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Adhikari UK, Sakiz E, Habiba U, Mikhael M, Senesi M, David MA, Guillemin GJ, Ooi L, Karl T, Collins S, Tayebi M. Treatment of microglia with Anti-PrP monoclonal antibodies induces neuronal apoptosis in vitro. Heliyon 2021; 7:e08644. [PMID: 35005289 PMCID: PMC8715334 DOI: 10.1016/j.heliyon.2021.e08644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/23/2021] [Accepted: 12/16/2021] [Indexed: 11/04/2022] Open
Abstract
Previous reports highlighted the neurotoxic effects caused by some motif-specific anti-PrPC antibodies in vivo and in vitro. In the current study, we investigated the detailed alterations of the proteome with liquid chromatography–mass spectrometry following direct application of anti-PrPC antibodies on mouse neuroblastoma cells (N2a) and mouse primary neuronal (MPN) cells or by cross-linking microglial PrPC with anti-PrPC antibodies prior to co-culture with the N2a/MPN cells. Here, we identified 4 (3 upregulated and 1 downregulated) and 17 (11 upregulated and 6 downregulated) neuronal apoptosis-related proteins following treatment of the N2a and N11 cell lines respectively when compared with untreated cells. In contrast, we identified 1 (upregulated) and 4 (2 upregulated and 2 downregulated) neuronal apoptosis-related proteins following treatment of MPN cells and N11 when compared with untreated cells. Furthermore, we also identified 3 (2 upregulated and 1 downregulated) and 2 (1 upregulated and 1 downregulated) neuronal apoptosis-related related proteins following treatment of MPN cells and N11 when compared to treatment with an anti-PrP antibody that lacks binding specificity for mouse PrP. The apoptotic effect of the anti-PrP antibodies was confirmed with flow cytometry following labelling of Annexin V-FITC. The toxic effects of the anti-PrP antibodies was more intense when antibody-treated N11 were co-cultured with the N2a and the identified apoptosis proteome was shown to be part of the PrPC-interactome. Our observations provide a new insight into the prominent role played by microglia in causing neurotoxic effects following treatment with anti-PrPC antibodies and might be relevant to explain the antibody mediated toxicity observed in other related neurodegenerative diseases such as Alzheimer. Antibody cross-linking neuronal PrPC induces apoptosis. Antibody cross-linking microglial PrPC induces neuronal apoptosis. Different apoptotic pathways were triggered by specific anti-PrP antibody treatments.
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Adhikari UK, Sakiz E, Zhou X, Habiba U, Kumar S, Mikhael M, Senesi M, Guang Li C, Guillemin GJ, Ooi L, David MA, Collins S, Karl T, Tayebi M. Cross-Linking Cellular Prion Protein Induces Neuronal Type 2-Like Hypersensitivity. Front Immunol 2021; 12:639008. [PMID: 34394070 PMCID: PMC8361482 DOI: 10.3389/fimmu.2021.639008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/13/2021] [Indexed: 01/13/2023] Open
Abstract
Background Previous reports identified proteins associated with ‘apoptosis’ following cross-linking PrPC with motif-specific anti-PrP antibodies in vivo and in vitro. The molecular mechanisms underlying this IgG-mediated neurotoxicity and the role of the activated proteins in the apoptotic pathways leading to neuronal death has not been properly defined. Previous reports implicated a number of proteins, including apolipoprotein E, cytoplasmic phospholipase A2, prostaglandin and calpain with anti-PrP antibody-mediated ‘apoptosis’, however, these proteins are also known to play an important role in allergy. In this study, we investigated whether cross-linking PrPC with anti-PrP antibodies stimulates a neuronal allergenic response. Methods Initially, we predicted the allergenicity of the epitope sequences associated with ‘neurotoxic’ anti-PrP antibodies using allergenicity prediction servers. We then investigated whether anti-PrP antibody treatment of mouse primary neurons (MPN), neuroblastoma cells (N2a) and microglia (N11) cell lines lead to a neuronal allergenic response. Results In-Silico studies showed that both tail- and globular-epitopes were allergenic. Specifically, binding regions that contain epitopes for previously reported ‘neurotoxic’ antibodies such as ICSM18 (146-159), ICSM35 (91-110), POM 1 (138-147) and POM 3 (95-100) lead to activation of allergenic related proteins. Following direct application of anti-PrPC antibodies on N2a cells, we identified 4 neuronal allergenic-related proteins when compared with untreated cells. Furthermore, we identified 8 neuronal allergenic-related proteins following treatment of N11 cells with anti-PrPC antibodies prior to co-culture with N2a cells when compared with untreated cells. Antibody treatment of MPN or MPN co-cultured with antibody-treated N11 led to identifying 10 and 7 allergenic-related proteins when compared with untreated cells. However, comparison with 3F4 antibody treatment revealed 5 and 4 allergenic-related proteins respectively. Of importance, we showed that the allergenic effects triggered by the anti-PrP antibodies were more potent when antibody-treated microglia were co-cultured with the neuroblastoma cell line. Finally, co-culture of N2a or MPN with N11-treated with anti-PrP antibodies resulted in significant accumulation of NO and IL6 but not TNF-α in the cell culture media supernatant. Conclusions This study showed for the first time that anti-PrP antibody binding to PrPC triggers a neuronal hypersensitivity response and highlights the important role of microglia in triggering an IgG-mediated neuronal hypersensitivity response. Moreover, this study provides an important impetus for including allergenic assessment of therapeutic antibodies for neurodegenerative disorders to derive safe and targeted biotherapeutics.
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Affiliation(s)
| | - Elif Sakiz
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Xian Zhou
- National Institute of Complementary Medicine (NICM) Health Research Institute, Western Sydney University, Campbelltown, NSW, Australia
| | - Umma Habiba
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Sachin Kumar
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Meena Mikhael
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Matteo Senesi
- Australian National Creutzfeldt-Jakob Disease Registry, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Chun Guang Li
- National Institute of Complementary Medicine (NICM) Health Research Institute, Western Sydney University, Campbelltown, NSW, Australia
| | - Gilles J Guillemin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Wollongong, NSW, Australia
| | - Lezanne Ooi
- School of Chemistry and Molecular Bioscience, Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | | | - Steven Collins
- Australian National Creutzfeldt-Jakob Disease Registry, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Tim Karl
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia.,Neuroscience Research Australia (NeuRA), Sydney, NSW, Australia.,School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Mourad Tayebi
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
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Trovato A, Panelli S, Strozzi F, Cambulli C, Barbieri I, Martinelli N, Lombardi G, Capoferri R, Williams JL. Expression of genes involved in the T cell signalling pathway in circulating immune cells of cattle 24 months following oral challenge with Bovine Amyloidotic Spongiform Encephalopathy (BASE). BMC Vet Res 2015; 11:105. [PMID: 25956229 PMCID: PMC4424883 DOI: 10.1186/s12917-015-0412-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 04/16/2015] [Indexed: 11/19/2022] Open
Abstract
Background Bovine Amyloidotic Spongiform Encephalopathy (BASE) is a variant of classical BSE that affects cows and can be transmitted to primates and mice. BASE is biochemically different from BSE and shares some molecular and histo-pathological features with the MV2 sub-type of human sporadic Creutzfeld Jakob Disease (sCJD). Results The present work examined the effects of BASE on gene expression in circulating immune cells. Ontology analysis of genes differentially expressed between cattle orally challenged with brain homogenate from cattle following intracranial inoculation with BASE and control cattle identified three main pathways which were affected. Within the immune function pathway, the most affected genes were related to the T cell receptor-mediated T cell activation pathways. The differential expression of these genes in BASE challenged animals at 10,12 and 24 months following challenge, vs unchallenged controls, was investigated by real time PCR. Conclusions The results of this study show that the effects of prion diseases are not limited to the CNS, but involve the immune system and particularly T cell signalling during the early stage following challenge, before the appearance of clinical signs.
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Affiliation(s)
- Andrea Trovato
- Parco Tecnologico Padano, via Einstein, Lodi, 26900, Italy.
| | - Simona Panelli
- Istituto Sperimentale Italiano Lazzaro Spallanzani, Loc. La Quercia, 26027, Rivolta d'Adda, Italy.
| | | | - Caterina Cambulli
- Istituto Sperimentale Italiano Lazzaro Spallanzani, Loc. La Quercia, 26027, Rivolta d'Adda, Italy.
| | - Ilaria Barbieri
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via Bianchi 9, 25124, Brescia, Italy.
| | - Nicola Martinelli
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via Bianchi 9, 25124, Brescia, Italy.
| | - Guerino Lombardi
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, via Bianchi 9, 25124, Brescia, Italy.
| | - Rossana Capoferri
- Istituto Sperimentale Italiano Lazzaro Spallanzani, Loc. La Quercia, 26027, Rivolta d'Adda, Italy.
| | - John L Williams
- Parco Tecnologico Padano, via Einstein, Lodi, 26900, Italy. .,Present address: School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, SA, 5371, Australia.
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Didonna A. Prion protein and its role in signal transduction. Cell Mol Biol Lett 2013; 18:209-30. [PMID: 23479001 PMCID: PMC6275729 DOI: 10.2478/s11658-013-0085-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/18/2013] [Indexed: 11/20/2022] Open
Abstract
Prion diseases are a class of fatal neurodegenerative disorders that can be sporadic, genetic or iatrogenic. They are characterized by the unique nature of their etiologic agent: prions (PrP(Sc)). A prion is an infectious protein with the ability to convert the host-encoded cellular prion protein (PrP(C)) into new prion molecules by acting as a template. Since Stanley B. Prusiner proposed the "protein-only" hypothesis for the first time, considerable effort has been put into defining the role played by PrP(C) in neurons. However, its physiological function remains unclear. This review summarizes the major findings that support the involvement of PrP(C) in signal transduction.
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Affiliation(s)
- Alessandro Didonna
- Davee Department of Neurology, Feinberg School of Medicine Northwestern University, Chicago, IL 60611, USA.
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Tayebi M, David M, Bate C, Jones D, Taylor W, Morton R, Pollard J, Hawke S. Epitope-specific anti-prion antibodies upregulate apolipoprotein E and disrupt membrane cholesterol homeostasis. J Gen Virol 2010; 91:3105-15. [DOI: 10.1099/vir.0.023838-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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A camelid anti-PrP antibody abrogates PrP replication in prion-permissive neuroblastoma cell lines. PLoS One 2010; 5:e9804. [PMID: 20339552 PMCID: PMC2842437 DOI: 10.1371/journal.pone.0009804] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 02/26/2010] [Indexed: 11/19/2022] Open
Abstract
The development of antibodies effective in crossing the blood brain barrier (BBB), capable of accessing the cytosol of affected cells and with higher affinity for PrPSc would be of paramount importance in arresting disease progression in its late stage and treating individuals with prion diseases. Antibody-based therapy appears to be the most promising approach following the exciting report from White and colleagues, establishing the “proof-of-principle” for prion-immunotherapy. After passive transfer, anti-prion antibodies were shown to be very effective in curing peripheral but not central rodent prion disease, due to the fact that these anti-prion antibodies are relatively large molecules and cannot therefore cross the BBB. Here, we show that an anti-prion antibody derived from camel immunised with murine scrapie material adsorbed to immunomagnetic beads is able to prevent infection of susceptible N2a cells and cure chronically scrapie-infected neuroblastoma cultures. This antibody was also shown to transmigrate across the BBB and cross the plasma membrane of neurons to target cytosolic PrPC. In contrast, treatment with a conventional anti-prion antibody derived from mouse immunised with recombinant PrP protein was unable to prevent recurrence of PrPSc replication. Furthermore, our camelid antibody did not display any neurotoxic effects following treatment of susceptible N2a cells as evidenced by TUNEL staining. These findings demonstrate the potential use of anti-prion camelid antibodies for the treatment of prion and other related diseases via non-invasive means.
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A genome-wide association study on African-ancestry populations for asthma. J Allergy Clin Immunol 2009; 125:336-346.e4. [PMID: 19910028 DOI: 10.1016/j.jaci.2009.08.031] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 08/06/2009] [Accepted: 08/21/2009] [Indexed: 12/18/2022]
Abstract
BACKGROUND Asthma is a complex disease characterized by striking ethnic disparities not explained entirely by environmental, social, cultural, or economic factors. Of the limited genetic studies performed on populations of African descent, notable differences in susceptibility allele frequencies have been observed. OBJECTIVES We sought to test the hypothesis that some genes might contribute to the profound disparities in asthma. METHODS We performed a genome-wide association study in 2 independent populations of African ancestry (935 African American asthmatic cases and control subjects from the Baltimore-Washington, DC, area and 929 African Caribbean asthmatic subjects and their family members from Barbados) to identify single-nucleotide polymorphisms (SNPs) associated with asthma. RESULTS A meta-analysis combining these 2 African-ancestry populations yielded 3 SNPs with a combined P value of less than 10(-5) in genes of potential biologic relevance to asthma and allergic disease: rs10515807, mapping to the alpha-1B-adrenergic receptor (ADRA1B) gene on chromosome 5q33 (3.57 x 10(-6)); rs6052761, mapping to the prion-related protein (PRNP) gene on chromosome 20pter-p12 (2.27 x 10(-6)); and rs1435879, mapping to the dipeptidyl peptidase 10 (DPP10) gene on chromosome 2q12.3-q14.2. The generalizability of these findings was tested in family and case-control panels of United Kingdom and German origin, respectively, but none of the associations observed in the African groups were replicated in these European studies. Evidence for association was also examined in 4 additional case-control studies of African Americans; however, none of the SNPs implicated in the discovery population were replicated. CONCLUSIONS This study illustrates the complexity of identifying true associations for a complex and heterogeneous disease, such as asthma, in admixed populations, especially populations of African descent.
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Jiayu W, Zhu H, Ming X, Xiong W, Songbo W, Bocui S, Wensen L, Jiping L, Keying M, Zhongyi L, Hongwei G. Mapping the interaction site of prion protein and Sho. Mol Biol Rep 2009; 37:2295-300. [PMID: 19685161 DOI: 10.1007/s11033-009-9722-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 08/04/2009] [Indexed: 11/24/2022]
Abstract
The cellular prion protein (PrP(C)) is a highly conserved protein among mammals and is considered to have important cellular functions. Despite decades of intensive research, however, the physiological function of PrP(C) remains unclear. Sho (Shadoo, shadow of prion protein) and PrP(C) have similar N-terminals, which suggests that the two proteins share biological functions. Using truncation mutants of both proteins and yeast two-hybrid analysis, with validation by co-immunoprecipitation and surface plasmon resonance (SPR), we have identified an interaction between Sho 61-77 and PrP(C) 108-126 domains. This indicates that Sho may play a role in the physiological function of PrP(C) and prion pathogenesis.
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Affiliation(s)
- Wan Jiayu
- Institute of Military Veterinary, Academy of Military Medical Sciences, 1068 Qinglong Road, Changchun, 130062 China
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Ingram RJ, Isaacs JD, Kaur G, Lowther DE, Reynolds CJ, Boyton RJ, Collinge J, Jackson GS, Altmann DM. A role of cellular prion protein in programming T‐cell cytokine responses in disease. FASEB J 2009; 23:1672-84. [DOI: 10.1096/fj.08-116087] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Rebecca J. Ingram
- Human Disease Immunogenetics GroupDepartment of Infectious Diseases and ImmunityHammersmith HospitalImperial College LondonLondonUK
| | - Jeremy D. Isaacs
- Human Disease Immunogenetics GroupDepartment of Infectious Diseases and ImmunityHammersmith HospitalImperial College LondonLondonUK
- MRC Prion UnitDepartment of Neurodegenerative DiseaseInstitute of NeurologyUniversity College LondonQueen SquareLondonUK
| | - Gurman Kaur
- Human Disease Immunogenetics GroupDepartment of Infectious Diseases and ImmunityHammersmith HospitalImperial College LondonLondonUK
| | - Daniel E. Lowther
- Human Disease Immunogenetics GroupDepartment of Infectious Diseases and ImmunityHammersmith HospitalImperial College LondonLondonUK
| | - Catherine J. Reynolds
- Lung Immunology GroupImmunology and InfectionNHLISir Alexander Fleming Building, South Kensington CampusLondonUK
| | - Rosemary J. Boyton
- Lung Immunology GroupImmunology and InfectionNHLISir Alexander Fleming Building, South Kensington CampusLondonUK
| | - John Collinge
- MRC Prion UnitDepartment of Neurodegenerative DiseaseInstitute of NeurologyUniversity College LondonQueen SquareLondonUK
| | - Graham S. Jackson
- MRC Prion UnitDepartment of Neurodegenerative DiseaseInstitute of NeurologyUniversity College LondonQueen SquareLondonUK
| | - Daniel M. Altmann
- Human Disease Immunogenetics GroupDepartment of Infectious Diseases and ImmunityHammersmith HospitalImperial College LondonLondonUK
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Linden R, Martins VR, Prado MAM, Cammarota M, Izquierdo I, Brentani RR. Physiology of the prion protein. Physiol Rev 2008; 88:673-728. [PMID: 18391177 DOI: 10.1152/physrev.00007.2007] [Citation(s) in RCA: 435] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Prion diseases are transmissible spongiform encephalopathies (TSEs), attributed to conformational conversion of the cellular prion protein (PrP(C)) into an abnormal conformer that accumulates in the brain. Understanding the pathogenesis of TSEs requires the identification of functional properties of PrP(C). Here we examine the physiological functions of PrP(C) at the systemic, cellular, and molecular level. Current data show that both the expression and the engagement of PrP(C) with a variety of ligands modulate the following: 1) functions of the nervous and immune systems, including memory and inflammatory reactions; 2) cell proliferation, differentiation, and sensitivity to programmed cell death both in the nervous and immune systems, as well as in various cell lines; 3) the activity of numerous signal transduction pathways, including cAMP/protein kinase A, mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt pathways, as well as soluble non-receptor tyrosine kinases; and 4) trafficking of PrP(C) both laterally among distinct plasma membrane domains, and along endocytic pathways, on top of continuous, rapid recycling. A unified view of these functional properties indicates that the prion protein is a dynamic cell surface platform for the assembly of signaling modules, based on which selective interactions with many ligands and transmembrane signaling pathways translate into wide-range consequences upon both physiology and behavior.
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Affiliation(s)
- Rafael Linden
- Instituto de Biofísica da Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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11
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Isaacs JD, Garden OA, Kaur G, Collinge J, Jackson GS, Altmann DM. The cellular prion protein is preferentially expressed by CD4+ CD25+ Foxp3+ regulatory T cells. Immunology 2008; 125:313-9. [PMID: 18462346 DOI: 10.1111/j.1365-2567.2008.02853.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Post-translational modification of the cellular prion protein (PrP(C)) is intimately associated with the pathogenesis of prion disease, yet the normal function of the protein remains unclear. PrP(C) is expressed in lymphoid cells and is known to be a T-cell activation antigen. Further, transcription profiling studies of regulatory T cells have shown preferential overexpression of PrP(C), suggesting a possible role in regulatory function. We report that both the expression of PrP message and cell surface PrP(C) levels are increased in murine CD4(+) CD25(+) regulatory T cells compared with CD4(+) CD25(-) cells. However, PrP(0/0) mice do not show altered regulatory T-cell numbers or forkhead box P3 (Foxp3) expression levels, or impaired regulatory T-cell function in vitro. Nevertheless, the preferential expression of surface PrP(C) by regulatory T cells raises the possibility that therapeutic ligation of PrP(C) might alter immune regulation.
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Affiliation(s)
- Jeremy D Isaacs
- Department of Infectious Diseases and Immunity, Imperial College, Hammersmith Hospital, London, UK
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12
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Zomosa-Signoret V, Arnaud JD, Fontes P, Alvarez-Martinez MT, Liautard JP. Physiological role of the cellular prion protein. Vet Res 2007; 39:9. [PMID: 18073096 DOI: 10.1051/vetres:2007048] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 09/21/2007] [Indexed: 01/30/2023] Open
Abstract
The prion protein (PrP) plays a key role in the pathogenesis of prion diseases. However, the normal function of the protein remains unclear. The cellular isoform (PrP(C)) is expressed most abundantly in the brain, but has also been detected in other non-neuronal tissues as diverse as lymphoid cells, lung, heart, kidney, gastrointestinal tract, muscle, and mammary glands. Cell biological studies of PrP contribute to our understanding of PrP(C) function. Like other membrane proteins, PrP(C) is post-translationally processed in the endoplasmic reticulum and Golgi on its way to the cell surface after synthesis. Cell surface PrP(C) constitutively cycles between the plasma membrane and early endosomes via a clathrin-dependent mechanism, a pathway consistent with a suggested role for PrP(C) in cellular trafficking of copper ions. Although PrP(-/-) mice have been reported to have only minor alterations in immune function, PrP(C) is up-regulated in T cell activation and may be expressed at higher levels by specialized classes of lymphocytes. Furthermore, antibody cross-linking of surface PrP(C) modulates T cell activation and leads to rearrangements of lipid raft constituents and increased phosphorylation of signaling proteins. These findings appear to indicate an important but, as yet, ill-defined role in T cell function. Recent work has suggested that PrP(C) is required for self-renewal of haematopoietic stem cells. PrP(C) is highly expressed in the central nervous system, and since this is the major site of prion pathology, most interest has focused on defining the role of PrP(C) in neurones. Although PrP(-/-) mice have a grossly normal neurological phenotype, even when neuronal PrP(C) is knocked out postnatally, they do have subtle abnormalities in synaptic transmission, hippocampal morphology, circadian rhythms, and cognition and seizure threshold. Other postulated neuronal roles for PrP(C) include copper-binding, as an anti- and conversely, pro-apoptotic protein, as a signaling molecule, and in supporting neuronal morphology and adhesion. The prion protein may also function as a metal binding protein such as copper, yielding cellular antioxidant capacity suggesting a role in the oxidative stress homeostasis. Finally, recent observations on the role of PrP(C) in long-term memory open a challenging field.
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Abstract
Prion protein (PrP) plays a key role in the pathogenesis of prion diseases. However, the normal function of the protein remains unclear. The cellular isoform (PrP(C)) is expressed widely in the immune system, in haematopoietic stem cells and mature lymphoid and myeloid compartments in addition to cells of the central nervous system. It is up-regulated in T cell activation and may be expressed at higher levels by specialized classes of lymphocyte. Furthermore, antibody cross-linking of surface PrP modulates T cell activation and leads to rearrangements of lipid raft constituents and increased phosphorylation of signalling proteins. These findings appear to indicate an important but, as yet, ill-defined role in T cell function. Although PrP(-/-) mice have been reported to have only minor alterations in immune function, recent work has suggested that PrP is required for self-renewal of haematopoietic stem cells. Here, we consider the evidence for a distinctive role for PrP(C) in the immune system and what the effects of anti-prion therapeutics may be on immune function.
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Affiliation(s)
- J D Isaacs
- Human Disease Immunogenetics Group, Department of Infectious Diseases and Immunity, Imperial College London, Hammersmith Hospital, London, UK
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Vana K, Zuber C, Nikles D, Weiss S. Novel Aspects of Prions, Their Receptor Molecules, and Innovative Approaches for TSE Therapy. Cell Mol Neurobiol 2006; 27:107-28. [PMID: 17151946 DOI: 10.1007/s10571-006-9121-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 09/20/2006] [Indexed: 10/23/2022]
Abstract
1. Prion diseases are a group of rare, fatal neurodegenerative diseases, also known as transmissible spongiform encephalopathies (TSEs), that affect both animals and humans and include bovine spongiform encephalopathy (BSE) in cattle, scrapie in sheep, chronic wasting disease (CWD) in deer and elk, and Creutzfeldt-Jakob disease (CJD) in humans. TSEs are usually rapidly progressive and clinical symptoms comprise dementia and loss of movement coordination due to the accumulation of an abnormal isoform (PrP(Sc)) of the host-encoded prion protein (PrP(c)). 2. This article reviews the current knowledge on PrP(c) and PrP(Sc), prion replication mechanisms, interaction partners of prions, and their cell surface receptors. Several strategies, summarized in this article, have been investigated for an effective antiprion treatment including development of a vaccination therapy and screening for potent chemical compounds. Currently, no effective treatment for prion diseases is available. 3. The identification of the 37 kDa/67 kDa laminin receptor (LRP/LR) and heparan sulfate as cell surface receptors for prions, however, opens new avenues for the development of alternative TSE therapies.
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Affiliation(s)
- Karen Vana
- Laboratorium für Molekulare Biologie, Genzentrum, Institut für Biochemie der Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377, München, Germany
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