1
|
Cases-Cunillera S, Quatraccioni A, Rossini L, Ruffolo G, Ono T, Baulac S, Auvin S, O'Brien TJ, Henshall DC, Akman Ö, Sankar R, Galanopoulou AS. WONOEP appraisal: The role of glial cells in focal malformations associated with early onset epilepsies. Epilepsia 2024. [PMID: 39401070 DOI: 10.1111/epi.18126] [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: 04/14/2024] [Revised: 08/29/2024] [Accepted: 08/29/2024] [Indexed: 10/15/2024]
Abstract
Epilepsy represents a common neurological disorder in patients with developmental brain lesions, particularly in association with malformations of cortical development and low-grade glioneuronal tumors. In these diseases, genetic and molecular alterations in neurons are increasingly discovered that can trigger abnormalities in the neuronal network, leading to higher neuronal excitability levels. However, the mechanisms underlying epilepsy cannot rely solely on assessing the neuronal component. Growing evidence has revealed the high degree of complexity underlying epileptogenic processes, in which glial cells emerge as potential modulators of neuronal activity. Understanding the role of glial cells in developmental brain lesions such as malformations of cortical development and low-grade glioneuronal tumors is crucial due to the high degree of pharmacoresistance characteristic of these lesions. This has prompted research to investigate the role of glial and immune cells in epileptiform activity to find new therapeutic targets that could be used as combinatorial drug therapy. In a special session of the XVI Workshop of the Neurobiology of Epilepsy (WONOEP, Talloires, France, July 2022) organized by the Neurobiology Commission of the International League Against Epilepsy, we discussed the evidence exploring the genetic and molecular mechanisms of glial cells and immune response and their implications in the pathogenesis of neurodevelopmental pathologies associated with early life epilepsies.
Collapse
Affiliation(s)
- Silvia Cases-Cunillera
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Neuronal Signaling in Epilepsy and Glioma, Paris, France
| | - Anne Quatraccioni
- Institute of Neuropathology, Section for Translational Epilepsy Research, Medical Faculty, University of Bonn, Bonn, Germany
| | - Laura Rossini
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, Rome, Italy
- IRCCS San Raffaele Roma, Rome, Italy
| | - Tomonori Ono
- Epilepsy Center, National Hospital Organization Nagasaki Medical Center, Ōmura, Japan
| | - Stéphanie Baulac
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, AP-HP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Stéphane Auvin
- Pediatric Neurology Department, AP-HP, Robert Debré University Hospital, CRMR épilepsies Rares, EpiCARE member, Paris, France
- Université Paris Cité, INSERM NeuroDiderot, Paris, France
- Institut Universitaire de France, Paris, France
| | - Terence J O'Brien
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Royal Melbourne Hospital, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Victoria, Australia
| | - David C Henshall
- Department of Physiology and Medical Physics, RCSI, University of Medicine and Health Sciences, Dublin, Ireland
| | - Özlem Akman
- Department of Physiology, Faculty of Medicine, Demiroglu Bilim University, Istanbul, Turkey
| | - Raman Sankar
- Department of Pediatrics and Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Aristea S Galanopoulou
- Saul R. Korey Department of Neurology, Isabelle Rapin Division of Child Neurology, Dominique P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, USA
| |
Collapse
|
2
|
Chalkley MBL, Guerin LN, Iyer T, Mallahan S, Nelson S, Sahin M, Hodges E, Ess KC, Ihrie RA. Human TSC2 Mutant Cells Exhibit Aberrations in Early Neurodevelopment Accompanied by Changes in the DNA Methylome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.04.597443. [PMID: 38895266 PMCID: PMC11185654 DOI: 10.1101/2024.06.04.597443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Tuberous Sclerosis Complex (TSC) is a debilitating developmental disorder characterized by a variety of clinical manifestations. While benign tumors in the heart, lungs, kidney, and brain are all hallmarks of the disease, the most severe symptoms of TSC are often neurological, including seizures, autism, psychiatric disorders, and intellectual disabilities. TSC is caused by loss of function mutations in the TSC1 or TSC2 genes and consequent dysregulation of signaling via mechanistic Target of Rapamycin Complex 1 (mTORC1). While TSC neurological phenotypes are well-documented, it is not yet known how early in neural development TSC1/2-mutant cells diverge from the typical developmental trajectory. Another outstanding question is the contribution of homozygous-mutant cells to disease phenotypes and whether such phenotypes are also seen in the heterozygous-mutant populations that comprise the vast majority of cells in patients. Using TSC patient-derived isogenic induced pluripotent stem cells (iPSCs) with defined genetic changes, we observed aberrant early neurodevelopment in vitro, including misexpression of key proteins associated with lineage commitment and premature electrical activity. These alterations in differentiation were coincident with hundreds of differentially methylated DNA regions, including loci associated with key genes in neurodevelopment. Collectively, these data suggest that mutation or loss of TSC2 affects gene regulation and expression at earlier timepoints than previously appreciated, with implications for whether and how prenatal treatment should be pursued.
Collapse
Affiliation(s)
- Mary-Bronwen L. Chalkley
- Department of Cell & Developmental Biology, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Lindsey N. Guerin
- Department of Biochemistry, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Tenhir Iyer
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Samantha Mallahan
- Department of Cell & Developmental Biology, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sydney Nelson
- Department of Cell & Developmental Biology, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Mustafa Sahin
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Emily Hodges
- Department of Biochemistry, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kevin C. Ess
- Department of Cell & Developmental Biology, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Denver, Colorado, United States of America
| | - Rebecca A. Ihrie
- Department of Cell & Developmental Biology, School of Medicine Basic Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| |
Collapse
|
3
|
Nguyen LH, Xu Y, Nair M, Bordey A. The mTOR pathway genes MTOR, Rheb, Depdc5, Pten, and Tsc1 have convergent and divergent impacts on cortical neuron development and function. eLife 2024; 12:RP91010. [PMID: 38411613 PMCID: PMC10942629 DOI: 10.7554/elife.91010] [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] [Indexed: 02/28/2024] Open
Abstract
Brain somatic mutations in various components of the mTOR complex 1 (mTORC1) pathway have emerged as major causes of focal malformations of cortical development and intractable epilepsy. While these distinct gene mutations converge on excessive mTORC1 signaling and lead to common clinical manifestations, it remains unclear whether they cause similar cellular and synaptic disruptions underlying cortical network hyperexcitability. Here, we show that in utero activation of the mTORC1 activator genes, Rheb or MTOR, or biallelic inactivation of the mTORC1 repressor genes, Depdc5, Tsc1, or Pten in the mouse medial prefrontal cortex leads to shared alterations in pyramidal neuron morphology, positioning, and membrane excitability but different changes in excitatory synaptic transmission. Our findings suggest that, despite converging on mTORC1 signaling, mutations in different mTORC1 pathway genes differentially impact cortical excitatory synaptic activity, which may confer gene-specific mechanisms of hyperexcitability and responses to therapeutic intervention.
Collapse
Affiliation(s)
- Lena H Nguyen
- Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at DallasRichardsonUnited States
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Youfen Xu
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Maanasi Nair
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Angelique Bordey
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| |
Collapse
|
4
|
Snyder HE, Jain P, RamachandranNair R, Jones KC, Whitney R. Genetic Advancements in Infantile Epileptic Spasms Syndrome and Opportunities for Precision Medicine. Genes (Basel) 2024; 15:266. [PMID: 38540325 PMCID: PMC10970414 DOI: 10.3390/genes15030266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/13/2024] [Accepted: 02/20/2024] [Indexed: 06/15/2024] Open
Abstract
Infantile epileptic spasms syndrome (IESS) is a devastating developmental epileptic encephalopathy (DEE) consisting of epileptic spasms, as well as one or both of developmental regression or stagnation and hypsarrhythmia on EEG. A myriad of aetiologies are associated with the development of IESS; broadly, 60% of cases are thought to be structural, metabolic or infectious in nature, with the remainder genetic or of unknown cause. Epilepsy genetics is a growing field, and over 28 copy number variants and 70 single gene pathogenic variants related to IESS have been discovered to date. While not exhaustive, some of the most commonly reported genetic aetiologies include trisomy 21 and pathogenic variants in genes such as TSC1, TSC2, CDKL5, ARX, KCNQ2, STXBP1 and SCN2A. Understanding the genetic mechanisms of IESS may provide the opportunity to better discern IESS pathophysiology and improve treatments for this condition. This narrative review presents an overview of our current understanding of IESS genetics, with an emphasis on animal models of IESS pathogenesis, the spectrum of genetic aetiologies of IESS (i.e., chromosomal disorders, single-gene disorders, trinucleotide repeat disorders and mitochondrial disorders), as well as available genetic testing methods and their respective diagnostic yields. Future opportunities as they relate to precision medicine and epilepsy genetics in the treatment of IESS are also explored.
Collapse
Affiliation(s)
- Hannah E. Snyder
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON L8N 3Z5, Canada (R.R.)
| | - Puneet Jain
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON M5G 1E8, Canada
| | - Rajesh RamachandranNair
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON L8N 3Z5, Canada (R.R.)
| | - Kevin C. Jones
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON L8N 3Z5, Canada (R.R.)
| | - Robyn Whitney
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON L8N 3Z5, Canada (R.R.)
| |
Collapse
|
5
|
Mohsin SN, Grezenko H, Khan S, Eshete FD, Shrestha S, Kamran M, Affaf M, Jama A, Gasim RW, Zubaer Ahmad D, Yadav I, Arif S, K C A, Khaliq AS. Bridging Development and Disruption: Comprehensive Insights into Focal Cortical Dysplasia and Epileptic Management. Cureus 2023; 15:e45996. [PMID: 37900524 PMCID: PMC10601976 DOI: 10.7759/cureus.45996] [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] [Accepted: 09/26/2023] [Indexed: 10/31/2023] Open
Abstract
Focal cortical dysplasia (FCD) is a prominent neurological disorder characterized by disruptions in localized brain cell organization and development. This narrative review delineates the multi-faceted nature of FCD, emphasizing its correlation with drug-resistant epilepsy, predominantly in children and young adults. We explore the historical context of FCD, highlighting its indispensable role in shaping our comprehension of epilepsy and cortical anomalies. The clinical spectrum of FCD is broad, encompassing diverse seizure patterns, cognitive impairments, and associated neuropsychiatric disorders. We underscore the importance of differential diagnosis, with techniques ranging from electroencephalogram (EEG) interpretations to microscopic evaluations, and discuss advanced diagnostic modalities, such as the 3T magnetic resonance imaging (MRI) epilepsy protocols. Therapeutically, while anti-seizure medications are often first-line interventions, surgically refractory cases necessitate more invasive procedures, underscoring the importance of individualized treatment. Furthermore, the review touches upon the prognostic aspects of FCD, highlighting the importance of personalized care regimens, and provides insights into emerging therapeutic avenues, including the potential of the mammalian target of rapamycin (mTOR) pathway. Conclusively, this review accentuates the complex relationship between brain development and epileptogenicity inherent to FCD and underscores the promise of future research in enhancing patient outcomes.
Collapse
Affiliation(s)
| | - Han Grezenko
- Translational Neuroscience, Barrow Neurological Institute, Phoenix, USA
| | - Saadia Khan
- Community Medicine, Khyber Girls Medical College, Peshawar, PAK
| | | | - Shraddha Shrestha
- Internal Medicine, Nepal Korea Friendship Municipality Hospital, Bhaktapur, NPL
| | | | - Maryam Affaf
- Internal Medicine, Women's Medical and Dental College, Abbottabad, PAK
| | - Ayat Jama
- Internal Medicine, Nishtar Medical University, Multan, PAK
| | - Rayan W Gasim
- Internal Medicine, University of Khartoum, Khartoum, SDN
| | | | - Indresh Yadav
- Internal Medicine, Samar Hospital and Research Center Pvt. Ltd., Janakpur, NPL
- Internal Medicine, Community Based Medical College, Mymensingh, BGD
| | - Sidra Arif
- Urology, Jinnah Postgraduate Medical Center, Karachi, PAK
| | - Anil K C
- Medicine and Surgery, Patan Academy of Health Sciences, Kathmandu, NPL
- Internal Medicine and Neurology, California Institute of Behavioral Neurosciences & Psychology, California, USA
| | | |
Collapse
|
6
|
Aquiles A, Fiordelisio T, Luna-Munguia H, Concha L. Altered functional connectivity and network excitability in a model of cortical dysplasia. Sci Rep 2023; 13:12335. [PMID: 37518675 PMCID: PMC10387479 DOI: 10.1038/s41598-023-38717-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/13/2023] [Indexed: 08/01/2023] Open
Abstract
Focal cortical dysplasias (FCDs) are malformations of cortical development that often result in medically refractory epilepsy, with a greater incidence in the pediatric population. The relationship between the disturbed cortical morphology and epileptogenic activity of FCDs remains unclear. We used the BCNU (carmustine 1-3-bis-chloroethyl-nitrosourea) animal model of cortical dysplasia to evaluate neuronal and laminar alterations and how these result in altered activity of intracortical networks in early life. We corroborated the previously reported morphological anomalies characteristic of the BCNU model, comprising slightly larger and rounder neurons and abnormal cortical lamination. Next, the neuronal activity of live cortical slices was evaluated through large field-of-view calcium imaging as well as the neuronal response to a stimulus that leads to cortical hyperexcitability (pilocarpine). Examination of the joint activity of neuronal calcium time series allowed us to identify intracortical communication patterns and their response to pilocarpine. The baseline power density distribution of neurons in the cortex of BCNU-treated animals was different from that of control animals, with the former showing no modulation after stimulus. Moreover, the intracortical communication pattern differed between the two groups, with cortexes from BCNU-treated animals displaying decreased inter-layer connectivity as compared to control animals. Our results indicate that the altered anatomical organization of the cortex of BCNU-treated rats translates into altered functional networks that respond abnormally to a hyperexcitable stimulus and highlight the role of network dysfunction in the pathophysiology of cortical dysplasia.
Collapse
Affiliation(s)
- A Aquiles
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Querétaro, Mexico
| | - T Fiordelisio
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia LaNSBioDyT, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - H Luna-Munguia
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Querétaro, Mexico
| | - L Concha
- Institute of Neurobiology, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Querétaro, Mexico.
| |
Collapse
|
7
|
Ramamurthy A, Carvill GL. Raptor Preys on mTOR Imbalance in Tuberous Sclerosis. Epilepsy Curr 2023; 23:193-195. [PMID: 37334409 PMCID: PMC10273816 DOI: 10.1177/15357597231176235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2023] Open
Abstract
Raptor Downregulation Rescues Neuronal Phenotypes in Mouse Models of Tuberous Sclerosis Complex Karalis V, Caval-Holme F, Bateup HS. Nat Commun. 2022;13(1):4665. doi:10.1038/S41467-022-31961-6 Tuberous Sclerosis Complex (TSC) is a neurodevelopmental disorder caused by mutations in the TSC1 or TSC2 genes, which encode proteins that negatively regulate mTOR complex 1 (mTORC1) signaling. Current treatment strategies focus on mTOR inhibition with rapamycin and its derivatives. While effective at improving some aspects of TSC, chronic rapamycin inhibits both mTORC1 and mTORC2 and is associated with systemic side-effects. It is currently unknown which mTOR complex is most relevant for TSC-related brain phenotypes. Here we used genetic strategies to selectively reduce neuronal mTORC1 or mTORC2 activity in mouse models of TSC. We find that reduction of the mTORC1 component Raptor, but not the mTORC2 component Rictor, rebalanced mTOR signaling in Tsc1 knock-out neurons. Raptor reduction was sufficient to improve several TSC-related phenotypes including neuronal hypertrophy, macrocephaly, impaired myelination, network hyperactivity, and premature mortality. Raptor downregulation represents a promising potential therapeutic intervention for the neurological manifestations of TSC.
Collapse
Affiliation(s)
- Aishwarya Ramamurthy
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine
| | - Gemma Louise Carvill
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine
| |
Collapse
|
8
|
Riikonen R. Biochemical mechanisms in pathogenesis of infantile epileptic spasm syndrome. Seizure 2023; 105:1-9. [PMID: 36634586 DOI: 10.1016/j.seizure.2023.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 01/01/2023] [Accepted: 01/05/2023] [Indexed: 01/09/2023] Open
Abstract
The molecular mechanisms leading to infantile epileptic spasm syndrome (IESS) remain obscure. The only common factor seems to be that the spasms are restricted to a limited period of infancy, during a certain maturational state. Here the current literature regarding the biochemical mechanisms of brain maturation in IESS is reviewed, and various hypotheses of the pathophysiology are put together. They include: (1) imbalance of inhibitory (NGF, IGF-1, ACTH, GABA) and excitatory factors (glutamate, nitrites) which distinguishes the different etiological subgroups, (2) abnormality of the hypothalamic pituitary adrenal (HPA) axis linking insults and early life stress, (3) inflammation (4) yet poorly known genetic and epigenetic factors, and (5) glucocorticoid and vigabatrin action on brain development, pinpointing at molecular targets of the pathophysiology from another angle. An altered maturational process may explain why so many, seemingly independent etiological factors lead to the same clinical syndrome and frequently to developmental delay. Understanding these factors can provide ideas for novel therapies.
Collapse
Affiliation(s)
- Raili Riikonen
- Children's Hospital, University of Eastern Finland and Kuopio University Hospital, Kuopio, Finland.
| |
Collapse
|
9
|
Kapar O, Gurkan ZM, Dolgun M, Sencer A, Gürses C, Bilgic B. Focal cortical dysplasia pathology: diagnostic difficulty, classification, and utility for pathogenesis. Neurosurg Focus 2022; 53:E6. [DOI: 10.3171/2022.7.focus21731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 07/21/2022] [Indexed: 11/05/2022]
Abstract
OBJECTIVE
In the histopathological examination of treatment-resistant epilepsy, focal cortical dysplasia (FCD) is the most common diagnosis in the pediatric group. FCD is classified histopathologically according to the International League Against Epilepsy (ILAE) classification. In the last decade since the ILAE classification has been released, molecular genetic studies have revealed mTOR pathway–related mutations as a major etiology. The objective of this study was to determine the incidence of FCD in treatment-resistant epilepsy patients, explore histomorphological and immunohistochemical features, examine clinicopathological correlation, demonstrate mTOR pathway activation using a pS6 antibody immunohistochemically, and try to introduce a candidate for possible targeted therapies.
METHODS
Paraffin blocks and slides of tissue from patients with treatment-resistant epilepsy were reexamined retrospectively. Histopathological subtypes of FCD were determined according to the ILAE classification. NeuN and neurofilament H (NF-H) staining were performed, and additionally a pS6 antibody was used to demonstrate mTOR pathway activation.
RESULTS
In 32 cases diagnosed with FCD, or 17.5% of 183 surgical epilepsy materials, there were no significant differences in the statistical analysis of clinical variables between the ILAE FCD subtypes. Recommended antibody NeuN revealed microcolumnar alignment in the FCD type Ia and IIIa groups and the loss of lamination in the type Ib group. Another recommended antibody, NF-H, was not found to be useful in discriminating between normal and dysmorphic neurons. pS6 expression, showing mTOR pathway activation, was observed in dysmorphic neurons and balloon cells in all FCD type II cases.
CONCLUSIONS
Significant pS6 expression in FCD type II represents the genomic nature of the disease noted in the literature. Nevertheless, the known MTOR gene and mTOR pathway–related mutations remain behind proportionally to explain the mTOR pathway activation in all FCD type II cases. Clinicopathologically and genetically integrated classification and usage of mTOR pathway inhibitors in treatment are expected as a recent evolution.
Collapse
Affiliation(s)
- Ozge Kapar
- Department of Pathology, Istanbul University
| | - Zahide Mail Gurkan
- Department of Neurology and Clinical Neurophysiology, Istanbul University
| | - Muge Dolgun
- Department of Neurosurgery, Sultangazi Haseki Training and Research Hospital
| | - Altay Sencer
- Department of Neurosurgery, Istanbul Faculty of Medicine, Istanbul University; and
| | - Candan Gürses
- Department of Neurology, Koc University, Istanbul, Turkey
| | | |
Collapse
|
10
|
Lee WS, Baldassari S, Stephenson SEM, Lockhart PJ, Baulac S, Leventer RJ. Cortical Dysplasia and the mTOR Pathway: How the Study of Human Brain Tissue Has Led to Insights into Epileptogenesis. Int J Mol Sci 2022; 23:1344. [PMID: 35163267 PMCID: PMC8835853 DOI: 10.3390/ijms23031344] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 02/01/2023] Open
Abstract
Type II focal cortical dysplasia (FCD) is a neuropathological entity characterised by cortical dyslamination with the presence of dysmorphic neurons only (FCDIIA) or the presence of both dysmorphic neurons and balloon cells (FCDIIB). The year 2021 marks the 50th anniversary of the recognition of FCD as a cause of drug resistant epilepsy, and it is now the most common reason for epilepsy surgery. The causes of FCD remained unknown until relatively recently. The study of resected human FCD tissue using novel genomic technologies has led to remarkable advances in understanding the genetic basis of FCD. Mechanistic parallels have emerged between these non-neoplastic lesions and neoplastic disorders of cell growth and differentiation, especially through perturbations of the mammalian target of rapamycin (mTOR) signalling pathway. This narrative review presents the advances through which the aetiology of FCDII has been elucidated in chronological order, from recognition of an association between FCD and the mTOR pathway to the identification of somatic mosaicism within FCD tissue. We discuss the role of a two-hit mechanism, highlight current challenges and future directions in detecting somatic mosaicism in brain and discuss how knowledge of FCD may inform novel precision treatments of these focal epileptogenic malformations of human cortical development.
Collapse
Affiliation(s)
- Wei Shern Lee
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville 3052, Australia; (W.S.L.); (S.E.M.S.); (P.J.L.)
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
| | - Sara Baldassari
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013 Paris, France;
| | - Sarah E. M. Stephenson
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville 3052, Australia; (W.S.L.); (S.E.M.S.); (P.J.L.)
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
| | - Paul J. Lockhart
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville 3052, Australia; (W.S.L.); (S.E.M.S.); (P.J.L.)
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
| | - Stéphanie Baulac
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013 Paris, France;
| | - Richard J. Leventer
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
- Murdoch Children’s Research Institute, Parkville 3052, Australia
- Department of Neurology, The Royal Children’s Hospital, Parkville 3052, Australia
| |
Collapse
|
11
|
Karalis V, Bateup HS. Current Approaches and Future Directions for the Treatment of mTORopathies. Dev Neurosci 2021; 43:143-158. [PMID: 33910214 PMCID: PMC8440338 DOI: 10.1159/000515672] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/13/2021] [Indexed: 11/19/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a kinase at the center of an evolutionarily conserved signaling pathway that orchestrates cell growth and metabolism. mTOR responds to an array of intra- and extracellular stimuli and in turn controls multiple cellular anabolic and catabolic processes. Aberrant mTOR activity is associated with numerous diseases, with particularly profound impact on the nervous system. mTOR is found in two protein complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which are governed by different upstream regulators and have distinct cellular actions. Mutations in genes encoding for mTOR regulators result in a collection of neurodevelopmental disorders known as mTORopathies. While these disorders can affect multiple organs, neuropsychiatric conditions such as epilepsy, intellectual disability, and autism spectrum disorder have a major impact on quality of life. The neuropsychiatric aspects of mTORopathies have been particularly challenging to treat in a clinical setting. Current therapeutic approaches center on rapamycin and its analogs, drugs that are administered systemically to inhibit mTOR activity. While these drugs show some clinical efficacy, adverse side effects, incomplete suppression of mTOR targets, and lack of specificity for mTORC1 or mTORC2 may limit their utility. An increased understanding of the neurobiology of mTOR and the underlying molecular, cellular, and circuit mechanisms of mTOR-related disorders will facilitate the development of improved therapeutics. Animal models of mTORopathies have helped unravel the consequences of mTOR pathway mutations in specific brain cell types and developmental stages, revealing an array of disease-related phenotypes. In this review, we discuss current progress and potential future directions for the therapeutic treatment of mTORopathies with a focus on findings from genetic mouse models.
Collapse
Affiliation(s)
- Vasiliki Karalis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
| |
Collapse
|
12
|
Sidira C, Vargiami E, Dragoumi P, Zafeiriou DI. Hemimegalencephaly and tuberous sclerosis complex: A rare yet challenging association. Eur J Paediatr Neurol 2021; 30:58-65. [PMID: 33387903 DOI: 10.1016/j.ejpn.2020.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/20/2020] [Accepted: 12/17/2020] [Indexed: 12/18/2022]
Abstract
Hemimegalencephaly is a rare malformation of cortical development characterised by enlargement of one cerebral hemisphere. The association between hemimegalencephaly and tuberous sclerosis complex, an autosomal dominant genetic disorder, is uncommon and has so far been reported only in a few cases. Intractable epilepsy and severe developmental delay are typical clinical manifestations. Aberrant activation of the mTOR signalling pathway is considered to be the hallmark of the pathogenesis of these two disorders. Thus, mTOR inhibitors such as everolimus represent a promising therapeutic approach to mTOR-associated manifestations. We present a thorough literature review of the association between hemimegaloencephaly and tuberous sclerosis complex.
Collapse
Affiliation(s)
- Christina Sidira
- 1st Paediatric Department, Developmental Centre "A. Fokas", Aristotle University of Thessaloniki, "Hippokration" General Hospital, Thessaloniki, Greece
| | - Efthymia Vargiami
- 1st Paediatric Department, Developmental Centre "A. Fokas", Aristotle University of Thessaloniki, "Hippokration" General Hospital, Thessaloniki, Greece
| | - Pinelopi Dragoumi
- 1st Paediatric Department, Developmental Centre "A. Fokas", Aristotle University of Thessaloniki, "Hippokration" General Hospital, Thessaloniki, Greece
| | - Dimitrios I Zafeiriou
- 1st Paediatric Department, Developmental Centre "A. Fokas", Aristotle University of Thessaloniki, "Hippokration" General Hospital, Thessaloniki, Greece.
| |
Collapse
|
13
|
Wu K, Yue J, Shen K, He J, Zhu G, Liu S, Zhang C, Yang H. Increased expression of fibroblast growth factor 13 in cortical lesions of the focal cortical dysplasia. Brain Res Bull 2020; 168:36-44. [PMID: 33285262 DOI: 10.1016/j.brainresbull.2020.11.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/11/2020] [Accepted: 11/25/2020] [Indexed: 02/08/2023]
Abstract
Focal cortical dysplasias (FCDs) are well recognized as important causes of medically intractable epilepsy in both children and adults. To explore the potential role of fibroblast growth factor 13 (FGF13) in intractable epilepsy caused by FCDs, we examined the expression of FGF13 in cortical lesions from 23 patients with FCD type Ia (FCDIa), 24 patients with FCD type IIa (FCDIIa), and 12 patients with FCD type IIb (FCDIIb), and we compared the results with the FGF13 expression levels in control cortex (CTX) brain tissues from 12 nonepileptic normal subjects. Both the mRNA levels and protein levels of FGF13 were significantly higher in the cortical lesions from patients with FCD than in the control cortices. The immunohistochemical results showed that strong FGF13 immunoreactivity was observed in misshapen cells, including neuronal microcolumns, hypertrophic neurons, dysmorphic neurons, and most balloon cells. Moreover, double-label immunofluorescence analyses confirmed that FGF13 was mainly localized in neurons and nearly absent in glia-like cells. Taken together, our results suggest that the overexpression of FGF13 in FCDs and the cell-specific distribution patterns of FGF13 in misshapen neurons in FCDs could potentially contribute to intractable epilepsy caused by FCDs.
Collapse
Affiliation(s)
- Kefu Wu
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Jiong Yue
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Kaifeng Shen
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Jiaojiang He
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Gang Zhu
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Shiyong Liu
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Chunqing Zhang
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China.
| | - Hui Yang
- Epilepsy Research Center of PLA, Department of Neurosurgery, Xinqiao Hospital, Army Medical University, Chongqing, China.
| |
Collapse
|
14
|
Affiliation(s)
- Peter B Crino
- Department of Neurology 12264University of Maryland School of Medicine
| |
Collapse
|
15
|
Zhu L, Chen L, Xu P, Lu D, Dai S, Zhong L, Han Y, Zhang M, Xiao B, Chang L, Wu Q. Genetic and molecular basis of epilepsy-related cognitive dysfunction. Epilepsy Behav 2020; 104:106848. [PMID: 32028124 DOI: 10.1016/j.yebeh.2019.106848] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/06/2019] [Accepted: 12/06/2019] [Indexed: 02/02/2023]
Abstract
Epilepsy is a common neurological disease characterized by recurrent seizures. About 70 million people were affected by epilepsy or epileptic seizures. Epilepsy is a complicated complex or symptomatic syndromes induced by structural, functional, and genetic causes. Meanwhile, several comorbidities are accompanied by epileptic seizures. Cognitive dysfunction is a long-standing complication associated with epileptic seizures, which severely impairs quality of life. Although the definitive pathogenic mechanisms underlying epilepsy-related cognitive dysfunction remain unclear, accumulating evidence indicates that multiple risk factors are probably involved in the development and progression of cognitive dysfunction in patients with epilepsy. These factors include the underlying etiology, recurrent seizures or status epilepticus, structural damage that induced secondary epilepsy, genetic variants, and molecular alterations. In this review, we summarize several theories that may explain the genetic and molecular basis of epilepsy-related cognitive dysfunction.
Collapse
Affiliation(s)
- Lin Zhu
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China
| | - Lu Chen
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China
| | - Puying Xu
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China
| | - Di Lu
- Biomedicine Engineering Research Center, Kunming Medical University, 1168 Chun Rong West Road, Kunming, Yunnan 650500, PR China
| | - Shujuan Dai
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China
| | - Lianmei Zhong
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China
| | - Yanbing Han
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China
| | - Mengqi Zhang
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiang Ya Road, Changsha, Hunan 410008, PR China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, 87 Xiang Ya Road, Changsha, Hunan 410008, PR China
| | - Lvhua Chang
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China.
| | - Qian Wu
- Department of Neurology, First Affiliated Hospital, Kunming Medical University, 295 Xi Chang Road, Kunming, Yunnan 650032, PR China.
| |
Collapse
|
16
|
Mühlebner A, Bongaarts A, Sarnat HB, Scholl T, Aronica E. New insights into a spectrum of developmental malformations related to mTOR dysregulations: challenges and perspectives. J Anat 2019; 235:521-542. [PMID: 30901081 DOI: 10.1111/joa.12956] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2019] [Indexed: 12/20/2022] Open
Abstract
In recent years the role of the mammalian target of rapamycin (mTOR) pathway has emerged as crucial for normal cortical development. Therefore, it is not surprising that aberrant activation of mTOR is associated with developmental malformations and epileptogenesis. A broad spectrum of malformations of cortical development, such as focal cortical dysplasia (FCD) and tuberous sclerosis complex (TSC), have been linked to either germline or somatic mutations in mTOR pathway-related genes, commonly summarised under the umbrella term 'mTORopathies'. However, there are still a number of unanswered questions regarding the involvement of mTOR in the pathophysiology of these abnormalities. Therefore, a monogenetic disease, such as TSC, can be more easily applied as a model to study the mechanisms of epileptogenesis and identify potential new targets of therapy. Developmental neuropathology and genetics demonstrate that FCD IIb and hemimegalencephaly are the same diseases. Constitutive activation of mTOR signalling represents a shared pathogenic mechanism in a group of developmental malformations that have histopathological and clinical features in common, such as epilepsy, autism and other comorbidities. We seek to understand the effect of mTOR dysregulation in a developing cortex with the propensity to generate seizures as well as the aftermath of the surrounding environment, including the white matter.
Collapse
Affiliation(s)
- A Mühlebner
- Department of Neuropathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - A Bongaarts
- Department of Neuropathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - H B Sarnat
- Departments of Paediatrics, Pathology (Neuropathology) and Clinical Neurosciences, University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute (Owerko Centre), Calgary, AB, Canada
| | - T Scholl
- Department of Paediatric and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - E Aronica
- Department of Neuropathology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Stichting Epilepsie Instellingen Nederland (SEIN), Amsterdam, The Netherlands
| |
Collapse
|
17
|
Koh HY, Lee JH. Brain Somatic Mutations in Epileptic Disorders. Mol Cells 2018; 41:881-888. [PMID: 30352490 PMCID: PMC6199569 DOI: 10.14348/molcells.2018.0247] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/19/2018] [Accepted: 08/22/2018] [Indexed: 12/20/2022] Open
Abstract
During the cortical development, cells in the brain acquire somatic mutations that can be implicated in various neurodevelopmental disorders. There is increasing evidence that brain somatic mutations lead to sporadic form of epileptic disorders with previously unknown etiology. In particular, malformation of cortical developments (MCD), ganglioglioma (GG) associated with intractable epilepsy and non-lesional focal epilepsy (NLFE) are known to be attributable to brain somatic mutations in mTOR pathway genes and others. In order to identify such somatic mutations presenting as low-level in epileptic brain tissues, the mutated cells should be enriched and sequenced with high-depth coverage. Nevertheless, there are a lot of technical limitations to accurately detect low-level of somatic mutations. Also, it is important to validate whether identified somatic mutations are truly causative for epileptic seizures or not. Furthermore, it will be necessary to understand the molecular mechanism of how brain somatic mutations disturb neuronal circuitry since epilepsy is a typical example of neural network disorder. In this review, we overview current genetic techniques and experimental tools in neuroscience that can address the existence and significance of brain somatic mutations in epileptic disorders as well as their effect on neuronal circuitry.
Collapse
Affiliation(s)
- Hyun Yong Koh
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141,
Korea
| | - Jeong Ho Lee
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141,
Korea
- Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141,
Korea
| |
Collapse
|
18
|
Curatolo P, Moavero R, van Scheppingen J, Aronica E. mTOR dysregulation and tuberous sclerosis-related epilepsy. Expert Rev Neurother 2018; 18:185-201. [DOI: 10.1080/14737175.2018.1428562] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Paolo Curatolo
- Child Neurology and Psychiatry Unit, Systems Medicine Department, Tor Vergata University Hospital, Rome, Italy
| | - Romina Moavero
- Child Neurology and Psychiatry Unit, Systems Medicine Department, Tor Vergata University Hospital, Rome, Italy
- Child Neurology Unit, Neuroscience and Neurorehabilitation Department, “Bambino Gesù” Children’s Hospital, IRCCS, Rome, Italy
| | - Jackelien van Scheppingen
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), The Netherlands
| |
Collapse
|
19
|
Jeong A, Wong M. Targeting the Mammalian Target of Rapamycin for Epileptic Encephalopathies and Malformations of Cortical Development. J Child Neurol 2018; 33:55-63. [PMID: 29246093 PMCID: PMC5739082 DOI: 10.1177/0883073817696814] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Malformations of cortical development represent a common cause of epileptic encephalopathies and drug-resistant epilepsy in children. As current treatments are often ineffective, new therapeutic targets are needed for epileptic encephalopathies associated with cortical malformations. The mechanistic/mammalian target of rapamycin (mTOR) pathway constitutes a signaling pathway that drives cellular and molecular mechanisms of epileptogenesis in a variety of focal cortical malformations. mTOR inhibitors prevent epilepsy and associated pathogenic mechanisms of epileptogenesis in mouse models of tuberous sclerosis complex and are currently in clinical trials for drug-resistant seizures in these patients. A recent explosion of genetic studies has linked mutations in various genes regulating the mTOR pathway to other cortical malformations, such as focal cortical dysplasia and hemimegalencephaly. Thus, mTOR inhibitors represent promising candidates as novel antiseizure and antiepileptogenic therapies for epilepsy associated with a spectrum of cortical malformations.
Collapse
Affiliation(s)
- Anna Jeong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Michael Wong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| |
Collapse
|
20
|
Abstract
Epilepsy is one of the most common neurologic disorders, affecting about 50 million people worldwide. The disease is characterized by recurrent seizures, which are due to aberrant neuronal networks resulting in synchronous discharges. The term epilepsy encompasses a large spectrum of syndromes and diseases with different etiopathogenesis. The recent development of imaging and epilepsy surgery techniques is now enabling the identification of structural abnormalities that are part of the epileptic network, and the removal of these lesions may result in control of seizures. Access of this clinically well-characterized neurosurgical material has provided neuropathologists with the opportunity to study a variety of structural brain abnormalities associated with epilepsy, by combining traditional routine histopathologic methods with molecular genetics and functional analysis of the resected tissue. This approach has contributed greatly to a better diagnosis and classification of these structural lesions, and has provided important new insights into their pathogenesis and epileptogenesis. The present chapter provides a detailed description of the large spectrum of histopathologic findings encountered in epilepsy surgery patients, addressing in particular the nonneoplastic pathologies, including hippocampal sclerosis, malformations of cortical development, Sturge-Weber syndrome, and Rasmussen encephalitis, and reviews current knowledge regarding the underlying molecular pathomechanisms and cellular mechanisms mediating hyperexcitability.
Collapse
Affiliation(s)
- Eleonora Aronica
- Department of Neuropathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands; Stichting Epilepsie Instellingen Nederland, the Netherlands.
| | - Angelika Mühlebner
- Department of Neuropathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands
| |
Collapse
|
21
|
Telencephalic Flexure and Malformations of the Lateral Cerebral (Sylvian) Fissure. Pediatr Neurol 2016; 63:23-38. [PMID: 27590993 DOI: 10.1016/j.pediatrneurol.2016.05.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 05/04/2016] [Indexed: 11/20/2022]
Abstract
After sagittal division of the prosencephalon at 4.5 weeks of gestation, the early fetal cerebral hemisphere bends or rotates posteroventrally from seven weeks of gestation. The posterior pole of the telencephalon thus becomes not the occipital but the temporal lobe as the telencephalic flexure forms the operculum and finally the lateral cerebral or Sylvian fissure. The ventral part is infolded to become the insula. The frontal and temporal lips of the Sylvian fissure, as well as the insula, all derive from the ventral margin of the primitive telencephalon, hence may be influenced by genetic mutations with a ventrodorsal gradient of expression. The telencephalic flexure also contributes to a shift of the hippocampus from a dorsal to a ventral position, the early rostral pole of the hippocampus becoming caudal and dorsal becoming ventral. The occipital horn is the most recent recess of the lateral ventricle, hence most vulnerable to anatomic variations that affect the calcarine fissure. Many major malformations include lack of telencephalic flexure (holoprosencephaly, extreme micrencephaly) or dysplastic Sylvian fissure (lissencephalies, hemimegalencephaly, schizencephaly). Although fissures and sulci are genetically programmed, mechanical forces of growth and volume expansion are proposed to be mainly extrinsic (including ventricles) for fissures and intrinsic for sulci. In fetal hydrocephalus, the telencephalic flexure is less affected because ventricular dilatation occurs later in gestation. Flexures can be detected prenatally by ultrasound and fetal magnetic resonance imaging and should be described neuropathologically in cerebral malformations.
Collapse
|
22
|
Abstract
Malformations of cortical development (MCD) represent a major cause of developmental disabilities, severe epilepsy, and reproductive disadvantage. Genes that have been associated to MCD are mainly involved in cell proliferation and specification, neuronal migration, and late cortical organization. Lissencephaly-pachygyria-severe band heterotopia are diffuse neuronal migration disorders causing severe global neurological impairment. Abnormalities of the LIS1, DCX, ARX, RELN, VLDLR, ACTB, ACTG1, TUBG1, KIF5C, KIF2A, and CDK5 genes have been associated with these malformations. More recent studies have also established a relationship between lissencephaly, with or without associated microcephaly, corpus callosum dysgenesis as well as cerebellar hypoplasia, and at times, a morphological pattern consistent with polymicrogyria with mutations of several genes (TUBA1A, TUBA8, TUBB, TUBB2B, TUBB3, and DYNC1H1), regulating the synthesis and function of microtubule and centrosome key components and hence defined as tubulinopathies. MCD only affecting subsets of neurons, such as mild subcortical band heterotopia and periventricular heterotopia, have been associated with abnormalities of the DCX, FLN1A, and ARFGEF2 genes and cause neurological and cognitive impairment that vary from severe to mild deficits. Polymicrogyria results from abnormal late cortical organization and is inconstantly associated with abnormal neuronal migration. Localized polymicrogyria has been associated with anatomo-specific deficits, including disorders of language and higher cognition. Polymicrogyria is genetically heterogeneous, and only in a small minority of patients, a definite genetic cause has been identified. Megalencephaly with normal cortex or polymicrogyria by MRI imaging, hemimegalencephaly and focal cortical dysplasia can all result from mutations in genes of the PI3K-AKT-mTOR pathway. Postzygotic mutations have been described for most MCD and can be limited to the dysplastic tissue in the less diffuse forms.
Collapse
Affiliation(s)
- Elena Parrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Department of Neuroscience, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Valerio Conti
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Department of Neuroscience, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - William B Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, and Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Wash., USA
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Department of Neuroscience, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| |
Collapse
|
23
|
Song Y, Pimentel C, Walters K, Boller L, Ghiasvand S, Liu J, Staley KJ, Berdichevsky Y. Neuroprotective levels of IGF-1 exacerbate epileptogenesis after brain injury. Sci Rep 2016; 6:32095. [PMID: 27561791 PMCID: PMC4999804 DOI: 10.1038/srep32095] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 08/02/2016] [Indexed: 02/06/2023] Open
Abstract
Exogenous Insulin-Like Growth Factor-1 (IGF-1) is neuroprotective in animal models of brain injury, and has been considered as a potential therapeutic. Akt-mTOR and MAPK are downstream targets of IGF-1 signaling that are activated after brain injury. However, both brain injury and mTOR are linked to epilepsy, raising the possibility that IGF-1 may be epileptogenic. Here, we considered the role of IGF-1 in development of epilepsy after brain injury, using the organotypic hippocampal culture model of post-traumatic epileptogenesis. We found that IGF-1 was neuroprotective within a few days of injury but that long-term IGF-1 treatment was pro-epileptic. Pro-epileptic effects of IGF-1 were mediated by Akt-mTOR signaling. We also found that IGF-1 - mediated increase in epileptic activity led to neurotoxicity. The dualistic nature of effects of IGF-1 treatment demonstrates that anabolic enhancement through IGF-1 activation of mTOR cascade can be beneficial or harmful depending on the stage of the disease. Our findings suggest that epilepsy risk may need to be considered in the design of neuroprotective treatments for brain injury.
Collapse
Affiliation(s)
- Yu Song
- Bioengineering Program, Lehigh University, Bethlehem, PA 18015, USA
| | - Corrin Pimentel
- Bioengineering Program, Lehigh University, Bethlehem, PA 18015, USA
| | - Katherine Walters
- Integrated Degree in Engineering, Arts, and Sciences (IDEAS) Program, Lehigh University, PA 18015, USA
| | - Lauren Boller
- Bioengineering Program, Lehigh University, Bethlehem, PA 18015, USA
| | | | - Jing Liu
- Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA 18015, USA
| | - Kevin J Staley
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02129, USA.,Harvard Medical School, Boston, MA 02129, USA
| | - Yevgeny Berdichevsky
- Bioengineering Program, Lehigh University, Bethlehem, PA 18015, USA.,Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA 18015, USA
| |
Collapse
|
24
|
Kim J, Maeng JH, Lim JS, Son H, Lee J, Lee JH, Kim S. Vecuum: identification and filtration of false somatic variants caused by recombinant vector contamination. Bioinformatics 2016; 32:3072-3080. [PMID: 27334474 DOI: 10.1093/bioinformatics/btw383] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 06/14/2016] [Indexed: 11/14/2022] Open
Abstract
MOTIVATION Advances in sequencing technologies have remarkably lowered the detection limit of somatic variants to a low frequency. However, calling mutations at this range is still confounded by many factors including environmental contamination. Vector contamination is a continuously occurring issue and is especially problematic since vector inserts are hardly distinguishable from the sample sequences. Such inserts, which may harbor polymorphisms and engineered functional mutations, can result in calling false variants at corresponding sites. Numerous vector-screening methods have been developed, but none could handle contamination from inserts because they are focusing on vector backbone sequences alone. RESULTS We developed a novel method-Vecuum-that identifies vector-originated reads and resultant false variants. Since vector inserts are generally constructed from intron-less cDNAs, Vecuum identifies vector-originated reads by inspecting the clipping patterns at exon junctions. False variant calls are further detected based on the biased distribution of mutant alleles to vector-originated reads. Tests on simulated and spike-in experimental data validated that Vecuum could detect 93% of vector contaminants and could remove up to 87% of variant-like false calls with 100% precision. Application to public sequence datasets demonstrated the utility of Vecuum in detecting false variants resulting from various types of external contamination. AVAILABILITY AND IMPLEMENTATION Java-based implementation of the method is available at http://vecuum.sourceforge.net/ CONTACT: swkim@yuhs.acSupplementary information: Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Junho Kim
- Severance Biomedical Science Institute, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul 03722, South Korea
| | - Ju Heon Maeng
- Severance Biomedical Science Institute, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul 03722, South Korea
| | - Jae Seok Lim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 34141, South Korea
| | - Hyeonju Son
- Severance Biomedical Science Institute, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul 03722, South Korea
| | - Junehawk Lee
- Department of Convergence Technology Research, Korea Institute of Science and Technology Information, Daejeon 34141, South Korea
| | - Jeong Ho Lee
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 34141, South Korea
| | - Sangwoo Kim
- Severance Biomedical Science Institute, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul 03722, South Korea
| |
Collapse
|
25
|
Lee JH. Somatic mutations in disorders with disrupted brain connectivity. Exp Mol Med 2016; 48:e239. [PMID: 27282107 PMCID: PMC4929695 DOI: 10.1038/emm.2016.53] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 02/17/2016] [Indexed: 12/21/2022] Open
Abstract
Mutations occur during cell division in all somatic lineages. Because neurogenesis persists throughout human life, somatic mutations in the brain arise during development and accumulate with the aging process. The human brain consists of 100 billion neurons that form an extraordinarily intricate network of connections to achieve higher level cognitive functions. Due to this network architecture, perturbed neuronal functions are rarely restricted to a focal area; instead, they are often spread via the neuronal network to affect other connected areas. Although somatic diversity is an evident feature of the brain, the extent to which somatic mutations affect the neuronal structure and function and their contribution to neurological disorders associated with disrupted brain connectivity remain largely unexplored. Notably, recent reports indicate that brain somatic mutations can indeed play a critical role that leads to the structural and functional abnormalities of the brain observed in several neurodevelopmental disorders. Here, I review the extent and significance of brain somatic mutations and provide my perspective regarding these mutations as potential molecular lesions underlying relatively common conditions with disrupted brain connectivity. Moreover, I discuss emerging technical platforms that will facilitate the detection of low-frequency somatic mutations and validate the biological functions of the identified mutations in the context of brain connectivity.
Collapse
Affiliation(s)
- Jeong Ho Lee
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| |
Collapse
|
26
|
Sun FJ, Zhang CQ, Chen X, Wei YJ, Li S, Liu SY, Zang ZL, He JJ, Guo W, Yang H. Downregulation of CD47 and CD200 in patients with focal cortical dysplasia type IIb and tuberous sclerosis complex. J Neuroinflammation 2016; 13:85. [PMID: 27095555 PMCID: PMC4837553 DOI: 10.1186/s12974-016-0546-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 04/11/2016] [Indexed: 12/20/2022] Open
Abstract
Background Focal cortical dysplasia type IIb (FCD IIb) and tuberous sclerosis complex (TSC) are well-recognized causes of chronic intractable epilepsy in children. Accumulating evidence suggests that activation of the microglia/macrophage and concomitant inflammatory response in FCD IIb and TSC may contribute to the initiation and recurrence of seizures. The membrane glycoproteins CD47 and CD200, which are highly expressed in neurons and other cells, mediate inhibitory signals through their receptors, signal regulatory protein α (SIRP-α) and CD200R, respectively, in microglia/macrophages. We investigate the levels and expression pattern of CD47/SIRP-α and CD200/CD200R in surgically resected brain tissues from patients with FCD IIb and TSC, and the potential effect of soluble human CD47 Fc and CD200 Fc on the inhibition of several proinflammatory cytokines associated with FCD IIb and TSC in living epileptogenic brain slices in vitro. The level of interleukin-4 (IL-4), a modulator of CD200, was also investigated. Methods Twelve FCD IIb (range 1.8–9.5 years), 13 TSC (range 1.5–10 years) patients, and 6 control cases (range 1.5–11 years) were enrolled. The levels of CD47/SIRP-α and CD200/CD200R were assessed by quantitative real-time polymerase chain reaction and western blot. The expression pattern of CD47/SIRP-α and CD200/CD200R was investigated by immunohistochemical analysis, and the cytokine concentrations were measured by enzyme-linked immune-sorbent assays. Results Both the messenger RNA and protein levels of CD47, SIRP-α, and CD200, as well as the mRNA level of IL-4, were downregulated in epileptogenic lesions of FCD IIb and TSC compared with the control specimens, whereas CD200R levels were not significantly changed. CD47, SIRP-α, and CD200 were decreasingly expressed in dysmorphic neuron, balloon cells, and giant cells. CD47 Fc and CD200 Fc could inhibit IL-6 release but did not suppress IL-1β or IL-17 production. Conclusions Our results suggest that microglial activation may be partially caused by CD47/SIRP-α- and CD200/CD200R-mediated reductions in the immune inhibitory pathways within FCD IIb and TSC cortical lesions where chronic neuroinflammation has been established. Upregulation or activation of CD47/SIRP-α and CD200/CD200R may have therapeutic potential for controlling neuroinflammation in human FCD IIb and TSC. Electronic supplementary material The online version of this article (doi:10.1186/s12974-016-0546-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Fei-Ji Sun
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Chun-Qing Zhang
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Xin Chen
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Yu-Jia Wei
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Song Li
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Shi-Yong Liu
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Zhen-le Zang
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China
| | - Jiao-Jiang He
- Department of Neurosurgery, Lanzhou General Hospital of Chinese People's Liberation Army, Lanzhou, China
| | - Wei Guo
- Department of Neurosurgery, Tangdu Hospital, Fourth Military Medical University, Xian, China
| | - Hui Yang
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, 2-V Xinqiao Street, Chongqing, 400037, China.
| |
Collapse
|
27
|
Chong J, Caputo V, Phelps I, Stella L, Worgan L, Dempsey J, Nguyen A, Leuzzi V, Webster R, Pizzuti A, Marvin C, Ishak G, Ardern-Holmes S, Richmond Z, Bamshad M, Ortiz-Gonzalez X, Tartaglia M, Chopra M, Doherty D, Doherty D. Recessive Inactivating Mutations in TBCK, Encoding a Rab GTPase-Activating Protein, Cause Severe Infantile Syndromic Encephalopathy. Am J Hum Genet 2016; 98:772-81. [PMID: 27040692 DOI: 10.1016/j.ajhg.2016.01.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 01/27/2016] [Indexed: 11/26/2022] Open
Abstract
Infantile encephalopathies are a group of clinically and biologically heterogeneous disorders for which the genetic basis remains largely unknown. Here, we report a syndromic neonatal encephalopathy characterized by profound developmental disability, severe hypotonia, seizures, diminished respiratory drive requiring mechanical ventilation, brain atrophy, dysgenesis of the corpus callosum, cerebellar vermis hypoplasia, and facial dysmorphism. Biallelic inactivating mutations in TBCK (TBC1-domain-containing kinase) were independently identified by whole-exome sequencing as the cause of this condition in four unrelated families. Matching these families was facilitated by the sharing of phenotypic profiles and WES data in a recently released web-based tool (Geno2MP) that links phenotypic information to rare variants in families with Mendelian traits. TBCK is a putative GTPase-activating protein (GAP) for small GTPases of the Rab family and has been shown to control cell growth and proliferation, actin-cytoskeleton dynamics, and mTOR signaling. Two of the three mutations (c.376C>T [p.Arg126(∗)] and c.1363A>T [p.Lys455(∗)]) are predicted to truncate the protein, and loss of the major TBCK isoform was confirmed in primary fibroblasts from one affected individual. The third mutation, c.1532G>A (p.Arg511His), alters a conserved residue within the TBC1 domain. Structural analysis implicated Arg511 as a required residue for Rab-GAP function, and in silico homology modeling predicted impaired GAP function in the corresponding mutant. These results suggest that loss of Rab-GAP activity is the underlying mechanism of disease. In contrast to other disorders caused by dysregulated mTOR signaling associated with focal or global brain overgrowth, impaired TBCK function results in progressive loss of brain volume.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Dan Doherty
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA; Division of Genetic Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA.
| |
Collapse
|
28
|
Matsushita Y, Sakai Y, Shimmura M, Shigeto H, Nishio M, Akamine S, Sanefuji M, Ishizaki Y, Torisu H, Nakabeppu Y, Suzuki A, Takada H, Hara T. Hyperactive mTOR signals in the proopiomelanocortin-expressing hippocampal neurons cause age-dependent epilepsy and premature death in mice. Sci Rep 2016; 6:22991. [PMID: 26961412 PMCID: PMC4785342 DOI: 10.1038/srep22991] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/25/2016] [Indexed: 12/28/2022] Open
Abstract
Epilepsy is a frequent comorbidity in patients with focal cortical dysplasia (FCD). Recent studies utilizing massive sequencing data identified subsets of genes that are associated with epilepsy and FCD. AKT and mTOR-related signals have been recently implicated in the pathogenic processes of epilepsy and FCD. To clarify the functional roles of the AKT-mTOR pathway in the hippocampal neurons, we generated conditional knockout mice harboring the deletion of Pten (Pten-cKO) in Proopiomelanocortin-expressing neurons. The Pten-cKO mice developed normally until 8 weeks of age, then presented generalized seizures at 8–10 weeks of age. Video-monitored electroencephalograms detected paroxysmal discharges emerging from the cerebral cortex and hippocampus. These mice showed progressive hypertrophy of the dentate gyrus (DG) with increased expressions of excitatory synaptic markers (Psd95, Shank3 and Homer). In contrast, the expression of inhibitory neurons (Gad67) was decreased at 6–8 weeks of age. Immunofluorescence studies revealed the abnormal sprouting of mossy fibers in the DG of the Pten-cKO mice prior to the onset of seizures. The treatment of these mice with an mTOR inhibitor rapamycin successfully prevented the development of seizures and reversed these molecular phenotypes. These data indicate that the mTOR pathway regulates hippocampal excitability in the postnatal brain.
Collapse
Affiliation(s)
- Yuki Matsushita
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasunari Sakai
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Mitsunori Shimmura
- Department of Neurology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Hiroshi Shigeto
- Department of Neurology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Miki Nishio
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Satoshi Akamine
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Masafumi Sanefuji
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yoshito Ishizaki
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Hiroyuki Torisu
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Akira Suzuki
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Hidetoshi Takada
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Toshiro Hara
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| |
Collapse
|
29
|
Abstract
Focal cortical dysplasias are common malformations of cerebral cortical development and are highly associated with medically intractable epilepsy. They have been classified into neuropathological subtypes (type Ia, Ib, IIa, IIb, and III) based on the severity of cytoarchitectural disruption--tangential or radial dispersion, or loss of laminar structure--and the presence of unique cells types such as cytomegalic neurons or balloon cells. Most focal cortical dysplasias can be identified on neuroimaging and many require resective epilepsy surgery to cure refractory seizures. The pathogenesis of focal cortical dysplasias remains to be defined, although there is recent evidence to suggest that focal cortical dysplasias arise from de novo somatic mutations occurring during brain development. Some focal cortical dysplasia subtypes show a link to the mammalian target of rapamycin signaling cascade; this has now extended to other cortical malformations, including hemimegalencephaly.
Collapse
Affiliation(s)
- Peter B Crino
- Department of Neurology, Shriners Hospital Pediatric Research Center and Temple University, Philadelphia, Pennsylvania
| |
Collapse
|
30
|
Sarnat HB, Flores-Sarnat L. Infantile tauopathies: Hemimegalencephaly; tuberous sclerosis complex; focal cortical dysplasia 2; ganglioglioma. Brain Dev 2015; 37:553-62. [PMID: 25451314 DOI: 10.1016/j.braindev.2014.08.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/31/2014] [Accepted: 08/04/2014] [Indexed: 11/16/2022]
Abstract
Tau is a normal microtubule-associated protein; mutations to phosphorylated or acetylated forms are neurotoxic. In many dementias of adult life tauopathies cause neuronal degeneration. Four developmental disorders of the fetal and infant brain are presented, each of which exhibits up-regulation of tau. Microtubules are cytoskeletal structures that provide the strands of mitotic spindles and specify cellular polarity, growth, lineage, differentiation, migration and axonal transport of molecules. Phosphorylated tau is abnormal in immature as in mature neurons. Several malformations are demonstrated in which upregulated tau may be important in pathogenesis. All produce highly epileptogenic cortical foci. The prototype infantile tauopathy is (1) hemimegalencephaly (HME); normal tau is degraded by a mutant AKT3 or AKT1 gene as the aetiology of focal somatic mosaicism in the periventricular neuroepithelium. HME may be isolated or associated with neurocutaneous syndromes, particularly epidermal naevus syndromes, also due to somatic mutations. Other tauopathies of early life include: (2) tuberous sclerosis complex; (3) focal cortical dysplasia type 2b (FCD2b); and (4) ganglioglioma, a tumor with dysplastic neurons and neoplastic glial cells. Pathological tau in these infantile cases alters cellular growth and architecture, synaptic function and tissue organization, but does not cause neuronal loss. All infantile tauopathies are defined neuropathologically as a tetrad of (1) dysmorphic and megalocytic neurons; (2) activation of the mTOR signaling pathway; (3) post-zygotic somatic mosaicism; and (4) upregulation of phosphorylated tau. HME and FCD2b may be the same disorder with different timing of the somatic mutation in the mitotic cycles of the neuroepithelium. HME and FCD2b may be the same disorder with different timing of the somatic mutation in the mitotic cycles of the neuroepithelium. Tauopathies must be considered in infantile neurological disease and no longer restricted to adult dementias. The mTOR inhibitor everolimus, already demonstrated to be effective in TSC, also may be a potential treatment in other infantile tauopathies.
Collapse
Affiliation(s)
- Harvey B Sarnat
- Department of Paediatrics, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Foundation, Calgary, Alberta, Canada; Department of Pathology (Neuropathology), University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Foundation, Calgary, Alberta, Canada; Department of Clinical Neurosciences, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Foundation, Calgary, Alberta, Canada.
| | - Laura Flores-Sarnat
- Department of Paediatrics, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Foundation, Calgary, Alberta, Canada; Department of Clinical Neurosciences, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Foundation, Calgary, Alberta, Canada
| |
Collapse
|
31
|
Baynam G, Overkov A, Davis M, Mina K, Schofield L, Allcock R, Laing N, Cook M, Dawkins H, Goldblatt J. A germline MTOR mutation in Aboriginal Australian siblings with intellectual disability, dysmorphism, macrocephaly, and small thoraces. Am J Med Genet A 2015; 167:1659-67. [PMID: 25851998 DOI: 10.1002/ajmg.a.37070] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 03/06/2015] [Indexed: 11/07/2022]
Abstract
We report on three Aboriginal Australian siblings with a unique phenotype which overlaps with known megalencephaly syndromes and RASopathies, including Costello syndrome. A gain-of-function mutation in MTOR was identified and represents the first reported human condition due to a germline, familial MTOR mutation. We describe the findings in this family to highlight that (i) the path to determination of pathogenicity was confounded by the lack of genomic reference data for Australian Aboriginals and that (ii) the disease biology, functional analyses in this family, and studies on the tuberous sclerosis complex support consideration of an mTOR inhibitor as a therapeutic agent.
Collapse
Affiliation(s)
- Gareth Baynam
- Genetic Services of Western Australia, Princess Margaret and King Edward Memorial Hospitals, Perth, Western Australia, Australia.,School of Paediatrics and Child Health, University of Western Australia, Perth, Western Australia, Australia.,Office of Population Health Genomics, Department of Health, Public Health and Clinical Services Division, Government of Western Australia, Perth, Western Australia, Australia.,Institute for Immunology and Infectious Diseases, Murdoch University, Perth, Western Australia, Australia.,Telethon Kids Institute, Perth, Western Australia, Australia
| | - Angela Overkov
- Genetic Services of Western Australia, Princess Margaret and King Edward Memorial Hospitals, Perth, Western Australia, Australia
| | - Mark Davis
- School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia, Australia.,Diagnostic Genomics, PathWest Laboratory Medicine, QEII Medical Centre, Perth, Western Australia, Australia
| | - Kym Mina
- School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia, Australia.,Diagnostic Genomics, PathWest Laboratory Medicine, QEII Medical Centre, Perth, Western Australia, Australia
| | - Lyn Schofield
- Genetic Services of Western Australia, Princess Margaret and King Edward Memorial Hospitals, Perth, Western Australia, Australia.,Institute for Immunology and Infectious Diseases, Murdoch University, Perth, Western Australia, Australia
| | - Richard Allcock
- School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia, Australia.,Diagnostic Genomics, PathWest Laboratory Medicine, QEII Medical Centre, Perth, Western Australia, Australia
| | - Nigel Laing
- Harry Perkins Institute of Medical Research, Perth, Western Australia, Australia
| | - Matthew Cook
- Department of Immunology, John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia.,Australia and Translational Research Unit, Canberra Hospital, Canberra, Australian Capital Territory, Australia
| | - Hugh Dawkins
- School of Paediatrics and Child Health, University of Western Australia, Perth, Western Australia, Australia.,School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia, Australia.,Centre for Comparative Genomics, Murdoch University, Perth, Western Australia, Australia.,Centre for Population Health Research, Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
| | - Jack Goldblatt
- Genetic Services of Western Australia, Princess Margaret and King Edward Memorial Hospitals, Perth, Western Australia, Australia.,School of Paediatrics and Child Health, University of Western Australia, Perth, Western Australia, Australia.,Office of Population Health Genomics, Department of Health, Public Health and Clinical Services Division, Government of Western Australia, Perth, Western Australia, Australia
| |
Collapse
|
32
|
Crino PB. mTOR signaling in epilepsy: insights from malformations of cortical development. Cold Spring Harb Perspect Med 2015; 5:5/4/a022442. [PMID: 25833943 DOI: 10.1101/cshperspect.a022442] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Over the past decade enhanced activation of the mammalian target of rapamycin (mTOR)-signaling cascade has been identified in focal malformations of cortical development (MCD) subtypes, which have been collectively referred to as "mTORopathies." Mutations in mTOR regulatory genes (e.g., TSC1, TSC2, AKT3, DEPDC5) have been associated with several focal MCD highly associated with epilepsy such as tuberous sclerosis complex (TSC), hemimegalencephaly (HME; brain malformation associated with dramatic enlargement of one brain hemisphere), and cortical dysplasia. mTOR plays important roles in the regulation of cell division, growth, and survival, and, thus, aberrant activation of the cascade during cortical development can cause dramatic alterations in cell size, cortical lamination, and axon and dendrite outgrowth often observed in focal MCD. Although it is widely believed that structural alterations induced by hyperactivated mTOR signaling are critical for epileptogenesis, newer evidence suggests that mTOR activation on its own may enhance neuronal excitability. Clinical trials with mTOR inhibitors have shown efficacy in the treatment of seizures associated with focal MCD.
Collapse
Affiliation(s)
- Peter B Crino
- Shriners Hospital Pediatric Research Center and Department of Neurology, Temple University, Philadelphia, Pennsylvania 19140
| |
Collapse
|
33
|
Lim JS, Kim WI, Kang HC, Kim SH, Park AH, Park EK, Cho YW, Kim S, Kim HM, Kim JA, Kim J, Rhee H, Kang SG, Kim HD, Kim D, Kim DS, Lee JH. Brain somatic mutations in MTOR cause focal cortical dysplasia type II leading to intractable epilepsy. Nat Med 2015; 21:395-400. [PMID: 25799227 DOI: 10.1038/nm.3824] [Citation(s) in RCA: 345] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/12/2015] [Indexed: 12/18/2022]
Abstract
Focal cortical dysplasia type II (FCDII) is a sporadic developmental malformation of the cerebral cortex characterized by dysmorphic neurons, dyslamination and medically refractory epilepsy. It has been hypothesized that FCD is caused by somatic mutations in affected regions. Here, we used deep whole-exome sequencing (read depth, 412-668×) validated by site-specific amplicon sequencing (100-347,499×) in paired brain-blood DNA from four subjects with FCDII and uncovered a de novo brain somatic mutation, mechanistic target of rapamycin (MTOR) c.7280T>C (p.Leu2427Pro) in two subjects. Deep sequencing of the MTOR gene in an additional 73 subjects with FCDII using hybrid capture and PCR amplicon sequencing identified eight different somatic missense mutations found in multiple brain tissue samples of ten subjects. The identified mutations accounted for 15.6% of all subjects with FCDII studied (12 of 77). The identified mutations induced the hyperactivation of mTOR kinase. Focal cortical expression of mutant MTOR by in utero electroporation in mice was sufficient to disrupt neuronal migration and cause spontaneous seizures and cytomegalic neurons. Inhibition of mTOR with rapamycin suppressed cytomegalic neurons and epileptic seizures. This study provides, to our knowledge, the first evidence that brain somatic activating mutations in MTOR cause FCD and identifies mTOR as a treatment target for intractable epilepsy in FCD.
Collapse
Affiliation(s)
- Jae Seok Lim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| | - Woo-il Kim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| | - Hoon-Chul Kang
- 1] Division of Pediatric Neurology, Department of Pediatrics, Pediatric Epilepsy Clinics, Severance Children's Hospital, Seoul, Korea. [2] Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Se Hoon Kim
- Department of Pathology, Brain Korea 21 project for medical science, Yonsei University College of Medicine, Seoul, Korea
| | - Ah Hyung Park
- Department of Biological Sciences, KAIST, Daejeon, Korea
| | - Eun Kyung Park
- 1] Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea. [2] Department of Neurosurgery, Pediatric Epilepsy Clinics, Brain Korea 21 project for medical science, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Young-Wook Cho
- Korea Basic Science Institute, Chuncheon Center, Chuncheon-si, Gangwon-do, Korea
| | - Sangwoo Kim
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Ho Min Kim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| | - Jeong A Kim
- 1] Division of Pediatric Neurology, Department of Pediatrics, Pediatric Epilepsy Clinics, Severance Children's Hospital, Seoul, Korea. [2] Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Junho Kim
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Hwanseok Rhee
- Macrogen Bioinformatics Center, Macrogen, Gasan-dong, Geumcheon-gu, Seoul, Korea
| | - Seok-Gu Kang
- 1] Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea. [2] Department of Neurosurgery, Pediatric Epilepsy Clinics, Brain Korea 21 project for medical science, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Heung Dong Kim
- 1] Division of Pediatric Neurology, Department of Pediatrics, Pediatric Epilepsy Clinics, Severance Children's Hospital, Seoul, Korea. [2] Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Daesoo Kim
- Department of Biological Sciences, KAIST, Daejeon, Korea
| | - Dong-Seok Kim
- 1] Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea. [2] Department of Neurosurgery, Pediatric Epilepsy Clinics, Brain Korea 21 project for medical science, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jeong Ho Lee
- Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea
| |
Collapse
|
34
|
Curatolo P. Mechanistic target of rapamycin (mTOR) in tuberous sclerosis complex-associated epilepsy. Pediatr Neurol 2015; 52:281-9. [PMID: 25591831 DOI: 10.1016/j.pediatrneurol.2014.10.028] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/29/2014] [Accepted: 10/29/2014] [Indexed: 01/12/2023]
Abstract
BACKGROUND Tuberous sclerosis complex is a multiorgan disease resulting from a mutation of one of two TSC genes. The two gene products form a functional complex that regulates the mTOR signaling pathway (mTOR initially represented mammalian target of rapamycin, but increasingly the term mechanistic target of rapamycin is used to reflect the ubiquitous occurrence of mTOR). Epilepsy is the most common neurological symptom of tuberous sclerosis complex, occurring in 80% to 90% of affected individuals over the course of their lifetimes and causing significant morbidity and mortality. The mechanistic target of rapamycin (mTOR) signaling pathway is intricately involved in multiple cellular functions--including protein synthesis, cell growth and proliferation, and synaptic plasticity--which may influence neuronal excitability and precipitate epileptogenesis. Recent preclinical and clinical studies have increased interest in the potential role of mTOR inhibitors for the treatment of tuberous sclerosis complex-related epilepsy. METHODS Medline and PubMed database searches were used to identify relevant studies and other information on tuberous sclerosis complex-related epilepsies, the mTOR pathway, and current advances in treatment approaches. RESULTS Although current management strategies that provide symptomatic relief are effective at reducing the frequency of seizures in individuals with tuberous sclerosis complex, there is further room for the exploration of therapies that directly address hyperactive mTOR signaling--the underlying etiology of the disease. The role of the antiepileptic effect of mTOR inhibition was first demonstrated in knockout TSC1 mouse models. Additionally, several case studies demonstrated a positive effect on seizure frequency and severity in patients with pharmacoresistant epilepsy. In a phase 1/2 clinical trial with 28 patients, clinically relevant reduction in overall seizure frequency was documented in individuals treated with the mTOR inhibitor everolimus. In a phase 3 trial evaluating the role of everolimus in subependymal giant cell astrocytoma, seizures were a secondary end point. Because the median seizure frequency was zero in this study, the analysis was inconclusive. CONCLUSION Various preclinical models provide substantial evidence for the role of mTOR inhibition in the treatment of epilepsy in individuals with tuberous sclerosis complex. Preliminary clinical studies provide supportive evidence for a role of mTOR inhibition in the management of tuberous sclerosis complex-associated epilepsy and pave the way for new randomized placebo-controlled studies. This article reviews current treatment recommendations for the management of tuberous sclerosis complex-associated epilepsy as well as the rationale and evidence to support the use of mTOR inhibitors.
Collapse
Affiliation(s)
- Paolo Curatolo
- Child Neurology and Psychiatry Unit, Systems Medicine Department, Tor Vergata University of Rome, Rome, Italy.
| |
Collapse
|
35
|
Hester MS, Danzer SC. Hippocampal granule cell pathology in epilepsy - a possible structural basis for comorbidities of epilepsy? Epilepsy Behav 2014; 38:105-16. [PMID: 24468242 PMCID: PMC4110172 DOI: 10.1016/j.yebeh.2013.12.022] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 12/17/2013] [Accepted: 12/21/2013] [Indexed: 01/31/2023]
Abstract
Temporal lobe epilepsy in both animals and humans is characterized by abnormally integrated hippocampal dentate granule cells. Among other abnormalities, these cells make axonal connections with inappropriate targets, grow dendrites in the wrong direction, and migrate to ectopic locations. These changes promote the formation of recurrent excitatory circuits, leading to the appealing hypothesis that these abnormal cells may by epileptogenic. While this hypothesis has been the subject of intense study, less attention has been paid to the possibility that abnormal granule cells in the epileptic brain may also contribute to comorbidities associated with the disease. Epilepsy is associated with a variety of general findings, such as memory disturbances and cognitive dysfunction, and is often comorbid with a number of other conditions, including schizophrenia and autism. Interestingly, recent studies implicate disruption of common genes and gene pathways in all three diseases. Moreover, while neuropsychiatric conditions are associated with changes in a variety of brain regions, granule cell abnormalities in temporal lobe epilepsy appear to be phenocopies of granule cell deficits produced by genetic mouse models of autism and schizophrenia, suggesting that granule cell dysmorphogenesis may be a common factor uniting these seemingly diverse diseases. Disruption of common signaling pathways regulating granule cell neurogenesis may begin to provide mechanistic insight into the cooccurrence of temporal lobe epilepsy and cognitive and behavioral disorders.
Collapse
Affiliation(s)
- Michael S Hester
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Molecular and Developmental Biology Graduate Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Anesthesia, University of Cincinnati, Cincinnati, OH 45267, USA; Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45267, USA; Molecular and Developmental Biology Graduate Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
| |
Collapse
|
36
|
Abstract
Malformations of cortical development are common causes of developmental delay and epilepsy. Some patients have early, severe neurological impairment, but others have epilepsy or unexpected deficits that are detectable only by screening. The rapid evolution of molecular biology, genetics, and imaging has resulted in a substantial increase in knowledge about the development of the cerebral cortex and the number and types of malformations reported. Genetic studies have identified several genes that might disrupt each of the main stages of cell proliferation and specification, neuronal migration, and late cortical organisation. Many of these malformations are caused by de-novo dominant or X-linked mutations occurring in sporadic cases. Genetic testing needs accurate assessment of imaging features, and familial distribution, if any, and can be straightforward in some disorders but requires a complex diagnostic algorithm in others. Because of substantial genotypic and phenotypic heterogeneity for most of these genes, a comprehensive analysis of clinical, imaging, and genetic data is needed to properly define these disorders. Exome sequencing and high-field MRI are rapidly modifying the classification of these disorders.
Collapse
Affiliation(s)
- Renzo Guerrini
- Department of Neuroscience, Pharmacology and Child Health, Children's Hospital A Meyer and University of Florence, Florence, Italy; Stella Maris Foundation Research Institute, Pisa, Italy.
| | - William B Dobyns
- Departments of Pediatrics and Neurology, University of Washington, Seattle, WA, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| |
Collapse
|
37
|
Aronica E, Crino PB. Epilepsy related to developmental tumors and malformations of cortical development. Neurotherapeutics 2014; 11:251-68. [PMID: 24481729 PMCID: PMC3996119 DOI: 10.1007/s13311-013-0251-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Structural abnormalities of the brain are increasingly recognized in patients with neurodevelopmental delay and intractable focal epilepsies. The access to clinically well-characterized neurosurgical material has provided a unique opportunity to better define the neuropathological, neurochemical, and molecular features of epilepsy-associated focal developmental lesions. These studies help to further understand the epileptogenic mechanisms of these lesions. Neuropathological evaluation of surgical specimens from patients with epilepsy-associated developmental lesions reveals two major pathologies: focal cortical dysplasia and low-grade developmental tumors (glioneuronal tumors). In the last few years there have been major advances in the recognition of a wide spectrum of developmental lesions associated with a intractable epilepsy, including cortical tubers in patients with tuberous sclerosis complex and hemimegalencephaly. As an increasing number of entities are identified, the development of a unified and comprehensive classification represents a great challenge and requires continuous updates. The present article reviews current knowledge of molecular pathogenesis and the pathophysiological mechanisms of epileptogenesis in this group of developmental disorders. Both emerging neuropathological and basic science evidence will be analyzed, highlighting the involvement of different, but often converging, pathogenetic and epileptogenic mechanisms, which may create the basis for new therapeutic strategies in these disorders.
Collapse
Affiliation(s)
- Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands,
| | | |
Collapse
|
38
|
Lasarge CL, Danzer SC. Mechanisms regulating neuronal excitability and seizure development following mTOR pathway hyperactivation. Front Mol Neurosci 2014; 7:18. [PMID: 24672426 PMCID: PMC3953715 DOI: 10.3389/fnmol.2014.00018] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 02/27/2014] [Indexed: 01/19/2023] Open
Abstract
The phosphatidylinositol-3-kinase/phosphatase and tensin homolog (PTEN)-mammalian target of rapamycin (mTOR) pathway regulates a variety of neuronal functions, including cell proliferation, survival, growth, and plasticity. Dysregulation of the pathway is implicated in the development of both genetic and acquired epilepsies. Indeed, several causal mutations have been identified in patients with epilepsy, the most prominent of these being mutations in PTEN and tuberous sclerosis complexes 1 and 2 (TSC1, TSC2). These genes act as negative regulators of mTOR signaling, and mutations lead to hyperactivation of the pathway. Animal models deleting PTEN, TSC1, and TSC2 consistently produce epilepsy phenotypes, demonstrating that increased mTOR signaling can provoke neuronal hyperexcitability. Given the broad range of changes induced by altered mTOR signaling, however, the mechanisms underlying seizure development in these animals remain uncertain. In transgenic mice, cell populations with hyperactive mTOR have many structural abnormalities that support recurrent circuit formation, including somatic and dendritic hypertrophy, aberrant basal dendrites, and enlargement of axon tracts. At the functional level, mTOR hyperactivation is commonly, but not always, associated with enhanced synaptic transmission and plasticity. Moreover, these populations of abnormal neurons can affect the larger network, inducing secondary changes that may explain paradoxical findings reported between cell and network functioning in different models or at different developmental time points. Here, we review the animal literature examining the link between mTOR hyperactivation and epileptogenesis, emphasizing the impact of enhanced mTOR signaling on neuronal form and function.
Collapse
Affiliation(s)
- Candi L Lasarge
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA ; Department of Anesthesia, University of Cincinnati Cincinnati, OH, USA ; Department of Pediatrics, University of Cincinnati Cincinnati, OH, USA
| |
Collapse
|
39
|
Lee JY, Park AK, Lee ES, Park WY, Park SH, Choi JW, Phi JH, Wang KC, Kim SK. miRNA expression analysis in cortical dysplasia: Regulation of mTOR and LIS1 pathway. Epilepsy Res 2014; 108:433-41. [DOI: 10.1016/j.eplepsyres.2014.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 12/11/2013] [Accepted: 01/14/2014] [Indexed: 01/08/2023]
|
40
|
Leventer RJ, Jansen FE, Mandelstam SA, Ho A, Mohamed I, Sarnat HB, Kato M, Fukasawa T, Saitsu H, Matsumoto N, Itoh M, Kalnins RM, Chow CW, Harvey AS, Jackson GD, Crino PB, Berkovic SF, Scheffer IE. Is focal cortical dysplasia sporadic? Family evidence for genetic susceptibility. Epilepsia 2014; 55:e22-6. [DOI: 10.1111/epi.12533] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 02/01/2023]
Affiliation(s)
- Richard J. Leventer
- Department of Neurology; Royal Children's Hospital; Melbourne Victoria Australia
- Murdoch Childrens Research Institute; Melbourne Victoria Australia
- Department of Pediatrics; University of Melbourne; Melbourne Victoria Australia
| | - Floor E. Jansen
- Department of Pediatric Neurology; Rudolf Magnus Institute of Neurosciences; University Medical Center Utrecht; Utrecht The Netherlands
- Epilepsy Research Centre; University of Melbourne; Austin Health; Melbourne Victoria Australia
| | - Simone A. Mandelstam
- The Florey Institute of Neuroscience and Mental Health; Melbourne Victoria Australia
- Department of Radiology; University of Melbourne; Melbourne Victoria Australia
| | - Alice Ho
- Departments of Pediatrics and Clinical Neurosciences; Alberta Children's Hospital; University of Calgary; Calgary Alberta Canada
| | - Ismail Mohamed
- Department of Pediatrics; IWK Health Center; Dalhousie University; Halifax Nova Scotia Canada
| | - Harvey B. Sarnat
- Department of Pediatrics, Pathology, (Neuropathology) and Clinical Neurosciences; University of Calgary Faculty of Medicine; Alberta Children's Hospital; Calgary Alberta Canada
| | - Mitsuhiro Kato
- Department of Pediatrics; Yamagata University Faculty of Medicine; Yamagata Japan
| | | | - Hirotomo Saitsu
- Department of Human Genetics; Yokohama City University Graduate School of Medicine; Yokohama Japan
| | - Naomichi Matsumoto
- Department of Human Genetics; Yokohama City University Graduate School of Medicine; Yokohama Japan
| | - Masayuki Itoh
- Department of Mental Retardation and Birth Defect Research; National Institute of Neuroscience; National Center of Neurology and Psychiatry; Tokyo Japan
| | - Renate M. Kalnins
- Department of Anatomical Pathology; Austin Hospital; Melbourne Victoria Australia
- Department of Pathology; University of Melbourne; Melbourne Victoria Australia
| | - Chung W. Chow
- Department of Pediatrics; University of Melbourne; Melbourne Victoria Australia
- Department of Anatomical Pathology; Royal Children's Hospital; Melbourne Victoria Australia
| | - A. Simon Harvey
- Department of Neurology; Royal Children's Hospital; Melbourne Victoria Australia
- Murdoch Childrens Research Institute; Melbourne Victoria Australia
- Department of Pediatrics; University of Melbourne; Melbourne Victoria Australia
| | - Graeme D. Jackson
- Epilepsy Research Centre; University of Melbourne; Austin Health; Melbourne Victoria Australia
- Department of Radiology; University of Melbourne; Melbourne Victoria Australia
| | - Peter B. Crino
- Shriners Hospitals Pediatric Research Center; Temple University; Philadelphia Pennsylvania U.S.A
| | - Samuel F. Berkovic
- Epilepsy Research Centre; University of Melbourne; Austin Health; Melbourne Victoria Australia
| | - Ingrid E. Scheffer
- Department of Neurology; Royal Children's Hospital; Melbourne Victoria Australia
- Department of Pediatrics; University of Melbourne; Melbourne Victoria Australia
- Epilepsy Research Centre; University of Melbourne; Austin Health; Melbourne Victoria Australia
- Department of Radiology; University of Melbourne; Melbourne Victoria Australia
| |
Collapse
|
41
|
Wong M. A critical review of mTOR inhibitors and epilepsy: from basic science to clinical trials. Expert Rev Neurother 2014; 13:657-69. [PMID: 23739003 DOI: 10.1586/ern.13.48] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Present medications for epilepsy have substantial limitations, such as medical intractability in many patients and lack of antiepileptogenic properties to prevent epilepsy. Drugs with novel mechanisms of action are needed to overcome these limitations. The mTOR signaling pathway has emerged as a possible therapeutic target for epilepsy. Preliminary clinical trials suggest that mTOR inhibitors reduce seizures in tuberous sclerosis complex (TSC) patients with intractable epilepsy. Furthermore, mTOR inhibitors have antiepileptogenic properties in preventing epilepsy in animal models of TSC. Besides TSC, accumulating preclinical data suggest that mTOR inhibitors may have antiseizure or antiepileptogenic actions in other types of epilepsy, including infantile spasms, neonatal hypoxic seizures, absence epilepsy and acquired temporal lobe epilepsy following brain injury, but these effects depend on a number of conditions. Future clinical and basic research is needed to establish whether mTOR inhibitors are an effective treatment for epilepsy.
Collapse
Affiliation(s)
- Michael Wong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA.
| |
Collapse
|
42
|
Jia L, Liang T, Yu X, Ma C, Zhang S. MGARP regulates mouse neocortical development via mitochondrial positioning. Mol Neurobiol 2013; 49:1293-308. [PMID: 24323429 DOI: 10.1007/s12035-013-8602-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/26/2013] [Indexed: 12/20/2022]
Abstract
Neocortical development is an extremely complicated process that critically depends on the proper migration, distribution, and positioning of neural cells. Here, we identified mitochondria-localized glutamic acid-rich protein (MGARP) as a negative regulator of neocortical development. In the developing neocortex, the overexpression of MGARP by in utero electroporation impedes the radial migration of neocortical cells to their final destination. These neocortical cells failed to be normally polarized, leading to shortened axons and compromised axonal bundles. The number of dendrites was also attenuated in cells with MGARP overexpression and was expanded in MGARP-knockdown or knockout cells. Mechanistic studies indicated that overexpression of MGARP caused alterations in the structural integrity, subcellular distribution, and motility of mitochondria. The mitochondria in MGARP-overexpressing cells became "fatty" with a round morphology, and the total number of mitochondria in MGARP-overexpressing cells was also decreased in the cell body and dendrites as well as in the axons. Time lapse studies showed that the ratio of motile mitochondria was remarkably decreased in the axons of MGARP-overexpressing cells. Together, our findings suggest that MGARP negatively mediates neocortical development by regulating mitochondrial distribution and motility in neocortical neurons.
Collapse
Affiliation(s)
- Liyun Jia
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | | | | | | | | |
Collapse
|
43
|
Yang K, Su J, Hu Z, Lang R, Sun X, Li X, Wang D, Wei M, Yin J. Triple pathology in patients with temporal lobe epilepsy: A case report and review of the literature. Exp Ther Med 2013; 6:925-928. [PMID: 24137291 PMCID: PMC3797311 DOI: 10.3892/etm.2013.1228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 07/01/2013] [Indexed: 11/23/2022] Open
Abstract
The coexistence of three intracranial lesions related to epileptic pathogenesis is known as ‘triple pathology’ and has rarely been reported. In this study we report a case of temporal lobe epilepsy (TLE) with the coexistence of hippocampal sclerosis (HS), focal cortical dysplasia (FCD) and ganglioglioma in the temporal lobe. A 29-year-old male who had experienced recurrent seizures for four years was admitted to hospital. Cerebral magnetic resonance imaging (MRI) was conducted and T2-weighted and fluid-attenuated inversion recovery sequence (FLAIR) images revealed a reduced hippocampal volume with an increased FLAIR signal on the right side and a slightly enlarged temporal horn, which are typical imaging findings for HS and FCD. The patient underwent resectioning of the right anterior temporal lobe, hippocampus and amygdala, in addition to the lesion located in the medial temporal lobe. Immunohistochemical analysis of the medial temporal lobe lesion confirmed a ganglioglioma (WHO grade I) in the medial temporal lobe. During the first eight months following surgery, the patient's seizures were controlled with zonisamide and phenytoin. Electroencephalogram (EEG) assessment post-surgery confirmed the absence of epileptic discharges. Based on a literature review and a detailed review of this case, we postulate two possible explanations for the pathogenesis of ‘triple pathology’: i) ‘triple pathology’ is a combination of pathological progression and occasionality; and ii) ‘triple pathology’ lesions have similar pathological origins.
Collapse
Affiliation(s)
- Kang Yang
- Department of Neurosurgery, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning 116044, P.R. China
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Galanopoulou AS. Basic mechanisms of catastrophic epilepsy -- overview from animal models. Brain Dev 2013; 35:748-56. [PMID: 23312951 PMCID: PMC3644363 DOI: 10.1016/j.braindev.2012.12.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 12/09/2012] [Accepted: 12/10/2012] [Indexed: 12/14/2022]
Abstract
Infantile spasms are age-specific seizures of infantile epileptic encephalopathies that are usually associated with poor epilepsy and neurodevelopmental outcomes. The current treatments are not always effective and may be associated with significant side effects. Various mechanisms have been proposed as pathogenic for infantile spasms, including cortical or brainstem dysfunction, disruption of normal cortical-subcortical communications, genetic defects, inflammation, stress, developmental abnormalities. Many of these have been recently tested experimentally, resulting into the emergence of several animal models of infantile spasms. The stress theory of spasms yielded the corticotropin releasing hormone (CRH)-induced model, which showed the higher proconvulsant potency of CRH in developing rats, although only limbic seizures were observed. Models of acute induction of infantile spasms in rodents include the N-methyl-d-aspartate (NMDA) model of emprosthotonic seizures, the prenatal betamethasone and prenatal stress variants of the NMDA model, and the γ-butyrolactone induced spasms in a Down's syndrome mouse model. Chronic rodent models of infantile spasms include the tetrodotoxin model and the multiple-hit models in rats, as well as two genetic mouse models of interneuronopathies with infantile spasms due to loss of function of the aristaless X-linked homeobox-related gene (ARX). This review discusses the emerging mechanisms for generation of infantile spasms and their associated chronic epileptic and dyscognitive phenotype as well as the recent progress in identifying pathways to better treat this epileptic encephalopathy.
Collapse
|
45
|
Gipson TT, Gerner G, Wilson MA, Blue ME, Johnston MV. Potential for treatment of severe autism in tuberous sclerosis complex. World J Clin Pediatr 2013; 2:16-25. [PMID: 25254170 PMCID: PMC4145642 DOI: 10.5409/wjcp.v2.i3.16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/30/2013] [Accepted: 06/04/2013] [Indexed: 02/06/2023] Open
Abstract
The Food and Drug Administration (FDA) has approved two mechanism-based treatments for tuberous sclerosis complex (TSC)-everolimus and vigabatrin. However, these treatments have not been systematically studied in individuals with TSC and severe autism. The aim of this review is to identify the clinical features of severe autism in TSC, applicable preclinical models, and potential barriers that may warrant strategic planning in the design phase of clinical trial development. A comprehensive search strategy was formed and searched across PubMed, Embase and SCOPUS from their inception to 2/21/12, 3/16/12, and 3/12/12 respectively. After the final search date, relevant, updated articles were selected from PubMed abstracts generated electronically and emailed daily from PubMed. The references of selected articles were searched, and relevant articles were selected. A search of clinicaltrials.gov was completed using the search term “TSC” and “tuberous sclerosis complex”. Autism has been reported in as many as 60% of individuals with TSC; however, review of the literature revealed few data to support clear classification of the severity of autism in TSC. Variability was identified in the diagnostic approach, assessment of cognition, and functional outcome among the reviewed studies and case reports. Objective outcome measures were not used in many early studies; however, diffusion tensor imaging of white matter, neurophysiologic variability in infantile spasms, and cortical tuber subcategories were examined in recent studies and may be useful for objective classification of TSC in future studies. Mechanism-based treatments for TSC are currently available. However, this literature review revealed two potential barriers to successful design and implementation of clinical trials in individuals with severe autism-an unclear definition of the population and lack of validated outcome measures. Recent studies of objective outcome measures in TSC and further study of applicable preclinical models present an opportunity to overcome these barriers.
Collapse
|
46
|
Meng XF, Yu JT, Song JH, Chi S, Tan L. Role of the mTOR signaling pathway in epilepsy. J Neurol Sci 2013; 332:4-15. [PMID: 23773767 DOI: 10.1016/j.jns.2013.05.029] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/19/2013] [Accepted: 05/23/2013] [Indexed: 11/19/2022]
Abstract
Epilepsy, a common neurological disorder and cause of significant morbidity and mortality, places an enormous burden on the individual and society. Presently, most drugs for epilepsy primarily suppress seizures as symptomatic therapies but do not possess actual antiepileptogenic or disease-modifying properties. The mTOR (mammalian target of rapamycin) signaling pathway is involved in major multiple cellular functions, including protein synthesis, cell growth and proliferation and synaptic plasticity, which may influence neuronal excitability and be responsible for epileptogenesis. Intriguing findings of the frequent hyperactivation of mTOR signaling in epilepsy make it a potential mechanism in the pathogenesis as well as an attractive target for the therapeutic intervention, and have driven the significant ongoing efforts to pharmacologically target this pathway. This review explores the relevance of the mTOR pathway to epileptogenesis and its potential as a therapeutic target in epilepsy treatment by presenting the current results on mTOR inhibitors, in particular, rapamycin, in animal models of diverse types of epilepsy. Limited clinical studies in human epilepsy, some paradoxical experimental data and outstanding questions have also been discussed.
Collapse
Affiliation(s)
- Xiang-Fei Meng
- Department of Neurology, School of Medicine, Qingdao Municipal Hospital, Qingdao University, China
| | | | | | | | | |
Collapse
|
47
|
Abstract
Epilepsy is a prevalent neurological disorder associated with significant morbidity and mortality, but the only available drug therapies target its symptoms rather than the underlying cause. The process that links brain injury or other predisposing factors to the subsequent emergence of epilepsy is termed epileptogenesis. Substantial research has focused on elucidating the mechanisms of epileptogenesis so as to identify more specific targets for intervention, with the hope of preventing epilepsy before seizures emerge. Recent work has yielded important conceptual advances in this field. We suggest that such insights into the mechanisms of epileptogenesis converge at the level of cortical circuit dysfunction.
Collapse
|
48
|
Palmini A, Holthausen H. Focal malformations of cortical development: a most relevant etiology of epilepsy in children. HANDBOOK OF CLINICAL NEUROLOGY 2013; 111:549-565. [PMID: 23622203 DOI: 10.1016/b978-0-444-52891-9.00058-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Malformations of cortical development (MCD) are now well established as a most prevalent and relevant etiology of medically refractory epilepsies in children and adolescents. Focal cortical dysplasia (FCD) and hemimegalencephalies (HMG) occupy a special status because their focality (or in the case of HMG, their unihemispheric distibution) makes them amenable to surgical treatment to attempt seizure control. Since interictal epileptiform discharges and frequent seizures can lead to abnormal development because of brain plasticity during early childhood, the aim of surgical treatment is not only seizure control but also the redirection of development toward more physiological paths. In this review, we propose an "imaging-semiological organization" including (1) patients whose dysplastic lesion surrounds the fronto-rolandic cortex with increased signal and a transmantle sign, (2) multilobar hemispheric lesions, predominating in the anterior or posterior quadrants with large areas of abnormal gyration, increased cortical thickness, and gray-white blurring, (3) anterior temporal dysplasias usually featuring volume reduction combined with blurring of the underlying white matter in the temporal pole, and (4) a very relevant group of patients with refractory seizures, normal or roughly normal intellect, and normal MRI, later shown to harbor microscopic "nidus" of dysplastic cells. Classification takes into account the cortical disorganization, the presence of aberrant cellular elements, and the association with other lesion types.
Collapse
Affiliation(s)
- André Palmini
- Neurology Service and Epilepsy Surgery Program, Hospital São Lucas; Faculty of Medicine, Pontificia Universidade Católica do Rio Grande do Sul and Brain Institute of Rio Grande do Sul, Porto Alegre, Brazil.
| | | |
Collapse
|
49
|
Sarnat HB, Flores-Sarnat L. Genetics of neural crest and neurocutaneous syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2013; 111:309-14. [PMID: 23622181 DOI: 10.1016/b978-0-444-52891-9.00036-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Neural crest progenitor cells are identified at the lateral margins of the neural placode at the time of gastrulation. With folding of the placode, these precursors are brought to the dorsal midline of the neural tube at the site of closure, become committed to neural crest lineage and almost immediately migrate peripherally to various predetermined sites in the body and then differentiate as a variety of cellular types in all three of the traditional "germ layers." All of these processes of migration and differentiation of neural crest are precisely genetically programed, temporally and spatially, by a variety of genes. Primary neurocutaneous syndromes are all very different diseases with different genetic mutations, but the unifying factor amongst them is that all are neurocristopathies and can be explained as such, including the tumor-suppressor function of several of these genes, especially those of neurofibromatosis 1 and 2 and tuberous sclerosis. This chapter reviews the principal genes that program neural crest development and also are documented, implicated, or suspected in the pathogenesis of neurocutaneous syndromes. Recent genetic discoveries are noted in epidermal nevus syndrome, including Proteus syndrome and their association with hemimegalencephaly and congenital infiltrating lipomatosis of the face.
Collapse
Affiliation(s)
- Harvey B Sarnat
- Departments of Clinical Neurosciences and Paediatrics, Division of Paediatric Neurology, University of Calgary, Alberta Children's Hospital, Calgary, Canada
| | | |
Collapse
|
50
|
Abstract
Structural abnormalities of the brain are increasingly recognized in patients that suffer from pharmacoresistant focal epilepsies by applying high-resolution imaging techniques. In many of these patients, epilepsy surgery results in control of seizures. Neuropathologically, a broad spectrum of malformations of cortical development (MCD) is observed in respective surgical brain samples. These samples provide a unique basis to further understand underlying pathomechanisms by molecular approaches and develop improved diagnostics and entirely new therapeutic perspectives. Here we provide a comprehensive description of neuropathological findings, available classification systems as well as molecular mechanisms of MCDs. We emphasize the recently published ILEA classification system for focal cortical dysplasias (FCDs), which are now histopathologically distinguished as types I to III. However, this revised classification system represents a major challenge for molecular neuropathologists, as the underlying pathomechanisms in virtually all FCD entities will need to be specified in detail. The fact that only recently, the mammalian target of rapamycin (mTOR)-antagonist Everolimus has been introduced as a treatment of epilepsies in the context of tuberous sclerosis-associated brain lesions is a striking example of a successful translational "bedside to bench and back" approach. Hopefully, the exciting clinico-pathological developments in the field of MCDs will in short term foster further therapeutic breakthroughs for the frequently associated medically refractory epilepsies.
Collapse
Affiliation(s)
- Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Amsterdam
| | | | | |
Collapse
|