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Vilches S, Vergara C, Nicolás O, Mata Á, Del Río JA, Gavín R. Domain-Specific Activation of Death-Associated Intracellular Signalling Cascades by the Cellular Prion Protein in Neuroblastoma Cells. Mol Neurobiol 2015; 53:4438-48. [PMID: 26250617 DOI: 10.1007/s12035-015-9360-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/13/2015] [Indexed: 10/23/2022]
Abstract
The biological functions of the cellular prion protein remain poorly understood. In fact, numerous studies have aimed to determine specific functions for the different protein domains. Studies of cellular prion protein (PrP(C)) domains through in vivo expression of molecules carrying internal deletions in a mouse Prnp null background have provided helpful data on the implication of the protein in signalling cascades in affected neurons. Nevertheless, understanding of the mechanisms underlying the neurotoxicity induced by these PrP(C) deleted forms is far from complete. To better define the neurotoxic or neuroprotective potential of PrP(C) N-terminal domains, and to overcome the heterogeneity of results due to the lack of a standardized model, we used neuroblastoma cells to analyse the effects of overexpressing PrP(C) deleted forms. Results indicate that PrP(C) N-terminal deleted forms were properly processed through the secretory pathway. However, PrPΔF35 and PrPΔCD mutants led to death by different mechanisms sharing loss of alpha-cleavage and activation of caspase-3. Our data suggest that both gain-of-function and loss-of-function pathogenic mechanisms may be associated with N-terminal domains and may therefore contribute to neurotoxicity in prion disease. Dissecting the molecular response induced by PrPΔF35 may be the key to unravelling the physiological and pathological functions of the prion protein.
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Affiliation(s)
- Silvia Vilches
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Cristina Vergara
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Oriol Nicolás
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Ágata Mata
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - José A Del Río
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain. .,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain.
| | - Rosalina Gavín
- Molecular and Cellular Neurobiotechnology, Barcelona Science Park, Institute for Bioengineering of Catalonia (IBEC), Parc Científic de Catalunya, Baldiri Reixac 15-21, 08028, Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain. .,Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain.
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Dean SL, Wright CL, Hoffman JF, Wang M, Alger BE, McCarthy MM. Prostaglandin E2 stimulates estradiol synthesis in the cerebellum postnatally with associated effects on Purkinje neuron dendritic arbor and electrophysiological properties. Endocrinology 2012; 153:5415-27. [PMID: 23054057 PMCID: PMC3473195 DOI: 10.1210/en.2012-1350] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Prostaglandins (PGs) are ubiquitous membrane-derived, lipid-signaling molecules with wide ranging effects throughout the body. In the brain, PGE(2) is the key regulator of fever after inflammation but is also implicated in neural development and synaptic plasticity. The steroid hormone estradiol is also a key regulator of neural development and synaptic plasticity. Recently, we showed that administering cyclooxygenase (COX) inhibitors to block PGE(2) production increased the total length of Purkinje cell dendrites, the number of dendritic spines, and the level of spinophilin protein, which is enriched in dendritic spines. Correspondingly, PGE(2) administration into the cerebellum decreased spinophilin protein content. We now report that PGE(2) stimulates estradiol synthesis in the immature rat cerebellum via enhanced activity of the aromatase enzyme. Treatment with cyclooxygenase inhibitors reduced cerebellar aromatase activity and estradiol content whereas PGE(2) administration increased both. Treatment with either PGE(2) or estradiol stunted Purkinje neuron dendritic length and complexity and produced a corresponding reduction in spinophilin content. Treatment with formestane to inhibit aromatase activity led to excessive sprouting of the dendritic tree, whereas elevated estradiol had the opposite effect. Electrophysiological measurements from Purkinje neurons revealed novel sex differences in input resistance and membrane capacitance that were abolished by estradiol exposure, whereas a sex difference in the amplitude of the afterhyperpolarization after an action potential was not. Correlated changes in action potential threshold suggest that prolonged alterations in neuronal firing activity could be a consequence of increased estradiol content during the second week of life. These findings reveal a previously unappreciated role for PG-stimulated steroidogenesis in the developing brain and a new potential route for inflammation-mediated disruption of neuronal maturation.
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Dean SL, Knutson JF, Krebs-Kraft DL, McCarthy MM. Prostaglandin E2 is an endogenous modulator of cerebellar development and complex behavior during a sensitive postnatal period. Eur J Neurosci 2012; 35:1218-29. [PMID: 22512254 DOI: 10.1111/j.1460-9568.2012.08032.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prostaglandins are lipid-derived molecules that mediate the generation of fever in the central nervous system. In addition to their proinflammatory role, prostaglandins also impact neuronal development and synaptic plasticity, sometimes in a sex-specific manner. The cerebellum has a high expression of prostaglandin receptors during development, but the role that these molecules play during normal cerebellar maturation is unknown. We demonstrate here that disrupting prostaglandin synthesis with cyclo-oxygenase inhibitors during a time-sensitive window in early postnatal life alters cerebellar Purkinje cell development in rats, resulting in initially increased dendritic growth in both sexes. We show that this results in later cerebellar atrophy in males only, resulting in a sex-specific loss of cerebellar volume. Further, although performance in motor tasks is spared, social interaction and the sensory threshold are altered in males developmentally exposed to cyclo-oxygenase inhibitors. This work demonstrates a previously unknown role for prostaglandins in cerebellar development and emphasizes the role that the cerebellum plays outside motor tasks, in cognitive and sensory domains that may help to explain its connection to complex neurodevelopmental disorders such as autism.
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Affiliation(s)
- Shannon L Dean
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Didonna A, Sussman J, Benetti F, Legname G. The role of Bax and caspase-3 in doppel-induced apoptosis of cerebellar granule cells. Prion 2012; 6:309-16. [PMID: 22561161 PMCID: PMC3399532 DOI: 10.4161/pri.20026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Doppel (Dpl) protein is a paralog of the prion protein (PrP) that shares 25% sequence similarity with the C-terminus of PrP, a common N-glycosylation site and a C-terminal signal peptide for attachment of a glycosylphophatidyl inositol anchor. Whereas PrPC is highly expressed in the central nervous system (CNS), Dpl is detected mostly in testes and its ectopic expression in the CNS leads to ataxia as well as Purkinje and granule cell degeneration in the cerebellum. The mechanism through which Dpl induces neurotoxicity is still debated. In the present work, primary neuronal cultures derived from postnatal cerebellar granule cells of wild-type and PrP-knockout FVB mice were used in order to investigate the molecular events that occur upon exposure to Dpl. Treatment of cultured cerebellar neurons with recombinant Dpl produced apoptosis that could be prevented by PrP co-incubation. When primary neuronal cultures from Bax-deficient mice were incubated with Dpl, no apoptosis was observed, suggesting an important role of Bax in triggering neurodegeneration. Similarly, cell survival increased when recDpl-treated cells were incubated with an inhibitor of caspase-3, which mediates apoptosis in mammalian cells. Together, our findings raise the possibility that Bax and caspase-3 feature in Dpl-mediated apoptosis.
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Affiliation(s)
- Alessandro Didonna
- Neurobiology Sector, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
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Blaise S, Kneib M, Rousseau A, Gambino F, Chenard MP, Messadeq N, Muckenstrum M, Alpy F, Tomasetto C, Humeau Y, Rio MC. In vivo evidence that TRAF4 is required for central nervous system myelin homeostasis. PLoS One 2012; 7:e30917. [PMID: 22363515 PMCID: PMC3281907 DOI: 10.1371/journal.pone.0030917] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 12/29/2011] [Indexed: 01/22/2023] Open
Abstract
Tumor Necrosis Factor Receptor-Associated Factors (TRAFs) are major signal transducers for the TNF and interleukin-1/Toll-like receptor superfamilies. However, TRAF4 does not fit the paradigm of TRAF function in immune and inflammatory responses. Its physiological and molecular functions remain poorly understood. Behavorial analyses show that TRAF4-deficient mice (TRAF4-KO) exhibit altered locomotion coordination typical of ataxia. TRAF4-KO central nervous system (CNS) ultrastructure shows strong myelin perturbation including disorganized layers and disturbances in paranode organization. TRAF4 was previously reported to be expressed by CNS neurons. Using primary cell culture, we now show that TRAF4 is also expressed by oligodendrocytes, at all stages of their differentiation. Moreover, histology and electron microscopy show degeneration of a high number of Purkinje cells in TRAF4-KO mice, that was confirmed by increased expression of the Bax pro-apoptotic marker (immunofluorescence), TUNEL analysis, and caspase-3 activation and PARP1 cleavage (western blotting). Consistent with this phenotype, MAG and NogoA, two myelin-induced neurite outgrowth inhibitors, and their neuron partners, NgR and p75NTR were overexpressed (Q-RT-PCR and western blotting). The strong increased phosphorylation of Rock2, a RhoA downstream target, indicated that the NgR/p75NTR/RhoA signaling pathway, known to induce actin cytoskeleton rearrangement that favors axon regeneration inhibition and neuron apoptosis, is activated in the absence of TRAF4 (western blotting). Altogether, these results provide conclusive evidence for the pivotal contribution of TRAF4 to myelination and to cerebellar homeostasis, and link the loss of TRAF4 function to demyelinating or neurodegenerative diseases.
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Affiliation(s)
- Sébastien Blaise
- Functional Genomics and Cancer Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, Illkirch, France
| | - Marie Kneib
- Centre National de la Recherche Scientifique UPR3212, Strasbourg, France
| | - Adrien Rousseau
- Functional Genomics and Cancer Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, Illkirch, France
| | - Frederic Gambino
- Centre National de la Recherche Scientifique UPR3212, Strasbourg, France
| | - Marie-Pierre Chenard
- Département de Pathologie, Centre Hospitalier Universitaire de Hautepierre, Strasbourg, France
| | - Nadia Messadeq
- Functional Genomics and Cancer Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, Illkirch, France
| | - Martine Muckenstrum
- Département de Pathologie, Centre Hospitalier Universitaire de Hautepierre, Strasbourg, France
| | - Fabien Alpy
- Functional Genomics and Cancer Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, Illkirch, France
| | - Catherine Tomasetto
- Functional Genomics and Cancer Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, Illkirch, France
| | - Yann Humeau
- Centre National de la Recherche Scientifique UPR3212, Strasbourg, France
| | - Marie-Christine Rio
- Functional Genomics and Cancer Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR7104, Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, Illkirch, France
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Gawinecka J, Dieks J, Asif AR, Carimalo J, Heinemann U, Streich JH, Dihazi H, Schulz-Schaeffer W, Zerr I. Codon 129 polymorphism specific cerebrospinal fluid proteome pattern in sporadic Creutzfeldt-Jakob disease and the implication of glycolytic enzymes in prion-induced pathology. J Proteome Res 2010; 9:5646-57. [PMID: 20866111 DOI: 10.1021/pr1004604] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cerebrospinal fluid (CSF) contains a dynamic and complex mixture of proteins, which can reflect a physiological and pathological state of the central nervous system. In our present study, we show CSF protein patterns from patients with the two most frequent subtypes of sporadic Creutzfeldt-Jakob disease (sCJD) defined by the codon 129 genotype (MM, MV, and VV) and the protease-resistant form of prion protein (type 1 and type 2). The densitometric analysis of 2D gels showed up-regulation of 27 and down-regulation of 3 proteins in the MM-sCJD as well as the up-regulation of 24 proteins in the VV-sCJD as compared to nondemented control. Almost 40% of sCJD specific regulated proteins in CSF are involved in glucose metabolism, regardless of the codon 129 polymorphism. The increase in CSF levels of lactate dehydrogenase (LDH), glucose-6-phosphate isomerase (G6PI), and fructose-bisphosphate aldolase A (ALDOA) were validated on a larger group of sCJD patients including three possible codon 129 polymorphism carriers and three control groups consisting of nondemented, neurological cases as well as patients suffering from Alzheimer's disease or vascular dementia. Subsequently, the abundance of these glycolytic enzymes in the brain as well as their cellular localization were determined. This study demonstrates for the first time the implication of G6PI in prion-induced pathology as well as its cellular translocalization in sCJD. The identification of sCJD-regulated proteins in CSF of living symptomatic patients in our study can broaden our knowledge about pathological processes occurring in sCJD, as they are still not fully understood.
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Affiliation(s)
- Joanna Gawinecka
- Department of Clinical Chemistry, Medical Center Georg-August University, Goettingen, Germany
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Cell Death as a Regulator of Cerebellar Histogenesis and Compartmentation. THE CEREBELLUM 2010; 10:373-92. [DOI: 10.1007/s12311-010-0222-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Christensen HM, Dikranian K, Li A, Baysac KC, Walls KC, Olney JW, Roth KA, Harris DA. A highly toxic cellular prion protein induces a novel, nonapoptotic form of neuronal death. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:2695-706. [PMID: 20472884 DOI: 10.2353/ajpath.2010.091007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Several different deletions within the N-terminal tail of the prion protein (PrP) induce massive neuronal death when expressed in transgenic mice. This toxicity is dose-dependently suppressed by coexpression of full-length PrP, suggesting that it results from subversion of a normal physiological activity of cellular PrP. We performed a combined biochemical and morphological analysis of Tg(DeltaCR) mice, which express PrP carrying a 21-aa deletion (residues 105-125) within a highly conserved region of the protein. Death of cerebellar granule neurons in Tg(DeltaCR) mice is not accompanied by activation of either caspase-3 or caspase-8 or by increased levels of the autophagy marker, LC3-II. In electron micrographs, degenerating granule neurons displayed a unique morphology characterized by heterogeneous condensation of the nuclear matrix without formation of discrete chromatin masses typical of neuronal apoptosis. Our data demonstrate that perturbations in PrP functional activity induce a novel, nonapoptotic, nonautophagic form of neuronal death whose morphological features are reminiscent of those associated with excitotoxic stress.
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Affiliation(s)
- Heather M Christensen
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
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9
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Heitz S, Grant NJ, Leschiera R, Haeberlé A, Demais V, Bombarde G, Bailly Y. Autophagy and cell death of Purkinje cells overexpressing Doppel in Ngsk Prnp-deficient mice. Brain Pathol 2010; 20:119-32. [PMID: 19055638 PMCID: PMC8094811 DOI: 10.1111/j.1750-3639.2008.00245.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2008] [Accepted: 10/22/2008] [Indexed: 01/09/2023] Open
Abstract
In Ngsk prion protein (PrP)-deficient mice (NP(0/0)), ectopic expression of PrP-like protein Doppel (Dpl) in central neurons induces significant Purkinje cell (PC) death resulting in late-onset ataxia. NP(0/0) PC death is partly prevented by either knocking-out the apoptotic factor BAX or overexpressing the anti-apoptotic factor BCL-2 suggesting that apoptosis is involved in Dpl-induced death. In this study, Western blotting and immunohistofluorescence show that both before and during significant PC loss, the scrapie-responsive gene 1 (Scrg1)--potentially associated with autophagy--and the autophagic markers LC3B and p62 increased in the NP(0/0) PCs whereas RT-PCR shows stable mRNA expression, suggesting that the degradation of autophagic products is impaired in NP(0/0) PCs. At the ultrastructural level, autophagic-like profiles accumulated in somatodendritic and axonal compartments of NP(0/0), but not wild-type PCs. The most robust autophagy was observed in NP(0/0) PC axon compartments in the deep cerebellar nuclei suggesting that it is initiated in these axons. Our previous and present data indicate that Dpl triggers autophagy and apoptosis in NP(0/0) PCs. As observed in amyloid neurodegenerative diseases, upregulation of autophagic markers as well as extensive accumulation of autophagosomes in NP(0/0) PCs are likely to reflect a progressive dysfunction of autophagy that could trigger apoptotic cascades.
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Affiliation(s)
- Stéphane Heitz
- Institut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, UMR7168‐LC2 CNRS and Université Louis Pasteur, Strasbourg, France
| | - Nancy J. Grant
- Institut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, UMR7168‐LC2 CNRS and Université Louis Pasteur, Strasbourg, France
| | - Raphael Leschiera
- Institut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, UMR7168‐LC2 CNRS and Université Louis Pasteur, Strasbourg, France
| | - Anne‐Marie Haeberlé
- Institut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, UMR7168‐LC2 CNRS and Université Louis Pasteur, Strasbourg, France
| | - Valérie Demais
- Plateforme d'Imagerie in vitro, IFR 37 de Neurosciences, Strasbourg, France
| | - Guy Bombarde
- Institut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, UMR7168‐LC2 CNRS and Université Louis Pasteur, Strasbourg, France
| | - Yannick Bailly
- Institut des Neurosciences Cellulaires et Intégratives, Département Neurotransmission et Sécrétion Neuroendocrine, UMR7168‐LC2 CNRS and Université Louis Pasteur, Strasbourg, France
- Plateforme d'Imagerie in vitro, IFR 37 de Neurosciences, Strasbourg, France
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New insights into cellular prion protein (PrPc) functions: the "ying and yang" of a relevant protein. ACTA ACUST UNITED AC 2009; 61:170-84. [PMID: 19523487 DOI: 10.1016/j.brainresrev.2009.06.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 05/26/2009] [Accepted: 06/03/2009] [Indexed: 12/19/2022]
Abstract
The conversion of cellular prion protein (PrP(c)), a GPI-anchored protein, into a protease-K-resistant and infective form (generally termed PrP(sc)) is mainly responsible for Transmissible Spongiform Encephalopathies (TSEs), characterized by neuronal degeneration and progressive loss of basic brain functions. Although PrP(c) is expressed by a wide range of tissues throughout the body, the complete repertoire of its functions has not been fully determined. Recent studies have confirmed its participation in basic physiological processes such as cell proliferation and the regulation of cellular homeostasis. Other studies indicate that PrP(c) interacts with several molecules to activate signaling cascades with a high number of cellular effects. To determine PrP(c) functions, transgenic mouse models have been generated in the last decade. In particular, mice lacking specific domains of the PrP(c) protein have revealed the contribution of these domains to neurodegenerative processes. A dual role of PrP(c) has been shown, since most authors report protective roles for this protein while others describe pro-apoptotic functions. In this review, we summarize new findings on PrP(c) functions, especially those related to neural degeneration and cell signaling.
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Lin DTS, Jodoin J, Baril M, Goodyer CG, Leblanc AC. Cytosolic prion protein is the predominant anti-Bax prion protein form: exclusion of transmembrane and secreted prion protein forms in the anti-Bax function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2001-12. [PMID: 18590778 DOI: 10.1016/j.bbamcr.2008.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 05/06/2008] [Accepted: 05/27/2008] [Indexed: 01/01/2023]
Abstract
Prion protein (PrP) prevents Bax-mediated cell death by inhibiting the initial Bax conformational change that converts cytosolic Bax into a pro-apoptotic protein. PrP is mostly a glycophosphatidylinositol-anchored cell surface protein but it is also retrotranslocated into cytosolic PrP (CyPrP) or can become a type 1 or type 2 transmembrane protein. To determine the form and subcellular location of the PrP that has anti-Bax function, we co-expressed various Syrian hamster PrP (SHaPrP) mutants that favour specific PrP topologies and subcellular localization with N-terminally green fluorescent protein tagged pro-apoptotic Bax (EGFP-Bax) in MCF-7 cells and primary human neurons. Mutants that generate both CyPrP and secreted PrP ((Sec)PrP) or only CyPrP have anti-Bax activity. Mutants that produce (Ctm)PrP or (Ntm)PrP lose the anti-Bax activity, despite their ability to also make (Sec)PrP. Transmembrane-generating mutants do not produce CyPrP and both normal and cognate mutant forms of CyPrP rescue against the loss of anti-Bax activity. (Sec)PrP-generating constructs also produce non-membrane attached (Sec)PrP. However, this form of PrP has minimal anti-Bax activity. We conclude that CyPrP is the predominant form of PrP with anti-Bax function. These results imply that the retrotranslocation of PrP encompasses a survival function and is not merely a pathway for the proteasomal degradation of misfolded protein.
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Affiliation(s)
- David T S Lin
- Bloomfield Center for Research in Aging, LDI, Montréal, QC, Canada H3T 1E2
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Steele AD, Hetz C, Yi CH, Jackson WS, Borkowski AW, Yuan J, Wollmann RH, Lindquist S. Prion pathogenesis is independent of caspase-12. Prion 2007; 1:243-7. [PMID: 19164919 PMCID: PMC2634538 DOI: 10.4161/pri.1.4.5551] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The pathogenic mechanism(s) underlying neurodegenerative diseases associated with protein misfolding is unclear. Several studies have implicated ER stress pathways in neurodegenerative conditions, including prion disease, amyotrophic lateral sclerosis, Alzheimer's disease and many others. The ER stress response and upregulation of ER stress-responsive chaperones is observed in the brains of patients affected with Creutzfeldt-Jacob disease and in mouse models of prion diseases. In particular, the processing of caspase-12, an ER-localized caspase, correlates with neuronal cell death in prion disease. However, the contribution of caspase-12 to neurodegeneration has not been directly addressed in vivo. We confirm that ER stress is induced and that caspase-12 is proteolytically processed in a murine model of infectious prion disease. To address the causality of caspase-12 in mediating infectious prion pathogenesis, we inoculated mice deficient in caspase-12 with prions. The survival, behavior, pathology and accumulation of proteinase K-resistant PrP are indistinguishable between caspase-12 knockout and control mice, suggesting that caspase-12 is not necessary for mediating the neurotoxic effects of prion protein misfolding.
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Affiliation(s)
- Andrew D Steele
- Whitehead Institute for Biomedical Research, Howard Hughes Medical Institute, Massachusets Institute of Technology, Cambridge Massachusetts 02142, USA
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