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Kim J, Teng LY, Shaker B, Na D, Koh HY, Kwon SS, Lee JS, Kim HD, Kang HC, Kim SH. Genotypes and phenotypes of DNM1 encephalopathy. J Med Genet 2023; 60:1076-1083. [PMID: 37248033 DOI: 10.1136/jmg-2023-109233] [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: 02/23/2023] [Accepted: 04/30/2023] [Indexed: 05/31/2023]
Abstract
BACKGROUND Variants in the dynamin-1 (DNM1) gene typically cause synaptopathy, leading to developmental and epileptic encephalopathy (DEE). We aimed to determine the genotypic and phenotypic spectrum of DNM1 encephalopathy beyond DEE. METHODS Electroclinical phenotyping and genotyping of patients with a DNM1 variant were conducted for patients undergoing next-generation sequencing at our centre, followed by a systematic review. RESULTS Six patients with heterozygous DNM1 variants were identified in our cohort. Three had a typical DEE phenotype characterised by epileptic spasms, tonic seizures and severe-to-profound intellectual disability with pathogenic variants located in the GTPase or middle domain. The other three patients had atypical phenotypes of milder cognitive impairment and focal epilepsy. Genotypically, two patients with atypical phenotypes had variants located in the GTPase domain, while the third patient had a novel variant (p.M648R) in the linker region between pleckstrin homology and GTPase effector domains. The third patient with an atypical phenotype showed normal development until he developed febrile status epilepticus. Our systematic review on 55 reported cases revealed that those with GTPase or middle domain variants had more severe intellectual disability (p<0.001) and lower functional levels of ambulation (p=0.001) or speech and language (p<0.001) than the rest. CONCLUSION DNM1-related phenotypes encompass a wide spectrum of epilepsy and neurodevelopmental disorders, with specific variants underlying different phenotypes.
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Affiliation(s)
- Jeehyun Kim
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
| | - Lip-Yuen Teng
- Paediatric Neurology, Hospital Tunku Azizah, Kuala Lumpur, Malaysia
| | - Bilal Shaker
- Department of Biomedical Engineering, Chung-Ang University, Seoul, Korea
| | - Dokyun Na
- Department of Biomedical Engineering, Chung-Ang University, Seoul, Korea
| | - Hyun Yong Koh
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Soon Sung Kwon
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seodaemun-gu, Korea
| | - Joon Soo Lee
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Seoul, Korea
- Epilepsy Research Institute, Yonsei University College of Medicine, Epilepsy Research Institute, Seoul, Korea
| | - Heung Dong Kim
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Seoul, Korea
- Epilepsy Research Institute, Yonsei University College of Medicine, Epilepsy Research Institute, Seoul, Korea
| | - Hoon-Chul Kang
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Seoul, Korea
- Epilepsy Research Institute, Yonsei University College of Medicine, Epilepsy Research Institute, Seoul, Korea
| | - Se Hee Kim
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Seoul, Korea
- Epilepsy Research Institute, Yonsei University College of Medicine, Epilepsy Research Institute, Seoul, Korea
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2
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Villavicencio Gonzalez E, Dhindsa RS. Studying ultra-rare variants in STX1A uncovers a novel neurodevelopmental disorder. Eur J Hum Genet 2023; 31:973-974. [PMID: 37029317 PMCID: PMC10474260 DOI: 10.1038/s41431-023-01348-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 04/09/2023] Open
Affiliation(s)
- Esmeralda Villavicencio Gonzalez
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
- Jan and Dan Duncan Neurologic Research Institute at Texas Children's Hospital, Houston, TX, USA.
| | - Ryan S Dhindsa
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
- Jan and Dan Duncan Neurologic Research Institute at Texas Children's Hospital, Houston, TX, USA.
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3
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Bonnycastle K, Dobson KL, Blumrich EM, Gajbhiye A, Davenport EC, Pronot M, Steinruecke M, Trost M, Gonzalez-Sulser A, Cousin MA. Reversal of cell, circuit and seizure phenotypes in a mouse model of DNM1 epileptic encephalopathy. Nat Commun 2023; 14:5285. [PMID: 37648685 PMCID: PMC10468497 DOI: 10.1038/s41467-023-41035-w] [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: 02/20/2023] [Accepted: 08/17/2023] [Indexed: 09/01/2023] Open
Abstract
Dynamin-1 is a large GTPase with an obligatory role in synaptic vesicle endocytosis at mammalian nerve terminals. Heterozygous missense mutations in the dynamin-1 gene (DNM1) cause a novel form of epileptic encephalopathy, with pathogenic mutations clustering within regions required for its essential GTPase activity. We reveal the most prevalent pathogenic DNM1 mutation, R237W, disrupts dynamin-1 enzyme activity and endocytosis when overexpressed in central neurons. To determine how this mutation impacted cell, circuit and behavioural function, we generated a mouse carrying the R237W mutation. Neurons from heterozygous mice display dysfunctional endocytosis, in addition to altered excitatory neurotransmission and seizure-like phenotypes. Importantly, these phenotypes are corrected at the cell, circuit and in vivo level by the drug, BMS-204352, which accelerates endocytosis. Here, we demonstrate a credible link between dysfunctional endocytosis and epileptic encephalopathy, and importantly reveal that synaptic vesicle recycling may be a viable therapeutic target for monogenic intractable epilepsies.
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Affiliation(s)
- Katherine Bonnycastle
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK.
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK.
- Service de Génétique Médicale, Centre Hospitalier Universitaire (CHU) Sainte-Justine, Université de Montréal, Montreal, QC, Canada.
| | - Katharine L Dobson
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
| | - Eva-Maria Blumrich
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
| | - Akshada Gajbhiye
- Newcastle University Biosciences Institute, Faculty of Medical Sciences, NE2 4HH, Newcastle upon Tyne, UK
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
| | - Marie Pronot
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
| | - Moritz Steinruecke
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
| | - Matthias Trost
- Newcastle University Biosciences Institute, Faculty of Medical Sciences, NE2 4HH, Newcastle upon Tyne, UK
| | - Alfredo Gonzalez-Sulser
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK.
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, EH8 9XD, Edinburgh, Scotland, UK.
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4
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Harms FL, Weiss D, Lisfeld J, Alawi M, Kutsche K. A deep intronic variant in DNM1 in a patient with developmental and epileptic encephalopathy creates a splice acceptor site and affects only transcript variants including exon 10a. Neurogenetics 2023; 24:171-180. [PMID: 37039969 DOI: 10.1007/s10048-023-00716-w] [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: 01/30/2023] [Accepted: 03/28/2023] [Indexed: 04/12/2023]
Abstract
DNM1 developmental and epileptic encephalopathy (DEE) is characterized by severe to profound intellectual disability, hypotonia, movement disorder, and refractory epilepsy, typically presenting with infantile spasms. Most of the affected individuals had de novo missense variants in DNM1. DNM1 undergoes alternative splicing that results in expression of six different transcript variants. One alternatively spliced region affects the tandemly arranged exons 10a and 10b, producing isoforms DNM1A and DNM1B, respectively. Pathogenic variants in the DNM1 coding region affect all transcript variants. Recently, a de novo DNM1 NM_001288739.1:c.1197-8G > A variant located in intron 9 has been reported in several unrelated individuals with DEE that causes in-frame insertion of two amino acids and leads to disease through a dominant-negative mechanism. We report on a patient with DEE and a de novo DNM1 variant NM_001288739.2:c.1197-46C > G in intron 9, upstream of exon 10a. By RT-PCR and Sanger sequencing using fibroblast-derived cDNA of the patient, we identified aberrantly spliced DNM1 mRNAs with exon 9 spliced to the last 45 nucleotides of intron 9 followed by exon 10a (NM_001288739.2:r.1196_1197ins[1197-1_1197-45]). The encoded DNM1A mutant is predicted to contain 15 novel amino acids between Ile398 and Arg399 [NP_001275668.1:p.(Ile398_Arg399ins15)] and likely functions in a dominant-negative manner, similar to other DNM1 mutants. Our data confirm the importance of the DNM1 isoform A for normal human brain function that is underscored by previously reported predominant expression of DMN1A transcripts in pediatric brain, functional differences of the mouse Dnm1a and Dnm1b isoforms, and the Dnm1 fitful mouse, an epilepsy mouse model.
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Affiliation(s)
- Frederike L Harms
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - Deike Weiss
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jasmin Lisfeld
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - Malik Alawi
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
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5
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Laiman J, Lin SS, Liu YW. Dynamins in human diseases: differential requirement of dynamin activity in distinct tissues. Curr Opin Cell Biol 2023; 81:102174. [PMID: 37230036 DOI: 10.1016/j.ceb.2023.102174] [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: 02/16/2023] [Revised: 04/12/2023] [Accepted: 04/24/2023] [Indexed: 05/27/2023]
Abstract
Dynamin, a 100-kDa GTPase, is one of the most-characterized membrane fission machineries catalyzing vesicle release from plasma membrane during endocytosis. The human genome encodes three dynamins: DNM1, DNM2 and DNM3, with high amino acid similarity but distinct expression patterns. Ever since the discoveries of dynamin mutations associated with human diseases in 2005, dynamin has become a paradigm for studying pathogenic mechanisms of mutant proteins from the aspects of structural biology, cell biology, model organisms as well as therapeutic strategy development. Here, we review the diseases and pathogenic mechanisms caused by mutations of DNM1 and DNM2, focusing on the activity requirement and regulation of dynamins in different tissues.
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Affiliation(s)
- Jessica Laiman
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shan-Shan Lin
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ya-Wen Liu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan; Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
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6
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Kontaxi C, Ivanova D, Davenport EC, Kind PC, Cousin MA. Epilepsy-Related CDKL5 Deficiency Slows Synaptic Vesicle Endocytosis in Central Nerve Terminals. J Neurosci 2023; 43:2002-2020. [PMID: 36759195 PMCID: PMC10027047 DOI: 10.1523/jneurosci.1537-22.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 12/20/2022] [Accepted: 01/09/2023] [Indexed: 02/11/2023] Open
Abstract
Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a severe early-onset epileptic encephalopathy resulting mainly from de novo mutations in the X-linked CDKL5 gene. To determine whether loss of presynaptic CDKL5 function contributes to CDD, we examined synaptic vesicle (SV) recycling in primary hippocampal neurons generated from Cdkl5 knockout rat males. Using a genetically encoded reporter, we revealed that CDKL5 is selectively required for efficient SV endocytosis. We showed that CDKL5 kinase activity is both necessary and sufficient for optimal SV endocytosis, since kinase-inactive mutations failed to correct endocytosis in Cdkl5 knockout neurons, whereas the isolated CDKL5 kinase domain fully restored SV endocytosis kinetics. Finally, we demonstrated that CDKL5-mediated phosphorylation of amphiphysin 1, a putative presynaptic target, is not required for CDKL5-dependent control of SV endocytosis. Overall, our findings reveal a key presynaptic role for CDKL5 kinase activity and enhance our insight into how its dysfunction may culminate in CDD.SIGNIFICANCE STATEMENT Loss of cyclin-dependent kinase like 5 (CDKL5) function is a leading cause of monogenic childhood epileptic encephalopathy. However, information regarding its biological role is scarce. In this study, we reveal a selective presynaptic role for CDKL5 in synaptic vesicle endocytosis and that its protein kinase activity is both necessary and sufficient for this role. The isolated protein kinase domain is sufficient to correct this loss of function, which may facilitate future gene therapy strategies if presynaptic dysfunction is proven to be central to the disorder. It also reveals that a CDKL5-specific substrate is located at the presynapse, the phosphorylation of which is required for optimal SV endocytosis.
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Affiliation(s)
- Christiana Kontaxi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Daniela Ivanova
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Peter C Kind
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, EH8 9XD, United Kingdom
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7
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Parthasarathy S, Ruggiero SM, Gelot A, Soardi FC, Ribeiro BFR, Pires DEV, Ascher DB, Schmitt A, Rambaud C, Represa A, Xie HM, Lusk L, Wilmarth O, McDonnell PP, Juarez OA, Grace AN, Buratti J, Mignot C, Gras D, Nava C, Pierce SR, Keren B, Kennedy BC, Pena SDJ, Helbig I, Cuddapah VA. A recurrent de novo splice site variant involving DNM1 exon 10a causes developmental and epileptic encephalopathy through a dominant-negative mechanism. Am J Hum Genet 2022; 109:2253-2269. [PMID: 36413998 PMCID: PMC9748255 DOI: 10.1016/j.ajhg.2022.11.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 11/01/2022] [Indexed: 11/23/2022] Open
Abstract
Heterozygous pathogenic variants in DNM1 cause developmental and epileptic encephalopathy (DEE) as a result of a dominant-negative mechanism impeding vesicular fission. Thus far, pathogenic variants in DNM1 have been studied with a canonical transcript that includes the alternatively spliced exon 10b. However, after performing RNA sequencing in 39 pediatric brain samples, we find the primary transcript expressed in the brain includes the downstream exon 10a instead. Using this information, we evaluated genotype-phenotype correlations of variants affecting exon 10a and identified a cohort of eleven previously unreported individuals. Eight individuals harbor a recurrent de novo splice site variant, c.1197-8G>A (GenBank: NM_001288739.1), which affects exon 10a and leads to DEE consistent with the classical DNM1 phenotype. We find this splice site variant leads to disease through an unexpected dominant-negative mechanism. Functional testing reveals an in-frame upstream splice acceptor causing insertion of two amino acids predicted to impair oligomerization-dependent activity. This is supported by neuropathological samples showing accumulation of enlarged synaptic vesicles adherent to the plasma membrane consistent with impaired vesicular fission. Two additional individuals with missense variants affecting exon 10a, p.Arg399Trp and p.Gly401Asp, had a similar DEE phenotype. In contrast, one individual with a missense variant affecting exon 10b, p.Pro405Leu, which is less expressed in the brain, had a correspondingly less severe presentation. Thus, we implicate variants affecting exon 10a as causing the severe DEE typically associated with DNM1-related disorders. We highlight the importance of considering relevant isoforms for disease-causing variants as well as the possibility of splice site variants acting through a dominant-negative mechanism.
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Affiliation(s)
- Shridhar Parthasarathy
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, PA 19146, USA
| | - Sarah McKeown Ruggiero
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, PA 19146, USA
| | - Antoinette Gelot
- AP-HP, Hôpital Armand-Trousseau, Service d'Anatomie Pathologique, 75012 Paris, France; INMED INSERM U 901 Parc Scientifique de Luminy, 13273 Marseille, France; Centre de Recherche Clinique ConCer-LD, Paris, France
| | - Fernanda C Soardi
- GENE - Núcleo de Genética Médica, Belo Horizonte, MG, Brazil; Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Laboratório de Genômica Clínica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Douglas E V Pires
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia; Systems and Computational Biology, Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3052, Australia; School of Computing and Information Systems, University of Melbourne, Melbourne, VIC 3053, Australia
| | - David B Ascher
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia; Systems and Computational Biology, Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3052, Australia; School of Chemistry and Molecular Biology, University of Queensland, St Lucia, QLD 4072, Australia
| | - Alain Schmitt
- INSERM U 1016, Institut Cochin, Paris, France; CNRS UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Caroline Rambaud
- AP-HP, Hôpital Raymond-Poincaré, Laboratoire Anatomie Pathologique, Garches, France
| | - Alfonso Represa
- INMED, INSERM, Aix-Marseille Université, Campus de Luminy, 13009 Marseille, France
| | - Hongbo M Xie
- Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, PA 19146, USA
| | - Laina Lusk
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, PA 19146, USA
| | - Olivia Wilmarth
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Pamela Pojomovsky McDonnell
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Olivia A Juarez
- Baylor College of Medicine Genetics Clinic, Children's Hospital of San Antonio, San Antonio, TX, USA
| | - Alexandra N Grace
- Baylor College of Medicine Genetics Clinic, Children's Hospital of San Antonio, San Antonio, TX, USA
| | - Julien Buratti
- AP-HP, Hôpital de la Pitié Salpêtrière, Département de Génétique, 75013 Paris, France
| | - Cyril Mignot
- AP-HP, Hôpital de la Pitié Salpêtrière, Département de Génétique, 75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, INSERM U 1127, CNRS UMR 7225, ICM, 75013 Paris, France; AP-HP, Hôpital Robert Debré, Service de Neurologie Pediatrique et de Maladies Métaboliques, 75019 Paris, France
| | - Domitille Gras
- AP-HP, Hôpital Robert Debré, Service de Neurologie Pediatrique et de Maladies Métaboliques, 75019 Paris, France
| | - Caroline Nava
- AP-HP, Hôpital de la Pitié Salpêtrière, Département de Génétique, 75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, INSERM U 1127, CNRS UMR 7225, ICM, 75013 Paris, France; AP-HP, Hôpital Robert Debré, Service de Neurologie Pediatrique et de Maladies Métaboliques, 75019 Paris, France
| | - Samuel R Pierce
- The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Physical Therapy, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Boris Keren
- AP-HP, Hôpital de la Pitié Salpêtrière, Département de Génétique, 75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, INSERM U 1127, CNRS UMR 7225, ICM, 75013 Paris, France; AP-HP, Hôpital Robert Debré, Service de Neurologie Pediatrique et de Maladies Métaboliques, 75019 Paris, France
| | - Benjamin C Kennedy
- Division of Neurosurgery, Children's Hospital of Philadelphia, Philadelphia, PA 19146, USA; Department of Neurosurgery, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sergio D J Pena
- GENE - Núcleo de Genética Médica, Belo Horizonte, MG, Brazil; Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Laboratório de Genômica Clínica, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ingo Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Biomedical and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, PA 19146, USA; Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Vishnu Anand Cuddapah
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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8
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AlTassan R, AlQudairy H, Alromayan R, Alfalah A, AlHarbi OA, González-Álvarez AC, Arold ST, Kaya N. Clinical, Radiological, and Genetic Characterization of a Patient with a Novel Homoallelic Loss-of-Function Variant in DNM1. Genes (Basel) 2022; 13:genes13122252. [PMID: 36553519 PMCID: PMC9777962 DOI: 10.3390/genes13122252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/02/2022] Open
Abstract
Heterozygous pathogenic variants in DNM1 are linked to an autosomal dominant form of epileptic encephalopathy. Recently, homozygous loss-of-function variants in DNM1 were reported to cause an autosomal recessive form of developmental and epileptic encephalopathy in unrelated patients. Here, we investigated a singleton from a first-degree cousin marriage who presented with facial dysmorphism, global developmental delay, seizure disorder, and nystagmus. To identify the involvement of any likely genetic cause, diagnostic clinical exome sequencing was performed. Comprehensive filtering revealed a single plausible candidate variant in DNM1. Sanger sequencing of the trio, the patient, and her parents, confirmed the full segregation of the variant. The variant is a deletion leading to a premature stop codon and is predicted to cause a protein truncation. Structural modeling implicated a complete loss of function of the Dynamin 1 (DNM1). Such mutation is predicted to impair the nucleotide binding, dimer formation, and GTPase activity of DNM1. Our study expands the phenotypic spectrum of pathogenic homozygous loss-of-function variants in DNM1.
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Affiliation(s)
- Ruqaiah AlTassan
- Department of Medical Genomics, Centre for Genomic Medicine, MBC: 75, P.O. Box 3354, King Faisal Specialist Hospital, and Research Centre, Riyadh 11211, Saudi Arabia
- College of Medicine, P.O. Box 50927, AlFaisal University, Riyadh 11533, Saudi Arabia
| | - Hanan AlQudairy
- Translational Genomic Department, Centre for Genomic Medicine, MBC: 03, P.O. Box 3354, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Rakan Alromayan
- Translational Genomic Department, Centre for Genomic Medicine, MBC: 03, P.O. Box 3354, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
- College of Medicine, King Saud University, Riyadh 11451, Saudi Arabia
| | - Abdullah Alfalah
- Department of Medical Genomics, Centre for Genomic Medicine, MBC: 75, P.O. Box 3354, King Faisal Specialist Hospital, and Research Centre, Riyadh 11211, Saudi Arabia
| | - Omar A. AlHarbi
- Department of Radiology, MBC: 28, P.O. Box 3354, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
| | - Ana C. González-Álvarez
- Bioengineering Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Stefan T. Arold
- Bioengineering Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- Computational Biology Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Centre de Biologie Structurale (CBS), INSERM, CNRS, Université de Montpellier, F-34090 Montpellier, France
| | - Namik Kaya
- Translational Genomic Department, Centre for Genomic Medicine, MBC: 03, P.O. Box 3354, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia
- Correspondence: ; Tel.: +966-112162919 (ext. 39612)
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9
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Anderson RH, Sochacki KA, Vuppula H, Scott BL, Bailey EM, Schultz MM, Kerkvliet JG, Taraska JW, Hoppe AD, Francis KR. Sterols lower energetic barriers of membrane bending and fission necessary for efficient clathrin-mediated endocytosis. Cell Rep 2021; 37:110008. [PMID: 34788623 PMCID: PMC8620193 DOI: 10.1016/j.celrep.2021.110008] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 08/03/2021] [Accepted: 10/26/2021] [Indexed: 01/16/2023] Open
Abstract
Clathrin-mediated endocytosis (CME) is critical for cellular signal transduction, receptor recycling, and membrane homeostasis in mammalian cells. Acute depletion of cholesterol disrupts CME, motivating analysis of CME dynamics in the context of human disorders of cholesterol metabolism. We report that inhibition of post-squalene cholesterol biosynthesis impairs CME. Imaging of membrane bending dynamics and the CME pit ultrastructure reveals prolonged clathrin pit lifetimes and shallow clathrin-coated structures, suggesting progressive impairment of curvature generation correlates with diminishing sterol abundance. Sterol structural requirements for efficient CME include 3′ polar head group and B-ring conformation, resembling the sterol structural prerequisites for tight lipid packing and polarity. Furthermore, Smith-Lemli-Opitz fibroblasts with low cholesterol abundance exhibit deficits in CME-mediated transferrin internalization. We conclude that sterols lower the energetic costs of membrane bending during pit formation and vesicular scission during CME and suggest that reduced CME activity may contribute to cellular phenotypes observed within disorders of cholesterol metabolism. Anderson et al. demonstrate that sterol abundance and identity play a dominant role in facilitating clathrin-mediated endocytosis. Detailed analyses of clathrin-coated pits under sterol depletion support a requirement for sterol-mediated membrane bending during multiple stages of endocytosis, implicating endocytic dysfunction within the pathogenesis of disorders of cholesterol metabolism.
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Affiliation(s)
- Ruthellen H Anderson
- Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57105, USA; Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD 57104, USA
| | - Kem A Sochacki
- Laboratory of Molecular Biophysics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Harika Vuppula
- Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA; BioSystems Networks and Translational Research Center, Brookings, SD 57007, USA
| | - Brandon L Scott
- Nanoscience and Nanoengineering, South Dakota School of Mines & Technology, Rapid City, SD 57701, USA
| | - Elizabeth M Bailey
- Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA; BioSystems Networks and Translational Research Center, Brookings, SD 57007, USA
| | - Maycie M Schultz
- Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD 57104, USA
| | - Jason G Kerkvliet
- Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA; BioSystems Networks and Translational Research Center, Brookings, SD 57007, USA
| | - Justin W Taraska
- Laboratory of Molecular Biophysics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Adam D Hoppe
- Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA; BioSystems Networks and Translational Research Center, Brookings, SD 57007, USA.
| | - Kevin R Francis
- Cellular Therapies and Stem Cell Biology Group, Sanford Research, Sioux Falls, SD 57104, USA; Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57105, USA.
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10
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Proteins related to ictogenesis and seizure clustering in chronic epilepsy. Sci Rep 2021; 11:21508. [PMID: 34728717 PMCID: PMC8563854 DOI: 10.1038/s41598-021-00956-6] [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: 08/25/2021] [Accepted: 10/14/2021] [Indexed: 12/01/2022] Open
Abstract
Seizure clustering is a common phenomenon in epilepsy. Protein expression profiles during a seizure cluster might reflect the pathomechanism underlying ictogenesis. We performed proteomic analyses to identify proteins with a specific temporal expression pattern in cluster phases and to demonstrate their potential pathomechanistic role. Pilocarpine epilepsy model mice with confirmed cluster pattern of spontaneous recurrent seizures by long-term video-electroencpehalography were sacrificed at the onset, peak, or end of a seizure cluster or in the seizure-free period. Proteomic analysis was performed in the hippocampus and the cortex. Differentially expressed proteins (DEPs) were identified and classified according to their temporal expression pattern. Among the five hippocampal (HC)-DEP classes, HC-class 1 (66 DEPs) represented disrupted cell homeostasis due to clustered seizures, HC-class 2 (63 DEPs) cluster-onset downregulated processes, HC-class 3 (42 DEPs) cluster-onset upregulated processes, and HC-class 4 (103 DEPs) consequences of clustered seizures. Especially, DEPs in HC-class 3 were hippocampus-specific and involved in axonogenesis, synaptic vesicle assembly, and neuronal projection, indicating their pathomechanistic roles in ictogenesis. Key proteins in HC-class 3 were highly interconnected and abundantly involved in those biological processes. This study described the seizure cluster-associated spatiotemporal regulation of protein expression. HC-class 3 provides insights regarding ictogenesis-related processes.
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11
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Yigit G, Sheffer R, Daana M, Li Y, Kaygusuz E, Mor-Shakad H, Altmüller J, Nürnberg P, Douiev L, Kaulfuss S, Burfeind P, Wollnik B, Brockmann K. Loss-of-function variants in DNM1 cause a specific form of developmental and epileptic encephalopathy only in biallelic state. J Med Genet 2021; 59:549-553. [PMID: 34172529 PMCID: PMC9132866 DOI: 10.1136/jmedgenet-2021-107769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/08/2021] [Indexed: 11/23/2022]
Abstract
Background Developmental and epileptic encephalopathies (DEEs) represent a group of severe neurological disorders characterised by an onset of refractory seizures during infancy or early childhood accompanied by psychomotor developmental delay or regression. DEEs are genetically heterogeneous with, to date, more than 80 different genetic subtypes including DEE31 caused by heterozygous missense variants in DNM1. Methods We performed a detailed clinical characterisation of two unrelated patients with DEE and used whole-exome sequencing to identify causative variants in these individuals. The identified variants were tested for cosegregation in the respective families. Results We excluded pathogenic variants in known, DEE-associated genes. We identified homozygous nonsense variants, c.97C>T; p.(Gln33*) in family 1 and c.850C>T; p.(Gln284*) in family 2, in the DNM1 gene, indicating that biallelic, loss-of-function pathogenic variants in DNM1 cause DEE. Conclusion Our finding that homozygous, loss-of-function variants in DNM1 cause DEE expands the spectrum of pathogenic variants in DNM1. All parents who were heterozygous carriers of the identified loss-of-function variants were healthy and did not show any clinical symptoms, indicating that the type of mutation in DNM1 determines the pattern of inheritance.
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Affiliation(s)
- Gökhan Yigit
- Institute of Human Genetics, University Medical Center Göttingen, Gottingen, Germany
| | - Ruth Sheffer
- Department of Human Genetics, Hadassah University Hospital, Jerusalem, Israel
| | - Muhannad Daana
- Child Development Institute, Clalit Health Services, Tel Aviv, Israel
| | - Yun Li
- Institute of Human Genetics, University Medical Center Göttingen, Gottingen, Germany
| | - Emrah Kaygusuz
- Institute of Human Genetics, University Medical Center Göttingen, Gottingen, Germany.,Molecular Biology and Genetics, Bilecik Şeyh Edebali University, Bilecik, Turkey
| | - Hagar Mor-Shakad
- Department of Human Genetics, Hadassah University Hospital, Jerusalem, Israel
| | - Janine Altmüller
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Liza Douiev
- Department of Human Genetics, Hadassah University Hospital, Jerusalem, Israel
| | - Silke Kaulfuss
- Institute of Human Genetics, University Medical Center Göttingen, Gottingen, Germany
| | - Peter Burfeind
- Institute of Human Genetics, University Medical Center Göttingen, Gottingen, Germany
| | - Bernd Wollnik
- Institute of Human Genetics, University Medical Center Göttingen, Gottingen, Germany .,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Gottingen, Gottingen, Germany
| | - Knut Brockmann
- Interdisciplinary Pediatric Center for Children with Developmental Disabilities and Severe Chronic Disorders, University Medical Center Göttingen, Gottingen, Germany
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12
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Motta M, Consentino MC, Fontana A, Sciuto L, Falsaperla R, Praticò ER, Salafia S, Zanghì A, Praticò AD. DNM1 Gene and Its Related Epileptic Phenotypes. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1727258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractThe phenotypic variety associated to mutations in dynamin 1 (DNM1), codifying the presynaptic protein DNM1 has been increasingly reported, mainly related to encephalopathy with intractable epilepsy; currently, it is known the phenotype related to DNM1 gene mutations is relatively homogeneous with developmental delay, hypotonia, and epilepsy characterized by infantile spasms and possible progression to Lennox-Gastaut syndrome. By examining all the papers published until 2020 (18 articles), we compared data from 30 patients (extrapolated from 5 papers) with DNM1 mutations, identifying 26 patients with de novo mutations in DNM1. Nine patients (33.3%) reported the recurrent mutation p.Arg237Trp. A usual phenotype observed comprises severe to deep developmental delay and muscular hypotonia in all patients with epilepsy beginning with infantile spasms, which often evolved into Lennox-Gastaut syndrome. Data about GTPase or central domains mutations, and existing structural modeling and functional suggest a dominant negative effect on DMN1 function. Generally genetic epilepsies consist of a wide spectrum of clinical features, unlike that, DNM1-related CNS impairment phenotype is quite uniform. In up to one third of patients it has been found variant p.Arg237Trp, which is one of the most frequent variant detected in epileptic encephalopathies. The understanding of DNM1 function opens up the chance that this gene would become a new therapeutic target for epilepsies.
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Affiliation(s)
- Milena Motta
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Maria Chiara Consentino
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Alessandra Fontana
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Laura Sciuto
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
| | | | | | - Antonio Zanghì
- Department of Medical and Surgical Sciences and Advanced Technology “G.F. Ingrassia,” University of Catania, Catania, Italy
| | - Andrea D. Praticò
- Department of Clinical and Experimental Medicine, Unit of Rare Diseases of the Nervous System in Childhood, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy
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13
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Altered Fast Synaptic Transmission in a Mouse Model of DNM1-Associated Developmental Epileptic Encephalopathy. eNeuro 2021; 8:ENEURO.0269-20.2020. [PMID: 33372033 PMCID: PMC7986544 DOI: 10.1523/eneuro.0269-20.2020] [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: 06/12/2020] [Revised: 12/01/2020] [Accepted: 12/07/2020] [Indexed: 12/05/2022] Open
Abstract
Developmental epileptic encephalopathies (DEEs) are severe seizure disorders that occur in infants and young children, characterized by developmental delay, cognitive decline, and early mortality. Recent efforts have identified a wide variety of genetic variants that cause DEEs. Among these, variants in the DNM1 gene have emerged as definitive causes of DEEs, including infantile spasms and Lennox–Gastaut syndrome. A mouse model of Dnm1-associated DEE, known as “Fitful” (Dnm1Ftfl), recapitulates key features of the disease, including spontaneous seizures, early lethality, and neuronal degeneration. Previous work showed that DNM1 is a key regulator of synaptic vesicle (SV) endocytosis and synaptic transmission and suggested that inhibitory neurotransmission may be more reliant on DNM1 function than excitatory transmission. The Dnm1Ftfl variant is thought to encode a dominant negative DNM1 protein; however, the effects of the Dnm1Ftfl variant on synaptic transmission are largely unknown. To understand these synaptic effects, we recorded from pairs of cultured mouse cortical neurons and characterized all four major connection types [excitation of excitation (E-E), inhibition of inhibition (I-I), E-I, I-E]. Miniature and spontaneous EPSCs and IPSCs were larger, but less frequent, at all Dnm1Ftfl synaptic types, and Dnm1Ftfl neurons had reduced expression of excitatory and inhibitory SV markers. Baseline evoked transmission, however, was reduced only at inhibitory synapses onto excitatory neurons, because of a smaller pool of releasable SVs. In addition to these synaptic alterations, Dnm1Ftfl neurons degenerated later in development, although their activity levels were reduced, suggesting that Dnm1Ftfl may impair synaptic transmission and neuronal health through distinct mechanisms.
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14
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Marshall GF, Gonzalez-Sulser A, Abbott CM. Modelling epilepsy in the mouse: challenges and solutions. Dis Model Mech 2021; 14:dmm.047449. [PMID: 33619078 PMCID: PMC7938804 DOI: 10.1242/dmm.047449] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In most mouse models of disease, the outward manifestation of a disorder can be measured easily, can be assessed with a trivial test such as hind limb clasping, or can even be observed simply by comparing the gross morphological characteristics of mutant and wild-type littermates. But what if we are trying to model a disorder with a phenotype that appears only sporadically and briefly, like epileptic seizures? The purpose of this Review is to highlight the challenges of modelling epilepsy, in which the most obvious manifestation of the disorder, seizures, occurs only intermittently, possibly very rarely and often at times when the mice are not under direct observation. Over time, researchers have developed a number of ways in which to overcome these challenges, each with their own advantages and disadvantages. In this Review, we describe the genetics of epilepsy and the ways in which genetically altered mouse models have been used. We also discuss the use of induced models in which seizures are brought about by artificial stimulation to the brain of wild-type animals, and conclude with the ways these different approaches could be used to develop a wider range of anti-seizure medications that could benefit larger patient populations. Summary: This Review discusses the challenges of modelling epilepsy in mice, a condition in which the outward manifestation of the disorder appears only sporadically, and reviews possible solutions encompassing both genetic and induced models.
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Affiliation(s)
- Grant F Marshall
- Centre for Genomic and Experimental Medicine, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Alfredo Gonzalez-Sulser
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK.,Centre for Discovery Brain Sciences, 1 George Square, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Catherine M Abbott
- Centre for Genomic and Experimental Medicine, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK .,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK
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15
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Dhindsa RS, Zoghbi AW, Krizay DK, Vasavda C, Goldstein DB. A Transcriptome-Based Drug Discovery Paradigm for Neurodevelopmental Disorders. Ann Neurol 2021; 89:199-211. [PMID: 33159466 PMCID: PMC8122510 DOI: 10.1002/ana.25950] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 12/13/2022]
Abstract
Advances in genetic discoveries have created substantial opportunities for precision medicine in neurodevelopmental disorders. Many of the genes implicated in these diseases encode proteins that regulate gene expression, such as chromatin-associated proteins, transcription factors, and RNA-binding proteins. The identification of targeted therapeutics for individuals carrying mutations in these genes remains a challenge, as the encoded proteins can theoretically regulate thousands of downstream targets in a considerable number of cell types. Here, we propose the application of a drug discovery approach originally developed for cancer called "transcriptome reversal" for these neurodevelopmental disorders. This approach attempts to identify compounds that reverse gene-expression signatures associated with disease states. ANN NEUROL 2021;89:199-211.
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Affiliation(s)
- Ryan S. Dhindsa
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, USA
- Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Anthony W. Zoghbi
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, USA; New York State Psychiatric Institute, New York, USA
| | - Daniel K. Krizay
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, USA
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, USA
| | - Chirag Vasavda
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - David B. Goldstein
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, USA
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, USA
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16
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Systems biology reveals reprogramming of the S-nitroso-proteome in the cortical and striatal regions of mice during aging process. Sci Rep 2020; 10:13913. [PMID: 32807865 PMCID: PMC7431412 DOI: 10.1038/s41598-020-70383-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 07/28/2020] [Indexed: 12/26/2022] Open
Abstract
Cell aging depends on the rate of cumulative oxidative and nitrosative damage to DNA and proteins. Accumulated data indicate the involvement of protein S-nitrosylation (SNO), the nitric oxide (NO)-mediated posttranslational modification (PTM) of cysteine thiols, in different brain disorders. However, the changes and involvement of SNO in aging including the development of the organism from juvenile to adult state is still unknown. In this study, using the state-of-the-art mass spectrometry technology to identify S-nitrosylated proteins combined with large-scale computational biology, we tested the S-nitroso-proteome in juvenile and adult mice in both cortical and striatal regions. We found reprogramming of the S-nitroso-proteome in adult mice of both cortex and striatum regions. Significant biological processes and protein–protein clusters associated with synaptic and neuronal terms were enriched in adult mice. Extensive quantitative analysis revealed a large set of potentially pathological proteins that were significantly upregulated in adult mice. Our approach, combined with large scale computational biology allowed us to perform a system-level characterization and identification of the key proteins and biological processes that can serve as drug targets for aging and brain disorders in future studies.
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17
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Aimiuwu OV, Fowler AM, Sah M, Teoh JJ, Kanber A, Pyne NK, Petri S, Rosenthal-Weiss C, Yang M, Harper SQ, Frankel WN. RNAi-Based Gene Therapy Rescues Developmental and Epileptic Encephalopathy in a Genetic Mouse Model. Mol Ther 2020; 28:1706-1716. [PMID: 32353324 PMCID: PMC7335739 DOI: 10.1016/j.ymthe.2020.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/19/2020] [Accepted: 04/08/2020] [Indexed: 01/23/2023] Open
Abstract
Developmental and epileptic encephalopathy (DEE) associated with de novo variants in the gene encoding dynamin-1 (DNM1) is a severe debilitating disease with no pharmacological remedy. Like most genetic DEEs, the majority of DNM1 patients suffer from therapy-resistant seizures and comorbidities such as intellectual disability, developmental delay, and hypotonia. We tested RNAi gene therapy in the Dnm1 fitful mouse model of DEE using a Dnm1-targeted therapeutic microRNA delivered by a self-complementary adeno-associated virus vector. Untreated or control-injected fitful mice have growth delay, severe ataxia, and lethal tonic-clonic seizures by 3 weeks of age. These major impairments are mitigated following a single treatment in newborn mice, along with key underlying cellular features including gliosis, cell death, and aberrant neuronal metabolic activity typically associated with recurrent seizures. Our results underscore the potential for RNAi gene therapy to treat DNM1 disease and other genetic DEEs where treatment would require inhibition of the pathogenic gene product.
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Affiliation(s)
- Osasumwen V Aimiuwu
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Allison M Fowler
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Megha Sah
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jia Jie Teoh
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Ayla Kanber
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Nettie K Pyne
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Sabrina Petri
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Chana Rosenthal-Weiss
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Mu Yang
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Scott Q Harper
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43205, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine and Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA.
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18
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Bonnycastle K, Davenport EC, Cousin MA. Presynaptic dysfunction in neurodevelopmental disorders: Insights from the synaptic vesicle life cycle. J Neurochem 2020; 157:179-207. [PMID: 32378740 DOI: 10.1111/jnc.15035] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 12/11/2022]
Abstract
The activity-dependent fusion, retrieval and recycling of synaptic vesicles is essential for the maintenance of neurotransmission. Until relatively recently it was believed that most mutations in genes that were essential for this process would be incompatible with life, because of this fundamental role. However, an ever-expanding number of mutations in this very cohort of genes are being identified in individuals with neurodevelopmental disorders, including autism, intellectual disability and epilepsy. This article will summarize the current state of knowledge linking mutations in presynaptic genes to neurodevelopmental disorders by sequentially covering the various stages of the synaptic vesicle life cycle. It will also discuss how perturbations of specific stages within this recycling process could translate into human disease. Finally, it will also provide perspectives on the potential for future therapy that are targeted to presynaptic function.
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Affiliation(s)
- Katherine Bonnycastle
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
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19
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Kalia R, Frost A. Open and cut: allosteric motion and membrane fission by dynamin superfamily proteins. Mol Biol Cell 2020; 30:2097-2104. [PMID: 31365329 PMCID: PMC6743466 DOI: 10.1091/mbc.e16-10-0709] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells have evolved diverse protein-based machinery to reshape, cut, or fuse their membrane-delimited compartments. Dynamin superfamily proteins are principal components of this machinery and use their ability to hydrolyze GTP and to polymerize into helices and rings to achieve these goals. Nucleotide-binding, hydrolysis, and exchange reactions drive significant conformational changes across the dynamin family, and these changes alter the shape and stability of supramolecular dynamin oligomers, as well as the ability of dynamins to bind receptors and membranes. Mutations that interfere with the conformational repertoire of these enzymes, and hence with membrane fission, exist in several inherited human diseases. Here, we discuss insights from new x-ray crystal structures and cryo-EM reconstructions that have enabled us to infer some of the allosteric dynamics for these proteins. Together, these studies help us to understand how dynamins perform mechanical work, as well as how specific mutants of dynamin family proteins exhibit pathogenic properties.
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Affiliation(s)
- Raghav Kalia
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158.,Department of Biochemistry, University of Utah, Salt Lake City, UT 84132
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158.,Department of Biochemistry, University of Utah, Salt Lake City, UT 84132.,Chan-Zuckerberg Biohub, San Francisco, CA 94158
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Mizuguchi T, Nakashima M, Moey LH, Ch’ng GS, Khoo TB, Mitsuhashi S, Miyatake S, Takata A, Miyake N, Saitsu H, Matsumoto N. A novel homozygous truncating variant of NECAP1 in early infantile epileptic encephalopathy: the second case report of EIEE21. J Hum Genet 2019; 64:347-350. [DOI: 10.1038/s10038-018-0556-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 11/09/2022]
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Evaluating the pathogenic potential of genes with de novo variants in epileptic encephalopathies. Genet Med 2018; 21:17-27. [PMID: 29895856 PMCID: PMC6752304 DOI: 10.1038/s41436-018-0011-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 03/20/2018] [Indexed: 01/08/2023] Open
Abstract
Epileptic encephalopathies comprise a group of catastrophic epilepsies with heterogeneous genetic etiology. Although next-generation sequencing techniques can reveal a number of de novo variants in epileptic encephalopathies, evaluating the pathogenicity of these variants can be challenging. Determining the pathogenic potential of genes in epileptic encephalopathies is critical before evaluating the pathogenicity of variants identified in an individual. We reviewed de novo variants in epileptic encephalopathies, including their genotypes and functional consequences. We then evaluated the pathogenic potential of genes, with the following additional considerations: (1) recurrence of variants in unrelated cases, (2) information of previously defined phenotypes, and (3) data from genetic experimental studies. Genes related to epileptic encephalopathy revealed pathogenicity with distinct functional alterations, i.e., either a gain of function or loss of function in the majority; however, several genes warranted further study to confirm their pathogenic potential. Whether a gene was associated with distinct phenotype, the genotype (or functional alteration)-–phenotype correlation, and quantitative correlation between genetic impairment and phenotype severity were suggested to be specific evidence in determining the pathogenic role of genes. Data from epileptic encephalopathy-related genes would be helpful in outlining guidelines for evaluating the pathogenic potential of genes in other genetic disorders.
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Brereton E, Fassi E, Araujo GC, Dodd J, Telegrafi A, Pathak SJ, Shinawi M. Mutations in the PH Domain of DNM1 are associated with a nonepileptic phenotype characterized by developmental delay and neurobehavioral abnormalities. Mol Genet Genomic Med 2018; 6:294-300. [PMID: 29397573 PMCID: PMC5902389 DOI: 10.1002/mgg3.362] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 11/30/2022] Open
Abstract
Background Dynamin 1 is a protein involved in the synaptic vesicle cycle, which facilitates the exocytosis of neurotransmitters necessary for normal signaling and development in the central nervous system. Pathogenic variants in DNM1 have been implicated in global developmental delay (DD), severe intellectual disability (ID), and notably, epileptic encephalopathy. All previously reported DNM1 pathogenic variants causing this severe phenotype occur in the GTPase and Middle domains of the dynamin 1 protein. Methods We used whole‐exome sequencing to characterize the molecular basis of DD and autistic symptoms in two identical siblings. Results The twin siblings exhibit mild to moderate ID and autistic symptoms but no epileptic encephalopathy. Exome sequencing revealed a genetic variant, c.1603A>G (p.Lys535Glu), in the PH domain of dynamin 1. Previous in vitro studies showed that mutations at Lys535 inhibit endocytosis and impair PH loop binding to PIP2. Conclusions Our data suggest a previously undescribed milder phenotype associated with a missense genetic variant in the PH domain of dynamin 1.
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Affiliation(s)
- Emily Brereton
- Washington University School of Medicine, St. Louis, MO, USA
| | - Emily Fassi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Gabriel C Araujo
- Department of Psychology, St Louis Children's Hospital, St. Louis, MO, USA
| | - Jonathan Dodd
- Department of Psychology, St Louis Children's Hospital, St. Louis, MO, USA
| | | | - Sheel J Pathak
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Marwan Shinawi
- Washington University School of Medicine, St. Louis, MO, USA.,Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
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Harper CB, Mancini GMS, van Slegtenhorst M, Cousin MA. Altered synaptobrevin-II trafficking in neurons expressing a synaptophysin mutation associated with a severe neurodevelopmental disorder. Neurobiol Dis 2017; 108:298-306. [PMID: 28887151 PMCID: PMC5673032 DOI: 10.1016/j.nbd.2017.08.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/27/2017] [Accepted: 08/31/2017] [Indexed: 11/17/2022] Open
Abstract
Following exocytosis, synaptic vesicles (SVs) have to be reformed with the correct complement of proteins in the correct stoichiometry to ensure continued neurotransmission. Synaptophysin is a highly abundant, integral SV protein necessary for the efficient retrieval of the SV SNARE protein, synaptobrevin II (sybII). However the molecular mechanism underpinning synaptophysin-dependent sybII retrieval is still unclear. We recently identified a male patient with severe intellectual disability, hypotonia, epilepsy and callosal agenesis who has a point mutation in the juxtamembrane region of the fourth transmembrane domain of synaptophysin (T198I). This mutation had no effect on the activity-dependent retrieval of synaptophysin that was tagged with the genetically-encoded pH-sensitive reporter (pHluorin) in synaptophysin knockout hippocampal cultures. This suggested the mutant has no global effect on SV endocytosis, which was confirmed when retrieval of a different SV cargo (the glutamate transporter vGLUT1) was examined. However neurons expressing this T198I mutant did display impaired activity-dependent sybII retrieval, similar to that observed in synaptophysin knockout neurons. Interestingly this impairment did not result in an increased stranding of sybII at the plasma membrane. Screening of known human synaptophysin mutations revealed a similar presynaptic phenotype between T198I and a mutation found in X-linked intellectual disability. Thus this novel human synaptophysin mutation has revealed that aberrant retrieval and increased plasma membrane localisation of SV cargo can be decoupled in human disease.
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Affiliation(s)
- Callista B Harper
- Centre for Integrative Physiology, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom; Simonds Initiative for the Developing Brain, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus University Medical Center, 3015CN Rotterdam, The Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus University Medical Center, 3015CN Rotterdam, The Netherlands
| | - Michael A Cousin
- Centre for Integrative Physiology, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom; Simonds Initiative for the Developing Brain, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom.
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Myers CT, Stong N, Mountier EI, Helbig KL, Freytag S, Sullivan JE, Ben Zeev B, Nissenkorn A, Tzadok M, Heimer G, Shinde DN, Rezazadeh A, Regan BM, Oliver KL, Ernst ME, Lippa NC, Mulhern MS, Ren Z, Poduri A, Andrade DM, Bird LM, Bahlo M, Berkovic SF, Lowenstein DH, Scheffer IE, Sadleir LG, Goldstein DB, Mefford HC, Heinzen EL. De Novo Mutations in PPP3CA Cause Severe Neurodevelopmental Disease with Seizures. Am J Hum Genet 2017; 101:516-524. [PMID: 28942967 DOI: 10.1016/j.ajhg.2017.08.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/10/2017] [Indexed: 12/30/2022] Open
Abstract
Exome sequencing has readily enabled the discovery of the genetic mutations responsible for a wide range of diseases. This success has been particularly remarkable in the severe epilepsies and other neurodevelopmental diseases for which rare, often de novo, mutations play a significant role in disease risk. Despite significant progress, the high genetic heterogeneity of these disorders often requires large sample sizes to identify a critical mass of individuals with disease-causing mutations in a single gene. By pooling genetic findings across multiple studies, we have identified six individuals with severe developmental delay (6/6), refractory seizures (5/6), and similar dysmorphic features (3/6), each harboring a de novo mutation in PPP3CA. PPP3CA encodes the alpha isoform of a subunit of calcineurin. Calcineurin encodes a calcium- and calmodulin-dependent serine/threonine protein phosphatase that plays a role in a wide range of biological processes, including being a key regulator of synaptic vesicle recycling at nerve terminals. Five individuals with de novo PPP3CA mutations were identified among 4,760 trio probands with neurodevelopmental diseases; this is highly unlikely to occur by chance (p = 1.2 × 10-8) given the size and mutability of the gene. Additionally, a sixth individual with a de novo mutation in PPP3CA was connected to this study through GeneMatcher. Based on these findings, we securely implicate PPP3CA in early-onset refractory epilepsy and further support the emerging role for synaptic dysregulation in epilepsy.
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Affiliation(s)
- Candace T Myers
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Nicholas Stong
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Emily I Mountier
- Department of Paediatrics and Child Health, University of Otago, Wellington 6242, New Zealand
| | | | - Saskia Freytag
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, VIC 3050, Australia
| | - Joseph E Sullivan
- Department of Neurology & Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Bruria Ben Zeev
- Sheba Medical Center, Ramat Gan, Israel, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Andreea Nissenkorn
- Sheba Medical Center, Ramat Gan, Israel, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Michal Tzadok
- Sheba Medical Center, Ramat Gan, Israel, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Gali Heimer
- Sheba Medical Center, Ramat Gan, Israel, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | | | - Arezoo Rezazadeh
- Division of Neurology, Epilepsy Genetics Research Program, Toronto Western Hospital, Krembil Neuroscience Centre, University of Toronto, Toronto, ON M5T 2S8, Canada
| | - Brigid M Regan
- Division of Neurology, Epilepsy Genetics Research Program, Toronto Western Hospital, Krembil Neuroscience Centre, University of Toronto, Toronto, ON M5T 2S8, Canada
| | - Karen L Oliver
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Epilepsy Research Centre, Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, VIC 3084, Australia
| | - Michelle E Ernst
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Natalie C Lippa
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Maureen S Mulhern
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Zhong Ren
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital and Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Danielle M Andrade
- Division of Neurology, Epilepsy Genetics Research Program, Toronto Western Hospital, Krembil Neuroscience Centre, University of Toronto, Toronto, ON M5T 2S8, Canada
| | - Lynne M Bird
- Department of Pediatrics, University of California, San Diego, San Diego, CA 92037, USA; Rady Children's Hospital, San Diego, CA 92037, USA
| | - Melanie Bahlo
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, VIC 3050, Australia
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, VIC 3084, Australia
| | - Daniel H Lowenstein
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, VIC 3084, Australia; Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3010, Australia; Department of Paediatrics, Royal Children's Hospital, The University of Melbourne, Parkville, VIC 3050, Australia
| | - Lynette G Sadleir
- Department of Paediatrics and Child Health, University of Otago, Wellington 6242, New Zealand
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA.
| | - Erin L Heinzen
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA.
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Shimojima K, Okamoto N, Goel H, Ondo Y, Yamamoto T. Familial 9q33q34 microduplication in siblings with developmental disorders and macrocephaly. Eur J Med Genet 2017; 60:650-654. [PMID: 28899818 DOI: 10.1016/j.ejmg.2017.08.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/28/2017] [Accepted: 08/29/2017] [Indexed: 10/18/2022]
Abstract
Because several genes responsible for epileptic encephalopathy are located on the 9q33q34 region, patients with chromosomal deletions of this region often show intractable epilepsy and neurodevelopmental disability. Contrary to these findings, chromosomal duplications of this region have never been reported previously. We identified a first case of 9q33q34 microduplications in siblings associated with developmental disorders and macrocephaly. Their mother was a mosaic carrier of this duplication. Duplicated regions involved STXBP1; the gene related to epileptic encephalopathy. Neurological features including developmental delay and macrocephaly observed in the present siblings may be derived from the extra-copy of STXBP1.
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Affiliation(s)
- Keiko Shimojima
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Himanshu Goel
- School of Medicine and Public Health, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Yumiko Ondo
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
| | - Toshiyuki Yamamoto
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan.
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Need AC, Goldstein DB. Neuropsychiatric genomics in precision medicine: diagnostics, gene discovery, and translation. DIALOGUES IN CLINICAL NEUROSCIENCE 2017. [PMID: 27757059 PMCID: PMC5067142 DOI: 10.31887/dcns.2016.18.3/aneed] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Only a few years after its development, next-generation sequencing is rapidly becoming an essential part of clinical care for patients with serious neurological conditions, especially in the diagnosis of early-onset and severe presentations. Beyond this diagnostic role, there has been an explosion in definitive gene discovery in a range of neuropsychiatric diseases. This is providing new pointers to underlying disease biology and is beginning to outline a new framework for genetic stratification of neuropsychiatric disease, with clear relevance to both individual treatment optimization and clinical trial design. Here, we outline these developments and chart the expected impact on the treatment of neurological, neurodevelopmental, and psychiatric disease.
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Affiliation(s)
- Anna C Need
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, W12 ONN, UK
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY, 10032, USA
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Abstract
Epileptic encephalopathies account for a large proportion of the intractable early-onset epilepsies and are characterized by frequent seizures and poor developmental outcome. The epileptic encephalopathies can be loosely divided into two related groups of named syndromes. The first comprises epilepsies where continuous EEG changes directly result in cognitive and developmental dysfunction. The second includes patients where cognitive impairment is present at seizure onset and is due to the underlying etiology but the epileptic activity may then worsen the cognitive abilities over time. Recent, large-scale exome studies have begun to establish the genetic architecture of the epileptic encephalopathies, resulting in a re-consideration of the boundaries of these named syndromes. The emergence of this genetic architecture has lead to three main pathophysiological concepts to provide a mechanistic framework for these disorders. In this article, we will review the classic syndromes, the most significant genetic findings, and relate both to the pathophysiological understanding of epileptic encephalopathies.
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28
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von Spiczak S, Helbig KL, Shinde DN, Huether R, Pendziwiat M, Lourenço C, Nunes ME, Sarco DP, Kaplan RA, Dlugos DJ, Kirsch H, Slavotinek A, Cilio MR, Cervenka MC, Cohen JS, McClellan R, Fatemi A, Yuen A, Sagawa Y, Littlejohn R, McLean SD, Hernandez-Hernandez L, Maher B, Møller RS, Palmer E, Lawson JA, Campbell CA, Joshi CN, Kolbe DL, Hollingsworth G, Neubauer BA, Muhle H, Stephani U, Scheffer IE, Pena SDJ, Sisodiya SM, Helbig I. DNM1 encephalopathy: A new disease of vesicle fission. Neurology 2017; 89:385-394. [PMID: 28667181 PMCID: PMC5574673 DOI: 10.1212/wnl.0000000000004152] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/26/2017] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To evaluate the phenotypic spectrum caused by mutations in dynamin 1 (DNM1), encoding the presynaptic protein DNM1, and to investigate possible genotype-phenotype correlations and predicted functional consequences based on structural modeling. METHODS We reviewed phenotypic data of 21 patients (7 previously published) with DNM1 mutations. We compared mutation data to known functional data and undertook biomolecular modeling to assess the effect of the mutations on protein function. RESULTS We identified 19 patients with de novo mutations in DNM1 and a sibling pair who had an inherited mutation from a mosaic parent. Seven patients (33.3%) carried the recurrent p.Arg237Trp mutation. A common phenotype emerged that included severe to profound intellectual disability and muscular hypotonia in all patients and an epilepsy characterized by infantile spasms in 16 of 21 patients, frequently evolving into Lennox-Gastaut syndrome. Two patients had profound global developmental delay without seizures. In addition, we describe a single patient with normal development before the onset of a catastrophic epilepsy, consistent with febrile infection-related epilepsy syndrome at 4 years. All mutations cluster within the GTPase or middle domains, and structural modeling and existing functional data suggest a dominant-negative effect on DMN1 function. CONCLUSIONS The phenotypic spectrum of DNM1-related encephalopathy is relatively homogeneous, in contrast to many other genetic epilepsies. Up to one-third of patients carry the recurrent p.Arg237Trp variant, which is now one of the most common recurrent variants in epileptic encephalopathies identified to date. Given the predicted dominant-negative mechanism of this mutation, this variant presents a prime target for therapeutic intervention.
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Affiliation(s)
| | | | | | - Robert Huether
- Author affiliations are provided at the end of the article
| | | | | | - Mark E Nunes
- Author affiliations are provided at the end of the article
| | - Dean P Sarco
- Author affiliations are provided at the end of the article
| | | | | | - Heidi Kirsch
- Author affiliations are provided at the end of the article
| | | | - Maria R Cilio
- Author affiliations are provided at the end of the article
| | | | - Julie S Cohen
- Author affiliations are provided at the end of the article
| | | | - Ali Fatemi
- Author affiliations are provided at the end of the article
| | - Amy Yuen
- Author affiliations are provided at the end of the article
| | - Yoshimi Sagawa
- Author affiliations are provided at the end of the article
| | | | - Scott D McLean
- Author affiliations are provided at the end of the article
| | | | - Bridget Maher
- Author affiliations are provided at the end of the article
| | - Rikke S Møller
- Author affiliations are provided at the end of the article
| | | | - John A Lawson
- Author affiliations are provided at the end of the article
| | | | | | - Diana L Kolbe
- Author affiliations are provided at the end of the article
| | | | | | - Hiltrud Muhle
- Author affiliations are provided at the end of the article
| | | | | | | | | | - Ingo Helbig
- Author affiliations are provided at the end of the article.
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Li YC, Kavalali ET. Synaptic Vesicle-Recycling Machinery Components as Potential Therapeutic Targets. Pharmacol Rev 2017; 69:141-160. [PMID: 28265000 DOI: 10.1124/pr.116.013342] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Presynaptic nerve terminals are highly specialized vesicle-trafficking machines. Neurotransmitter release from these terminals is sustained by constant local recycling of synaptic vesicles independent from the neuronal cell body. This independence places significant constraints on maintenance of synaptic protein complexes and scaffolds. Key events during the synaptic vesicle cycle-such as exocytosis and endocytosis-require formation and disassembly of protein complexes. This extremely dynamic environment poses unique challenges for proteostasis at synaptic terminals. Therefore, it is not surprising that subtle alterations in synaptic vesicle cycle-associated proteins directly or indirectly contribute to pathophysiology seen in several neurologic and psychiatric diseases. In contrast to the increasing number of examples in which presynaptic dysfunction causes neurologic symptoms or cognitive deficits associated with multiple brain disorders, synaptic vesicle-recycling machinery remains an underexplored drug target. In addition, irrespective of the involvement of presynaptic function in the disease process, presynaptic machinery may also prove to be a viable therapeutic target because subtle alterations in the neurotransmitter release may counter disease mechanisms, correct, or compensate for synaptic communication deficits without the need to interfere with postsynaptic receptor signaling. In this article, we will overview critical properties of presynaptic release machinery to help elucidate novel presynaptic avenues for the development of therapeutic strategies against neurologic and neuropsychiatric disorders.
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Affiliation(s)
- Ying C Li
- Departments of Neuroscience (Y.C.L., E.T.K.) and Physiology (E.T.K.), University of Texas Southwestern Medical Center, Dallas, Texas
| | - Ege T Kavalali
- Departments of Neuroscience (Y.C.L., E.T.K.) and Physiology (E.T.K.), University of Texas Southwestern Medical Center, Dallas, Texas
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Summaries of plenary and selected symposia sessions at the XXIV World Congress of Psychiatric Genetics; Jerusalem, Israel; 30 October 2016-3 November 2016. Psychiatr Genet 2017; 27:41-53. [PMID: 28212207 DOI: 10.1097/ypg.0000000000000167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The XXII World Congress of Psychiatric Genetics, sponsored by the International Society of Psychiatric Genetics, took place in Jerusalem, Israel, from 30 October 2016 to 3 November 2016. A total of 372 participants gathered to discuss the latest findings in the field. The following report was written by early career investigator travel awardees, and student and postdoctoral attendees. Each was assigned one or more sessions as a rapporteur. This manuscript represents topics covered in most, but not all of the presentations during the conference, and contains some of the major notable new findings reported.
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Abstract
The epileptic encephalopathies are severe and often treatment-resistant conditions that are associated with a progressive disturbance of brain function, resulting in a broad range of neurological and non-neurological comorbidities. The concept of epileptic encephalopathies entails that the encephalopathy aspect of the overall condition is primarily driven by the epileptic activity of the disease, which often manifests as specific and pathological features on the electroencephalogram. Genetic factors in epileptic encephalopathies are increasingly recognized. As of 2016, more than 30 genes have been securely implicated as causative genes for genetic epileptic encephalopathies. Even though the traditional concept of epileptic encephalopathies entails that the progressive disturbance of brain dysfunction is primarily due to the abnormal hypersynchronous activity that underlies the seizure disorders, this strict concept rarely holds true for patients with identified genetic etiologies. More commonly, an underlying genetic etiology is thought to predispose both to the neurodevelopmental comorbidities and to the seizure phenotype with a complex interaction between both. In this chapter, we will elucidate to what extent neurodegeneration rather than epilepsy-related regression is a feature of the common epileptic encephalopathies, drawing parallels between two relatively separate fields of neurogenetic research.
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Han C, Alkhater R, Froukh T, Minassian AG, Galati M, Liu RH, Fotouhi M, Sommerfeld J, Alfrook AJ, Marshall C, Walker S, Bauer P, Scherer SW, Riess O, Buchert R, Minassian BA, McPherson PS. Epileptic Encephalopathy Caused by Mutations in the Guanine Nucleotide Exchange Factor DENND5A. Am J Hum Genet 2016; 99:1359-1367. [PMID: 27866705 DOI: 10.1016/j.ajhg.2016.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/10/2016] [Indexed: 12/21/2022] Open
Abstract
Epileptic encephalopathies are a catastrophic group of epilepsies characterized by refractory seizures and cognitive arrest, often resulting from abnormal brain development. Here, we have identified an epileptic encephalopathy additionally featuring cerebral calcifications and coarse facial features caused by recessive loss-of-function mutations in DENND5A. DENND5A contains a DENN domain, an evolutionarily ancient enzymatic module conferring guanine nucleotide exchange factor (GEF) activity to multiple proteins serving as GEFs for Rabs, which are key regulators of membrane trafficking. DENND5A is detected predominantly in neuronal tissues, and its highest levels occur during development. Knockdown of DENND5A leads to striking alterations in neuronal development. Mechanistically, these changes appear to result from upregulation of neurotrophin receptors, leading to enhanced downstream signaling. Thus, we have identified a link between a DENN domain protein and neuronal development, dysfunction of which is responsible for a form of epileptic encephalopathy.
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Affiliation(s)
- Chanshuai Han
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Reem Alkhater
- Johns Hopkins Aramco Healthcare, Dhahran 34465, Saudi Arabia
| | - Tawfiq Froukh
- Department of Biotechnology and Genetic Engineering, Faculty of Science, Philadelphia University, Amman 11118, Jordan
| | - Arakel G Minassian
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Melissa Galati
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Rui Han Liu
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Maryam Fotouhi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Julia Sommerfeld
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | | | - Christian Marshall
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Susan Walker
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Peter Bauer
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | - Stephen W Scherer
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics and McLaughlin Centre, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | - Rebecca Buchert
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | - Berge A Minassian
- Program in Genetics and Genome Biology, Department of Pediatrics (Neurology), Hospital for Sick Children and University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
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Need AC. Neuropsychiatric genomics in precision medicine: diagnostics, gene discovery, and translation. DIALOGUES IN CLINICAL NEUROSCIENCE 2016; 18:237-252. [PMID: 27757059 PMCID: PMC5067142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Only a few years after its development, next-generation sequencing is rapidly becoming an essential part of clinical care for patients with serious neurological conditions, especially in the diagnosis of early-onset and severe presentations. Beyond this diagnostic role, there has been an explosion in definitive gene discovery in a range of neuropsychiatric diseases. This is providing new pointers to underlying disease biology and is beginning to outline a new framework for genetic stratification of neuropsychiatric disease, with clear relevance to both individual treatment optimization and clinical trial design. Here, we outline these developments and chart the expected impact on the treatment of neurological, neurodevelopmental, and psychiatric disease.
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Affiliation(s)
- Anna C. Need
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, W12 ONN, UK
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Dynamin 1 isoform roles in a mouse model of severe childhood epileptic encephalopathy. Neurobiol Dis 2016; 95:1-11. [PMID: 27363778 DOI: 10.1016/j.nbd.2016.06.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/23/2016] [Accepted: 06/26/2016] [Indexed: 01/05/2023] Open
Abstract
Dynamin 1 is a large neuron-specific GTPase involved in the endocytosis and recycling of pre-synaptic membranes and synaptic vesicles. Mutations in the gene encoding dynamin 1 (DNM1) underlie two epileptic encephalopathy syndromes, Lennox-Gastaut Syndrome and Infantile Spasms. Mice homozygous for the Dnm1 "fitful" mutation, a non-synonymous coding variant in an alternatively spliced exon of Dnm1 (exon 10a; isoform designation: Dnm1a(Ftfl)) have an epileptic encephalopathy-like disorder including lethal early onset seizures, locomotor and neurosensory deficits. Although fitful heterozygotes have milder recurrent seizures later in life, suggesting an additive or semi-dominant mechanism, the molecular etiology must also consider the fact that Dnm1a(Ftfl) exerts a dominant negative effect on endocytosis in vitro. Another complication is that the fitful mutation induces alterations in the relative abundance of Dnm1 splice variants; mutants have a downregulation of Dnm1a and an upregulation of Dnm1b, changes which may contribute to the epileptic pathology. To examine whether Dnm1a loss of function, Dnm1a(Ftfl) dominance or compensation by Dnm1b is the most critical for severe seizures, we studied alternate isoform-specific mutant mice. Mice lacking Dnm1 exon 10a or Dnm1 exon 10b have neither spontaneous seizures nor other overt abnormalities, suggesting that in normal conditions the major role of each isoform is redundant. However, in the presence of Dnm1a(Ftfl) only exon 10a deleted mice experience severe seizures. These results reveal functional differences between Dnm1a and Dnm1b isoforms in the presence of a challenge, i.e. toxic Dnm1(Ftfl), while reinforcing its effect explicitly in this model of severe pediatric epilepsy.
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Dhindsa RS, Goldstein DB. Genetic Discoveries Drive Molecular Analyses and Targeted Therapeutic Options in the Epilepsies. Curr Neurol Neurosci Rep 2016; 15:70. [PMID: 26319171 DOI: 10.1007/s11910-015-0587-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Epilepsy is a serious neurological disease with substantial genetic contribution. We have recently made major advances in understanding the genetics and etiology of the epilepsies. However, current antiepileptic drugs are ineffective in nearly one third of patients. Most of these drugs were developed without knowledge of the underlying causes of the epilepsy to be treated; thus, it seems reasonable to assume that further improvements require a deeper understanding of epilepsy pathophysiology. Although once the rate-limiting step, gene discovery is now occurring at an unprecedented rapid rate, especially in the epileptic encephalopathies. However, to place these genetic findings in a biological context and discover treatment options for patients, we must focus on developing an efficient framework for functional evaluation of the mutations that cause epilepsy. In this review, we discuss guidelines for gene discovery, emerging functional assays and models, and novel therapeutics to highlight the developing framework of precision medicine in the epilepsies.
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Affiliation(s)
- Ryan S Dhindsa
- Institute for Genomic Medicine, Columbia University, Hammer Building, 701 West 168th Street, Box 149, New York, NY, 10032, USA,
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The DyNaMics of Excitation and Inhibition Govern Epileptic Encephalopathies and Their Comorbidities. Epilepsy Curr 2016; 16:172-3. [DOI: 10.5698/1535-7511-16.3.172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Moustaq L, Smaczynska-de Rooij II, Palmer SE, Marklew CJ, Ayscough KR. Insights into dynamin-associated disorders through analysis of equivalent mutations in the yeast dynamin Vps1. MICROBIAL CELL 2016; 3:147-158. [PMID: 28357347 PMCID: PMC5349089 DOI: 10.15698/mic2016.04.490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The dynamins represent a superfamily of proteins that have been shown to function
in a wide range of membrane fusion and fission events. An increasing number of
mutations in the human classical dynamins, Dyn-1 and Dyn-2 has been reported,
with diseases caused by these changes ranging from Charcot-Marie-Tooth disorder
to epileptic encephalopathies. The budding yeast, Saccharomyces
cerevisiae expresses a single dynamin-related protein that
functions in membrane trafficking, and is considered to play a similar role to
Dyn-1 and Dyn-2 during scission of endocytic vesicles at the plasma membrane.
Large parts of the dynamin protein are highly conserved across species and this
has enabled us in this study to select a number of disease causing mutations and
to generate equivalent mutations in Vps1. We have then studied these mutants
using both cellular and biochemical assays to ascertain functions of the protein
that have been affected by the changes. Specifically, we demonstrate that the
Vps1-G397R mutation (Dyn-2 G358R) disrupts protein oligomerization, Vps1-A447T
(Dyn-1 A408T) affects the scission stage of endocytosis, while Vps1-R298L (Dyn-1
R256L) affects lipid binding specificity and possibly an early stage in
endocytosis. Overall, we consider that the yeast model will potentially provide
an avenue for rapid analysis of new dynamin mutations in order to understand the
underlying mechanisms that they disrupt
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Affiliation(s)
- Laila Moustaq
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | | | - Sarah E Palmer
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | | | - Kathryn R Ayscough
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
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A roadmap for precision medicine in the epilepsies. Lancet Neurol 2015; 14:1219-28. [PMID: 26416172 PMCID: PMC4663979 DOI: 10.1016/s1474-4422(15)00199-4] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/20/2015] [Accepted: 07/27/2015] [Indexed: 12/18/2022]
Abstract
Technological advances have paved the way for accelerated genomic discovery and are bringing precision medicine clearly into view. Epilepsy research in particular is well suited to serve as a model for the development and deployment of targeted therapeutics in precision medicine because of the rapidly expanding genetic knowledge base in epilepsy, the availability of good in-vitro and in-vivo model systems to efficiently study the biological consequences of genetic mutations, the ability to turn these models into effective drug-screening platforms, and the establishment of collaborative research groups. Moving forward, it is crucial that these collaborations are strengthened, particularly through integrated research platforms, to provide robust analyses both for accurate personal genome analysis and gene and drug discovery. Similarly, the implementation of clinical trial networks will allow the expansion of patient sample populations with genetically defined epilepsy so that drug discovery can be translated into clinical practice.
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Affiliation(s)
- Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT
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Asinof SK, Sukoff Rizzo SJ, Buckley AR, Beyer BJ, Letts VA, Frankel WN, Boumil RM. Independent Neuronal Origin of Seizures and Behavioral Comorbidities in an Animal Model of a Severe Childhood Genetic Epileptic Encephalopathy. PLoS Genet 2015; 11:e1005347. [PMID: 26125563 PMCID: PMC4488318 DOI: 10.1371/journal.pgen.1005347] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/09/2015] [Indexed: 01/01/2023] Open
Abstract
The childhood epileptic encephalopathies (EE’s) are seizure disorders that broadly impact development including cognitive, sensory and motor progress with severe consequences and comorbidities. Recently, mutations in DNM1 (dynamin 1) have been implicated in two EE syndromes, Lennox-Gastaut Syndrome and Infantile Spasms. Dnm1 encodes dynamin 1, a large multimeric GTPase necessary for activity-dependent membrane recycling in neurons, including synaptic vesicle endocytosis. Dnm1Ftfl or “fitful” mice carry a spontaneous mutation in the mouse ortholog of DNM1 and recapitulate many of the disease features associated with human DNM1 patients, providing a relevant disease model of human EE’s. In order to examine the cellular etiology of seizures and behavioral and neurological comorbidities, we engineered a conditional Dnm1Ftfl mouse model of DNM1 EE. Observations of Dnm1Ftfl/flox mice in combination with various neuronal subpopulation specific cre strains demonstrate unique seizure phenotypes and clear separation of major neurobehavioral comorbidities from severe seizures associated with the germline model. This demonstration of pleiotropy suggests that treating seizures per se may not prevent severe comorbidity observed in EE associated with dynamin-1 mutations, and is likely to have implications for other genetic forms of EE. Childhood epilepsy syndromes, such as the early epileptic encephalopathies (EE’s) encompass seizure disorders that manifest early and negatively impact or completely block developmental progression. Recently, mutations in DNM1 (dynamin 1) have been implicated in two EE syndromes, Lennox-Gastaut Syndrome and Infantile Spasms. Dynamin 1 is a large multimeric protein that is critical for electro-chemical communication between neurons. To understand the relationship between severe seizures and the cognitive and behavioral developmental outcomes in DNM1 patients, we focus on “fitful” mice that carry a mutation in the dynamin 1 gene. Fitful mice have an EE disorder that is highly reminiscent of the documented human patients. Here, we describe genetic manipulations in the mice that allow us to determine that the seizure activity has independent cellular origins from the developmental and behavioral consequences. This separation confirms that the seizures do not cause the severe developmental delay and abnormal behaviors in this animal model and further suggests that any treatments aimed at controlling the seizures per se may not be effective for some of the most acute neurobehavioral symptoms in these patients.
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Affiliation(s)
- Samuel K. Asinof
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Alexandra R. Buckley
- Biomedical Sciences Graduate Program, University of California, San Diego, San Diego, California, United States of America
| | - Barbara J. Beyer
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Verity A. Letts
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wayne N. Frankel
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Rebecca M. Boumil
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- * E-mail:
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