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Wallace JN, Crockford ZC, Román-Vendrell C, Brady EB, Hoffmann C, Vargas KJ, Potcoava M, Wegman ME, Alford ST, Milovanovic D, Morgan JR. Excess phosphoserine-129 α-synuclein induces synaptic vesicle trafficking and declustering defects at a vertebrate synapse. Mol Biol Cell 2024; 35:ar10. [PMID: 37991902 PMCID: PMC10881165 DOI: 10.1091/mbc.e23-07-0269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 11/06/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023] Open
Abstract
α-Synuclein is a presynaptic protein that regulates synaptic vesicle (SV) trafficking. In Parkinson's disease (PD) and dementia with Lewy bodies (DLB), α-synuclein aberrantly accumulates throughout neurons, including at synapses. During neuronal activity, α-synuclein is reversibly phosphorylated at serine 129 (pS129). While pS129 comprises ∼4% of total α-synuclein under physiological conditions, it dramatically increases in PD and DLB brains. The impacts of excess pS129 on synaptic function are currently unknown. We show here that compared with wild-type (WT) α-synuclein, pS129 exhibits increased binding and oligomerization on synaptic membranes and enhanced vesicle "microclustering" in vitro. Moreover, when acutely injected into lamprey reticulospinal axons, excess pS129 α-synuclein robustly localized to synapses and disrupted SV trafficking in an activity-dependent manner, as assessed by ultrastructural analysis. Specifically, pS129 caused a declustering and dispersion of SVs away from the synaptic vicinity, leading to a significant loss of total synaptic membrane. Live imaging further revealed altered SV cycling, as well as microclusters of recently endocytosed SVs moving away from synapses. Thus, excess pS129 caused an activity-dependent inhibition of SV trafficking via altered vesicle clustering/reclustering. This work suggests that accumulation of pS129 at synapses in diseases like PD and DLB could have profound effects on SV dynamics.
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Affiliation(s)
| | | | | | - Emily B. Brady
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, and
| | - Christian Hoffmann
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Karina J. Vargas
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, and
- Department of Cell Biology, University of Pittsburgh, PA 15261
| | - Mariana Potcoava
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612
| | | | - Simon T. Alford
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612
| | - Dragomir Milovanovic
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
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2
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Lomeli-Lepe AK, Castañeda-Cabral JL, López-Pérez SJ. Synucleinopathies: Intrinsic and Extrinsic Factors. Cell Biochem Biophys 2023; 81:427-442. [PMID: 37526884 DOI: 10.1007/s12013-023-01154-z] [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: 05/05/2023] [Accepted: 07/23/2023] [Indexed: 08/02/2023]
Abstract
α-Synucleinopathies are a group of neurodegenerative disorders characterized by alterations in α-synuclein (α-syn), a protein associated with membrane phospholipids, whose precise function in normal cells is still unknown. These kinds of diseases are caused by multiple factors, but the regulation of the α-syn gene is believed to play a central role in the pathology of these disorders; therefore, the α-syn gene is one of the most studied genes. α-Synucleinopathies are complex disorders that derive from the interaction between genetic and environmental factors. Here, we offer an update on the landscape of the epigenetic regulation of α-syn gene expression that has been linked with α-synucleinopathies. We also delve into the reciprocal influence between epigenetic modifications and other factors related to these disorders, such as posttranslational modifications, microbiota participation, interactions with lipids, neuroinflammation and oxidative stress, to promote α-syn aggregation by acting on the transcription and/or translation of the α-syn gene.
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Affiliation(s)
- Alma Karen Lomeli-Lepe
- Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Guadalajara, JAL, México
| | - Jose Luis Castañeda-Cabral
- Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Guadalajara, JAL, México
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3
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Nikom D, Zheng S. Alternative splicing in neurodegenerative disease and the promise of RNA therapies. Nat Rev Neurosci 2023; 24:457-473. [PMID: 37336982 DOI: 10.1038/s41583-023-00717-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2023] [Indexed: 06/21/2023]
Abstract
Alternative splicing generates a myriad of RNA products and protein isoforms of different functions from a single gene. Dysregulated alternative splicing has emerged as a new mechanism broadly implicated in the pathogenesis of neurodegenerative diseases such as Alzheimer disease, amyotrophic lateral sclerosis, frontotemporal dementia, Parkinson disease and repeat expansion diseases. Understanding the mechanisms and functional outcomes of abnormal splicing in neurological disorders is vital in developing effective therapies to treat mis-splicing pathology. In this Review, we discuss emerging research and evidence of the roles of alternative splicing defects in major neurodegenerative diseases and summarize the latest advances in RNA-based therapeutic strategies to target these disorders.
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Affiliation(s)
- David Nikom
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, USA
- Center for RNA Biology and Medicine, University of California, Riverside, Riverside, CA, USA
| | - Sika Zheng
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA, USA.
- Center for RNA Biology and Medicine, University of California, Riverside, Riverside, CA, USA.
- Division of Biomedical Sciences, University of California, Riverside, Riverside, CA, USA.
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4
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Kim M, Bezprozvanny I. Potential direct role of synuclein in dopamine transport and its implications for Parkinson's disease pathogenesis. Biochem Biophys Res Commun 2023; 671:18-25. [PMID: 37290280 DOI: 10.1016/j.bbrc.2023.05.110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/10/2023]
Abstract
Parkinson Disease (PD) is a progressive neurodegenerative disorder that is caused by dysfunction and death of dopaminergic neurons. Mutations in the gene encoding α-synuclein (ASYN) have been linked with familial PD (FPD). Despite important role of ASYN in PD pathology, its normal biological function has not been clarified, although direct action of ASYN in synaptic transmission and dopamine (DA+) release have been proposed. In the present report we propose a novel hypothesis that ASYN functions as DA+/H+ exchanger that can facilitate transport of dopamine across synaptic vesicle (SV) membrane by taking advantage of proton gradient between SV lumen and cytoplasm. According to this hypothesis, normal physiological role of ASYN consists of fine-tuning levels of dopamine in the SVs based on cytosolic concentration of dopamine and intraluminal pH. This hypothesis is based on similarity in domain structure of ASYN and pHILP, a designed peptide developed to mediate loading of lipid nanoparticles with the cargo molecules. We reason that carboxy-terminal acidic loop D2b domain in both ASYN and pHILP binds cargo molecules. By mimicking DA+ association with E/D residues in D2b domain of ASYN using Tyrosine replacement approach (TR) we have been able to estimate that ASYN is able to transfer 8-12 molecules of dopamine across SV membrane on each DA+/H+ exchange cycle. Our results suggest that familial PD mutations (A30P, E46K, H50Q, G51D, A53T and A53E) will interfere with different steps of the exchange cycle, resulting in partial loss of dopamine transport function phenotype. We also predict that similar impairment in ASYN DA+/H+ exchange function also occurs as a result on neuronal aging due to changes in SV lipid composition and size and also dissipation of pH gradient across SV membrane. Proposed novel functional role of ASYN provides novel insights into its biological role and its role in PD pathogenesis.
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Affiliation(s)
- Meewhi Kim
- Dept of Physiology, UT Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Ilya Bezprozvanny
- Dept of Physiology, UT Southwestern Medical Center, Dallas, TX, 75390, USA; Laboratory of Molecular Neurodegeneration, St Petersburg State Polytechnical Universty, St Petersburg, 195251, Russian Federation.
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5
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Tassinari V, La Rosa P, Guida E, Colopi A, Caratelli S, De Paolis F, Gallo A, Cenciarelli C, Sconocchia G, Dolci S, Cesarini V. Contribution of A-to-I RNA editing, M6A RNA Methylation, and Alternative Splicing to physiological brain aging and neurodegenerative diseases. Mech Ageing Dev 2023; 212:111807. [PMID: 37023929 DOI: 10.1016/j.mad.2023.111807] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/31/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023]
Abstract
Aging is a physiological and progressive phenomenon in all organisms' life cycle, characterized by the accumulation of degenerative processes triggered by several alterations within molecular pathways. These changes compromise cell fate, resulting in the loss of functions in tissues throughout the body, including the brain. Physiological brain aging has been linked to structural and functional alterations, as well as to an increased risk of neurodegenerative diseases. Post-transcriptional RNA modifications modulate mRNA coding properties, stability, translatability, expanding the coding capacity of the genome, and are involved in all cellular processes. Among mRNA post-transcriptional modifications, the A-to-I RNA editing, m6A RNA Methylation and Alternative Splicing play a critical role in all the phases of a neuronal cell life cycle and alterations in their mechanisms of action significantly contribute to aging and neurodegeneration. Here we review our current understanding of the contribution of A-to-I RNA editing, m6A RNA Methylation, and Alternative Splicing to physiological brain aging process and neurodegenerative diseases.
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Affiliation(s)
- Valentina Tassinari
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy; Department of Experimental Medicine, University of Rome Tor Vergata, Rome, Italy.
| | - Piergiorgio La Rosa
- Division of Neuroscience, Department of Psychology, Sapienza University of Rome, Rome, Italy; European Center for Brain Research, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Eugenia Guida
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Ambra Colopi
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Sara Caratelli
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Francesca De Paolis
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Angela Gallo
- RNA Editing Lab., Oncohaematology Department, Cellular and Gene Therapy Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Carlo Cenciarelli
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Giuseppe Sconocchia
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy
| | - Susanna Dolci
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - Valeriana Cesarini
- Department of Biomedicine, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Rome, Italy.
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6
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Brady EB, McQuillan M, Medeiros AT, Bubacco L, Sousa R, Lafer EM, Morgan JR. Hsc70 rescues the synaptic vesicle trafficking defects caused by α-synuclein dimers. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000737. [PMID: 36938331 PMCID: PMC10018313 DOI: 10.17912/micropub.biology.000737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/17/2023] [Accepted: 02/23/2023] [Indexed: 03/21/2023]
Abstract
Aberrant buildup of α-synuclein is associated with Parkinson's disease (PD) and other neurodegenerative disorders. At synapses, α-synuclein accumulation leads to severe synaptic vesicle trafficking defects. We previously demonstrated that different molecular species of α-synuclein produce distinct effects on synaptic vesicle recycling, and that the synaptic phenotypes caused by monomeric α-synuclein were ameliorated by Hsc70. Here, we tested whether Hsc70 could also correct synaptic deficits induced by α-synuclein dimers. Indeed, co-injection of Hsc70 with α-synuclein dimers completely reversed the synaptic deficits, resulting in synapses with normal appearance. This work lends additional support for pursuing chaperone-based strategies to treat PD and other synucleinopathies.
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Affiliation(s)
- Emily B. Brady
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts, United States
- Department of Biology, Duke University, Durham, North Carolina, United States
| | - Molly McQuillan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts, United States
- Neuroscience Graduate Program, Brown University, Providence, Rhode Island, United States
| | - Audrey T. Medeiros
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts, United States
- Neuroscience Graduate Program, Brown University, Providence, Rhode Island, United States
| | - Luigi Bubacco
- Department of Biology, University of Padua, Padua, Veneto, Italy
| | - Rui Sousa
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States
| | - Eileen M. Lafer
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States
| | - Jennifer R. Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts, United States
- Correspondence to: Jennifer R. Morgan (
)
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7
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Hassanzadeh K, Morrone C, Akhtari K, Gerhardt E, Zaccagnini L, Outeiro TF, Feligioni M. Non-SUMOylated alternative spliced isoforms of alpha-synuclein are more aggregation-prone and toxic. Mech Ageing Dev 2023; 209:111759. [PMID: 36464085 DOI: 10.1016/j.mad.2022.111759] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 11/14/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022]
Abstract
The exon skipping of α-Synuclein (α-Syn), the main constituent of the abnormal protein aggregation in Lewy bodies of Parkinson's disease (PD), forms four isoforms. In contrast to the full length α-Syn (α-Syn 140), little is known about the splice isoforms' properties and functions. SUMOylation, a post-translational modification, regulates α-Syn function, aggregation, and degradation, but information about α-Syn isoforms and the effect of SUMOylation on them is unknown. Therefore, this study aims to characterize the SUMOylation of α-Syn isoforms and its impact on cell death and α-Syn aggregation. In a cellular model of PD induced by rotenone, cell toxicity, SUMOylation, and α-Syn aggregation with or without isoforms overexpression were evaluated. First, rotenone induced cell toxicity and α-Syn aggregation, with a significant reduction of SUMOylation and autophagy. Boosting SUMOylation prevented α-Syn aggregation, phosphorylation and recovery of autophagy. Moreover, α-Syn 140 and α-Syn 126 were SUMOylated while the other two isoforms, α-Syn 112 and 98 were not and their overexpression showed that were more toxic and induced more α-Syn aggregation. Rotenone increased their toxicity that was not affected by boosting SUMOylation. These results may indicate a role of SUMOylation in modulating α-Syn aggregation, inducing to understanding more about the behavior of α-Syn isoforms.
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Affiliation(s)
| | | | - Keivan Akhtari
- Department of Physics, University of Kurdistan, Sanandaj, Iran
| | - Ellen Gerhardt
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37073 Göttingen, Germany
| | | | - Tiago Fleming Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37073 Göttingen, Germany; Max Planck Institute for Natural Sciences, 37075 Göttingen, Germany; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, NE2 4HH, United Kingdom; Scientific employee with an honorary contract at German Center for Neurodegenerative Diseases (DZNE), 37075 Göttingen, Germany
| | - Marco Feligioni
- EBRI Rita Levi-Montalcini Foundation, Rome 00161, Italy; Department of Neurorehabilitation Sciences, Casa di Cura del Policlinico, Milan 20144, Italy.
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8
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Thapa K, Khan H, Kanojia N, Singh TG, Kaur A, Kaur G. Therapeutic Insights on Ferroptosis in Parkinson's disease. Eur J Pharmacol 2022; 930:175133. [DOI: 10.1016/j.ejphar.2022.175133] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/11/2022] [Accepted: 06/29/2022] [Indexed: 12/27/2022]
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9
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α-Synuclein at the Presynaptic Axon Terminal as a Double-Edged Sword. Biomolecules 2022; 12:biom12040507. [PMID: 35454096 PMCID: PMC9029495 DOI: 10.3390/biom12040507] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 12/12/2022] Open
Abstract
α-synuclein (α-syn) is a presynaptic, lipid-binding protein strongly associated with the neuropathology observed in Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and Alzheimer’s Disease (AD). In normal physiology, α-syn plays a pivotal role in facilitating endocytosis and exocytosis. Interestingly, mutations and modifications of precise α-syn domains interfere with α-syn oligomerization and nucleation that negatively affect presynaptic vesicular dynamics, protein expressions, and mitochondrial profiles. Furthermore, the integration of the α-syn oligomers into the presynaptic membrane results in pore formations, ion influx, and excitotoxicity. Targeted therapies against specific domains of α-syn, including the use of small organic molecules, monoclonal antibodies, and synthetic peptides, are being screened and developed. However, the prospect of an effective α-syn targeted therapy is still plagued by low permeability across the blood–brain barrier (BBB), and poor entry into the presynaptic axon terminals. The present review proposes a modification of current strategies, which includes the use of novel encapsulation technology, such as lipid nanoparticles, to bypass the BBB and deliver such agents into the brain.
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10
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Fouke KE, Wegman ME, Weber SA, Brady EB, Román-Vendrell C, Morgan JR. Synuclein Regulates Synaptic Vesicle Clustering and Docking at a Vertebrate Synapse. Front Cell Dev Biol 2021; 9:774650. [PMID: 34901020 PMCID: PMC8660973 DOI: 10.3389/fcell.2021.774650] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Neurotransmission relies critically on the exocytotic release of neurotransmitters from small synaptic vesicles (SVs) at the active zone. Therefore, it is essential for neurons to maintain an adequate pool of SVs clustered at synapses in order to sustain efficient neurotransmission. It is well established that the phosphoprotein synapsin 1 regulates SV clustering at synapses. Here, we demonstrate that synuclein, another SV-associated protein and synapsin binding partner, also modulates SV clustering at a vertebrate synapse. When acutely introduced to unstimulated lamprey reticulospinal synapses, a pan-synuclein antibody raised against the N-terminal domain of α-synuclein induced a significant loss of SVs at the synapse. Both docked SVs and the distal reserve pool of SVs were depleted, resulting in a loss of total membrane at synapses. In contrast, antibodies against two other abundant SV-associated proteins, synaptic vesicle glycoprotein 2 (SV2) and vesicle-associated membrane protein (VAMP/synaptobrevin), had no effect on the size or distribution of SV clusters. Synuclein perturbation caused a dose-dependent reduction in the number of SVs at synapses. Interestingly, the large SV clusters appeared to disperse into smaller SV clusters, as well as individual SVs. Thus, synuclein regulates clustering of SVs at resting synapses, as well as docking of SVs at the active zone. These findings reveal new roles for synuclein at the synapse and provide critical insights into diseases associated with α-synuclein dysfunction, such as Parkinson’s disease.
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Affiliation(s)
- Kaitlyn E Fouke
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States.,Department of Neurobiology, Duke University, Durham, NC, United States
| | - M Elizabeth Wegman
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Sarah A Weber
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States.,Biological Sciences Collegiate Division, The University of Chicago, Chicago, IL, United States
| | - Emily B Brady
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Cristina Román-Vendrell
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
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11
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Alpha-Synuclein and Cognitive Decline in Parkinson Disease. Life (Basel) 2021; 11:life11111239. [PMID: 34833115 PMCID: PMC8625417 DOI: 10.3390/life11111239] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/08/2021] [Accepted: 11/12/2021] [Indexed: 12/15/2022] Open
Abstract
Parkinson disease (PD) is the second most common neurodegenerative disorder in elderly people. It is characterized by the aggregation of misfolded alpha-synuclein throughout the nervous system. Aside from cardinal motor symptoms, cognitive impairment is one of the most disabling non-motor symptoms that occurs during the progression of the disease. The accumulation and spreading of alpha-synuclein pathology from the brainstem to limbic and neocortical structures is correlated with emerging cognitive decline in PD. This review summarizes the genetic and pathophysiologic relationship between alpha-synuclein and cognitive impairment in PD, together with potential areas of biomarker advancement.
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12
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Unzipping the Secrets of Amyloid Disassembly by the Human Disaggregase. Cells 2021; 10:cells10102745. [PMID: 34685723 PMCID: PMC8534776 DOI: 10.3390/cells10102745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/08/2021] [Accepted: 10/08/2021] [Indexed: 01/08/2023] Open
Abstract
Neurodegenerative diseases (NDs) are increasingly positioned as leading causes of global deaths. The accelerated aging of the population and its strong relationship with neurodegeneration forecast these pathologies as a huge global health problem in the upcoming years. In this scenario, there is an urgent need for understanding the basic molecular mechanisms associated with such diseases. A major molecular hallmark of most NDs is the accumulation of insoluble and toxic protein aggregates, known as amyloids, in extracellular or intracellular deposits. Here, we review the current knowledge on how molecular chaperones, and more specifically a ternary protein complex referred to as the human disaggregase, deals with amyloids. This machinery, composed of the constitutive Hsp70 (Hsc70), the class B J-protein DnaJB1 and the nucleotide exchange factor Apg2 (Hsp110), disassembles amyloids of α-synuclein implicated in Parkinson’s disease as well as of other disease-associated proteins such as tau and huntingtin. We highlight recent studies that have led to the dissection of the mechanism used by this chaperone system to perform its disaggregase activity. We also discuss whether this chaperone-mediated disassembly mechanism could be used to solubilize other amyloidogenic substrates. Finally, we evaluate the implications of the chaperone system in amyloid clearance and associated toxicity, which could be critical for the development of new therapies.
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13
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Schechter M, Sharon R. An Emerging Role for Phosphoinositides in the Pathophysiology of Parkinson’s Disease. JOURNAL OF PARKINSON'S DISEASE 2021; 11:1725-1750. [PMID: 34151859 PMCID: PMC8609718 DOI: 10.3233/jpd-212684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Recent data support an involvement of defects in homeostasis of phosphoinositides (PIPs) in the pathophysiology of Parkinson’s disease (PD). Genetic mutations have been identified in genes encoding for PIP-regulating and PIP-interacting proteins, that are associated with familial and sporadic PD. Many of these proteins are implicated in vesicular membrane trafficking, mechanisms that were recently highlighted for their close associations with PD. PIPs are phosphorylated forms of the membrane phospholipid, phosphatidylinositol. Their composition in the vesicle’s membrane of origin, as well as membrane of destination, controls vesicular membrane trafficking. We review the converging evidence that points to the involvement of PIPs in PD. The review describes PD- and PIP-associated proteins implicated in clathrin-mediated endocytosis and autophagy, and highlights the involvement of α-synuclein in these mechanisms.
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Affiliation(s)
- Meir Schechter
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, Israel
| | - Ronit Sharon
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, Israel
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14
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Sarchione A, Marchand A, Taymans JM, Chartier-Harlin MC. Alpha-Synuclein and Lipids: The Elephant in the Room? Cells 2021; 10:2452. [PMID: 34572099 PMCID: PMC8467310 DOI: 10.3390/cells10092452] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 12/17/2022] Open
Abstract
Since the initial identification of alpha-synuclein (α-syn) at the synapse, numerous studies demonstrated that α-syn is a key player in the etiology of Parkinson's disease (PD) and other synucleinopathies. Recent advances underline interactions between α-syn and lipids that also participate in α-syn misfolding and aggregation. In addition, increasing evidence demonstrates that α-syn plays a major role in different steps of synaptic exocytosis. Thus, we reviewed literature showing (1) the interplay among α-syn, lipids, and lipid membranes; (2) advances of α-syn synaptic functions in exocytosis. These data underscore a fundamental role of α-syn/lipid interplay that also contributes to synaptic defects in PD. The importance of lipids in PD is further highlighted by data showing the impact of α-syn on lipid metabolism, modulation of α-syn levels by lipids, as well as the identification of genetic determinants involved in lipid homeostasis associated with α-syn pathologies. While questions still remain, these recent developments open the way to new therapeutic strategies for PD and related disorders including some based on modulating synaptic functions.
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Affiliation(s)
| | | | | | - Marie-Christine Chartier-Harlin
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172—LilNCog—Lille Neuroscience and Cognition, F-59000 Lille, France; (A.S.); (A.M.); (J.-M.T.)
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15
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Bettencourt C, Miki Y, Piras IS, de Silva R, Foti SC, Talboom JS, Revesz T, Lashley T, Balazs R, Viré E, Warner TT, Huentelman MJ, Holton JL. MOBP and HIP1 in multiple system atrophy: New α-synuclein partners in glial cytoplasmic inclusions implicated in the disease pathogenesis. Neuropathol Appl Neurobiol 2021; 47:640-652. [PMID: 33368549 PMCID: PMC8219819 DOI: 10.1111/nan.12688] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/16/2020] [Accepted: 12/14/2020] [Indexed: 01/02/2023]
Abstract
AIMS Multiple system atrophy (MSA) is a fatal neurodegenerative disease. Similar to Parkinson's disease (PD), MSA is an α-synucleinopathy, and its pathological hallmark consists of glial cytoplasmic inclusions (GCIs) containing α-synuclein (SNCA) in oligodendrocytes. We previously identified consistent changes in myelin-associated oligodendrocyte basic protein (MOBP) and huntingtin interacting protein 1 (HIP1) DNA methylation status in MSA. We hypothesized that if differential DNA methylation at these loci is mechanistically relevant for MSA, it should have downstream consequences on gene regulation. METHODS We investigated the relationship between MOBP and HIP1 DNA methylation and mRNA levels in cerebellar white matter from MSA and healthy controls. Additionally, we analysed protein expression using western blotting, immunohistochemistry and proximity ligation assays. RESULTS We found decreased MOBP mRNA levels significantly correlated with increased DNA methylation in MSA. For HIP1, we found a distinct relationship between DNA methylation and gene expression levels in MSA compared to healthy controls, suggesting this locus may be subjected to epigenetic remodelling in MSA. Although soluble protein levels for MOBP and HIP1 in cerebellar white matter were not significantly different between MSA cases and controls, we found striking differences between MSA and other neurodegenerative diseases, including PD and Huntington's disease. We also found that MOBP and HIP1 are mislocalized into the GCIs in MSA, where they appear to interact with SNCA. CONCLUSIONS This study supports a role for DNA methylation in downregulation of MOBP mRNA in MSA. Most importantly, the identification of MOBP and HIP1 as new constituents of GCIs emphasizes the relevance of these two loci to the pathogenesis of MSA.
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Affiliation(s)
- Conceição Bettencourt
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of Clinical and Movement NeurosciencesUCL Queen Square Institute of NeurologyLondonUK
| | - Yasuo Miki
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of NeuropathologyInstitute of Brain ScienceHirosaki University Graduate School of MedicineHirosakiJapan
| | - Ignazio S. Piras
- Neurogenomics DivisionTranslational Genomics Research InstitutePhoenixAZUSA
| | - Rohan de Silva
- Department of Clinical and Movement NeurosciencesUCL Queen Square Institute of NeurologyLondonUK
- Reta Lila Weston InstituteUCL Queen Square Institute of NeurologyLondonUK
| | - Sandrine C. Foti
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyLondonUK
| | - Joshua S. Talboom
- Neurogenomics DivisionTranslational Genomics Research InstitutePhoenixAZUSA
| | - Tamas Revesz
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Reta Lila Weston InstituteUCL Queen Square Institute of NeurologyLondonUK
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyLondonUK
| | - Tammaryn Lashley
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyLondonUK
| | - Robert Balazs
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of Neurodegenerative DiseaseUCL Queen Square Institute of NeurologyLondonUK
| | | | - Thomas T. Warner
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of Clinical and Movement NeurosciencesUCL Queen Square Institute of NeurologyLondonUK
- Reta Lila Weston InstituteUCL Queen Square Institute of NeurologyLondonUK
| | - Matt J. Huentelman
- Neurogenomics DivisionTranslational Genomics Research InstitutePhoenixAZUSA
| | - Janice L. Holton
- Queen Square Brain Bank for Neurological DisordersUCL Queen Square Institute of NeurologyLondonUK
- Department of Clinical and Movement NeurosciencesUCL Queen Square Institute of NeurologyLondonUK
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16
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Li D, McIntosh CS, Mastaglia FL, Wilton SD, Aung-Htut MT. Neurodegenerative diseases: a hotbed for splicing defects and the potential therapies. Transl Neurodegener 2021; 10:16. [PMID: 34016162 PMCID: PMC8136212 DOI: 10.1186/s40035-021-00240-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/23/2021] [Indexed: 12/14/2022] Open
Abstract
Precursor messenger RNA (pre-mRNA) splicing is a fundamental step in eukaryotic gene expression that systematically removes non-coding regions (introns) and ligates coding regions (exons) into a continuous message (mature mRNA). This process is highly regulated and can be highly flexible through a process known as alternative splicing, which allows for several transcripts to arise from a single gene, thereby greatly increasing genetic plasticity and the diversity of proteome. Alternative splicing is particularly prevalent in neuronal cells, where the splicing patterns are continuously changing to maintain cellular homeostasis and promote neurogenesis, migration and synaptic function. The continuous changes in splicing patterns and a high demand on many cis- and trans-splicing factors contribute to the susceptibility of neuronal tissues to splicing defects. The resultant neurodegenerative diseases are a large group of disorders defined by a gradual loss of neurons and a progressive impairment in neuronal function. Several of the most common neurodegenerative diseases involve some form of splicing defect(s), such as Alzheimer's disease, Parkinson's disease and spinal muscular atrophy. Our growing understanding of RNA splicing has led to the explosion of research in the field of splice-switching antisense oligonucleotide therapeutics. Here we review our current understanding of the effects alternative splicing has on neuronal differentiation, neuronal migration, synaptic maturation and regulation, as well as the impact on neurodegenerative diseases. We will also review the current landscape of splice-switching antisense oligonucleotides as a therapeutic strategy for a number of common neurodegenerative disorders.
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Affiliation(s)
- Dunhui Li
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Craig Stewart McIntosh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Frank Louis Mastaglia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Steve Donald Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - May Thandar Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia. .,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia.
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17
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Román-Vendrell C, Medeiros AT, Sanderson JB, Jiang H, Bartels T, Morgan JR. Effects of Excess Brain-Derived Human α-Synuclein on Synaptic Vesicle Trafficking. Front Neurosci 2021; 15:639414. [PMID: 33613189 PMCID: PMC7890186 DOI: 10.3389/fnins.2021.639414] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/18/2021] [Indexed: 11/13/2022] Open
Abstract
α-Synuclein is a presynaptic protein that regulates synaptic vesicle trafficking under physiological conditions. However, in several neurodegenerative diseases, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, α-synuclein accumulates throughout the neuron, including at synapses, leading to altered synaptic function, neurotoxicity, and motor, cognitive, and autonomic dysfunction. Neurons typically contain both monomeric and multimeric forms of α-synuclein, and it is generally accepted that disrupting the balance between them promotes aggregation and neurotoxicity. However, it remains unclear how distinct molecular species of α-synuclein affect synapses where α-synuclein is normally expressed. Using the lamprey reticulospinal synapse model, we previously showed that acute introduction of excess recombinant monomeric or dimeric α-synuclein impaired distinct stages of clathrin-mediated synaptic vesicle endocytosis, leading to a loss of synaptic vesicles. Here, we expand this knowledge by investigating the effects of native, physiological α-synuclein isolated from the brain of a neuropathologically normal human subject, which comprised predominantly helically folded multimeric α-synuclein with a minor component of monomeric α-synuclein. After acute introduction of excess brain-derived human α-synuclein, there was a moderate reduction in the synaptic vesicle cluster and an increase in the number of large, atypical vesicles called "cisternae." In addition, brain-derived α-synuclein increased synaptic vesicle and cisternae sizes and induced atypical fusion/fission events at the active zone. In contrast to monomeric or dimeric α-synuclein, the brain-derived multimeric α-synuclein did not appear to alter clathrin-mediated synaptic vesicle endocytosis. Taken together, these data suggest that excess brain-derived human α-synuclein impairs intracellular vesicle trafficking and further corroborate the idea that different molecular species of α-synuclein produce distinct trafficking defects at synapses. These findings provide insights into the mechanisms by which excess α-synuclein contributes to synaptic deficits and disease phenotypes.
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Affiliation(s)
- Cristina Román-Vendrell
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Audrey T Medeiros
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - John B Sanderson
- Harvard Medical School, Brigham and Women's Hospital, Boston, MA, United States
| | - Haiyang Jiang
- Harvard Medical School, Brigham and Women's Hospital, Boston, MA, United States
| | - Tim Bartels
- UK Dementia Research Institute, University College London, London, United Kingdom
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
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18
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Fakhree MAA, Konings IBM, Kole J, Cambi A, Blum C, Claessens MMAE. The Localization of Alpha-synuclein in the Endocytic Pathway. Neuroscience 2021; 457:186-195. [PMID: 33482328 DOI: 10.1016/j.neuroscience.2021.01.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 01/24/2023]
Abstract
Alpha-synuclein (αS) is an intrinsically disordered protein (IDP) that is abundantly present in the brain and is associated with Parkinson's disease (PD). In spite of its abundance and its contribution to PD pathogenesis, the exact cellular function of αS remains largely unknown. The ability of αS to remodel phospholipid model membranes combined with biochemical and cellular studies suggests that αS is involved in endocytosis. To unravel with which route(s) and stage(s) of the endocytic pathway αS is associated, we quantified the colocalization between αS and endocytic marker proteins in differentiated SH-SY5Y neuronal cells, using an object based colocalization analysis. Comparison with randomized data allowed us to discriminate between structural and coincidental colocalizations. A large fraction of the αS positive vesicles colocalizes with caveolin positive vesicles, a smaller fraction colocalizes with EEA1 and Rab7. We find no structural colocalization between αS and clathrin and Rab11 positive vesicles. We conclude that in a physiological context, αS is structurally associated with caveolin dependent membrane vesiculation and is found further along the endocytic pathway, in decreasing amounts, on early and late endosomes. Our results not only shed new light on the function of αS, they also provide a possible link between αS function and vesicle trafficking malfunction in PD.
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Affiliation(s)
- Mohammad A A Fakhree
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Irene B M Konings
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jeroen Kole
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Alessandra Cambi
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, The Netherlands
| | - Christian Blum
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Mireille M A E Claessens
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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19
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Schechter M, Atias M, Abd Elhadi S, Davidi D, Gitler D, Sharon R. α-Synuclein facilitates endocytosis by elevating the steady-state levels of phosphatidylinositol 4,5-bisphosphate. J Biol Chem 2020; 295:18076-18090. [PMID: 33087443 PMCID: PMC7939461 DOI: 10.1074/jbc.ra120.015319] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/08/2020] [Indexed: 12/12/2022] Open
Abstract
α-Synuclein (α-Syn) is a protein implicated in the pathogenesis of Parkinson's disease (PD). It is an intrinsically disordered protein that binds acidic phospholipids. Growing evidence supports a role for α-Syn in membrane trafficking, including, mechanisms of endocytosis and exocytosis, although the exact role of α-Syn in these mechanisms is currently unclear. Here we investigate the associations of α-Syn with the acidic phosphoinositides (PIPs), phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2). Our results show that α-Syn colocalizes with PIP2 and the phosphorylated active form of the clathrin adaptor protein 2 (AP2) at clathrin-coated pits. Using endocytosis of transferrin as an indicator for clathrin-mediated endocytosis (CME), we find that α-Syn involvement in endocytosis is specifically mediated through PI(4,5)P2 levels on the plasma membrane. In accord with their effects on PI(4,5)P2 levels, the PD associated A30P, E46K, and A53T mutations in α-Syn further enhance CME in neuronal and nonneuronal cells. However, lysine to glutamic acid substitutions at the KTKEGV repeat domain of α-Syn, which interfere with phospholipid binding, are ineffective in enhancing CME. We further show that the rate of synaptic vesicle (SV) endocytosis is differentially affected by the α-Syn mutations and associates with their effects on PI(4,5)P2 levels, however, with the exception of the A30P mutation. This study provides evidence for a critical involvement of PIPs in α-Syn-mediated membrane trafficking.
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Affiliation(s)
- Meir Schechter
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Merav Atias
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Suaad Abd Elhadi
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Dana Davidi
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ronit Sharon
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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20
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Larsen K, Bæk R, Sahin C, Kjær L, Christiansen G, Nielsen J, Farajzadeh L, Otzen DE. Molecular characteristics of porcine alpha-synuclein splicing variants. Biochimie 2020; 180:121-133. [PMID: 33152422 DOI: 10.1016/j.biochi.2020.10.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 10/05/2020] [Accepted: 10/30/2020] [Indexed: 12/15/2022]
Abstract
Alpha-synuclein (α-syn) is a 140 amino acid, intrinsically disordered protein with a potential role in neurotransmitter vesicle release. The protein is natively unfolded under physiological conditions, and is expressed predominantly in neural tissue. α-syn is associated with neuropathological conditions in Parkinson's disease, where the protein misfolds into oligomers and fibrils resulting in aggregates in Lewy bodies. Here we report the molecular cloning of SNCA cDNA encoding porcine α-syn and transcript variants hereof. Six transcripts coding for porcine α-syn are presented in the report, of which three result from exon skipping, generating in-frame splicing of coding exons 3 and 5. The splicing pattern of these alternative spliced variants is conserved between human and pig. All the observed in-frame deletions yield significantly shorter α-syn proteins compared with the 140 amino acid full-length protein. Expression analysis performed by real-time quantitative RT-PCR revealed a differential expression of the six transcript splicing variants in different pig organs and tissues. Common for all splicing variants, a very high transcript expression was detected in brain tissues and in spinal cord and very low or no expression outside the central nervous system. The porcine α-syn protein demonstrated markedly different biophysical characteristics compared with its human counterpart. No fibrillation of porcine α-syn was observed with the pig wild-type α-syn and A30P α-syn, and both variants show significantly reduced ability to bind to lipid vesicles. Overexpression of mutated porcine α-syn might recapitulate the human PD pathogenesis and lead to the identification of genetic modifiers of the disease.
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Affiliation(s)
- Knud Larsen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, DK-8000, Aarhus C, Denmark.
| | - Rikke Bæk
- Department of Clinical Immunology, Aalborg University Hospital, Urbansgade 32, DK-9000, Aalborg, Denmark.
| | - Cagla Sahin
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus C, Denmark.
| | - Lars Kjær
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus C, Denmark.
| | - Gunna Christiansen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, DK-8000, Aarhus C, Denmark.
| | - Janni Nielsen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus C, Denmark.
| | - Leila Farajzadeh
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, DK-8000, Aarhus C, Denmark.
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus C, Denmark.
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