1
|
De Fusco A, Cerullo MS, Marte A, Michetti C, Romei A, Castroflorio E, Baulac S, Benfenati F. Acute knockdown of Depdc5 leads to synaptic defects in mTOR-related epileptogenesis. Neurobiol Dis 2020; 139:104822. [PMID: 32113911 DOI: 10.1016/j.nbd.2020.104822] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/02/2020] [Accepted: 02/26/2020] [Indexed: 12/17/2022] Open
Abstract
DEP-domain containing 5 (DEPDC5) is part of the GATOR1 complex that functions as key inhibitor of the mechanistic target of rapamycin complex 1 (mTORC1). Loss-of-function mutations in DEPDC5 leading to mTOR hyperactivation have been identified as the most common cause of either lesional or non-lesional focal epilepsy. However, the precise mechanisms by which DEPDC5 loss-of-function triggers neuronal and network hyperexcitability are still unclear. In this study, we investigated the cellular mechanisms of hyperexcitability by comparing the constitutive heterozygous Depdc5 knockout mouse versus different levels of acute Depdc5 deletion (≈40% and ≈80% neuronal knockdown of Depdc5 protein) by RNA interference in primary cortical cultures. While heterozygous Depdc5+/- neurons have only a subtle phenotype, acutely knocked-down neurons exhibit a strong dose-dependent phenotype characterized by mTOR hyperactivation, increased soma size, dendritic arborization, excitatory synaptic transmission and intrinsic excitability. The robust synaptic phenotype resulting from the acute knockdown Depdc5 deficiency highlights the importance of the temporal dynamics of Depdc5 knockdown in triggering the phenotypic changes, reminiscent of the somatic second-hit mechanism in patients with focal cortical dysplasia. These findings uncover a novel synaptic phenotype that is causally linked to Depdc5 knockdown, highlighting the developmental role of Depdc5. Interestingly, the synaptic defect appears to affect only excitatory synapses, while inhibitory synapses develop normally. The increased frequency and amplitude of mEPSCs, paralleled by increased density of excitatory synapses and expression of glutamate receptors, may generate an excitation/inhibition imbalance that triggers epileptogenesis.
Collapse
Affiliation(s)
- Antonio De Fusco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Maria Sabina Cerullo
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Antonella Marte
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy; IRCSS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Caterina Michetti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; IRCSS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Alessandra Romei
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Enrico Castroflorio
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Stephanie Baulac
- Sorbonne Université, UPMC Univ Paris 06, UMR S 1127, INSERM, U1127, CNRS, UMR 7225, Institut du Cerveau et de la Moelle épinière (ICM), Hôpital Pitié-Salpêtrière, F-75013 Paris, France
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; IRCSS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy.
| |
Collapse
|
2
|
Garcia CAB, Carvalho SCS, Yang X, Ball LL, George RD, James KN, Stanley V, Breuss MW, Thomé U, Santos MV, Saggioro FP, Neder Serafini L, Silva WA, Gleeson JG, Machado HR. mTOR pathway somatic variants and the molecular pathogenesis of hemimegalencephaly. Epilepsia Open 2020; 5:97-106. [PMID: 32140648 PMCID: PMC7049797 DOI: 10.1002/epi4.12377] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 12/16/2019] [Accepted: 01/02/2020] [Indexed: 12/28/2022] Open
Abstract
Objectives Recently, defects in the protein kinase mTOR (mammalian target of rapamycin) and its associated pathway have been correlated with hemimegalencephaly (HME). mTOR acts as a central regulator of important physiological cellular functions such as growth and proliferation, metabolism, autophagy, death, and survival. This study was aimed at identifying specific variants in mTOR signaling pathway genes in patients diagnosed with HME. Methods Using amplicon and whole exome sequencing (WES) of resected brain and paired blood samples from five HME patients, we were able to identify pathogenic mosaic variants in the mTOR pathway genes MTOR, PIK3CA, and DEPDC5. Results These results strengthen the hypothesis that somatic variants in PI3K-Akt-mTOR pathway genes contribute to HME. We also describe one patient presenting with a pathogenic variant on DEPDC5 gene, which reinforces the role of DEPDC5 on cortical structural changes due to mTORC1 hyperactivation. These findings also provide insights into when in brain development these variants occurred. An early developmental variant is expected to affect a larger number of cells and to result in a larger malformation, whereas the same variant occurring later in development would cause a minor malformation. Significance In the future, numerous somatic variants in known or new genes will undoubtedly be revealed in resected brain samples, making it possible to draw correlations between genotypes and phenotypes and allow for a genetic clinical diagnosis that may help to predict a given patient's outcome.
Collapse
Affiliation(s)
- Camila A B Garcia
- Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Simone C S Carvalho
- Department of Genetics Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Xiaoxu Yang
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Laurel L Ball
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Renee D George
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Kiely N James
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Valentina Stanley
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Martin W Breuss
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Ursula Thomé
- Department of Neurosciences and Behavioral Sciences Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Marcelo V Santos
- Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Fabiano P Saggioro
- Department of Pathology Ribeirão Preto School of Medicine University of São Paulo USP Ribeirao Preto SP Brazil
| | - Luciano Neder Serafini
- Department of Pathology Ribeirão Preto School of Medicine University of São Paulo USP Ribeirao Preto SP Brazil
| | - Wilson A Silva
- Department of Genetics Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil.,Center for Medical Genomics University Hospital of Ribeirão Preto Medical School (USP) Ribeirao Preto SP Brazil
| | - Joseph G Gleeson
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Hélio R Machado
- Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| |
Collapse
|
3
|
Mutational inactivation of mTORC1 repressor gene DEPDC5 in human gastrointestinal stromal tumors. Proc Natl Acad Sci U S A 2019; 116:22746-22753. [PMID: 31636198 DOI: 10.1073/pnas.1914542116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Gastrointestinal stromal tumors (GISTs) are the most common human sarcoma and are initiated by activating mutations in the KIT or PDGFRA receptor tyrosine kinases. Chromosome 22q deletions are well-recognized frequent abnormalities in GISTs, occurring in ∼50% of GISTs. These deletions are thought to contribute to the pathogenesis of this disease via currently unidentified tumor suppressor mechanisms. Using whole exome sequencing, we report recurrent genomic inactivated DEPDC5 gene mutations in GISTs (16.4%, 9 of 55 patients). The demonstration of clonal DEPDC5 inactivation mutations in longitudinal specimens and in multiple metastases from individual patients suggests that these mutations have tumorigenic roles in GIST progression. DEPDC5 inactivation promotes GIST tumor growth in vitro and in nude mice. DEPDC5 reduces cell proliferation through the mTORC1-signaling pathway and subsequently induces cell-cycle arrest. Furthermore, DEPDC5 modulates the sensitivity of GIST to KIT inhibitors, and the combination therapy with mTOR inhibitor and KIT inhibitor may work better in GIST patients with DEPDC5 inactivation. These findings of recurrent genomic alterations, together with functional data, validate the DEPDC5 as a bona fide tumor suppressor contributing to GIST progression and a biologically relevant target of the frequent chromosome 22q deletions.
Collapse
|
4
|
Ye Z, McQuillan L, Poduri A, Green TE, Matsumoto N, Mefford HC, Scheffer IE, Berkovic SF, Hildebrand MS. Somatic mutation: The hidden genetics of brain malformations and focal epilepsies. Epilepsy Res 2019; 155:106161. [PMID: 31295639 DOI: 10.1016/j.eplepsyres.2019.106161] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/27/2019] [Accepted: 07/01/2019] [Indexed: 01/12/2023]
Abstract
Over the past decade there has been a substantial increase in genetic studies of brain malformations, fueled by the availability of improved technologies to study surgical tissue to address the hypothesis that focal lesions arise from focal, post-zygotic genetic disruptions. Traditional genetic studies of patients with malformations utilized leukocyte-derived DNA to search for germline variants, which are inherited or arise de novo in parental gametes. Recent studies have demonstrated somatic variants that arise post-zygotically also underlie brain malformations, and that somatic mutation explains a larger proportion of focal malformations than previously thought. We now know from studies of non-diseased individuals that somatic variation occurs routinely during cell division, including during early brain development when the rapid proliferation of neuronal precursor cells provides the ideal environment for somatic mutation to occur and somatic variants to accumulate. When confined to brain, pathogenic variants contribute to the "hidden genetics" of neurological diseases. With burgeoning novel high-throughput genetic technologies, somatic genetic variations are increasingly being recognized. Here we discuss accumulating evidence for the presence of somatic variants in normal brain tissue, review our current understanding of somatic variants in brain malformations associated with lesional epilepsy, and provide strategies to identify the potential contribution of somatic mutation to non-lesional epilepsies. We also discuss technologies that may improve detection of somatic variants in the future in these and other neurological conditions.
Collapse
Affiliation(s)
- Zimeng Ye
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Lara McQuillan
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, Boston, MA, United States
| | - Timothy E Green
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, WA, United States
| | - Ingrid E Scheffer
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia; Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Parkville, Victoria, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Samuel F Berkovic
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Michael S Hildebrand
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.
| |
Collapse
|
5
|
Iffland PH, Baybis M, Barnes AE, Leventer RJ, Lockhart PJ, Crino PB. DEPDC5 and NPRL3 modulate cell size, filopodial outgrowth, and localization of mTOR in neural progenitor cells and neurons. Neurobiol Dis 2018; 114:184-193. [PMID: 29481864 DOI: 10.1016/j.nbd.2018.02.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 01/30/2018] [Accepted: 02/21/2018] [Indexed: 11/27/2022] Open
Abstract
Mutations in DEPDC5 and NPRL3 subunits of GATOR1, a modulator of mechanistic target of rapamycin (mTOR), are linked to malformations of cortical development (MCD). Brain specimens from these individuals reveal abnormal cortical lamination, altered cell morphology, and hyperphosphorylation of ribosomal S6 protein (PS6), a marker for mTOR activation. While numerous studies have examined GATOR1 subunit function in non-neuronal cell lines, few have directly assessed loss of GATOR1 subunit function in neuronal cell types. We hypothesized that DEPDC5 or NPRL3 shRNA-mediated knockdown (DEPDC5/NPRL3 KD) leads to inappropriate functional activation of mTOR and mTOR-dependent alterations in neuronal morphology. Neuronal size was determined in human specimens harboring DEPDC5 or NPRL3 mutations resected for epilepsy treatment. DEPDC5/NPRL3 KD effects on cell size, filopodial extension, subcellular mTOR complex 1 (mTORC1) localization, and mTORC1 activation during nutrient deprivation were assayed in mouse neuroblastoma cells (N2aC) and mouse subventricular zone derived neural progenitor cells (mNPCs). mTORC1-dependent effects of DEPDC5/NPRL3 KD were determined using the mTOR inhibitor rapamycin. Changes in mTOR subcellular localization and mTORC1 pathway activation following DEPDC5/NPRL3 KD were determined by examining the proximity of mTOR to the lysosomal surface during amino acid starvation. Neurons exhibiting PS6 immunoreactivity (Ser 235/236) in human specimens were 1.5× larger than neurons in post-mortem control samples. DEPDC5/NPRL3 KD caused mTORC1, but not mTORC2, hyperactivation, soma enlargement, and increased filopodia in N2aC and mNPCs compared with wildtype cells. DEPDC5/NPRL3 KD led to inappropriate mTOR localization at the lysosome along with constitutive mTOR activation following amino acid deprivation. DEPDC5/NPRL3 KD effects on morphology and functional mTOR activation were reversed by rapamycin. mTOR-dependent effects of DEPDC5/NPRL3 KD on morphology and subcellular localization of mTOR in neurons suggests that loss-of-function in GATOR1 subunits may play a role in MCD formation during fetal brain development.
Collapse
Affiliation(s)
- Philip H Iffland
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States; Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Marianna Baybis
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States; Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Allan E Barnes
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Richard J Leventer
- Department of Neurology, Royal Children's Hospital and Neuroscience Research Group, Murdoch Children's Research Institute and University of Melbourne, Department of Pediatrics, Melbourne, Australia
| | - Paul J Lockhart
- Bruce Lefroy Center for Genetic Health Research, Murdoch Children's Research Institute, and University of Melbourne, Department of Pediatrics, Melbourne, Australia
| | - Peter B Crino
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States; Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States.
| |
Collapse
|
6
|
D'Gama AM, Woodworth MB, Hossain AA, Bizzotto S, Hatem NE, LaCoursiere CM, Najm I, Ying Z, Yang E, Barkovich AJ, Kwiatkowski DJ, Vinters HV, Madsen JR, Mathern GW, Blümcke I, Poduri A, Walsh CA. Somatic Mutations Activating the mTOR Pathway in Dorsal Telencephalic Progenitors Cause a Continuum of Cortical Dysplasias. Cell Rep 2017; 21:3754-3766. [PMID: 29281825 PMCID: PMC5752134 DOI: 10.1016/j.celrep.2017.11.106] [Citation(s) in RCA: 219] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 10/02/2017] [Accepted: 11/29/2017] [Indexed: 01/16/2023] Open
Abstract
Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are epileptogenic neurodevelopmental malformations caused by mutations in mTOR pathway genes. Deep sequencing of these genes in FCD/HME brain tissue identified an etiology in 27 of 66 cases (41%). Radiographically indistinguishable lesions are caused by somatic activating mutations in AKT3, MTOR, and PIK3CA and germline loss-of-function mutations in DEPDC5, NPRL2, and TSC1/2, including TSC2 mutations in isolated HME demonstrating a "two-hit" model. Mutations in the same gene cause a disease continuum from FCD to HME to bilateral brain overgrowth, reflecting the progenitor cell and developmental time when the mutation occurred. Single-cell sequencing demonstrated mTOR activation in neurons in all lesions. Conditional Pik3ca activation in the mouse cortex showed that mTOR activation in excitatory neurons and glia, but not interneurons, is sufficient for abnormal cortical overgrowth. These data suggest that mTOR activation in dorsal telencephalic progenitors, in some cases specifically the excitatory neuron lineage, causes cortical dysplasia.
Collapse
Affiliation(s)
- Alissa M D'Gama
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Mollie B Woodworth
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Amer A Hossain
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Sara Bizzotto
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Nicole E Hatem
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | | | - Imad Najm
- Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Zhong Ying
- Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Edward Yang
- Department of Radiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - A James Barkovich
- Departments of Radiology and Diagnostic Imaging, Neurology, Pediatrics, and Neurosurgery, University of California, San Francisco, San Francisco, CA 94143, USA
| | | | - Harry V Vinters
- Departments of Pathology and Laboratory Medicine (Neuropathology) and Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Joseph R Madsen
- Department of Neurosurgery, Boston Children's Hospital, Boston, MA, USA
| | - Gary W Mathern
- Departments of Neurosurgery and Psychiatry and Biobehavioral Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ingmar Blümcke
- Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA; Department of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Annapurna Poduri
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Epilepsy Genetics Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
| |
Collapse
|
7
|
Chen T, Giri M, Xia Z, Subedi YN, Li Y. Genetic and epigenetic mechanisms of epilepsy: a review. Neuropsychiatr Dis Treat 2017; 13:1841-1859. [PMID: 28761347 PMCID: PMC5516882 DOI: 10.2147/ndt.s142032] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Epilepsy is a common episodic neurological disorder or condition characterized by recurrent epileptic seizures, and genetics seems to play a key role in its etiology. Early linkage studies have localized multiple loci that may harbor susceptibility genes to epilepsy, and mutational analyses have detected a number of mutations involved in both ion channel and nonion channel genes in patients with idiopathic epilepsy. Genome-wide studies of epilepsy have found copy number variants at 2q24.2-q24.3, 7q11.22, 15q11.2-q13.3, and 16p13.11-p13.2, some of which disrupt multiple genes, such as NRXN1, AUTS2, NLGN1, CNTNAP2, GRIN2A, PRRT2, NIPA2, and BMP5, implicated for neurodevelopmental disorders, including intellectual disability and autism. Unfortunately, only a few common genetic variants have been associated with epilepsy. Recent exome-sequencing studies have found some genetic mutations, most of which are located in nonion channel genes such as the LGI1, PRRT2, EFHC1, PRICKLE, RBFOX1, and DEPDC5 and in probands with rare forms of familial epilepsy, and some of these genes are involved with the neurodevelopment. Since epigenetics plays a role in neuronal function from embryogenesis and early brain development to tissue-specific gene expression, epigenetic regulation may contribute to the genetic mechanism of neurodevelopment through which a gene and the environment interacting with each other affect the development of epilepsy. This review focused on the analytic tools used to identify epilepsy and then provided a summary of recent linkage and association findings, indicating the existence of novel genes on several chromosomes for further understanding of the biology of epilepsy.
Collapse
Affiliation(s)
- Tian Chen
- Department of Health Management Center, Chongqing Three Gorges Central Hospital, Chongqing, People's Republic of China
| | - Mohan Giri
- National Center for Rheumatic Diseases, Ratopul, Gaushala, Kathmandu, Nepal
| | - Zhenyi Xia
- Department of Thoracic Surgery, Chongqing Three Gorges Central Hospital, Chongqing, People's Republic of China
| | - Yadu Nanda Subedi
- National Center for Rheumatic Diseases, Ratopul, Gaushala, Kathmandu, Nepal
| | - Yan Li
- Department of Health Management Center, Chongqing Three Gorges Central Hospital, Chongqing, People's Republic of China
| |
Collapse
|
8
|
Sending Mixed Signals: The Expanding Role of Molecular Cascade Mutations in Malformations of Cortical Development and Epilepsy. Epilepsy Curr 2016; 16:158-63. [PMID: 27330441 DOI: 10.5698/1535-7511-16.3.158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Advances in gene sequencing techniques have led to a dramatic increase in the number of signaling cascade and cytoskeletal assembly mutations associated with malformations of cortical development and epilepsy. At the forefront of this research are novel mutations found in regulators of the PI3K/AKT/mTOR cascade and tubulin-associated malformations of cortical development. However, there is limited understanding of the consequences of these newly discovered germline and somatic mutations on cellular function or how these changes in cell biology may lead to areas-large or small-of malformed cortex and recurrent spontaneous seizures. We summarize and discuss what is currently known in this field in an effort to shine light on vast gaps in our knowledge of relatively common causes of cortical malformations.
Collapse
|
9
|
|
10
|
|
11
|
Jehi L, Wyllie E, Devinsky O. Epileptic encephalopathies: Optimizing seizure control and developmental outcome. Epilepsia 2015; 56:1486-9. [PMID: 26293588 DOI: 10.1111/epi.13107] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2015] [Indexed: 01/15/2023]
Abstract
Cognitive and developmental outcomes in patients with epileptic encephalopathy are hypothesized to result from an interplay between the underlying epileptic pathologic substrate and the acquired consequences of frequent and repetitive seizures and epileptiform discharges that often straddle the interictal and ictal boundaries. This article briefly reviews the evidence related to this assumption, presents critical questions that need to be answered to clarify this relationship, and advances a set of concrete steps that may help improve developmental patient outcomes.
Collapse
Affiliation(s)
- Lara Jehi
- Department of Neurology, Cleveland Clinic, Cleveland, Ohio, U.S.A
| | - Elaine Wyllie
- Department of Neurology, Cleveland Clinic, Cleveland, Ohio, U.S.A
| | - Orrin Devinsky
- NYU Comprehensive Epilepsy Center, New York, New York, U.S.A
| |
Collapse
|
12
|
Striano P, Serioli E, Santulli L, Manna I, Labate A, Dazzo E, Pasini E, Gambardella A, Michelucci R, Striano S, Nobile C. DEPDC5 mutations are not a frequent cause of familial temporal lobe epilepsy. Epilepsia 2015. [PMID: 26216793 DOI: 10.1111/epi.13094] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mutations in the DEPDC5 (DEP domain-containing protein 5) gene are a major cause of familial focal epilepsy with variable foci (FFEVF) and are predicted to account for 12-37% of families with inherited focal epilepsies. To assess the clinical impact of DEPDC5 mutations in familial temporal lobe epilepsy, we screened a collection of Italian families with either autosomal dominant lateral temporal epilepsy (ADLTE) or familial mesial temporal lobe epilepsy (FMTLE). The probands of 28 families classified as ADLTE and 17 families as FMTLE were screened for DEPDC5 mutations by whole exome or targeted massive parallel sequencing. Putative mutations were validated by Sanger sequencing. We identified a DEPDC5 nonsense mutation (c.918C>G; p.Tyr306*) in a family with two affected members, clinically classified as FMTLE. The proband had temporal lobe seizures with prominent psychic symptoms (déjà vu, derealization, and forced thoughts); her mother had temporal lobe seizures, mainly featuring visceral epigastric auras and anxiety. In total, we found a single DEPDC5 mutation in one of (2.2%) 45 families with genetic temporal lobe epilepsy, a proportion much lower than that reported in other inherited focal epilepsies.
Collapse
Affiliation(s)
- Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, G. Gaslini Institute, University of Genoa, Genova, Italy
| | - Elena Serioli
- CNR-Neuroscience Institute, Section of Padua, Padova, Italy
| | - Lia Santulli
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, School of Medicine, Federico II University, Napoli, Italy
| | - Ida Manna
- Institute of Molecular Bioimaging and Physiology, Section of Germaneto, National Research Council, Catanzaro, Italy
| | - Angelo Labate
- Institute of Molecular Bioimaging and Physiology, Section of Germaneto, National Research Council, Catanzaro, Italy.,Institute of Neurology, University Magna Graecia, Catanzaro, Italy
| | - Emanuela Dazzo
- CNR-Neuroscience Institute, Section of Padua, Padova, Italy
| | - Elena Pasini
- IRCCS-Institute of Neurological Sciences, Bellaria Hospital, Bologna, Italy
| | - Antonio Gambardella
- Institute of Molecular Bioimaging and Physiology, Section of Germaneto, National Research Council, Catanzaro, Italy.,Institute of Neurology, University Magna Graecia, Catanzaro, Italy
| | - Roberto Michelucci
- IRCCS-Institute of Neurological Sciences, Bellaria Hospital, Bologna, Italy
| | - Salvatore Striano
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, School of Medicine, Federico II University, Napoli, Italy
| | - Carlo Nobile
- CNR-Neuroscience Institute, Section of Padua, Padova, Italy.,Department of Biomedical Sciences, University of Padua, Padova, Italy
| |
Collapse
|
13
|
|
14
|
Abstract
As the genetic etiologies of an expanding number of epilepsy syndromes are revealed, the complexity of the phenotype genotype correlation increases. As our review will show, multiple gene mutations cause different epilepsy syndromes, making identification of the specific mutation increasingly more important for prognostication and often more directed treatment. Examples of that include the need to avoid specific drugs in Dravet syndrome and the ongoing investigations of the potential use of new directed therapies such as retigabine in KCNQ2-related epilepsies, quinidine in KCNT1-related epilepsies, and memantine in GRIN2A-related epilepsies.
Collapse
Affiliation(s)
- Abeer J Hani
- Division of Pediatric Neurology, Department of Pediatrics, Duke Children's Hospital and Health Center, Suite T0913J, 2301 Erwin Road, Durham, NC 27710, USA
| | - Husam M Mikati
- Center of Human Genome Variation, LSRC, Duke University School of Medicine, 201 Trent Drive, Durham, NC 27710, USA
| | - Mohamad A Mikati
- Division of Pediatric Neurology, Department of Pediatrics, Duke Children's Hospital and Health Center, Suite T0913J, 2301 Erwin Road, Durham, NC 27710, USA.
| |
Collapse
|
15
|
Baulac S, Ishida S, Marsan E, Miquel C, Biraben A, Nguyen DK, Nordli D, Cossette P, Nguyen S, Lambrecq V, Vlaicu M, Daniau M, Bielle F, Andermann E, Andermann F, Leguern E, Chassoux F, Picard F. Familial focal epilepsy with focal cortical dysplasia due toDEPDC5mutations. Ann Neurol 2015; 77:675-83. [DOI: 10.1002/ana.24368] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/07/2015] [Accepted: 01/14/2015] [Indexed: 01/14/2023]
Affiliation(s)
- Stéphanie Baulac
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
| | - Saeko Ishida
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
| | - Elise Marsan
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
| | - Catherine Miquel
- Sainte Anne Hospital Center, Paris Descartes University; Paris France
| | - Arnaud Biraben
- University of Rennes Hospital Center; Rennes France
- National Institute of Health and Medical Research; INSERM U1099, University of Rennes; Rennes France
| | - Dang Khoa Nguyen
- University of Montreal Hospital Center (Notre Dame Hospital); University of Montreal; Montreal Quebec Canada
| | - Doug Nordli
- Epilepsy Division, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University; Chicago IL
| | - Patrick Cossette
- University of Montreal Hospital Center (Notre Dame Hospital); University of Montreal; Montreal Quebec Canada
- Center of Excellence in Neuromics; University of Montreal; Montreal Quebec Canada
| | - Sylvie Nguyen
- Child Neurology Unit, Laboratoire Angevin de Recherche en Ingénierie des Systèmes (LARIS); Angers France
| | - Virginie Lambrecq
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
- Epilepsy Unit, Pitié-Salpêtrière Hospital, Public Hospital Network of Paris; Paris France
| | - Mihaela Vlaicu
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
- Neurosurgery Department; Pitié-Salpêtrière Hospital, Public Hospital Network of Paris; Paris France
| | - Maïlys Daniau
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
| | - Franck Bielle
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
- Neuropathology Department; Pitié-Salpêtrière Hospital, Public Hospital Network of Paris; Paris France
| | - Eva Andermann
- Neurogenetics Unit and Epilepsy Research Group; Montreal Neurological Hospital and Institute; Montreal Quebec Canada
- Departments of Neurology and Neurosurgery and Human Genetics; McGill University; Montreal Quebec Canada
| | - Frederick Andermann
- Seizure Clinic and Epilepsy Research Group; Montreal Neurological Hospital and Institute; Montreal Quebec Canada
- Department of Neurology and Neurosurgery and Department of Pediatrics; McGill University; Montreal Quebec Canada
| | - Eric Leguern
- Sorbonne Universités; Pierre and Marie Curie University; UPMC Univ Paris 06, UM 75, ICM; Paris France
- National Institute of Health and Medical Research, INSERM U1127, ICM; Paris France
- National Center for Scientific Research, CNRS, UMR 7225, ICM; Paris France
- Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM); Paris France
- Department of Genetics; Pitié-Salpêtrière Hospital, Public Hospital Network of Paris; Paris France
| | - Francine Chassoux
- Sainte Anne Hospital Center, Paris Descartes University; Paris France
- National Institute of Health and Medical Research; INSERM U1129, Paris Descartes University; Sorbonne Paris Cité Gif-sur-Yvette France
| | - Fabienne Picard
- Department of Neurology; University Hospitals of Geneva and Medical School of Geneva; Geneva Switzerland
| |
Collapse
|
16
|
D'Gama AM, Geng Y, Couto JA, Martin B, Boyle EA, LaCoursiere CM, Hossain A, Hatem NE, Barry BJ, Kwiatkowski DJ, Vinters HV, Barkovich AJ, Shendure J, Mathern GW, Walsh CA, Poduri A. Mammalian target of rapamycin pathway mutations cause hemimegalencephaly and focal cortical dysplasia. Ann Neurol 2015; 77:720-5. [PMID: 25599672 DOI: 10.1002/ana.24357] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/19/2014] [Accepted: 12/24/2014] [Indexed: 12/21/2022]
Abstract
Focal malformations of cortical development, including focal cortical dysplasia (FCD) and hemimegalencephaly (HME), are important causes of intractable childhood epilepsy. Using targeted and exome sequencing on DNA from resected brain samples and nonbrain samples from 53 patients with FCD or HME, we identified pathogenic germline and mosaic mutations in multiple PI3K/AKT pathway genes in 9 patients, and a likely pathogenic variant in 1 additional patient. Our data confirm the association of DEPDC5 with sporadic FCD but also implicate this gene for the first time in HME. Our findings suggest that modulation of the mammalian target of rapamycin pathway may hold promise for malformation-associated epilepsy.
Collapse
Affiliation(s)
- Alissa M D'Gama
- Division of Genetics and Genomics, Department of Medicine, Manton Center for Orphan Disease Research and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA; Program in Medical and Population Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Saxena A, Sampson JR. Phenotypes associated with inherited and developmental somatic mutations in genes encoding mTOR pathway components. Semin Cell Dev Biol 2014; 36:140-6. [PMID: 25263008 DOI: 10.1016/j.semcdb.2014.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 09/12/2014] [Accepted: 09/18/2014] [Indexed: 11/29/2022]
Abstract
Mutations affecting the genes that encode upstream components in the mammalian (or mechanistic) target of rapamycin signalling pathway are associated with a group of rare inherited and developmental disorders that show overlapping clinical features. These include predisposition to a variety of benign or malignant tumours, localized overgrowth, developmental abnormalities of the brain, neurodevelopmental disorders and epilepsy. Many of these features have been linked to hyperactivation of signalling via mammalian target of rapamycin complex 1, suggesting that inhibitors of this complex such as rapamycin and its derivatives may offer new opportunities for therapy. In this review we describe this group of inherited and developmental disorders and discuss recent progress in their treatment via mTORC1 inhibition.
Collapse
Affiliation(s)
- Anurag Saxena
- Institute of Medical Genetics, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
| | - Julian R Sampson
- Institute of Medical Genetics, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| |
Collapse
|