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Ng XY, Cao M. Dysfunction of synaptic endocytic trafficking in Parkinson's disease. Neural Regen Res 2024; 19:2649-2660. [PMID: 38595283 PMCID: PMC11168511 DOI: 10.4103/nrr.nrr-d-23-01624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/12/2023] [Accepted: 01/03/2024] [Indexed: 04/11/2024] Open
Abstract
Parkinson's disease is characterized by the selective degeneration of dopamine neurons in the nigrostriatal pathway and dopamine deficiency in the striatum. The precise reasons behind the specific degeneration of these dopamine neurons remain largely elusive. Genetic investigations have identified over 20 causative PARK genes and 90 genomic risk loci associated with both familial and sporadic Parkinson's disease. Notably, several of these genes are linked to the synaptic vesicle recycling process, particularly the clathrin-mediated endocytosis pathway. This suggests that impaired synaptic vesicle recycling might represent an early feature of Parkinson's disease, followed by axonal degeneration and the eventual loss of dopamine cell bodies in the midbrain via a "dying back" mechanism. Recently, several new animal and cellular models with Parkinson's disease-linked mutations affecting the endocytic pathway have been created and extensively characterized. These models faithfully recapitulate certain Parkinson's disease-like features at the animal, circuit, and cellular levels, and exhibit defects in synaptic membrane trafficking, further supporting the findings from human genetics and clinical studies. In this review, we will first summarize the cellular and molecular findings from the models of two Parkinson's disease-linked clathrin uncoating proteins: auxilin (DNAJC6/PARK19) and synaptojanin 1 (SYNJ1/PARK20). The mouse models carrying these two PARK gene mutations phenocopy each other with specific dopamine terminal pathology and display a potent synergistic effect. Subsequently, we will delve into the involvement of several clathrin-mediated endocytosis-related proteins (GAK, endophilin A1, SAC2/INPP5F, synaptotagmin-11), identified as Parkinson's disease risk factors through genome-wide association studies, in Parkinson's disease pathogenesis. We will also explore the direct or indirect roles of some common Parkinson's disease-linked proteins (alpha-synuclein (PARK1/4), Parkin (PARK2), and LRRK2 (PARK8)) in synaptic endocytic trafficking. Additionally, we will discuss the emerging novel functions of these endocytic proteins in downstream membrane traffic pathways, particularly autophagy. Given that synaptic dysfunction is considered as an early event in Parkinson's disease, a deeper understanding of the cellular mechanisms underlying synaptic vesicle endocytic trafficking may unveil novel targets for early diagnosis and the development of interventional therapies for Parkinson's disease. Future research should aim to elucidate why generalized synaptic endocytic dysfunction leads to the selective degeneration of nigrostriatal dopamine neurons in Parkinson's disease.
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Affiliation(s)
- Xin Yi Ng
- Programme in Neuroscience and Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Mian Cao
- Programme in Neuroscience and Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore
- Department of Physiology, National University of Singapore, Singapore, Singapore
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2
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Senkevich K, Parlar SC, Chantereault C, Yu E, Ahmad J, Ruskey JA, Asayesh F, Spiegelman D, Waters C, Monchi O, Dauvilliers Y, Dupré N, Miliukhina I, Timofeeva A, Emelyanov A, Pchelina S, Greenbaum L, Hassin-Baer S, Alcalay RN, Gan-Or Z. Are rare heterozygous SYNJ1 variants associated with Parkinson's disease? MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.29.24307986. [PMID: 38853950 PMCID: PMC11160829 DOI: 10.1101/2024.05.29.24307986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Previous studies have suggested that rare biallelic SYNJ1 mutations may cause autosomal recessive parkinsonism and Parkinson's disease (PD). Our study explored the impact of rare SYNJ1 variants in non-familial settings, including 8,165 PD cases, 818 early-onset PD (EOPD, <50 years) and 70,363 controls. Burden meta-analysis using optimized sequence Kernel association test (SKAT-O) revealed an association between rare nonsynonymous variants in the Sac1 SYNJ1 domain and PD (Pfdr=0.040). Additionally, a meta-analysis focusing on patients with EOPD demonstrated an association between all rare SYNJ1 variants and PD (Pfdr=0.029). Rare SYNJ1 variants may be associated with sporadic PD, and more specifically with EOPD.
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Affiliation(s)
- Konstantin Senkevich
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Neurology and neurosurgery, McGill University, Montréal, QC, Canada, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
| | - Sitki Cem Parlar
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
| | - Cloe Chantereault
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
| | - Eric Yu
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
| | - Jamil Ahmad
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Neurology and neurosurgery, McGill University, Montréal, QC, Canada, Canada
| | - Jennifer A. Ruskey
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Neurology and neurosurgery, McGill University, Montréal, QC, Canada, Canada
| | - Farnaz Asayesh
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
| | - Dan Spiegelman
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
| | - Cheryl Waters
- Department of Neurology, College of Physicians and Surgeons, Columbia University Medical Center, NY, USA
| | - Oury Monchi
- Department of Neurology and neurosurgery, McGill University, Montréal, QC, Canada, Canada
- Département de radiologie, radio-oncologie et médecine nucléaire, Université de Montréal, Montréal, QC, Canada
- Centre de recherche de l’Institut universitaire de gériatrie de Montréal, Montréal, QC, Canada
| | - Yves Dauvilliers
- National Reference Center for Narcolepsy, Sleep Unit, Department of Neurology, Guide-Chauliac Hospital, CHU Montpellier, University of Montpellier, Montpellier, France
| | - Nicolas Dupré
- Neuroscience axis, CHU de Québec-Université Laval, Québec, QC, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
| | | | - Alla Timofeeva
- First Pavlov State Medical University of St. Petersburg, Saint-Petersburg, Russia
| | - Anton Emelyanov
- First Pavlov State Medical University of St. Petersburg, Saint-Petersburg, Russia
| | - Sofya Pchelina
- First Pavlov State Medical University of St. Petersburg, Saint-Petersburg, Russia
| | - Lior Greenbaum
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, Israel
| | - Sharon Hassin-Baer
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, Israel
- The Movement Disorders Institute, Department of Neurology, Sheba Medical Center, Tel Hashomer, Israel
| | - Roy N. Alcalay
- Department of Neurology, College of Physicians and Surgeons, Columbia University Medical Center, NY, USA
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Division of Movement Disorders, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Ziv Gan-Or
- The Neuro (Montreal Neurological Institute-Hospital), McGill University, Montreal, Quebec, Canada
- Department of Neurology and neurosurgery, McGill University, Montréal, QC, Canada, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
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3
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Cotrin JC, Piergiorge RM, Gonçalves AP, Pereira JS, Gerber AL, de Campos Guimarães AP, de Vasconcelos ATR, Santos-Rebouças CB. Co-occurrence of PRKN and SYNJ1 variants in Early-Onset Parkinson's disease. Metab Brain Dis 2024; 39:915-928. [PMID: 38836947 DOI: 10.1007/s11011-024-01362-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 05/24/2024] [Indexed: 06/06/2024]
Abstract
Parkinson's disease (PD) is the second most prevalent neurodegenerative disease globally, with a fast-growing prevalence. The etiology of PD exhibits a multifactorial complex nature and remains challenging. Herein, we described clinical, molecular, and integrative bioinformatics findings from a Brazilian female affected by Early-Onset PD (EOPD) harboring a recurrent homozygous pathogenic deletion in the parkin RBR E3 ubiquitin protein ligase gene (PRKN; NM_004562.3:c.155delA; p.Asn52Metfs*29; rs754809877), along with a novel heterozygous variant in the synaptojanin 1 gene (SYNJ1; NM_003895.3:c.62G > T; p.Cys21Phe; rs1486511197) found by Whole Exome Sequencing. Uncommon or unreported PRKN-related clinical features in the patient include cognitive decline, auditory and visual hallucinations, REM sleep disorder, and depression, previously observed in SYNJ1-related conditions. Moreover, PRKN interacts with endophilin A1, which is a major binding partner of SYNJ1. This protein plays a pivotal role in regulating the dynamics of synaptic vesicles, particularly in the context of endocytosis and recycling processes. Altogether, our comprehensive analyses underscore a potential synergistic effect between the PRKN and SYNJ1 variants over the pathogenesis of EOPD.
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Affiliation(s)
- Juliana Cordovil Cotrin
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University, Rua São Francisco Xavier, 524, PHLC - sala 501F, Maracanã, Rio de Janeiro, RJ, 20550-013, Brazil
| | - Rafael Mina Piergiorge
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University, Rua São Francisco Xavier, 524, PHLC - sala 501F, Maracanã, Rio de Janeiro, RJ, 20550-013, Brazil
| | - Andressa Pereira Gonçalves
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University, Rua São Francisco Xavier, 524, PHLC - sala 501F, Maracanã, Rio de Janeiro, RJ, 20550-013, Brazil
| | - João Santos Pereira
- Movement Disorders Section, Neurology Service, Pedro Ernesto University Hospital, Rio de Janeiro State University, Rio de Janeiro, Brazil
| | - Alexandra Lehmkuhl Gerber
- Bioinformatics Laboratory (LABINFO), National Laboratory for Scientific Computing (LNCC), Petrópolis, Brazil
| | | | | | - Cíntia Barros Santos-Rebouças
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University, Rua São Francisco Xavier, 524, PHLC - sala 501F, Maracanã, Rio de Janeiro, RJ, 20550-013, Brazil.
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4
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Song DY, Yuan L, Cui N, Feng C, Meng L, Wang XH, Xiang M, Liu D, Wang C, Zhang Z, Li JY, Li W. α-Synuclein induces deficiency in clathrin-mediated endocytosis through inhibiting synaptojanin1 expression. J Neurochem 2023; 167:461-484. [PMID: 37788328 DOI: 10.1111/jnc.15974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/13/2023] [Accepted: 09/13/2023] [Indexed: 10/05/2023]
Abstract
Parkinson's disease (PD) is an age-related chronic neurological disorder, mainly characterized by the pathological feature of α-synuclein (α-syn) aggregation, with the exact disease pathogenesis unclear. During the onset and progression of PD, synaptic dysfunction, including dysregulation of axonal transport, impaired exocytosis, and endocytosis are identified as crucial events of PD pathogenesis. It has been reported that over-expression of α-syn impairs clathrin-mediated endocytosis (CME) in the synapses. However, the underlying mechanisms still needs to be explored. In this study, we investigated the molecular events underlying the synaptic dysfunction caused by over-expression of wild-type human α-syn and its mutant form, involving series of proteins participating in CME. We found that excessive human α-syn causes impaired fission and uncoating of clathrin-coated vesicles during synaptic vesicle recycling, leading to reduced clustering of synaptic vesicles near the active zone and increased size of plasma membrane and number of endocytic intermediates. Furthermore, over-expressed human α-syn induced changes of CME-associated proteins, among which synaptojanin1 (SYNJ1) showed significant reduction in various brain regions. Over-expression of SYNJ1 in primary hippocampal neurons from α-syn transgenic mice recovered the synaptic vesicle density, clustering and endocytosis. Using fluorescence-conjugated transferrin, we demonstrated that SYNJ1 re-boosted the CME activity by restoring the phosphatidylinositol-4,5-bisphosphate homeostasis. Our data suggested that over-expression of α-syn disrupts synaptic function through interfering with vesicle recycling, which could be alleviated by re-availing of SYNJ1. Our study unrevealed a molecular mechanism of the synaptic dysfunction in PD pathogenesis and provided a potential therapeutic target for treating PD.
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Affiliation(s)
- Dong-Yan Song
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Lin Yuan
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Na Cui
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Cong Feng
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Lanxia Meng
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xin-He Wang
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Man Xiang
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Di Liu
- Institute of Neuroscience, College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Chun Wang
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Jia-Yi Li
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
- Neural Plasticity and Repair Unit, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Wen Li
- Laboratory of Research in Parkinson's Disease and Related Disorders, Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
- Neural Plasticity and Repair Unit, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
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5
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Tian Y, Yi S, Guo W, Feng C, Zhang X, Dong H, Wang K, Li R, Tian Y, Gan M, Wu T, Xie H, Gao X. SYNJ1 rescues motor functions in hereditary and sporadic Parkinson's disease mice by upregulating TSP-1 expression. Behav Brain Res 2023; 452:114569. [PMID: 37419331 DOI: 10.1016/j.bbr.2023.114569] [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: 03/28/2023] [Revised: 06/19/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023]
Abstract
This study aimed to explore the role of SYNJ1 in Parkinson's disease (PD) and its potential as a neuroprotective factor. We found that SYNJ1 was decreased in the SN and striatum of hSNCA*A53T-Tg and MPTP-induced mice compared to normal mice, associated with motor dysfunction, increased α-synuclein and decreased tyrosine hydroxylase. To investigate its neuroprotective effects, SYNJ1 expression was upregulated in the striatum of mice through injection of the rAdV-Synj1 virus into the striatum, which resulted in the rescue of behavioral deficiencies and amelioration of pathological changes. Subsequently, transcriptomic sequencing, bioinformatics analysis and qPCR were conducted in SH-SY5Y cells following SYNJ1 gene knockdown to identify its downstream pathways, which revealed decreased expression of TSP-1 involving extracellular matrix pathways. The virtual protein-protein docking further suggested a potential interaction between the SYNJ1 and TSP-1 proteins. This was followed by the identification of a SYNJ1-dependent TSP-1 expression model in two PD models. The coimmunoprecipitation experiment verified that the interaction between SYNJ1 and TSP-1 was attenuated in 11-month-old hSNCA*A53T-Tg mice compared to normal controls. Our findings suggest that overexpression of SYNJ1 may protect hSNCA*A53T-Tg and MPTP-induced mice by upregulating TSP-1 expression, which is involved in the extracellular matrix pathways. This suggests that SYNJ1 could be a potential therapeutic target for PD, though more research is needed to understand its mechanism.
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Affiliation(s)
- Yueqin Tian
- Department of Neurology, Zhujiang Hospital, Southern Medical University, No. 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Shang Yi
- Department of Neurology, Zhujiang Hospital, Southern Medical University, No. 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Wanyun Guo
- Department of Pediatric Neurology, Zhujiang Hospital, Southern Medical University, 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Cuilian Feng
- Department of Pediatric Neurology, Zhujiang Hospital, Southern Medical University, 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Xiufen Zhang
- Department of Pediatric Neurology, Zhujiang Hospital, Southern Medical University, 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Huateng Dong
- Department of Pediatric Neurology, Zhujiang Hospital, Southern Medical University, 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Kaitao Wang
- Department of Neurology, Zhujiang Hospital, Southern Medical University, No. 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Runtong Li
- Department of Neurology, Zhujiang Hospital, Southern Medical University, No. 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China
| | - Yuanxin Tian
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, PR China
| | - Min Gan
- Department of Pediatric Neurology, Zhujiang Hospital, Southern Medical University, 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China.
| | - Ting Wu
- NMPA Key Laboratory for Research and Evaluation of Drug Metabolism & Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, PR China.
| | - Haiting Xie
- Department of Neurology, Zhujiang Hospital, Southern Medical University, No. 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China.
| | - Xiaoya Gao
- Department of Neurology, Zhujiang Hospital, Southern Medical University, No. 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China; Department of Pediatric Neurology, Zhujiang Hospital, Southern Medical University, 253 Gongye Avenue, Guangzhou, Guangdong 510282, PR China.
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6
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Yahya V, Di Fonzo A, Monfrini E. Genetic Evidence for Endolysosomal Dysfunction in Parkinson’s Disease: A Critical Overview. Int J Mol Sci 2023; 24:ijms24076338. [PMID: 37047309 PMCID: PMC10094484 DOI: 10.3390/ijms24076338] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/23/2023] [Accepted: 03/26/2023] [Indexed: 03/30/2023] Open
Abstract
Parkinson’s disease (PD) is the second most common neurodegenerative disorder in the aging population, and no disease-modifying therapy has been approved to date. The pathogenesis of PD has been related to many dysfunctional cellular mechanisms, however, most of its monogenic forms are caused by pathogenic variants in genes involved in endolysosomal function (LRRK2, VPS35, VPS13C, and ATP13A2) and synaptic vesicle trafficking (SNCA, RAB39B, SYNJ1, and DNAJC6). Moreover, an extensive search for PD risk variants revealed strong risk variants in several lysosomal genes (e.g., GBA1, SMPD1, TMEM175, and SCARB2) highlighting the key role of lysosomal dysfunction in PD pathogenesis. Furthermore, large genetic studies revealed that PD status is associated with the overall “lysosomal genetic burden”, namely the cumulative effect of strong and weak risk variants affecting lysosomal genes. In this context, understanding the complex mechanisms of impaired vesicular trafficking and dysfunctional endolysosomes in dopaminergic neurons of PD patients is a fundamental step to identifying precise therapeutic targets and developing effective drugs to modify the neurodegenerative process in PD.
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Affiliation(s)
- Vidal Yahya
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy;
- Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Neurology Unit, 20122 Milan, Italy;
| | - Alessio Di Fonzo
- Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Neurology Unit, 20122 Milan, Italy;
| | - Edoardo Monfrini
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy;
- Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Neurology Unit, 20122 Milan, Italy;
- Correspondence:
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Maj M, Taylor CL, Landau K, Toriello HV, Li D, Bhoj EJ, Hakonarson H, Nelson B, Gluschitz S, Walker RH, Sobering AK. A novel SYNJ1 homozygous variant causing developmental and epileptic encephalopathy in an Afro-Caribbean individual. Mol Genet Genomic Med 2022; 11:e2064. [PMID: 36148638 PMCID: PMC9834178 DOI: 10.1002/mgg3.2064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/08/2022] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND SYNJ1 encodes Synaptojanin-1, a dual-function poly-phosphoinositide phosphatase that is expressed in the brain to regulate neuronal synaptic vesicle dynamics. Biallelic SYNJ1 variants cause a spectrum of clinical manifestations, from early onset parkinsonism to developmental and epileptic encephalopathy. METHODS Proband-only exome sequencing was used to identify a homozygous SYNJ1 pathogenic variant in an individual with epileptic encephalopathy. Sanger sequencing was used to confirm the variant. RESULTS We present an Afro-Caribbean female who developed uncontrollable seizures shortly after birth, accompanied by developmental delay and severe generalized dystonia. She had homozygosity for a novel c.242-2A > G variant in SYNJ1 with both parents being heterozygous carriers. An older sister was reported to have had a similar presentation but was not examined. Both siblings died at an approximate age of 16 years. CONCLUSIONS We report a novel pathogenic variant in SYNJ1 present in homozygosity leading to developmental and epileptic encephalopathy. Currently, there are only 4 reports describing 10 individuals with SYNJ1-related developmental and epileptic encephalopathy. This case expands the clinical knowledge and the allelic heterogeneity associated with SYNJ1 variants.
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Affiliation(s)
- Mary Maj
- Department of BiochemistrySt. George's University School of MedicineSt. George'sGrenada
| | - Christie L. Taylor
- Augusta University/University of Georgia Medical Partnership Campus of the Medical College of GeorgiaAthensGeorgiaUSA
| | - Kevin Landau
- Department of BiochemistrySt. George's University School of MedicineSt. George'sGrenada
| | - Helga V. Toriello
- Department of Pediatrics and Human DevelopmentMichigan State UniversityEast LansingMichiganUSA
| | - Dong Li
- Center for Applied GenomicsThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA,Division of Human Genetics, Department of PediatricsThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA,Department of PediatricsUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvaniaUSA
| | - Elizabeth J. Bhoj
- Center for Applied GenomicsThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA,Division of Human Genetics, Department of PediatricsThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA,Department of PediatricsUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvaniaUSA
| | - Hakon Hakonarson
- Department of Pediatrics and Human DevelopmentMichigan State UniversityEast LansingMichiganUSA,Center for Applied GenomicsThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA,Department of PediatricsUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvaniaUSA
| | - Beverly Nelson
- Pediatrics WardGrenada General HospitalSt. George'sGrenada,Clinical Teaching UnitSt. George's University School of MedicineSt. George'sGrenada
| | - Sarah Gluschitz
- Department of Anatomical SciencesSt. George's University School of MedicineSt. George'sGrenada
| | - Ruth H. Walker
- Department of NeurologyJames J. Peters Veterans Affairs Medical CenterBronxNew YorkUSA,Department of NeurologyMount Sinai School of MedicineNew York CityNew YorkUSA
| | - Andrew K. Sobering
- Department of BiochemistrySt. George's University School of MedicineSt. George'sGrenada,Department of Basic Sciences, University of Georgia Health Sciences CampusAugusta University/University of Georgia Medical PartnershipAthensGeorgiaUSA,Windward Islands Research and Education FoundationSt. George'sGrenada
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8
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Schechter M, Sharon R. An Emerging Role for Phosphoinositides in the Pathophysiology of Parkinson’s Disease. JOURNAL OF PARKINSON'S DISEASE 2021; 11:1725-1750. [PMID: 34151859 PMCID: PMC8609718 DOI: 10.3233/jpd-212684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Recent data support an involvement of defects in homeostasis of phosphoinositides (PIPs) in the pathophysiology of Parkinson’s disease (PD). Genetic mutations have been identified in genes encoding for PIP-regulating and PIP-interacting proteins, that are associated with familial and sporadic PD. Many of these proteins are implicated in vesicular membrane trafficking, mechanisms that were recently highlighted for their close associations with PD. PIPs are phosphorylated forms of the membrane phospholipid, phosphatidylinositol. Their composition in the vesicle’s membrane of origin, as well as membrane of destination, controls vesicular membrane trafficking. We review the converging evidence that points to the involvement of PIPs in PD. The review describes PD- and PIP-associated proteins implicated in clathrin-mediated endocytosis and autophagy, and highlights the involvement of α-synuclein in these mechanisms.
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Affiliation(s)
- Meir Schechter
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, Israel
| | - Ronit Sharon
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem, Israel
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9
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Zhang D, Li B, Guo R, Wu J, Yang C, Jiang X, Zhang C, Yan H, Zhao Q, Wang Z, Wang Q, Huang R, Zhang Z, Hu X, Gao L. RAB5C, SYNJ1, and RNF19B promote male ankylosing spondylitis by regulating immune cell infiltration. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1011. [PMID: 34277811 PMCID: PMC8267299 DOI: 10.21037/atm-21-2721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/15/2021] [Indexed: 12/14/2022]
Abstract
Background This study aimed to identify the key genes related to male ankylosing spondylitis (AS) and to analyze the role of immune cell infiltration in the pathological process of this disease. Methods The AS dataset was downloaded from the Gene Expression Omnibus (GEO) public database, and the data of male healthy controls (M_HC) and male AS patients (M_AS) were extracted. R software was used to identify differentially expressed genes (DEGs). Functional and pathway enrichment analysis of the DEGs was performed. A protein-protein interaction (PPI) network was constructed, and the hub genes were screened out. All expression profile data were analyzed by weighted correlation network analysis (WGCNA) to screen out the hub genes, which were then intersected with the hub genes from the PPI network to obtain the key genes. Finally, the difference in immune cell infiltration in the two sets of samples was evaluated with CIBERSORT, and the correlation between the key genes and infiltrating immune cells was analyzed. Results A total of 689 DEGs were obtained, of which 395 genes were up-regulated and 294 genes were down-regulated. Functional and pathway enrichment analysis showed that DEGs were mainly enriched in pathways related to immune response. Based on the PPI analysis, five clusters with high scores were selected. Through WGCNA, 14 gene modules were obtained. The green module with the highest correlation was selected and intersected with the cluster previously obtained to obtain three key genes, RAB5C, SYNJ1, and RNF19B. Immune infiltration analysis found that monocytes and gamma delta T cells may be involved in the process of AS. Also, RAB5C, SYNJ1, and RNF19B are all related to increased levels of monocytes and macrophages. Conclusions RAB5C, SYNJ1, and RNF19B are key DEGs expressed in M_AS and may play a role in the disease’s occurrence and development through regulating immune cell functions.
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Affiliation(s)
- Di Zhang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China.,Department of Orthopedics, The Eighth Hospital of Sun Yat-sen University, Shenzhen, China
| | - Bo Li
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Rui Guo
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jionglin Wu
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Canchun Yang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xu Jiang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Chi Zhang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Haolin Yan
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Qiancheng Zhao
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Zheyu Wang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Qiwei Wang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Renyuan Huang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Zhilei Zhang
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xumin Hu
- Department of Spine Surgery, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Liangbin Gao
- Department of Orthopedics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
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10
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Ernest James Phillips T, Maguire E. Phosphoinositides: Roles in the Development of Microglial-Mediated Neuroinflammation and Neurodegeneration. Front Cell Neurosci 2021; 15:652593. [PMID: 33841102 PMCID: PMC8032904 DOI: 10.3389/fncel.2021.652593] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/08/2021] [Indexed: 12/11/2022] Open
Abstract
Microglia are increasingly recognized as vital players in the pathology of a variety of neurodegenerative conditions including Alzheimer’s (AD) and Parkinson’s (PD) disease. While microglia have a protective role in the brain, their dysfunction can lead to neuroinflammation and contributes to disease progression. Also, a growing body of literature highlights the seven phosphoinositides, or PIPs, as key players in the regulation of microglial-mediated neuroinflammation. These small signaling lipids are phosphorylated derivates of phosphatidylinositol, are enriched in the brain, and have well-established roles in both homeostasis and disease.Disrupted PIP levels and signaling has been detected in a variety of dementias. Moreover, many known AD disease modifiers identified via genetic studies are expressed in microglia and are involved in phospholipid metabolism. One of these, the enzyme PLCγ2 that hydrolyzes the PIP species PI(4,5)P2, displays altered expression in AD and PD and is currently being investigated as a potential therapeutic target.Perhaps unsurprisingly, neurodegenerative conditions exhibiting PIP dyshomeostasis also tend to show alterations in aspects of microglial function regulated by these lipids. In particular, phosphoinositides regulate the activities of proteins and enzymes required for endocytosis, toll-like receptor signaling, purinergic signaling, chemotaxis, and migration, all of which are affected in a variety of neurodegenerative conditions. These functions are crucial to allow microglia to adequately survey the brain and respond appropriately to invading pathogens and other abnormalities, including misfolded proteins. AD and PD therapies are being developed to target many of the above pathways, and although not yet investigated, simultaneous PIP manipulation might enhance the beneficial effects observed. Currently, only limited therapeutics are available for dementia, and although these show some benefits for symptom severity and progression, they are far from curative. Given the importance of microglia and PIPs in dementia development, this review summarizes current research and asks whether we can exploit this information to design more targeted, or perhaps combined, dementia therapeutics. More work is needed to fully characterize the pathways discussed in this review, but given the strength of the current literature, insights in this area could be invaluable for the future of neurodegenerative disease research.
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Affiliation(s)
| | - Emily Maguire
- UK Dementia Research Institute at Cardiff University, Cardiff, United Kingdom
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11
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Lesage S, Mangone G, Tesson C, Bertrand H, Benmahdjoub M, Kesraoui S, Arezki M, Singleton A, Corvol JC, Brice A. Clinical Variability of SYNJ1-Associated Early-Onset Parkinsonism. Front Neurol 2021; 12:648457. [PMID: 33841314 PMCID: PMC8027075 DOI: 10.3389/fneur.2021.648457] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 02/25/2021] [Indexed: 11/29/2022] Open
Abstract
Autosomal recessive early-onset parkinsonism is clinically and genetically heterogeneous. Mutations of three genes, PRKN, PINK1, and DJ-1 cause pure phenotypes usually characterized by levodopa-responsive Parkinson's disease. By contrast, mutations of other genes, including ATP13A2, PLA2G6, FBXO7, DNAJC6, SYNJ1, VPS13C, and PTRHD1, cause rarer, more severe diseases with a poor response to levodopa, generally with additional atypical features. We performed data mining on a gene panel or whole-exome sequencing in 460 index cases with early-onset (≤ 40 years) Parkinson's disease, including 57 with autosomal recessive disease and 403 isolated cases. We identified two isolated cases carrying biallelic mutations of SYNJ1 (double-heterozygous p.D791fs/p.Y232H and homozygous p. Y832C mutations) and two siblings with the recurrent homozygous p.R258Q mutation. All four variants were absent or rare in the Genome Aggregation Database, were predicted to be deleterious on in silico analysis and were found to be highly conserved between species. The patient with both the previously unknown p.D791fs and p.Y232H mutations presented with dystonia-parkinsonism accompanied by a frontal syndrome and oculomotor disturbances at the age of 39. In addition, two siblings from an Algerian consanguineous family carried the homozygous p.R258Q mutation and presented generalized tonic-clonic seizures during childhood, with severe intellectual disability, followed by progressive parkinsonism during their teens. By contrast, the isolated patient with the homozygous p. Y832C mutation, diagnosed at the age of 20, had typical parkinsonism, with no atypical symptoms and slow disease progression. Our findings expand the mutational spectrum and phenotypic profile of SYNJ1-related parkinsonism.
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Affiliation(s)
- Suzanne Lesage
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, CIC Neurosciences, Paris, France
| | - Graziella Mangone
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, CIC Neurosciences, Paris, France
| | - Christelle Tesson
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, CIC Neurosciences, Paris, France
| | - Hélène Bertrand
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, CIC Neurosciences, Paris, France
| | | | | | | | - Andrew Singleton
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
| | - Jean-Christophe Corvol
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, CIC Neurosciences, Paris, France
| | - Alexis Brice
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, CIC Neurosciences, Paris, France
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12
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Schechter M, Atias M, Abd Elhadi S, Davidi D, Gitler D, Sharon R. α-Synuclein facilitates endocytosis by elevating the steady-state levels of phosphatidylinositol 4,5-bisphosphate. J Biol Chem 2020; 295:18076-18090. [PMID: 33087443 PMCID: PMC7939461 DOI: 10.1074/jbc.ra120.015319] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/08/2020] [Indexed: 12/12/2022] Open
Abstract
α-Synuclein (α-Syn) is a protein implicated in the pathogenesis of Parkinson's disease (PD). It is an intrinsically disordered protein that binds acidic phospholipids. Growing evidence supports a role for α-Syn in membrane trafficking, including, mechanisms of endocytosis and exocytosis, although the exact role of α-Syn in these mechanisms is currently unclear. Here we investigate the associations of α-Syn with the acidic phosphoinositides (PIPs), phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2). Our results show that α-Syn colocalizes with PIP2 and the phosphorylated active form of the clathrin adaptor protein 2 (AP2) at clathrin-coated pits. Using endocytosis of transferrin as an indicator for clathrin-mediated endocytosis (CME), we find that α-Syn involvement in endocytosis is specifically mediated through PI(4,5)P2 levels on the plasma membrane. In accord with their effects on PI(4,5)P2 levels, the PD associated A30P, E46K, and A53T mutations in α-Syn further enhance CME in neuronal and nonneuronal cells. However, lysine to glutamic acid substitutions at the KTKEGV repeat domain of α-Syn, which interfere with phospholipid binding, are ineffective in enhancing CME. We further show that the rate of synaptic vesicle (SV) endocytosis is differentially affected by the α-Syn mutations and associates with their effects on PI(4,5)P2 levels, however, with the exception of the A30P mutation. This study provides evidence for a critical involvement of PIPs in α-Syn-mediated membrane trafficking.
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Affiliation(s)
- Meir Schechter
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Merav Atias
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Suaad Abd Elhadi
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Dana Davidi
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Daniel Gitler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ronit Sharon
- Department of Biochemistry and Molecular Biology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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13
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Paesmans J, Martin E, Deckers B, Berghmans M, Sethi R, Loeys Y, Pardon E, Steyaert J, Verstreken P, Galicia C, Versées W. A structure of substrate-bound Synaptojanin1 provides new insights in its mechanism and the effect of disease mutations. eLife 2020; 9:64922. [PMID: 33349335 PMCID: PMC7781601 DOI: 10.7554/elife.64922] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/16/2020] [Indexed: 12/13/2022] Open
Abstract
Synaptojanin1 (Synj1) is a phosphoinositide phosphatase, important in clathrin uncoating during endocytosis of presynaptic vesicles. It was identified as a potential drug target for Alzheimer's disease, Down syndrome, and TBC1D24-associated epilepsy, while also loss-of-function mutations in Synj1 are associated with epilepsy and Parkinson's disease. Despite its involvement in a range of disorders, structural, and detailed mechanistic information regarding the enzyme is lacking. Here, we report the crystal structure of the 5-phosphatase domain of Synj1. Moreover, we also present a structure of this domain bound to the substrate diC8-PI(3,4,5)P3, providing the first image of a 5-phosphatase with a trapped substrate in its active site. Together with an analysis of the contribution of the different inositide phosphate groups to catalysis, these structures provide new insights in the Synj1 mechanism. Finally, we analysed the effect of three clinical missense mutations (Y793C, R800C, Y849C) on catalysis, unveiling the molecular mechanisms underlying Synj1-associated disease.
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Affiliation(s)
- Jone Paesmans
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ella Martin
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Babette Deckers
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Marjolijn Berghmans
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ritika Sethi
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Yannick Loeys
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Els Pardon
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jan Steyaert
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium.,KU Leuven, Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
| | - Christian Galicia
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Wim Versées
- VIB-VUB Center for Structural Biology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
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14
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Meir S, Merav A, Suaad AE, Dana D, Daniel G, Ronit S. α-Synuclein facilitates endocytosis by elevating the steady-state levels of phosphatidylinositol 4,5-bisphosphate.. [DOI: 10.1101/2020.06.18.158709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Abstractα-Synuclein (α-Syn) is a protein implicated in the pathogenesis of Parkinson’s disease (PD). It is an intrinsically disordered protein that binds acidic phospholipids. Growing evidence supports a role for α-Syn in membrane trafficking, including, mechanisms of endocytosis and exocytosis, although the exact role of α-Syn in these mechanisms is currently unclear. Here we have investigated the role of α-Syn in membrane trafficking through its association with acidic phosphoinositides (PIPs), such as phosphatidylinositol 4,5-bisphosphate (PI4,5P2) and phosphatidylinositol 3,4-bisphosphate (PI3,4P2). Our results show that α-Syn colocalizes with PIP2 and the phosphorylated active form of the clathrin adaptor AP2 at clathrin-coated pits. Using endocytosis of transferrin, an indicator of clathrin mediated endocytosis (CME), we find that α-Syn involvement in endocytosis is specifically mediated through PI4,5P2 levels. We further show that the rate of synaptic vesicle (SV) endocytosis is differentially affected by α-Syn mutations. In accord with their effects on PI4,5P2 levels at the plasma membrane, the PD associated E46K and A53T mutations further enhance SV endocytosis. However, neither A30P mutation, nor Lysine to Glutamic acid substitutions at the KTKEGV repeat domain of α-Syn, that interfere with phospholipid binding, affect SV endocytosis. This study provides evidence for a critical involvement of PIPs in α-Syn-mediated membrane trafficking.Significance Statementα-Synuclein (α-Syn) protein is known for its causative role in Parkinson’s disease. α-Syn is normally involved in mechanisms of membrane trafficking, including endocytosis, exocytosis and synaptic vesicles cycling. However, a certain degree of controversy regarding the exact role of α-Syn in these mechanisms persists. Here we show that α-Syn acts to increase plasma membrane levels PI4,5P2 and PI3,4P2 to facilitate clathrin mediated and synaptic vesicles endocytosis. Based on the results, we suggest that α-Syn interactions with the acidic phosphoinositides facilitate a shift in their homeostasis to support endocytosis.
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