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Freibauer A, Wohlleben M, Boelman C. STXBP1-Related Disorders: Clinical Presentation, Molecular Function, Treatment, and Future Directions. Genes (Basel) 2023; 14:2179. [PMID: 38137001 PMCID: PMC10742812 DOI: 10.3390/genes14122179] [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: 11/10/2023] [Revised: 11/27/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
In recent years, the affordability and availability of genetic testing have led to its increased use in clinical care. The increased frequency of testing has led to STXBP1 variants being identified as one of the more common variants associated with neurological disorders. In this review, we aim to summarize the common clinical phenotypes associated with STXBP1 pathogenic variants, provide an overview of their known natural history, and discuss current research into the genotype to phenotype correlation. We will also provide an overview of the suspected normal function of the STXBP1-encoded Munc18-1 protein, animal models, and experimental techniques that have been developed to study its function and use this information to try to explain the diverse phenotypes associated with STXBP1-related disorders. Finally, we will explore current therapies for STXBP1 disorders, including an overview of treatment goals for STXBP1-related disorders, a discussion of the current evidence for therapies, and future directions of personalized medications for STXBP1-related disorders.
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Affiliation(s)
- Alexander Freibauer
- Division of Neurology, BC Children’s Hospital, Vancouver, BC V6H 3N1, Canada;
- Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Mikayla Wohlleben
- Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Cyrus Boelman
- Division of Neurology, BC Children’s Hospital, Vancouver, BC V6H 3N1, Canada;
- Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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2
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Tang F, Xiao D, Chen L, Gao H, Li X. Role of Munc18-1 in the biological functions and pathogenesis of neurological disorders (Review). Mol Med Rep 2021; 23:198. [PMID: 33495808 PMCID: PMC7821349 DOI: 10.3892/mmr.2021.11837] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 12/30/2020] [Indexed: 11/06/2022] Open
Abstract
The release of neurotransmitters following the fusion of synaptic vesicles and the presynaptic membrane is an important process in the transmission of neuronal information. Syntaxin-binding protein 1 (Munc18-1) is a synaptic fusion protein binding protein, which mainly regulates synaptic vesicle fusion and neurotransmitter release by interacting with soluble N-ethylmaleimide sensitive factor attachment protein receptor. In addition to affecting neurotransmitter transmission, Munc18-1 is also involved in regulating neurosynaptic plasticity, neurodevelopment and neuroendocrine cell release functions (including thyroxine and insulin release). A number of previous studies have demonstrated that Munc18-1 has diverse and vital biological functions, and that its abnormal expression serves an important role in the pathogenesis of a variety of neurological diseases, including epileptic encephalopathy, schizophrenia, autism, Parkinsons disease, Alzheimers disease, multiple sclerosis, Duchennes muscular dystrophy and neuronal ceroid lipofuscinosis. The present review summarizes the function of Munc18-1 and its possible relationship to the pathogenesis of various neurological diseases.
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Affiliation(s)
- Fajuan Tang
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Dongqiong Xiao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Lin Chen
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Hu Gao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Xihong Li
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
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3
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van Berkel AA, Santos TC, Shaweis H, van Weering JRT, Toonen RF, Verhage M. Loss of MUNC18-1 leads to retrograde transport defects in neurons. J Neurochem 2020; 157:450-466. [PMID: 33259669 PMCID: PMC8247427 DOI: 10.1111/jnc.15256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/24/2020] [Accepted: 11/26/2020] [Indexed: 12/11/2022]
Abstract
Loss of the exocytic Sec1/MUNC18 protein MUNC18-1 or its target-SNARE partners SNAP25 and syntaxin-1 results in rapid, cell-autonomous and unexplained neurodegeneration, which is independent of their known role in synaptic vesicle exocytosis. cis-Golgi abnormalities are the earliest cellular phenotypes before degeneration occurs. Here, we investigated whether loss of MUNC18-1 causes defects in intracellular membrane transport pathways in primary murine neurons that may explain neurodegeneration. Electron, confocal and super resolution microscopy confirmed that loss of MUNC18-1 expression results in a smaller cis-Golgi. In addition, we now show that medial-Golgi and the trans-Golgi Network are also affected. However, stacking and cisternae ultrastructure of the Golgi were normal. Overall, ultrastructure of null mutant neurons was remarkably normal just hours before cell death occurred. By synchronizing protein trafficking by conditional cargo retention in the endoplasmic reticulum using selective hooks (RUSH) and immunocytochemistry, we show that anterograde Endoplasmic Reticulum-to-Golgi and Golgi exit of endogenous and exogenous proteins were normal. In contrast, loss of MUNC18-1 caused reduced retrograde Cholera Toxin B-subunit transport from the plasma membrane to the Golgi. In addition, MUNC18-1-deficiency resulted in abnormalities in retrograde TrkB trafficking in an antibody uptake assay. We conclude that MUNC18-1 deficient neurons have normal anterograde but reduced retrograde transport to the Golgi. The impairments in retrograde pathways suggest a role of MUNC18-1 in endosomal SNARE-dependent fusion and provide a plausible explanation for the observed Golgi abnormalities and cell death in MUNC18-1 deficient neurons.
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Affiliation(s)
- Annemiek A van Berkel
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), University Medical Center Amsterdam, Amsterdam, The Netherlands.,Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, Amsterdam, The Netherlands
| | - Tatiana C Santos
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, Amsterdam, The Netherlands
| | - Hesho Shaweis
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, Amsterdam, The Netherlands
| | - Jan R T van Weering
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, Amsterdam, The Netherlands
| | - Matthijs Verhage
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), University Medical Center Amsterdam, Amsterdam, The Netherlands.,Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, Amsterdam, The Netherlands
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4
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Gowrisankaran S, Houy S, Del Castillo JGP, Steubler V, Gelker M, Kroll J, Pinheiro PS, Schwitters D, Halbsgut N, Pechstein A, van Weering JRT, Maritzen T, Haucke V, Raimundo N, Sørensen JB, Milosevic I. Endophilin-A coordinates priming and fusion of neurosecretory vesicles via intersectin. Nat Commun 2020; 11:1266. [PMID: 32152276 PMCID: PMC7062783 DOI: 10.1038/s41467-020-14993-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 02/12/2020] [Indexed: 12/17/2022] Open
Abstract
Endophilins-A are conserved endocytic adaptors with membrane curvature-sensing and -inducing properties. We show here that, independently of their role in endocytosis, endophilin-A1 and endophilin-A2 regulate exocytosis of neurosecretory vesicles. The number and distribution of neurosecretory vesicles were not changed in chromaffin cells lacking endophilin-A, yet fast capacitance and amperometry measurements revealed reduced exocytosis, smaller vesicle pools and altered fusion kinetics. The levels and distributions of the main exocytic and endocytic factors were unchanged, and slow compensatory endocytosis was not robustly affected. Endophilin-A’s role in exocytosis is mediated through its SH3-domain, specifically via a direct interaction with intersectin-1, a coordinator of exocytic and endocytic traffic. Endophilin-A not able to bind intersectin-1, and intersectin-1 not able to bind endophilin-A, resulted in similar exocytic defects in chromaffin cells. Altogether, we report that two endocytic proteins, endophilin-A and intersectin-1, are enriched on neurosecretory vesicles and regulate exocytosis by coordinating neurosecretory vesicle priming and fusion. Endophilins-A are conserved membrane-associated proteins required for endocytosis. Here, the authors report that endophilins-A also promote exocytosis of neurosecretory vesicles by coordinating priming and fusion through intersectin-1, independently of their roles in different types of endocytosis.
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Affiliation(s)
- Sindhuja Gowrisankaran
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Sébastien Houy
- University of Copenhagen, Department for Neuroscience, Faculty of Health and Medical Sciences, Copenhagen, Denmark
| | - Johanna G Peña Del Castillo
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Vicky Steubler
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Monika Gelker
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Jana Kroll
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Paulo S Pinheiro
- University of Copenhagen, Department for Neuroscience, Faculty of Health and Medical Sciences, Copenhagen, Denmark.,Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Dirk Schwitters
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Nils Halbsgut
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany
| | - Arndt Pechstein
- Leibniz Research Institute for Molecular Pharmacology, Molecular Physiology and Cell Biology Section, Berlin, Germany
| | - Jan R T van Weering
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam UMC, Amsterdam, The Netherlands
| | - Tanja Maritzen
- Leibniz Research Institute for Molecular Pharmacology, Molecular Physiology and Cell Biology Section, Berlin, Germany
| | - Volker Haucke
- Leibniz Research Institute for Molecular Pharmacology, Molecular Physiology and Cell Biology Section, Berlin, Germany
| | - Nuno Raimundo
- Institute for Cellular Biochemistry, University Medical Center Göttingen (UMG), Göttingen, Germany
| | - Jakob B Sørensen
- University of Copenhagen, Department for Neuroscience, Faculty of Health and Medical Sciences, Copenhagen, Denmark.
| | - Ira Milosevic
- European Neuroscience Institute-A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society Göttingen, Göttingen, Germany.
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First person – Maria Pons-Vizcarra. J Cell Sci 2019. [DOI: 10.1242/jcs.241885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Maria Pons-Vizcarra is first author on ‘MUNC18-1 regulates the submembrane F-actin network, independently of syntaxin1 targeting, via hydrophobicity in β-sheet 10’, published in JCS. Maria is a PhD student in the lab of Matthijs Verhage at Vrije Universiteit Amsterdam, where she investigates the mechanisms of dense core vesicle release.
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