dose of vitamins. PubMed, Google Scholar, Web of Science, and Scopus were employed to conduct the literature search of original articles, review articles, and meta-analyses.

Tackling prion diseases: a review of the patent landscape

Introduction: Prion diseases are a class of rare and fatal neurodegenerative diseases for which no cure is currently available. They are characterized by conformational conversion of cellular prion protein (PrP^C) into the disease-associated 'scrapie' isoform (PrP^Sc). Under an etiological point of view, prion diseases can be divided into acquired, genetic, and idiopathic form, the latter of which are the most frequent.Areas covered: Therapeutic approaches targeting prion diseases are based on the use of chemical and nature-based compounds, targeting either PrP^C or PrP^Sc or other putative player in pathogenic mechanism. Other proposed anti-prion treatments include passive and active immunization strategies, peptides, aptamers, and PrP^C-directed RNA interference techniques. The treatment efficacy has been mainly assessed in cell lines or animal models of the disease testing their ability to reduce prion accumulation.Expert opinion: The assessed strategies focussing on the identification of an efficient anti-prion therapy faced various issues, which go from permeation of the blood brain barrier to immunological tolerance of the host. Indeed, the use of combinatory approaches, which could boost a synergistic anti-prion effect and lower the potential side effects of single treatments and may represent an extreme powerful and feasible way to tackle prion disease.

Development and Clinical Applications of Antisense Oligonucleotide Gapmers

DNA-like molecules called antisense oligonucleotides have opened new treatment possibilities for genetic diseases by offering a method of regulating gene expression. Antisense oligonucleotides are often used to suppress the expression of mutated genes which may interfere with essential downstream pathways. Since antisense oligonucleotides have been introduced for clinical use, different chemistries have been developed to further improve efficacy, potency, and safety. One such chemistry is a chimeric structure of a central block of deoxyribonucleotides flanked by sequences of modified nucleotides. Referred to as a gapmer, this chemistry produced promising results in the treatment of genetic diseases. Mipomersen and inotersen are examples of recent FDA-approved antisense oligonucleotide gapmers used for the treatment of familial hypercholesterolemia and hereditary transthyretin amyloidosis, respectively. In addition, volanesorsen was conditionally approved in the EU for the treatment of adult patients with familial chylomicronemia syndrome (FCS) in 2019. Many others are being tested in clinical trials or under preclinical development. This chapter will cover the development of mipomersen and inotersen in clinical trials, along with advancement in gapmer treatments for cancer, triglyceride-elevating genetic diseases, Huntington's disease, myotonic dystrophy, and prion diseases.

Unravelling neurological disorders through metallomics-based approaches

Understanding the biological process involving metals and biomolecules in the brain is essential for establishing the origin of neurological disorders, such as neurodegenerative and psychiatric diseases. From this perspective, this critical review presents recent advances in this topic, showing possible mechanisms involving the disruption of metal homeostasis and the pathogenesis of neurological disorders. We also discuss the main challenges observed in metallomics studies associated with neurological disorders, including those related to sample preparation and analyte quantification.

Cellular Prion Protein (PrPc): Putative Interacting Partners and Consequences of the Interaction

Cellular prion protein (PrPc) is a small glycosylphosphatidylinositol (GPI) anchored protein most abundantly found in the outer leaflet of the plasma membrane (PM) in the central nervous system (CNS). PrPc misfolding causes neurodegenerative prion diseases in the CNS. PrPc interacts with a wide range of protein partners because of the intrinsically disordered nature of the protein’s N-terminus. Numerous studies have attempted to decipher the physiological role of the prion protein by searching for proteins which interact with PrPc. Biochemical characteristics and biological functions both appear to be affected by interacting protein partners. The key challenge in identifying a potential interacting partner is to demonstrate that binding to a specific ligand is necessary for cellular physiological function or malfunction. In this review, we have summarized the intracellular and extracellular interacting partners of PrPc and potential consequences of their binding. We also briefly describe prion disease-related mutations at the end of this review.

Prion Protein in Stem Cells: A Lipid Raft Component Involved in the Cellular Differentiation Process

The prion protein (PrP) is an enigmatic molecule with a pleiotropic effect on different cell types; it is localized stably in lipid raft microdomains and it is able to recruit downstream signal transduction pathways by its interaction with various biochemical partners. Since its discovery, this lipid raft component has been involved in several functions, although most of the publications focused on the pathological role of the protein. Recent studies report a key role of cellular prion protein (PrP^C) in physiological processes, including cellular differentiation. Indeed, the PrP^C, whose expression is modulated according to the cell differentiation degree, appears to be part of the multimolecular signaling pathways of the neuronal differentiation process. In this review, we aim to summarize the main findings that report the link between PrP^C and stem cells.

Expression and functions of cellular prion proteins in immunocytes

Prion diseases are fatal neurodegenerative processes caused by the accumulation of the pathological prion protein, PrP^Sc . While pathological lesions are limited to the central nervous system (CNS), disease-specific proteins accumulate and replicate in secondary lymphoid organs prior to neuroinvasion, and their replication there depends on the abundance of cellular prion protein (PrP^C ). PrP^C is expressed in both central and peripheral lymphoid tissues, and up- or downregulates innate and adaptive immune responses. In addition to prion diseases, PrP^C is also immunologically involved in other neurological disorders and infectious diseases, including Alzheimer's disease and human immunodeficiency virus infection. Herein, we summarize the expression and functions of PrP^C in various immunocytes, as well as its immunological and pathological roles in neurodegeneration and infection.

Mutations in Prion Protein Gene: Pathogenic Mechanisms in C-Terminal vs. N-Terminal Domain, a Review

Inherited mutations in the Prion protein (PrP), encoded by the PRNP gene, have been associated with autosomal dominant neurodegenerative disorders, such as Creutzfeldt-Jacob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), and Fatal Familial Insomnia (FFI). Notably, PRNP mutations have also been described in clinical pictures resembling other neurodegenerative diseases, such as frontotemporal dementia. Regarding the pathogenesis, it has been observed that these point mutations are located in the C-terminal region of the PRNP gene and, currently, the potential significance of the N-terminal domain has largely been underestimated. The purpose of this report is to review and provide current insights into the pathogenic mechanisms of PRNP mutations, emphasizing the differences between the C- and N-terminal regions and focusing, in particular, on the lesser-known flexible N-terminal, for which recent biophysical evidence has revealed a physical interaction with the globular C-terminal domain of the cellular prion protein (PrPC).

Secreted cellular prion protein binds doxorubicin and correlates with anthracycline resistance in breast cancer

Anthracyclines are amongst the most effective chemotherapeutics ever developed, but they produce grueling side-effects, serious adverse events and resistance often develops over time. We found that these compounds can be sequestered by secreted cellular Prion protein (PrPC), blocking their cytotoxic activity. This effect was dose-dependent using either cell line-conditioned medium or human serum as a source of PrPC. Genetic depletion of PrPC or inhibition of binding via chelation of ionic copper prevented the interaction and restored cytotoxic activity. This was more pronounced for doxorubicin than its epimer, epirubicin. Investigating the relevance to breast cancer management, we found that the levels of PRNP transcript in pre-treatment tumor biopsies stratified relapse-free survival after neoadjuvant treatment with anthracyclines, particularly amongst doxorubicin-treated patients with residual disease at surgery (p=2.8E-08). These data suggest that local sequestration could mediate treatment resistance. Consistent with this, tumor cell expression of PrPC protein correlated with poorer response to doxorubicin but not epirubicin in an independent cohort analyzed by immunohistochemistry, particularly soluble isoforms released into the extracellular environment by shedding (p=0.015). These findings have important potential clinical implications for frontline regimen decision-making. We suggest there is warranted utility for prognostic PrPC/PRNP assays to guide chemo-sensitization strategies that exploit an understanding of PrPC-anthracycline-copper ion complexes.

Organization of GPI-anchored proteins at the cell surface and its physiopathological relevance

Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are a class of proteins attached to the extracellular leaflet of the plasma membrane via a post-translational modification, the glycolipid anchor. The presence of both glycolipid anchor and protein portion confers them unique features. GPI-APs are expressed in all eukaryotes, from fungi to plants and animals. They display very diverse functions ranging from enzymatic activity, signaling, cell adhesion, cell wall metabolism, neuritogenesis, and immune response. Likewise other plasma membrane proteins, the spatio-temporal organization of GPI-APs is critical for their biological activities in physiological conditions. In this review, we will summarize the latest findings on plasma membrane organization of GPI-APs and the mechanism of its regulation in different cell types. We will also examine the involvement of specific GPI-APs namely the prion protein PrP^C, the Folate Receptor alpha and the urokinase plasminogen activator receptor in human diseases focusing on neurodegenerative diseases and cancer.

Proteomic and Phosphoproteomic Changes Induced by Prolonged Activation of Human Eosinophils with IL-3

Purified human eosinophils treated for 18-24 h with IL-3 adopt a unique activated phenotype marked by increased reactivity to aggregated immunoglobulin-G (IgG). To characterize this phenotype, we quantified protein abundance and phosphorylation by multiplexed isobaric labeling combined with high-resolution mass spectrometry. Purified blood eosinophils of five individuals were treated with IL-3 or no cytokine for 20 h, and comparative data were obtained on abundance of 5385 proteins and phosphorylation at 7330 sites. The 1150 proteins that were significantly up-regulated ( q < 0.05, pairwise t test with Benjamini-Hochberg correction) by IL-3 included the IL3RA and CSF2RB subunits of the IL-3 receptor, the low-affinity receptor for IgG (FCGR2B), 96 proteins involved in protein translation, and 55 proteins involved in cytoskeleton organization. Among the 703 proteins that decreased were 78 mitochondrial proteins. Dynamic regulation of protein phosphorylation was detected at 4218 sites. These included multiple serines in CSF2RB; Y694 of STAT5, a key site of activating phosphorylation downstream of IL3RA/CSF2RB; and multiple sites in RPS6KA1, RPS6, and EIF4B, which are responsible for translational initiation. We conclude that IL-3 up-regulates overall protein synthesis and targets specific proteins for up-regulation, including its own receptor.

Identification of the internal ribosome entry sites (IRES) of prion protein gene

Many studies demonstrated that there are several type bands of prion protein in cells. However, the formation of different prion protein bands is elusive. After several low molecular weight bands of prion protein appeared in SMB-S15 cells infected with scrapie agent Chandler, we think that IRES-dependent translation mechanism induced by prion is involved in the formation of prion protein bands. Then we designed a series of pPrP-GFP fusing plasmids and bicistronic plasmids to identify the IRES sites of prion protein gene and found 3 IRES sites inside of PrP mRNA. We also demonstrated that cap-independent translation of PrP was associated with the ER stress through Tunicamycin treatment. We still found that only IRE1 and PERK pathway regulated the IRES-dependent translation of PrP in this study. Our results indicated, we found that PrP gene had an IRES-dependent translation initiation mechanism and we successfully identified the IRESs inside of the prion protein gene.