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The cellular prion protein (PrP C ) plays many roles in the developing and adult brain. In addition, PrP C binds to several amyloids in oligomeric and prefibrillar forms and may act as a putative receptor of abnormal misfolded protein species. The role of PrP C in tau seeding and spreading is not known. In the present study, we have inoculated well-characterized sarkosyl-insoluble fractions of sporadic Alzheimer's disease (sAD) into the brain of adult wild-type mice (Prnp +/+ ), Prnp 0/0 (ZH3 strain) mice, and mice over-expressing the secreted form of PrP C lacking their GPI anchor (Tg44 strain). Phospho-tau (ptau) seeding and spreading involving neurons and oligodendrocytes were observed three and six months after inoculation. 3Rtau and 4Rtau deposits from the host tau, as revealed by inoculating Mapt 0/0 mice and by using specific anti-mouse and anti-human tau antibodies suggest modulation of exon 10 splicing of the host mouse Mapt gene elicited by exogenous sAD-tau. However, no tau seeding and spreading differences were observed among Prnp genotypes. Our results show that PrP C does not affect tau seeding and spreading in vivo., (© 2024. The Author(s).)

Introduction: One of the many reasons for cancer treatment failure and recurrence is acquired Multidrug Resistance (MDR). Overcoming cancer drug resistance has been the focus of researchers' studies. Cellular prion protein (PrPC) is a glycophosphatidylinositol-anchored cell-surface glycoprotein that has been implicated in tumor behavior, including proliferation, apoptosis, invasion, metastasis, and chemoresistance. >Method: Lupiwighteone (Lup), a natural isoflavone found in the root of Glycyrrhiza glabra, has anticancer activity against prostate cancer cells, neuroblastoma cells, and human breast cancer cells. However, its pharmacological effects and mechanisms in drug-resistant cancer cells have not been reported. In this study, we used an adriamycin- resistant leukemia K562 cell model, and for the first time, we investigated the reversal effect of Lup on its MDR and the potential mechanism., Result: The results indicated that Lup could induce apoptosis through the mitochondrial pathway while upregulating the expression of related apoptotic proteins, such as Bax, Cyto C, Caspase-3, and PARP1. Autophagy is commonly recognized as a protective mechanism that mediates MDR during treatment. We found that Lup induced cellular autophagy while upregulating the expression of related autophagy proteins such as Beclin 1 and LC3 II., Conclusion: In addition, when Lup was combined with adriamycin, Lup decreased the IC50 of K562/ADR cells; moreover, Lup can downregulate the expression of drug-resistant proteins, suggesting that Lup can reverse drug resistance. Further studies have shown that Lup can downregulate the expression of PrPC-PI3K-Akt axis proteins and PrPC-Oct4 axis proteins. This study demonstrated that Lup has the potential to inhibit the proliferation of K562/ADR cells by targeting PrPC, and further study of the signaling pathway associated with PrPC may provide the experimental basis for the treatment of drug-resistant leukemia., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Oral squamous cell carcinoma (OSCC) is frequently diagnosed at an advanced stage, and the high mortality of patients is mainly due to the delay of diagnosis. Cellular prion protein (PrP C ) contributes to the occurrence and development of many malignant tumors. However, little has been known about the clinical and diagnostic value of PrP C in OSCC. This study investigated the levels of PrP C in the saliva and serum of patients with OSCC, OPMD and control group and their diagnostic value. Methods: The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and Clinical Proteome Tumor Analysis Consortium (CPTAC) databases were analyzed to evaluate the expression of human prion protein gene ( PRNP ) mRNA and PrP C in OSCC. Enzyme-linked Immunosorbent Assay (ELISA) was utilized to detect the expression of PrP C in saliva and serum samples of OSCC, OPMD and control groups. Furthermore, diagnostic value and clinical significance of PrP C in OSCC was identified. Protein-protein interaction (PPI) network was constructed by STRING. GO and KEGG analysis were performed by ClusterProfiler. Results: The levels of PRNP mRNA and PrP C in OSCC were significantly higher than those in the control group from databases ( P <0.05). Besides, salivary and serum PrP C of OSCC patients showed increased levels compared with OPMD and control groups ( P <0.05). The expression of salivary and serum PrP C of OSCC was correlated with the degree of differentiation ( P <0.05), and the expression of PrP C from CPTAC was related to tumor stage of OSCC ( P <0.05). The areas under the diagnostic curves (AUCs) of salivary and serum PrP C were 0.807 and 0.671, respectively. GO and KEGG analysis revealed that PrP C might be related to cell adhesion, cell differentiation, signal transduction and apoptosis, and participate in the pathways of focal adhesion, PI3K-Akt signaling pathway and ECM- receptor interaction in OSCC. Conclusion: PrP C in saliva and serum may be a potential biomarker for early diagnosis of OSCC., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: Twitter is a common platform for people to share opinions, discuss health-related topics, and engage in conversations with a wide audience. Twitter users frequently share health information related to chronic diseases, mental health, and general wellness topics. However, sharing health information on Twitter raises privacy concerns as it involves sharing personal and sensitive data on a web-based platform., Objective: This study aims to adopt an interactive approach and develop a model consisting of privacy concerns related to web-based vendors and web-based peers. The research model integrates the 4 dimensions of concern for information privacy that express concerns related to the practices of companies and the 4 dimensions of peer privacy concern that reflect concerns related to web-based interactions with peers. This study examined how this interaction may affect individuals' information-sharing behavior on Twitter., Methods: Data were collected from 329 Twitter users in the United States using a web-based survey., Results: Results suggest that privacy concerns related to company practices might not significantly influence the sharing of general health information, such as details about hospitals and medications. However, privacy concerns related to companies and third parties can negatively shape the disclosure of specific health information, such as personal medical issues (β=-.43; P<.001). Findings show that peer-related privacy concerns significantly predict sharing patterns associated with general (β=-.38; P<.001) and specific health information (β=-.72; P<.001). In addition, results suggest that people may disclose more general health information than specific health information owing to peer-related privacy concerns (t 165 =4.72; P<.001). The model explains 41% of the variance in general health information disclosure and 67% in specific health information sharing on Twitter., Conclusions: The results can contribute to privacy research and propose some practical implications. The findings provide insights for developers, policy makers, and health communication professionals about mitigating privacy concerns in web-based health information sharing. It particularly underlines the importance of addressing peer-related privacy concerns. The study underscores the need to build a secure and trustworthy web-based environment, emphasizing the significance of peer interactions and highlighting the need for improved regulations, clear data handling policies, and users' control over their own data., (©Pouyan Esmaeilzadeh. Originally published in JMIR Formative Research (https://formative.jmir.org), 12.01.2024.)

Introduction: Infection with human T cell lymphotropic virus type 1 (HTLV-1) is endemic in Brazil and is linked with pro-inflammatory conditions including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic neuroinflammatory incapacitating disease that culminates in loss of motor functions. The mechanisms underlying the onset and progression of HAM/TSP are incompletely understood. Previous studies have demonstrated that inflammation and infectious agents can affect the expression of cellular prion protein (PrP C ) in immune cells., Methods: Here, we investigated whether HTLV-1 infection affected PrP C content in cell lines and primary CD4 + cells in vitro using flow cytometry and western blot assays., Results: We found that HTLV-1 infection decreased the expression levels of PrP C and HTLV-1 Orf I encoded p12, an endoplasmic reticulum resident protein also known to affect post-transcriptionally cellular proteins such as MHC-class I and the IL-2 receptor. In addition, we observed a reduced percentage of CD4 + T cells from infected individuals expressing PrP C , which was reflected by IFN type II but not IL-17 expression., Discussion: These results suggested that PrP C downregulation, linked to both HTLV-1 p12 and IFN-γ expression in CD4 + cells, may play a role in the neuropathogenesis of HTLV-1 infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright At least a portion of this work is authored by Isabela Silva De Castro, Cynthia A. Pise-Masison and Genoveffa Franchini on behalf of the U.S. Government and as regards Dr. Silva De Castro, Dr. Pise-Masison and Dr. Franchini and the U.S. Government, is not subject to copyright protection in the United States. Foreign and other copyrights may apply.)

In this study, we compared the heat tolerance parameter (D 65℃ ) values of Salmonella enterica serovar Enteritidis PT 30 (S. Enteritidis ) heat adapted at different degrees (at 42 ℃ for 20-180 min) and cultivated using two methods. The treated group with the highest D 65℃ value (LP-42 ℃-60 min) and the untreated groups (Control-TSB and Control-TSA) were subjected to transcriptome analysis. Heat-adaptation increased the D 65℃ values of S. Enteritidis by 24.5-60.8%. The D 65℃ values of the LP-42 ℃-60 min group (1.85 ± 0.13 min, 7.7% higher) was comparable to that of the Control-TSA. A total of 483 up- and 443 downregulated genes of S. enteritidis were identified in the LP-42 ℃-60 min group (log 2 fold change > 1, adjusted p-value < 0.05). Among these genes, 5 co-expressed and 15 differentially expressed genes in the LP-42 ℃-60 min and Control-TSA grops possibly contributed to the high D 65℃ values of S. Enteritidis . The Rpo regulon was involved in the heat adaptation of S. Enteritidis , as evidenced by the significant upregulation of rpoS, rpoN, and rpoE. KEGG enrichment pathways, such as biosynthesis of secondary metabolites, tricarboxylic acid, and ribosomes were identified and mapped to reveal the molecular mechanisms of S. enteritidis during heat adaptation. This study quantified the enhanced heat tolerance of S. Enteritidis heat adapted at different degrees of heat-adaptation. The results of this study may serve as a basis for elucidating the molecular mechanisms underlying the enhanced heat tolerance at the transcriptome level., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The properties of infectious prions and the pathology of the diseases they cause are dependent upon the unique conformation of each prion strain. How the pathology of prion disease correlates with different strains and genetic backgrounds has been investigated via in vivo assays, but how interactions between specific prion strains and cell types contribute to the pathology of prion disease has been dissected more effectively using in vitro cell lines. Observations made through in vivo and in vitro assays have informed each other with regard to not only how genetic variation influences prion properties, but also how infectious prions are taken up by cells, modified by cellular processes and propagated, and the cellular components they rely on for persistent infection. These studies suggest that persistent cellular infection results from a balance between prion propagation and degradation. This balance may be shifted depending upon how different cell lines process infectious prions, potentially altering prion stability, and how fast they can be transported to the lysosome. Thus, in vitro studies have given us a deeper understanding of the interactions between different prions and cell types and how they may influence prion disease phenotypes in vivo., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

The prion protein (PrP C ) is subjected to several conserved endoproteolytic events producing bioactive fragments that are of increasing interest for their physiological functions and their implication in the pathogenesis of prion diseases and other neurodegenerative diseases. However, systematic and comprehensive investigations on the full spectrum of PrP C proteoforms have been hampered by the lack of methods able to identify all PrP C -derived proteoforms. Building on previous knowledge of PrP C endoproteolytic processing, we thus developed an optimized Western blot assay able to obtain the maximum information about PrP C constitutive processing and the relative abundance of PrP C proteoforms in a complex biological sample. This approach led to the concurrent identification of the whole spectrum of known endoproteolytic-derived PrP C proteoforms in brain homogenates, including C-terminal, N-terminal and, most importantly, shed PrP C -derived fragments. Endoproteolytic processing of PrP C was remarkably similar in the brain of widely used wild type and transgenic rodent models, with α-cleavage-derived C1 representing the most abundant proteoform and ADAM10-mediated shedding being an unexpectedly prominent proteolytic event. Interestingly, the relative amount of shed PrP C was higher in WT mice than in most other models. Our results indicate that constitutive endoproteolytic processing of PrP C is not affected by PrP C overexpression or host factors other than PrP C but can be impacted by PrP C primary structure. Finally, this method represents a crucial step in gaining insight into pathophysiological roles, biomarker suitability, and therapeutic potential of shed PrP C and for a comprehensive appraisal of PrP C proteoforms in therapies, drug screening, or in the progression of neurodegenerative diseases., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Cellular prion protein (PrP C ) is a highly conserved glycoprotein, present both anchored in the cell membrane and soluble in the extracellular medium. It has a diversity of ligands and is variably expressed in numerous tissues and cell subtypes, most notably in the central nervous system (CNS). Its importance has been brought to light over the years both under physiological conditions, such as embryogenesis and immune system homeostasis, and in pathologies, such as cancer and neurodegenerative diseases. During development, PrP C plays an important role in CNS, participating in axonal growth and guidance and differentiation of glial cells, but also in other organs such as the heart, lung, and digestive system. In diseases, PrP C has been related to several types of tumors, modulating cancer stem cells, enhancing malignant properties, and inducing drug resistance. Also, in non-neoplastic diseases, such as Alzheimer's and Parkinson's diseases, PrP C seems to alter the dynamics of neurotoxic aggregate formation and, consequently, the progression of the disease. In this review, we explore in detail the multiple functions of this protein, which proved to be relevant for understanding the dynamics of organism homeostasis, as well as a promising target in the treatment of both neoplastic and degenerative diseases., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Cancer stem cells (CSCs) are a subpopulation of cancer cells that drive tumour progression and metastasis. Anti-CSC strategies represent new targets for cancer therapies. However, CSCs are highly plastic and heterogeneous, making validation and targeting difficult without bona fide markers that define their identity, especially in a clinical setting. Here, we report that a leucine-rich repeat containing G protein-coupled receptor 4 (LGR4) cooperates with CD44 and PrPc; the latter contributes significantly to metastatic capacity and defines the stemness characteristics of colorectal CSCs. CD44 + PrPc + LGR4 + cells effectively developed into organoids and, when transplanted, generated orthotopic and metastatic tumours. Importantly, targeting LGR4 and PrPc with lentiviral shRNAs inhibited organoid development and the growth of orthotopic tumours by inhibiting Wnt/β-catenin signalling. Thus, our study offers a novel therapeutic strategy that simultaneously targets CSC stemness and metastatic properties., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Amyloid-β (Aβ) oligomers induce the overproduction of phosphorylated tau and neurodegeneration. These cascades gradually cause cognitive impairment in Alzheimer's disease (AD). While each pathological event in AD has been studied in detail separately, the spatial and temporal relationships between pathological events in AD remain unclear., Objective: We demonstrated that lipid rafts function as a common platform for the pathological cascades of AD., Methods: Cellular and synaptosomal lipid rafts were prepared from the brains of Aβ amyloid model mice (Tg2576 mice) and double transgenic mice (Tg2576 x TgTauP301L mice) and longitudinally analyzed., Results: Aβ dimers, the cellular prion protein (PrPc), and Aβ dimer/PrPc complexes were detected in the lipid rafts. The levels of Fyn, the phosphorylated NR2B subunit of the N-methyl-D-aspartate receptor, glycogen synthase kinase 3β, total tau, phosphorylated tau, and tau oligomers increased with Aβ dimer accumulation in both the cellular and synaptosomal lipid rafts. Increases in the levels of these molecules were first seen at 6 months of age and corresponded with the early stages of Aβ accumulation in the amyloid model mice., Conclusion: Lipid rafts act as a common platform for the progression of AD pathology. The findings of this study suggest a novel therapeutic approach to AD, involving the modification of lipid raft components and the inhibition of their roles in the sequential pathological events of AD.

Cellular protein homeostasis (proteostasis) requires an accurate balance between protein biosynthesis, folding, and degradation, and its instability is causally related to human diseases and cancers. Here, we created numerous engineered cancer cell lines targeting APP (amyloid ß precursor protein) and/or PRNP (cellular prion) genes and we showed that APP knocking-down impaired PRNP mRNA level and vice versa, suggesting a link between their gene regulation. PRNP KD , APP KD and PRNP KD /APP KD HeLa cells encountered major difficulties to grow in a 3D tissue-like environment. Unexpectedly, we found a cytoplasmic accumulation of the PrP c protein without PRNP gene up regulation, in both APP KD and APP KO HeLa cells. Interestingly, APP and/or PRNP gene ablation enhanced the chaperone/serine protease HTRA2 gene expression, which is a protein processing quality factor involved in Alzheimer's disease. Importantly, HTRA2 gene silencing decreased PRNP mRNA level and lowered PrP c protein amounts, and conversely, HTRA2 overexpression increased PRNP gene regulation and enhanced membrane-anchored and cytoplasmic PrP c fractions. PrP c , APP and HTRA2 destabilized membrane-associated CD24 protein, suggesting changes in the lipid raft structure. Our data show for the first time that APP and the dual chaperone/serine protease HTRA2 protein could modulate PrP c proteostasis hampering cancer cell behavior., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Alzheimer's disease (AD) is the main cause of dementia, and β-amyloid (Aβ) is a central factor in the initiation and progression of the disease. Different forms of Aβ have been identified as monomers, oligomers, and amyloid fibrils. Many proteins have been implicated as putative receptors of respective forms of Aβ. Distinct forms of Aβ oligomers are considered to be neurotoxic species that trigger the pathophysiology of AD. It was reported that cellular prion protein (PrP C ) is one of the most selective and high-affinity binding partners of Aβ oligomers. The interaction of Aβ oligomers with PrP C is important to synaptic dysfunction and loss. The binding of Aβ oligomers to PrP C has mostly been studied with synthetic peptides, cell culture, and murine models of AD by biochemical and biological methods. However, the molecular mechanisms underlying the relationship between Aβ oligomers and PrP C remain unclear, especially in the human brain. We immunohistochemically investigated the relationship between Aβ oligomers and PrP C in human brain tissue with and without amyloid pathology. We histologically demonstrate that PrP C accumulates with aging in human brain tissue even prior to AD mainly within diffuse-type amyloid plaques, which are composed of more soluble Aβ oligomers without stacked β-sheet fibril structures. Our results suggest that PrP C accumulating plaques are associated with more soluble Aβ oligomers, and appear even prior to AD. The investigation of PrP C accumulating plaques may provide new insights into AD., (© 2021 The Authors. Brain Pathology published by John Wiley & Sons Ltd on behalf of International Society of Neuropathology.)

Cytoplasmic aggregation of the primarily nuclear TAR DNA-binding protein 43 (TDP-43) affects neurons in most amyotrophic lateral sclerosis (ALS) and approximately half of frontotemporal lobar degeneration (FTLD) cases. The cellular prion protein, PrP C , has been recognized as a common receptor and downstream effector of circulating neurotoxic species of several proteins involved in neurodegeneration. Here, capitalizing on our recently adapted TDP-43 real time quaking induced reaction, we set reproducible protocols to obtain standardized preparations of recombinant TDP-43 fibrils. We then exploited two different cellular systems (human SH-SY5Y and mouse N2a neuroblastoma cells) engineered to express low or high PrP C levels to investigate the link between PrP C expression on the cell surface and the internalization of TDP-43 fibrils. Fibril uptake was increased in cells overexpressing either human or mouse prion protein. Increased internalization was associated with detrimental consequences in all PrP-overexpressing cell lines but was milder in cells expressing the human form of the prion protein. As described for other amyloids, treatment with TDP-43 fibrils induced a reduction in the accumulation of the misfolded form of PrP C , PrP Sc , in cells chronically infected with prions. Our results expand the list of misfolded proteins whose uptake and detrimental effects are mediated by PrP C , which encompass almost all pathological amyloids involved in neurodegeneration.

In prion diseases, the spread of infectious prions (PrPSc) is thought to occur within nerves and across synapses of the central nervous system (CNS). However, the mechanisms by which PrPSc moves within axons and across nerve synapses remain undetermined. Molecular motors, including kinesins and dyneins, transport many types of intracellular cargo. Kinesin-1C (KIF5C) has been shown to transport vesicles carrying the normal prion protein (PrPC) within axons, but whether KIF5C is involved in PrPSc axonal transport is unknown. The current study tested whether stereotactic inoculation in the striatum of KIF5C knock-out mice ( Kif5c -/- ) with 0.5 µL volumes of mouse-adapted scrapie strains 22 L or ME7 would result in an altered rate of prion spreading and/or disease timing. Groups of mice injected with each strain were euthanized at either pre-clinical time points or following the development of prion disease. Immunohistochemistry for PrP was performed on brain sections and PrPSc distribution and tempo of spread were compared between mouse strains. In these experiments, no differences in PrPSc spread, distribution or survival times were observed between C57BL/6 and Kif5c -/- mice.

Background/aim: Studies have reported that the expression of c-Met and PrP C improves tumor progression. However, not much is known about their relationship. We hypothesized that c-Met and PrP C interact with each other, and enhance cancer stem cell (CSC) characteristics., Materials and Methods: Magnetic activated cell sorting was used to examine the interaction between c-Met and PrP C The effects of the interaction on downstream signals, stem cell marker expression, and sphere formation of colorectal cancer (CRC) cells were investigated., Results: We demonstrated the increased expression and binding levels of c-Met and PrP C in CRC cells compared to normal colon epithelial cells. We revealed that the c-Met and PrP C interaction induced the ERK activation and Oct4 upregulation. The inhibition of c-Met by crizotinib reduced ERK activation and Oct4 expression and suppressed CSC properties., Conclusion: c-Met and PrP C interact with each other, and targeting c-Met using crizotinib could be a powerful strategy for CRC therapy., (Copyright © 2021 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

A cellular prion protein (PrP C ) is a ubiquitous cell surface glycoprotein, and its physiological functions have been receiving increased attention. Endogenous PrP C is present in various kidney tissues and undergoes glomerular filtration. In prion diseases, abnormal prion proteins are found to accumulate in renal tissues and filtered into urine. Urinary prion protein could serve as a diagnostic biomarker. PrP C plays a role in cellular signaling pathways, reno-protective effects, and kidney iron uptake. PrP C signaling affects mitochondrial function via the ERK pathway and is affected by the regulatory influence of microRNAs, small molecules, and signaling proteins. Targeting PrP C in acute and chronic kidney disease could help improve iron homeostasis, ameliorate damage from ischemia/reperfusion injury, and enhance the efficacy of mesenchymal stem/stromal cell or extracellular vesicle-based therapeutic strategies. PrP C may also be under the influence of BMP/Smad signaling and affect the progression of TGF-β-related renal fibrosis. PrP C conveys TNF-α resistance in some renal cancers, and therefore, the coadministration of anti-PrP C antibodies improves chemotherapy. PrP C can be used to design antibody-drug conjugates, aptamer-drug conjugates, and customized tissue inhibitors of metalloproteinases to suppress cancer. With preclinical studies demonstrating promising results, further research on PrP C in the kidney may lead to innovative PrP C -based therapeutic strategies for renal disease.

Background: High-density oligomers of the prion protein (HDPs) have previously been identified in brain tissues of patients with rapidly progressive Alzheimer's disease (rpAD). The current investigation aims at identifying interacting partners of HDPs in the rpAD brains to unravel the pathological involvement of HDPs in the rapid progression., Methods: HDPs from the frontal cortex tissues of rpAD brains were isolated using sucrose density gradient centrifugation. Proteins interacting with HDPs were identified by co-immunoprecipitation coupled with mass spectrometry. Further verifications were carried out using proteomic tools, immunoblotting, and confocal laser scanning microscopy., Results: We identified rpAD-specific HDP-interactors, including the growth arrest specific 2-like 2 protein (G2L2). Intriguingly, rpAD-specific disturbances were found in the localization of G2L2 and its associated proteins i.e., the end binding protein 1, α-tubulin, and β-actin., Discussion: The results show the involvement of HDPs in the destabilization of the neuronal actin/tubulin infrastructure. We consider this disturbance to be a contributing factor for the rapid progression in rpAD.

Anticancer drugs, such as fluorouracil (5-FU), oxaliplatin, and doxorubicin (Dox) are commonly used to treat colorectal cancer (CRC); however, owing to their low response rate and adverse effects, the development of efficient drug delivery systems (DDSs) is required. The cellular prion protein PrP C , which is a cell surface glycoprotein, has been demonstrated to be overexpressed in CRC, however, there has been no research on the development of PrP C -targeting DDSs for targeted drug delivery to CRC. In this study, PrP C aptamer (Apt)-conjugated gold nanoparticles (AuNPs) were synthesized for targeted delivery of Dox to CRC. Thiol-terminated PrP C -Apt was conjugated to AuNPs, followed by hybridization of its complementary DNA for drug loading. Finally, Dox was loaded onto the AuNPs to synthesize PrP C -Apt-functionalized doxorubicin-oligomer-AuNPs (PrP C -Apt DOA). The PrP C -Apt DOA were spherical nanoparticles with an average diameter of 20 nm. Treatment of CRC cells with PrP C -Apt DOA induced reactive oxygen species generation by decreasing catalase and superoxide dismutase activities. In addition, treatment with PrP C -Apt DOA inhibited mitochondrial functions by decreasing the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha, complex 4 activity, and oxygen consumption rates. Compared to free Dox, PrP C -Apt DOA decreased proliferation and increased apoptosis of CRC cells to a greater degree. In this study, we demonstrated that PrP C -Apt DOA targeting could effectively deliver Dox to CRC cells. PrP C -Apt DOA can be used as a treatment for CRC, and have the potential to replace existing anticancer drugs, such as 5-FU, oxaliplatin, and Dox.

Alzheimer's disease (AD) is a chronic neurodegenerative disease that has been recognized as one of the most intractable medical problems with heavy social and economic costs. Amyloid-β (Aβ) has been identified as a major factor that participates in AD progression through its neurotoxic effects. The major mechanism of Aβ-induced neurotoxicity is by interacting with membrane receptors and subsequent triggering of aberrant cellular signaling. Besides, Aβ transporters also plays an important role by affecting Aβ homeostasis. Thus, these Aβ receptors and transporters are potential targets for the development of AD therapies. Here, we summarize the reported therapeutic strategies targeting Aβ receptors and transporters to provide a molecular basis for future rational design of anti-AD agents.

Studies on the cellular prion protein (PrP C ) have been actively conducted because misfolded PrP C is known to cause transmissible spongiform encephalopathies or prion disease. PrP C is a glycophosphatidylinositol-anchored cell surface glycoprotein that has been reported to affect several cellular functions such as stress protection, cellular differentiation, mitochondrial homeostasis, circadian rhythm, myelin homeostasis, and immune modulation. Recently, it has also been reported that PrP C mediates tumor progression by enhancing the proliferation, metastasis, and drug resistance of cancer cells. In addition, PrP C regulates cancer stem cell properties by interacting with cancer stem cell marker proteins. In this review, we summarize how PrP C promotes tumor progression in terms of proliferation, metastasis, drug resistance, and cancer stem cell properties. In addition, we discuss strategies to treat tumors by modulating the function and expression of PrP C via the regulation of HSPA1L/HIF-1α expression and using an anti-prion antibody.

Cellular prion protein (PrPC) is a plasma membrane glycophosphatidylinositol-anchored protein and it is involved in multiple functions, including neuroprotection and oxidative stress. So far, most of the PrPC functional research is done in neuronal tissue or cell lines; the role of PrPC in non-neuronal tissues such as liver is only poorly understood. To characterize the role of PrPC in the liver, a proteomics approach was applied in the liver tissue of PrPC knockout mice. The proteome analysis and biochemical validations showed an excessive fat accumulation in the liver of PrPC knockout mice with a change in mRNA expression of genes linked to lipid metabolism. In addition, the higher Bax to Bcl2 ratio, up-regulation of tgfb1 mRNA expression in PrPC knockout mice liver, further showed the evidences of metabolic disease. Over-expression of PrPC in fatty acid-treated AML12 hepatic cell line caused a reduction in excessive intracellular fat accumulation; shows association of PrPC levels and lipid metabolism. Therefore, based on observation of excessive fat globules in the liver of ageing PrPC knockout mice and the reduction of fat accumulation in AML12 cell line with PrPC over-expression, the role of PrPC in lipid metabolism is described.

The mobility of cellular prion protein (PrP C ) in specific cell membrane domains and among distinct cell compartments dictates its molecular interactions and directs its cell function. PrP C works in concert with several partners to organize signaling platforms implicated in various cellular processes. The scaffold property of PrP C is able to gather a molecular repertoire to create heterogeneous membrane domains that favor endocytic events. Dynamic trafficking of PrP C through multiple pathways, in a well-orchestrated mechanism of intra and extracellular vesicular transport, defines its functional plasticity, and also assists the conversion and spreading of its infectious isoform associated with neurodegenerative diseases. In this review, we highlight how PrP C traffics across intra- and extracellular compartments and the consequences of this dynamic transport in governing cell functions and contributing to prion disease pathogenesis.

Cellular prion protein (PrP C ) is a widely expressed glycosylphosphatidylinositol-anchored membrane protein. Scrapie prion protein is a misfolded and aggregated form of PrP C responsible for prion-induced neurodegenerative diseases. Understanding the function of the nonpathogenic PrP C monomer is an important objective. PrP C may be shed from the cell surface to generate soluble derivatives. Herein, we studied a recombinant derivative of PrP C (soluble cellular prion protein, S-PrP) that corresponds closely in sequence to a soluble form of PrP C shed from the cell surface by proteases in the A Disintegrin And Metalloprotease (ADAM) family. S-PrP activated cell-signaling in PC12 and N2a cells. TrkA was transactivated by Src family kinases and extracellular signal-regulated kinase 1/2 was activated downstream of Trk receptors. These cell-signaling events were dependent on the N -methyl-d-aspartate receptor (NMDA-R) and low-density lipoprotein receptor-related protein-1 (LRP1), which functioned as a cell-signaling receptor system in lipid rafts. Membrane-anchored PrP C and neural cell adhesion molecule were not required for S-PrP-initiated cell-signaling. S-PrP promoted PC12 cell neurite outgrowth. This response required the NMDA-R, LRP1, Src family kinases, and Trk receptors. In Schwann cells, S-PrP interacted with the LRP1/NMDA-R system to activate extracellular signal-regulated kinase 1/2 and promote cell migration. The effects of S-PrP on PC12 cell neurite outgrowth and Schwann cell migration were similar to those caused by other proteins that engage the LRP1/NMDA-R system, including activated α 2 -macroglobulin and tissue-type plasminogen activator. Collectively, these results demonstrate that shed forms of PrP C may exhibit important biological activities in the central nervous system and the peripheral nervous system by serving as ligands for the LRP1/NMDA-R system., Competing Interests: Conflict of interest—The authors declare that they have no conflicts of interest with the contents of this article., (© 2020 Mantuano et al.)

Background/aim: Cancer stem cell characteristics and drug resistance of colorectal cancer are associated with failure of cancer treatment. In this study, we investigated the effects of PrP C on cancer stem cell characteristics, migration, invasion, and drug resistance of 5FU-resistant CRC cells., Materials and Methods: PrP C negative and PrP C positive cells were isolated from 5FU-resistant CRC cells using magnetic activated cell sorting. Sphere formation, cancer stem cell marker expression, migration, invasion, and drug resistance were analyzed., Results: PrP C positive cells showed increased sphere formation capacity and increased expression of cancer stem cell markers compared to PrP C negative cells. In addition, PrP C positive cells showed increased migration, invasion and drug resistance compared to PrP C negative cells. Furthermore, knockdown of PrP C abolished these effects., Conclusion: PrP C expression is important in CRC cell behavior, such as sphere formation, migration, invasion, and drug resistance. PrP C is an important therapeutic target for the treatment of CRC., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Myelin is a dynamic membrane that is important for coordinating the fast propagation of action potentials along small or large caliber axons (0.1-10 μm) some of which extend the entire length of the spinal cord. Due to the heterogeneity of electrical and energy demands of the variable neuronal populations, the axo-myelinic and axo-glial interactions that regulate the biophysical properties of myelinated axons also vary in terms of molecular interactions at the membrane interfaces. An important topic of debate in neuroscience is how myelin is maintained and modified under neuronal control and how disruption of this control (due to disease or injury) can initiate and/or propagate neurodegeneration. One of the key molecular signaling cascades that have been investigated in the context of neural injury over the past two decades involves the myelin-associated inhibitory factors (MAIFs) that interact with Nogo receptor 1 (NgR1). Chief among the MAIF superfamily of molecules is a reticulon family protein, Nogo-A, that is established as a potent inhibitor of neurite sprouting and axon regeneration. However, an understated role for NgR1 is its ability to control axo-myelin interactions and Nogo-A specific ligand binding. These interactions may occur at axo-dendritic and axo-glial synapses regulating their functional and dynamic membrane domains. The current review provides a comprehensive analysis of how neuronal NgR1 can regulate myelin thickness and plasticity under normal and disease conditions. Specifically, we discuss how NgR1 plays an important role in regulating paranodal and juxtaparanodal domains through specific signal transduction cascades that are important for microdomain molecular architecture and action potential propagation. Potential therapeutics designed to target NgR1-dependent signaling during disease are being developed in animal models since interference with the involvement of the receptor may facilitate neurological recovery. Hence, the regulatory role played by NgR1 in the axo-myelinic interface is an important research field of clinical significance that requires comprehensive investigation., (Copyright © 2020 Petratos, Theotokis, Kim, Azari and Lee.)

Introduction: Prion diseases are rare and fatal neurodegenerative disorders. The key molecular event in these disorders is the misfolding of the physiological form of the cellular prion protein, PrP C , leading to the accumulation of a pathological isoform, PrP Sc , with unique features. Both isoforms share the same primary sequence, lacking detectable differences in posttranslational modification, a major hurdle for their biochemical or biophysical independent characterization. The mechanism underlying the conversion of PrP C to PrP Sc is not completely understood, so finding an effective therapy to cure prion disorders is extremely challenging., Areas Covered: This review discusses the strategies for decreasing prion replication and throws a spotlight on the relevance of PrP C in the prion accumulation process., Expert Opinion: PrP C is the key substrate for prion pathology; hence, the most promising therapeutic approach appears to be the targeting of PrP C to block the production of the infectious isoform. The use of RNA interference and antisense oligonucleotide technologies may offer opportunities for treatment because of their success in clinical trials for other neurodegenerative diseases.

The cellular prion protein (PrP C ) comprises two domains: a globular C-terminal domain and an unstructured N-terminal domain. Recently, copper has been observed to drive tertiary contact in PrP C , inducing a neuroprotective cis interaction that structurally links the protein's two domains. The location of this interaction on the C terminus overlaps with the sites of human pathogenic mutations and toxic antibody docking. Combined with recent evidence that the N terminus is a toxic effector regulated by the C terminus, there is an emerging consensus that this cis interaction serves a protective role, and that the disruption of this interaction by misfolded PrP oligomers may be a cause of toxicity in prion disease. We demonstrate here that two highly conserved histidines in the C-terminal domain of PrP C are essential for the protein's cis interaction, which helps to protect against neurotoxicity carried out by its N terminus. We show that simultaneous mutation of these histidines drastically weakens the cis interaction and enhances spontaneous cationic currents in cultured cells, the first C-terminal mutant to do so. Whereas previous studies suggested that Cu 2+ coordination was localized solely to the protein's N-terminal domain, we find that both domains contribute equatorially coordinated histidine residue side-chains, resulting in a novel bridging interaction. We also find that extra N-terminal histidines in pathological familial mutations involving octarepeat expansions inhibit this interaction by sequestering copper from the C terminus. Our findings further establish a structural basis for PrP C 's C-terminal regulation of its otherwise toxic N terminus., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) plaque and neurofibrillary tangle formation, respectively. Neurofibrillary tangles form as a result of the intracellular accumulation of hyperphosphorylated tau. Telomerase activity and levels of the human reverse transcriptase (hTERT) subunit of telomerase are significantly decreased in AD. Recently, it has been demonstrated that the 37 kDa/67 kDa laminin receptor (LRP/LR) interacts with telomerase and is implicated in Aβ pathology. Since both LRP/LR and telomerase are known to play a role in the Aβ facet of AD, we hypothesized that they might also play a role in tauopathy., Objective: This study aimed to determine if LRP/LR has a relationship with tau and whether overexpression of LRP::FLAG has an effect on tauopathy-related proteins., Methods: We employed confocal microscopy and FRET to determine whether LRP/LR and tau co-localize and interact. LRP::FLAG overexpression in HEK-293 and SH-SY5Y cells as well as analysis of tauopathy-related proteins was assessed by western blotting., Results: We demonstrate that LRP/LR co-localizes with tau in the perinuclear cell compartment and confirmed a direct interaction between LRP/LR and tau in HEK-293 cells. Overexpression of LRP::FLAG in HEK-293 and SH-SY5Y cells decreased total and phosphorylated tau levels with a concomitant decrease in PrPc levels, a tauopathy-related protein. LRP::FLAG overexpression also resulted in increased hTERT levels., Conclusion: This data suggest that LRP/LR extends its role in AD through a direct interaction with tau, and recommend LRP::FLAG as a possible alternative AD therapeutic via decreasing phosphorylated tau levels.

The vast majority of therapeutic approaches tested so far for prion diseases, transmissible neurodegenerative disorders of human and animals, tackled PrP Sc , the aggregated and infectious isoform of the cellular prion protein (PrP C ), with largely unsuccessful results. Conversely, targeting PrP C expression, stability or cell surface localization are poorly explored strategies. We recently characterized the mode of action of chlorpromazine, an anti-psychotic drug known to inhibit prion replication and toxicity by inducing the re-localization of PrP C from the plasma membrane. Unfortunately, chlorpromazine possesses pharmacokinetic properties unsuitable for chronic use in vivo, namely low specificity and high toxicity. Here, we employed HEK293 cells stably expressing EGFP-PrP to carry out a semi-automated high content screening (HCS) of a chemical library directed at identifying non-cytotoxic molecules capable of specifically relocalizing PrP C from the plasma membrane as well as inhibiting prion replication in N2a cell cultures. We identified four candidate hits inducing a significant reduction in cell surface PrP C , one of which also inhibited prion propagation and toxicity in cell cultures in a strain-independent fashion. This study defines a new screening method and novel anti-prion compounds supporting the notion that removing PrP C from the cell surface could represent a viable therapeutic strategy for prion diseases., (© 2019 International Society for Neurochemistry.)

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) that affects members of the cervidae family. The infectious agent is a misfolded isoform (PrP SC ) of the host prion protein (PrP C ). The replication of PrP SC initiates a cascade of developmental changes that spread from cell to cell, individual to individual, and that for some TSEs, has crossed the species barrier. CWD can be transmitted horizontally and vertically, and it is the only TSE that affects free-ranging wildlife. While other TSEs are under control and even declining, infection rates of CWD continue to grow and the disease distribution continues to expand in North America and around the world. Since the first reported case in 1967, CWD has spread infecting captive and free-ranging cervids in 26 states in the US, 3 Canadian provinces, 3 European countries and has been found in captive cervids in South Korea. CWD causes considerable ecologic, economic and sociologic impact, as this is a 100% fatal highly contagious infectious disease, with no treatment or cure available. Because some TSEs have crossed the species barrier, the zoonotic potential of CWD is a concern for human health and continues to be investigated. Here we review the characteristics of the CWD prion protein, mechanisms of transmission and the role of genetics. We discuss the characteristics that contribute to prevalence and distribution. We also discuss the impact of CWD and review the management strategies that have been used to prevent and control the spread of CWD., Competing Interests: Nelda A Rivera and Nohra E Mateus-Pinilla report grants from the US Fish and Wildlife Service Federal Aid in Wildlife Restoration Project (W-146-R) during the conduct of the study. The authors report no other conflicts of interest in this work., (© 2019 Rivera et al.)

The conversion of the normal cellular prion protein (PrP C ) to the misfolded pathogenic scrapie prion protein (PrP Sc ) is the biochemical hallmark of prion replication. So far, various chemical compounds that inhibit this conformational conversion have been identified. Here, we report the novel anti-prion activity of SGI-1027 and its meta/meta analogue (M/M), previously known only as potent inhibitors of DNA methyltransferases (DNMTs). These compounds effectively decreased the level of PrP Sc in cultured cells with permanent prion infection, without affecting PrP C at the transcriptional or translational levels. Furthermore, SGI-1027 prevented effective prion infection of the cells. In a PrP aggregation assay, both SGI-1027 and M/M blocked the formation of misfolded PrP aggregates, implying that binding of these compounds hinders the PrP conversion process. A series of binding and docking analyses demonstrated that both SGI-1027 and M/M directly interacted with the C-terminal globular domain of PrP C , but only SGI-1027 bound to a specific region of PrP C with high affinity, which correlates with its potent anti-prion efficacy. Therefore, we report SGI-1027 and related compounds as a novel class of potential anti-prion agents that preferentially function through direct interaction with PrP C ., (© 2019 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V.)

The cellular prion protein (PrP C ) is a glycoprotein that is processed through several proteolytic pathways. Modulators of PrP C proteolysis are of interest because full-length PrP C and its cleavage fragments differ in their propensity to misfold, a process that plays a key role in the pathogenesis of prion diseases. PrP C may also act as a receptor for neurotoxic, oligomeric species of other proteins that are linked to neurodegeneration. Importantly, the PrP C C-terminal fragment C1 does not contain the reported binding sites for these oligomers. Western blotting would be a simple end point detection method for cell-based screening of compound libraries for effects on PrP C proteolysis or overall expression level. However, traditional Western blotting methods provide unreliable quantification and have only low throughput. Consequently, we explored capillary-based Western technology as a potential alternative; we believe that this study is the first to report analysis of PrP C using such an approach. We successfully optimized the detection and quantification of the deglycosylated forms of full-length PrP C and its C-terminal cleavage fragments C1 and C2, including simultaneous quantification of β-tubulin levels to control for loading error. We also developed and tested a method for performing all cell culture, lysis, and deglycosylation steps in 96-well microplates prior to capillary Western analysis. These advances represent steps along the way to the development of an automated, high-throughput screening pipeline to identify modulators of PrP C expression levels or proteolysis., (© 2019 Castle et al.)

Diabetic retinopathy (DR), a major complication of diabetes caused by vascular damage and pathological proliferation of retinal vessels, often progresses to vision loss. Vascular endothelial growth factor (VEGF) signaling plays a pivotal role in the development of DR, but the exact underlying molecular mechanisms remain ill-defined. Cellular prion protein (PrP c ) is a surface protein expressed by vascular endothelial cells, and the increased expression of PrP c is associated with physiological and pathological vascularization. Nevertheless, a role for PrP c in the development of DR has not been appreciated. Here, we addressed this question. We found that the development of streptozocin (STZ)-induced DR, but not the STZ-induced hyperglycemia/diabetes itself, was significantly attenuated in PrP c -KO mice, compared to control wildtype (WT) mice, evident by measurement of retinal vascular leakage, retinal neovascularization, a retinopathy score and visual acuity assessment. Moreover, the attenuation of DR severity seemingly resulted from attenuation of retinal neovascularization via VEGF/ras/rac signaling. Together, our study suggests a previously unappreciated role for PrP c in the development of DR.

To reveal the effects of PrP C on cells' biological processes and on gene expression. We established stable DF-1 (PrP C -knockdown (KD)) cells, and combined with DF-1 (wt) and DF-1 (PrP C -overexpression (OE)) cells that we previously established we studied the effects of chicken PrP C (PrP C ) on DF-1 cells' processes. Then by using high throughput sequencing technology (HTS) and bioinformatics, we analyzed the differentially expressed genes (DEGs) between these cells. The results show that compared with DF-1 (wt) and DF-1 (PrP C -scramble), DF-1 (PrP C -KD) are significantly decreased in adhesion, proliferation, formation rate of colony and cells number of colony, scratch wound healing rate, cells number of invasion and migration, S phase cell populations, but the apoptosis rate and G1 phase cell populations are significantly increased. Conversely, all of these features in DF-1 (PrP C -OE) are opposite. In addition, compared with DF-1 (wt), we found that there are totally 1055 DE genes between DF-1 (PrP C -KD) and DF-1 (PrP C -OE) cells. After Go and pathway enrichment analysis, we know that these DEGs are significantly enriched in cell, cell part, cellular process, and metabolic pathway. In short, we found that PrP C can promote DF-1 cells' processes except apoptosis. Furthermore, PrP C involves in the focal adhesion, cancer, ribosome, metabolic pathways, and so forth, and the overexpression of PrP C can promote the pathway of amoebiasis, but its down-regulation can promote the pathway of serotonergic synapse. However, the details are keeping unknown and that would be our next research., (© 2018 Wiley Periodicals, Inc.)

Normally folded prion protein (PrP C ) and its functions in healthy brains remain underappreciated compared with the intense study of its misfolded forms ("prions," PrP Sc ) during the pathobiology of prion diseases. This impedes the development of therapeutic strategies in Alzheimer's and prion diseases. Disrupting the zebrafish homologs of PrP C has provided novel insights; however, mutagenesis of the zebrafish paralog prp2 did not recapitulate previous dramatic developmental phenotypes, suggesting redundancy with the prp1 paralog. Here, we generated zebrafish prp1 loss-of-function mutant alleles and dual prp1 -/- ;prp2 -/- mutants. Zebrafish prp1 -/- and dual prp1 -/- ;prp2 -/- mutants resemble mammalian Prnp knockouts insofar as they lack overt phenotypes, which surprisingly contrasts with reports of severe developmental phenotypes when either prp1 or prp2 is knocked down acutely. Previous studies suggest that PrP C participates in neural cell development/adhesion, including in zebrafish where loss of prp2 affects adhesion and deposition patterns of lateral line neuromasts. In contrast with the expectation that prp1 's functions would be redundant to prp2 , they appear to have opposing functions in lateral line neurodevelopment. Similarly, loss of prp1 blunted the seizure susceptibility phenotypes observed in prp2 mutants, contrasting the expected exacerbation of phenotypes if these prion gene paralogs were serving redundant roles. In summary, prion mutant fish lack the overt phenotypes previously predicted, and instead they have subtle phenotypes similar to mammals. No evidence was found for functional redundancy in the zebrafish prion gene paralogs, and the phenotypes observed when each gene is disrupted individually are consistent with ancient functions of prion proteins in neurodevelopment and modulation of neural activity., (© 2018 by The American Society for Biochemistry and Molecular Biology, Inc.)

Prion diseases are phenotypically diverse, transmissible, neurodegenerative disorders affecting both animals and humans. Misfolding of the normal prion protein (PrP C ) into disease-associated conformers (PrP Sc ) is considered the critical etiological event underpinning prion diseases, with such misfolded isoforms linked to both disease transmission and neurotoxicity. Although important advances in our understanding of prion biology and pathogenesis have occurred over the last 3-4 decades, many fundamental questions remain to be resolved, including consensus regarding the principal pathways subserving neuronal dysfunction, as well as detailed biophysical characterization of PrP Sc species transmitting disease and/or directly associated with neurotoxicity. In vivo and in vitro models have been, and remain, critical to furthering our understanding across many aspects of prion disease patho-biology. Prion animal models are arguably the most authentic in vivo models of neurodegeneration that exist and have provided valuable and multifarious insights into pathogenesis; however, they are expensive and time-consuming, and it can be problematic to clearly discern evidence of direct PrP Sc neurotoxicity in the overall context of pathogenesis. In vitro models, in contrast, generally offer greater tractability and appear more suited to assessments of direct acute neurotoxicity but have until recently been relatively simplistic, and overall there remains a relative paucity of validated, biologically relevant models with heightened reliability as far as translational insights, contributing to difficulties in redressing our knowledge gaps in prion disease pathogenesis. In this review, we provide an overview of the spectrum and methodological diversity of in vivo and in vitro models of prion acute toxicity, as well as the pathogenic insights gained from these studies.

Calcium (Ca 2+ ) is an intracellular second messenger that ubiquitously masters remarkably diverse biological processes, including cell death. Growing evidence substantiates an involvement of the prion protein (PrP C ) in regulating neuronal Ca 2+ homeostasis, which could rationalize most of the wide range of functions ascribed to the protein. We have recently demonstrated that PrP C controls extracellular Ca 2+ fluxes, and mitochondrial Ca 2+ uptake, in neurons stimulated with glutamate (De Mario et al., J Cell Sci 2017; 130:2736-46), suggesting that PrP C protects neurons from threatening Ca 2+ overloads and excitotoxicity. In light of these results and of recent reports in the literature, here we review the connection of PrP C with Ca 2+ metabolism and also provide some speculative hints on the physiologic outcomes of this link. In addition, because PrP C is implicated in neurodegenerative diseases, including prion disorders and Alzheimer's disease, we will also discuss possible ways by which disruption of PrP C -Ca 2+ association could be mechanistically connected with these pathologies.

Abnormal structural changes of the prion protein (PrP) are the cause of prion disease in a wide range of mammals. However, spontaneous infected cases have not been reported in chicken. Genetic variations of the prion protein gene (PRNP) may impact susceptibility to prion disease but have not been investigated thus far. Because an investigation of the chicken PRNP can improve the understanding of characteristics related to resistance to prion disease, research on the chicken PRNP is highly desirable. In this study, we investigated the genetic characteristics of the chicken PRNP gene. For this, we performed direct sequencing in 106 Dekalb White chickens and analyzed the genotype and allele frequencies of chicken PRNP gene. We found two insertion and deletion polymorphisms in the chicken PRNP: c.163&#95;180delAACCCAGGGTACCCCCAT and c.268&#95;269insC. The former is a U2 hexapeptide deletion polymorphism. Of the 106 samples, 13 (12.26%) were insertion homozygotes, 89 (83.96%) were heterozygotes, and 4 (3.77%) were deletion homozygotes in c.163&#95;180delAACCCAGGGTACCCCCAT. In the c.268&#95;269insC polymorphism, 102 (96.23%) were deletion homozygotes, and 4 (3.77%) were heterozygotes. Insertion homozygotes of c.268&#95;269insC were not detected. Two polymorphisms were in perfect linkage disequilibrium (LD) with a D' value of 1.0, and three haplotypes were identified. Furthermore, PROVEAN evaluates 163&#95;180delAACCCAGGGTACCCCCAT as 'deleterious' with a score of - 13.173. Furthermore, single nucleotide polymorphisms (SNPs) in the open reading frame (ORF) of the PRNP gene were not found in the chicken. To the best of our knowledge, this was the first report on the genetic variations of the chicken PRNP gene.

Long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above USEPA standards is associated with Alzheimer's disease (AD) risk. Metropolitan Mexico City (MMC) children exhibit subcortical pretangles in infancy and cortical tau pre-tangles, NFTs, and amyloid phases 1-2 by the 2nd decade. Given their AD continuum, we measured in 507 normal cerebrospinal fluid (CSF) samples (MMC 354, controls 153, 12.82±6.73 y), a high affinity monoclonal non-phosphorylated tau antibody (non-P-Tau), as a potential biomarker of AD and axonal damage. In 81 samples, we also measured total tau (T-Tau), tau phosphorylated at threonine 181 (P-Tau), amyloid-β1-42, BDNF, and vitamin D. We documented by electron microscopy myelinated axonal size and the pathology associated with combustion-derived nanoparticles (CDNPs) in anterior cingulate cortex white matter in 6 young residents (16.25±3.34 y). Non-P-Tau showed a strong increase with age significantly faster among MMC versus controls (p = 0.0055). Aβ1 - 42 and BDNF concentrations were lower in MMC children (p = 0.002 and 0.03, respectively). Anterior cingulate cortex showed a significant decrease (p = <0.0001) in the average axonal size and CDNPs were associated with organelle pathology. Significant age increases in non-P-Tau support tau changes early in a population with axonal pathology and evolving AD hallmarks in the first two decades of life. Non-P-Tau is an early biomarker of axonal damage and potentially valuable to monitor progressive longitudinal changes along with AD multianalyte classical CSF markers. Neuroprotection of young urbanites with PM2.5 and CDNPs exposures ought to be a public health priority to halt the development of AD in the first two decades of life.

The term 'prion-like' is used to define some misfolded protein species that propagate intercellularly, triggering protein aggregation in recipient cells. For cell binding, both direct plasma membrane interaction and membrane receptors have been described for particular amyloids. In this respect, emerging evidence demonstrates that several β-sheet enriched proteins can bind to the cellular prion protein (PrP C ). Among other interactions, the physiological relevance of the binding between β-amyloid and PrP C has been a relevant focus of numerous studies. At the molecular level, published data point to the second charged cluster domain of the PrP C molecule as the relevant binding domain of the β-amyloid/PrP C interaction. In addition to β-amyloid, participation of PrP C in binding α-synuclein, responsible for neurodegenerative synucleopathies, has been reported. Although results indicate relevant participation of PrP C in the spreading of α-synuclein in living mice, the physiological relevance of the interaction remains elusive. In this comment, we focus our attention on summarizing current knowledge of PrP C as a receptor for amyloid proteins and its physiological significance, with particular focus on α-synuclein.

Cellular prion protein (PrP C ), the infective agent of transmissible spongiform encephalopathies, is thought to be related to several cellular physiological and physiopathological processes. We have previously reported that PrP C participates in multi-drug-resistance of gastric cancer. As the salient ligand molecule of PrP for participating in internalization and propagation of the scrapie form of prion protein (PrP Sc ), 37 kDa laminin receptor precursor protein (37LRP) shared the same gene coding sequence of MGr1-Ag, another protein previously found to be involved in multi-drug-resistance of gastric cancer in our lab. In the present study, we explored whether MGr1-Ag/37LRP contributed to PrP C mediated multi-drug-resistance in gastric cancer. Immunohistochemical staining showed similar expression patterns of MGr1-Ag/37LRP and PrP C in gastric cancer tissue serial sections. Western blot and immunohistochemistry also demonstrated correlative expression of MGr1-Ag/37LRP and PrP C in gastric cancer cell lines. Interaction between MGr1-Ag/37LRP and PrP C in gastric cancer cell lines and gastric cancer tissues were verified by immunofluorescence and co-immunoprecipitation. Furthermore, knockdown of MGr1-Ag/37LRP significantly attenuated PrP C induced multi-drug-resistance by sensitizing drug-induced apoptosis through inhibition of AKT activation. In conclusion, MGr1-Ag/37LRP may interact with PrP C and promote the PrP C induced multi-drug-resistance in gastric cancer through PI3K/AKT pathway. The current study elucidates the mechanism of how PrP C triggers intracellular signaling cascade resulting in multi-drug-resistance phenotype and provides a novel candidate molecular target against gastric cancer., Competing Interests: CONFLICTS OF INTEREST None.

An important goal of synthetic biology is to create novel proteins that provide life-sustaining functions in living organisms. Recent attempts to produce novel proteins have focused largely on rational design involving significant computational efforts. In contrast, nature does not design sequences a priori. Instead, nature relies on Darwinian evolution to select biologically functional sequences from nondesigned sequence space. To mimic natural selection in the laboratory, we combed through libraries of novel sequences and selected proteins that rescue E. coli cells deleted for conditionally essential genes. One such gene, gltA, encodes citrate synthase, the enzyme responsible for metabolic entry into the citric acid cycle. The de novo protein SynGltA was isolated as a rescuer of ΔgltA. However, SynGltA is not an enzyme. Instead, SynGltA allows cells to recover from a defect in central carbon and energy metabolism by altering the regulation of an alternative metabolic pathway. Specifically, SynGltA dramatically enhances the expression of prpC, a gene encoding methylcitrate synthase in the propionate degradation pathway. This endogenous protein has promiscuous catalytic activity, which when overexpressed, compensates for the deletion of citrate synthase. While the molecular details responsible for this overexpression have not been elucidated, the results clearly demonstrate that non-natural proteins-unrelated to sequences in nature-can provide life-sustaining functions by altering gene regulation in natural organisms.

The prion protein, PrP C , is a small, cell-surface glycoprotein notable primarily for its critical role in pathogenesis of the neurodegenerative disorders known as prion diseases. A hallmark of prion diseases is the conversion of PrP C into an abnormally folded isoform, which provides a template for further pathogenic conversion of PrP C , allowing disease to spread from cell to cell and, in some circumstances, to transfer to a new host. In addition to the putative neurotoxicity caused by the misfolded form(s), loss of normal PrP C function could be an integral part of the neurodegenerative processes and, consequently, significant research efforts have been directed toward determining the physiological functions of PrP C . In this review, we first summarise important aspects of the biochemistry of PrP C before moving on to address the current understanding of the various proposed functions of the protein, including details of the underlying molecular mechanisms potentially involved in these functions. Over years of study, PrP C has been associated with a wide array of different cellular processes and many interacting partners have been suggested. However, recent studies have cast doubt on the previously well-established links between PrP C and processes such as stress-protection, copper homeostasis and neuronal excitability. Instead, the functions best-supported by the current literature include regulation of myelin maintenance and of processes linked to cellular differentiation, including proliferation, adhesion, and control of cell morphology. Intriguing connections have also been made between PrP C and the modulation of circadian rhythm, glucose homeostasis, immune function and cellular iron uptake, all of which warrant further investigation.

Background: Clustered regularly interspaced short palindromic repeats interference (CRISPRi) has provided an efficient approach for targeted gene inhibition. A non-model microorganism Halomonas species TD01 has been developed as a promising industrial producer of polyhydroxyalkanoates (PHA), a family of biodegradable polyesters accumulated by bacteria as a carbon and energy reserve compound. A controllable gene repression system, such as CRISPRi, is needed for Halomonas sp. TD01 to regulate its gene expression levels., Results: For the first time CRISPRi was successfully used in Halomonas sp. TD01 to repress expression of ftsZ gene encoding bacterial fission ring formation protein, leading to an elongated cell morphology with typical filamentous shape similar to phenomenon observed with Escherichia coli. CRISPRi was employed to regulate expressions of prpC gene encoding 2-methylcitrate synthase for regulating 3-hydroxyvalerate monomer ratio in PHBV copolymers of 3-hydroxybutyrate (HB) and 3-hydroxyvalerate (HV). Percentages of HV in PHBV copolymers were controllable ranging from less than 1 to 13%. Furthermore, repressions on gltA gene encoding citrate synthase channeled more acetyl-CoA from the tricarboxylic acid (TCA) cycle to poly(3-hydroxybutyrate) (PHB) synthesis. The PHB accumulation by Halomonas sp. TD01 with its gltA gene repressed in various intensities via CRISPRi was increased by approximately 8% compared with the wild type control containing the CRISPRi vector without target., Conclusions: It has now been confirmed that the CRISPRi system can be applied to Halomonas sp. TD01, a promising industrial strain for production of various PHA and chemicals under open and continuous fermentation process conditions. In details, the CRISPRi system was successfully designed in this study to target genes of ftsZ, prpC and gltA, achieving longer cell sizes, channeling more substrates to PHBV and PHB synthesis, respectively. CRISPRi can be expected to use for more metabolic engineering applications in non-model organisms.

Biological effect of poly-L-arginine (PLR), the linear homopolymer comprised of L-arginine, was investigated to determine the activity of suppressing prions. PLR decreased the level of scrapie prion protein (PrP Sc ) in cultured cells permanently infected with prions in a concentration-dependent manner. The PrP Sc inhibition efficacy of PLR was greater than that of another prion-suppressant poly-L-lysine (PLK) in a molecular mass-dependent fashion. The effective concentration of PLR to inhibit prions was achieved safely below the cytotoxic concentrations, and overall cytotoxicity of PLR was similar to that of PLK. PLR did not alter the cellular prion protein (PrP C ) level and was unable to change the states of preformed recombinant PrP aggregates and PrP Sc from prion-infected cells. These data eliminate the possibility that the action mechanism of PLR is through removal of PrP C and pre-existing PrP Sc . However, PLR formed complexes with plasminogen that stimulates prion propagation via conversion of PrP C to the misfolded isoform, PrP Sc . The plasminogen-PLR complex demonstrated the greater positive surface charge values than the similar complex with PLK, raising the possibility that PLR interferes with the role of cofactor for PrP Sc generation better than PLK.

Prion diseases are a group of invariably fatal and transmissible neurodegenerative disorders that are associated with the misfolding of the normal cellular prion protein, with the misfolded conformers constituting an infectious unit referred to as a "prion". Prions can spread within an affected organism by directly propagating this misfolding within and between cells and can transmit disease between animals of the same and different species. Prion diseases have a range of clinical phenotypes in humans and animals, with a principle determinant of this attributed to different conformations of the misfolded protein, referred to as prion strains. This chapter will describe the different clinical manifestations of prion diseases, the evidence that these diseases can be transmitted by an infectious protein and how the misfolding of this protein causes disease.

Like numerous proteins of various structural and functional classes, the glycosylphosphatidylinositol (GPI)-anchored cellular prion protein (PrP C ) has been recognized to undergo endoproteolytic processing for decades, a phenomenon observed in various cultured cell lines, as well as human and several animal tissue extracts. Despite this, the physiological significance of PrP C proteolytic cleavage has not yet been entirely elucidated. Experimental evidence suggests independent normal biological functions of the full-length and truncated PrP C species, as well as probable links of endoproteolysis to prion disease transmission susceptibility, pathogenesis, and toxicity. The accurate characterization of constitutive PrP C processing, through the method outlined in this chapter, is therefore an important tool in order to investigate the biological relevance of the alternative cleavage events.

Extracellular vesicles (EVs) are composed of microvesicles and exosomes. Exosomes are small membrane vesicles (40-120 nm sized) of endosomal origin released in the extracellular medium from cells when multivesicular bodies fuse with the plasma membrane, whereas microvesicles (i.e., shedding vesicles, 100 nm to 1 μm sized) bud from the plasma membrane. Exosomes and microvesicles carry functional proteins and nucleic acids (especially mRNAs and microRNAs) that can be transferred to surrounding cells and tissues and can impact multiple dimensions of the cellular life. Most of the cells, if not all, from neuronal to immune cells, release exosomes and microvesicles in the extracellular medium, and all biological fluids including blood (serum/plasma), urine, cerebrospinal fluid, and saliva contain EVs.Prion-infected cultured cells are known to secrete infectivity into their environment. We characterized this cell-free form of prions and showed that infectivity was associated with exosomes. Since exosomes are produced by a variety of cells, including cells that actively accumulate prions, they could be a vehicle for infectivity in body fluids and could participate to the dissemination of prions in the organism. In addition, such infectious exosomes also represent a natural, simple, biological material to get key information on the abnormal PrP forms associated with infectivity.In this chapter, we describe first a method that allows exosomes and microvesicles isolation from prion-infected cell cultures and in a second time the strategies to characterize the prions containing exosomes and their ability to disseminate the prion agent.

More than thirty years have passed since the discovery of the prion protein (PrP) and its causative role in transmissible spongiform encephalopathy. Since a combination of both gain- and loss-of-function mechanisms may underlay prion pathogenesis, understanding the physiological role of PrP may give important clues about disease mechanisms. Historically, the primary strategy for prion research has involved the use of human tissue, cell cultures and mammalian animal models. Nevertheless, experimental difficulties of in vivo studies and controversial observations obtained in these systems have stimulated the search for alternative animal models. PrPC is highly conserved in mammals, and PrPC-related orthologs are expressed in zebrafish, a vertebrate model organism suitable to study the mechanisms associated with human diseases. Invertebrate models, as they do not express PrPC have served to investigate the neurotoxic mechanisms of mammalian PrP. Here we overview most recent advances in the study of PrP function in normal and pathogenic conditions based on non-mammalian studies, highlighting the contribution of zebrafish, fly and worms to our current understanding of PrP biology., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)