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Miao Y, Meng H. The involvement of α-synucleinopathy in the disruption of microglial homeostasis contributes to the pathogenesis of Parkinson's disease. Cell Commun Signal 2024; 22:31. [PMID: 38216911 PMCID: PMC10785555 DOI: 10.1186/s12964-023-01402-y] [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: 07/21/2023] [Accepted: 11/18/2023] [Indexed: 01/14/2024] Open
Abstract
The intracellular deposition and intercellular transmission of α-synuclein (α-syn) are shared pathological characteristics among neurodegenerative disorders collectively known as α-synucleinopathies, including Parkinson's disease (PD). Although the precise triggers of α-synucleinopathies remain unclear, recent findings indicate that disruption of microglial homeostasis contributes to the pathogenesis of PD. Microglia play a crucial role in maintaining optimal neuronal function by ensuring a homeostatic environment, but this function is disrupted during the progression of α-syn pathology. The involvement of microglia in the accumulation, uptake, and clearance of aggregated proteins is critical for managing disease spread and progression caused by α-syn pathology. This review summarizes current knowledge on the interrelationships between microglia and α-synucleinopathies, focusing on the remarkable ability of microglia to recognize and internalize extracellular α-syn through diverse pathways. Microglia process α-syn intracellularly and intercellularly to facilitate the α-syn neuronal aggregation and cell-to-cell propagation. The conformational state of α-synuclein distinctly influences microglial inflammation, which can affect peripheral immune cells such as macrophages and lymphocytes and may regulate the pathogenesis of α-synucleinopathies. We also discuss ongoing research efforts to identify potential therapeutic approaches targeting both α-syn accumulation and inflammation in PD. Video Abstract.
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Affiliation(s)
- Yongzhen Miao
- Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, China
| | - Hongrui Meng
- Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, China.
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
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Subkhangulova A, Gonzalez-Lozano MA, Groffen AJA, van Weering JRT, Smit AB, Toonen RF, Verhage M. Tomosyn affects dense core vesicle composition but not exocytosis in mammalian neurons. eLife 2023; 12:e85561. [PMID: 37695731 PMCID: PMC10495110 DOI: 10.7554/elife.85561] [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: 12/13/2022] [Accepted: 08/28/2023] [Indexed: 09/13/2023] Open
Abstract
Tomosyn is a large, non-canonical SNARE protein proposed to act as an inhibitor of SNARE complex formation in the exocytosis of secretory vesicles. In the brain, tomosyn inhibits the fusion of synaptic vesicles (SVs), whereas its role in the fusion of neuropeptide-containing dense core vesicles (DCVs) is unknown. Here, we addressed this question using a new mouse model with a conditional deletion of tomosyn (Stxbp5) and its paralogue tomosyn-2 (Stxbp5l). We monitored DCV exocytosis at single vesicle resolution in tomosyn-deficient primary neurons using a validated pHluorin-based assay. Surprisingly, loss of tomosyns did not affect the number of DCV fusion events but resulted in a strong reduction of intracellular levels of DCV cargos, such as neuropeptide Y (NPY) and brain-derived neurotrophic factor (BDNF). BDNF levels were largely restored by re-expression of tomosyn but not by inhibition of lysosomal proteolysis. Tomosyn's SNARE domain was dispensable for the rescue. The size of the trans-Golgi network and DCVs was decreased, and the speed of DCV cargo flux through Golgi was increased in tomosyn-deficient neurons, suggesting a role for tomosyns in DCV biogenesis. Additionally, tomosyn-deficient neurons showed impaired mRNA expression of some DCV cargos, which was not restored by re-expression of tomosyn and was also observed in Cre-expressing wild-type neurons not carrying loxP sites, suggesting a direct effect of Cre recombinase on neuronal transcription. Taken together, our findings argue against an inhibitory role of tomosyns in neuronal DCV exocytosis and suggests an evolutionary conserved function of tomosyns in the packaging of secretory cargo at the Golgi.
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Affiliation(s)
- Aygul Subkhangulova
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) AmsterdamAmsterdamNetherlands
| | - Miguel A Gonzalez-Lozano
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) AmsterdamAmsterdamNetherlands
| | - Alexander JA Groffen
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam University Medical Center (UMC)AmsterdamNetherlands
| | - Jan RT van Weering
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam University Medical Center (UMC)AmsterdamNetherlands
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) AmsterdamAmsterdamNetherlands
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) AmsterdamAmsterdamNetherlands
| | - Matthijs Verhage
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) AmsterdamAmsterdamNetherlands
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam University Medical Center (UMC)AmsterdamNetherlands
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Thanou E, Koopmans F, Pita-Illobre D, Klaassen RV, Özer B, Charalampopoulos I, Smit AB, Li KW. Suspension TRAPping Filter (sTRAP) Sample Preparation for Quantitative Proteomics in the Low µg Input Range Using a Plasmid DNA Micro-Spin Column: Analysis of the Hippocampus from the 5xFAD Alzheimer's Disease Mouse Model. Cells 2023; 12:cells12091242. [PMID: 37174641 PMCID: PMC10177283 DOI: 10.3390/cells12091242] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023] Open
Abstract
Suspension TRAPping filter (sTRAP) is an attractive sample preparation method for proteomics studies. The sTRAP protocol uses 5% SDS that maximizes protein solubilization. Proteins are trapped on a borosilicate glass membrane filter, where SDS is subsequently removed from the filter. After trypsin digestion, peptides are analyzed directly by LC-MS. Here, we demonstrated the use of a low-cost plasmid DNA micro-spin column for the sTRAP sample preparation of a dilution series of a synapse-enriched sample with a range of 10-0.3 µg. With 120 ng tryptic peptides loaded onto the Evosep LC system coupled to timsTOF Pro 2 mass spectrometer, we identified 5700 protein groups with 4% coefficient of variation (CoV). Comparing other sample preparation protocols, such as the in-gel digestion and the commercial Protifi S-TRAP with the plasmid DNA micro-spin column, the last is superior in both protein and peptide identification numbers and CoV. We applied sTRAP for the analysis of the hippocampal proteome from the 5xFAD mouse model of Alzheimer's disease and their wildtype littermates, and revealed 121 up- and 54 down-regulated proteins. Protein changes in the mutant mice point to the alteration of processes related to the immune system and Amyloid aggregation, which correlates well with the known major Alzheimer's-disease-related pathology. Data are available via ProteomeXchange with the identifier PXD041045.
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Affiliation(s)
- Evangelia Thanou
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Frank Koopmans
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Débora Pita-Illobre
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Remco V Klaassen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Berna Özer
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Ioannis Charalampopoulos
- Pharmacology Department, Faculty of Medicine, University of Crete, 71003 Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, 71003 Heraklion, Greece
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Ka Wan Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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The Interplay between α-Synuclein and Microglia in α-Synucleinopathies. Int J Mol Sci 2023; 24:ijms24032477. [PMID: 36768798 PMCID: PMC9916729 DOI: 10.3390/ijms24032477] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/19/2023] [Accepted: 01/24/2023] [Indexed: 02/01/2023] Open
Abstract
Synucleinopathies are a set of devastating neurodegenerative diseases that share a pathologic accumulation of the protein α-synuclein (α-syn). This accumulation causes neuronal death resulting in irreversible dementia, deteriorating motor symptoms, and devastating cognitive decline. While the etiology of these conditions remains largely unknown, microglia, the resident immune cells of the central nervous system (CNS), have been consistently implicated in the pathogenesis of synucleinopathies. Microglia are generally believed to be neuroprotective in the early stages of α-syn accumulation and contribute to further neurodegeneration in chronic disease states. While the molecular mechanisms by which microglia achieve this role are still being investigated, here we highlight the major findings to date. In this review, we describe how structural varieties of inherently disordered α-syn result in varied microglial receptor-mediated interactions. We also summarize which microglial receptors enable cellular recognition and uptake of α-syn. Lastly, we review the downstream effects of α-syn processing within microglia, including spread to other brain regions resulting in neuroinflammation and neurodegeneration in chronic disease states. Understanding the mechanism of microglial interactions with α-syn is vital to conceptualizing molecular targets for novel therapeutic interventions. In addition, given the significant diversity in the pathophysiology of synucleinopathies, such molecular interactions are vital in gauging all potential pathways of neurodegeneration in the disease state.
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Cox WR, Faliagkas L, Besseling A, van der Loo RJ, Spijker S, Kindt M, Rao-Ruiz P. Interfering With Contextual Fear Memories by Post-reactivation Administration of Propranolol in Mice: A Series of Null Findings. Front Behav Neurosci 2022; 16:893572. [PMID: 35832291 PMCID: PMC9272000 DOI: 10.3389/fnbeh.2022.893572] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Post-reactivation amnesia of contextual fear memories by blockade of noradrenergic signaling has been shown to have limited replicability in rodents. This is usually attributed to several boundary conditions that gate the destabilization of memory during its retrieval. How these boundary conditions can be overcome, and what neural mechanisms underlie post-reactivation changes in contextual fear memories remain largely unknown. Here, we report a series of experiments in a contextual fear-conditioning paradigm in mice, that were aimed at solving these issues. We first attempted to obtain a training paradigm that would consistently result in contextual fear memory that could be destabilized upon reactivation, enabling post-retrieval amnesia by the administration of propranolol. Unexpectedly, our attempts were unsuccessful to this end. Specifically, over a series of experiments in which we varied different parameters of the fear acquisition procedure, at best small and inconsistent effects were observed. Additionally, we found that propranolol did not alter retrieval-induced neural activity, as measured by the number of c-Fos+ cells in the hippocampal dentate gyrus. To determine whether propranolol was perhaps ineffective in interfering with reactivated contextual fear memories, we also included anisomycin (i.e., a potent and well-known amnesic drug) in several experiments, and measures of synaptic glutamate receptor subunit GluA2 (i.e., a marker of memory destabilization). No post-retrieval amnesia by anisomycin and no altered GluA2 expression by reactivation was observed, suggesting that the memories did not undergo destabilization. The null findings are surprising, given that the training paradigms we implemented were previously shown to result in memories that could be modified upon reactivation. Together, our observations illustrate the elusive nature of reactivation-dependent changes in non-human fear memory.
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Affiliation(s)
- Wouter R. Cox
- Department of Psychology, Clinical Psychology, University of Amsterdam, Amsterdam, Netherlands
| | - Leonidas Faliagkas
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Amber Besseling
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Rolinka J. van der Loo
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Sabine Spijker
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Merel Kindt
- Department of Psychology, Clinical Psychology, University of Amsterdam, Amsterdam, Netherlands
| | - Priyanka Rao-Ruiz
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- *Correspondence: Priyanka Rao-Ruiz
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