1
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Efthymiou S, Han W, Ilyas M, Li J, Yu Y, Scala M, Malintan NT, Ilyas M, Vavouraki N, Mankad K, Maroofian R, Rocca C, Salpietro V, Lakhani S, Mallack EJ, Palculict TB, Li H, Zhang G, Zafar F, Rana N, Takashima N, Matsunaga H, Manzoni C, Striano P, Lythgoe MF, Aruga J, Lu W, Houlden H. Human mutations in SLITRK3 implicated in GABAergic synapse development in mice. Front Mol Neurosci 2024; 17:1222935. [PMID: 38495551 PMCID: PMC10940442 DOI: 10.3389/fnmol.2024.1222935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 02/02/2024] [Indexed: 03/19/2024] Open
Abstract
This study reports on biallelic homozygous and monoallelic de novo variants in SLITRK3 in three unrelated families presenting with epileptic encephalopathy associated with a broad neurological involvement characterized by microcephaly, intellectual disability, seizures, and global developmental delay. SLITRK3 encodes for a transmembrane protein that is involved in controlling neurite outgrowth and inhibitory synapse development and that has an important role in brain function and neurological diseases. Using primary cultures of hippocampal neurons carrying patients' SLITRK3 variants and in combination with electrophysiology, we demonstrate that recessive variants are loss-of-function alleles. Immunostaining experiments in HEK-293 cells showed that human variants C566R and E606X change SLITRK3 protein expression patterns on the cell surface, resulting in highly accumulating defective proteins in the Golgi apparatus. By analyzing the development and phenotype of SLITRK3 KO (SLITRK3-/-) mice, the study shows evidence of enhanced susceptibility to pentylenetetrazole-induced seizure with the appearance of spontaneous epileptiform EEG as well as developmental deficits such as higher motor activities and reduced parvalbumin interneurons. Taken together, the results exhibit impaired development of the peripheral and central nervous system and support a conserved role of this transmembrane protein in neurological function. The study delineates an emerging spectrum of human core synaptopathies caused by variants in genes that encode SLITRK proteins and essential regulatory components of the synaptic machinery. The hallmark of these disorders is impaired postsynaptic neurotransmission at nerve terminals; an impaired neurotransmission resulting in a wide array of (often overlapping) clinical features, including neurodevelopmental impairment, weakness, seizures, and abnormal movements. The genetic synaptopathy caused by SLITRK3 mutations highlights the key roles of this gene in human brain development and function.
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Affiliation(s)
- Stephanie Efthymiou
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
- U.O.C. Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Giannina Gaslini, Genoa, Italy
| | - Wenyan Han
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Muhammad Ilyas
- Department of Biological Sciences, International Islamic University Islamabad, Islamabad, Pakistan
| | - Jun Li
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Yichao Yu
- Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, United Kingdom
| | - Marcello Scala
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy
- Pediatric Neurology and Muscular Diseases Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Giannina Gaslini, Genoa, Italy
| | - Nancy T. Malintan
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
| | - Muhammad Ilyas
- Centre for Omic Sciences, Islamia College Peshawar, Peshawar, Pakistan
| | - Nikoleta Vavouraki
- School of Pharmacy, University of Reading, Reading, United Kingdom
- Department of Mathematics and Statistics, University of Reading, Reading, United Kingdom
| | - Kshitij Mankad
- Department of Radiology, Great Ormond Street Hospital, London, United Kingdom
- Developmental Neurosciences Department, University College London (UCL) Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Reza Maroofian
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
| | - Clarissa Rocca
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
| | - Vincenzo Salpietro
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
| | - Shenela Lakhani
- Center for Neurogenetics, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, United States
| | - Eric J. Mallack
- Center for Neurogenetics, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, United States
| | | | - Hong Li
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
| | - Guojun Zhang
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
- Department of Pediatric Neurology, Children’s Healthcare of Atlanta, Atlanta, GA, United States
| | - Faisal Zafar
- Department of Pediatrics, Multan Hospital, Multan, Pakistan
| | - Nuzhat Rana
- Department of Pediatrics, Multan Hospital, Multan, Pakistan
| | - Noriko Takashima
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Saitama, Japan
| | - Hayato Matsunaga
- Department of Medical Pharmacology, Nagasaki University Institute of Biomedical Sciences, Nagasaki, Japan
| | - Claudia Manzoni
- School of Pharmacy, University College London, London, United Kingdom
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy
- Pediatric Neurology and Muscular Diseases Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Giannina Gaslini, Genoa, Italy
| | - Mark F. Lythgoe
- Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, United Kingdom
| | - Jun Aruga
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Saitama, Japan
- Department of Medical Pharmacology, Nagasaki University Institute of Biomedical Sciences, Nagasaki, Japan
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Henry Houlden
- Department of Neuromuscular Disorders, University College London (UCL) Queen Square Institute of Neurology, London, United Kingdom
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2
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Douthwaite JA, Brown CA, Ferdinand JR, Sharma R, Elliott J, Taylor MA, Malintan NT, Duvoisin H, Hill T, Delpuech O, Orton AL, Pitt H, Kuenzi F, Fish S, Nicholls DJ, Cuthbert A, Richards I, Ratcliffe G, Upadhyay A, Marklew A, Hewitt C, Ross-Thriepland D, Brankin C, Chodorge M, Browne G, Mander PK, DeWildt RM, Weaver S, Smee PA, van Kempen J, Bartlett JG, Allen PM, Koppe EL, Ashby CA, Phipps JD, Mehta N, Brierley DJ, Tew DG, Leveridge MV, Baddeley SM, Goodfellow IG, Green C, Abell C, Neely A, Waddell I, Rees S, Maxwell PH, Pangalos MN, Howes R, Clark R. Improving the efficiency and effectiveness of an industrial SARS-CoV-2 diagnostic facility. Sci Rep 2022; 12:3114. [PMID: 35210470 PMCID: PMC8873195 DOI: 10.1038/s41598-022-06873-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 02/07/2022] [Indexed: 11/24/2022] Open
Abstract
On 11th March 2020, the UK government announced plans for the scaling of COVID-19 testing, and on 27th March 2020 it was announced that a new alliance of private sector and academic collaborative laboratories were being created to generate the testing capacity required. The Cambridge COVID-19 Testing Centre (CCTC) was established during April 2020 through collaboration between AstraZeneca, GlaxoSmithKline, and the University of Cambridge, with Charles River Laboratories joining the collaboration at the end of July 2020. The CCTC lab operation focussed on the optimised use of automation, introduction of novel technologies and process modelling to enable a testing capacity of 22,000 tests per day. Here we describe the optimisation of the laboratory process through the continued exploitation of internal performance metrics, while introducing new technologies including the Heat Inactivation of clinical samples upon receipt into the laboratory and a Direct to PCR protocol that removed the requirement for the RNA extraction step. We anticipate that these methods will have value in driving continued efficiency and effectiveness within all large scale viral diagnostic testing laboratories.
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Affiliation(s)
| | | | - John R Ferdinand
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK.,Department of Medicine, University of Cambridge, Cambridge, UK
| | - Rahul Sharma
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK.,Department of Medicine, University of Cambridge, Cambridge, UK
| | - Jane Elliott
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | | | | | | | - Thomas Hill
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
| | | | | | - Haidee Pitt
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Fred Kuenzi
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
| | - Simon Fish
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK.,GSK R&D Tech, Stevenage, UK
| | | | | | - Ian Richards
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
| | - Giles Ratcliffe
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
| | | | - Abigail Marklew
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
| | - Craig Hewitt
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Ian G Goodfellow
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK
| | - Clive Green
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Chris Abell
- Vice Chancellor's Office, University of Cambridge, Cambridge, UK
| | - Andy Neely
- Vice Chancellor's Office, University of Cambridge, Cambridge, UK
| | - Ian Waddell
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
| | - Steve Rees
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | | | | | - Rob Howes
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Roger Clark
- Charles River Laboratories, Chesterford Research Park, Saffron Walden, UK
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3
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Chelban V, Alsagob M, Kloth K, Chirita-Emandi A, Vandrovcova J, Maroofian R, Davagnanam I, Bakhtiari S, AlSayed MD, Rahbeeni Z, AlZaidan H, Malintan NT, Johannsen J, Efthymiou S, Ghayoor Karimiani E, Mankad K, Al-Shahrani SA, Beiraghi Toosi M, AlShammari M, Groppa S, Haridy NA, AlQuait L, Qari A, Huma R, Salih MA, Almass R, Almutairi FB, Hamad MH, Alorainy IA, Ramzan K, Imtiaz F, Puiu M, Kruer MC, Bierhals T, Wood NW, Colak D, Houlden H, Kaya N. Genetic and phenotypic characterization of NKX6-2-related spastic ataxia and hypomyelination. Eur J Neurol 2019; 27:334-342. [PMID: 31509304 PMCID: PMC6946857 DOI: 10.1111/ene.14082] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/21/2019] [Indexed: 12/22/2022]
Abstract
Background and purpose Hypomyelinating leukodystrophies are a heterogeneous group of genetic disorders with a wide spectrum of phenotypes and a high rate of genetically unsolved cases. Bi‐allelic mutations in NKX6‐2 were recently linked to spastic ataxia 8 with hypomyelinating leukodystrophy. Methods Using a combination of homozygosity mapping, exome sequencing, and detailed clinical and neuroimaging assessment a series of new NKX6‐2 mutations in a multicentre setting is described. Then, all reported NKX6‐2 mutations and those identified in this study were combined and an in‐depth analysis of NKX6‐2‐related disease spectrum was provided. Results Eleven new cases from eight families of different ethnic backgrounds carrying compound heterozygous and homozygous pathogenic variants in NKX6‐2 were identified, evidencing a high NKX6‐2 mutation burden in the hypomyelinating leukodystrophy disease spectrum. Our data reveal a phenotype spectrum with neonatal onset, global psychomotor delay and worse prognosis at the severe end and a childhood onset with mainly motor phenotype at the milder end. The phenotypic and neuroimaging expression in NKX6‐2 is described and it is shown that phenotypes with epilepsy in the absence of overt hypomyelination and diffuse hypomyelination without seizures can occur. Conclusions NKX6‐2 mutations should be considered in patients with autosomal recessive, very early onset of nystagmus, cerebellar ataxia with hypotonia that rapidly progresses to spasticity, particularly when associated with neuroimaging signs of hypomyelination. Therefore, it is recommended that NXK6‐2 should be included in hypomyelinating leukodystrophy and spastic ataxia diagnostic panels.
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Affiliation(s)
- V Chelban
- Department of Neuromuscular Diseases, University College London Institute of Neurology, London, UK.,Department of Neurology and Neurosurgery, Institute of Emergency Medicine, Chisinau, Moldova
| | - M Alsagob
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - K Kloth
- Institute of Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - A Chirita-Emandi
- Genetics Department, University 'Victor Babes', Timisoara, Romania
| | - J Vandrovcova
- Department of Neuromuscular Diseases, University College London Institute of Neurology, London, UK
| | - R Maroofian
- Genetics Research Centre, Molecular and Clinical Sciences Institute, St George's University of London, London, UK
| | - I Davagnanam
- Brain Repair and Rehabilitation, University College London Institute of Neurology, London, UK
| | - S Bakhtiari
- Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA.,Department of Child Health, Cellular and Molecular Medicine, Department of Neurology, University of Arizona College of Medicine Phoenix, Phoenix, AZ, USA
| | - M D AlSayed
- Medical Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - Z Rahbeeni
- Medical Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - H AlZaidan
- Medical Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - N T Malintan
- Clinical and Experimental Epilepsy, University College London Institute of Neurology, London, UK
| | - J Johannsen
- Department of Paediatrics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - S Efthymiou
- Department of Neuromuscular Diseases, University College London Institute of Neurology, London, UK
| | - E Ghayoor Karimiani
- Genetics Research Centre, Molecular and Clinical Sciences Institute, St George's University of London, London, UK
| | - K Mankad
- Great Ormond Street Hospitals, London, UK
| | | | - M Beiraghi Toosi
- Department of Paediatric Diseases, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - M AlShammari
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - S Groppa
- Department of Neurology and Neurosurgery, Institute of Emergency Medicine, Chisinau, Moldova
| | - N A Haridy
- Department of Neuromuscular Diseases, University College London Institute of Neurology, London, UK.,Department of Neurology and Psychiatry, Assiut University Hospital, Assiut, Egypt
| | - L AlQuait
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - A Qari
- Medical Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - R Huma
- Medical Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - M A Salih
- Neurology Division, Department of Pediatrics, College of Medicine, King Saud University KFSHRC, Riyadh, Saudi Arabia
| | - R Almass
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - F B Almutairi
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - M H Hamad
- Neurology Division, Department of Pediatrics, College of Medicine, King Saud University KFSHRC, Riyadh, Saudi Arabia
| | - I A Alorainy
- Department of Radiology & Medical Imaging, College of Medicine, King Saud University KFSHRC, Riyadh, Saudi Arabia
| | - K Ramzan
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - F Imtiaz
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
| | - M Puiu
- Genetics Department, University 'Victor Babes', Timisoara, Romania
| | - M C Kruer
- Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ, USA.,Department of Child Health, Cellular and Molecular Medicine, Department of Neurology, University of Arizona College of Medicine Phoenix, Phoenix, AZ, USA
| | - T Bierhals
- Institute of Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - N W Wood
- Department of Neuromuscular Diseases, University College London Institute of Neurology, London, UK
| | - D Colak
- Department of Biostatistics, Epidemiology and Scientific Computing, KFSHRC, Riyadh, Saudi Arabia
| | - H Houlden
- Department of Neuromuscular Diseases, University College London Institute of Neurology, London, UK
| | - N Kaya
- Department of Genetics, KFSHRC, Riyadh, Saudi Arabia
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4
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Praschberger R, Lowe SA, Malintan NT, Giachello CNG, Patel N, Houlden H, Kullmann DM, Baines RA, Usowicz MM, Krishnakumar SS, Hodge JJL, Rothman JE, Jepson JEC. Mutations in Membrin/GOSR2 Reveal Stringent Secretory Pathway Demands of Dendritic Growth and Synaptic Integrity. Cell Rep 2017; 21:97-109. [PMID: 28978487 PMCID: PMC5640804 DOI: 10.1016/j.celrep.2017.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/17/2017] [Accepted: 09/01/2017] [Indexed: 11/16/2022] Open
Abstract
Mutations in the Golgi SNARE (SNAP [soluble NSF attachment protein] receptor) protein Membrin (encoded by the GOSR2 gene) cause progressive myoclonus epilepsy (PME). Membrin is a ubiquitous and essential protein mediating ER-to-Golgi membrane fusion. Thus, it is unclear how mutations in Membrin result in a disorder restricted to the nervous system. Here, we use a multi-layered strategy to elucidate the consequences of Membrin mutations from protein to neuron. We show that the pathogenic mutations cause partial reductions in SNARE-mediated membrane fusion. Importantly, these alterations were sufficient to profoundly impair dendritic growth in Drosophila models of GOSR2-PME. Furthermore, we show that Membrin mutations cause fragmentation of the presynaptic cytoskeleton coupled with transsynaptic instability and hyperactive neurotransmission. Our study highlights how dendritic growth is vulnerable even to subtle secretory pathway deficits, uncovers a role for Membrin in synaptic function, and provides a comprehensive explanatory basis for genotype-phenotype relationships in GOSR2-PME.
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Affiliation(s)
- Roman Praschberger
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Simon A Lowe
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK
| | - Nancy T Malintan
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Carlo N G Giachello
- Faculty of Biology, Medicine, and Health, Division of Neuroscience & Experimental Psychology, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Nian Patel
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Henry Houlden
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Dimitri M Kullmann
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Richard A Baines
- Faculty of Biology, Medicine, and Health, Division of Neuroscience & Experimental Psychology, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Maria M Usowicz
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK
| | - Shyam S Krishnakumar
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK; Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - James J L Hodge
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, UK
| | - James E Rothman
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK; Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - James E C Jepson
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.
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5
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Martin S, Papadopulos A, Tomatis VM, Sierecki E, Malintan NT, Gormal RS, Giles N, Johnston WA, Alexandrov K, Gambin Y, Collins BM, Meunier FA. Increased polyubiquitination and proteasomal degradation of a Munc18-1 disease-linked mutant causes temperature-sensitive defect in exocytosis. Cell Rep 2014; 9:206-218. [PMID: 25284778 DOI: 10.1016/j.celrep.2014.08.059] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 07/31/2014] [Accepted: 08/23/2014] [Indexed: 12/23/2022] Open
Abstract
Munc18-1 is a critical component of the core machinery controlling neuroexocytosis. Recently, mutations in Munc18-1 leading to the development of early infantile epileptic encephalopathy have been discovered. However, which degradative pathway controls Munc18-1 levels and how it impacts on neuroexocytosis in this pathology is unknown. Using neurosecretory cells deficient in Munc18, we show that a disease-linked mutation, C180Y, renders the protein unstable at 37°C. Although the mutated protein retains its function as t-SNARE chaperone, neuroexocytosis is impaired, a defect that can be rescued at a lower permissive temperature. We reveal that Munc18-1 undergoes K48-linked polyubiquitination, which is highly increased by the mutation, leading to proteasomal, but not lysosomal, degradation. Our data demonstrate that functional Munc18-1 levels are controlled through polyubiquitination and proteasomal degradation. The C180Y disease-causing mutation greatly potentiates this degradative pathway, rendering Munc18-1 unable to facilitate neuroexocytosis, a phenotype that is reversed at a permissive temperature.
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Affiliation(s)
- Sally Martin
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Andreas Papadopulos
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Vanesa M Tomatis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Emma Sierecki
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nancy T Malintan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nichole Giles
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Wayne A Johnston
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kirill Alexandrov
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yann Gambin
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Frederic A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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6
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Martin S, Tomatis VM, Papadopulos A, Christie MP, Malintan NT, Gormal RS, Sugita S, Martin JL, Collins BM, Meunier FA. The Munc18-1 domain 3a loop is essential for neuroexocytosis but not for syntaxin-1A transport to the plasma membrane. J Cell Sci 2013; 126:2353-60. [PMID: 23761923 DOI: 10.1242/jcs.126813] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Munc18-1 plays a dual role in transporting syntaxin-1A (Sx1a) to the plasma membrane and regulating SNARE-mediated membrane fusion. As impairment of either function leads to a common exocytic defect, assigning specific roles for various Munc18-1 domains has proved difficult. Structural analyses predict that a loop region in Munc18-1 domain 3a could catalyse the conversion of Sx1a from a 'closed', fusion-incompetent to an 'open', fusion-competent conformation. As this conversion occurs at the plasma membrane, mutations in this loop could potentially separate the chaperone and exocytic functions of Munc18-1. Expression of a Munc18-1 deletion mutant lacking 17 residues of the domain 3a loop (Munc18-1(Δ317-333)) in PC12 cells deficient in endogenous Munc18 (DKD-PC12 cells) fully rescued transport of Sx1a to the plasma membrane, but not exocytic secretory granule fusion. In vitro binding of Munc18-1(Δ317-333) to Sx1a was indistinguishable from that of full-length Munc18-1, consistent with the critical role of the closed conformation in Sx1a transport. However, in DKD-PC12 cells, Munc18-1(Δ317-333) binding to Sx1a was greatly reduced compared to that of full-length Munc18-1, suggesting that closed conformation binding contributes little to the overall interaction at the cell surface. Furthermore, we found that Munc18-1(Δ317-333) could bind SNARE complexes in vitro, suggesting that additional regulatory factors underpin the exocytic function of Munc18-1 in vivo. Together, these results point to a defined role for Munc18-1 in facilitating exocytosis linked to the loop region of domain 3a that is clearly distinct from its function in Sx1a transport.
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Affiliation(s)
- Sally Martin
- Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia
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7
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Tomatis VM, Papadopulos A, Malintan NT, Martin S, Wallis T, Gormal RS, Kendrick-Jones J, Buss F, Meunier FA. Myosin VI small insert isoform maintains exocytosis by tethering secretory granules to the cortical actin. ACTA ACUST UNITED AC 2013; 200:301-20. [PMID: 23382463 PMCID: PMC3563687 DOI: 10.1083/jcb.201204092] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Before undergoing neuroexocytosis, secretory granules (SGs) are mobilized and tethered to the cortical actin network by an unknown mechanism. Using an SG pull-down assay and mass spectrometry, we found that myosin VI was recruited to SGs in a Ca(2+)-dependent manner. Interfering with myosin VI function in PC12 cells reduced the density of SGs near the plasma membrane without affecting their biogenesis. Myosin VI knockdown selectively impaired a late phase of exocytosis, consistent with a replenishment defect. This exocytic defect was selectively rescued by expression of the myosin VI small insert (SI) isoform, which efficiently tethered SGs to the cortical actin network. These myosin VI SI-specific effects were prevented by deletion of a c-Src kinase phosphorylation DYD motif, identified in silico. Myosin VI SI thus recruits SGs to the cortical actin network, potentially via c-Src phosphorylation, thereby maintaining an active pool of SGs near the plasma membrane.
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Affiliation(s)
- Vanesa M Tomatis
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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Tomatis VM, Papadopulos A, Malintan NT, Martin S, Wallis T, Gormal RS, Kendrick-Jones J, Buss F, Meunier FA. Myosin VI small insert isoform maintains exocytosis by tethering secretory granules to the cortical actin. J Gen Physiol 2013. [DOI: 10.1085/jgp1413oia5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Han GA, Malintan NT, Saw NMN, Li L, Han L, Meunier FA, Collins BM, Sugita S. Munc18-1 domain-1 controls vesicle docking and secretion by interacting with syntaxin-1 and chaperoning it to the plasma membrane. Mol Biol Cell 2011; 22:4134-49. [PMID: 21900502 PMCID: PMC3204074 DOI: 10.1091/mbc.e11-02-0135] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Munc18-1 plays pleiotropic roles in neurosecretion by acting as 1) a molecular chaperone of syntaxin-1, 2) a mediator of dense-core vesicle docking, and 3) a priming factor for soluble N-ethylmaleimide-sensitive factor attachment protein receptor-mediated membrane fusion. However, how these functions are executed and whether they are correlated remains unclear. Here we analyzed the role of the domain-1 cleft of Munc18-1 by measuring the abilities of various mutants (D34N, D34N/M38V, K46E, E59K, K46E/E59K, K63E, and E66A) to bind and chaperone syntaxin-1 and to restore the docking and secretion of dense-core vesicles in Munc18-1/-2 double-knockdown cells. We identified striking correlations between the abilities of these mutants to bind and chaperone syntaxin-1 with their ability to restore vesicle docking and secretion. These results suggest that the domain-1 cleft of Munc18-1 is essential for binding to syntaxin-1 and thereby critical for its chaperoning, docking, and secretory functions. Our results demonstrate that the effect of the alleged priming mutants (E59K, D34N/M38V) on exocytosis can largely be explained by their reduced syntaxin-1-chaperoning functions. Finally, our data suggest that the intracellular expression and distribution of syntaxin-1 determines the level of dense-core vesicle docking.
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Affiliation(s)
- Gayoung A Han
- Division of Fundamental Neurobiology, University Health Network, Toronto ON M5T 2S8, Canada
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Abstract
Munc18-1 plays essential roles in neurosecretion by interacting with syntaxin-1 and controlling the formation of the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) complex. At least three important functions of Munc18-1 have been proposed: (i) molecular chaperone of syntaxin-1 for appropriate localization and expression of syntaxin-1, (ii) priming/stimulation of the SNARE-mediated membrane fusion, and (iii) docking of large dense-core vesicles to the plasma membrane. Similarly, at least two different binding modes have been proposed for the interaction between Munc18-1 and syntaxin-1: (i) binary binding to a 'closed' conformation of syntaxin-1, and (ii) binding to the N-terminal peptide of syntaxin-1, which is thought to enable an interaction with the quaternary SNARE complex and/or further stabilize the binary interaction between Munc18-1 and closed syntaxin-1. Recent structural analyses have identified critical Munc18-1 residues implicated in these different modes of binding. These have recently been tested functionally in rescue experiments using Munc18-1 null neurons, chromaffin cells and Munc18-1/-2 knockdown PC12 cells, allowing remarkable progress to be made in the structural/functional understanding of Munc18-1. In this review, we summarize these recent advances and attempt to propose an updated model of the pleiotropic functions of Munc18-1 in neuroexocytosis.
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Affiliation(s)
- Gayoung A Han
- Division of Fundamental Neurobiology, University Health Network, Toronto, Ontario, Canada
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11
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Han L, Jiang T, Han GA, Malintan NT, Xie L, Wang L, Tse FW, Gaisano HY, Collins BM, Meunier FA, Sugita S. Rescue of Munc18-1 and -2 double knockdown reveals the essential functions of interaction between Munc18 and closed syntaxin in PC12 cells. Mol Biol Cell 2009; 20:4962-75. [PMID: 19812250 DOI: 10.1091/mbc.e09-08-0712] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Munc18-1 binds to syntaxin-1A via two distinct sites referred to as the "closed" conformation and N terminus binding. The latter has been shown to stimulate soluble N-ethylmaleimide-sensitive factor attachment protein receptor-mediated exocytosis, whereas the former is believed to be inhibitory or dispensable. To precisely define the contributions of each binding mode, we have engineered Munc18-1/-2 double knockdown neurosecretory cells and show that not only syntaxin-1A and -1B but also syntaxin-2 and -3 are significantly reduced as a result of Munc18-1 and -2 knockdown. Syntaxin-1 was mislocalized and the regulated secretion was abolished. We next examined the abilities of Munc18-1 mutants to rescue the defective phenotypes. Mutation (K46E/E59K) of Munc18-1 that selectively prevents binding to closed syntaxin-1 was unable to restore syntaxin-1 expression, localization, or secretion. In contrast, mutations (F115E/E132A) of Munc18-1 that selectively impair binding to the syntaxin-1 N terminus could still rescue the defective phenotypes. Our results indicate that Munc18-1 and -2 act in concert to support the expression of a broad range of syntaxins and to deliver syntaxin-1 to the plasma membrane. Our studies also indicate that the binding to the closed conformation of syntaxin is essential for Munc18-1 stimulatory action, whereas the binding to syntaxin N terminus plays a more limited role in neurosecretory cells.
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Affiliation(s)
- Liping Han
- Division of Fundamental Neurobiology, University Health Network, Toronto, Ontario, M5T 2S8, Canada
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Malintan NT, Nguyen TH, Han L, Latham CF, Osborne SL, Wen PJ, Lim SJT, Sugita S, Collins BM, Meunier FA. Abrogating Munc18-1-SNARE complex interaction has limited impact on exocytosis in PC12 cells. J Biol Chem 2009; 284:21637-46. [PMID: 19483085 DOI: 10.1074/jbc.m109.013508] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal communication relies on the fusion of neurotransmitter-containing vesicles with the plasma membrane. The soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) proteins initiate membrane fusion through the formation of the SNARE complex, a process tightly regulated by Sec1/Munc18-1 (SM) proteins. The emerging trend is that SM proteins promote SNARE-mediated membrane fusion by binding to a Syntaxin N-terminal motif. Here we report that mutations in the hydrophobic pocket of Munc18-1 (F115E and E132A), predicted to disrupt the N-terminal Sx1a interaction have a modest effect on binding to Sx1a in its free state, but abolish binding to the SNARE complex. Overexpression of the Munc18-1 mutant in PC12 cells lacking Munc18-1 rescues both neuroexocytosis and the plasma membrane localization of Syntaxin. However, total internal reflection fluorescence microscopy analysis reveals that expression of a Munc18-1 double mutant reduces the rate of vesicle fusion, an effect only detectable at the onset of stimulation. The Munc18-1 hydrophobic pocket is therefore critical for SNARE complex binding. However, mutations abrogating this interaction have a limited impact on Ca(2+)-dependent exocytosis in PC12 cells.
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Affiliation(s)
- Nancy T Malintan
- Queensland Brain Institute and School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
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Mustafa AM, Malintan NT, Seelan S, Zhan Z, Mohamed Z, Hassan J, Pendek R, Hussain R, Ito N. Phytoestrogens levels determination in the cord blood from Malaysia rural and urban populations. Toxicol Appl Pharmacol 2007; 222:25-32. [PMID: 17490695 DOI: 10.1016/j.taap.2007.03.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 02/22/2007] [Accepted: 03/06/2007] [Indexed: 11/21/2022]
Abstract
This study is a result of an analysis of free and conjugated phytoestrogens daidzein, genistein, daidzin, genistin and coumesterol in human cord blood plasma using LCMS. Cord blood was collected from urban and rural populations of Malaysia (n=300) to establish a simple preliminary database on the levels of the analyzed compounds in the collected samples. The study also aimed to look at the levels of phytoestrogens in babies during birth as this may have a profound effect on the developmental process. The sample clean up was carried out by solid-phase extraction using C18 column and passed through DEAE sephadex gel before analysis by LCMS. The mean concentrations of total phytoestrogens were daidzein (1.4+/-2.9 ng/ml), genistein (3.7+/-2.8 ng/ml), daidzin (3.5+/-3.1 ng/ml), genistin (19.5+/-4.2 ng/ml) and coumesterol (3.3+/-3.3 ng/ml). Distribution of phytoestrogen was found to be higher in samples collected from rural areas compared to that of urban areas.
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Affiliation(s)
- A M Mustafa
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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Malintan NT, Mohd MA. Determination of sulfonamides in selected Malaysian swine wastewater by high-performance liquid chromatography. J Chromatogr A 2006; 1127:154-60. [PMID: 16806241 DOI: 10.1016/j.chroma.2006.06.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/22/2006] [Accepted: 06/01/2006] [Indexed: 11/26/2022]
Abstract
An analytical HPLC method for the simultaneous determination of eight sulfonamides in swine wastewater was developed. The samples were collected from three states in Malaysia. Sample clean up was carried out by employing solid-phase extraction using a 60 mg Oasis HLB (Waters) cartridge with 3 ml reservoir. The HPLC column used was Supelcosil C18 (250 mm x 4.6mm I.D.) and elution was carried out using gradient mode. The mobile phases used were acetonitrile and 0.5% acetic acid in purified water. Antibiotics were detected using UV absorbance at 272 nm. Recoveries obtained for sulphanilamide ranged from 31.9+/-5.1% to 36.2+/-1.0%, while recoveries for other sulfa drugs studied were from 91.9+/-5.0% to 106.0+/-1.1%. The limit of quantitation (LOQ) for sulfamerazine, sulfamethazine and sulfamethoxypyridazine was 7.5 ng/L, while the LOQ for the other studied antibiotics was 5.0 ng/L. The method was used to analyse sulfonamides in wastewater collected from selected Malaysian swine facilities.
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Affiliation(s)
- Nancy T Malintan
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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