Search Results (147)

Prion diseases such as chronic wasting disease involve the conformational conversion of the cellular prion protein (PrP^C) into its misfolded, β-rich isoform (PrP^Sc). While chemical denaturants such as guanidine hydrochloride (GdnHCl) and urea are commonly used to study this process in vitro, their distinct molecular effects on native and misfolded PrP conformers remain incompletely understood. In this study, we employed 500 ns all-atom molecular dynamics simulations and essential collective dynamics analysis to investigate the differential effects of GdnHCl and urea on a composite PrP^C/PrP^Sc system, where white-tailed deer PrP^C interfaces with a corresponding PrP^Sc conformer. GdnHCl was found to preserve interfacial alignment and enhance β-sheet retention in PrP^Sc, while urea promoted partial β-strand dissolution and interfacial destabilization. Both denaturants formed transient contacts with PrP, but urea displaced water hydrogen bonds more extensively. Remarkably, we also observed long-range dynamical coupling across the PrP^C/PrP^Sc interface and between transiently bound solutes and distal protein regions. These findings highlight distinct, denaturant-specific mechanisms of protein destabilization and suggest that localized interactions may propagate non-locally via mechanical or steric pathways. Our results provide molecular-scale insights relevant to prion conversion mechanisms and inform experimental strategies using GdnHCl and urea to modulate misfolding processes in vitro. Full article

The cellular prion protein (PrP^C) is studied in prion diseases, where its misfolded isoform (PrP^Sc) leads to neurodegeneration. PrP^C has also been implicated in several physiological functions. The protein is abundant in the nervous system, and it is critical for cell signaling in cellular communication, where it acts as a scaffold for various signaling molecules. The Reelin signaling pathway, implicated both in Alzheimer’s and prion diseases, engages Dab1, an adaptor protein influencing APP processing and amyloid beta deposition. Here, we show, using Prnp knockout models (Prnp^0/0), that PrP^C modulates Reelin signaling, affecting Dab1 activation and downstream phosphorylation in both neuronal cultures and mouse brains. Notably, Prnp^0/0 mice showed reduced responsiveness to Reelin, associated with altered Dab1 phosphorylation and Fyn kinase activity. Even though no direct interaction between PrP^C and Reelin/ApoER2 was found, Prnp^0/0 neurons showed lower NCAM levels, a well-established PrP^C interactor. Prion infection further disrupted the Reelin signaling pathway, thus downregulating Dab1 and Reelin receptors and altering Reelin processing, like Alzheimer’s disease pathology. These findings emphasize PrP^C indirect role in Dab1 signaling via the NCAM and Fyn pathways, which influence synaptic function and neurodegeneration in prion diseases. Full article

Prion diseases are classically attributed to the accumulation of protease-resistant prion protein (PrP^Sc); however, recent evidence suggests that alternative misfolded prion conformers and systemic inflammatory factors may also contribute to neurodegeneration. This study investigated whether recombinant moPrP^Res, generated by incubating wild-type mouse PrP^C with bacterial lipopolysaccharide (LPS), can induce prion-like disease in FVB/N female mice, whether LPS alone causes neurodegeneration, and how LPS modulates disease progression in mice inoculated with the Rocky Mountain Laboratory (RML) strain of prions. Wild-type female FVB/N mice were randomized into six subcutaneous treatment groups: saline, LPS, moPrP^Res, moPrP^Res + LPS, RML, and RML + LPS. Animals were monitored longitudinally for survival, body weight, and clinical signs. Brain tissues were analyzed histologically and immunohistochemically for vacuolar degeneration, PrP^Sc accumulation, reactive astrogliosis, and amyloid-β plaque deposition. Recombinant moPrP^Res induced a progressive spongiform encephalopathy characterized by widespread vacuolation and astrogliosis, yet with no detectable PrP^Sc by Western blot or immunohistochemistry. LPS alone triggered a distinct neurodegenerative phenotype, including cerebellar amyloid-β plaque accumulation and terminal-stage spongiosis, with approximately 40% mortality by the end of the study. Co-administration of moPrP^Res and LPS resulted in variable regional pathology and intermediate survival (50% at 750 days post-inoculation). Interestingly, RML + LPS co-treatment led to earlier clinical onset and mortality compared to RML alone; however, vacuolation levels were not significantly elevated and, in some brain regions, were reduced. These results demonstrate that chronic endotoxemia and non-infectious misfolded PrP conformers can independently or synergistically induce key neuropathological hallmarks of prion disease, even in the absence of classical PrP^Sc. Targeting inflammatory signaling and toxic prion intermediates may offer novel therapeutic strategies for prion and prion-like disorders. Full article

Chronic Wasting Disease (CWD) is a prion disease that affects Cervidae species, and is the only known prion disease transmitted among wildlife species. The key pathological feature is the conversion of the normal prion protein (PrP^C) misfolding into abnormal forms (PrP^Sc), triggering the onset of CWD infections. The misfolding can generate distinct PrP^Sc conformations (strains) giving rise to diverse disease phenotypes encompassing pathology, incubation period, and clinical signs. These phenotypes operationally define distinct prion strains, a pivotal element in monitoring CWD spread and zoonotic potential—a complex endeavor compounded by defining and tracking CWD strains. This review pursues a tripartite objective: 1. to address the intricate challenges inherent in ongoing CWD strain classification; 2. to provide an overview of the known CWD-infected isolates, the strains they represent and their passage history; and 3. to describe the spatial diversity of CWD strains in North America, enriching our understanding of CWD strain dynamics. By delving into these dimensions, this review sheds light on the intricate interplay among polymorphisms, biochemical properties, and clinical expressions of CWD. This endeavor aims to elevate the trajectory of CWD research, advancing our insight into prion disease. Full article

Alzheimer’s disease (AD) is the most common cause of dementia worldwide. Pathological deposits of neurotoxin proteins within the brain, such as amyloid-β and hyperphosphorylated tau tangles, are prominent features in AD. The prion protein (PrP) is involved in neurodegeneration via its conversion from the normal cellular form (PrPC) to the infection prion protein scrapie (PrPSc) form. Some studies indicated that post-translationally modified PrPC isoforms play a fundamental role in AD pathological progression. Several studies have shown that the interaction of Aβ oligomers (Aβos) with the N-terminal residues of the PrPC protein region appears critical for neuronal toxicity. PrPC-Aβ binding always occurs in AD brains and is never detected in non-demented controls, and the binding of Aβ aggregates to PrPC is restricted to the N-terminus of PrPC. In this study, we aimed to gather all of the recent information about the connections between PrPC and AD, with potential clinical implications. Full article

Background/Objectives: The normal cellular prion protein (PrP^C) is a cell-surface glycoprotein, mainly localised in neurons of the central nervous system (CNS). The human PRNP gene encodes 253 amino acid residues of precursor PrP^C. Several studies that investigated the role of PRNP and PrP^C in placental mammals, such as humans and mice, failed to reveal its exact function. Methods: In this study, we sequenced and characterised the PRNP gene and PrP^C of the marsupial, P. calura, as a strategy to gain molecular insights into its structure and physicochemical properties. Placentals are separated from marsupials by approximately 125 million years of independent evolution. Results: Standard Western blotting analysis of PrP^C phascogale displayed the typical un-, mono-, and di-glycosylated bands recognized in placentals. Furthermore, we showed that phascogale PRNP gene has two exons, similar to all the marsupials and placentals of the PRNP genes studied. Of note, the phascogale PRNP gene contained distinctive repeats in the PrP^C tail region comparable to the closely related Tasmanian devil (Sarcophilus harrisii) and more distantly related to the grey short-tailed opossum (Monodelphis domestica), common wombat (Vombatus ursinus), and Tammar wallaby (Macropus eugenii); however, its specific composition and numbers were different from placentals. Of importance, comparisons of the phascogale’s PrP^C physicochemical properties with other monotremes, marsupials, and placentals confirmed the Monotremata–Marsupialia–Placentalia evolutionary distance. We found that the protein instability index, a method used to predict the stability of a protein in vivo (Stable: <40; Instable >40), showed that the PrP^C of all marsupials tested, including phascogale, were highly stable compared with the birds, reptiles, amphibians, and fish that were shown to be highly unstable. However, the instability index predicted that all placental species, including human (Homo sapiens), mouse (Mus musculus), bank vole (Myodes glareolus), rhinoceros (Rhinocerotidae), dog (Canis lupus familiaris), flying fox (Pteropus vampyrus), whale (Physeter catodon), cattle (Bos taurus), and sheep (Ovis aries), were either slightly unstable or nearly unstable. Further, our analysis revealed that despite their predicted high PrP^C stability, P. calura exhibited substantial N-terminal disorder (53.76%), while species with highly unstable PrP^Cs based on their instability index, such as Danio rerio, Oryzias latipes, and Astyanax mexicanus, displayed even higher levels of N-terminal disorder (up to 75.84%). These findings highlight a discrepancy between overall predicted stability and N-terminal disorder, suggesting a potential compensatory role of disorder in modulating prion protein stability and function. Conclusions: These results suggest that the high stability of marsupial prion proteins indicates a vital role in maintaining protein homeostasis; however more work is warranted to further depict the exact function. Full article

Prion diseases are fatal neurodegenerative disorders affecting humans and animals, and the central pathogenic event is the conversion of normal prion protein (PrP^C) into the pathogenic PrP^Sc isoform. Previous studies have identified nanobodies that specifically recognize PrP^C and inhibit the PrP^C to PrP^Sc conversion in vitro. In this study, we investigated the potential for in vivo expression of anti-PrP^C nanobodies and evaluated their impact on prion disease. The coding sequences of three nanobodies were packaged into recombinant adeno-associated virus (rAAV) and were administered via intracerebroventricular (ICV) injection in newborn mice. We found that the expression of these nanobodies remained robust for over 180 days, with no observed detrimental effects. To assess their therapeutic potential, we performed ICV injections of nanobody-expressing rAAVs in newborn mice, followed by intracerebral prion inoculation at 5–6 weeks of age. One nanobody exhibited a small yet statistically significant therapeutic effect, extending survival time from 176 days to 184 days. Analyses of diseased brains revealed that the nanobodies did not alter the pathological changes. Our findings suggest that high levels of anti-PrP^C nanobodies are necessary to delay disease progression. Further optimization of the nanobodies, AAV vectors, or delivery methods is essential to achieve a significant therapeutic effect. Full article

Background: In normal prostate cells, receptors for oxytocin (OT), a peptide involved in regulating prostate growth are sequestered within membrane microdomains called caveolae. During cancer progression, polymerase-transcript-release factor (PTRF) is downregulated, caveolae structures are lost and receptors move onto the cell membrane. This study investigated whether proteins responsible for caveolae formation were affected by the OT peptide, also, how OT treatment affected oxytocin receptor (OTR) movement within living cells. Methods: Normal human prostate epithelial cells (PrEC) expressing caveolin and PTRF and androgen-independent (PC3) cancer cells expressing caveolin but not PTRF were used. OTR, caveolin and PTRF expression was determined in human prostate tissue. Results: PTRF expression decreased in tissue alongside an increase in malignancy. Caveolin-1 expression was downregulated by OT treatment. Caveolin-2 was decreased by OT in PrEC cells but increased in PC3 cells. PTRF was decreased by OT in PrEC. TIRF microscopy showed OTR translocated from caveolae to caveolae in normal cells, whereas OTR moved without restraint in malignant cells, possibly stimulating signaling pathways. Conclusions: This study provides evidence for the ability of OT to regulate caveolin and PTRF expression. This study elucidates possible mechanisms by which cell receptors and caveolae proteins interact to enhance cell proliferation. Full article

Prion diseases are fatal neurodegenerative disorders caused by the misfolding of the normal cellular prion protein (PrP^C) into its infectious isoform (PrP^Sc). Although prion diseases in humans, sheep, goats, and cattle have been extensively studied, feline spongiform encephalopathy (FSE) remains poorly understood. Genetic factors, particularly polymorphisms in the prion protein gene (PRNP) and prion-like protein gene (PRND), have been linked to prion disease susceptibility in various species. However, no studies have yet investigated the PRND gene in cats with respect to prion diseases. Therefore, we investigated polymorphisms in the feline PRND gene and analyzed their genetic characteristics. We sequenced the coding region of the PRND gene using samples from 210 domestic cats and determined the genotype and allele frequencies of PRND polymorphisms. We identified thirteen novel single nucleotide polymorphisms (SNPs), including six non-synonymous variants and one insertion/deletion (InDel) in the feline PRND gene. Four of the non-synonymous SNPs were predicted to have deleterious effects on the Doppel protein’s structure and function. Notably, the SNP c.97A>G (I33V) showed potential structural clashes, and the others formed additional hydrogen bonds. The LD analysis revealed strong genetic associations between the PRND SNPs and the PRNP InDel, suggesting linkage between these loci in cats. This study identifies novel PRND polymorphisms in domestic cats and provides new insights into the genetic factors underlying feline susceptibility to prion diseases. The strong genetic linkage between PRND and PRNP polymorphisms, coupled with predictions of detrimental effects on Doppel protein structure, suggests that PRND gene variants could influence prion disease progression in cats. These findings provide a foundational framework for future studies on the functional implications of PRND polymorphisms in FSE. To the best of our knowledge, this study is the first report on the genetic characteristics of PRND polymorphisms in cats. Full article

Chronic wasting disease (CWD) is a prion disease afflicting wild and farmed elk. CWD prions (PrP^Sc) are infectious protein conformations that replicate by inducing a natively expressed prion protein (PrP^C) to refold into the prion conformation. Mass spectrometry was used to study the prions resulting from a previously described experimental inoculation of MM132, ML132, and LL132 elk with a common CWD inoculum. Chymotryptic digestion times and instrument parameters were optimized to yield a set of six peptides, TNMK, MLGSAMSRPL, LLGSAMSRPL, ENMYR, MMER, and VVEQMCITQYQR. These peptides were used to quantify the amount, the M132 and L132 polymorphic composition, and the extent of methionine oxidation of elk PrP^Sc. The amount (ng/g brain tissue) of PrP^Sc present in each sample was determined to be: MM132 (5.4 × 10² ± 7 × 10¹), ML132 (3.3 × 10² ± 6 × 10¹ and 3.6 × 10² ± 3 × 10¹) and LL132 (0.7 × 10² ± 1 × 10¹, 0.2 × 10² ± 0.2 × 10¹, and 0.2 × 10² ± 0.5 × 10¹). The proportion of L132 polymorphism in ML132 (heterozygous) PrP^Sc from CWD-infected elk was determined to be 43% ± 2% or 36% ± 3%. Methionine oxidation was detected and quantified for the M132 and L132 polymorphisms in the samples. In this way, mass spectrometry can be used to characterize prion strains at a molecular level. Full article

Understanding the pathogenesis and mechanisms of prion diseases can significantly expand our knowledge in the field of neurodegenerative diseases. Prion biology is increasingly recognized as being relevant to the pathophysiology of Alzheimer’s disease and Parkinson’s disease, both of which affect millions of people each year. This bioinformatics study used a theoretical protein-RNA recognition code (1-L transcription) to reveal the post-transcriptional regulation of the prion protein (PrP^C). The principle for this method is directly elucidated on PrP^C, in which an octa-repeat can be 1-L transcribed into a GGA triplet repeat RNA aptamer known to reduce the misfolding of normal PrP^C into abnormal PrP^Sc. The identified genes/proteins are associated with mitochondria, cancer, COVID-19 and ER-stress, and approximately half are directly or indirectly associated with prion diseases. For example, the octa-repeat supports CD44, and regions of the brain with astrocytic prion accumulation also display high levels of CD44. Full article

The pathological process of prion diseases implicates that the normal physiological cellular prion protein (PrP^C) converts into misfolded abnormal scrapie prion (PrP^Sc) 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 PrP^C 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. Full article

Prion diseases are a group of deadly neurodegenerative disorders caused by the accumulation of the normal prion protein (PrP^C) into misfolding pathological conformations (PrP^Sc). The PrP gene is essential for the development of prion diseases. Another candidate implicated in prion pathogenesis is the shadow of the prion protein (SPRN) gene. To date, genetic polymorphisms of the SPRN gene and the structure of the Sho protein have not been explored in quails. We used polymerase chain reaction (PCR) to amplify the SPRN gene sequence and then conducted Sanger DNA sequencing to identify the genetic polymorphisms in quail SPRN. Furthermore, we examined the genotype, allele, and haplotype frequencies, and assessed the linkage disequilibrium among the genetic polymorphisms of the SPRN gene in quails. Additionally, we used in silico programs such as MutPred2, SIFT, MUpro, AMYCO, and SODA to predict the pathogenicity of non-synonymous single-nucleotide polymorphisms (SNPs). Alphafold2 predicted the 3D structure of the Sho protein in quails. The results showed that a total of 13 novel polymorphisms were found in 106 quails, including 4 non-synonymous SNPs. Using SIFT and MUpro in silico programs, three out of the four non-synonymous SNPs (A68T, L74P, and M105I) were predicted to have deleterious effects on quail Sho. Furthermore, the 3D structure of quail Sho was predicted to be similar to that of chicken Sho. To our knowledge, this is the first report to investigate the genetic and structural properties of the quail SPRN gene. Full article

The metabolites secreted by probiotics or released after their lysis are called postbiotics. They provide physiological benefits to the host, preventing the colonisation of pathogens by improving the intestinal environment for beneficial commensal bacteria, which reduces the incidence of digestive disorders and improves the immune system. The aim of this work was to evaluate the addition of postbiotics to dairy cow rations during the transition period on nutrient digestibility, composition, and milk yield. The effects of two postbiotics were evaluated in twelve Friesian cows from 30 days before calving to two months of lactation. The animals were randomly allocated to two treatment groups: control (CT) and supplemented with postbiotics (PC and PR). Feeding was ad libitum with 60/40 of forage/concentrate ratio on dry matter basis. Daily feed intake and milk production were recorded individually throughout the study. Two digestibility balances were performed, one before parturition and one after parturition. Colostrum was sampled at first milking and milk was sampled weekly. Data were analysed using a mixed mode in R software 4.4.1. The results suggest that postbiotic supplementation in late gestation and early lactation increase the voluntary intake of dry matter, especially in the PR treatment, with higher apparent total tract digestibility of dry matter, organic matter and neutral detergent fibre. Both treatments including postbiotics induced an increase in colostral immunoglobulin concentration. Milk production of cows receiving the PC treatment was the highest, with high fat and protein yields and a higher persistence of the production curve throughout the lactation. Full article

Prion diseases, also called transmissible spongiform encephalopathies (TSEs), are fatal neurodegenerative diseases characterised by the accumulation of an abnormal prion protein isoform (PrP^Sc: rich in β-sheets—about 30% α-helix and 43% β-sheet), which is converted from the normal prion protein (PrP^C: predominantly α-helical—about 42% α-helix and 3% β-sheet). However, prion disease has not been reported in horses up to now; therefore, horses are known to be a species resistant to prion diseases. Residue S167 in horses has been cited as a critical protective residue for encoding PrP conformational stability in prion-resistance. According to the “protein-only” hypothesis, PrP^Sc is responsible for both the spongiform degeneration of the brain and disease transmissibility. Thus, understanding the conformational dynamics of PrP^Sc from PrP^C is key to developing effective therapies. This article focuses on molecular dynamics and optimization studies on the horse PrP wild type and its S167D mutant, respectively, to understand their conformational dynamics and optimized confirmation; the interesting results will be discussed. Full article