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Xuan Q, Zhang YX, Liu DG, Chan P, Xu SL, Cui YQ. Post-translational modifications of α-synuclein contribute to neurodegeneration in the colon of elderly individuals. Mol Med Rep 2016; 13:5077-83. [PMID: 27109489 PMCID: PMC4878562 DOI: 10.3892/mmr.2016.5166] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 02/23/2016] [Indexed: 01/24/2023] Open
Abstract
Synucleinopathies and abnormalities in the nerves of the enteric nervous system are hypothesized to be involved in age-associated motility disorders. The aim of the present study was to investigate the expression of various antigens, including α‑synuclein (Syn) and its post‑translational modified forms, in the human colon at various ages. In addition, the study aimed to correlate the expression of Syn with neurodegeneration. Immunohistochemistry was used to detect the expression of neurofilament (NF), Syn, as well as its nitrated (N) form in the healthy colonic tissue of 12 young (34.08±5.12 years), 10 middle‑aged (51.80±3.52 years), and 11 elderly (75.82±7.70 years) individuals. To the best of our knowledge, the current study is the first to demonstrate the presence of N‑Syn in the colonic tissue. N‑Syn was identified in the upper layer of the mucosa and submucosa layer. Furthermore, Syn (wild‑type) was present in the mucosa and submucosa. The number of NF‑positive neurons in the submucosal layer declined significantly with age (P<0.01). In addition, Syn and N‑Syn significantly increased during aging (P<0.01). Furthermore, a negative correlation was identified between neuron number and synucleinopathies, indicating the abnormal accumulation of both wild-type Syn and N‑Syn in the mucosa, submucosa, muscle layer and myenteric plexus. The present study demonstrates that the Syn pathology may be linked to colic neuronal degeneration during normal aging, and this link may cause functional deficits.
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Affiliation(s)
- Qi Xuan
- Department of Nutrition, Xuanwu Hospital, Capital Medical University, Beijing 100053, P.R. China
| | - Yu-Xian Zhang
- Department of Internal Medicine, Beijing Moslem Hospital, Beijing 100054, P.R. China
| | - Dian-Gang Liu
- Department of General Surgery, Xuanwu Hospital, Capital Medical University, Beijing 100053, P.R. China
| | - Piu Chan
- Department of Neurobiology, Institute of Geriatrics of Beijing, Xuanwu Hospital, Capital Medical University, Key Laboratory for Neurodegenerative Disease of Ministry of Education, Beijing 100053, P.R. China
| | - Sheng-Li Xu
- Department of Neurobiology, Institute of Geriatrics of Beijing, Xuanwu Hospital, Capital Medical University, Key Laboratory for Neurodegenerative Disease of Ministry of Education, Beijing 100053, P.R. China
| | - Ye-Qing Cui
- Department of General Surgery, Xuanwu Hospital, Capital Medical University, Beijing 100053, P.R. China
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52
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Sustained Arginase 1 Expression Modulates Pathological Tau Deposits in a Mouse Model of Tauopathy. J Neurosci 2016; 35:14842-60. [PMID: 26538654 DOI: 10.1523/jneurosci.3959-14.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Tau accumulation remains one of the closest correlates of neuronal loss in Alzheimer's disease. In addition, tau associates with several other neurodegenerative diseases, collectively known as tauopathies, in which clinical phenotypes manifest as cognitive impairment, behavioral disturbances, and motor impairment. Polyamines act as bivalent regulators of cellular function and are involved in numerous biological processes. The regulation of the polyamines system can become dysfunctional during disease states. Arginase 1 (Arg1) and nitric oxide synthases compete for l-arginine to produce either polyamines or nitric oxide, respectively. Herein, we show that overexpression of Arg1 using adeno-associated virus (AAV) in the CNS of rTg4510 tau transgenic mice significantly reduced phospho-tau species and tangle pathology. Sustained Arg1 overexpression decreased several kinases capable of phosphorylating tau, decreased inflammation, and modulated changes in the mammalian target of rapamycin and related proteins, suggesting activation of autophagy. Arg1 overexpression also mitigated hippocampal atrophy in tau transgenic mice. Conversely, conditional deletion of Arg1 in myeloid cells resulted in increased tau accumulation relative to Arg1-sufficient mice after transduction with a recombinant AAV-tau construct. These data suggest that Arg1 and the polyamine pathway may offer novel therapeutic targets for tauopathies.
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53
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Abstract
The major challenge for progressive multiple sclerosis therapy is the promotion of remyelination from inflammation-induced demyelination. A switch from an M1- to an M2-dominant polarization of microglia is critical in these repair processes. In this study, we identified the homeobox gene msh-like homeobox-3 (Msx3) as a new pivotal regulator for microglial polarization. MSX3 was induced during microglia M2 polarization and repressed in M1 cells. The expression of MSX3 in microglia was dynamically regulated during experimental autoimmune encephalomyelitis (EAE), which is an animal model of multiple sclerosis. The overexpression of MSX3 in microglia promoted M2 but impeded M1 polarization. Interrupting MSX3 expression in microglia accelerated inflammation-induced demyelination and neurodegeneration. The conditioned medium from MSX3-transduced microglia promoted oligodendrocyte progenitor survival, differentiation, and neurite outgrowth. The adoptive transfer of MSX3-transduced microglia suppressed EAE and facilitated remyelination within the murine CNS in EAE and the LPC model. Mechanically, chromatin immunoprecipitation assays also indicated that MSX3 directly regulated three key genes associated with microglia M2 polarization, including Pparg, Stat6, and Jak3. Importantly, we found that overexpression of MSX3 in human-derived microglia represents the M2 phenotype and ameliorated EAE after intraventricular injection. Our findings suggest a new homeobox protein-dependent mechanism for driving microglia M2 polarization and identify MSX3 as an attractive therapeutic approach for preventing inflammation-induced demyelination and promoting remyelination.
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54
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Regulation of the Neurodegenerative Process Associated to Parkinson's Disease by CD4+ T-cells. J Neuroimmune Pharmacol 2015; 10:561-75. [PMID: 26018603 DOI: 10.1007/s11481-015-9618-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/19/2015] [Indexed: 01/09/2023]
Abstract
Neuroinflammation constitutes a fundamental process involved in the physiopathology of Parkinson's disease (PD). Microglial cells play a central role in the outcome of neuroinflammation and consequent neurodegeneration of dopaminergic neurons in the substantia nigra. Current evidence indicates that CD4+ T-cells infiltrate the central nervous system (CNS) in PD, where they play a critical role determining the functional phenotype of microglia, thus regulating the progression of the neurodegenerative process. Here, we first analysed the pathogenic role of inflammatory phenotypes and the beneficial role of anti-inflammatory phenotypes of encephalitogenic CD4+ T-cells involved in the physiopathology of PD. Next, we discussed how alterations of neurotransmitter levels observed in the basal ganglia throughout the time course of PD progression could be strongly affecting the behaviour of encephalitogenic CD4+ T-cells and thereby the outcome of the neuroinflammatory process and the consequent neurodegeneration of dopaminergic neurons. Afterward, we integrated the evidence indicating the involvement of an antigen-specific immune response mediated by T-cells and B-cells against CNS-derived self-constituents in PD. Consistent with the involvement of a relevant autoimmune component in PD, we also reviewed the polymorphisms of both, class I and class II major histocompatibility complexes, associated to the risk of PD. Overall, this study gives an overview of how an autoimmune component involved in PD plays a fundamental role in the progression of the neurodegenerative process.
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55
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Lopes da Fonseca T, Villar-Piqué A, Outeiro TF. The Interplay between Alpha-Synuclein Clearance and Spreading. Biomolecules 2015; 5:435-71. [PMID: 25874605 PMCID: PMC4496680 DOI: 10.3390/biom5020435] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 12/23/2022] Open
Abstract
Parkinson's Disease (PD) is a complex neurodegenerative disorder classically characterized by movement impairment. Pathologically, the most striking features of PD are the loss of dopaminergic neurons and the presence of intraneuronal protein inclusions primarily composed of alpha-synuclein (α-syn) that are known as Lewy bodies and Lewy neurites in surviving neurons. Though the mechanisms underlying the progression of PD pathology are unclear, accumulating evidence suggests a prion-like spreading of α-syn pathology. The intracellular homeostasis of α-syn requires the proper degradation of the protein by three mechanisms: chaperone-mediated autophagy, macroautophagy and ubiquitin-proteasome. Impairment of these pathways might drive the system towards an alternative clearance mechanism that could involve its release from the cell. This increased release to the extracellular space could be the basis for α-syn propagation to different brain areas and, ultimately, for the spreading of pathology and disease progression. Here, we review the interplay between α-syn degradation pathways and its intercellular spreading. The understanding of this interplay is indispensable for obtaining a better knowledge of the molecular basis of PD and, consequently, for the design of novel avenues for therapeutic intervention.
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Affiliation(s)
- Tomás Lopes da Fonseca
- Department of Neurodegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen 37073, Germany.
- Instituto de Fisiologia, Faculty of Medicine, University of Lisbon, Lisboa 1649-028, Portugal.
| | - Anna Villar-Piqué
- Department of Neurodegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen 37073, Germany.
| | - Tiago Fleming Outeiro
- Department of Neurodegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen 37073, Germany.
- Instituto de Fisiologia, Faculty of Medicine, University of Lisbon, Lisboa 1649-028, Portugal.
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa 1150, Portugal.
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56
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Burai R, Ait-Bouziad N, Chiki A, Lashuel HA. Elucidating the Role of Site-Specific Nitration of α-Synuclein in the Pathogenesis of Parkinson's Disease via Protein Semisynthesis and Mutagenesis. J Am Chem Soc 2015; 137:5041-52. [PMID: 25768729 DOI: 10.1021/ja5131726] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra and the presence of intraneuronal inclusions consisting of aggregated and post-translationally modified α-synuclein (α-syn). Despite advances in the chemical synthesis of α-syn and other proteins, the generation of site-specifically nitrated synthetic proteins has not been reported. Consequently, it has not been possible to determine the roles of nitration at specific residues in regulating the physiological and pathogenic properties of α-syn. Here we report, for the first time, the site-specific incorporation of 3-nitrotyrosine at different regions of α-syn using native chemical ligation combined with a novel desulfurization strategy. This strategy enabled us to investigate the role of nitration at single or multiple tyrosine residues in regulating α-syn structure, membrane binding, oligomerization, and fibrils formation. We demonstrate that different site-specifically nitrated α-syn species exhibit distinct structural and aggregation properties and exhibit reduced affinity to negatively charged vesicle membranes. We provide evidence that intermolecular interactions between the N- and C-terminal regions of α-syn play critical roles in mediating nitration-induced α-syn oligomerization. For example, when Y39 is not available for nitration (Y39F and Y39/125F), the extent of cross-linking is limited mostly to dimer formation, whereas mutants in which Y39 along with one or multiple C-terminal tyrosines (Y125F, Y133F, Y136F and Y133/136F) can still undergo nitration readily to form higher-order oligomers. Our semisynthetic strategy for generating site-specifically nitrated proteins opens up new possibilities for investigating the role of nitration in regulating protein structure and function in health and disease.
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Affiliation(s)
- Ritwik Burai
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nadine Ait-Bouziad
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Anass Chiki
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Hilal A Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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57
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Cebrián C, Loike JD, Sulzer D. Neuroinflammation in Parkinson's disease animal models: a cell stress response or a step in neurodegeneration? Curr Top Behav Neurosci 2015; 22:237-270. [PMID: 25293443 DOI: 10.1007/7854_2014_356] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The motor symptoms of Parkinson's disease are due to the progressive degeneration of dopaminergic neurons in the substantia nigra. Multiple neuroinflammatory processes are exacerbated in Parkinson's disease, including glial-mediated reactions, increased expression of proinflammatory substances, and lymphocytic infiltration, particularly in the substantia nigra. Neuroinflammation is also implicated in the neurodegeneration and consequent behavioral symptoms of many Parkinson's disease animal models, although it is not clear whether these features emulate pathogenic steps in the genuine disorder or if some inflammatory features provide protective stress responses. Here, we compare and summarize findings on neuroinflammatory responses and effects on behavior in a wide range of toxin-based, inflammatory and genetic Parkinson's disease animal models.
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Affiliation(s)
- Carolina Cebrián
- Department of Neurology, Columbia University Medical Center, New York, NY, 10032, USA
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58
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Allen Reish HE, Standaert DG. Role of α-synuclein in inducing innate and adaptive immunity in Parkinson disease. JOURNAL OF PARKINSON'S DISEASE 2015; 5:1-19. [PMID: 25588354 PMCID: PMC4405142 DOI: 10.3233/jpd-140491] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alpha-synuclein (α-syn) is central to the pathogenesis of Parkinson disease (PD). Gene duplications, triplications and point mutations in SNCA1, the gene encoding α-syn, cause autosomal dominant forms of PD. Aggregated and post-translationally modified forms of α-syn are present in Lewy bodies and Lewy neurites in both sporadic and familial PD, and recent work has emphasized the prion-like ability of aggregated α-syn to produce spreading pathology. Accumulation of abnormal forms of α-syn is a trigger for PD, but recent evidence suggests that much of the downstream neurodegeneration may result from inflammatory responses. Components of both the innate and adaptive immune systems are activated in PD, and influencing interactions between innate and adaptive immune components has been shown to modify the pathological process in animal models of PD. Understanding the relationship between α-syn and subsequent inflammation may reveal novel targets for neuroprotective interventions. In this review, we examine the role of α-syn and modified forms of this protein in the initiation of innate and adaptive immune responses.
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Affiliation(s)
- Heather E Allen Reish
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, Alabama, USA
| | - David G Standaert
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, University of Alabama at Birmingham, Alabama, USA
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59
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González H, Elgueta D, Montoya A, Pacheco R. Neuroimmune regulation of microglial activity involved in neuroinflammation and neurodegenerative diseases. J Neuroimmunol 2014; 274:1-13. [PMID: 25091432 DOI: 10.1016/j.jneuroim.2014.07.012] [Citation(s) in RCA: 242] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/27/2014] [Accepted: 07/16/2014] [Indexed: 11/18/2022]
Abstract
Neuroinflammation constitutes a fundamental process involved in the progression of several neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis and multiple sclerosis. Microglial cells play a central role in neuroinflammation, promoting neuroprotective or neurotoxic microenvironments, thus controlling neuronal fate. Acquisition of different microglial functions is regulated by intercellular interactions with neurons, astrocytes, the blood-brain barrier, and T-cells infiltrating the central nervous system. In this study, an overview of the regulation of microglial function mediated by different intercellular communications is summarised and discussed. Afterward, we focus in T-cell-mediated regulation of neuroinflammation involved in neurodegenerative disorders.
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Affiliation(s)
- Hugo González
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Ñuñoa 7780272, Santiago, Chile
| | - Daniela Elgueta
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Ñuñoa 7780272, Santiago, Chile; Facultad de Ciencias Biológicas, Universidad Andrés Bello, 8370146 Santiago, Chile
| | - Andro Montoya
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Ñuñoa 7780272, Santiago, Chile
| | - Rodrigo Pacheco
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Ñuñoa 7780272, Santiago, Chile; Programa de Biomedicina, Universidad San Sebastián, Ñuñoa 7780272, Santiago, Chile.
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60
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Romero-Ramos M, von Euler Chelpin M, Sanchez-Guajardo V. Vaccination strategies for Parkinson disease: induction of a swift attack or raising tolerance? Hum Vaccin Immunother 2014; 10:852-67. [PMID: 24670306 DOI: 10.4161/hv.28578] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Parkinson disease is the second most common neurodegenerative disease in the world, but there is currently no available cure for it. Current treatments only alleviate some of the symptoms for a few years, but they become ineffective in the long run and do not stop the disease. Therefore it is of outmost importance to develop therapeutic strategies that can prevent, stop, or cure Parkinson disease. A very promising target for these therapies is the peripheral immune system due to its probable involvement in the disease and its potential as a tool to modulate neuroinflammation. But for such strategies to be successful, we need to understand the particular state of the peripheral immune system during Parkinson disease in order to avoid its weaknesses. In this review we examine the available data regarding how dopamine regulates the peripheral immune system and how this regulation is affected in Parkinson disease; the specific cytokine profiles observed during disease progression and the alterations documented to date in patients' peripheral blood mononuclear cells. We also review the different strategies used in Parkinson disease animal models to modulate the adaptive immune response to salvage dopaminergic neurons from cell death. After analyzing the evidence, we hypothesize the need to prime the immune system to restore natural tolerance against α-synuclein in Parkinson disease, including at the same time B and T cells, so that T cells can reprogram microglia activation to a beneficial pattern and B cell/IgG can help neurons cope with the pathological forms of α-synuclein.
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Affiliation(s)
- Marina Romero-Ramos
- CNS disease modeling group; Department of Biomedicine; Aarhus University; Aarhus, Denmark; NEURODIN; Department of Biomedicine; Aarhus University; Aarhus, Denmark
| | - Marianne von Euler Chelpin
- CNS disease modeling group; Department of Biomedicine; Aarhus University; Aarhus, Denmark; NEURODIN; Department of Biomedicine; Aarhus University; Aarhus, Denmark; Neuroimmunology of Degenerative Diseases group; Department of Biomedicine; Aarhus University; Aarhus, Denmark
| | - Vanesa Sanchez-Guajardo
- NEURODIN; Department of Biomedicine; Aarhus University; Aarhus, Denmark; Neuroimmunology of Degenerative Diseases group; Department of Biomedicine; Aarhus University; Aarhus, Denmark
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61
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Jensen SK, Yong VW. Microglial modulation as a mechanism behind the promotion of central nervous system well-being by physical exercise. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/cen3.12093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Samuel K. Jensen
- Hotchkiss Brain Institute and the Department of Clinical Neurosciences; University of Calgary; Calgary AB Canada
| | - V. Wee Yong
- Hotchkiss Brain Institute and the Department of Clinical Neurosciences; University of Calgary; Calgary AB Canada
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62
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Sathiya S, Ranju V, Kalaivani P, Priya RJ, Sumathy H, Sunil AG, Babu CS. Telmisartan attenuates MPTP induced dopaminergic degeneration and motor dysfunction through regulation of α-synuclein and neurotrophic factors (BDNF and GDNF) expression in C57BL/6J mice. Neuropharmacology 2013; 73:98-110. [DOI: 10.1016/j.neuropharm.2013.05.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 04/18/2013] [Accepted: 05/27/2013] [Indexed: 12/20/2022]
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Roy A, Pahan K. Ankyrin repeat and BTB/POZ domain containing protein-2 inhibits the aggregation of alpha-synuclein: implications for Parkinson's disease. FEBS Lett 2013; 587:3567-74. [PMID: 24076025 DOI: 10.1016/j.febslet.2013.09.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 09/12/2013] [Accepted: 09/13/2013] [Indexed: 01/17/2023]
Abstract
Aggregation of α-synuclein is a pathological hallmark of sporadic or familial PD. However, the detailed molecular mechanism responsible for the aggregation of α-synuclein has not been properly explored. In the present study, we have identified a novel role of an anti-tumorigenic BTB/POZ domain containing protein-2 (BPOZ-2) in the regulation of α-synuclein accumulation in dopaminergic (DA) neurons. MPP(+), an etiological factor for PD, significantly downregulated the expression of BPOZ-2 ahead of α-synuclein upregulation. Moreover, siRNA knockdown of BPOZ-2 alone stimulated the aggregation of α-synuclein protein; the effect was further induced in presence of MPP(+) in mouse primary DA neurons. Finally, the absence of BPOZ-2 in α-synuclein expressing neuronal populations of MPTP-intoxicated mouse and primate nigra indicates that the suppression of BPOZ-2 could be involved in the accumulation of α-synuclein protein.
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Affiliation(s)
- Avik Roy
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA.
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Xiang W, Schlachetzki JC, Helling S, Bussmann JC, Berlinghof M, Schäffer TE, Marcus K, Winkler J, Klucken J, Becker CM. Oxidative stress-induced posttranslational modifications of alpha-synuclein: Specific modification of alpha-synuclein by 4-hydroxy-2-nonenal increases dopaminergic toxicity. Mol Cell Neurosci 2013; 54:71-83. [DOI: 10.1016/j.mcn.2013.01.004] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/28/2012] [Accepted: 01/19/2013] [Indexed: 01/24/2023] Open
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65
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Sanchez-Guajardo V, Barnum C, Tansey M, Romero-Ramos M. Neuroimmunological processes in Parkinson's disease and their relation to α-synuclein: microglia as the referee between neuronal processes and peripheral immunity. ASN Neuro 2013; 5:113-39. [PMID: 23506036 PMCID: PMC3639751 DOI: 10.1042/an20120066] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 12/15/2022] Open
Abstract
The role of neuroinflammation and the adaptive immune system in PD (Parkinson's disease) has been the subject of intense investigation in recent years, both in animal models of parkinsonism and in post-mortem PD brains. However, how these processes relate to and modulate α-syn (α-synuclein) pathology and microglia activation is still poorly understood. Specifically, how the peripheral immune system interacts, regulates and/or is induced by neuroinflammatory processes taking place during PD is still undetermined. We present herein a comprehensive review of the features and impact that neuroinflamation has on neurodegeneration in different animal models of nigral cell death, how this neuroinflammation relates to microglia activation and the way microglia respond to α-syn in vivo. We also discuss a possible role for the peripheral immune system in animal models of parkinsonism, how these findings relate to the state of microglia activation observed in these animal models and how these findings compare with what has been observed in humans with PD. Together, the available data points to the need for development of dual therapeutic strategies that modulate microglia activation to change not only the way microglia interact with the peripheral immune system, but also to modulate the manner in which microglia respond to encounters with α-syn. Lastly, we discuss the immune-modulatory strategies currently under investigation in animal models of parkinsonism and the degree to which one might expect their outcomes to translate faithfully to a clinical setting.
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Key Words
- lymphocytes
- m1/m2 phenotype
- microglia
- neuroinflammation
- parkinson’s disease
- α-synuclein
- 6-ohda, 6-hydroxydopamine
- ad, alzheimer’s disease
- apc, antigen-presenting cell
- α-syn, α-synuclein
- bbb, brain–blood barrier
- bcg, bacille calmette–guérin
- bm, bone marrow
- cfa, complete freund’s adjuvant
- cm, conditioned media
- cns, central nervous system
- cox, cyclooxygenase
- cr, complement receptor
- csf, cerebrospinal fluid
- da, dopamine
- eae, experimental autoimmune encephalomyelitis
- ga, galatiramer acetate
- gdnf, glial-derived neurotrophic factor
- gfp, green fluorescent protein
- hla-dr, human leucocyte antigen type dr
- ifnγ, interferon γ
- igg, immunoglobulin g
- il, interleukin
- inos, inducible nitric oxide synthase
- lamp, lysosome-associated membrane protein
- lb, lewy body
- lps, lipopolysaccharide
- mhc, major histocompatibility complex
- mptp, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine
- nfκb, nuclear factor κb
- nk, natural killer
- no, nitric oxide
- pd, parkinson’s disease
- pet, positron-emission tomography
- prp, prion protein
- raav, recombinant adeno-associated virus
- rns, reactive nitrogen species
- ros, reactive oxygen species
- sn, substantia nigra
- snp, single nucleotide polymorphism
- tcr, t-cell receptor
- tgfβ, tumour growth factor β
- th, tyrosine hydroxylase
- th1, t helper 1
- tlr, toll-like receptor
- tnf, tumour necrosis factor
- treg, regulatory t-cell
- vip, vasoactive intestinal peptide
- wt, wild-type
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Affiliation(s)
- Vanesa Sanchez-Guajardo
- *CNS Disease Modeling Group, Department of Biomedicine, Ole Worms Allé 3,
Aarhus University, DK-8000 Aarhus C, Denmark
| | - Christopher J. Barnum
- †Department of Physiology, Emory University, School of Medicine, Atlanta, GA
30233, U.S.A
| | - Malú G. Tansey
- †Department of Physiology, Emory University, School of Medicine, Atlanta, GA
30233, U.S.A
| | - Marina Romero-Ramos
- *CNS Disease Modeling Group, Department of Biomedicine, Ole Worms Allé 3,
Aarhus University, DK-8000 Aarhus C, Denmark
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Ser129D mutant alpha-synuclein induces earlier motor dysfunction while S129A results in distinctive pathology in a rat model of Parkinson's disease. Neurobiol Dis 2013; 56:47-58. [PMID: 23567651 DOI: 10.1016/j.nbd.2013.03.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 03/19/2013] [Accepted: 03/26/2013] [Indexed: 02/04/2023] Open
Abstract
Alpha-synuclein phosphorylated at serine 129 (S129) is highly elevated in Parkinson's disease patients where it mainly accumulates in the Lewy bodies. Several groups have studied the role of phosphorylation at the S129 in α-synuclein in a rat model for Parkinson's disease using recombinant adeno-associated viral (rAAV) vectors. The results obtained are inconsistent and accordingly the role of S129 phosphorylation in α-synuclein toxicity remains unclear. This prompted us to re-examine the neuropathological and behavioral effects of the S129 modified α-synuclein species in vivo. For this purpose, we used two mutated forms of human α-synuclein in which the S129 was replaced either with an alanine (S129A), to block phosphorylation, or with an aspartate (S129D), to mimic phosphorylation, and compared them with the wild type α-synuclein. This approach was similar in design to previous studies, however our investigation of dopaminergic degeneration also included performing a detailed study of the α-synuclein induced pathology in the striatum and the analysis of motor deficits. Our results showed that overexpressing S129D or wild type α-synuclein resulted in an accelerated dopaminergic fiber loss as compared with S129A α-synuclein. Furthermore, the motor deficit seen in the group treated with the mutant S129D α-synuclein appeared earlier than the other two forms of α-synuclein. Conversely, S129A α-synuclein showed significantly larger pathological α-synuclein-positive inclusions, and slower dopaminergic fiber loss, when compared to the other two forms of α-synuclein, suggesting a neuroprotective effect of the mutation. When examined at long-term, all three α-synuclein forms resulted in pathological accumulations of α-synuclein in striatal fibers and dopaminergic cell death in the substantia nigra. Our data show that changes in the S129 residue of α-synuclein influence the rate of pathology and neurodegeneration, with an overall deleterious effect of exchanging S129 to a residue mimicking its phosphorylated state.
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Jadhav S, Zilka N, Novak M. Protein truncation as a common denominator of human neurodegenerative foldopathies. Mol Neurobiol 2013; 48:516-32. [PMID: 23516100 DOI: 10.1007/s12035-013-8440-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 03/05/2013] [Indexed: 12/13/2022]
Abstract
Neurodegenerative foldopathies are characterized by aberrant folding of diseased modified proteins, which are major constituents of the intracellular and extracellular lesions. These lesions correlate with the cognitive and/or motor impairment seen in these diseases. The majority of the disease modified proteins in neurodegenerative foldopathies belongs to the group of proteins termed as intrinsically disordered proteins (IDPs). Several independent studies have showed that abnormal protein processing constitutes the key pathological feature of these disorders. The current review focuses on protein truncation as a common denominator of neurodegenerative foldopathies, which is considered to be the major driving force behind the pathological metamorphosis of brain IDPs. The aim of the review is to emphasize the key role of the protein truncation in the pathogenic pathways of neurodegenerative diseases. A deeper understanding of the complex downstream processing of the IDPs, resulting in the generation of pathologically modified proteins might be a prerequisite for the successful therapeutic strategies of several fatal neurodegenerative diseases.
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Affiliation(s)
- Santosh Jadhav
- Institute of Neuroimmunology, Slovak Academy of Sciences, Centre of Excellence for Alzheimer's Disease and Related Disorders, Dubravska cesta 9, 845 10, Bratislava, Slovak Republic
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Beyer K, Ariza A. Alpha-Synuclein Posttranslational Modification and Alternative Splicing as a Trigger for Neurodegeneration. Mol Neurobiol 2012; 47:509-24. [DOI: 10.1007/s12035-012-8330-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 08/13/2012] [Indexed: 12/11/2022]
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69
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Choi HS, Liew H, Jang A, Kim YM, Lashuel H, Suh YH. Phosphorylation of α-synuclein is crucial in compensating for proteasomal dysfunction. Biochem Biophys Res Commun 2012; 424:597-603. [DOI: 10.1016/j.bbrc.2012.06.159] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 06/30/2012] [Indexed: 12/13/2022]
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Nakamura T, Cho DH, Lipton SA. Redox regulation of protein misfolding, mitochondrial dysfunction, synaptic damage, and cell death in neurodegenerative diseases. Exp Neurol 2012; 238:12-21. [PMID: 22771760 DOI: 10.1016/j.expneurol.2012.06.032] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 06/20/2012] [Accepted: 06/27/2012] [Indexed: 12/21/2022]
Abstract
The loss or injury of neurons associated with oxidative and nitrosative redox stress plays an important role in the onset of various neurodegenerative diseases. Specifically, nitric oxide (NO), can affect neuronal survival through a process called S-nitrosylation, by which the NO group undergoes a redox reaction with specific protein thiols. This in turn can lead to the accumulation of misfolded proteins, which generally form aggregates in Alzheimer's, Parkinson's, and other neurodegenerative diseases. Evidence suggests that S-nitrosylation can also impair mitochondrial function and lead to excessive fission of mitochondria and consequent bioenergetic compromise via effects on the activity of the fission protein dynamin-related protein 1 (Drp1). This insult leads to synaptic dysfunction and loss. Additionally, high levels of NO can S-nitrosylate a number of aberrant targets involved in neuronal survival pathways, including the antiapoptotic protein XIAP, inhibiting its ability to prevent apoptosis.
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Affiliation(s)
- Tomohiro Nakamura
- Del E. Webb Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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71
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Doorn KJ, Lucassen PJ, Boddeke HW, Prins M, Berendse HW, Drukarch B, van Dam AM. Emerging roles of microglial activation and non-motor symptoms in Parkinson's disease. Prog Neurobiol 2012; 98:222-38. [PMID: 22732265 DOI: 10.1016/j.pneurobio.2012.06.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 06/15/2012] [Indexed: 10/28/2022]
Abstract
Recent data has indicated that the traditional view of Parkinson's disease (PD) as an isolated disorder of the nigrostriatal dopaminergic system alone is an oversimplification of its complex symptomatology. Aside from classical motor deficits, various non-motor symptoms including autonomic dysfunction, sensory and cognitive impairments as well as neuropsychiatric alterations and sleep disturbances are common in PD. Some of these non-motor symptoms can even antedate the motor problems. Many of them are associated with extranigral neuropathological changes, such as extensive α-synuclein pathology and also neuroinflammatory responses in specific brain regions, i.e. microglial activation, which has been implicated in several aspects of PD pathogenesis and progression. However, microglia do not represent a uniform population, but comprise a diverse group of cells with brain region-specific phenotypes that can exert beneficial or detrimental effects, depending on the local phenotype and context. Understanding how microglia can be neuroprotective in one brain region, while promoting neurotoxicity in another, will improve our understanding of the role of microglia in neurodegeneration in general, and of their role in PD pathology in particular. Since neuroinflammatory responses are in principle modifiable, such approaches could help to identify new targets or adjunctive therapies for the full spectrum of PD-related symptoms.
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Affiliation(s)
- Karlijn J Doorn
- University of Amsterdam, Swammerdam Institute for Life Sciences, Center for Neuroscience, Amsterdam, The Netherlands
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72
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αSynuclein and Mitochondrial Dysfunction: A Pathogenic Partnership in Parkinson's Disease? PARKINSONS DISEASE 2012; 2012:829207. [PMID: 22737587 PMCID: PMC3377350 DOI: 10.1155/2012/829207] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 03/14/2012] [Indexed: 11/17/2022]
Abstract
Parkinson's Disease (PD) is a complex, chronic, progressive, and debilitating neurodegenerative disorder. Neither a cure nor effective long-term therapy exist and the lack of knowledge of the molecular mechanisms responsible for PD development is a major impediment to therapeutic advances. The protein αSynuclein is a central component in PD pathogenesis yet its cellular targets and mechanism of toxicity remains unknown. Mitochondrial dysfunction is also a common theme in PD patients and this review explores the strong possibility that αSynuclein and mitochondrial dysfunction have an inter-relationship responsible for underlying the disease pathology. Amplifying cycles of mitochondrial dysfunction and αSynuclein toxicity can be envisaged, with either being the disease-initiating factor yet acting together during disease progression. Multiple potential mechanisms exist in which mitochondrial dysfunction and αSynuclein could interact to exacerbate their neurodegenerative properties. Candidates discussed within this review include autophagy, mitophagy, mitochondrial dynamics/fusion/fission, oxidative stress and reactive oxygen species, endoplasmic reticulum stress, calcium, nitrosative stress and αSynuclein Oligomerization.
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Hung LW, Villemagne VL, Cheng L, Sherratt NA, Ayton S, White AR, Crouch PJ, Lim S, Leong SL, Wilkins S, George J, Roberts BR, Pham CLL, Liu X, Chiu FCK, Shackleford DM, Powell AK, Masters CL, Bush AI, O'Keefe G, Culvenor JG, Cappai R, Cherny RA, Donnelly PS, Hill AF, Finkelstein DI, Barnham KJ. The hypoxia imaging agent CuII(atsm) is neuroprotective and improves motor and cognitive functions in multiple animal models of Parkinson's disease. ACTA ACUST UNITED AC 2012; 209:837-54. [PMID: 22473957 PMCID: PMC3328361 DOI: 10.1084/jem.20112285] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The PET imaging agent CuII(atsm) improves motor and cognitive function in Parkinson’s disease. Parkinson’s disease (PD) is a progressive, chronic disease characterized by dyskinesia, rigidity, instability, and tremors. The disease is defined by the presence of Lewy bodies, which primarily consist of aggregated α-synuclein protein, and is accompanied by the loss of monoaminergic neurons. Current therapeutic strategies only give symptomatic relief of motor impairment and do not address the underlying neurodegeneration. Hence, we have identified CuII(atsm) as a potential therapeutic for PD. Drug administration to four different animal models of PD resulted in improved motor and cognition function, rescued nigral cell loss, and improved dopamine metabolism. In vitro, this compound is able to inhibit the effects of peroxynitrite-driven toxicity, including the formation of nitrated α-synuclein oligomers. Our results show that CuII(atsm) is effective in reversing parkinsonian defects in animal models and has the potential to be a successful treatment of PD.
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Affiliation(s)
- Lin W Hung
- The Mental Health Research Institute, the University of Melbourne, Victoria 3010 Australia
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74
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Nunes AF, Amaral JD, Lo AC, Fonseca MB, Viana RJS, Callaerts-Vegh Z, D'Hooge R, Rodrigues CMP. TUDCA, a bile acid, attenuates amyloid precursor protein processing and amyloid-β deposition in APP/PS1 mice. Mol Neurobiol 2012; 45:440-54. [PMID: 22438081 DOI: 10.1007/s12035-012-8256-y] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 03/01/2012] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by accumulation of amyloid-β (Aβ) peptide in the hippocampus and frontal cortex of the brain, leading to progressive cognitive decline. The endogenous bile acid tauroursodeoxycholic acid (TUDCA) is a strong neuroprotective agent in several experimental models of disease, including neuronal exposure to Aβ. Nevertheless, the therapeutic role of TUDCA in AD pathology has not yet been ascertained. Here we report that feeding APP/PS1 double-transgenic mice with diet containing 0.4 % TUDCA for 6 months reduced accumulation of Aβ deposits in the brain, markedly ameliorating memory deficits. This was accompanied by reduced glial activation and neuronal integrity loss in TUDCA-fed APP/PS1 mice compared to untreated APP/PS1 mice. Furthermore, TUDCA regulated lipid-metabolism mediators involved in Aβ production and accumulation in the brains of transgenic mice. Overall amyloidogenic APP processing was reduced with TUDCA treatment, in association with, but not limited to, modulation of γ-secretase activity. Consequently, a significant decrease in Aβ(1-40) and Aβ(1-42) levels was observed in both hippocampus and frontal cortex of TUDCA-treated APP/PS1 mice, suggesting that chronic feeding of TUDCA interferes with Aβ production, possibly through the regulation of lipid-metabolism mediators associated with APP processing. These results highlight TUDCA as a potential therapeutic strategy for the prevention and treatment of AD.
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Affiliation(s)
- Ana F Nunes
- Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, 1649-003, Portugal
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Rochet JC, Hay BA, Guo M. Molecular insights into Parkinson's disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:125-88. [PMID: 22482450 DOI: 10.1016/b978-0-12-385883-2.00011-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mutations in SNCA, PINK1, parkin, and DJ-1 are associated with autosomal-dominant or autosomal-recessive forms of Parkinson's disease (PD), the second most common neurodegenerative disorder. Studies on the structural and functional properties of the corresponding gene products have provided significant insights into the molecular underpinnings of familial PD and the much more common sporadic forms of the disease. Here, we review recent advances in our understanding of four PD-related gene products: α-synuclein, parkin, PINK1, and DJ-1. In Part 1, we review new insights into the role of α-synuclein in PD. In Part 2, we summarize the latest developments in understanding the role of mitochondrial dysfunction in PD, emphasizing the role of the PINK1/parkin pathway in regulating mitochondrial dynamics and mitophagy. The role of DJ-1 is also discussed. In Part 3, we point out converging pathways and future directions.
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Affiliation(s)
- Jean-Christophe Rochet
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, USA
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76
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Breydo L, Wu JW, Uversky VN. Α-synuclein misfolding and Parkinson's disease. Biochim Biophys Acta Mol Basis Dis 2011; 1822:261-85. [PMID: 22024360 DOI: 10.1016/j.bbadis.2011.10.002] [Citation(s) in RCA: 447] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/26/2011] [Accepted: 10/03/2011] [Indexed: 12/21/2022]
Abstract
Substantial evidence links α-synuclein, a small highly conserved presynaptic protein with unknown function, to both familial and sporadic Parkinson's disease (PD). α-Synuclein has been identified as the major component of Lewy bodies and Lewy neurites, the characteristic proteinaceous deposits that are the hallmarks of PD. α-Synuclein is a typical intrinsically disordered protein, but can adopt a number of different conformational states depending on conditions and cofactors. These include the helical membrane-bound form, a partially-folded state that is a key intermediate in aggregation and fibrillation, various oligomeric species, and fibrillar and amorphous aggregates. The molecular basis of PD appears to be tightly coupled to the aggregation of α-synuclein and the factors that affect its conformation. This review examines the different aggregation states of α-synuclein, the molecular mechanism of its aggregation, and the influence of environmental and genetic factors on this process.
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Affiliation(s)
- Leonid Breydo
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612, USA
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Elcoroaristizabal Martín X, Gómez Busto F, González Fernández MC, de Pancorbo MM. [Role of genetics in the etiology of synucleinopathies]. Rev Esp Geriatr Gerontol 2011; 46 Suppl 1:3-11. [PMID: 22152908 DOI: 10.1016/j.regg.2011.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The protein family known as synucleins is composed of α-, β- and γ-synuclein. The most widely studied is the α-synuclein protein due to its participation in essential processes of the central nervous system. Neurotoxicity of this protein is related to the presence of multiplications (duplications and triplications) and point mutations in the gene sequence of the α-synuclein gene (SNCA), differential expression of its isoforms and variations in post-transductional modifications. Neurotoxicity is also related to cytoplasmic inclusions known as Lewy bodies (LBs) and Lewy neurites (LNs), which are also present in α-synucleinopathies. In general, the β-synuclein protein, codified by the SNCB gene, acts as a regulator of processes triggered by α-synuclein and its function is altered by variations in the gene sequence, while γ-synuclein, codified by the SNCG gene, seems to play a major role in certain tumoral processes.
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Affiliation(s)
- Xabier Elcoroaristizabal Martín
- Grupo de Investigación BIOMICS, Departamento de Biología Celular A, Centro de Investigación y Estudios Avanzados Lucio Lascaray, Universidad del País Vasco UPV/EHU, Vitoria-Gasteiz, España
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Joshi RL, Torero Ibad R, Rheey J, Castagner F, Prochiantz A, Moya KL. Cell non-autonomous functions of homeoproteins in neuroprotection in the brain. FEBS Lett 2011; 585:1573-8. [PMID: 21565195 DOI: 10.1016/j.febslet.2011.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 04/29/2011] [Accepted: 05/01/2011] [Indexed: 12/19/2022]
Abstract
Homeoproteins transcription factors can transfer between cells and play important roles in development. However, some of these homeoproteins are expressed in the adult, but their function is unknown. The loss of mesencephalic dopaminergic (mDA) neurons is the cause of Parkinson's disease. In mice lacking a functional allele for the Engrailed 1 homeoprotein, mDA neurons progressively die starting about 6 weeks after birth. Infusion of recombinant Engrailed stops the death of these neurons demonstrating that homeoproteins can be neuroprotective. This has been extended to retinal ganglion cell neurons (RGCs), which die in glaucoma and optic neuropathies. The homeoprotein Otx2 promotes the survival of injured adult RGCs both in vitro and in vivo. These examples raise the possibility that homeoproteins may provide neuroprotection to neurons vulnerable in other neurodegenerative diseases.
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Affiliation(s)
- Rajiv L Joshi
- Development and Neuropharmacology Group, Centre for Interdisciplinary Research in Biology (CIRB), CNRS UMR 7241, INSERM U 1050, Collège de France, Paris, France.
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Sevcsik E, Trexler AJ, Dunn JM, Rhoades E. Allostery in a disordered protein: oxidative modifications to α-synuclein act distally to regulate membrane binding. J Am Chem Soc 2011; 133:7152-8. [PMID: 21491910 DOI: 10.1021/ja2009554] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Both oxidative stress and aggregation of the protein α-synuclein (aS) have been implicated as key factors in the etiology of Parkinson's disease. Specifically, oxidative modifications to aS disrupt its binding to lipid membranes, an interaction considered critical to its native function. Here we seek to provide a mechanistic explanation for this phenomenon by investigating the effects of oxidative nitration of tyrosine residues on the structure of aS and its interaction with lipid membranes. Membrane binding is mediated by the first ∼95 residues of aS. We find that nitration of the single tyrosine (Y39) in this domain disrupts binding due to electrostatic repulsion. Moreover, we observe that nitration of the three tyrosines (Y125/133/136) in the C-terminal domain is equally effective in perturbing binding, an intriguing result given that the C-terminus is not thought to interact directly with the lipid bilayer. Our investigations show that tyrosine nitration results in a change of the conformational states populated by aS in solution, with the most prominent changes occurring in the C-terminal region. These results lead us to suggest that nitration of Y125/133/136 reduces the membrane-binding affinity of aS through allosteric coupling by altering the ensemble of conformational states and depopulating those capable of membrane binding. While allostery is a well-established concept for structured proteins, it has only recently been discussed in the context of disordered proteins. We propose that allosteric regulation through modification of specific residues in, or ligand binding to, the C-terminus may even be a general mechanism for modulating aS function.
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Affiliation(s)
- Eva Sevcsik
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, USA
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