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Nowacka A, Getz AM, Bessa-Neto D, Choquet D. Activity-dependent diffusion trapping of AMPA receptors as a key step for expression of early LTP. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230220. [PMID: 38853553 DOI: 10.1098/rstb.2023.0220] [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: 02/24/2024] [Accepted: 04/11/2024] [Indexed: 06/11/2024] Open
Abstract
This review focuses on the activity-dependent diffusion trapping of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as a crucial mechanism for the expression of early long-term potentiation (LTP), a process central to learning and memory. Despite decades of research, the precise mechanisms by which LTP induction leads to an increase in AMPAR responses at synapses have been elusive. We review the different hypotheses that have been put forward to explain the increased AMPAR responsiveness during LTP. We discuss the dynamic nature of AMPAR complexes, including their constant turnover and activity-dependent modifications that affect their synaptic accumulation. We highlight a hypothesis suggesting that AMPARs are diffusively trapped at synapses through activity-dependent interactions with protein-based binding slots in the post-synaptic density (PSD), offering a potential explanation for the increased synaptic strength during LTP. Furthermore, we outline the challenges still to be addressed before we fully understand the functional roles and molecular mechanisms of AMPAR dynamic nanoscale organization in LTP. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Agata Nowacka
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297 , Bordeaux F-33000, France
| | - Angela M Getz
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297 , Bordeaux F-33000, France
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4 , Bordeaux F-33000, France
| | - Diogo Bessa-Neto
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297 , Bordeaux F-33000, France
| | - Daniel Choquet
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297 , Bordeaux F-33000, France
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4 , Bordeaux F-33000, France
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2
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Sumathipala SH, Khan S, Kozol RA, Araki Y, Syed S, Huganir RL, Dallman JE. Context-dependent hyperactivity in syngap1a and syngap1b zebrafish models of SYNGAP1-related disorder. Front Mol Neurosci 2024; 17:1401746. [PMID: 39050824 PMCID: PMC11266194 DOI: 10.3389/fnmol.2024.1401746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 06/04/2024] [Indexed: 07/27/2024] Open
Abstract
Background and aims SYNGAP1-related disorder (SYNGAP1-RD) is a prevalent genetic form of Autism Spectrum Disorder and Intellectual Disability (ASD/ID) and is caused by de novo or inherited mutations in one copy of the SYNGAP1 gene. In addition to ASD/ID, SYNGAP1 disorder is associated with comorbid symptoms including treatment-resistant-epilepsy, sleep disturbances, and gastrointestinal distress. Mechanistic links between these diverse symptoms and SYNGAP1 variants remain obscure, therefore, our goal was to generate a zebrafish model in which this range of symptoms can be studied. Methods We used CRISPR/Cas9 to introduce frameshift mutations in the syngap1a and syngap1b zebrafish duplicates (syngap1ab) and validated these stable models for Syngap1 loss-of-function. Because SYNGAP1 is extensively spliced, we mapped splice variants to the two zebrafish syngap1a and b genes and identified mammalian-like isoforms. We then quantified locomotory behaviors in zebrafish syngap1ab larvae under three conditions that normally evoke different arousal states in wild-type larvae: aversive, high-arousal acoustic, medium-arousal dark, and low-arousal light stimuli. Results We show that CRISPR/Cas9 indels in zebrafish syngap1a and syngap1b produced loss-of-function alleles at RNA and protein levels. Our analyses of zebrafish Syngap1 isoforms showed that, as in mammals, zebrafish Syngap1 N- and C-termini are extensively spliced. We identified a zebrafish syngap1 α1-like variant that maps exclusively to the syngap1b gene. Quantifying locomotor behaviors showed that syngap1ab mutant larvae are hyperactive compared to wild-type but to differing degrees depending on the stimulus. Hyperactivity was most pronounced in low arousal settings, and hyperactivity was proportional to the number of mutant syngap1 alleles. Limitations Syngap1 loss-of-function mutations produce relatively subtle phenotypes in zebrafish compared to mammals. For example, while mouse Syngap1 homozygotes die at birth, zebrafish syngap1ab-/- survive to adulthood and are fertile, thus some aspects of symptoms in people with SYNGAP1-Related Disorder are not likely to be reflected in zebrafish. Conclusion Our data support mutations in zebrafish syngap1ab as causal for hyperactivity associated with elevated arousal that is especially pronounced in low-arousal environments.
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Affiliation(s)
- Sureni H. Sumathipala
- Department of Biology, University of Miami, Coral Gables, FL, United States
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, United States
| | - Suha Khan
- Department of Biology, University of Miami, Coral Gables, FL, United States
| | - Robert A. Kozol
- Department of Biology, University of Miami, Coral Gables, FL, United States
- Department of Biological Sciences, St. John’s University, Queens, NY, United States
| | - Yoichi Araki
- Department of Neuroscience and Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sheyum Syed
- Department of Physics, University of Miami, Coral Gables, FL, United States
| | - Richard L. Huganir
- Department of Neuroscience and Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Julia E. Dallman
- Department of Biology, University of Miami, Coral Gables, FL, United States
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Wiltrout K, Brimble E, Poduri A. Comprehensive phenotypes of patients with SYNGAP1-related disorder reveals high rates of epilepsy and autism. Epilepsia 2024; 65:1428-1438. [PMID: 38470175 DOI: 10.1111/epi.17913] [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: 05/31/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 03/13/2024]
Abstract
OBJECTIVE To delineate the comprehensive phenotypic spectrum of SYNGAP1-related disorder in a large patient cohort aggregated through a digital registry. METHODS We obtained de-identified patient data from an online registry. Data were extracted from uploaded medical records. We reclassified all SYNGAP1 variants using American College of Medical Genetics criteria and included patients with pathogenic/likely pathogenic (P/LP) single nucleotide variants or microdeletions incorporating SYNGAP1. We analyzed neurodevelopmental phenotypes, including epilepsy, intellectual disability (ID), autism spectrum disorder (ASD), behavioral disorders, and gait dysfunction for all patients with respect to variant type and location within the SynGAP1 protein. RESULTS We identified 147 patients (50% male, median age 8 years) with P/LP SYNGAP1 variants from 151 individuals with data available through the database. One hundred nine were truncating variants and 22 were missense. All patients were diagnosed with global developmental delay (GDD) and/or ID, and 123 patients (84%) were diagnosed with epilepsy. Of those with epilepsy, 73% of patients had GDD diagnosed before epilepsy was diagnosed. Other prominent features included autistic traits (n = 100, 68%), behavioral problems (n = 100, 68%), sleep problems (n = 90, 61%), anxiety (n = 35, 24%), ataxia or abnormal gait (n = 69, 47%), sensory problems (n = 32, 22%), and feeding difficulties (n = 69, 47%). Behavioral problems were more likely in those patients diagnosed with anxiety (odds ratio [OR] 3.6, p = .014) and sleep problems (OR 2.41, p = .015) but not necessarily those with autistic traits. Patients with variants in exons 1-4 were more likely to have the ability to speak in phrases vs those with variants in exons 5-19, and epilepsy occurred less frequently in patients with variants in the SH3 binding motif. SIGNIFICANCE We demonstrate that the data obtained from a digital registry recapitulate earlier but smaller studies of SYNGAP1-related disorder and add additional genotype-phenotype relationships, validating the use of the digital registry. Access to data through digital registries broadens the possibilities for efficient data collection in rare diseases.
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Affiliation(s)
- Kimberly Wiltrout
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | | | - Annapurna Poduri
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Ribeiro-Constante J, Tristán-Noguero A, Martínez Calvo FF, Ibañez-Mico S, Peña Segura JL, Ramos-Fernández JM, Moyano Chicano MDC, Camino León R, Soto Insuga V, González Alguacil E, Valera Dávila C, Fernández-Jaén A, Plans L, Camacho A, Visa-Reñé N, Martin-Tamayo Blázquez MDP, Paredes-Carmona F, Marti-Carrera I, Hernández-Fabián A, Tomas Davi M, Sanchez MC, Herraiz LC, Pita PF, Gonzalez TB, O'Callaghan M, Iglesias Santa Polonia FF, Cazorla MR, Ferrando Lucas MT, González-Meneses A, Sala-Coromina J, Macaya A, Lasa-Aranzasti A, Cueto-González AM, Valera Párraga F, Campistol Plana J, Serrano M, Alonso X, Del Castillo-Berges D, Schwartz-Palleja M, Illescas S, Ramírez Camacho A, Sans Capdevila O, García-Cazorla A, Bayés À, Alonso-Colmenero I. Developmental outcome of electroencephalographic findings in SYNGAP1 encephalopathy. Front Cell Dev Biol 2024; 12:1321282. [PMID: 38505260 PMCID: PMC10948473 DOI: 10.3389/fcell.2024.1321282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 01/22/2024] [Indexed: 03/21/2024] Open
Abstract
SYNGAP1 haploinsufficiency results in a developmental and epileptic encephalopathy (DEE) causing generalized epilepsies accompanied by a spectrum of neurodevelopmental symptoms. Concerning interictal epileptiform discharges (IEDs) in electroencephalograms (EEG), potential biomarkers have been postulated, including changes in background activity, fixation-off sensitivity (FOS) or eye closure sensitivity (ECS). In this study we clinically evaluate a new cohort of 36 SYNGAP1-DEE individuals. Standardized questionnaires were employed to collect clinical, electroencephalographic and genetic data. We investigated electroencephalographic findings, focusing on the cortical distribution of interictal abnormalities and their changes with age. Among the 36 SYNGAP1-DEE cases 18 presented variants in the SYNGAP1 gene that had never been previously reported. The mean age of diagnosis was 8 years and 8 months, ranging from 2 to 17 years, with 55.9% being male. All subjects had global neurodevelopmental/language delay and behavioral abnormalities; 83.3% had moderate to profound intellectual disability (ID), 91.7% displayed autistic traits, 73% experienced sleep disorders and 86.1% suffered from epileptic seizures, mainly eyelid myoclonia with absences (55.3%). A total of 63 VEEGs were revised, observing a worsening of certain EEG findings with increasing age. A disorganized background was observed in all age ranges, yet this was more common among older cases. The main IEDs were bilateral synchronous and asynchronous posterior discharges, accounting for ≥50% in all age ranges. Generalized alterations with maximum amplitude in the anterior region showed as the second most frequent IED (≥15% in all age ranges) and were also more common with increasing age. Finally, diffuse fast activity was much more prevalent in cases with 6 years or older. To the best of our knowledge, this is the first study to analyze EEG features across different age groups, revealing an increase in interictal abnormalities over infancy and adolescence. Our findings suggest that SYNGAP1 haploinsufficiency has complex effects in human brain development, some of which might unravel at different developmental stages. Furthermore, they highlight the potential of baseline EEG to identify candidate biomarkers and the importance of natural history studies to develop specialized therapies and clinical trials.
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Affiliation(s)
| | - Alba Tristán-Noguero
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
- Molecular Physiology of the Synapse Laboratory, Institut de Recerca Sant Pau (IR Sant Pau), Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | | | - José Luis Peña Segura
- Pediatric Neurology Department, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | | | | | - Rafael Camino León
- Pediatric Neurology Department, Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Víctor Soto Insuga
- Pediatric Neurology Department, Hospital Universitario Infantil del Niño Jesús, Madrid, Spain
| | - Elena González Alguacil
- Pediatric Neurology Department, Hospital Universitario Infantil del Niño Jesús, Madrid, Spain
| | - Carlos Valera Dávila
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | - Alberto Fernández-Jaén
- Pediatric Neurology Department, Neurogenetics Section, Hospital Universitario Quironsalud, Madrid, Spain
| | - Laura Plans
- Mental Health in Intellectual Disability Specialized Service Althaia, Xarxa Assistencial, Manresa, Spain
| | - Ana Camacho
- Pediatric Neurology Department, Hospital 12 de Octubre, Universidad Complutense de Madrid, Madrid, Spain
| | - Nuria Visa-Reñé
- Paediatric Department, Arnau de Vilanova University Hospital, Lleida, Spain
| | | | | | - Itxaso Marti-Carrera
- Pediatric Neurology Department, Hospital Universitario Donostia, San Sebastian, Spain
| | | | - Meritxell Tomas Davi
- Mental Health in Intellectual Disability Specialized Service Althaia, Xarxa Assistencial, Manresa, Spain
| | - Merce Casadesus Sanchez
- Mental Health in Intellectual Disability Specialized Service Althaia, Xarxa Assistencial, Manresa, Spain
| | | | - Patricia Fuentes Pita
- Pediatric Neurology Department, Hospital Clínico Universitario Santiago de Compostela, Santiago de Compostela, Spain
| | | | - Mar O'Callaghan
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | | | - María Rosario Cazorla
- Pediatric Neurology Department, Puerta de Hierro Majadahonda Universitary Hospital, Madrid, Spain
| | | | | | - Júlia Sala-Coromina
- Pediatric Neurology Department, Vall d'Hebron University Hospital, Universitat Autónoma de Barcelona, Bercelona, Spain
| | - Alfons Macaya
- Pediatric Neurology Department, Vall d'Hebron University Hospital, Universitat Autónoma de Barcelona, Bercelona, Spain
| | - Amaia Lasa-Aranzasti
- Department of Clinical and Molecular Genetic Vall d'Hebron University Hospital, Universitat Autónoma de Barcelona, Bercelona, Spain
| | - Anna Ma Cueto-González
- Department of Clinical and Molecular Genetic Vall d'Hebron University Hospital, Universitat Autónoma de Barcelona, Bercelona, Spain
| | | | - Jaume Campistol Plana
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | - Mercedes Serrano
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | - Xenia Alonso
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | - Diego Del Castillo-Berges
- Molecular Physiology of the Synapse Laboratory, Institut de Recerca Sant Pau (IR Sant Pau), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marc Schwartz-Palleja
- Eurecat, Technology Center of Catalonia, Multimedia Technologies, Barcelona, Spain
- Center for Brain and Cognition (CBC), Department of Information Technologies and Communications (DTIC), Pompeu Fabra University, Barcelona, Catalonia, Spain
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Sofía Illescas
- Pediatric Neurometabolism: Neural Communication Mechanisms and Personalized Therapies Pediatric Neurology Department: Neural Communication Mechanisms and Personalized Therapies Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Alia Ramírez Camacho
- Department of Child Neurology, Epilepsy and Neurophysiology Unit, Member of the ERN EpiCARE, Hospital Sant Joan de Dèu, Barcelona, Spain
| | - Oscar Sans Capdevila
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | - Angeles García-Cazorla
- Pediatric Neurology Department Sant Joan de Déu (SJD) Children’s Hospital, Barcelona, Spain
| | - Àlex Bayés
- Molecular Physiology of the Synapse Laboratory, Institut de Recerca Sant Pau (IR Sant Pau), Universitat Autònoma de Barcelona, Barcelona, Spain
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Araki Y, Rajkovich KE, Gerber EE, Gamache TR, Johnson RC, Tran THN, Liu B, Zhu Q, Hong I, Kirkwood A, Huganir R. SynGAP regulates synaptic plasticity and cognition independently of its catalytic activity. Science 2024; 383:eadk1291. [PMID: 38422154 PMCID: PMC11188940 DOI: 10.1126/science.adk1291] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 12/28/2023] [Indexed: 03/02/2024]
Abstract
SynGAP is an abundant synaptic GTPase-activating protein (GAP) critical for synaptic plasticity, learning, memory, and cognition. Mutations in SYNGAP1 in humans result in intellectual disability, autistic-like behaviors, and epilepsy. Heterozygous Syngap1-knockout mice display deficits in synaptic plasticity, learning, and memory and exhibit seizures. It is unclear whether SynGAP imparts structural properties at synapses independently of its GAP activity. Here, we report that inactivating mutations within the GAP domain do not inhibit synaptic plasticity or cause behavioral deficits. Instead, SynGAP modulates synaptic strength by physically competing with the AMPA-receptor-TARP excitatory receptor complex in the formation of molecular condensates with synaptic scaffolding proteins. These results have major implications for developing therapeutic treatments for SYNGAP1-related neurodevelopmental disorders.
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Affiliation(s)
| | | | | | | | - Richard C. Johnson
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thanh Hai N. Tran
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Bian Liu
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Qianwen Zhu
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ingie Hong
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Alfredo Kirkwood
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Richard Huganir
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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6
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Choquet D. Shifting rules in a brain disorder. Science 2024; 383:950-951. [PMID: 38422158 DOI: 10.1126/science.adn8707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
The mode of action of a synaptic protein is challenged.
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Affiliation(s)
- Daniel Choquet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS, UMR 5297, F-33000 Bordeaux, France
- Bordeaux Imaging Center, University of Bordeaux, CNRS, INSERM, US4, UAR 3420, F-33000 Bordeaux, France
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7
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Cherra SJ, Lamb R. Interactions between Ras and Rap signaling pathways during neurodevelopment in health and disease. Front Mol Neurosci 2024; 17:1352731. [PMID: 38463630 PMCID: PMC10920261 DOI: 10.3389/fnmol.2024.1352731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/08/2024] [Indexed: 03/12/2024] Open
Abstract
The Ras family of small GTPases coordinates tissue development by modulating cell proliferation, cell-cell adhesion, and cellular morphology. Perturbations of any of these key steps alter nervous system development and are associated with neurological disorders. While the underlying causes are not known, genetic mutations in Ras and Rap GTPase signaling pathways have been identified in numerous neurodevelopmental disorders, including autism spectrum, neurofibromatosis, intellectual disability, epilepsy, and schizophrenia. Despite diverse clinical presentations, intersections between these two signaling pathways may provide a better understanding of how deviations in neurodevelopment give rise to neurological disorders. In this review, we focus on presynaptic and postsynaptic functions of Ras and Rap GTPases. We highlight various roles of these small GTPases during synapse formation and plasticity. Based on genomic analyses, we discuss how disease-related mutations in Ras and Rap signaling proteins may underlie human disorders. Finally, we discuss how recent observations have identified molecular interactions between these pathways and how these findings may provide insights into the mechanisms that underlie neurodevelopmental disorders.
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Affiliation(s)
- Salvatore J. Cherra
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY, United States
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8
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Chandravanshi LP, Agrawal P, Darwish HW, Trigun SK. Impairments of Spatial Memory and N-methyl-d-aspartate Receptors and Their Postsynaptic Signaling Molecules in the Hippocampus of Developing Rats Induced by As, Pb, and Mn Mixture Exposure. Brain Sci 2023; 13:1715. [PMID: 38137163 PMCID: PMC10742016 DOI: 10.3390/brainsci13121715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/24/2023] [Accepted: 11/29/2023] [Indexed: 12/24/2023] Open
Abstract
Exposure to metal mixtures is recognized as a real-life scenario, needing novel studies that can assess their complex effects on brain development. There is still a significant public health concern associated with chronic low levels of metal exposure. In contrast to other metals, these three metals (As, Pb, and Mn) are commonly found in various environmental and industrial contexts. In addition to additive or synergistic interactions, concurrent exposure to this metal mixture may also have neurotoxic effects that differ from those caused by exposure to single components. The NMDA receptor and several important signaling proteins are involved in learning, memory, and synaptic plasticity in the hippocampus, including CaMKII, postsynaptic density protein-95 (PSD-95), synaptic Ras GTPase activating protein (SynGAP), a negative regulator of Ras-MAPK activity, and CREB. We hypothesized that alterations in the above molecular players may contribute to metal mixture developmental neurotoxicity. Thus, the aim of this study was to investigate the effect of these metals and their mixture at low doses (As 4 mg, Pb 4 mg, and Mn 10 mg/kg bw/p.o) on NMDA receptors and their postsynaptic signaling proteins during developing periods (GD6 to PD59) of the rat brain. Rats exposed to As, Pb, and Mn individually or at the same doses in a triple-metal mixture (MM) showed impairments in learning and memory functions in comparison to the control group rats. Declined protein expressions of NR2A, PSD-95, p- CaMKII, and pCREB were observed in the metal mix-exposed rats, while the expression of SynGAP was found to be enhanced in the hippocampus as compared to the controls on PD60. Thereby, our data suggest that alterations in the NMDA receptor complex and postsynaptic signaling proteins could explain the cognitive dysfunctions caused by metal-mixture-induced developmental neurotoxicity in rats. These outcomes indicate that incessant metal mixture exposure may have detrimental consequences on brain development.
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Affiliation(s)
- Lalit P. Chandravanshi
- Department of Forensic Science, Sharda University, Greater Noida 201308, India; (L.P.C.); (P.A.)
| | - Prashant Agrawal
- Department of Forensic Science, Sharda University, Greater Noida 201308, India; (L.P.C.); (P.A.)
| | - Hany W. Darwish
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Surendra Kumar Trigun
- Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
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9
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Birtele M, Del Dosso A, Xu T, Nguyen T, Wilkinson B, Hosseini N, Nguyen S, Urenda JP, Knight G, Rojas C, Flores I, Atamian A, Moore R, Sharma R, Pirrotte P, Ashton RS, Huang EJ, Rumbaugh G, Coba MP, Quadrato G. Non-synaptic function of the autism spectrum disorder-associated gene SYNGAP1 in cortical neurogenesis. Nat Neurosci 2023; 26:2090-2103. [PMID: 37946050 DOI: 10.1038/s41593-023-01477-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/29/2023] [Indexed: 11/12/2023]
Abstract
Genes involved in synaptic function are enriched among those with autism spectrum disorder (ASD)-associated rare genetic variants. Dysregulated cortical neurogenesis has been implicated as a convergent mechanism in ASD pathophysiology, yet it remains unknown how 'synaptic' ASD risk genes contribute to these phenotypes, which arise before synaptogenesis. Here, we show that the synaptic Ras GTPase-activating (RASGAP) protein 1 (SYNGAP1, a top ASD risk gene) is expressed within the apical domain of human radial glia cells (hRGCs). In a human cortical organoid model of SYNGAP1 haploinsufficiency, we find dysregulated cytoskeletal dynamics that impair the scaffolding and division plane of hRGCs, resulting in disrupted lamination and accelerated maturation of cortical projection neurons. Additionally, we confirmed an imbalance in the ratio of progenitors to neurons in a mouse model of Syngap1 haploinsufficiency. Thus, SYNGAP1-related brain disorders may arise through non-synaptic mechanisms, highlighting the need to study genes associated with neurodevelopmental disorders (NDDs) in diverse human cell types and developmental stages.
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Affiliation(s)
- Marcella Birtele
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Ashley Del Dosso
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Tiantian Xu
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Xiangya Hospital, Central South University, Changsha, China
| | - Tuan Nguyen
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Brent Wilkinson
- Department of Psychiatry and Behavioral Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Negar Hosseini
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Sarah Nguyen
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jean-Paul Urenda
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Gavin Knight
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
| | - Camilo Rojas
- Departments of Neuroscience and Molecular Medicine, University of Florida Scripps Biomedical Research Institute, Jupiter, FL, USA
- Skaggs Graduate School of Chemical and Biological Sciences, Scripps Research, Jupiter, FL, USA
| | - Ilse Flores
- Department of Psychiatry and Behavioral Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Alexander Atamian
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Roger Moore
- Integrated Mass Spectrometry Shared Resource, City of Hope Comprehensive Cancer Center, Duarte, CA, USA
| | - Ritin Sharma
- Integrated Mass Spectrometry Shared Resource, City of Hope Comprehensive Cancer Center, Duarte, CA, USA
- Cancer and Cell Biology Division, Translational Genomics Research Institute, Phoenix, AZ, USA
| | - Patrick Pirrotte
- Integrated Mass Spectrometry Shared Resource, City of Hope Comprehensive Cancer Center, Duarte, CA, USA
- Cancer and Cell Biology Division, Translational Genomics Research Institute, Phoenix, AZ, USA
| | - Randolph S Ashton
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, USA
| | - Eric J Huang
- Department of Pathology, University of California, San Francisco, CA, USA
- Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine, University of California, San Francisco, CA, USA
| | - Gavin Rumbaugh
- Departments of Neuroscience and Molecular Medicine, University of Florida Scripps Biomedical Research Institute, Jupiter, FL, USA
- Skaggs Graduate School of Chemical and Biological Sciences, Scripps Research, Jupiter, FL, USA
| | - Marcelo P Coba
- Department of Psychiatry and Behavioral Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Giorgia Quadrato
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
- Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
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10
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Ma H, Khaled HG, Wang X, Mandelberg NJ, Cohen SM, He X, Tsien RW. Excitation-transcription coupling, neuronal gene expression and synaptic plasticity. Nat Rev Neurosci 2023; 24:672-692. [PMID: 37773070 DOI: 10.1038/s41583-023-00742-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2023] [Indexed: 09/30/2023]
Abstract
Excitation-transcription coupling (E-TC) links synaptic and cellular activity to nuclear gene transcription. It is generally accepted that E-TC makes a crucial contribution to learning and memory through its role in underpinning long-lasting synaptic enhancement in late-phase long-term potentiation and has more recently been linked to late-phase long-term depression: both processes require de novo gene transcription, mRNA translation and protein synthesis. E-TC begins with the activation of glutamate-gated N-methyl-D-aspartate-type receptors and voltage-gated L-type Ca2+ channels at the membrane and culminates in the activation of transcription factors in the nucleus. These receptors and ion channels mediate E-TC through mechanisms that include long-range signalling from the synapse to the nucleus and local interactions within dendritic spines, among other possibilities. Growing experimental evidence links these E-TC mechanisms to late-phase long-term potentiation and learning and memory. These advances in our understanding of the molecular mechanisms of E-TC mean that future efforts can focus on understanding its mesoscale functions and how it regulates neuronal network activity and behaviour in physiological and pathological conditions.
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Affiliation(s)
- Huan Ma
- Department of Neurobiology, Affiliated Mental Health Center and Hangzhou Seventh People's Hospital, Zhejiang University School of Medicine, Hangzhou, China.
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, Zhejiang University, Hangzhou, China.
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, China.
- Research Units for Emotion and Emotional Disorders, Chinese Academy of Medical Sciences, Beijing, China.
| | - Houda G Khaled
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, USA
- Center for Neural Science, New York University, New York, NY, USA
| | - Xiaohan Wang
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, USA
| | - Nataniel J Mandelberg
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, USA
| | - Samuel M Cohen
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, USA
| | - Xingzhi He
- Department of Neurobiology, Affiliated Mental Health Center and Hangzhou Seventh People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, Zhejiang University, Hangzhou, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, China
- Research Units for Emotion and Emotional Disorders, Chinese Academy of Medical Sciences, Beijing, China
| | - Richard W Tsien
- NYU Neuroscience Institute and Department of Neuroscience and Physiology, NYU Langone Medical Center, New York, NY, USA.
- Center for Neural Science, New York University, New York, NY, USA.
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11
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Sumathipala SH, Khan S, Kozol RA, Araki Y, Syed S, Huganir RL, Dallman JE. Context-dependent hyperactivity in syngap1a and syngap1b zebrafish autism models. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.20.557316. [PMID: 37786701 PMCID: PMC10541574 DOI: 10.1101/2023.09.20.557316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Background and Aims SYNGAP1 disorder is a prevalent genetic form of Autism Spectrum Disorder and Intellectual Disability (ASD/ID) and is caused by de novo or inherited mutations in one copy of the SYNGAP1 gene. In addition to ASD/ID, SYNGAP1 disorder is associated with comorbid symptoms including treatment-resistant-epilepsy, sleep disturbances, and gastrointestinal distress. Mechanistic links between these diverse symptoms and SYNGAP1 variants remain obscure, therefore, our goal was to generate a zebrafish model in which this range of symptoms can be studied. Methods We used CRISPR/Cas9 to introduce frameshift mutations in the syngap1a and syngap1b zebrafish duplicates (syngap1ab) and validated these stable models for Syngap1 loss-of-function. Because SYNGAP1 is extensively spliced, we mapped splice variants to the two zebrafish syngap1a and b genes and identified mammalian-like isoforms. We then quantified locomotory behaviors in zebrafish syngap1ab larvae under three conditions that normally evoke different arousal states in wild type larvae: aversive, high-arousal acoustic, medium-arousal dark, and low-arousal light stimuli. Results We show that CRISPR/Cas9 indels in zebrafish syngap1a and syngap1b produced loss-of-function alleles at RNA and protein levels. Our analyses of zebrafish Syngap1 isoforms showed that, as in mammals, zebrafish Syngap1 N- and C-termini are extensively spliced. We identified a zebrafish syngap1 α1-like variant that maps exclusively to the syngap1b gene. Quantifying locomotor behaviors showed that syngap1ab larvae are hyperactive compared to wild type but to differing degrees depending on the stimulus. Hyperactivity was most pronounced in low arousal settings, with overall movement increasing with the number of mutant syngap1 alleles. Conclusions Our data support mutations in zebrafish syngap1ab as causal for hyperactivity associated with elevated arousal that is especially pronounced in low-arousal environments.
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Affiliation(s)
- Sureni H. Sumathipala
- Department of Biology, University of Miami, Coral Gables, FL USA
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Suha Khan
- Department of Biology, University of Miami, Coral Gables, FL USA
| | - Robert A. Kozol
- Department of Biology, University of Miami, Coral Gables, FL USA
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter FL, USA
| | - Yoichi Araki
- Department of Neuroscience and Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Sheyum Syed
- Department of Physics, University of Miami, Coral Gables, FL USA
| | - Richard L. Huganir
- Department of Neuroscience and Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Julia E. Dallman
- Department of Biology, University of Miami, Coral Gables, FL USA
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12
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Silverman JL, Fenton T, Haouchine O, Hallam E, Smith E, Jackson K, Rahbarian D, Canales C, Adhikari A, Nord A, Ben-Shalom R. Hyperexcitability and translational phenotypes in a preclinical model of SYNGAP1 mutations. RESEARCH SQUARE 2023:rs.3.rs-3246655. [PMID: 37790402 PMCID: PMC10543290 DOI: 10.21203/rs.3.rs-3246655/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
SYNGAP1 is a critical gene for neuronal development, synaptic structure, and function. Although rare, the disruption of SYNGAP1 directly causes a genetically identifiable neurodevelopmental disorder (NDD) called SYNGAP1 -related intellectual disability. Without functional SynGAP1 protein, patients present with intellectual disability, motor impairments, and epilepsy. Previous work using mouse models with a variety of germline and conditional mutations has helped delineate SynGAP1's critical roles in neuronal structure and function, as well as key biochemical signaling pathways essential to synapse integrity. Homozygous loss of SYNGAP1 is embryonically lethal. Heterozygous mutations of SynGAP1 result in a broad range of phenotypes including increased locomotor activity, impaired working spatial memory, impaired cued fear memory, and increased stereotypic behavior. Our in vivo functional data, using the original germline mutation mouse line from the Huganir laboratory, corroborated robust hyperactivity and learning and memory deficits. Here, we describe impairments in the translational biomarker domain of sleep, characterized using neurophysiological data collected with wireless telemetric electroencephalography (EEG). We discovered Syngap1+/- mice exhibited elevated spike trains in both number and duration, in addition to elevated power, most notably in the delta power band. Primary neurons from Syngap1+/- mice displayed increased network firing activity, greater spikes per burst, and shorter inter-burst intervals between peaks using high density micro-electrode arrays (HD-MEA). This work is translational, innovative, and highly significant as it outlines functional impairments in Syngap1 mutant mice. Simultaneously, the work utilized untethered, wireless neurophysiology that can discover potential biomarkers of Syngap1 RI-D, for clinical trials, as it has done with other NDDs. Our work is substantial forward progress toward translational work for SynGAP1R-ID as it bridges in-vitro electrophysiological neuronal activity and function with in vivo neurophysiological brain activity and function. These data elucidate multiple quantitative, translational biomarkers in vivo and in vitro for the development of treatments for SYNGAP1-related intellectual disability.
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Affiliation(s)
- Jill L Silverman
- MIND Institute and Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine
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13
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Zhao M, Kwon SE. Interneuron-Targeted Disruption of SYNGAP1 Alters Sensory Representations in the Neocortex and Impairs Sensory Learning. J Neurosci 2023; 43:6212-6226. [PMID: 37558489 PMCID: PMC10476640 DOI: 10.1523/jneurosci.1997-22.2023] [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: 10/25/2022] [Revised: 07/18/2023] [Accepted: 07/20/2023] [Indexed: 08/11/2023] Open
Abstract
SYNGAP1 haploinsufficiency in humans leads to severe neurodevelopmental disorders characterized by intellectual disability, autism, epilepsy, and sensory processing deficits. However, the circuit mechanisms underlying these disorders are not well understood. In mice, a decrease of SynGAP levels results in cognitive deficits by interfering with the development of excitatory glutamatergic connections. Recent evidence suggests that SynGAP also plays a crucial role in the development and function of GABAergic inhibitory interneurons. Nevertheless, it remains uncertain whether and to what extent the expression of SYNGAP1 in inhibitory interneurons contributes to cortical circuit function and related behaviors. The activity of cortical neurons has not been measured simultaneously with behavior. To address these gaps, we recorded from layer 2/3 neurons in the primary whisker somatosensory cortex (wS1) of mice while they learned to perform a whisker tactile detection task. Our results demonstrate that mice with interneuron-specific SYNGAP1 haploinsufficiency exhibit learning deficits characterized by heightened behavioral responses in the absence of relevant sensory input and premature responses to unrelated sensory stimuli not associated with reward acquisition. These behavioral deficits are accompanied by specific circuit abnormalities within wS1. Interneuron-specific SYNGAP1 haploinsufficiency increases detrimental neuronal correlations directly related to task performance and enhances responses to irrelevant sensory stimuli unrelated to the reward acquisition. In summary, our findings indicate that a reduction of SynGAP in inhibitory interneurons impairs sensory representation in the primary sensory cortex by disrupting neuronal correlations, which likely contributes to the observed cognitive deficits in mice with pan-neuronal SYNGAP1 haploinsufficiency.SIGNIFICANCE STATEMENT SYNGAP1 haploinsufficiency leads to severe neurodevelopmental disorders. The exact nature of neural circuit dysfunction caused by SYNGAP1 haploinsufficiency remains poorly understood. SynGAP plays a critical role in the function of GABAergic inhibitory interneurons as well as glutamatergic pyramidal neurons in the neocortex. Whether and how decreasing SYNGAP1 level in inhibitory interneurons disrupts a behaviorally relevant circuit remains unclear. We measure neural activity and behavior in mice learning a perceptual task. Mice with interneuron-targeted disruption of SYNGAP1 display increased detrimental neuronal correlations and elevated responses to irrelevant sensory inputs, which are related to impaired task performance. These results show that cortical interneuron dysfunction contributes to sensory deficits in SYNGAP1 haploinsufficiency with important implications for identifying therapeutic targets.
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Affiliation(s)
- Meiling Zhao
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Sung Eun Kwon
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
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14
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Fenton TA, Haouchine OY, Hallam EL, Smith EM, Jackson KC, Rahbarian D, Canales C, Adhikari A, Nord AS, Ben-Shalom R, Silverman JL. Hyperexcitability and translational phenotypes in a preclinical model of SYNGAP1 mutations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.24.550093. [PMID: 37546838 PMCID: PMC10402099 DOI: 10.1101/2023.07.24.550093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
SYNGAP1 is a critical gene for neuronal development, synaptic structure, and function. Although rare, the disruption of SYNGAP1 directly causes a genetically identifiable neurodevelopmental disorder (NDD) called SYNGAP1-related intellectual disability. Without functional SynGAP1 protein, patients present with intellectual disability, motor impairments, and epilepsy. Previous work using mouse models with a variety of germline and conditional mutations has helped delineate SynGAP1's critical roles in neuronal structure and function, as well as key biochemical signaling pathways essential to synapse integrity. Homozygous loss of SYNGAP1 is embryonically lethal. Heterozygous mutations of SynGAP1 result in a broad range of phenotypes including increased locomotor activity, impaired working spatial memory, impaired cued fear memory, and increased stereotypic behavior. Our in vivo functional data, using the original germline mutation mouse line from the Huganir laboratory, corroborated robust hyperactivity and learning and memory deficits. Here, we describe impairments in the translational biomarker domain of sleep, characterized using neurophysiological data collected with wireless telemetric electroencephalography (EEG). We discovered Syngap1 +/- mice exhibited elevated spike trains in both number and duration, in addition to elevated power, most notably in the delta power band. Primary neurons from Syngap1 +/- mice displayed increased network firing activity, greater spikes per burst, and shorter inter-burst intervals between peaks using high density micro-electrode arrays (HD-MEA). This work is translational, innovative, and highly significant as it outlines functional impairments in Syngap1 mutant mice. Simultaneously, the work utilized untethered, wireless neurophysiology that can discover potential biomarkers of Syngap1R-ID, for clinical trials, as it has done with other NDDs. Our work is substantial forward progress toward translational work for SynGAP1R-ID as it bridges in-vitro electrophysiological neuronal activity and function with in vivo neurophysiological brain activity and function. These data elucidate multiple quantitative, translational biomarkers in vivo and in vitro for the development of treatments for SYNGAP1-related intellectual disability.
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15
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Araki Y, Gerber EE, Rajkovich KE, Hong I, Johnson RC, Lee HK, Kirkwood A, Huganir RL. Mouse models of SYNGAP1 -related intellectual disability. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542312. [PMID: 37293116 PMCID: PMC10245951 DOI: 10.1101/2023.05.25.542312] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
SYNGAP1 is a Ras-GTPase activating protein highly enriched at excitatory synapses in the brain. De novo loss-of-function mutations in SYNGAP1 are a major cause of genetically defined neurodevelopmental disorders (NDD). These mutations are highly penetrant and cause SYNGAP1 -related intellectual disability (SRID), a NDD characterized by cognitive impairment, social deficits, early-onset seizures, and sleep disturbances (1-5). Studies in rodent neurons have shown that Syngap1 regulates developing excitatory synapse structure and function (6-11), and heterozygous Syngap1 knockout mice have deficits in synaptic plasticity, learning and memory, and have seizures (9, 12-14). However, how specific SYNGAP1 mutations found in humans lead to disease has not been investigated in vivo. To explore this, we utilized the CRISPR-Cas9 system to generate knock-in mouse models with two distinct known causal variants of SRID: one with a frameshift mutation leading to a premature stop codon, SYNGAP1; L813RfsX22, and a second with a single-nucleotide mutation in an intron that creates a cryptic splice acceptor site leading to premature stop codon, SYNGAP1; c.3583-9G>A . While reduction in Syngap1 mRNA varies from 30-50% depending on the specific mutation, both models show ∼50% reduction in Syngap1 protein, have deficits in synaptic plasticity, and recapitulate key features of SRID including hyperactivity and impaired working memory. These data suggest that half the amount of SYNGAP1 protein is key to the pathogenesis of SRID. These results provide a resource to study SRID and establish a framework for the development of therapeutic strategies for this disorder. Significance Statement SYNGAP1 is a protein enriched at excitatory synapses in the brain that is an important regulator of synapse structure and function. SYNGAP1 mutations cause SYNGAP1 -related intellectual disability (SRID), a neurodevelopmental disorder with cognitive impairment, social deficits, seizures, and sleep disturbances. To explore how SYNGAP1 mutations found in humans lead to disease, we generated the first knock-in mouse models with causal SRID variants: one with a frameshift mutation and a second with an intronic mutation that creates a cryptic splice acceptor site. Both models show decreased Syngap1 mRNA and Syngap1 protein and recapitulate key features of SRID including hyperactivity and impaired working memory. These results provide a resource to study SRID and establish a framework for the development of therapeutic strategies. Highlights Two mouse models with SYNGAP1 -related intellectual disability (SRID) mutations found in humans were generated: one with a frameshift mutation that results in a premature stop codon and the other with an intronic mutation resulting in a cryptic splice acceptor site and premature stop codon. Both SRID mouse models show 35∼50% reduction in mRNA and ∼50% reduction in Syngap1 protein.Both SRID mouse models display deficits in synaptic plasticity and behavioral phenotypes found in people. RNA-seq confirmed cryptic splice acceptor activity in one SRID mouse model and revealed broad transcriptional changes also identified in Syngap1 +/- mice. Novel SRID mouse models generated here provide a resource and establish a framework for development of future therapeutic intervention.
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Affiliation(s)
- Yoichi Araki
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Elizabeth E Gerber
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Kacey E Rajkovich
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Ingie Hong
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Richard C Johnson
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Hey-Kyoung Lee
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Alfredo Kirkwood
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
| | - Richard L Huganir
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine
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16
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Yang R, Feng X, Arias-Cavieres A, Mitchell RM, Polo A, Hu K, Zhong R, Qi C, Zhang RS, Westneat N, Portillo CA, Nobrega MA, Hansel C, Garcia Iii AJ, Zhang X. Upregulation of SYNGAP1 expression in mice and human neurons by redirecting alternative splicing. Neuron 2023; 111:1637-1650.e5. [PMID: 36917980 PMCID: PMC10198817 DOI: 10.1016/j.neuron.2023.02.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/20/2022] [Accepted: 02/13/2023] [Indexed: 03/14/2023]
Abstract
The Ras GTPase-activating protein SYNGAP1 plays a central role in synaptic plasticity, and de novo SYNGAP1 mutations are among the most frequent causes of autism and intellectual disability. How SYNGAP1 is regulated during development and how to treat SYNGAP1-associated haploinsufficiency remain challenging questions. Here, we characterize an alternative 3' splice site (A3SS) of SYNGAP1 that induces nonsense-mediated mRNA decay (A3SS-NMD) in mouse and human neural development. We demonstrate that PTBP1/2 directly bind to and promote SYNGAP1 A3SS inclusion. Genetic deletion of the Syngap1 A3SS in mice upregulates Syngap1 protein and alleviates the long-term potentiation and membrane excitability deficits caused by a Syngap1 knockout allele. We further report a splice-switching oligonucleotide (SSO) that converts SYNGAP1 unproductive isoform to the functional form in human iPSC-derived neurons. This study describes the regulation and function of SYNGAP1 A3SS-NMD, the genetic rescue of heterozygous Syngap1 knockout mice, and the development of an SSO to potentially alleviate SYNGAP1-associated haploinsufficiency.
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Affiliation(s)
- Runwei Yang
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Xinran Feng
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Alejandra Arias-Cavieres
- Section of Emergency Medicine, Department of Medicine, Institute for Integrative Physiology, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Robin M Mitchell
- Department of Neurobiology, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Ashleigh Polo
- Section of Emergency Medicine, Department of Medicine, Institute for Integrative Physiology, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Kaining Hu
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Rong Zhong
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Cai Qi
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Rachel S Zhang
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Nathaniel Westneat
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Cristabel A Portillo
- Department of Neurobiology, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA; Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA 92697, USA
| | - Marcelo A Nobrega
- Department of Human Genetics, the University of Chicago, Chicago, IL 60637, USA
| | - Christian Hansel
- Department of Neurobiology, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Alfredo J Garcia Iii
- Section of Emergency Medicine, Department of Medicine, Institute for Integrative Physiology, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Xiaochang Zhang
- Department of Human Genetics, Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA.
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17
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Li X, Du Y, Chen X, Liu C. Emerging roles of O-glycosylation in regulating protein aggregation, phase separation, and functions. Curr Opin Chem Biol 2023; 75:102314. [PMID: 37156204 DOI: 10.1016/j.cbpa.2023.102314] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/28/2023] [Accepted: 04/02/2023] [Indexed: 05/10/2023]
Abstract
Protein O-glycosylation is widely identified in various proteins involved in diverse biological processes. Recent studies have demonstrated that O-glycosylation plays crucial and multifaceted roles in modulating protein amyloid aggregation and liquid-liquid phase separation (LLPS) under physiological conditions. Dysregulation of these processes is closely associated with human diseases such as neurodegenerative diseases (NDs) and cancers. In this review, we first summarize the distinct roles of O-glycosylation in regulating pathological aggregation of different amyloid proteins related to NDs and elaborate the underlying mechanisms of how O-glycosylation modulates protein aggregation kinetics, induces new aggregated structures, and mediates the pathogenesis of amyloid aggregates under diseased conditions. Furthermore, we introduce recent discoveries on O-GlcNAc-mediated regulation of synaptic LLPS and phase separation potency of low-complexity domain-enriched proteins. Finally, we identify challenges in future research and highlight the potential for developing new therapeutic strategies of NDs by targeting protein O-glycosylation.
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Affiliation(s)
- Xiang Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
| | - Yifei Du
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China; Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Xing Chen
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China; Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China; Synthetic and Functional Biomolecules Center, Peking University, Beijing, China; Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University, Beijing, China.
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China.
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18
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Megagiannis P, Suresh R, Rouleau GA, Zhou Y. Reversibility and therapeutic development for neurodevelopmental disorders, insights from genetic animal models. Adv Drug Deliv Rev 2022; 191:114562. [PMID: 36183904 DOI: 10.1016/j.addr.2022.114562] [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: 04/25/2022] [Revised: 08/30/2022] [Accepted: 09/24/2022] [Indexed: 01/24/2023]
Abstract
Neurodevelopmental Disorders (NDDs) encompass a broad spectrum of conditions resulting from atypical brain development. Over the past decades, we have had the fortune to witness enormous progress in diagnosis, etiology discovery, modeling, and mechanistic understanding of NDDs from both fundamental and clinical research. Here, we review recent neurobiological advances from experimental models of NDDs. We introduce several examples and highlight breakthroughs in reversal studies of phenotypes using genetically engineered models of NDDs. The in-depth understanding of brain pathophysiology underlying NDDs and evaluations of reversibility in animal models paves the foundation for discovering novel treatment options. We discuss how the expanding property of cutting-edge technologies, such as gene editing and AAV-mediated gene delivery, are leveraged in animal models for the therapeutic development of NDDs. We envision opportunities and challenges toward faithful modeling and fruitful clinical translation.
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Affiliation(s)
- Platon Megagiannis
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital; Faculty of Medicine and Health Sciences, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Rahul Suresh
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital; Faculty of Medicine and Health Sciences, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Guy A Rouleau
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital; Faculty of Medicine and Health Sciences, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Yang Zhou
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital; Faculty of Medicine and Health Sciences, McGill University, Montreal, Quebec H3A 2B4, Canada.
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19
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Nugent FS, Kirkwood A, Lupica CR, Sjöström PJ. Editorial: The synaptic basis of neuropathology. Front Synaptic Neurosci 2022; 14:1043480. [PMID: 36311440 PMCID: PMC9608123 DOI: 10.3389/fnsyn.2022.1043480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 09/29/2022] [Indexed: 01/27/2023] Open
Affiliation(s)
- Fereshteh S. Nugent
- F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, MD, United States
| | - Alfredo Kirkwood
- Department of Neuroscience, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
| | - Carl R. Lupica
- National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD, United States,*Correspondence: Carl R. Lupica
| | - P. Jesper Sjöström
- Brain Repair and Integrative Neuroscience Program, Department of Medicine, Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, QC, Canada,P. Jesper Sjöström
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20
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Qi C, Luo LD, Feng I, Ma S. Molecular mechanisms of synaptogenesis. Front Synaptic Neurosci 2022; 14:939793. [PMID: 36176941 PMCID: PMC9513053 DOI: 10.3389/fnsyn.2022.939793] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/27/2022] [Indexed: 11/29/2022] Open
Abstract
Synapses are the basic units for information processing and storage in the nervous system. It is only when the synaptic connection is established, that it becomes meaningful to discuss the structure and function of a circuit. In humans, our unparalleled cognitive abilities are correlated with an increase in the number of synapses. Additionally, genes involved in synaptogenesis are also frequently associated with neurological or psychiatric disorders, suggesting a relationship between synaptogenesis and brain physiology and pathology. Thus, understanding the molecular mechanisms of synaptogenesis is the key to the mystery of circuit assembly and neural computation. Furthermore, it would provide therapeutic insights for the treatment of neurological and psychiatric disorders. Multiple molecular events must be precisely coordinated to generate a synapse. To understand the molecular mechanisms underlying synaptogenesis, we need to know the molecular components of synapses, how these molecular components are held together, and how the molecular networks are refined in response to neural activity to generate new synapses. Thanks to the intensive investigations in this field, our understanding of the process of synaptogenesis has progressed significantly. Here, we will review the molecular mechanisms of synaptogenesis by going over the studies on the identification of molecular components in synapses and their functions in synaptogenesis, how cell adhesion molecules connect these synaptic molecules together, and how neural activity mobilizes these molecules to generate new synapses. Finally, we will summarize the human-specific regulatory mechanisms in synaptogenesis and results from human genetics studies on synaptogenesis and brain disorders.
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Affiliation(s)
- Cai Qi
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, United States
- *Correspondence: Cai Qi,
| | - Li-Da Luo
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, United States
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, United States
| | - Irena Feng
- Boston University School of Medicine, Boston, MA, United States
| | - Shaojie Ma
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, United States
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21
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Purushotham SS, Reddy NMN, D'Souza MN, Choudhury NR, Ganguly A, Gopalakrishna N, Muddashetty R, Clement JP. A perspective on molecular signalling dysfunction, its clinical relevance and therapeutics in autism spectrum disorder. Exp Brain Res 2022; 240:2525-2567. [PMID: 36063192 DOI: 10.1007/s00221-022-06448-x] [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: 06/01/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022]
Abstract
Intellectual disability (ID) and autism spectrum disorder (ASD) are neurodevelopmental disorders that have become a primary clinical and social concern, with a prevalence of 2-3% in the population. Neuronal function and behaviour undergo significant malleability during the critical period of development that is found to be impaired in ID/ASD. Human genome sequencing studies have revealed many genetic variations associated with ASD/ID that are further verified by many approaches, including many mouse and other models. These models have facilitated the identification of fundamental mechanisms underlying the pathogenesis of ASD/ID, and several studies have proposed converging molecular pathways in ASD/ID. However, linking the mechanisms of the pathogenic genes and their molecular characteristics that lead to ID/ASD has progressed slowly, hampering the development of potential therapeutic strategies. This review discusses the possibility of recognising the common molecular causes for most ASD/ID based on studies from the available models that may enable a better therapeutic strategy to treat ID/ASD. We also reviewed the potential biomarkers to detect ASD/ID at early stages that may aid in diagnosis and initiating medical treatment, the concerns with drug failure in clinical trials, and developing therapeutic strategies that can be applied beyond a particular mutation associated with ASD/ID.
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Affiliation(s)
- Sushmitha S Purushotham
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Neeharika M N Reddy
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Michelle Ninochka D'Souza
- Centre for Brain Research, Indian Institute of Science Campus, CV Raman Avenue, Bangalore, 560 012, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India
| | - Nilpawan Roy Choudhury
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Anusa Ganguly
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Niharika Gopalakrishna
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Ravi Muddashetty
- Centre for Brain Research, Indian Institute of Science Campus, CV Raman Avenue, Bangalore, 560 012, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India
| | - James P Clement
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India.
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22
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Yasuda R, Hayashi Y, Hell JW. CaMKII: a central molecular organizer of synaptic plasticity, learning and memory. Nat Rev Neurosci 2022; 23:666-682. [PMID: 36056211 DOI: 10.1038/s41583-022-00624-2] [Citation(s) in RCA: 109] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2022] [Indexed: 12/30/2022]
Abstract
Calcium-calmodulin (CaM)-dependent protein kinase II (CaMKII) is the most abundant protein in excitatory synapses and is central to synaptic plasticity, learning and memory. It is activated by intracellular increases in calcium ion levels and triggers molecular processes necessary for synaptic plasticity. CaMKII phosphorylates numerous synaptic proteins, thereby regulating their structure and functions. This leads to molecular events crucial for synaptic plasticity, such as receptor trafficking, localization and activity; actin cytoskeletal dynamics; translation; and even transcription through synapse-nucleus shuttling. Several new tools affording increasingly greater spatiotemporal resolution have revealed the link between CaMKII activity and downstream signalling processes in dendritic spines during synaptic and behavioural plasticity. These technologies have provided insights into the function of CaMKII in learning and memory.
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Affiliation(s)
- Ryohei Yasuda
- Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA.
| | - Yasunori Hayashi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA, USA.
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23
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O-GlcNAcylation modulates liquid–liquid phase separation of SynGAP/PSD-95. Nat Chem 2022; 14:831-840. [DOI: 10.1038/s41557-022-00946-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 04/07/2022] [Indexed: 12/13/2022]
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24
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Rho-Rho-Kinase Regulates Ras-ERK Signaling Through SynGAP1 for Dendritic Spine Morphology. Neurochem Res 2022; 47:2757-2772. [PMID: 35624196 DOI: 10.1007/s11064-022-03623-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 10/18/2022]
Abstract
The structural plasticity of dendritic spines plays a critical role in NMDA-induced long-term potentiation (LTP) in the brain. The small GTPases RhoA and Ras are considered key regulators of spine morphology and enlargement. However, the regulatory interaction between RhoA and Ras underlying NMDA-induced spine enlargement is largely unknown. In this study, we found that Rho-kinase/ROCK, an effector of RhoA, phosphorylated SynGAP1 (a synaptic Ras-GTPase activating protein) at Ser842 and increased its interaction with 14-3-3ζ, thereby activating Ras-ERK signaling in a reconstitution system in HeLa cells. We also found that the stimulation of NMDA receptor by glycine treatment for LTP induction stimulated SynGAP1 phosphorylation, Ras-ERK activation, spine enlargement and SynGAP1 delocalization from the spines in striatal neurons, and these effects were prevented by Rho-kinase inhibition. Rho-kinase-mediated phosphorylation of SynGAP1 appeared to increase its dissociation from PSD95, a postsynaptic scaffolding protein located at postsynaptic density, by forming a complex with 14-3-3ζ. These results suggest that Rho-kinase phosphorylates SynGAP1 at Ser842, thereby activating the Ras-ERK pathway for NMDA-induced morphological changes in dendritic spines.
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25
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Kilinc M, Arora V, Creson TK, Rojas C, Le AA, Lauterborn J, Wilkinson B, Hartel N, Graham N, Reich A, Gou G, Araki Y, Bayés À, Coba M, Lynch G, Miller CA, Rumbaugh G. Endogenous Syngap1 alpha splice forms promote cognitive function and seizure protection. eLife 2022; 11:e75707. [PMID: 35394425 PMCID: PMC9064290 DOI: 10.7554/elife.75707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 04/08/2022] [Indexed: 11/13/2022] Open
Abstract
Loss-of-function variants in SYNGAP1 cause a developmental encephalopathy defined by cognitive impairment, autistic features, and epilepsy. SYNGAP1 splicing leads to expression of distinct functional protein isoforms. Splicing imparts multiple cellular functions of SynGAP proteins through coding of distinct C-terminal motifs. However, it remains unknown how these different splice sequences function in vivo to regulate neuronal function and behavior. Reduced expression of SynGAP-α1/2 C-terminal splice variants in mice caused severe phenotypes, including reduced survival, impaired learning, and reduced seizure latency. In contrast, upregulation of α1/2 expression improved learning and increased seizure latency. Mice expressing α1-specific mutations, which disrupted SynGAP cellular functions without altering protein expression, promoted seizure, disrupted synapse plasticity, and impaired learning. These findings demonstrate that endogenous SynGAP isoforms with α1/2 spliced sequences promote cognitive function and impart seizure protection. Regulation of SynGAP-αexpression or function may be a viable therapeutic strategy to broadly improve cognitive function and mitigate seizure.
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Affiliation(s)
- Murat Kilinc
- Graduate School of Chemical and Biological Sciences, The Scripps Research InstituteJupiterUnited States
- Departments of Neuroscience and Molecular Medicine, The Scripps Research InstituteJupiterUnited States
| | - Vineet Arora
- Departments of Neuroscience and Molecular Medicine, The Scripps Research InstituteJupiterUnited States
| | - Thomas K Creson
- Departments of Neuroscience and Molecular Medicine, The Scripps Research InstituteJupiterUnited States
| | - Camilo Rojas
- Departments of Neuroscience and Molecular Medicine, The Scripps Research InstituteJupiterUnited States
| | - Aliza A Le
- Department of Anatomy and Neurobiology, The University of CaliforniaIrvineUnited States
| | - Julie Lauterborn
- Department of Anatomy and Neurobiology, The University of CaliforniaIrvineUnited States
| | - Brent Wilkinson
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern CaliforniaLos AngelesUnited States
| | - Nicolas Hartel
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern CaliforniaLos AngelesUnited States
| | - Nicholas Graham
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern CaliforniaLos AngelesUnited States
| | - Adrian Reich
- Bioinformatics and Statistics Core, The Scripps Research InstituteJupiterUnited States
| | - Gemma Gou
- Molecular Physiology of the Synapse Laboratory, Institut d'Investigació Biomèdica Sant PauBarcelonaSpain
- Universitat Autònoma de BarcelonaBellaterraSpain
| | - Yoichi Araki
- Department of Neuroscience, Johns Hopkins School of MedicineBaltimoreUnited States
| | - Àlex Bayés
- Molecular Physiology of the Synapse Laboratory, Institut d'Investigació Biomèdica Sant PauBarcelonaSpain
| | - Marcelo Coba
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern CaliforniaLos AngelesUnited States
| | - Gary Lynch
- Department of Anatomy and Neurobiology, The University of CaliforniaIrvineUnited States
| | - Courtney A Miller
- Graduate School of Chemical and Biological Sciences, The Scripps Research InstituteJupiterUnited States
- Departments of Neuroscience and Molecular Medicine, The Scripps Research InstituteJupiterUnited States
| | - Gavin Rumbaugh
- Graduate School of Chemical and Biological Sciences, The Scripps Research InstituteJupiterUnited States
- Departments of Neuroscience and Molecular Medicine, The Scripps Research InstituteJupiterUnited States
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26
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Panagiotakos G, Pasca SP. A matter of space and time: Emerging roles of disease-associated proteins in neural development. Neuron 2022; 110:195-208. [PMID: 34847355 PMCID: PMC8776599 DOI: 10.1016/j.neuron.2021.10.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/11/2021] [Accepted: 10/25/2021] [Indexed: 01/21/2023]
Abstract
Recent genetic studies of neurodevelopmental disorders point to synaptic proteins and ion channels as key contributors to disease pathogenesis. Although many of these proteins, such as the L-type calcium channel Cav1.2 or the postsynaptic scaffolding protein SHANK3, have well-studied functions in mature neurons, new evidence indicates that they may subserve novel, distinct roles in immature cells as the nervous system is assembled in prenatal development. Emerging tools and technologies, including single-cell sequencing and human cellular models of disease, are illuminating differential isoform utilization, spatiotemporal expression, and subcellular localization of ion channels and synaptic proteins in the developing brain compared with the adult, providing new insights into the regulation of developmental processes. We propose that it is essential to consider the temporally distinct and cell-specific roles of these proteins during development and maturity in our framework for understanding neuropsychiatric disorders.
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Affiliation(s)
- Georgia Panagiotakos
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA.
| | - Sergiu P Pasca
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA; Stanford Brain Organogenesis, Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, USA.
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27
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Buller-Peralta I, Maicas-Royo J, Lu Z, Till SM, Wood ER, Kind PC, Escudero J, Gonzalez-Sulser A. Abnormal brain state distribution and network connectivity in a SYNGAP1 rat model. Brain Commun 2022; 4:fcac263. [PMID: 36349120 PMCID: PMC9638780 DOI: 10.1093/braincomms/fcac263] [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: 02/04/2022] [Revised: 07/09/2022] [Accepted: 10/13/2022] [Indexed: 11/09/2022] Open
Abstract
Mutations in the SYNGAP1 gene are one of the common predictors of neurodevelopmental disorders, commonly resulting in individuals developing autism, intellectual disability, epilepsy, and sleep deficits. EEG recordings in neurodevelopmental disorders show potential to identify clinically translatable biomarkers to both diagnose and track the progress of novel therapeutic strategies, as well as providing insight into underlying pathological mechanisms. In a rat model of SYNGAP1 haploinsufficiency in which the exons encoding the calcium/lipid binding and GTPase-activating protein domains have been deleted (Syngap+/Δ-GAP ), we analysed the duration and occurrence of wake, non-rapid eye movement and rapid eye movement brain states during 6 h multi-electrode EEG recordings. We find that although Syngap+/Δ-GAP animals spend an equivalent percent time in wake and sleep states, they have an abnormal brain state distribution as the number of wake and non-rapid eye movement bouts are reduced and there is an increase in the average duration of both wake and non-rapid eye movement epochs. We perform connectivity analysis by calculating the average imaginary coherence between electrode pairs at varying distance thresholds during these states. In group averages from pairs of electrodes at short distances from each other, a clear reduction in connectivity during non-rapid eye movement is present between 11.5 Hz and 29.5 Hz, a frequency range that overlaps with sleep spindles, oscillatory phenomena thought to be important for normal brain function and memory consolidation. Sleep abnormalities were mostly uncorrelated to the electrophysiological signature of absence seizures, spike and wave discharges, as was the imaginary coherence deficit. Sleep spindles occurrence, amplitude, power and spread across multiple electrodes were not reduced in Syngap+/Δ-GAP rats, with only a small decrease in duration detected. Nonetheless, by analysing the dynamic imaginary coherence during sleep spindles, we found a reduction in high-connectivity instances between short-distance electrode pairs. Finally comparing the dynamic imaginary coherence during sleep spindles between individual electrode pairs, we identified a group of channels over the right somatosensory, association and visual cortices that have a significant reduction in connectivity during sleep spindles in mutant animals. This matched a significant reduction in connectivity during spindles when averaged regional comparisons were made. These data suggest that Syngap+/Δ-GAP rats have altered brain state dynamics and EEG connectivity, which may have clinical relevance for SYNGAP1 haploinsufficiency in humans.
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Affiliation(s)
- Ingrid Buller-Peralta
- Simons Initiative for the Developing Brain, Patrick Wild Centre, Centre for Discovery Brain Sciences, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Jorge Maicas-Royo
- Simons Initiative for the Developing Brain, Patrick Wild Centre, Centre for Discovery Brain Sciences, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Zhuoen Lu
- School of Engineering, Institute for Digital Communications, University of Edinburgh, EH9 3JL Edinburgh, United Kingdom
| | - Sally M Till
- Simons Initiative for the Developing Brain, Patrick Wild Centre, Centre for Discovery Brain Sciences, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Emma R Wood
- Simons Initiative for the Developing Brain, Patrick Wild Centre, Centre for Discovery Brain Sciences, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Peter C Kind
- Simons Initiative for the Developing Brain, Patrick Wild Centre, Centre for Discovery Brain Sciences, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
| | - Javier Escudero
- School of Engineering, Institute for Digital Communications, University of Edinburgh, EH9 3JL Edinburgh, United Kingdom
| | - Alfredo Gonzalez-Sulser
- Simons Initiative for the Developing Brain, Patrick Wild Centre, Centre for Discovery Brain Sciences, University of Edinburgh, EH8 9XD Edinburgh, United Kingdom
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28
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Lu X, Zhou M, Liu N, Zhang C, Zhao Z, Cai D. Synaptic Protein Phosphorylation Networks Are Associated With Electroacupuncture-Induced Circadian Control in the Suprachiasmatic Nucleus. Front Genet 2021; 12:762557. [PMID: 34976011 PMCID: PMC8717940 DOI: 10.3389/fgene.2021.762557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 11/29/2021] [Indexed: 11/23/2022] Open
Abstract
Phosphorylation is one of the most important posttranslational modifications and regulates the physiological process. While recent studies highlight a major role of phosphorylation in the regulation of sleep–wake cycles to a lesser extent, the phosphoproteome in the suprachiasmatic nucleus (SCN) is not well-understood. Herein, we reported that the EA treatment elicits partial reparation of circadian rhythmicity when mice were exposure to constant darkness for long time. We investigated the effects of EA on circadian rhythms in constant darkness between EA stimulation and free-running control. Next, mass spectrometry–based phosphoproteome was utilized to explore the molecular characteristics of EA-induced phosphorylation modification in the SCN. A total of 6,192 distinct phosphosites on 2,488 proteins were quantified. Functional annotation analysis and protein–protein interaction networks demonstrated the most significant enriched phosphor-proteins and phosphosites involved in postsynapse and glutamatergic synapse. The current data indicated that most of the altered molecules are structural proteins. The target proteins, NMDAR and CAMK2, were selected for verification, consistent with the results of LC–MS/MS. These findings revealed a complete profile of phosphorylation modification in response to EA.
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Affiliation(s)
| | | | | | | | | | - Dingjun Cai
- *Correspondence: Zhengyu Zhao, ; Dingjun Cai,
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29
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Liu Y, Ouyang P, Zheng Y, Mi L, Zhao J, Ning Y, Guo W. A Selective Review of the Excitatory-Inhibitory Imbalance in Schizophrenia: Underlying Biology, Genetics, Microcircuits, and Symptoms. Front Cell Dev Biol 2021; 9:664535. [PMID: 34746116 PMCID: PMC8567014 DOI: 10.3389/fcell.2021.664535] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 09/27/2021] [Indexed: 12/29/2022] Open
Abstract
Schizophrenia is a chronic disorder characterized by specific positive and negative primary symptoms, social behavior disturbances and cognitive deficits (e.g., impairment in working memory and cognitive flexibility). Mounting evidence suggests that altered excitability and inhibition at the molecular, cellular, circuit and network level might be the basis for the pathophysiology of neurodevelopmental and neuropsychiatric disorders such as schizophrenia. In the past decades, human and animal studies have identified that glutamate and gamma-aminobutyric acid (GABA) neurotransmissions are critically involved in several cognitive progresses, including learning and memory. The purpose of this review is, by analyzing emerging findings relating to the balance of excitatory and inhibitory, ranging from animal models of schizophrenia to clinical studies in patients with early onset, first-episode or chronic schizophrenia, to discuss how the excitatory-inhibitory imbalance may relate to the pathophysiology of disease phenotypes such as cognitive deficits and negative symptoms, and highlight directions for appropriate therapeutic strategies.
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Affiliation(s)
- Yi Liu
- National Clinical Research Center on Mental Disorders and Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Department of Psychiatry, The Affiliated Brain Hospital, Guangzhou Medical University, Guangzhou, China
| | - Pan Ouyang
- National Clinical Research Center on Mental Disorders and Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yingjun Zheng
- Department of Psychiatry, The Affiliated Brain Hospital, Guangzhou Medical University, Guangzhou, China
| | - Lin Mi
- Department of Psychiatry, The Affiliated Brain Hospital, Guangzhou Medical University, Guangzhou, China
| | - Jingping Zhao
- National Clinical Research Center on Mental Disorders and Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yuping Ning
- Department of Psychiatry, The Affiliated Brain Hospital, Guangzhou Medical University, Guangzhou, China.,The First School of Clinical Medical University, Guangzhou, China
| | - Wenbin Guo
- National Clinical Research Center on Mental Disorders and Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China
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30
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Abstract
The presence of unprovoked, recurrent seizures, particularly when drug resistant and associated with cognitive and behavioral deficits, warrants investigation for an underlying genetic cause. This article provides an overview of the major classes of genes associated with epilepsy phenotypes divided into functional categories along with the recommended work-up and therapeutic considerations. Gene discovery in epilepsy supports counseling and anticipatory guidance but also opens the door for precision medicine guiding therapy with a focus on those with disease-modifying effects.
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Affiliation(s)
- Luis A Martinez
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Yi-Chen Lai
- Department of Pediatrics, Section of Pediatric Critical Care Medicine, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - J Lloyd Holder
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Anne E Anderson
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA.
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31
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Zieger HL, Choquet D. Nanoscale synapse organization and dysfunction in neurodevelopmental disorders. Neurobiol Dis 2021; 158:105453. [PMID: 34314857 DOI: 10.1016/j.nbd.2021.105453] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/18/2021] [Accepted: 07/21/2021] [Indexed: 12/20/2022] Open
Abstract
Neurodevelopmental disorders such as those linked to intellectual disabilities or autism spectrum disorder are thought to originate in part from genetic defects in synaptic proteins. Single gene mutations linked to synapse dysfunction can broadly be separated in three categories: disorders of transcriptional regulation, disorders of synaptic signaling and disorders of synaptic scaffolding and structures. The recent developments in super-resolution imaging technologies and their application to synapses have unraveled a complex nanoscale organization of synaptic components. On the one hand, part of receptors, adhesion proteins, ion channels, scaffold elements and the pre-synaptic release machinery are partitioned in subsynaptic nanodomains, and the respective organization of these nanodomains has tremendous impact on synaptic function. For example, pre-synaptic neurotransmitter release sites are partly aligned with nanometer precision to postsynaptic receptor clusters. On the other hand, a large fraction of synaptic components is extremely dynamic and constantly exchanges between synaptic domains and extrasynaptic or intracellular compartments. It is largely the combination of the exquisitely precise nanoscale synaptic organization of synaptic components and their high dynamic that allows the rapid and profound regulation of synaptic function during synaptic plasticity processes that underlie adaptability of brain function, learning and memory. It is very tempting to speculate that genetic defects that lead to neurodevelopmental disorders and target synaptic scaffolds and structures mediate their deleterious impact on brain function through perturbing synapse nanoscale dynamic organization. We discuss here how applying super-resolution imaging methods in models of neurodevelopmental disorders could help in addressing this question.
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Affiliation(s)
- Hanna L Zieger
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Daniel Choquet
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France; Univ. Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, F-33000 Bordeaux, France.
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32
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Regulation of the Small GTPase Ras and Its Relevance to Human Disease. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2262:19-43. [PMID: 33977469 DOI: 10.1007/978-1-0716-1190-6_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ras research has experienced a considerable boost in recent years, not least prompted by the Ras initiative launched by the NCI in 2013 ( https://www.cancer.gov/research/key-initiatives/ras ), accompanied and conditioned by a strongly reinvigorated determination within the Ras community to develop therapeutics attacking directly the Ras oncoproteins. As a member of the small G-protein superfamily, function and transforming activity of Ras all revolve about its GDP/GTP loading status. For one thing, the extent of GTP loading will determine the proportion of active Ras in the cell, with implications for intensity and quality of downstream signaling. But also the rate of nucleotide exchange, i.e., the Ras-GDP/GTP cycling rate, can have a major impact on Ras function, as illustrated perhaps most impressively by newly discovered fast-cycling oncogenic mutants of the Ras-related GTPase Rac1. Thus, while the last years have witnessed memorable new findings and technical developments in the Ras field, leading to an improved insight into many aspects of Ras biology, they have not jolted at the basics, but rather deepened our view of the fundamental regulatory principles of Ras activity control. In this brief review, we revisit the role and mechanisms of Ras nucleotide loading and its implications for cancer in the light of recent findings.
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Garozzo MT, Caruso D, La Mendola FMC, Di Nora A, Romano K, Leonardi R, Falsaperla R, Zanghì A, Praticò AD. SYNGAP1 and Its Related Epileptic Syndromes. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1727144] [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
AbstractSynaptic Ras GTPase-activating protein 1 (SYNGAP1) is abundantly expressed in the postsynaptic space in brain tissue and has a crucial role in the regulation of the excitatory/inhibitory balance and in brain development. It is estimated that SYNGAP1 loss of function variants have an incidence of 1 to 4/10,000 individuals, mostly occurring de novo, even if few cases of vertical transmission of mosaic mutations have been reported. Loss-of-function mutations within this gene have been related with an epileptic encephalopathy characterized by eyelid myoclonia with absences (EMA) and myoclonic-atonic seizures (MAE) with early onset, commonly resistant to antiepileptic drugs (AED). Epilepsy is often associated with other clinical features, including truncal and/or facial hypotonia and/or ataxia with a wide-based and unsteady gate. Other clinical signs are intellectual disability, developmental delay, and behavioral and speech impairment, in a context of a normal neuroimaging study. In selected cases, dysmorphic features, skeletal abnormalities, and eye involvement are also described. The diagnosis of the disorder is usually established by multigene panel and, in unsolved cases, by exome sequencing. Management of the affected individuals involves different specialists and is mainly symptomatic. No clinical trials about the efficacy of AED in SYNGAP1 encephalopathy have been performed yet and Lamotrigine and valproate are commonly prescribed. In more than half of cases, however, epilepsy is refractory to AED.
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Affiliation(s)
- Maria Teresa Garozzo
- Unit of Pediatric and Pediatric Emergency, Hospital “Cannizzaro,” Catania, Italy
| | - Daniela Caruso
- Pediatrics Postgraduate Residency Program, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy
| | | | - Alessandra Di Nora
- Pediatrics Postgraduate Residency Program, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy
| | | | - Roberta Leonardi
- Unit of Rare Diseases of the Nervous System in Childhood, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, 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
- Unit of Rare Diseases of the Nervous System in Childhood, Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University of Catania, Catania, Italy
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Sahasrabudhe A, Begum F, Guevara CA, Morrison C, Hsiao K, Kezunovic N, Bozdagi-Gunal O, Benson DL. Cyfip1 Regulates SynGAP1 at Hippocampal Synapses. Front Synaptic Neurosci 2021; 12:581714. [PMID: 33613257 PMCID: PMC7892963 DOI: 10.3389/fnsyn.2020.581714] [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: 07/09/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
In humans, copy number variations in CYFIP1 appear to have sweeping physiological and structural consequences in the brain, either producing or altering the severity of intellectual disability, autism, and schizophrenia. Independently, SynGAP1 haploinsufficiency produces intellectual disability and, frequently, autism. Cyfip1 inhibits protein translation and promotes actin polymerization, and SynGAP1 is a synaptically localized Ras/Rap GAP. While these proteins are clearly distinct, studies investigating their functions in mice have shown that each regulates the maturation of synapses in the hippocampus and haploinsufficiency for either produces an exaggerated form of mGluR-dependent long-term depression, suggesting that some signaling pathways converge. In this study, we examined how Cyfip1 haploinsufficiency impacts SynGAP1 levels and localization, as well as potential sites for mechanistic interaction in mouse hippocampus. The data show that synaptic, but not total, levels of SynGAP1 in Cyfip1 +/- mice were abnormally low during early postnatal development and in adults. This may be in response to a shift in the balance of kinases that activate SynGAP1 as levels of Cdk5 were reduced and those of activated CaMKII were maintained in Cyfip1 +/- mice compared to wild-type mice. Alternatively, this could reflect altered actin dynamics as Rac1 activity in Cyfip1 +/- hippocampus was boosted significantly compared to wild-type mice, and levels of synaptic F-actin were generally enhanced due in part to an increase in the activity of the WAVE regulatory complex. Decreased synaptic SynGAP1 coupled with a CaMKII-mediated bias toward Rap1 inactivation at synapses is also consistent with increased levels of synaptic GluA2, increased AMPA receptor-mediated responses to stimulation, and increased levels of synaptic mGluR1/5 compared to wild-type mice. Collectively, our data suggest that Cyfip1 regulates SynGAP1 and the two proteins work coordinately at synapses to appropriately direct actin polymerization and GAP activity.
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Affiliation(s)
- Abhishek Sahasrabudhe
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States
| | - Fatema Begum
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States
| | - Christopher A Guevara
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States.,Graduate School of Biomedical Sciences, New York, NY, United States
| | - Chenel Morrison
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States
| | - Kuangfu Hsiao
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States
| | - Nebojsa Kezunovic
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States
| | - Ozlem Bozdagi-Gunal
- Department of Psychiatry, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Deanna L Benson
- Icahn School of Medicine at Mount Sinai, Nash Family Department of Neuroscience, Friedman Brain Institute, New York, NY, United States
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Multi-parametric analysis of 57 SYNGAP1 variants reveal impacts on GTPase signaling, localization, and protein stability. Am J Hum Genet 2021; 108:148-162. [PMID: 33308442 DOI: 10.1016/j.ajhg.2020.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 11/16/2020] [Indexed: 11/20/2022] Open
Abstract
SYNGAP1 is a neuronal Ras and Rap GTPase-activating protein with important roles in regulating excitatory synaptic plasticity. While many SYNGAP1 missense and nonsense mutations have been associated with intellectual disability, epilepsy, schizophrenia, and autism spectrum disorder (ASD), whether and how they contribute to individual disease phenotypes is often unknown. Here, we characterize 57 variants in seven assays that examine multiple aspects of SYNGAP1 function. Specifically, we used multiplex phospho-flow cytometry to measure variant impact on protein stability, pERK, pGSK3β, pp38, pCREB, and high-content imaging to examine subcellular localization. We find variants ranging from complete loss-of-function (LoF) to wild-type (WT)-like in their regulation of pERK and pGSK3β, while all variants retain at least partial ability to dephosphorylate pCREB. Interestingly, our assays reveal that a larger proportion of variants located within the disordered domain of unknown function (DUF) comprising the C-terminal half of SYNGAP1 exhibited higher LoF, compared to variants within the better studied catalytic domain. Moreover, we find protein instability to be a major contributor to dysfunction for only two missense variants, both located within the catalytic domain. Using high-content imaging, we find variants located within the C2 domain known to mediate membrane lipid interactions exhibit significantly larger cytoplasmic speckles than WT SYNGAP1. Moreover, this subcellular phenotype shows both correlation with altered catalytic activity and unique deviation from signaling assay results, highlighting multiple independent molecular mechanisms underlying variant dysfunction. Our multidimensional dataset allows clustering of variants based on functional phenotypes and provides high-confidence, multi-functional measures for making pathogenicity predictions.
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Dysfunction of NMDA receptors in neuronal models of an autism spectrum disorder patient with a DSCAM mutation and in Dscam-knockout mice. Mol Psychiatry 2021; 26:7538-7549. [PMID: 34253863 PMCID: PMC8873012 DOI: 10.1038/s41380-021-01216-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 06/15/2021] [Accepted: 06/25/2021] [Indexed: 02/06/2023]
Abstract
Heterogeneity in the etiopathology of autism spectrum disorders (ASD) limits the development of generic remedies, requires individualistic and patient-specific research. Recent progress in human-induced pluripotent stem cell (iPSC) technology provides a novel platform for modeling ASDs for studying complex neuronal phenotypes. In this study, we generated telencephalic induced neuronal (iN) cells from iPSCs derived from an ASD patient with a heterozygous point mutation in the DSCAM gene. The mRNA of DSCAM and the density of DSCAM in dendrites were significantly decreased in ASD compared to control iN cells. RNA sequencing analysis revealed that several synaptic function-related genes including NMDA receptor subunits were downregulated in ASD iN cells. Moreover, NMDA receptor (R)-mediated currents were significantly reduced in ASD compared to control iN cells. Normal NMDA-R-mediated current levels were rescued by expressing wild-type DSCAM in ASD iN cells, and reduced currents were observed by truncated DSCAM expression in control iN cells. shRNA-mediated DSCAM knockdown in control iN cells resulted in the downregulation of an NMDA-R subunit, which was rescued by the overexpression of shRNA-resistant DSCAM. Furthermore, DSCAM was co-localized with NMDA-R components in the dendritic spines of iN cells whereas their co-localizations were significantly reduced in ASD iN cells. Levels of phospho-ERK1/2 were significantly lower in ASD iN cells, suggesting a potential mechanism. A neural stem cell-specific Dscam heterozygous knockout mouse model, showing deficits in social interaction and social memory with reduced NMDA-R currents. These data suggest that DSCAM mutation causes pathological symptoms of ASD by dysregulating NMDA-R function.
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Horner AE, Norris RH, McLaren-Jones R, Alexander L, Komiyama NH, Grant SGN, Nithianantharajah J, Kopanitsa MV. Learning and reaction times in mouse touchscreen tests are differentially impacted by mutations in genes encoding postsynaptic interacting proteins SYNGAP1, NLGN3, DLGAP1, DLGAP2 and SHANK2. GENES, BRAIN, AND BEHAVIOR 2021; 20:e12723. [PMID: 33347690 PMCID: PMC7615670 DOI: 10.1111/gbb.12723] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 12/15/2022]
Abstract
The postsynaptic terminal of vertebrate excitatory synapses contains a highly conserved multiprotein complex that comprises neurotransmitter receptors, cell-adhesion molecules, scaffold proteins and enzymes, which are essential for brain signalling and plasticity underlying behaviour. Increasingly, mutations in genes that encode postsynaptic proteins belonging to the PSD-95 protein complex, continue to be identified in neurodevelopmental disorders (NDDs) such as autism spectrum disorder, intellectual disability and epilepsy. These disorders are highly heterogeneous, sharing genetic aetiology and comorbid cognitive and behavioural symptoms. Here, by using genetically engineered mice and innovative touchscreen-based cognitive testing, we sought to investigate whether loss-of-function mutations in genes encoding key interactors of the PSD-95 protein complex display shared phenotypes in associative learning, updating of learned associations and reaction times. Our genetic dissection of mice with loss-of-function mutations in Syngap1, Nlgn3, Dlgap1, Dlgap2 and Shank2 showed that distinct components of the PSD-95 protein complex differentially regulate learning, cognitive flexibility and reaction times in cognitive processing. These data provide insights for understanding how human mutations in these genes lead to the manifestation of diverse and complex phenotypes in NDDs.
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Affiliation(s)
| | - Rebecca H Norris
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | | | | | - Noboru H Komiyama
- Genes to Cognition Programme, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
- Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Seth G N Grant
- Genes to Cognition Programme, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
- Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Jess Nithianantharajah
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Maksym V Kopanitsa
- Synome Ltd, Babraham Research Campus, Cambridge, UK
- UK Dementia Research Institute and Department of Brain Sciences, Imperial College, London, UK
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Aten S, Kalidindi A, Yoon H, Rumbaugh G, Hoyt KR, Obrietan K. SynGAP is expressed in the murine suprachiasmatic nucleus and regulates circadian-gated locomotor activity and light-entrainment capacity. Eur J Neurosci 2020; 53:732-749. [PMID: 33174316 DOI: 10.1111/ejn.15043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 12/15/2022]
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus functions as the master circadian clock. The phasing of the SCN oscillator is locked to the daily solar cycle, and an intracellular signaling cassette from the small GTPase Ras to the p44/42 mitogen-activated protein kinase (ERK/MAPK) pathway is central to this entrainment process. Here, we analyzed the expression and function of SynGAP-a GTPase-activating protein that serves as a negative regulator of Ras signaling-within the murine SCN. Using a combination of immunohistochemical and Western blotting approaches, we show that SynGAP is broadly expressed throughout the SCN. In addition, temporal profiling assays revealed that SynGAP expression is regulated over the circadian cycle, with peak expression occurring during the circadian night. Further, time-of-day-gated expression of SynGAP was not observed in clock arrhythmic BMAL1 null mice, indicating that the daily oscillation in SynGAP is driven by the inherent circadian timing mechanism. We also show that SynGAP phosphorylation at serine 1138-an event that has been found to modulate its functional efficacy-is regulated by clock time and is responsive to photic input. Finally, circadian phenotypic analysis of Syngap1 heterozygous mice revealed enhanced locomotor activity, increased sensitivity to light-evoked clock entrainment, and elevated levels of light-evoked MAPK activity, which is consistent with the role of SynGAP as a negative regulator of MAPK signaling. These findings reveal that SynGAP functions as a modulator of SCN clock entrainment, an effect that may contribute to sleep and circadian abnormalities observed in patients with SYNGAP1 gene mutations.
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Affiliation(s)
- Sydney Aten
- Department of Neuroscience, Ohio State University, Columbus, OH, USA
| | - Anisha Kalidindi
- Department of Neuroscience, Ohio State University, Columbus, OH, USA
| | - Hyojung Yoon
- Department of Neuroscience, Ohio State University, Columbus, OH, USA
| | - Gavin Rumbaugh
- Scripps Research, Department of Neuroscience, Jupiter, FL, USA.,Scripps Research, Department of Molecular Medicine, Jupiter, FL, USA
| | - Kari R Hoyt
- Division of Pharmaceutics and Pharmacology, Ohio State University, Columbus, OH, USA
| | - Karl Obrietan
- Department of Neuroscience, Ohio State University, Columbus, OH, USA
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Mizen LAM, Stanfield AC. Demystifying neuroscience laboratory techniques used to investigate single-gene disorders. BJPSYCH ADVANCES 2020. [DOI: 10.1192/bja.2020.30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
SUMMARYThere is considerable work being carried out in neuroscientific laboratories to delineate the mechanisms underlying single-gene disorders, particularly those related to intellectual disability and autism spectrum disorder. Many clinicians will have little if any direct experience of this type of work and so find the procedures and terminology difficult to understand. This article describes some of the laboratory techniques used and their increasing relevance to clinical practice. It is pitched for clinicians with little or no laboratory science background.
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Identification of an individual with a SYGNAP1 pathogenic mutation in India. Mol Biol Rep 2020; 47:9225-9234. [PMID: 33090308 DOI: 10.1007/s11033-020-05915-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/10/2020] [Indexed: 10/23/2022]
Abstract
Exome sequencing is a prominent tool to identify novel and deleterious mutations which could be non-sense, frameshift, and canonical splice-site mutations in a specific gene. De novo mutations in SYNGAP1, which codes for synaptic RAS-GTPase activating the protein, causes Intellectual disability (ID) and Autism Spectrum Disorder (ASD). SYNGAP1 related ASD/ID is one of the rare diseases that are detrimental to the healthy neuronal developmental and disrupts the global development of a child. We report the first SYNGAP1 heterozygous patient from Indian cohort. We report a case of a child of 2-year old with global developmental delay, microcephaly subtle dysmorphism, absence seizures, disrupted sleep, delay in learning a language, and eating problems. Upon further validation, the child has a few traits of ASD. Here, based on focused exome sequencing, we report a de novo heterozygous mutation in SYNGAP1 exon 11 with c. 1861 C > T (p.arg621ter). Currently, the child is on Atorvastatin, a RAS inhibitor, already available in the market for the treatment of hypercholesterolemia and has shown considerable improvement in global behaviour and cognitive development. The long-term follow up of the child's development would contribute to the already existing knowledge of the developmental trajectory in individuals with SYNGAP1 heterozygous mutation. In this report, we discuss the finding of a novel mutation in one of the genes, SYNGAP1, implicated in ASD/ID. Besides, we discuss the current treatment prescribed to the patient and the progress of global developmental of the child.
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Gou G, Roca-Fernandez A, Kilinc M, Serrano E, Reig-Viader R, Araki Y, Huganir RL, de Quintana-Schmidt C, Rumbaugh G, Bayés À. SynGAP splice variants display heterogeneous spatio-temporal expression and subcellular distribution in the developing mammalian brain. J Neurochem 2020; 154:618-634. [PMID: 32068252 PMCID: PMC7754318 DOI: 10.1111/jnc.14988] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 02/04/2020] [Accepted: 02/17/2020] [Indexed: 11/28/2022]
Abstract
The SynGAP protein is a major regulator of synapse biology and neural circuit function. Genetic variants linked to epilepsy and intellectual disability disrupt synaptic function and neural excitability. SynGAP has been involved in multiple signaling pathways and can regulate small GTPases with very different roles. Yet, the molecular bases behind this pleiotropy are poorly understood. We hypothesize that different SynGAP isoforms will mediate different sets of functions and that deciphering their spatio-temporal expression and subcellular localization will accelerate understanding their multiple functions. Using isoform-specific antibodies recognizing SynGAP in mouse and human samples we found distinctive developmental expression patterns for all SynGAP isoforms in five mouse brain areas. Particularly noticeable was the delayed expression of SynGAP-α1 isoforms, which directly bind to postsynaptic density-95, in cortex and hippocampus during the first 2 weeks of postnatal development. Suggesting that during this period other isoforms would have a more prominent role. Furthermore, we observed subcellular localization differences between isoforms, particularly throughout postnatal development. Consistent with previous reports, SynGAP was enriched in the postsynaptic density in the mature forebrain. However, SynGAP was predominantly found in non-synaptic locations in a period of early postnatal development highly sensitive to SynGAP levels. While, α1 isoforms were always found enriched in the postsynaptic density, α2 isoforms changed from a non-synaptic to a mostly postsynaptic density localization with age and β isoforms were always found enriched in non-synaptic locations. The differential expression and subcellular distribution of SynGAP isoforms may contribute to isoform-specific regulation of small GTPases, explaining SynGAP pleiotropy.
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Affiliation(s)
- Gemma Gou
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
| | | | - Murat Kilinc
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Elena Serrano
- Biobank, Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain
| | - Rita Reig-Viader
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
| | - Yoichi Araki
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Richard L Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA
| | | | - Gavin Rumbaugh
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
| | - Àlex Bayés
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau (IIB Sant Pau), Barcelona, Spain.,Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
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Cinar H, Oliva R, Lin Y, Chen X, Zhang M, Chan HS, Winter R. Pressure Sensitivity of SynGAP/PSD-95 Condensates as a Model for Postsynaptic Densities and Its Biophysical and Neurological Ramifications. Chemistry 2020; 26:11024-11031. [PMID: 31910298 PMCID: PMC7496680 DOI: 10.1002/chem.201905269] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Indexed: 12/11/2022]
Abstract
Biomolecular condensates consisting of proteins and nucleic acids can serve critical biological functions, so that some condensates are referred as membraneless organelles. They can also be disease-causing, if their assembly is misregulated. A major physicochemical basis of the formation of biomolecular condensates is liquid-liquid phase separation (LLPS). In general, LLPS depends on environmental variables, such as temperature and hydrostatic pressure. The effects of pressure on the LLPS of a binary SynGAP/PSD-95 protein system mimicking postsynaptic densities, which are protein assemblies underneath the plasma membrane of excitatory synapses, were investigated. Quite unexpectedly, the model system LLPS is much more sensitive to pressure than the folded states of typical globular proteins. Phase-separated droplets of SynGAP/PSD-95 were found to dissolve into a homogeneous solution already at ten-to-hundred bar levels. The pressure sensitivity of SynGAP/PSD-95 is seen here as a consequence of both pressure-dependent multivalent interaction strength and void volume effects. Considering that organisms in the deep sea are under pressures up to about 1 kbar, this implies that deep-sea organisms have to devise means to counteract this high pressure sensitivity of biomolecular condensates to avoid harm. Intriguingly, these findings may shed light on the biophysical underpinning of pressure-related neurological disorders in terrestrial vertebrates.
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Affiliation(s)
- Hasan Cinar
- Physical Chemistry I—Biophysical ChemistryFaculty of Chemistry and Chemical BiologyTU DortmundOtto-Hahn-Strasse 4a44227DortmundGermany
| | - Rosario Oliva
- Physical Chemistry I—Biophysical ChemistryFaculty of Chemistry and Chemical BiologyTU DortmundOtto-Hahn-Strasse 4a44227DortmundGermany
| | - Yi‐Hsuan Lin
- Department of BiochemistryFaculty of MedicineUniversity of TorontoTorontoOntarioM5S 1A8Canada
- Molecular MedicineHospital for Sick ChildrenTorontoOntarioM5G 0A4Canada
| | - Xudong Chen
- Division of Life ScienceState Key Laboratory of Molecular NeuroscienceHong Kong University of Science and TechnologyClear Water BayKowloon, Hong KongChina
| | - Mingjie Zhang
- Division of Life ScienceState Key Laboratory of Molecular NeuroscienceHong Kong University of Science and TechnologyClear Water BayKowloon, Hong KongChina
| | - Hue Sun Chan
- Department of BiochemistryFaculty of MedicineUniversity of TorontoTorontoOntarioM5S 1A8Canada
| | - Roland Winter
- Physical Chemistry I—Biophysical ChemistryFaculty of Chemistry and Chemical BiologyTU DortmundOtto-Hahn-Strasse 4a44227DortmundGermany
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Hooshmandi M, Wong C, Khoutorsky A. Dysregulation of translational control signaling in autism spectrum disorders. Cell Signal 2020; 75:109746. [PMID: 32858122 DOI: 10.1016/j.cellsig.2020.109746] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 11/27/2022]
Abstract
Deviations from the optimal level of mRNA translation are linked to disorders with high rates of autism. Loss of function mutations in genes encoding translational repressors such as PTEN, TSC1, TSC2, and FMRP are associated with autism spectrum disorders (ASDs) in humans and their deletion in animals recapitulates many ASD-like phenotypes. Importantly, the activity of key translational control signaling pathways such as PI3K-mTORC1 and ERK is frequently dysregulated in autistic patients and animal models and their normalization rescues many abnormal phenotypes, suggesting a causal relationship. Mutations in several genes encoding proteins not directly involved in translational control have also been shown to mediate ASD phenotypes via altered signaling upstream of translation. This raises the possibility that the dysregulation of translational control signaling is a converging mechanism not only in familiar but also in sporadic forms of autism. Here, we overview the current knowledge on translational signaling in ASD and highlight how correcting the activity of key pathways upstream of translation reverses distinct ASD-like phenotypes.
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Affiliation(s)
- Mehdi Hooshmandi
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada
| | - Calvin Wong
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada
| | - Arkady Khoutorsky
- Department of Anesthesia, Faculty of Dentistry, McGill University, Montreal, QC H3A 0G1, Canada.
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Twenty Years of SynGAP Research: From Synapses to Cognition. J Neurosci 2020; 40:1596-1605. [PMID: 32075947 DOI: 10.1523/jneurosci.0420-19.2020] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/03/2020] [Accepted: 01/07/2020] [Indexed: 12/11/2022] Open
Abstract
SynGAP is a potent regulator of biochemical signaling in neurons and plays critical roles in neuronal function. It was first identified in 1998, and has since been extensively characterized as a mediator of synaptic plasticity. Because of its involvement in synaptic plasticity, SynGAP has emerged as a critical protein for normal cognitive function. In recent years, mutations in the SYNGAP1 gene have been shown to cause intellectual disability in humans and have been linked to other neurodevelopmental disorders, such as autism spectrum disorders and schizophrenia. While the structure and biochemical function of SynGAP have been well characterized, a unified understanding of the various roles of SynGAP at the synapse and its contributions to neuronal function remains to be achieved. In this review, we summarize and discuss the current understanding of the multifactorial role of SynGAP in regulating neuronal function gathered over the last two decades.
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Wu X, Cai Q, Feng Z, Zhang M. Liquid-Liquid Phase Separation in Neuronal Development and Synaptic Signaling. Dev Cell 2020; 55:18-29. [PMID: 32726576 DOI: 10.1016/j.devcel.2020.06.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 01/09/2023]
Abstract
Formation of biomolecular condensates that are not enclosed by membranes via liquid-liquid phase separation (LLPS) is a general strategy that cells adopt to organize membraneless subcellular compartments for diverse functions. Neurons are highly polarized with elaborate branching and functional compartmentalization of their neurites, thus, raising additional demand for the proper subcellular localization of both membraneless and membrane-based organelles. Recent studies have provided evidence that several protein assemblies involved in the establishment of neuronal stem cell (NSC) polarity and in the asymmetric division of NSCs form distinct molecular condensates via LLPS. In synapses of adult neurons, molecular apparatuses controlling presynaptic neurotransmitter release and postsynaptic signaling transmission are also likely formed via LLPS. These molecular condensates, though not enclosed by lipid bilayers, directly associate with plasma membranes or membrane-based organelles, indicating that direct communication between membraneless and membrane-based organelles is a common theme in neurons and other types of cells.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Qixu Cai
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zhe Feng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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Liquid-liquid phase separation in biology: mechanisms, physiological functions and human diseases. SCIENCE CHINA. LIFE SCIENCES 2020; 63:953-985. [PMID: 32548680 DOI: 10.1007/s11427-020-1702-x] [Citation(s) in RCA: 151] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/20/2020] [Indexed: 02/06/2023]
Abstract
Cells are compartmentalized by numerous membrane-enclosed organelles and membraneless compartments to ensure that a wide variety of cellular activities occur in a spatially and temporally controlled manner. The molecular mechanisms underlying the dynamics of membrane-bound organelles, such as their fusion and fission, vesicle-mediated trafficking and membrane contactmediated inter-organelle interactions, have been extensively characterized. However, the molecular details of the assembly and functions of membraneless compartments remain elusive. Mounting evidence has emerged recently that a large number of membraneless compartments, collectively called biomacromolecular condensates, are assembled via liquid-liquid phase separation (LLPS). Phase-separated condensates participate in various biological activities, including higher-order chromatin organization, gene expression, triage of misfolded or unwanted proteins for autophagic degradation, assembly of signaling clusters and actin- and microtubule-based cytoskeletal networks, asymmetric segregations of cell fate determinants and formation of pre- and post-synaptic density signaling assemblies. Biomacromolecular condensates can transition into different material states such as gel-like structures and solid aggregates. The material properties of condensates are crucial for fulfilment of their distinct functions, such as biochemical reaction centers, signaling hubs and supporting architectures. Cells have evolved multiple mechanisms to ensure that biomacromolecular condensates are assembled and disassembled in a tightly controlled manner. Aberrant phase separation and transition are causatively associated with a variety of human diseases such as neurodegenerative diseases and cancers. This review summarizes recent major progress in elucidating the roles of LLPS in various biological pathways and diseases.
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Araki Y, Hong I, Gamache TR, Ju S, Collado-Torres L, Shin JH, Huganir RL. SynGAP isoforms differentially regulate synaptic plasticity and dendritic development. eLife 2020; 9:56273. [PMID: 32579114 PMCID: PMC7314543 DOI: 10.7554/elife.56273] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 06/07/2020] [Indexed: 11/14/2022] Open
Abstract
SynGAP is a synaptic Ras GTPase-activating protein (GAP) with four C-terminal splice variants: α1, α2, β, and γ. Although studies have implicated SYNGAP1 in several cognitive disorders, it is not clear which SynGAP isoforms contribute to disease. Here, we demonstrate that SynGAP isoforms exhibit unique spatiotemporal expression patterns and play distinct roles in neuronal and synaptic development in mouse neurons. SynGAP-α1, which undergoes liquid-liquid phase separation with PSD-95, is highly enriched in synapses and is required for LTP. In contrast, SynGAP-β, which does not bind PSD-95 PDZ domains, is less synaptically targeted and promotes dendritic arborization. A mutation in SynGAP-α1 that disrupts phase separation and synaptic targeting abolishes its ability to regulate plasticity and instead causes it to drive dendritic development like SynGAP-β. These results demonstrate that distinct intrinsic biochemical properties of SynGAP isoforms determine their function, and individual isoforms may differentially contribute to the pathogenesis of SYNGAP1-related cognitive disorders.
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Affiliation(s)
- Yoichi Araki
- Johns Hopkins University School of Medicine, Department of Neuroscience, Kavli Neuroscience Discovery Institute, Baltimore, United States
| | - Ingie Hong
- Johns Hopkins University School of Medicine, Department of Neuroscience, Kavli Neuroscience Discovery Institute, Baltimore, United States
| | - Timothy R Gamache
- Johns Hopkins University School of Medicine, Department of Neuroscience, Kavli Neuroscience Discovery Institute, Baltimore, United States
| | - Shaowen Ju
- Johns Hopkins University School of Medicine, Department of Neuroscience, Kavli Neuroscience Discovery Institute, Baltimore, United States
| | | | - Joo Heon Shin
- Lieber Institute for Brain Development, Baltimore, United States
| | - Richard L Huganir
- Johns Hopkins University School of Medicine, Department of Neuroscience, Kavli Neuroscience Discovery Institute, Baltimore, United States
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Sullivan BJ, Ammanuel S, Kipnis PA, Araki Y, Huganir RL, Kadam SD. Low-Dose Perampanel Rescues Cortical Gamma Dysregulation Associated With Parvalbumin Interneuron GluA2 Upregulation in Epileptic Syngap1 +/- Mice. Biol Psychiatry 2020; 87:829-842. [PMID: 32107006 PMCID: PMC7166168 DOI: 10.1016/j.biopsych.2019.12.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/19/2019] [Accepted: 12/19/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND Loss-of-function SYNGAP1 mutations cause a neurodevelopmental disorder characterized by intellectual disability and epilepsy. SYNGAP1 is a Ras GTPase-activating protein that underlies the formation and experience-dependent regulation of postsynaptic densities. The mechanisms that contribute to this proposed monogenic cause of intellectual disability and epilepsy remain unresolved. METHODS We established the phenotype of the epileptogenesis in a Syngap1+/- mouse model using 24-hour video electroencephalography (vEEG)/electromyography recordings at advancing ages. We administered an acute low dose of perampanel, a Food and Drug Administration-approved AMPA receptor (AMPAR) antagonist, during a follow-on 24-hour vEEG to investigate the role of AMPARs in Syngap1 haploinsufficiency. Immunohistochemistry was performed to determine the region- and location-specific differences in the expression of the GluA2 AMPAR subunit. RESULTS A progressive worsening of the epilepsy with emergence of multiple seizure phenotypes, interictal spike frequency, sleep dysfunction, and hyperactivity was identified in Syngap1+/- mice. Interictal spikes emerged predominantly during non-rapid eye movement sleep in 24-hour vEEG of Syngap1+/- mice. Myoclonic seizures occurred at behavioral-state transitions both in Syngap1+/- mice and during an overnight EEG from a child with SYNGAP1 haploinsufficiency. In Syngap1+/- mice, EEG spectral power analyses identified a significant loss of gamma power modulation during behavioral-state transitions. A significant region-specific increase of GluA2 AMPAR subunit expression in the somas of parvalbumin-positive interneurons was identified. CONCLUSIONS Acute dosing with perampanel significantly rescued behavioral state-dependent cortical gamma homeostasis, identifying a novel mechanism implicating Ca2+-impermeable AMPARs on parvalbumin-positive interneurons underlying circuit dysfunction in SYNGAP1 haploinsufficiency.
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Affiliation(s)
- Brennan J Sullivan
- Neuroscience Laboratory, Hugo Moser Research Institute, Kennedy Krieger Institute, Baltimore, Maryland
| | - Simon Ammanuel
- Department of Neurological Surgery, University of California San Francisco, San Francisco, California
| | - Pavel A Kipnis
- Neuroscience Laboratory, Hugo Moser Research Institute, Kennedy Krieger Institute, Baltimore, Maryland
| | - Yoichi Araki
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Richard L Huganir
- Department of Neuroscience, Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shilpa D Kadam
- Neuroscience Laboratory, Hugo Moser Research Institute, Kennedy Krieger Institute, Baltimore, Maryland; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
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Abstract
Emerging evidence indicates that liquid-liquid phase separation, the formation of a condensed molecular assembly within another diluted aqueous solution, is a means for cells to organize highly condensed biological assemblies (also known as biological condensates or membraneless compartments) with very broad functions and regulatory properties in different subcellular regions. Molecular machineries dictating synaptic transmissions in both presynaptic boutons and postsynaptic densities of neuronal synapses may be such biological condensates. Here we review recent developments showing how phase separation can build dense synaptic molecular clusters, highlight unique features of such condensed clusters in the context of synaptic development and signaling, discuss how aberrant phase-separation-mediated synaptic assembly formation may contribute to dysfunctional signaling in psychiatric disorders, and present some challenges and opportunities of phase separation in synaptic biology.
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Mastro TL, Preza A, Basu S, Chattarji S, Till SM, Kind PC, Kennedy MB. A sex difference in the response of the rodent postsynaptic density to synGAP haploinsufficiency. eLife 2020; 9:52656. [PMID: 31939740 PMCID: PMC6994236 DOI: 10.7554/elife.52656] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/14/2020] [Indexed: 11/17/2022] Open
Abstract
SynGAP is a postsynaptic density (PSD) protein that binds to PDZ domains of the scaffold protein PSD-95. We previously reported that heterozygous deletion of Syngap1 in mice is correlated with increased steady-state levels of other key PSD proteins that bind PSD-95, although the level of PSD-95 remains constant (Walkup et al., 2016). For example, the ratio to PSD-95 of Transmembrane AMPA-Receptor-associated Proteins (TARPs), which mediate binding of AMPA-type glutamate receptors to PSD-95, was increased in young Syngap1+/-mice. Here we show that only females and not males show a highly significant correlation between an increase in TARP and a decrease in synGAP in the PSDs of Syngap1+/-rodents. The data reveal a sex difference in the adaptation of the PSD scaffold to synGAP haploinsufficiency.
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Affiliation(s)
- Tara L Mastro
- Division of Biology and Biological Engineering, Caltech, Pasadena, United States
| | - Anthony Preza
- Division of Biology and Biological Engineering, Caltech, Pasadena, United States
| | - Shinjini Basu
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Sumantra Chattarji
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, Bangalore, India
| | - Sally M Till
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter C Kind
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, Bangalore, India
| | - Mary B Kennedy
- Division of Biology and Biological Engineering, Caltech, Pasadena, United States
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