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Aubrey LD, Ninkina N, Ulamec SM, Abramycheva NY, Vasili E, Devine OM, Wilkinson M, Mackinnon E, Limorenko G, Walko M, Muwanga S, Amadio L, Peters OM, Illarioshkin SN, Outeiro TF, Ranson NA, Brockwell DJ, Buchman VL, Radford SE. Substitution of Met-38 to Ile in γ-synuclein found in two patients with amyotrophic lateral sclerosis induces aggregation into amyloid. Proc Natl Acad Sci U S A 2024; 121:e2309700120. [PMID: 38170745 PMCID: PMC10786281 DOI: 10.1073/pnas.2309700120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 11/17/2023] [Indexed: 01/05/2024] Open
Abstract
α-, β-, and γ-Synuclein are intrinsically disordered proteins implicated in physiological processes in the nervous system of vertebrates. α-synuclein (αSyn) is the amyloidogenic protein associated with Parkinson's disease and certain other neurodegenerative disorders. Intensive research has focused on the mechanisms that cause αSyn to form amyloid structures, identifying its NAC region as being necessary and sufficient for amyloid assembly. Recent work has shown that a 7-residue sequence (P1) is necessary for αSyn amyloid formation. Although γ-synuclein (γSyn) is 55% identical in sequence to αSyn and its pathological deposits are also observed in association with neurodegenerative conditions, γSyn is resilient to amyloid formation in vitro. Here, we report a rare single nucleotide polymorphism (SNP) in the SNCG gene encoding γSyn, found in two patients with amyotrophic lateral sclerosis (ALS). The SNP results in the substitution of Met38 with Ile in the P1 region of the protein. These individuals also had a second, common and nonpathological, SNP in SNCG resulting in the substitution of Glu110 with Val. In vitro studies demonstrate that the Ile38 variant accelerates amyloid fibril assembly. Contrastingly, Val110 retards fibril assembly and mitigates the effect of Ile38. Substitution of residue 38 with Leu had little effect, while Val retards, and Ala increases the rate of amyloid formation. Ile38 γSyn also results in the formation of γSyn-containing inclusions in cells. The results show how a single point substitution can enhance amyloid formation of γSyn and highlight the P1 region in driving amyloid formation in another synuclein family member.
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Affiliation(s)
- Liam D. Aubrey
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Natalia Ninkina
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
- Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University, Belgorod308015, Russian Federation
| | - Sabine M. Ulamec
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Natalia Y. Abramycheva
- Laboratory of Neurobiology and Tissue Engineering, Brain Science Institute, Research Center of Neurology, Moscow125367, Russia
| | - Eftychia Vasili
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - Oliver M. Devine
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Martin Wilkinson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Eilish Mackinnon
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
| | - Galina Limorenko
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, LausanneCH-1015, Switzerland
| | - Martin Walko
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, School of Chemistry, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Sarah Muwanga
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
| | - Leonardo Amadio
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
| | - Owen M. Peters
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
| | - Sergey N. Illarioshkin
- Laboratory of Neurobiology and Tissue Engineering, Brain Science Institute, Research Center of Neurology, Moscow125367, Russia
| | - Tiago F. Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen37075, Germany
- Max Planck Institute for Multidisciplinary Sciences, Goettingen37075, Germany
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon TyneNE2 4HH, United Kingdom
- Scientific employee with a honorary contract at Deutsches Zentrum für Neurodegenerative Erkrankungen, Göttingen37075, Germany
| | - Neil A. Ranson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - David J. Brockwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Vladimir L. Buchman
- School of Biosciences, Cardiff University, CardiffCF10 3AX, United Kingdom
- Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University, Belgorod308015, Russian Federation
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Science, University of Leeds, LeedsLS2 9JT, United Kingdom
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Zanotti LC, Malizia F, Cesatti Laluce N, Avila A, Mamberto M, Anselmino LE, Menacho-Márquez M. Synuclein Proteins in Cancer Development and Progression. Biomolecules 2023; 13:980. [PMID: 37371560 PMCID: PMC10296229 DOI: 10.3390/biom13060980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023] Open
Abstract
Synucleins are a family of small, soluble proteins mainly expressed in neural tissue and in certain tumors. Since their discovery, tens of thousands of scientific reports have been published about this family of proteins as they are associated with severe human diseases. Although the physiological function of these proteins is still elusive, their relationship with neurodegeneration and cancer has been clearly described over the years. In this review, we summarize data connecting synucleins and cancer, going from the structural description of these molecules to their involvement in tumor-related processes, and discuss the putative use of these proteins as cancer molecular biomarkers.
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Affiliation(s)
- Lucía C. Zanotti
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER, CONICET-UNR), Facultad de Ciencias Médicas (UNR), Rosario 3100, Argentina
- Instituto de Inmunología Clínica y Experimental, CONICET, Rosario 3100, Argentina
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
| | - Florencia Malizia
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER, CONICET-UNR), Facultad de Ciencias Médicas (UNR), Rosario 3100, Argentina
- Instituto de Inmunología Clínica y Experimental, CONICET, Rosario 3100, Argentina
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
| | - Nahuel Cesatti Laluce
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER, CONICET-UNR), Facultad de Ciencias Médicas (UNR), Rosario 3100, Argentina
- Instituto de Inmunología Clínica y Experimental, CONICET, Rosario 3100, Argentina
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
| | - Aylén Avila
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
| | - Macarena Mamberto
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER, CONICET-UNR), Facultad de Ciencias Médicas (UNR), Rosario 3100, Argentina
- Instituto de Inmunología Clínica y Experimental, CONICET, Rosario 3100, Argentina
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
| | - Luciano E. Anselmino
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER, CONICET-UNR), Facultad de Ciencias Médicas (UNR), Rosario 3100, Argentina
- Instituto de Inmunología Clínica y Experimental, CONICET, Rosario 3100, Argentina
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
| | - Mauricio Menacho-Márquez
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER, CONICET-UNR), Facultad de Ciencias Médicas (UNR), Rosario 3100, Argentina
- Instituto de Inmunología Clínica y Experimental, CONICET, Rosario 3100, Argentina
- Centro de Investigación y Producción de Reactivos Biológicos (CIPReB), Facultad de Ciencias Médicas (UNR), Suipacha 660, Rosario 2000, Argentina
- Centro de Investigación del Cáncer de Rosario, Red de Investigación del Cáncer de Rosario (RICaR), 37007 Salamanca, Spain
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Scarlata S. The role of phospholipase Cβ on the plasma membrane and in the cytosol: How modular domains enable novel functions. Adv Biol Regul 2019; 73:100636. [PMID: 31409535 DOI: 10.1016/j.jbior.2019.100636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 07/14/2019] [Accepted: 07/25/2019] [Indexed: 01/14/2023]
Abstract
Phospholipase Cβ (PLCβ) is a signaling enzyme activated by G proteins to generate calcium signals. The catalytic core of PLCβ is surrounded by modular domains that mediate the interaction of the enzyme with known protein partners on the plasma membrane. The C-terminal region PLCβ contains a novel coiled-coil domain that is required for Gαq binding and activation. Recent work has shown that this domain also binds a number of cytosolic proteins that regulate protein translation, and that these proteins compete with Gαq for PLCβ binding. The ability of PLCβ to shuttle between the cytosol to impact protein translation and the plasma membrane to mediate calcium signals puts PLCβ in a central role in cell function.
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Affiliation(s)
- Suzanne Scarlata
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA, 01609, United States.
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γ-Synuclein Induces Human Cortical Astrocyte Proliferation and Subsequent BDNF Expression and Release. Neuroscience 2019; 410:41-54. [PMID: 31078687 DOI: 10.1016/j.neuroscience.2019.04.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 01/03/2023]
Abstract
γ-Synuclein (γ-syn) is expressed by astrocytes in the human nervous system, and increased extracellularly in the brain and cerebrospinal fluid of individuals diagnosed with Alzheimer's disease. Upregulation of γ-syn also coincides with proliferation of glioblastomas and other cancers. In order to better understand regulation and function of extracellular γ-syn, primary human cortical astrocytes were treated with γ-syn conditioned media at various physiological concentrations (50, 100, 150 nM) after cell synchronization. Additionally, extracellular brain-derived neurotrophic factor (BDNF), a neuroprotective growth factor released by astrocytes that has been shown to be decreased extracellularly in neurodegenerative disease, was observed in response to γ-syn treatment. Analysis of 5-bromodeoxyuridine (BrdU) and propidium iodide through flow cytometry 24 h after release from synchronization revealed an increase in G2/M phase of the cell cycle with 100 nM γ-syn during initial cell division, an effect that was reversed at 48 h. However, increased extracellular BDNF was observed at 48 h with 100 nM and 150 nM γ-syn treatment with no difference between controls at 24 h. Further analysis of cell cycle markers with immunocytochemistry of BrdU and Ki67 after treatment with 100 nM γ-syn confirmed increased initial cell proliferation and decreased non-proliferating cells. Western blot analysis demonstrated increased γ-syn levels after 100 nM treatment at 24 and 48 h, and increased pro-BDNF, mature BDNF and cell viability at 48 h. The results demonstrate that γ-syn internalization by human cortical astrocytes causes upregulation of the cell cycle, followed by subsequent BDNF expression and release.
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Roy S, Bhat R. Suppression, disaggregation, and modulation of γ-Synuclein fibrillation pathway by green tea polyphenol EGCG. Protein Sci 2018; 28:382-402. [PMID: 30394624 DOI: 10.1002/pro.3549] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/31/2018] [Indexed: 12/24/2022]
Abstract
Oligomerization of γ-Synuclein is known to have implications for both neurodegeneration and cancer. Although it is known to co-exist with the fibrillar deposits of α-Synuclein (Lewy bodies), a hallmark in Parkinson's disease (PD), the effect of potential therapeutic modulators on the fibrillation pathway of γ-Syn remains unexplored. By a combined use of various biophysical tools and cytotoxicity assays we demonstrate that the flavonoid epigallocatechin-3-gallate (EGCG) significantly suppresses γ-Syn fibrillation by affecting its nucleation and binds with the unstructured, nucleus forming oligomers of γ-Syn to modulate the pathway to form α-helical containing higher-order oligomers (~158 kDa and ~ 670 kDa) that are SDS-resistant and conformationally restrained in nature. Seeding studies reveal that these oligomers although "on-pathway" in nature, are kinetically retarded and rate-limiting species that slows down fibril elongation. We observe that EGCG also disaggregates the protofibrils and mature γ-Syn fibrils into similar SDS-resistant oligomers. Steady-state and time-resolved fluorescence spectroscopy and isothermal titration calorimetry (ITC) reveal a weak non-covalent interaction between EGCG and γ-Syn with the dissociation constant in the mM range (Kd ~ 2-10 mM). Interestingly, while EGCG-generated oligomers completely rescue the breast cancer (MCF-7) cells from γ-Syn toxicity, it reduces the viability of neuroblastoma (SH-SY5Y) cells. However, the disaggregated oligomers of γ-Syn are more toxic than the disaggregated fibrils for MCF-7cells. These findings throw light on EGCG-mediated modulation of γ-Syn fibrillation and suggest that investigation on the effects of such modulators on γ-Syn fibrillation is critical in identifying effective therapeutic strategies using small molecule modulators of synucleopathies.
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Affiliation(s)
- Sneha Roy
- Biophysical Chemistry Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Mehrauli Road, New Delhi, 110067, India
| | - Rajiv Bhat
- Biophysical Chemistry Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Mehrauli Road, New Delhi, 110067, India
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DeForte S, Reddy KD, Uversky VN. Quarterly intrinsic disorder digest (January-February-March, 2014). INTRINSICALLY DISORDERED PROTEINS 2016; 4:e1153395. [PMID: 28232896 DOI: 10.1080/21690707.2016.1153395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This is the 5th issue of the Digested Disorder series that represents a reader's digest of the scientific literature on intrinsically disordered proteins. We continue to use only 2 criteria for inclusion of a paper to this digest: The publication date (a paper should be published within the covered time frame) and the topic (a paper should be dedicated to any aspect of protein intrinsic disorder). The current digest issue covers papers published during the first quarter of 2014; i.e., during the period of January, February, and March of 2014. Similar to previous issues, the papers are grouped hierarchically by topics they cover, and for each of the included papers a short description is given on its major findings.
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Affiliation(s)
- Shelly DeForte
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida , Tampa, FL, USA
| | - Krishna D Reddy
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida , Tampa, FL, USA
| | - Vladimir N Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; Biology Department, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia; Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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Golebiewska U, Scarlata S. High pressure promotes alpha-synuclein aggregation in cultured neuronal cells. FEBS Lett 2015; 589:3309-12. [PMID: 26434717 DOI: 10.1016/j.febslet.2015.09.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/06/2015] [Accepted: 09/15/2015] [Indexed: 12/26/2022]
Abstract
α-Synuclein is found in plaques associated with Parkinson's and other neurodegenerative diseases. Changes in α-synuclein oligomerization are thought to give rise to nucleation of neurodegenerative plaques. Here, we investigated the effect of hydrostatic pressure on the aggregation of α-synuclein in cultured neuronal cells. We found that hydrostatic pressure is associated with a transition from monomeric to higher order α-synuclein aggregates. We then tested whether this aggregation is associated with the loss of binding partners, such as phospholipase Cβ. We found that increased pressure reduces the level of PLCβ1 and the amount of α-synuclein/PLCβ1 complexes. These studies suggest that pressure promotes release of α-synuclein from protein partners promoting its oligomerization.
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Affiliation(s)
- Urszula Golebiewska
- Dept. of Biological Sciences and Geology, Queensborough Community College, Bayside, NY 11364, USA
| | - Suzanne Scarlata
- Dept. of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA 01609 USA.
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New insights into cellular α-synuclein homeostasis in health and disease. Curr Opin Neurobiol 2015; 36:15-22. [PMID: 26282834 DOI: 10.1016/j.conb.2015.07.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 07/24/2015] [Indexed: 12/15/2022]
Abstract
α-Synuclein (αSyn) is a highly abundant neuronal protein whose exact structure and function are under debate. Misfolding and aggregation of this normally soluble, 140-residue polypeptide underlies a group of neurodegenerative disorders called synucleinopathies, including Parkinson's disease (PD) and dementia with Lewy bodies (DLB). The αSyn field has focused increasing attention on the hypotheses that certain aggregates of αSyn may be directly toxic to the neurons in which they arise and/or that aggregates can be released from some neurons and diffuse by undefined mechanisms to other neurons to seed αSyn in the recipient cells, thus propagating neuropathology by a non-cell autonomous process ('pathogenic spread'). While intense interest in these hypotheses has led to new approaches and tools to model aspects of the disorders, it is important to analyze which molecular events initiate αSyn aggregation inside neurons in the first place. Here, we review new insights into how neuronal αSyn homeostasis may be maintained under physiological conditions but perturbed by pathological factors.
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KTKEGV repeat motifs are key mediators of normal α-synuclein tetramerization: Their mutation causes excess monomers and neurotoxicity. Proc Natl Acad Sci U S A 2015; 112:9596-601. [PMID: 26153422 DOI: 10.1073/pnas.1505953112] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
α-Synuclein (αS) is a highly abundant neuronal protein that aggregates into β-sheet-rich inclusions in Parkinson's disease (PD). αS was long thought to occur as a natively unfolded monomer, but recent work suggests it also occurs normally in α-helix-rich tetramers and related multimers. To elucidate the fundamental relationship between αS multimers and monomers in living neurons, we performed systematic mutagenesis to abolish self-interactions and learn which structural determinants underlie native multimerization. Unexpectedly, tetramers/multimers still formed in cells expressing each of 14 sequential 10-residue deletions across the 140-residue polypeptide. We postulated compensatory effects among the six highly conserved and one to three additional αS repeat motifs (consensus: KTKEGV), consistent with αS and its homologs β- and γ-synuclein all forming tetramers while sharing only the repeats. Upon inserting in-register missense mutations into six or more αS repeats, certain mutations abolished tetramer formation, shown by intact-cell cross-linking and independently by fluorescent-protein complementation. For example, altered repeat motifs KLKEGV, KTKKGV, KTKEIV, or KTKEGW did not support tetramerization, indicating the importance of charged or small residues. When we expressed numerous different in-register repeat mutants in human neural cells, all multimer-abolishing but no multimer-neutral mutants caused frank neurotoxicity akin to the proapoptotic protein Bax. The multimer-abolishing variants became enriched in buffer-insoluble cell fractions and formed round cytoplasmic inclusions in primary cortical neurons. We conclude that the αS repeat motifs mediate physiological tetramerization, and perturbing them causes PD-like neurotoxicity. Moreover, the mutants we describe are valuable tools for studying normal and pathological properties of αS and screening for tetramer-stabilizing therapeutics.
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Parkinson-causing α-synuclein missense mutations shift native tetramers to monomers as a mechanism for disease initiation. Nat Commun 2015; 6:7314. [PMID: 26076669 PMCID: PMC4490410 DOI: 10.1038/ncomms8314] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/27/2015] [Indexed: 12/20/2022] Open
Abstract
β-Sheet-rich α-synuclein (αS) aggregates characterize Parkinson's disease (PD). αS was long believed to be a natively unfolded monomer, but recent work suggests it also occurs in α-helix-rich tetramers. Crosslinking traps principally tetrameric αS in intact normal neurons, but not after cell lysis, suggesting a dynamic equilibrium. Here we show that freshly biopsied normal human brain contains abundant αS tetramers. The PD-causing mutation A53T decreases tetramers in mouse brain. Neurons derived from an A53T patient have decreased tetramers. Neurons expressing E46K do also, and adding 1-2 E46K-like mutations into the canonical αS repeat motifs (KTKEGV) further reduces tetramers, decreases αS solubility and induces neurotoxicity and round inclusions. The other three fPD missense mutations likewise decrease tetramer:monomer ratios. The destabilization of physiological tetramers by PD-causing missense mutations and the neurotoxicity and inclusions induced by markedly decreasing tetramers suggest that decreased α-helical tetramers and increased unfolded monomers initiate pathogenesis. Tetramer-stabilizing compounds should prevent this.
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