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Röntgen A, Toprakcioglu Z, Tomkins JE, Vendruscolo M. Modulation of α-synuclein in vitro aggregation kinetics by its alternative splice isoforms. Proc Natl Acad Sci U S A 2024; 121:e2313465121. [PMID: 38324572 PMCID: PMC10873642 DOI: 10.1073/pnas.2313465121] [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: 08/05/2023] [Accepted: 12/20/2023] [Indexed: 02/09/2024] Open
Abstract
The misfolding and aggregation of α-synuclein is linked to a family of neurodegenerative disorders known as synucleinopathies, the most prominent of which is Parkinson's disease (PD). Understanding the aggregation process of α-synuclein from a mechanistic point of view is thus of key importance. SNCA, the gene encoding α-synuclein, comprises six exons and produces various isoforms through alternative splicing. The most abundant isoform is expressed as a 140-amino acid protein (αSyn-140), while three other isoforms, αSyn-126, αSyn-112, and αSyn-98, are generated by skipping exon 3, exon 5, or both exons, respectively. In this study, we performed a detailed biophysical characterization of the aggregation of these four isoforms. We found that αSyn-112 and αSyn-98 exhibit accelerated aggregation kinetics compared to αSyn-140 and form distinct aggregate morphologies, as observed by transmission electron microscopy. Moreover, we observed that the presence of relatively small amounts of αSyn-112 accelerates the aggregation of αSyn-140, significantly reducing the aggregation half-time. These results indicate a potential role of alternative splicing in the pathological aggregation of α-synuclein and provide insights into how this process could be associated with the development of synucleinopathies.
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Affiliation(s)
- Alexander Röntgen
- Centre for Misfolding Diseases, Yusuf HamiedDepartment of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
| | - Zenon Toprakcioglu
- Centre for Misfolding Diseases, Yusuf HamiedDepartment of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
| | - James E. Tomkins
- Centre for Misfolding Diseases, Yusuf HamiedDepartment of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Yusuf HamiedDepartment of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
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2
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Goddard TR, Brookes KJ, Sharma R, Moemeni A, Rajkumar AP. Dementia with Lewy Bodies: Genomics, Transcriptomics, and Its Future with Data Science. Cells 2024; 13:223. [PMID: 38334615 PMCID: PMC10854541 DOI: 10.3390/cells13030223] [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: 12/14/2023] [Revised: 01/17/2024] [Accepted: 01/23/2024] [Indexed: 02/10/2024] Open
Abstract
Dementia with Lewy bodies (DLB) is a significant public health issue. It is the second most common neurodegenerative dementia and presents with severe neuropsychiatric symptoms. Genomic and transcriptomic analyses have provided some insight into disease pathology. Variants within SNCA, GBA, APOE, SNCB, and MAPT have been shown to be associated with DLB in repeated genomic studies. Transcriptomic analysis, conducted predominantly on candidate genes, has identified signatures of synuclein aggregation, protein degradation, amyloid deposition, neuroinflammation, mitochondrial dysfunction, and the upregulation of heat-shock proteins in DLB. Yet, the understanding of DLB molecular pathology is incomplete. This precipitates the current clinical position whereby there are no available disease-modifying treatments or blood-based diagnostic biomarkers. Data science methods have the potential to improve disease understanding, optimising therapeutic intervention and drug development, to reduce disease burden. Genomic prediction will facilitate the early identification of cases and the timely application of future disease-modifying treatments. Transcript-level analyses across the entire transcriptome and machine learning analysis of multi-omic data will uncover novel signatures that may provide clues to DLB pathology and improve drug development. This review will discuss the current genomic and transcriptomic understanding of DLB, highlight gaps in the literature, and describe data science methods that may advance the field.
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Affiliation(s)
- Thomas R. Goddard
- Mental Health and Clinical Neurosciences Academic Unit, Institute of Mental Health, School of Medicine, University of Nottingham, Nottingham NG7 2TU, UK
| | - Keeley J. Brookes
- Department of Biosciences, School of Science & Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
| | - Riddhi Sharma
- Biodiscovery Institute, School of Medicine, University of Nottingham, Nottingham NG7 2RD, UK
- UK Health Security Agency, Radiation Effects Department, Radiation Protection Science Division, Harwell Science Campus, Didcot, Oxfordshire OX11 0RQ, UK
| | - Armaghan Moemeni
- School of Computer Science, University of Nottingham, Nottingham NG8 1BB, UK
| | - Anto P. Rajkumar
- Mental Health and Clinical Neurosciences Academic Unit, Institute of Mental Health, School of Medicine, University of Nottingham, Nottingham NG7 2TU, UK
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Sastre D, Zafar F, Torres CAM, Piper D, Kirik D, Sanders LH, Qi LS, Schüle B. Inactive S. aureus Cas9 downregulates alpha-synuclein and reduces mtDNA damage and oxidative stress levels in human stem cell model of Parkinson's disease. Sci Rep 2023; 13:17796. [PMID: 37853101 PMCID: PMC10584834 DOI: 10.1038/s41598-023-45078-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 10/16/2023] [Indexed: 10/20/2023] Open
Abstract
Parkinson's disease (PD) is one of the most common neurodegenerative diseases, but no disease modifying therapies have been successful in clinical translation presenting a major unmet medical need. A promising target is alpha-synuclein or its aggregated form, which accumulates in the brain of PD patients as Lewy bodies. While it is not entirely clear which alpha-synuclein protein species is disease relevant, mere overexpression of alpha-synuclein in hereditary forms leads to neurodegeneration. To specifically address gene regulation of alpha-synuclein, we developed a CRISPR interference (CRISPRi) system based on the nuclease dead S. aureus Cas9 (SadCas9) fused with the transcriptional repressor domain Krueppel-associated box to controllably repress alpha-synuclein expression at the transcriptional level. We screened single guide (sg)RNAs across the SNCA promoter and identified several sgRNAs that mediate downregulation of alpha-synuclein at varying levels. CRISPRi downregulation of alpha-synuclein in iPSC-derived neuronal cultures from a patient with an SNCA genomic triplication showed functional recovery by reduction of oxidative stress and mitochondrial DNA damage. Our results are proof-of-concept in vitro for precision medicine by targeting the SNCA gene promoter. The SNCA CRISPRi approach presents a new model to understand safe levels of alpha-synuclein downregulation and a novel therapeutic strategy for PD and related alpha-synucleinopathies.
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Affiliation(s)
- Danuta Sastre
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Dr., R271/217, Stanford, CA, 94305, USA
| | - Faria Zafar
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Dr., R271/217, Stanford, CA, 94305, USA
| | - C Alejandra Morato Torres
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Dr., R271/217, Stanford, CA, 94305, USA
| | - Desiree Piper
- Department of Biological Sciences, San Jose State University, San Jose, CA, 95192, USA
| | - Deniz Kirik
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Laurie H Sanders
- Departments of Neurology and Pathology, Duke Center for Neurodegeneration and Neurotherapeutics, Duke University Medical Center, Durham, NC, 27710, USA
| | - L Stanley Qi
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Birgitt Schüle
- Department of Pathology, Stanford University School of Medicine, 300 Pasteur Dr., R271/217, Stanford, CA, 94305, USA.
- Biosciences Division, SRI International, Menlo Park, CA, 94025, USA.
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4
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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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5
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Sensi SL, Russo M, Tiraboschi P. Biomarkers of diagnosis, prognosis, pathogenesis, response to therapy: Convergence or divergence? Lessons from Alzheimer's disease and synucleinopathies. HANDBOOK OF CLINICAL NEUROLOGY 2023; 192:187-218. [PMID: 36796942 DOI: 10.1016/b978-0-323-85538-9.00015-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Alzheimer's disease (AD) is the most common disorder associated with cognitive impairment. Recent observations emphasize the pathogenic role of multiple factors inside and outside the central nervous system, supporting the notion that AD is a syndrome of many etiologies rather than a "heterogeneous" but ultimately unifying disease entity. Moreover, the defining pathology of amyloid and tau coexists with many others, such as α-synuclein, TDP-43, and others, as a rule, not an exception. Thus, an effort to shift our AD paradigm as an amyloidopathy must be reconsidered. Along with amyloid accumulation in its insoluble state, β-amyloid is becoming depleted in its soluble, normal states, as a result of biological, toxic, and infectious triggers, requiring a shift from convergence to divergence in our approach to neurodegeneration. These aspects are reflected-in vivo-by biomarkers, which have become increasingly strategic in dementia. Similarly, synucleinopathies are primarily characterized by abnormal deposition of misfolded α-synuclein in neurons and glial cells and, in the process, depleting the levels of the normal, soluble α-synuclein that the brain needs for many physiological functions. The soluble to insoluble conversion also affects other normal brain proteins, such as TDP-43 and tau, accumulating in their insoluble states in both AD and dementia with Lewy bodies (DLB). The two diseases have been distinguished by the differential burden and distribution of insoluble proteins, with neocortical phosphorylated tau deposition more typical of AD and neocortical α-synuclein deposition peculiar to DLB. We propose a reappraisal of the diagnostic approach to cognitive impairment from convergence (based on clinicopathologic criteria) to divergence (based on what differs across individuals affected) as a necessary step for the launch of precision medicine.
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Affiliation(s)
- Stefano L Sensi
- Department of Neuroscience, Imaging, and Clinical Sciences, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Molecular Neurology Unit, Center for Advanced Studies and Technology-CAST and ITAB Institute for Advanced Biotechnology, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy.
| | - Mirella Russo
- Department of Neuroscience, Imaging, and Clinical Sciences, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Molecular Neurology Unit, Center for Advanced Studies and Technology-CAST and ITAB Institute for Advanced Biotechnology, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Pietro Tiraboschi
- Division of Neurology V-Neuropathology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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Sastre D, Zafar F, Torres CAM, Piper D, Kirik D, Sanders LH, Qi S, Schüle B. Nuclease-dead S. aureus Cas9 downregulates alpha-synuclein and reduces mtDNA damage and oxidative stress levels in patient-derived stem cell model of Parkinson's disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.24.525105. [PMID: 36747875 PMCID: PMC9900844 DOI: 10.1101/2023.01.24.525105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Parkinson's disease (PD) is one of the most common neurodegenerative diseases, but no disease modifying therapies have been successful in clinical translation presenting a major unmet medical need. A promising target is alpha-synuclein or its aggregated form, which accumulates in the brain of PD patients as Lewy bodies. While it is not entirely clear which alpha-synuclein protein species is disease relevant, mere overexpression of alpha-synuclein in hereditary forms leads to neurodegeneration. To specifically address gene regulation of alpha-synuclein, we developed a CRISPR interference (CRISPRi) system based on the nuclease dead S. aureus Cas9 (SadCas9) fused with the transcriptional repressor domain Krueppel-associated box to controllably repress alpha-synuclein expression at the transcriptional level. We screened single guide (sg)RNAs across the SNCA promoter and identified several sgRNAs that mediate downregulation of alpha-synuclein at varying levels. CRISPRi downregulation of alpha-synuclein in iPSC-derived neuronal cultures from a patient with an SNCA genomic triplication showed functional recovery by reduction of oxidative stress and mitochondrial DNA damage. Our results are proof-of-concept in vitro for precision medicine by targeting the SNCA gene promoter. The SNCA CRISPRi approach presents a new model to understand safe levels of alpha-synuclein downregulation and a novel therapeutic strategy for PD and related alpha-synucleinopathies.
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Affiliation(s)
- Danuta Sastre
- Stanford University School of Medicine, Department of Pathology, Stanford, CA 94305, U.S.A
| | - Faria Zafar
- Stanford University School of Medicine, Department of Pathology, Stanford, CA 94305, U.S.A
| | | | - Desiree Piper
- San Jose State University, Department of Biological Sciences, San Jose, 95192 CA, U.S.A
| | - Deniz Kirik
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Laurie H. Sanders
- Departments of Neurology and Pathology, Duke Center for Neurodegeneration and Neurotherapeutics, Duke University Medical Center, Durham, NC 27710, U.S.A
| | - Stanley Qi
- Stanford University, Department of Bioengineering, Stanford, CA 94305, U.S.A
| | - Birgitt Schüle
- Stanford University School of Medicine, Department of Pathology, Stanford, CA 94305, U.S.A
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Scheibe C, Karreman C, Schildknecht S, Leist M, Hauser K. Synuclein Family Members Prevent Membrane Damage by Counteracting α-Synuclein Aggregation. Biomolecules 2021; 11:biom11081067. [PMID: 34439733 DOI: 10.3390/biom11081067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 01/09/2023] Open
Abstract
The 140 amino acid protein α-synuclein (αS) is an intrinsically disordered protein (IDP) with various roles and locations in healthy neurons that plays a key role in Parkinson's disease (PD). Contact with biomembranes can lead to α-helical conformations, but can also act as s seeding event for aggregation and a predominant β-sheet conformation. In PD patients, αS is found to aggregate in various fibrillary structures, and the shift in aggregation and localization is associated with disease progression. Besides full-length αS, several related polypeptides are present in neurons. The role of many αS-related proteins in the aggregation of αS itself is not fully understood Two of these potential aggregation modifiers are the αS splicing variant αS Δexon3 (Δ3) and the paralog β-synuclein (βS). Here, polarized ATR-FTIR spectroscopy was used to study the membrane interaction of these proteins individually and in various combinations. The method allowed a continuous monitoring of both the lipid structure of biomimetic membranes and the aggregation state of αS and related proteins. The use of polarized light also revealed the orientation of secondary structure elements. While αS led to a destruction of the lipid membrane upon membrane-catalyzed aggregation, βS and Δ3 aggregated significantly less, and they did not harm the membrane. Moreover, the latter proteins reduced the membrane damage triggered by αS. There were no major differences in the membrane interaction for the different synuclein variants. In combination, these observations suggest that the formation of particular protein aggregates is the major driving force for αS-driven membrane damage. The misbalance of αS, βS, and Δ3 might therefore play a crucial role in neurodegenerative disease.
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Affiliation(s)
- Christian Scheibe
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | | | - Stefan Schildknecht
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
- Department of Life Sciences, Albstadt-Sigmaringen University of Applied Sciences, 72488 Sigmaringen, Germany
| | - Marcel Leist
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Karin Hauser
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
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8
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Alpha-synuclein increases in rodent and human spinal cord injury and promotes inflammation and tissue loss. Sci Rep 2021; 11:11720. [PMID: 34083630 PMCID: PMC8175699 DOI: 10.1038/s41598-021-91116-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 05/17/2021] [Indexed: 12/27/2022] Open
Abstract
Synucleinopathies are neurodegenerative diseases in which α-synuclein protein accumulates in neurons and glia. In these diseases, α-synuclein forms dense intracellular aggregates that are disease hallmarks and actively contribute to tissue pathology. Interestingly, many pathological mechanisms, including iron accumulation and lipid peroxidation, are shared between classical synucleinopathies such as Alzheimer’s disease, Parkinson’s disease and traumatic spinal cord injury (SCI). However, to date, no studies have determined if α-synuclein accumulation occurs after human SCI. To examine this, cross-sections from injured and non-injured human spinal cords were immunolabeled for α-synuclein. This showed robust α-synuclein accumulation in profiles resembling axons and astrocytes in tissue surrounding the injury, revealing that α-synuclein markedly aggregates in traumatically injured human spinal cords. We also detected significant iron deposition in the injury site, a known catalyst for α-synuclein aggregation. Next a rodent SCI model mimicking the histological features of human SCI revealed aggregates and structurally altered monomers of α-synuclein are present after SCI. To determine if α-synuclein exacerbates SCI pathology, α-synuclein knockout mice were tested. Compared to wild type mice, α-synuclein knockout mice had significantly more spared axons and neurons and lower pro-inflammatory mediators, macrophage accumulation, and iron deposition in the injured spinal cord. Interestingly, locomotor analysis revealed that α-synuclein may be essential for dopamine-mediated hindlimb function after SCI. Collectively, the marked upregulation and long-lasting accumulation of α-synuclein and iron suggests that SCI may fit within the family of synucleinopathies and offer new therapeutic targets for promoting neuron preservation and improving function after spinal trauma.
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Abstract
OBJECTIVES Lewy body dementia (LBD) is the second most prevalent neurodegenerative dementia and it causes more morbidity and mortality than Alzheimer's disease. Several genetic associations of LBD have been reported and their functional implications remain uncertain. Hence, we aimed to do a systematic review of all gene expression studies that investigated people with LBD for improving our understanding of LBD molecular pathology and for facilitating discovery of novel biomarkers and therapeutic targets for LBD. METHODS We systematically reviewed five online databases (PROSPERO protocol: CRD42017080647) and assessed the functional implications of all reported differentially expressed genes (DEGs) using Ingenuity Pathway Analyses. RESULTS We screened 3,809 articles and identified 31 eligible studies. In that, 1,242 statistically significant (p < 0.05) DEGs including 70 microRNAs have been reported in people with LBD. Expression levels of alternatively spliced transcripts of SNCA, SNCB, PRKN, APP, RELA, and ATXN2 significantly differ in LBD. Several mitochondrial genes and genes involved in ubiquitin proteasome system and autophagy-lysosomal pathway were significantly downregulated in LBD. Evidence supporting chronic neuroinflammation in LBD was inconsistent. Our functional analyses highlighted the importance of ribonucleic acid (RNA)-mediated gene silencing, neuregulin signalling, and neurotrophic factors in the molecular pathology of LBD. CONCLUSIONS α-synuclein aggregation, mitochondrial dysfunction, defects in molecular networks clearing misfolded proteins, and RNA-mediated gene silencing contribute to neurodegeneration in LBD. Larger longitudinal transcriptomic studies investigating biological fluids of people living with LBD are needed for molecular subtyping and staging of LBD. Diagnostic biomarker potential and therapeutic promise of identified DEGs warrant further research.
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Cahill CM, Aleyadeh R, Gao J, Wang C, Rogers JT. Alpha-Synuclein in Alcohol Use Disorder, Connections with Parkinson's Disease and Potential Therapeutic Role of 5' Untranslated Region-Directed Small Molecules. Biomolecules 2020; 10:E1465. [PMID: 33096655 PMCID: PMC7589448 DOI: 10.3390/biom10101465] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/28/2020] [Accepted: 10/09/2020] [Indexed: 12/23/2022] Open
Abstract
Alpha-synuclein (α-Syn) is a 140-amino acid (aa) protein encoded by the Synuclein alpha SNCA gene. It is the synaptic protein associated with Parkinson's disease (PD) and is the most highly expressed protein in the Lewy bodies associated with PD and other alpha synucleopathies, including Lewy body dementia (LBD) and multiple system atrophy (MSA). Iron deposits are present in the core of Lewy bodies, and there are reports suggesting that divalent metal ions including Cu2+ and Fe2+ enhance the aggregation of α-Syn. Differential expression of α-Syn is associated with alcohol use disorder (AUD), and specific genetic variants contribute to the risk for alcoholism, including alcohol craving. Spliced variants of α-Syn, leading to the expression of several shorter forms which are more prone to aggregation, are associated with both PD and AUD, and common transcript variants may be able to predict at-risk populations for some movement disorders or subtypes of PD, including secondary Parkinsonism. Both PD and AUD are associated with liver and brain iron dyshomeostasis. Research over the past decade has shown that α-Syn has iron import functions with an ability to oxidize the Fe3+ form of iron to Fe2+ to facilitate its entry into cells. Our prior research has identified an iron-responsive element (IRE) in the 5' untranslated region (5'UTR) of α-Syn mRNA, and we have used the α-Syn 5'UTR to screen for small molecules that modulate its expression in the H4 neuronal cell line. These screens have led us to identify several interesting small molecules capable of both decreasing and increasing α-Syn expression and that may have the potential, together with the recently described mesenchymal stem cell therapies, to normalize α-Syn expression in different regions of the alcoholic and PD brain.
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Affiliation(s)
- Catherine M. Cahill
- Neurochemistry Laboratory, Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA;
| | | | - Jin Gao
- Department of Clinical Psychology, Qilu Hospital of Shandong University, Qingdao 266011, China;
| | - Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA;
| | - Jack T. Rogers
- Neurochemistry Laboratory, Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA;
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Tseng E, Rowell WJ, Glenn OC, Hon T, Barrera J, Kujawa S, Chiba-Falek O. The Landscape of SNCA Transcripts Across Synucleinopathies: New Insights From Long Reads Sequencing Analysis. Front Genet 2019; 10:584. [PMID: 31338105 PMCID: PMC6629766 DOI: 10.3389/fgene.2019.00584] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 06/04/2019] [Indexed: 11/21/2022] Open
Abstract
Dysregulation of alpha-synuclein expression has been implicated in the pathogenesis of synucleinopathies, in particular Parkinson's Disease (PD) and Dementia with Lewy bodies (DLB). Previous studies have shown that the alternatively spliced isoforms of the SNCA gene are differentially expressed in different parts of the brain for PD and DLB patients. Similarly, SNCA isoforms with skipped exons can have a functional impact on the protein domains. The large intronic region of the SNCA gene was also shown to harbor structural variants that affect transcriptional levels. Here, we apply the first study of using long read sequencing with targeted capture of both the gDNA and cDNA of the SNCA gene in brain tissues of PD, DLB, and control samples using the PacBio Sequel system. The targeted full-length cDNA (Iso-Seq) data confirmed complex usage of known alternative start sites and variable 3' UTR lengths, as well as novel 5' starts and 3' ends not previously described. The targeted gDNA data allowed phasing of up to 81% of the ~114 kb SNCA region, with the longest phased block exceeding 54 kb. We demonstrate that long gDNA and cDNA reads have the potential to reveal long-range information not previously accessible using traditional sequencing methods. This approach has a potential impact in studying disease risk genes such as SNCA, providing new insights into the genetic etiologies, including perturbations to the landscape the gene transcripts, of human complex diseases such as synucleinopathies.
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Affiliation(s)
| | | | - Omolara-Chinue Glenn
- Department of Neurology, Duke University Medical Center, Durham, NC, United States
- Center for Genomic and Computational Biology, Duke University Medical Center, Durham, NC, United States
| | - Ting Hon
- Pacific Biosciences, Menlo Park, CA, United States
| | - Julio Barrera
- Department of Neurology, Duke University Medical Center, Durham, NC, United States
- Center for Genomic and Computational Biology, Duke University Medical Center, Durham, NC, United States
| | - Steve Kujawa
- Pacific Biosciences, Menlo Park, CA, United States
| | - Ornit Chiba-Falek
- Department of Neurology, Duke University Medical Center, Durham, NC, United States
- Center for Genomic and Computational Biology, Duke University Medical Center, Durham, NC, United States
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12
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Piper DA, Sastre D, Schüle B. Advancing Stem Cell Models of Alpha-Synuclein Gene Regulation in Neurodegenerative Disease. Front Neurosci 2018; 12:199. [PMID: 29686602 PMCID: PMC5900030 DOI: 10.3389/fnins.2018.00199] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 03/13/2018] [Indexed: 12/15/2022] Open
Abstract
Alpha-synuclein (non A4 component of amyloid precursor, SNCA, NM_000345.3) plays a central role in the pathogenesis of Parkinson's disease (PD) and related Lewy body disorders such as Parkinson's disease dementia, Lewy body dementia, and multiple system atrophy. Since its discovery as a disease-causing gene in 1997, alpha-synuclein has been a central point of scientific interest both at the protein and gene level. Mutations, including copy number variants, missense mutations, short structural variants, and single nucleotide polymorphisms, can be causative for PD and affect conformational changes of the protein, can contribute to changes in expression of alpha-synuclein and its isoforms, and can influence regulation of temporal as well as spatial levels of alpha-synuclein in different tissues and cell types. A lot of progress has been made to understand both the physiological transcriptional and epigenetic regulation of the alpha-synuclein gene and whether changes in transcriptional regulation could lead to disease and neurodegeneration in PD and related alpha-synucleinopathies. Although the histopathological changes in these neurodegenerative disorders are similar, the temporal and spatial presentation and progression distinguishes them which could be in part due to changes or disruption of transcriptional regulation of alpha-synuclein. In this review, we describe different genetic alterations that contribute to PD and neurodegenerative conditions and review aspects of transcriptional regulation of the alpha-synuclein gene in the context of the development of PD. New technologies, advanced gene engineering and stem cell modeling, are on the horizon to shed further light on a better understanding of gene regulatory processes and exploit them for therapeutic developments.
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Affiliation(s)
- Desiree A Piper
- Parkinson's Institute and Clinical Center, Sunnyvale, CA, United States
| | - Danuta Sastre
- Parkinson's Institute and Clinical Center, Sunnyvale, CA, United States
| | - Birgitt Schüle
- Parkinson's Institute and Clinical Center, Sunnyvale, CA, United States
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13
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Structural variants in SNCA gene and the implication to synucleinopathies. Curr Opin Genet Dev 2017; 44:110-116. [PMID: 28319736 DOI: 10.1016/j.gde.2017.01.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 01/30/2017] [Indexed: 01/23/2023]
Abstract
Synucleinopathies are a group of neurodegenerative diseases that share a common pathological lesion of intracellular protein inclusions largely composed of aggregates of alpha-synuclein protein. Accumulating evidence, including genome-wide association studies, has implicated the alpha-synuclein (SNCA) gene in the etiology of synucleinopathies and it has been suggested that SNCA expression levels are critical for the development of these diseases. This review focuses on genetic variants from the class of structural variants (SVs), including multiplication of large genomic segments and short (<50bp) genomic variants such as simple sequence repeats (SSRs), within the SNCA locus. We provide evidence that SNCA-SVs play a key role in the pathogenesis of synucleinopathies via their effects on gene expression and on regulatory mechanisms including transcription and splicing.
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Benskey MJ, Perez RG, Manfredsson FP. The contribution of alpha synuclein to neuronal survival and function - Implications for Parkinson's disease. J Neurochem 2016; 137:331-59. [PMID: 26852372 PMCID: PMC5021132 DOI: 10.1111/jnc.13570] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 01/29/2016] [Indexed: 02/06/2023]
Abstract
The aggregation of alpha synuclein (α-syn) is a neuropathological feature that defines a spectrum of disorders collectively termed synucleinopathies, and of these, Parkinson's disease (PD) is arguably the best characterized. Aggregated α-syn is the primary component of Lewy bodies, the defining pathological feature of PD, while mutations or multiplications in the α-syn gene result in familial PD. The high correlation between α-syn burden and PD has led to the hypothesis that α-syn aggregation produces toxicity through a gain-of-function mechanism. However, α-syn has been implicated to function in a diverse range of essential cellular processes such as the regulation of neurotransmission and response to cellular stress. As such, an alternative hypothesis with equal explanatory power is that the aggregation of α-syn results in toxicity because of a toxic loss of necessary α-syn function, following sequestration of functional forms α-syn into insoluble protein aggregates. Within this review, we will provide an overview of the literature linking α-syn to PD and the knowledge gained from current α-syn-based animal models of PD. We will then interpret these data from the viewpoint of the α-syn loss-of-function hypothesis and provide a potential mechanistic model by which loss of α-syn function could result in at least some of the neurodegeneration observed in PD. By providing an alternative perspective on the etiopathogenesis of PD and synucleinopathies, this may reveal alternative avenues of research in order to identify potential novel therapeutic targets for disease modifying strategies. The correlation between α-synuclein burden and Parkinson's disease pathology has led to the hypothesis that α-synuclein aggregation produces toxicity through a gain-of-function mechanism. However, in this review, we discuss data supporting the alternative hypothesis that the aggregation of α-synuclein results in toxicity because of loss of necessary α-synuclein function at the presynaptic terminal, following sequestration of functional forms of α-synuclein into aggregates.
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Affiliation(s)
- Matthew J Benskey
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, Michigan, USA
| | - Ruth G Perez
- Department of Biomedical Sciences, Center of Emphasis in Neuroscience, Paul L. Foster School of Medicine, Texas Tech University of the Health Sciences El Paso, El Paso, Texas, USA
| | - Fredric P Manfredsson
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, Michigan, USA
- Hauenstein Neuroscience Center, Mercy Health Saint Mary's, Grand Rapids, Michigan, USA
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Tagliafierro L, Chiba-Falek O. Up-regulation of SNCA gene expression: implications to synucleinopathies. Neurogenetics 2016; 17:145-57. [PMID: 26948950 DOI: 10.1007/s10048-016-0478-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/27/2016] [Indexed: 01/06/2023]
Abstract
Synucleinopathies are a group of neurodegenerative diseases that share a common pathological lesion of intracellular protein inclusions largely composed by aggregates of alpha-synuclein protein. Accumulating evidence, including genome wide association studies, has implicated alpha-synuclein (SNCA) gene in the etiology of synucleinopathies. However, the precise variants within SNCA gene that contribute to the sporadic forms of Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and other synucleinopathies and their molecular mechanisms of action remain elusive. It has been suggested that SNCA expression levels are critical for the development of these diseases. Here, we review several model systems that have been developed to advance the understanding of the role of SNCA expression levels in the etiology of synucleinopathies. We also describe different molecular mechanisms that regulate SNCA gene expression and discuss possible strategies for SNCA down-regulation as means for therapeutic approaches. Finally, we highlight some examples that underscore the relationships between the genetic association findings and the regulatory mechanisms of SNCA expression, which suggest that genetic variability in SNCA locus is directly responsible, at least in part, to the changes in gene expression and explain the reported associations of SNCA with synucleinopathies. Future studies utilizing induced pluripotent stem cells (iPSCs)-derived neuronal lines and genome editing by CRISPR/Cas9, will allow us to validate, characterize, and manipulate the effects of particular cis-genetic variants on SNCA expression. Moreover, this model system will enable us to compare different neuronal and glial lineages involved in synucleinopathies representing an attractive strategy to elucidate-common and specific-SNCA-genetic variants, regulatory mechanisms, and vulnerable expression levels underlying synucleinopathy spectrum disorders. This forthcoming knowledge will support the development of precision medicine for synucleinopathies.
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Affiliation(s)
- L Tagliafierro
- Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA
| | - O Chiba-Falek
- Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA.
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Brudek T, Winge K, Rasmussen NB, Bahl JMC, Tanassi J, Agander TK, Hyde TM, Pakkenberg B. Altered α-synuclein, parkin, and synphilin isoform levels in multiple system atrophy brains. J Neurochem 2015; 136:172-85. [DOI: 10.1111/jnc.13392] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 09/29/2015] [Indexed: 01/16/2023]
Affiliation(s)
- Tomasz Brudek
- Research Laboratory for Stereology and Neuroscience; Bispebjerg-Frederiksberg Hospital; University Hospital of Copenhagen; Copenhagen NV Denmark
- Bispebjerg Movement Disorders Biobank; Bispebjerg-Frederiksberg Hospital; University Hospital of Copenhagen; Copenhagen N Denmark
| | - Kristian Winge
- Department of Neurology; Bispebjerg-Frederiksberg Hospital; University Hospital of Copenhagen; Copenhagen NV Denmark
- Bispebjerg Movement Disorders Biobank; Bispebjerg-Frederiksberg Hospital; University Hospital of Copenhagen; Copenhagen N Denmark
| | - Nadja Bredo Rasmussen
- Research Laboratory for Stereology and Neuroscience; Bispebjerg-Frederiksberg Hospital; University Hospital of Copenhagen; Copenhagen NV Denmark
| | | | - Julia Tanassi
- Department of Autoimmunology and Biomarkers; Statens Serum Institut; Copenhagen S Denmark
| | | | - Thomas M. Hyde
- Lieber Institute for Brain Development; Johns Hopkins Medical Campus; Baltimore Maryland USA
- Department of Psychiatry and Behavioral Sciences; Johns Hopkins University School of Medicine; Baltimore Maryland USA
- Department of Neurology; Johns Hopkins University School of Medicine; Baltimore Maryland USA
| | - Bente Pakkenberg
- Research Laboratory for Stereology and Neuroscience; Bispebjerg-Frederiksberg Hospital; University Hospital of Copenhagen; Copenhagen NV Denmark
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Splicing: is there an alternative contribution to Parkinson's disease? Neurogenetics 2015; 16:245-63. [PMID: 25980689 PMCID: PMC4573652 DOI: 10.1007/s10048-015-0449-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/04/2015] [Indexed: 12/21/2022]
Abstract
Alternative splicing is a crucial mechanism of gene expression regulation that enormously increases the coding potential of our genome and represents an intermediate step between messenger RNA (mRNA) transcription and protein posttranslational modifications. Alternative splicing occupies a central position in the development and functions of the nervous system. Therefore, its deregulation frequently leads to several neurological human disorders. In the present review, we provide an updated overview on the impact of alternative splicing in Parkinson's disease (PD), the second most common neurodegenerative disorder worldwide. We will describe the alternative splicing of major PD-linked genes by collecting the current evidences about this intricate and not carefully explored aspect. Assessing the role of this mechanism on PD pathobiology may represent a central step toward an improved understanding of this complex disease.
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Schade S, Mollenhauer B. Biomarkers in biological fluids for dementia with Lewy bodies. ALZHEIMERS RESEARCH & THERAPY 2014; 6:72. [PMID: 25478030 PMCID: PMC4255553 DOI: 10.1186/s13195-014-0072-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dementia with Lewy bodies (DLB) has become the second most common neurodegenerative dementia due to demographic ageing. Differential diagnosis is still troublesome especially in early stages of the disease, since there is a great clinical and neuropathological overlap primarily with Alzheimer's disease and Parkinson's disease. Therefore, more specific biomarkers, not only for scientific reasons but also for clinical therapeutic decision-making, are urgently needed. In this review, we summarize the knowledge on fluid biomarkers for DLB, derived predominantly from cerebrospinal fluid. We discuss the value of well-defined markers (β-amyloid, (phosphorylated) tau, α-synuclein) as well as some promising 'upcoming' substances, which still have to be further evaluated.
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Affiliation(s)
- Sebastian Schade
- Paracelsus-Elena-Klinik, Klinikstraße 16, Kassel, D-34128, Germany ; Department of Clinical Neurophysiology, University Medical Center, Georg-August University, Robert-Koch Straße 40, Göttingen, 37075, Germany
| | - Brit Mollenhauer
- Paracelsus-Elena-Klinik, Klinikstraße 16, Kassel, D-34128, Germany ; Department of Neurosurgery, University Medical Center, Georg-August University, Robert-Koch Straße 40, Göttingen, 37075, Germany ; Department of Neuropathology, University Medical Center, Georg-August University, Robert-Koch Straße 40, Göttingen, 37075, Germany
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19
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Differential aggregation properties of alpha-synuclein isoforms. Neurobiol Aging 2014; 35:1913-9. [DOI: 10.1016/j.neurobiolaging.2014.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 01/14/2014] [Accepted: 02/10/2014] [Indexed: 01/22/2023]
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20
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Kanaan NM, Manfredsson FP. Loss of functional alpha-synuclein: a toxic event in Parkinson's disease? JOURNAL OF PARKINSONS DISEASE 2014; 2:249-67. [PMID: 23938255 PMCID: PMC4736738 DOI: 10.3233/jpd-012138] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The discovery that alpha-synuclein (α-syn) is the primary component of the neuropathological hallmarks of Parkinson's disease (PD) and the identification of α-syn mutations in numerous inherited forms of PD has positioned α-syn at the top of the list of important factors in the pathogenesis of PD. Based on the pathological accumulation of α-syn in the brains of patients, the field is currently focused on therapeutic strategies that aim to reduce or eliminate α-syn. However, recent evidence suggests α-syn is a critical protein in neuron (i.e. dopamine neurons) survival and that maintaining a certain level of biologically functional α-syn is an important consideration in targeting α-syn for therapies. Despite the widespread interest in α-syn, the normal biological functions remain elusive, but a large body of work is focused on addressing this issue. In this review, we will discuss the current evidence related to α-syn function, α-syn folding and aggregation, and α-syn's role in disease. Finally, we will propose a relatively novel hypothesis on the pathogenesis of PD that hinges upon the premises that functional α-syn is critical to cell survival and that a reduction in biologically functional α-syn, whether through aggregation or reduced expression, may lead to the neurodegeneration in PD.
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Affiliation(s)
- Nicholas M Kanaan
- Department of Translational Science & Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
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21
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Manda KM, Yedlapudi D, Korukonda S, Bojja S, Kalivendi SV. The chaperone-like activity of α-synuclein attenuates aggregation of its alternatively spliced isoform, 112-synuclein in vitro: plausible cross-talk between isoforms in protein aggregation. PLoS One 2014; 9:e98657. [PMID: 24892822 PMCID: PMC4043908 DOI: 10.1371/journal.pone.0098657] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 05/05/2014] [Indexed: 12/29/2022] Open
Abstract
Abnormal oligomerization and aggregation of α-synuclein (α-syn/WT-syn) has been shown to be a precipitating factor in the pathophysiology of Parkinson's disease (PD). Earlier observations on the induced-alternative splicing of α-syn by Parkinsonism mimetics as well as identification of region specific abnormalities in the transcript levels of 112-synclein (112-syn) in diseased subjects underscores the role of 112-syn in the pathophysiology of PD. In the present study, we sought to identify the aggregation potential of 112-syn in the presence or absence of WT-syn to predict its plausible role in protein aggregation events. Results demonstrate that unlike WT-syn, lack of 28 aa in the C-terminus results in the loss of chaperone-like activity with a concomitant gain in vulnerability to heat-induced aggregation and time-dependent fibrillation. The effects were dose and time-dependent and a significant aggregation of 112-syn was evident at as low as 45°C following 10 min of incubation. The heat-induced aggregates were found to be ill-defined structures and weakly positive towards Thioflavin-T (ThT) staining as compared to clearly distinguishable ThT positive extended fibrils resulting upon 24 h of incubation at 37°C. Further, the chaperone-like activity of WT-syn significantly attenuated heat-induced aggregation of 112-syn in a dose and time-dependent manner. On contrary, WT-syn synergistically enhanced fibrillation of 112-syn. Overall, the present findings highlight a plausible cross-talk between isoforms of α-syn and the relative abundance of these isoforms may dictate the nature and fate of protein aggregates.
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Affiliation(s)
- Krishna Madhuri Manda
- Centre for Academy of Scientific & Innovative Research, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
- Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
| | - Deepthi Yedlapudi
- Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
| | - Srikanth Korukonda
- Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
| | - Sreedhar Bojja
- Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
| | - Shasi V. Kalivendi
- Centre for Academy of Scientific & Innovative Research, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
- Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, Andhra Pradesh, India
- * E-mail:
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22
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Schmid AW, Fauvet B, Moniatte M, Lashuel HA. Alpha-synuclein post-translational modifications as potential biomarkers for Parkinson disease and other synucleinopathies. Mol Cell Proteomics 2013; 12:3543-58. [PMID: 23966418 DOI: 10.1074/mcp.r113.032730] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The development of novel therapies against neurodegenerative disorders requires the ability to detect their early, presymptomatic manifestations in order to enable treatment before irreversible cellular damage occurs. Precocious signs indicative of neurodegeneration include characteristic changes in certain protein levels, which can be used as diagnostic biomarkers when they can be detected in fluids such as blood plasma or cerebrospinal fluid. In the case of synucleinopathies, cerebrospinal alpha-synuclein (α-syn) has attracted great interest as a potential biomarker; however, there is ongoing debate regarding the association between cerebrospinal α-syn levels and neurodegeneration in Parkinson disease and synucleinopathies. Post-translational modifications (PTMs) have emerged as important determinants of α-syn's physiological and pathological functions. Several PTMs are enriched within Lewy bodies and exist at higher levels in α-synucleinopathy brains, suggesting that certain modified forms of α-syn might be more relevant biomarkers than the total α-syn levels. However, the quantification of PTMs in bodily fluids poses several challenges. This review describes the limitations of current immunoassay-based α-syn quantification methods and highlights how these limitations can be overcome using novel mass-spectrometry-based assays. In addition, we describe how advances in chemical synthesis, which have enabled the preparation of α-syn proteins that are site-specifically modified at single or multiple residues, can facilitate the development of more accurate assays for detecting and quantifying α-syn PTMs in health and disease.
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Affiliation(s)
- Adrien W Schmid
- Proteomics Core Facility, School of Life Sciences, Station 19, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Ma KL, Song LK, Long WA, Yuan YH, Zhang Y, Song XY, Niu F, Han N, Chen NH. Deletion in exon 5 of the SNCA gene and exposure to rotenone leads to oligomerization of α-synuclein and toxicity to PC12 cells. Brain Res Bull 2013; 90:127-31. [PMID: 23128054 DOI: 10.1016/j.brainresbull.2012.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 10/27/2022]
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24
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Mollenhauer B, Zhang J. Biochemical premotor biomarkers for Parkinson's disease. Mov Disord 2012; 27:644-50. [PMID: 22508282 DOI: 10.1002/mds.24956] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A biomarker is a biological characteristic that is objectively measured and evaluated as an indicator of normal biological or pathologic processes or of pharmacologic responses to a therapeutic intervention. We reviewed the current status of target protein biomarkers (eg, total/oligomeric α-synuclein and DJ-1) in cerebrospinal fluid, as well as on unbiased processes that can be used to discover novel biomarkers. We have also provide details about strategies toward potential populations/models and technologies, including the need for standardized sampling techniques, to pursue the identification of new biochemical markers in the premotor stage of Parkinson's disease in the future.
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Affiliation(s)
- Brit Mollenhauer
- Paracelsus-Elena-Klinik and Georg August University Goettingen, Kassel, Germany.
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Beyer K, Munoz-Marmol AM, Sanz C, Marginet-Flinch R, Ferrer I, Ariza A. New brain-specific beta-synuclein isoforms show expression ratio changes in Lewy body diseases. Neurogenetics 2011; 13:61-72. [PMID: 22205345 DOI: 10.1007/s10048-011-0311-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 12/15/2011] [Indexed: 12/22/2022]
Abstract
Lewy body diseases (LBDs) include dementia with Lewy bodies (DLB) and Parkinson disease (PD). Alpha-synuclein (AS) aggregation is a key event in the pathogenesis of LBDs and beta-synuclein (BS) inhibits AS aggregation in vitro and in vivo. Recently, BS has been shown to interact directly with AS regulating its functionality and preventing its oligomerization, and a molecular subgroup of pure DLB lacks BS in cortical regions. In this study, we characterized four new BS transcript variants and analyzed their expression in neuronal and non-neuronal tissue, and their differential expression in frozen samples of three areas from brains of patients with pure Lewy body pathology (LBP), common LBP, Alzheimer pathology, and of controls. Relative mRNA expression was determined by real-time PCR with neuron-specific enolase 2 and synaptophysin as housekeeping genes, and expression changes were evaluated by the ΔΔCt method. Two main findings are in concordance with earlier studies. First, all BS isoforms are drastically diminished in the cortex of patients with pure LBP that had presented clinically as DLB but not PD with dementia. Second, an important shift of the isoform expression ratio was observed in the temporal cortex of all LBD cases, and the minor isoforms, normally absent in the midbrain, were detected in the caudate nucleus of all DLB samples. Our results provide further evidence for the role of minor transcript variants in the development of complex diseases and provide new insights into the pathogenesis of LBDs that may be important for the understanding of molecular mechanisms involved in these complex diseases.
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Affiliation(s)
- Katrin Beyer
- Servicio de Anatomía Patológica, Hospital Universitario Germans Trias i Pujol, Ctra Canyet s/n, 08916, Badalona, Barcelona, Spain.
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Transcript expression levels of full-length alpha-synuclein and its three alternatively spliced variants in Parkinson's disease brain regions and in a transgenic mouse model of alpha-synuclein overexpression. Mol Cell Neurosci 2011; 49:230-9. [PMID: 22155155 DOI: 10.1016/j.mcn.2011.11.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/28/2011] [Accepted: 11/26/2011] [Indexed: 01/22/2023] Open
Abstract
Alternative splicing is a complex post-transcriptional process that can be regulated by cis-acting elements located within genomic non-coding regions. Recent studies have identified that polymorphic variations in non-coding regions of the α-synuclein gene (SNCA) locus are associated with an increased risk for developing Parkinson's disease (PD). The underlying mechanism(s) for this susceptibility may involve changes in α-synuclein mRNA expression and alternative splicing. As a first step towards understanding the biology of α-synuclein splice variants in PD, we characterized the levels of the full-length SNCA-140 mRNA transcript and SNCA-126, -112, and -98 alternatively spliced variants in different neuronal regions from PD patients or transgenic mice overexpressing human α-synuclein (ASO). In human post-mortem tissue, α-synuclein spliced transcripts were expressed in a region-specific manner in the cortex, substantia nigra, and cerebellum. We observed increased nigral SNCA-140 and SNCA-126 transcript levels in PD patients when compared to neurologically unaffected cases. Human α-synuclein splicing changes were also found to occur in a region-specific manner in ASO mice. Here, SNCA-126, -112, and -98 transcript levels did not increase proportionally with SNCA-140 levels, or parallel the region-specific mouse transcript ratios seen in wild-type (WT) littermates. While most transcripts were elevated in ASO mice when compared to WT mice, the most prominent increase was found in the ventral midbrain of 15-month-old ASO mice. These results demonstrate region-specific human α-synuclein transcript level abnormalities in PD patients and in a transgenic mouse model of α-synucleinopathy. This study is relevant to understanding the normal, adaptive, or pathological role(s) of α-synuclein splice variants.
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Muntané G, Ferrer I, Martinez-Vicente M. α-synuclein phosphorylation and truncation are normal events in the adult human brain. Neuroscience 2011; 200:106-19. [PMID: 22079575 DOI: 10.1016/j.neuroscience.2011.10.042] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 09/26/2011] [Accepted: 10/22/2011] [Indexed: 12/14/2022]
Abstract
α-synuclein is a key protein in Lewy body diseases (LBDs) and a major component of Lewy bodies and related aberrant cytoplasmic and neuritic inclusions. Regional differences in α-synuclein have been associated with selective neuronal vulnerability to Lewy pathology. Furthermore, phosphorylation at serine 129 (Ser129) and α-synuclein truncation have been considered crucial in the pathogenesis of Lewy inclusions. The present study shows consistent reduction in α-synuclein protein expression levels in the human substantia nigra and nucleus basalis of Meynert compared with other brain regions independently of age and pathology. Phosphorylated α-synuclein at Ser129 is naturally increased in these same regions, thus inversely related with the total amount of α-synuclein. In contrast, truncated α-synuclein is naturally observed in control and diseased brains and correlating with the total amount of α-synuclein. Several truncated variants have been identified where some of these variants are truncated at the C-terminal domain, whereas others are truncated at the N-terminal domain, and all are present in cases with and without Lewy pathology. Although accumulation of truncated α-synuclein variants and phosphorylated α-synuclein occurs in Lewy bodies, α-synuclein phosphorylation and truncation can be considered constitutive in control and diseased brains.
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Affiliation(s)
- G Muntané
- Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de LLobregat, CIBERNED, Instituto Carlos III, Barcelona, Spain
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28
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Beyer K, Domingo-Sàbat M, Santos C, Tolosa E, Ferrer I, Ariza A. The decrease of β-synuclein in cortical brain areas defines a molecular subgroup of dementia with Lewy bodies. ACTA ACUST UNITED AC 2010; 133:3724-33. [PMID: 20959308 DOI: 10.1093/brain/awq275] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lewy body diseases include dementia with Lewy bodies and Parkinson's disease. Whereas dementia with Lewy bodies and Parkinson's disease can be distinguished as separate clinical entities, the pathological picture is very often identical. α-synuclein aggregation is a key event in the pathogenesis of Lewy body diseases and β-synuclein inhibits α-synuclein aggregation in vitro and in vivo. Recently, β-synuclein has been shown to interact directly with α-synuclein, regulating its functionality and preventing its oligomerization. In this study, we analysed the expression of two β-synuclein transcript variants and the main α-synuclein transcript SNCA140, in frozen samples of three areas from brains of patients with (i) pure diffuse Lewy body pathology; (ii) pure Alzheimer's disease pathology; (iii) diffuse Lewy body pathology and concomitant Alzheimer's disease pathology and (iv) controls. Relative messenger RNA expression was determined by real-time polymerase chain reaction, expression changes were evaluated by the ΔΔC(t) method and messenger RNA expression data were confirmed at the protein level. A drastic diminution of β-synuclein expression was observed in cortical areas of all samples that presented neuropathological features corresponding to pure diffuse Lewy body pathology and the clinical phenotype of dementia with Lewy bodies, but not in those with neuropathological features corresponding to diffuse Lewy body pathology and concomitant Alzheimer's disease pathology or the clinical phenotype of Parkinson's disease with dementia. The correlation of expression data with the clinical phenotype and neuropathological diagnosis of the patients suggested the existence of a specific molecular subtype of dementia with Lewy bodies, characterized by a strong decrease of β-synuclein in the frontal and temporal cortices. Furthermore, our findings provide new insights into the pathogenesis of Lewy body diseases that may be important for the understanding of molecular mechanisms involved in these complex diseases.
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Affiliation(s)
- Katrin Beyer
- Servicio de Anatomía Patológica, Hospital Universitario Germans Trias i Pujol, Universidad Autonoma de Barcelona, Barcelona, Spain.
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29
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Yang ML, Hasadsri L, Woods WS, George JM. Dynamic transport and localization of alpha-synuclein in primary hippocampal neurons. Mol Neurodegener 2010; 5:9. [PMID: 20181133 PMCID: PMC2830200 DOI: 10.1186/1750-1326-5-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 02/09/2010] [Indexed: 01/15/2023] Open
Abstract
Background Alpha-synuclein is a presynaptic protein with a proposed role in neurotransmission and dopamine homeostasis. Abnormal accumulation of α-synuclein aggregates in dopaminergic neurons of the substantia nigra is diagnostic of sporadic Parkinson's disease, and mutations in the protein are linked to early onset forms of the disease. The folded conformation of the protein varies depending upon its environment and other factors that are poorly understood. When bound to phospholipid membranes, α-synuclein adopts a helical conformation that mediates specific interactions with other proteins. Results To investigate the role of the helical domain in transport and localization of α-synuclein, eGFP-tagged constructs were transfected into rat primary hippocampal neurons at 7 DIV. A series of constructs were analyzed in which each individual exon was deleted, for comparison to previous studies of lipid affinity and α-helix content. A53T and A30P substitutions, representing Parkinson's disease-associated variants, were analyzed as well. Single exon deletions within the lipid-binding N-terminal domain of α-synuclein (exons 2, 3, and 4) partially disrupted its presynaptic localization at 17-21 DIV, resulting in increased diffuse labeling of axons. Similar results were obtained for A30P, which exhibits decreased lipid binding, but not A53T. To examine whether differences in presynaptic enrichment were related to deficiencies in transport velocity, transport was visualized via live cell microscopy. Tagged α-synuclein migrated at a rate of 1.85 ± 0.09 μm/s, consistent with previous reports, and single exon deletion mutants migrated at similar rates, as did A30P. Deletion of the entire N-terminal lipid-binding domain (Δ234GFP) did not significantly alter rates of particle movement, but decreased the number of moving particles. Only the A53TGFP mutant exhibited a significant decrease in transport velocity as compared to ASGFP. Conclusions These results support the hypothesis that presynaptic localization involves a mechanism that requires helical conformation and lipid binding. Conversely, the rate of axonal transport is not determined by lipid affinity and is not sufficient to account for differences in presynaptic localization of α-synuclein-eGFP variants.
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Affiliation(s)
- Mong-Lin Yang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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Mollenhauer B, Trenkwalder C. Neurochemical biomarkers in the differential diagnosis of movement disorders. Mov Disord 2009; 24:1411-26. [PMID: 19412961 DOI: 10.1002/mds.22510] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In recent years, the neurochemical analysis of neuronal proteins in cerebrospinal fluid (CSF) has become increasingly accepted for the diagnosis of neurodegenerative dementia diseases such as Alzheimer's disease and Creutzfeldt-Jakob disease. CSF surrounds the central nervous system, and in the composition of CSF proteins one finds brain-specific proteins that are prioritized from blood-derived proteins. Levels of specific CSF proteins could be very promising biomarkers for central nervous system diseases. We need the development of more easily accessible biomarkers, in the blood. In neurodegenerative diseases with and without dementia, studies on CSF and blood proteins have investigated the usefulness of biomarkers in differential diagnosis. The clinical diagnoses of Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration still rely mainly on clinical symptoms as defined by international classification criteria. In this article, we review CSF biomarkers in these movement disorders and discuss recent published reports on the neurochemical intra vitam diagnosis of neurodegenerative disorders (including recent CSF alpha-synuclein findings).
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Molecular pathology of Lewy body diseases. Int J Mol Sci 2009; 10:724-45. [PMID: 19399218 PMCID: PMC2671999 DOI: 10.3390/ijms10030724] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/03/2009] [Accepted: 02/23/2009] [Indexed: 11/16/2022] Open
Abstract
Lewy body diseases are characterized by the presence of Lewy bodies, alpha-synuclein(AS)-positive inclusions in the brain. Since their main component is conformationally modified AS, aggregation of the latter is thought to be a key pathogenic event in these diseases. The analysis of inclusion body constituents gives additional information about pathways also involved in the pathology of synucleinopathies. Widespread mitochondrial dysfunction is very closely related to disease development. The impairment of protein degradation pathways, including both the ubiquitin-proteasome system and the autophagy-lysosome pathway also play an important role during the development of Lewy body diseases. Finally, differential expression changes of isoforms corresponding to genes primarily involved in Lewy body formation point to alternative splicing as another important mechanism in the development of Parkinson’s disease, as well as dementia with Lewy bodies. The present paper attempts to give an overview of recent molecular findings related to the pathogenesis of Lewy body diseases.
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Beyer K, Domingo-Sàbat M, Humbert J, Carrato C, Ferrer I, Ariza A. Differential expression of alpha-synuclein, parkin, and synphilin-1 isoforms in Lewy body disease. Neurogenetics 2008; 9:163-72. [PMID: 18335262 DOI: 10.1007/s10048-008-0124-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 02/19/2008] [Indexed: 12/18/2022]
Abstract
Alpha-synuclein, parkin, and synphilin-1 are proteins mainly involved in the pathogenesis of Lewy body (LB) diseases. mRNAs of all three undergo alternative splicing, so that the existence of various isoforms has been described. Since increasing evidence supports the importance of differential isoform-expression changes in disease development, we have established isoform-expression profiles in frontal cortices of LB disease brains in comparison with those of Alzheimer disease (AD) and control frontal cortices. The differential expression of four alpha-synuclein, seven parkin, and four synphilin-1 isoforms was ascertained by the use of isoform-specific primers and relative expression analysis with SybrGreen and beta-actin as an internal standard. The establishment of isoform-expression profiles revealed that these are disease specific. Moreover, isoform-expression deregulation of mainly one gene in each disease could be observed. All four alpha-synuclein isoforms were affected in the case of the pure form of dementia with LB, most parkin transcript variants in common LB disease, and all synphilin-1 isoforms in Parkinson disease. Only minor involvement was detected in AD. Finally, the existence of a proprietary isoform-expression profile in common LB disease indicates that this disease develops as a result of its own molecular mechanisms, and so, at the molecular level, it does not exactly share changes found in pure dementia with LB and AD. In conclusion, isoform-expression profiles in LB diseases represent additional evidence for the direct involvement of isoform-expression deregulation in the development of neurodegenerative disorders.
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Affiliation(s)
- Katrin Beyer
- Department of Pathology, Hospital Germans Trias i Pujol, Autonomous University of Barcelona, Barcelona, Spain.
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Gründemann J, Schlaudraff F, Haeckel O, Liss B. Elevated alpha-synuclein mRNA levels in individual UV-laser-microdissected dopaminergic substantia nigra neurons in idiopathic Parkinson's disease. Nucleic Acids Res 2008; 36:e38. [PMID: 18332041 PMCID: PMC2367701 DOI: 10.1093/nar/gkn084] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The presynaptic protein α-synuclein is involved in several neurodegenerative diseases, including Parkinson's disease (PD). In rare familial forms of PD, causal mutations (PARK1) as well as multiplications (PARK4) of the α-synuclein gene have been identified. In sporadic, idiopathic PD, abnormal accumulation and deposition of α-synuclein might also cause degeneration of dopaminergic midbrain neurons, the clinically most relevant neuronal population in PD. Thus, cell-specific quantification of α-synuclein expression-levels in dopaminergic neurons from idiopathic PD patients in comparison to controls would provide essential information about contributions of α-synuclein to the etiology of PD. However, a number of previous studies addressing this question at the tissue-level yielded varying results regarding α-synuclein expression. To increase specificity, we developed a cell-specific approach for mRNA quantification that also took into account the important issue of variable RNA integrities of the individual human postmortem brain samples. We demonstrate that PCR –amplicon size can confound quantitative gene-expression analysis, in particular of partly degraded RNA. By combining optimized UV-laser microdissection- and quantitative RT–PCR-techniques with suitable PCR assays, we detected significantly elevated α-synuclein mRNA levels in individual, surviving neuromelanin- and tyrosine hydroxylase-positive substantia nigra dopaminergic neurons from idiopathic PD brains compared to controls. These results strengthen the pathophysiologic role of transcriptional dysregulation of the α-synuclein gene in sporadic PD.
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Affiliation(s)
- Jan Gründemann
- Molecular Neurobiology, Department of Physiology, Philipps-University Marburg, Deutschhausstrasse 2, 35037 Marburg, Germany
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Beyer K, Domingo-Sábat M, Lao JI, Carrato C, Ferrer I, Ariza A. Identification and characterization of a new alpha-synuclein isoform and its role in Lewy body diseases. Neurogenetics 2007; 9:15-23. [PMID: 17955272 DOI: 10.1007/s10048-007-0106-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2007] [Accepted: 09/27/2007] [Indexed: 01/13/2023]
Abstract
Alternative splicing is an important mechanism to generate a large number of mRNAs, thus increasing proteome diversity and tissue specificity. Three transcript variants of alpha-synuclein, a neuronal protein mainly involved in synapses, have been described so far. Whereas alpha-synuclein 140 is the whole and main transcript, alpha-synuclein 112 and 126 are short proteins that result from in-frame deletions of exons 3 and 5, respectively. Because the aforesaid alpha-synuclein isoforms show differential expression changes in Lewy body diseases (LBDs), in the present work, we searched for a fourth alpha-synuclein isoform and studied its expression levels in LBD brains. By using isoform-specific primers, isoform co-amplification and direct sequencing, we identified alpha-synuclein 98, which lacks exons 3 and 5. mRNA expression analyses in non-neuronal tissue revealed that alpha-synuclein 98 is a brain-specific splice variant with varying expression levels in different areas of fetal and adult brain. Additionally, we studied alpha-synuclein 98 expression levels by real-time semi-quantitative RT-PCR in the frontal cortices of LBD patients and compared them with those of Alzheimer disease (AD) patients and control subjects. Overexpression of alpha-synuclein 98 in LBD and AD brains would indicate its specific involvement in the pathogenesis of these neurodegenerative disorders.
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Affiliation(s)
- Katrin Beyer
- Department of Pathology, Hospital Universitari Germans Trias i Pujol, Autonomous University of Barcelona, Barcelona, Spain.
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Beyer K, Humbert J, Ferrer A, Lao JI, Latorre P, Lopez D, Tolosa E, Ferrer I, Ariza A. A variable poly-T sequence modulates alpha-synuclein isoform expression and is associated with aging. J Neurosci Res 2007; 85:1538-46. [PMID: 17387688 DOI: 10.1002/jnr.21270] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
alpha-Synuclein, the main component of proteinaceous inclusions in synucleinopathies, is centrally involved in aggregation processes preceding Lewy body formation. Here we describe a new alpha-synuclein gene poly-T polymorphism that is situated upstream to exon 3 and consists of three different alleles. A correlation between poly-T length and expression of alpha-synuclein 126 mRNA, an isoform lacking exon 3, was detected in the human cerebral cortex. Specifically, when compared with the most frequent 7T/7T genotype, the shortest poly-T stretch (5T) was associated with the lowest alpha-synuclein 126 expression levels, whereas the longest poly-T stretch (12T) was accompanied by the highest alpha-synuclein 126 expression levels. Thus, three different expression-level-specific genotypes, with 5T+ genotypes as low alpha-synuclein 126 expression genotypes and 12T+ genotypes as high alpha-synuclein 126 expression genotypes, could be established. Poly-T genotype distributions were also analyzed in a healthy control population. Age-dependent variations in this distribution were observed and showed accumulation of low alpha-synuclein 126 expression genotypes at ages under 60 years and high alpha-synuclein 126 expression genotypes at ages over 80 years. To determine human specificity of the variable poly-T strech, the mouse alpha-synuclein gene sequence was analyzed. Although alpha-synuclein is very well conserved in vertebrates, the poly-T sequence was found to be absent in mice, and an alpha-synuclein 126 mouse homologue could not be detected. In conclusion, this newly identified poly-T polymorphism is a human-specific sequence; its length influences alpha-synuclein 126 expression levels; and, finally, it seems to exert a specific influence on normal aging.
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Affiliation(s)
- Katrin Beyer
- Department of Pathology, Hospital Germans Trias i Pujol, Autonomous University of Barcelona, Badalona, Spain.
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Humbert J, Beyer K, Carrato C, Mate JL, Ferrer I, Ariza A. Parkin and synphilin-1 isoform expression changes in Lewy body diseases. Neurobiol Dis 2007; 26:681-7. [PMID: 17467279 DOI: 10.1016/j.nbd.2007.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 03/19/2007] [Indexed: 11/24/2022] Open
Abstract
Alternative splicing gives rise to at least seven parkin and eight synphilin-1 isoforms. Since both parkin and synphilin-1 have been involved in Lewy body (LB) formation, we decided to explore whether their isoforms are differentially expressed in LB diseases. With this aim, we studied relative mRNA expression levels of parkin and synphilin-1 isoforms in the frontal cortices of patients with dementia with LBs, the LB variant of Alzheimer's disease and Parkinson's disease and compared the findings with those obtained from Alzheimer's disease patients and control individuals. Duplex real-time PCR reactions, with beta-actin as internal standard, were carried out in a LightCycler. mRNA expression levels of parkin and synphilin-1 isoforms were seen to be specifically altered in each of the LB diseases studied. These findings suggest that parkin and synphilin-1 isoform expression changes play a significant role in the pathogenesis of LB diseases.
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Affiliation(s)
- Jordi Humbert
- Departments of Pathology, Hospital Germans Trias i Pujol, Autonomous University of Barcelona, 08916 Badalona, Spain
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Beyer K. Alpha-synuclein structure, posttranslational modification and alternative splicing as aggregation enhancers. Acta Neuropathol 2006; 112:237-51. [PMID: 16845533 DOI: 10.1007/s00401-006-0104-6] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2006] [Revised: 06/20/2006] [Accepted: 06/21/2006] [Indexed: 11/26/2022]
Abstract
Alpha-synuclein aggregation is thought to be a key event in the pathogenesis of synucleinopathies. Although different alpha-synuclein alterations and modifications have been proposed to be responsible for early aggregation steps, the mechanisms underlying these events remain unclarified. Alpha-synuclein is a small protein localized to synaptic terminals and its intrinsic structure has been claimed to be an important factor for self-oligomerization and self-aggregation. Alpha-synuclein expression studies in cell cultures have demonstrated that posttranslational modifications, such as phosphorylation, oxidation, and sumoylation, are primarily involved in alpha-synuclein aggregation. Furthermore, in the last few years accumulating evidence has pointed to alternative splicing as a crucial mechanism in the development of neurodegenerative disorders. At least three different alpha-synuclein isoforms have been described as products of alternative splicing. Two of these isoforms (alpha-synuclein 112 and alpha-synuclein 126) are shorter proteins with probably altered functions and aggregation propensity. The present review attempts to summarize the data so far available on alpha-synuclein structure, posttranslational modifications, and alternative splicing as possible enhancers of aggregation.
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Affiliation(s)
- Katrin Beyer
- Department of Pathology, Hospital Universitari Germans Trias i Pujol, Autonomous University of Barcelona, 08916 Badalona, Barcelona, Spain.
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