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Ma Q, Chen G, Li Y, Guo Z, Zhang X. The molecular genetics of PI3K/PTEN/AKT/mTOR pathway in the malformations of cortical development. Genes Dis 2024; 11:101021. [PMID: 39006182 PMCID: PMC11245990 DOI: 10.1016/j.gendis.2023.04.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 04/07/2023] [Accepted: 04/30/2023] [Indexed: 07/16/2024] Open
Abstract
Malformations of cortical development (MCD) are a group of developmental disorders characterized by abnormal cortical structures caused by genetic or harmful environmental factors. Many kinds of MCD are caused by genetic variation. MCD is the common cause of intellectual disability and intractable epilepsy. With rapid advances in imaging and sequencing technologies, the diagnostic rate of MCD has been increasing, and many potential genes causing MCD have been successively identified. However, the high genetic heterogeneity of MCD makes it challenging to understand the molecular pathogenesis of MCD and to identify effective targeted drugs. Thus, in this review, we outline important events of cortical development. Then we illustrate the progress of molecular genetic studies about MCD focusing on the PI3K/PTEN/AKT/mTOR pathway. Finally, we briefly discuss the diagnostic methods, disease models, and therapeutic strategies for MCD. The information will facilitate further research on MCD. Understanding the role of the PI3K/PTEN/AKT/mTOR pathway in MCD could lead to a novel strategy for treating MCD-related diseases.
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Affiliation(s)
- Qing Ma
- NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, Heilongjiang 150000, China
| | - Guang Chen
- Department of Urology, The Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang 150000, China
| | - Ying Li
- NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, Heilongjiang 150000, China
- Department of Child and Adolescent Health, School of Public Health, Harbin Medical University, Harbin, Heilongjiang 150000, China
| | - Zhenming Guo
- Institute for Regenerative Medicine, Shanghai East Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai 200120, China
| | - Xue Zhang
- NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics, Harbin Medical University, Harbin, Heilongjiang 150000, China
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2
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Lee HM, Hong SJ, Gill R, Caldairou B, Wang I, Zhang JG, Deleo F, Schrader D, Bartolomei F, Guye M, Cho KH, Barba C, Sisodiya S, Jackson G, Hogan RE, Wong-Kisiel L, Cascino GD, Schulze-Bonhage A, Lopes-Cendes I, Cendes F, Guerrini R, Bernhardt B, Bernasconi N, Bernasconi A. Multimodal mapping of regional brain vulnerability to focal cortical dysplasia. Brain 2023; 146:3404-3415. [PMID: 36852571 PMCID: PMC10393418 DOI: 10.1093/brain/awad060] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/17/2023] [Accepted: 02/02/2023] [Indexed: 03/01/2023] Open
Abstract
Focal cortical dysplasia (FCD) type II is a highly epileptogenic developmental malformation and a common cause of surgically treated drug-resistant epilepsy. While clinical observations suggest frequent occurrence in the frontal lobe, mechanisms for such propensity remain unexplored. Here, we hypothesized that cortex-wide spatial associations of FCD distribution with cortical cytoarchitecture, gene expression and organizational axes may offer complementary insights into processes that predispose given cortical regions to harbour FCD. We mapped the cortex-wide MRI distribution of FCDs in 337 patients collected from 13 sites worldwide. We then determined its associations with (i) cytoarchitectural features using histological atlases by Von Economo and Koskinas and BigBrain; (ii) whole-brain gene expression and spatiotemporal dynamics from prenatal to adulthood stages using the Allen Human Brain Atlas and PsychENCODE BrainSpan; and (iii) macroscale developmental axes of cortical organization. FCD lesions were preferentially located in the prefrontal and fronto-limbic cortices typified by low neuron density, large soma and thick grey matter. Transcriptomic associations with FCD distribution uncovered a prenatal component related to neuroglial proliferation and differentiation, likely accounting for the dysplastic makeup, and a postnatal component related to synaptogenesis and circuit organization, possibly contributing to circuit-level hyperexcitability. FCD distribution showed a strong association with the anterior region of the antero-posterior axis derived from heritability analysis of interregional structural covariance of cortical thickness, but not with structural and functional hierarchical axes. Reliability of all results was confirmed through resampling techniques. Multimodal associations with cytoarchitecture, gene expression and axes of cortical organization indicate that prenatal neurogenesis and postnatal synaptogenesis may be key points of developmental vulnerability of the frontal lobe to FCD. Concordant with a causal role of atypical neuroglial proliferation and growth, our results indicate that FCD-vulnerable cortices display properties indicative of earlier termination of neurogenesis and initiation of cell growth. They also suggest a potential contribution of aberrant postnatal synaptogenesis and circuit development to FCD epileptogenicity.
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Affiliation(s)
- Hyo M Lee
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Seok-Jun Hong
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Montreal, Canada
- Center for Neuroscience Imaging, Research Institute for Basic Science, Department of Global Biomedical Engineering, SungKyunKwan University, Suwon, KoreaSuwon, Korea
| | - Ravnoor Gill
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Benoit Caldairou
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Irene Wang
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Jian-guo Zhang
- Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Francesco Deleo
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico C. Besta, Milano, Italy
| | - Dewi Schrader
- Department of Pediatrics, British Columbia Children’s Hospital, Vancouver, Canada
| | - Fabrice Bartolomei
- Aix Marseille Univ, INSERM, INS, Institut de Neurosciences des Systèmes, Marseille, 13005, France
| | - Maxime Guye
- Aix Marseille University, CNRS, CRMBM UMR 7339, Marseille, France
| | - Kyoo Ho Cho
- Department of Neurology, Yonsei University College of Medicine, Seoul, Korea
| | - Carmen Barba
- Meyer Children's Hospital IRCCS, Florence, Italy
- University of Florence, 50121 Florence, Italy
| | - Sanjay Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
| | - Graeme Jackson
- The Florey Institute of Neuroscience and Mental Health and The University of Melbourne, Victoria, Australia
| | - R Edward Hogan
- Department of Neurology, Washington University School of Medicine, St Louis, MO, USA
| | | | | | | | - Iscia Lopes-Cendes
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP) and the Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas SP, Brazil
| | - Fernando Cendes
- Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), and the Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas SP, Brazil
| | - Renzo Guerrini
- Meyer Children's Hospital IRCCS, Florence, Italy
- University of Florence, 50121 Florence, Italy
| | - Boris Bernhardt
- Multimodal Imaging and Connectome Analysis Lab, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Montreal, Canada
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3
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Focal cortical dysplasia as a cause of epilepsy: The current evidence of associated genes and future therapeutic treatments. INTERDISCIPLINARY NEUROSURGERY 2022. [DOI: 10.1016/j.inat.2022.101635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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4
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Ko A, Sim NS, Choi HS, Yang D, Kim SH, Lee JS, Kim DS, Lee JH, Kim HD, Kang HC. Efficacy of the Ketogenic Diet for Pediatric Epilepsy According to the Presence of Detectable Somatic mTOR Pathway Mutations in the Brain. J Clin Neurol 2022; 18:71-78. [PMID: 35021279 PMCID: PMC8762511 DOI: 10.3988/jcn.2022.18.1.71] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 11/23/2022] Open
Abstract
Background and Purpose A multifactorial antiepileptic mechanism underlies the ketogenic diet (KD), and one of the proposed mechanisms of action is that the KD inhibits the mammalian target of rapamycin (mTOR) pathway. To test this clinically, this study aimed to determine the efficacy of the KD in patients with pathologically confirmed focal cortical dysplasia (FCD) due to genetically identifiable mTOR pathway dysregulation. Methods A cohort of patients with pathologically confirmed FCD after epilepsy surgery and who were screened for the presence of germline and somatic mutations related to the mTOR pathway in peripheral blood and resected brain tissue was constructed prospectively. A retrospective review of the efficacy of the prior KD in these patients was performed. Results Twenty-five patients with pathologically confirmed FCD and who were screened for the presence of detectable somatic mTOR pathway mutations had received a sufficient KD. Twelve of these patients (48.0%) had germline or somatic detectable mTOR pathway mutations. A response was defined as a ≥50% reduction in seizure frequency. The efficacy of the KD after 3 months of dietary therapy was superior in patients with detectable mTOR pathway mutations than in patients without detectable mTOR pathway mutations, although the difference was not statistically significant (responder rates of 58.3% vs. 38.5%, p=0.434). Conclusions A greater proportion of patients with mTOR pathway responded to the KD, but there was no statistically significant difference in efficacy of the KD between patients with and without detectable mTOR pathway mutations. Further study is warranted due to the smallness of the sample and the limited number of mTOR pathway genes tested in this study.
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Affiliation(s)
- Ara Ko
- Department of Pediatrics, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Nam Suk Sim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Han Som Choi
- Department of Pediatrics, Ewha Womans University Seoul Hospital, Ewha Womans University School of Medicine, Seoul, Korea.,Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Donghwa Yang
- Department of Pediatrics, National Health Insurance Service Ilsan Hospital, Goyang, Korea
| | - Se Hee Kim
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Joon Soo Lee
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Dong Seok Kim
- Department of Neurosurgery, Pediatric Neurosurgery, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Jeong Ho Lee
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Heung Dong Kim
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea.
| | - Hoon-Chul Kang
- Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea.
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5
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D'Gama AM, Poduri A. Precision Therapy for Epilepsy Related to Brain Malformations. Neurotherapeutics 2021; 18:1548-1563. [PMID: 34608615 PMCID: PMC8608994 DOI: 10.1007/s13311-021-01122-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2021] [Indexed: 02/04/2023] Open
Abstract
Malformations of cortical development (MCDs) represent a range of neurodevelopmental disorders that are collectively common causes of developmental delay and epilepsy, especially refractory childhood epilepsy. Initial treatment with antiseizure medications is empiric, and consideration of surgery is the standard of care for eligible patients with medically refractory epilepsy. In the past decade, advances in next generation sequencing technologies have accelerated progress in understanding the genetic etiologies of MCDs, and precision therapies for focal MCDs are emerging. Notably, mutations that lead to abnormal activation of the mammalian target of rapamycin (mTOR) pathway, which provides critical control of cell growth and proliferation, have emerged as a common cause of malformations. These include tuberous sclerosis complex (TSC), hemimegalencephaly (HME), and some types of focal cortical dysplasia (FCD). TSC currently represents the best example for the pathway from gene discovery to relatively safe and efficacious targeted therapy for epilepsy related to MCDs. Based on extensive pre-clinical and clinical data, the mTOR inhibitor everolimus is currently approved for the treatment of focal refractory seizures in patients with TSC. Although clinical studies are just emerging for FCD and HME, we believe the next decade will bring significant advancements in precision therapies for epilepsy related to these and other MCDs.
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Affiliation(s)
- Alissa M D'Gama
- Divisions of Newborn Medicine and Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
- Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA.
- Broad Institute of Harvard and MIT, Cambridge, MA, USA.
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6
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Koboldt DC, Miller KE, Miller AR, Bush JM, McGrath S, Leraas K, Crist E, Fair S, Schwind W, Wijeratne S, Fitch J, Leonard J, Shaikhouni A, Hester ME, Magrini V, Ho ML, Pierson CR, Wilson RK, Ostendorf AP, Mardis ER, Bedrosian TA. PTEN somatic mutations contribute to spectrum of cerebral overgrowth. Brain 2021; 144:2971-2978. [PMID: 34048549 DOI: 10.1093/brain/awab173] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/26/2021] [Accepted: 04/13/2021] [Indexed: 11/12/2022] Open
Abstract
Phosphatase and tensin homolog (PTEN) regulates cell growth and survival through inhibition of the mammalian target of rapamycin (MTOR) signaling pathway. Germline genetic variation of PTEN is associated with autism, macrocephaly, and PTEN hamartoma tumor syndromes (PHTS). The effect of developmental PTEN somatic mutations on nervous system phenotypes is not well understood, although brain somatic mosaicism of MTOR pathway genes is an emerging cause of cortical dysplasia and epilepsy in the pediatric population. Here we report two somatic variants of PTEN affecting a single patient presenting with intractable epilepsy and hemimegalencephaly that varied in clinical severity throughout the left cerebral hemisphere. High-throughput sequencing analysis of affected brain tissue identified two somatic variants in PTEN. The first variant was present in multiple cell lineages throughout the entire hemisphere and associated with mild cerebral overgrowth. The second variant was restricted to posterior brain regions and affected the opposite PTEN allele, resulting in a segmental region of more severe malformation, and the only neurons in which it was found by single-nuclei RNA-seq had a unique disease-related expression profile. This study reveals brain mosaicism of PTEN as a disease mechanism of hemimegalencephaly and furthermore demonstrates the varying effects of single- or bi-allelic disruption of PTEN on cortical phenotypes.
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Affiliation(s)
- Daniel C Koboldt
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Katherine E Miller
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Anthony R Miller
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Jocelyn M Bush
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Sean McGrath
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Kristen Leraas
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Erin Crist
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Division of Genetic and Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Summer Fair
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Wesley Schwind
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Saranga Wijeratne
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - James Fitch
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Jeffrey Leonard
- Department of Neurosurgery, Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Neurosurgery, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Ammar Shaikhouni
- Department of Neurosurgery, Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Neurosurgery, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Mark E Hester
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Vincent Magrini
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Mai-Lan Ho
- Department of Radiology, Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Christopher R Pierson
- Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pathology, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Biomedical Education and Anatomy, Division of Anatomy, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Richard K Wilson
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Adam P Ostendorf
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Neurosurgery, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Division of Child Neurology, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Elaine R Mardis
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA.,Department of Neurosurgery, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Tracy A Bedrosian
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
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7
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Jesus-Ribeiro J, Pires LM, Melo JD, Ribeiro IP, Rebelo O, Sales F, Freire A, Melo JB. Genomic and Epigenetic Advances in Focal Cortical Dysplasia Types I and II: A Scoping Review. Front Neurosci 2021; 14:580357. [PMID: 33551717 PMCID: PMC7862327 DOI: 10.3389/fnins.2020.580357] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 12/14/2020] [Indexed: 12/19/2022] Open
Abstract
Introduction: Focal cortical dysplasias (FCDs) are a group of malformations of cortical development that constitute a common cause of drug-resistant epilepsy, often subjected to neurosurgery, with a suboptimal long-term outcome. The past few years have witnessed a dramatic leap in our understanding of the molecular basis of FCD. This study aimed to provide an updated review on the genomic and epigenetic advances underlying FCD etiology, to understand a genotype-phenotype correlation and identify priorities to lead future translational research. Methods: A scoping review of the literature was conducted, according to previously described methods. A comprehensive search strategy was applied in PubMed, Embase, and Web of Science from inception to 07 May 2020. References were screened based on title and abstract, and posteriorly full-text articles were assessed for inclusion according to eligibility criteria. Studies with novel gene variants or epigenetic regulatory mechanisms in patients that underwent epilepsy surgery, with histopathological diagnosis of FCD type I or II according to Palmini's or the ILAE classification system, were included. Data were extracted and summarized for an overview of evidence. Results: Of 1,156 candidate papers, 39 met the study criteria and were included in this review. The advent of next-generation sequencing enabled the detection in resected FCD tissue of low-level brain somatic mutations that occurred during embryonic corticogenesis. The mammalian target of rapamycin (mTOR) signaling pathway, involved in neuronal growth and migration, is the key player in the pathogenesis of FCD II. Somatic gain-of-function variants in MTOR and its activators as well as germline, somatic, and second-hit mosaic loss-of-function variants in its related repressors have been reported. However, the genetic background of FCD type I remains elusive, with a pleomorphic repertoire of genes affected. DNA methylation and microRNAs were the two epigenetic mechanisms that proved to have a functional role in FCD and may represent molecular biomarkers. Conclusion: Further research into the possible pathogenic causes of both FCD subtypes is required, incorporating single-cell DNA/RNA sequencing as well as methylome and proteomic analysis. The collected data call for an integrated clinicopathologic and molecular genetic diagnosis in current practice not only to improve diagnostic accuracy but also to guide the development of future targeted treatments.
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Affiliation(s)
- Joana Jesus-Ribeiro
- Epilepsy and Sleep Monitoring Unit, Neurology Department, Coimbra University Hospital Center, Coimbra, Portugal.,iCBR/CIMAGO, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Luís Miguel Pires
- iCBR/CIMAGO, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,Laboratory of Cytogenetics and Genomics, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | | | - Ilda Patrícia Ribeiro
- iCBR/CIMAGO, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,Laboratory of Cytogenetics and Genomics, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Olinda Rebelo
- Neuropathology Laboratory, Neurology Department, Coimbra University Hospital Center, Coimbra, Portugal
| | - Francisco Sales
- Epilepsy and Sleep Monitoring Unit, Neurology Department, Coimbra University Hospital Center, Coimbra, Portugal
| | - António Freire
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Joana Barbosa Melo
- iCBR/CIMAGO, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,Laboratory of Cytogenetics and Genomics, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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8
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An N, Bassil K, Al Jowf GI, Steinbusch HWM, Rothermel M, de Nijs L, Rutten BPF. Dual-specificity phosphatases in mental and neurological disorders. Prog Neurobiol 2020; 198:101906. [PMID: 32905807 DOI: 10.1016/j.pneurobio.2020.101906] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 08/26/2020] [Accepted: 09/01/2020] [Indexed: 01/01/2023]
Abstract
The dual-specificity phosphatase (DUSP) family includes a heterogeneous group of protein phosphatases that dephosphorylate both phospho-tyrosine and phospho-serine/phospho-threonine residues within a single substrate. These protein phosphatases have many substrates and modulate diverse neural functions, such as neurogenesis, differentiation, and apoptosis. DUSP genes have furthermore been associated with mental disorders such as depression and neurological disorders such as Alzheimer's disease. Herein, we review the current literature on the DUSP family of genes concerning mental and neurological disorders. This review i) outlines the structure and general functions of DUSP genes, and ii) overviews the literature on DUSP genes concerning mental and neurological disorders, including model systems, while furthermore providing perspectives for future research.
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Affiliation(s)
- Ning An
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands; European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Katherine Bassil
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands; European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Ghazi I Al Jowf
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands; College of Applied Medical Sciences, Department of Public Health, King Faisal University, Al-Ahsa, Saudi Arabia; European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Harry W M Steinbusch
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands; European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Markus Rothermel
- European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands; Department of Chemosensation - AG Neuromodulation, RWTH Aachen University, Aachen, Germany
| | - Laurence de Nijs
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands; European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Bart P F Rutten
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands; European Graduate School of Neuroscience, Maastricht University, Maastricht, the Netherlands.
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9
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White AR, Tiwari D, MacLeod MC, Danzer SC, Gross C. PI3K isoform-selective inhibition in neuron-specific PTEN-deficient mice rescues molecular defects and reduces epilepsy-associated phenotypes. Neurobiol Dis 2020; 144:105026. [PMID: 32712265 DOI: 10.1016/j.nbd.2020.105026] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/13/2020] [Accepted: 07/20/2020] [Indexed: 01/16/2023] Open
Abstract
Epilepsy affects all ages, races, genders, and socioeconomic groups. In about one third of patients, epilepsy is uncontrolled with current medications, leaving a vast need for improved therapies. The causes of epilepsy are diverse and not always known but one gene mutated in a small subpopulation of patients is phosphatase and tensin homolog (PTEN). Moreover, focal cortical dysplasia, which constitutes a large fraction of refractory epilepsies, has been associated with signaling defects downstream of PTEN. So far, most preclinical attempts to reverse PTEN deficiency-associated neurological deficits have focused on mTOR, a signaling hub several steps downstream of PTEN. Phosphoinositide 3-kinases (PI3Ks), by contrast, are the direct enzymatic counteractors of PTEN, and thus may be alternative treatment targets. PI3K activity is mediated by four different PI3K catalytic isoforms. Studies in cancer, where PTEN is commonly mutated, have demonstrated that inhibition of only one isoform, p110β, reduces progression of PTEN-deficient tumors. Importantly, inhibition of a single PI3K isoform leaves critical functions of general PI3K signaling throughout the body intact. Here, we show that this disease mechanism-targeted strategy borrowed from cancer research rescues or ameliorates neuronal phenotypes in male and female mice with neuron-specific PTEN deficiency. These phenotypes include cell signaling defects, protein synthesis aberrations, seizures, and cortical dysplasia. Of note, p110β is also dysregulated and a promising treatment target in the intellectual disability Fragile X syndrome, pointing towards a shared biological mechanism that is therapeutically targetable in neurodevelopmental disorders of different etiologies. Overall, this work advocates for further assessment of p110β inhibition not only in PTEN deficiency-associated neurodevelopmental diseases but also other brain disorders characterized by defects in the PI3K/mTOR pathway.
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Affiliation(s)
- Angela R White
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Durgesh Tiwari
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, OH 45229, USA
| | - Molly C MacLeod
- Division of Neurology, 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 Anesthesiology, University of Cincinnati College of Medicine, OH 45229, USA
| | - Christina Gross
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, OH 45229, USA.
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10
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The Study of Genetic Susceptibility and Mitochondrial Dysfunction in Mesial Temporal Lobe Epilepsy. Mol Neurobiol 2020; 57:3920-3930. [PMID: 32632602 DOI: 10.1007/s12035-020-01993-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 06/22/2020] [Indexed: 10/23/2022]
Abstract
The aim of this study is to investigate the mitochondrial dysfunction and pathogenic role of the mitochondrial genome in the progression of mesial temporal lobe epilepsy (MTLE) in vivo and in vitro. Mitochondrial DNA (mtDNA) and nuclear DNA were detected in the hippocampal samples and peripheral blood of patients with MTLE. Mitochondrial functions were detected in vivo and in vitro. In 20 patients with MTLE, mtDNA mutations involving single or multiple deletions in the hippocampus were found in 5 patients but were not detected in the peripheral blood. Two patients carried pathogenic mutations of RELN, both in the hippocampus and blood. A pathogenic mutation of DNA2 was found in the hippocampus of the 2 patients with multiple deletions but not in the blood samples. The mtDNA copy numbers showed dynamic changes in the MTLE models. In MTLE patients, low metabolism in mesial temporal lobe and hippocampus was observed by using PET-CT. Under electron microscope, the mitochondrial cristae were disordered, the density of mitochondrial matrix decreased and even vacuolated in the hippocampus neurons. In the MTLE rat models, there were dynamic changes in mitochondrial morphology; the ATP production rate decreased in the acute phase, the latent phase, and the chronic phase. Mitochondrial enzyme complex I activity decreased in both acute and chronic phases, and there was no significant difference in latent period. Decreased mitochondrial membrane potential and calcium homeostasis were detected in the epileptic cell models. We first identified somatic mutations in mtDNA in MTLE patients and comprehensively evaluated mitochondrial dysfunction in the pathogenesis of MTLE in vivo and in vitro. This evidence supports the environmental and modifying genetic interactions that contribute to the development of MTLE.
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11
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Kumari K, Sharma MC, Kakkar A, Malgulwar PB, Pathak P, Suri V, Sarkar C, Chandra SP, Faruq M. mTOR pathway activation in focal cortical dysplasia. Ann Diagn Pathol 2020; 46:151523. [PMID: 32325422 DOI: 10.1016/j.anndiagpath.2020.151523] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 02/21/2020] [Accepted: 03/24/2020] [Indexed: 01/05/2023]
Abstract
BACKGROUND Focal cortical dysplasia (FCD) is a localized cortical malformation and considerable morphological overlap exists between FCD IIB and neurological lesions associated with Tuberous sclerosis complex (TSC). Abnormal mTOR pathway secondary to somatic mTOR mutation and TSC gene mutation linked to PI3K/AKT/mTOR pathway have supported the hypothesis of common pathogenesis involved. Role of converging pathway, viz. Wnt/β-Catenin and mTOR is unknown in FCD. We aimed to analyse FCD IIB for TSC1/TSC2 mutations, immunoreactivity of hamartin, tuberin, mTOR and Wnt signalling cascades, and stem cell markers. MATERIALS AND METHODS Sixteen FCD IIB cases were retrieved along with 16 FCD IIA cases for comparison. Immunohistochemistry was performed for tuberin, hamartin, mTOR pathway markers, markers of stem cell phenotype, and Wnt pathway markers. Mutation analysis for TSC1 and TSC2 was performed by sequencing in 9 FCD cases. RESULTS All FCD cases showed preserved hamartin and tuberin immunoreactivity. Aberrant immunoreactivity of phospho-P70S6 kinase, S6 ribosomal, phospho-S6 ribosomal and Stat3 was noted in FCD IIB, with variable phospho-4E-BP1 (45%) and absent phospho-Stat3 expression. Immunoreactivity for phospho-P70S6 kinase (100%), S6 ribosomal protein (100%) and Stat3 (100%) was noted in FCD IIA, but not for phospho-S6 ribosomal, phospho-4E-BP1 and phospho-Stat3. c-Myc immunoreactivity was noted in all FCD cases. Nestin (81%) and Sox 2 (88%) stained balloon cells in FCD IIB (44%), while in FCD IIA cases were negative. All FCD cases were immunopositive for Wnt, but were negative for β-Catenin and cyclin-D1. TSC mutations were detected in two cases of FCD IIB. CONCLUSION Abnormal mTOR pathway activation exists in FCD IIB and IIA, however, shows differential immunoreactivity profile, indicating varying degrees of dysregulation. Labelling of neuronal stem cell markers in balloon cells suggests they are phenotypically immature. TSC1/2 mutation play role in the pathogenesis of FCD. Deep targeted sequencing is preferred diagnostic technique since conventional sanger sequencing often fails to detect low-allele frequency variants involved in mTOR/TSC pathway genes, commonly found in FCD.
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Affiliation(s)
- Kalpana Kumari
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Mehar C Sharma
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
| | - Aanchal Kakkar
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Prit B Malgulwar
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Pankaj Pathak
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Vaishali Suri
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Chitra Sarkar
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Sarat P Chandra
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
| | - Mohammed Faruq
- Institute of Genomics and Integrative Biology - Council of Scientific and Industrial Research, New Delhi, India
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12
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Abstract
Epilepsy is a long-term neurological disease characterized by convulsions that can be recurrent. It is mainly caused by an imbalance between excitation and inhibition in the central nervous system. Currently, the pathogenesis is still unclear, although it may be related to changes in ion channels, neurotransmitters and glial cells. In recent years, increasing attention has been paid to the role of autophagy in the development of epilepsy. This chapter focuses on the role of the mTOR pathway in epileptogenesis and the relationship between autophagy, glycogen metabolism and Lafora disease and discusses the potential role of autophagy as a target for the treatment of epilepsy.
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Affiliation(s)
- Meihong Lv
- Institute of Neuroscience, Soochow University, Suzhou, Jiangsu Province, China
| | - Quanhong Ma
- Institute of Neuroscience, Soochow University, Suzhou, Jiangsu Province, China.
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13
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Zhao S, Li Z, Zhang M, Zhang L, Zheng H, Ning J, Wang Y, Wang F, Zhang X, Gan H, Wang Y, Zhang X, Luo H, Bu G, Xu H, Yao Y, Zhang YW. A brain somatic RHEB doublet mutation causes focal cortical dysplasia type II. Exp Mol Med 2019; 51:1-11. [PMID: 31337748 PMCID: PMC6802736 DOI: 10.1038/s12276-019-0277-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 03/27/2019] [Accepted: 04/10/2019] [Indexed: 01/16/2023] Open
Abstract
Focal cortical dysplasia type II (FCDII) is a cerebral cortex malformation characterized by local cortical structure disorganization, neuronal dysmorphology, and refractory epilepsy. Brain somatic mutations in several genes involved in the PI3K/AKT/mTOR pathway are associated with FCDII, but they are only found in a proportion of patients with FCDII. The genetic causes underlying the development FCDII in other patients remain unclear. Here, we carried out whole exome sequencing and targeted sequencing in paired brain–blood DNA from patients with FCDII and identified a brain somatic doublet mutation c.(A104T, C105A) in the Ras homolog, mTORC1 binding (RHEB) gene, which led to the RHEB p.Y35L mutation in one patient with FCDII. This RHEB mutation carrier had a dramatic increase of ribosomal protein S6 phosphorylation, indicating mTOR activation in the region of the brain lesion. The RHEB p.Y35L mutant protein had increased GTPλS-binding activity compared with wild-type RHEB. Overexpression of the RHEB p.Y35L variant in cultured cells also resulted in elevated S6 phosphorylation compared to wild-type RHEB. Importantly, in utero electroporation of the RHEB p.Y35L variant in mice induced S6 phosphorylation, cytomegalic neurons, dysregulated neuron migration, abnormal electroencephalogram, and seizures, all of which are found in patients with FCDII. Rapamycin treatment rescued abnormal electroencephalograms and alleviated seizures in these mice. These results demonstrate that brain somatic mutations in RHEB are also responsible for the pathogenesis of FCDII, indicating that aberrant activation of mTOR signaling is a primary driver and potential drug target for FCDII. Identifying a genetic mutation causing a congenital brain disorder that triggers difficult-to-treat epilepsy suggests a potential therapeutic target, according to Chinese scientists. Focal cortical dysplasia type II (FCDII) is one of a group of brain development abnormalities that cause intractable epilepsy. Scientists have identified gene mutations in some FCDII patients linked to a signaling pathway involved in cell proliferation and metabolism in the developing brain. Now, Yun-wu Zhang and Yi Yao at Xiamen University in Fujian, China, and co-workers have discovered a mutation on a gene which triggers abnormal activation of the same signaling pathway. The team found that the drug rapamycin, which inhibits this pathway, alleviated epileptic seizures in mice with the mutant gene. Their findings add weight to the theory that this pathway may be a viable target for future therapies.
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Affiliation(s)
- Shanshan Zhao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Zhenghui Li
- Neuromedicine Center, the 174th Hospital of Chinese People's Liberation Army, Affiliated Chenggong Hospital, Xiamen University, Xiamen, 361003, Fujian, China.,Department of Neurosurgery, Kaifeng Central Hospital, Kaifeng, 475000, Henan, China
| | - Muxian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Lingliang Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Honghua Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Jinhuan Ning
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Yanyan Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Fengpeng Wang
- Neuromedicine Center, the 174th Hospital of Chinese People's Liberation Army, Affiliated Chenggong Hospital, Xiamen University, Xiamen, 361003, Fujian, China.,XiaMen Humanity Hospital, No.3777 XianYue Road, HuLi District, XiaMen, 361015, FuJian, China
| | - Xiaobin Zhang
- Neuromedicine Center, the 174th Hospital of Chinese People's Liberation Army, Affiliated Chenggong Hospital, Xiamen University, Xiamen, 361003, Fujian, China.,XiaMen Humanity Hospital, No.3777 XianYue Road, HuLi District, XiaMen, 361015, FuJian, China
| | - Hexia Gan
- Neuromedicine Center, the 174th Hospital of Chinese People's Liberation Army, Affiliated Chenggong Hospital, Xiamen University, Xiamen, 361003, Fujian, China
| | - Yuanqing Wang
- Neuromedicine Center, the 174th Hospital of Chinese People's Liberation Army, Affiliated Chenggong Hospital, Xiamen University, Xiamen, 361003, Fujian, China
| | - Xian Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Hong Luo
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Huaxi Xu
- Neuroscience Initiative, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Yi Yao
- Neuromedicine Center, the 174th Hospital of Chinese People's Liberation Army, Affiliated Chenggong Hospital, Xiamen University, Xiamen, 361003, Fujian, China. .,XiaMen Humanity Hospital, No.3777 XianYue Road, HuLi District, XiaMen, 361015, FuJian, China. .,Department of Pediatric Neurology, Shenzhen Children's Hospital, Shenzhen, 518026, Guangdong Province, China.
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, 361102, Fujian, China.
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14
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Ye Z, McQuillan L, Poduri A, Green TE, Matsumoto N, Mefford HC, Scheffer IE, Berkovic SF, Hildebrand MS. Somatic mutation: The hidden genetics of brain malformations and focal epilepsies. Epilepsy Res 2019; 155:106161. [PMID: 31295639 DOI: 10.1016/j.eplepsyres.2019.106161] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/27/2019] [Accepted: 07/01/2019] [Indexed: 01/12/2023]
Abstract
Over the past decade there has been a substantial increase in genetic studies of brain malformations, fueled by the availability of improved technologies to study surgical tissue to address the hypothesis that focal lesions arise from focal, post-zygotic genetic disruptions. Traditional genetic studies of patients with malformations utilized leukocyte-derived DNA to search for germline variants, which are inherited or arise de novo in parental gametes. Recent studies have demonstrated somatic variants that arise post-zygotically also underlie brain malformations, and that somatic mutation explains a larger proportion of focal malformations than previously thought. We now know from studies of non-diseased individuals that somatic variation occurs routinely during cell division, including during early brain development when the rapid proliferation of neuronal precursor cells provides the ideal environment for somatic mutation to occur and somatic variants to accumulate. When confined to brain, pathogenic variants contribute to the "hidden genetics" of neurological diseases. With burgeoning novel high-throughput genetic technologies, somatic genetic variations are increasingly being recognized. Here we discuss accumulating evidence for the presence of somatic variants in normal brain tissue, review our current understanding of somatic variants in brain malformations associated with lesional epilepsy, and provide strategies to identify the potential contribution of somatic mutation to non-lesional epilepsies. We also discuss technologies that may improve detection of somatic variants in the future in these and other neurological conditions.
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Affiliation(s)
- Zimeng Ye
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Lara McQuillan
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, and Department of Neurology, Harvard Medical School, Boston, MA, United States
| | - Timothy E Green
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, WA, United States
| | - Ingrid E Scheffer
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia; Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Parkville, Victoria, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Samuel F Berkovic
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia
| | - Michael S Hildebrand
- Department of Medicine (Austin Hospital), University of Melbourne, Heidelberg, Victoria, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.
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15
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Kim JK, Lee JH. Mechanistic Target of Rapamycin Pathway in Epileptic Disorders. J Korean Neurosurg Soc 2019; 62:272-287. [PMID: 31085953 PMCID: PMC6514310 DOI: 10.3340/jkns.2019.0027] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/12/2019] [Indexed: 12/19/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) pathway coordinates the metabolic activity of eukaryotic cells through environmental signals, including nutrients, energy, growth factors, and oxygen. In the nervous system, the mTOR pathway regulates fundamental biological processes associated with neural development and neurodegeneration. Intriguingly, genes that constitute the mTOR pathway have been found to be germline and somatic mutation from patients with various epileptic disorders. Hyperactivation of the mTOR pathway due to said mutations has garnered increasing attention as culprits of these conditions : somatic mutations, in particular, in epileptic foci have recently been identified as a major genetic cause of intractable focal epilepsy, such as focal cortical dysplasia. Meanwhile, epilepsy models with aberrant activation of the mTOR pathway have helped elucidate the role of the mTOR pathway in epileptogenesis, and evidence from epilepsy models of human mutations recapitulating the features of epileptic patients has indicated that mTOR inhibitors may be of use in treating epilepsy associated with mutations in mTOR pathway genes. Here, we review recent advances in the molecular and genetic understanding of mTOR signaling in epileptic disorders. In particular, we focus on the development of and limitations to therapies targeting the mTOR pathway to treat epileptic seizures. We also discuss future perspectives on mTOR inhibition therapies and special diagnostic methods for intractable epilepsies caused by brain somatic mutations.
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Affiliation(s)
- Jang Keun Kim
- Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Jeong Ho Lee
- Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.,Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
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16
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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: 41] [Impact Index Per Article: 8.2] [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.
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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
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17
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Marsan E, Baulac S. Review: Mechanistic target of rapamycin (mTOR) pathway, focal cortical dysplasia and epilepsy. Neuropathol Appl Neurobiol 2019; 44:6-17. [PMID: 29359340 DOI: 10.1111/nan.12463] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 01/17/2018] [Indexed: 12/19/2022]
Abstract
Over the last decade, there has been increasing evidence that hyperactivation of the mechanistic target of rapamycin (mTOR) pathway is a hallmark of malformations of cortical development such as focal cortical dysplasia (FCD) or hemimegalencephaly. The mTOR pathway governs protein and lipid synthesis, cell growth and proliferation as well as metabolism and autophagy. The molecular genetic aetiology of mTOR hyperactivation has only been recently clarified. This article will review the current and still evolving genetic advances in the elucidation of the molecular basis of FCD. Activating somatic mutations in the MTOR gene are to date the most frequent mutations found in FCD brain specimens.
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Affiliation(s)
- E Marsan
- Department of Genetics and Cytogenetics, AP-HP, Institut du Cerveau et de la Moelle Epinière (ICM) - Hôpital Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Inserm U1127, CNRS UMR 7225, Paris, France
| | - S Baulac
- Department of Genetics and Cytogenetics, AP-HP, Institut du Cerveau et de la Moelle Epinière (ICM) - Hôpital Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Inserm U1127, CNRS UMR 7225, Paris, France
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18
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Juric-Sekhar G, Hevner RF. Malformations of Cerebral Cortex Development: Molecules and Mechanisms. ANNUAL REVIEW OF PATHOLOGY 2019; 14:293-318. [PMID: 30677308 PMCID: PMC6938687 DOI: 10.1146/annurev-pathmechdis-012418-012927] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Malformations of cortical development encompass heterogeneous groups of structural brain anomalies associated with complex neurodevelopmental disorders and diverse genetic and nongenetic etiologies. Recent progress in understanding the genetic basis of brain malformations has been driven by extraordinary advances in DNA sequencing technologies. For example, somatic mosaic mutations that activate mammalian target of rapamycin signaling in cortical progenitor cells during development are now recognized as the cause of hemimegalencephaly and some types of focal cortical dysplasia. In addition, research on brain development has begun to reveal the cellular and molecular bases of cortical gyrification and axon pathway formation, providing better understanding of disorders involving these processes. New neuroimaging techniques with improved resolution have enhanced our ability to characterize subtle malformations, such as those associated with intellectual disability and autism. In this review, we broadly discuss cortical malformations and focus on several for which genetic etiologies have elucidated pathogenesis.
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Affiliation(s)
- Gordana Juric-Sekhar
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington 98195, USA; ,
- Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Robert F Hevner
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington 98195, USA; ,
- Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 98195, USA
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington 98105, USA
- Current affiliation: Department of Pathology, University of California, San Diego, California 92093, USA
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19
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Abstract
Nearly a third of patients with epilepsy have seizures refractory to current medical therapies. In the search for novel drug targets, the mTOR pathway has emerged as key in the regulation of neuronal function, growth and survival, and other cellular processes related to epileptogenesis. Hyperactivation of the mTOR pathway has been implicated in tuberous sclerosis complex and other 'mTORopathies', clinical syndromes associated with cortical developmental malformations and drug-resistant epilepsy. Recently published clinical trials of mTOR inhibitors in tuberous sclerosis complex have shown that these drugs are effective at decreasing seizure frequency. Future studies may establish whether mTOR inhibitors can provide effective treatment for patients with diverse genetic and acquired epilepsies, including preventative, disease-modifying therapies.
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Affiliation(s)
- Jennifer L Griffith
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael Wong
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
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20
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Talos DM, Jacobs LM, Gourmaud S, Coto CA, Sun H, Lim KC, Lucas TH, Davis KA, Martinez-Lage M, Jensen FE. Mechanistic target of rapamycin complex 1 and 2 in human temporal lobe epilepsy. Ann Neurol 2018; 83:311-327. [PMID: 29331082 DOI: 10.1002/ana.25149] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 01/09/2018] [Accepted: 01/10/2018] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Temporal lobe epilepsy (TLE) is a chronic epilepsy syndrome defined by seizures and progressive neurological disabilities, including cognitive impairments, anxiety, and depression. Here, human TLE specimens were investigated focusing on the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) and complex 2 (mTORC2) activities in the brain, given that both pathways may represent unique targets for treatment. METHODS Surgically resected hippocampal and temporal lobe samples from therapy-resistant TLE patients were analyzed by western blotting to quantify the expression of established mTORC1 and mTORC2 activity markers and upstream or downstream signaling pathways involving the two complexes. Histological and immunohistochemical techniques were used to assess hippocampal and neocortical structural abnormalities and cell-specific expression of individual biomarkers. Samples from patients with focal cortical dysplasia (FCD) type II served as positive controls. RESULTS We found significantly increased expression of phospho-mTOR (Ser2448), phospho-S6 (Ser235/236), phospho-S6 (Ser240/244), and phospho-Akt (Ser473) in TLE samples compared to controls, consistent with activation of both mTORC1 and mTORC2. Our work identified the phosphoinositide 3-kinase and Ras/extracellular signal-regulated kinase signaling pathways as potential mTORC1 and mTORC2 upstream activators. In addition, we found that overactive mTORC2 signaling was accompanied by induction of two protein kinase B-dependent prosurvival pathways, as evidenced by increased inhibitory phosphorylation of forkhead box class O3a (Ser253) and glycogen synthase kinase 3 beta (Ser9). INTERPRETATION Our data demonstrate that mTOR signaling is significantly dysregulated in human TLE, offering new targets for pharmacological interventions. Specifically, clinically available drugs that suppress mTORC1 without compromising mTOR2 signaling, such as rapamycin and its analogs, may represent a new group of antiepileptogenic agents in TLE patients. Ann Neurol 2018;83:311-327.
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Affiliation(s)
- Delia M Talos
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Leah M Jacobs
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Sarah Gourmaud
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Carlos A Coto
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Hongyu Sun
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA.,Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Kuei-Cheng Lim
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Timothy H Lucas
- Department of Neurosurgery, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Kathryn A Davis
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Maria Martinez-Lage
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
| | - Frances E Jensen
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA
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21
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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
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22
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Epigallocatechin-3-gallate (EGCG) up-regulates miR-15b expression thus attenuating store operated calcium entry (SOCE) into murine CD4 + T cells and human leukaemic T cell lymphoblasts. Oncotarget 2017; 8:89500-89514. [PMID: 29163766 PMCID: PMC5685687 DOI: 10.18632/oncotarget.20032] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 07/26/2017] [Indexed: 02/05/2023] Open
Abstract
CD4+ T cells are key elements in immune responses and inflammation. Activation of T cell receptors in CD4+ T cells triggers cytosolic Ca2+ release with subsequent store operated Ca2+ entry (SOCE), which is accomplished by the pore forming Ca2+ release activated Ca2+ (CRAC) channel Orai1 and its regulator stromal cell-interaction molecule 2 (STIM2). Green tea polyphenol epigallocatechin-3-gallate (EGCG) acts as a potent anti-inflammatory and anti-oxidant agent for various types of cells including immune cells. However, how post-transcriptional gene regulators such as miRNAs are involved in the regulation of Ca2+ influx into murine CD4+ T cells and human Jurkat T cells through EGCG is not defined. EGCG treatment of murine CD4+ T cells significantly down-regulated the expression of STIM2 and Orai1 both at mRNA and protein levels. Furthermore, EGCG significantly decreased SOCE in both murine and human T cells. EGCG treatment increased miRNA-15b (miR-15b) abundance in both murine and human T cells. Bioinformatics analysis reveals that miR-15b, which has a STIM2 binding site, is involved in the down-regulation of SOCE. Overexpression of miR-15b significantly decreased the mRNA and protein expression of STIM2 and Orai1 in murine T cells. Treatment of Jurkat T cells with 10 μM EGCG further decreased mTOR and PTEN protein levels. EGCG decreased mitochondrial membrane potential (MMP) in both human and murine T cells. In conclusion, the observations suggest that EGCG inhibits the Ca2+ entry into murine and human T cells, an effect accomplished at least in part by up-regulation of miR-15b.
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23
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Mirzaa GM, Campbell CD, Solovieff N, Goold C, Jansen LA, Menon S, Timms AE, Conti V, Biag JD, Adams C, Boyle EA, Collins S, Ishak G, Poliachik S, Girisha KM, Yeung KS, Chung BHY, Rahikkala E, Gunter SA, McDaniel SS, Macmurdo CF, Bernstein JA, Martin B, Leary R, Mahan S, Liu S, Weaver M, Doerschner M, Jhangiani S, Muzny DM, Boerwinkle E, Gibbs RA, Lupski JR, Shendure J, Saneto RP, Novotny EJ, Wilson CJ, Sellers WR, Morrissey M, Hevner RF, Ojemann JG, Guerrini R, Murphy LO, Winckler W, Dobyns WB. Association of MTOR Mutations With Developmental Brain Disorders, Including Megalencephaly, Focal Cortical Dysplasia, and Pigmentary Mosaicism. JAMA Neurol 2017; 73:836-845. [PMID: 27159400 DOI: 10.1001/jamaneurol.2016.0363] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
IMPORTANCE Focal cortical dysplasia (FCD), hemimegalencephaly, and megalencephaly constitute a spectrum of malformations of cortical development with shared neuropathologic features. These disorders are associated with significant childhood morbidity and mortality. OBJECTIVE To identify the underlying molecular cause of FCD, hemimegalencephaly, and diffuse megalencephaly. DESIGN, SETTING, AND PARTICIPANTS Patients with FCD, hemimegalencephaly, or megalencephaly (mean age, 11.7 years; range, 2-32 years) were recruited from Pediatric Hospital A. Meyer, the University of Hong Kong, and Seattle Children's Research Institute from June 2012 to June 2014. Whole-exome sequencing (WES) was performed on 8 children with FCD or hemimegalencephaly using standard-depth (50-60X) sequencing in peripheral samples (blood, saliva, or skin) from the affected child and their parents and deep (150-180X) sequencing in affected brain tissue. Targeted sequencing and WES were used to screen 93 children with molecularly unexplained diffuse or focal brain overgrowth. Histopathologic and functional assays of phosphatidylinositol 3-kinase-AKT (serine/threonine kinase)-mammalian target of rapamycin (mTOR) pathway activity in resected brain tissue and cultured neurons were performed to validate mutations. MAIN OUTCOMES AND MEASURES Whole-exome sequencing and targeted sequencing identified variants associated with this spectrum of developmental brain disorders. RESULTS Low-level mosaic mutations of MTOR were identified in brain tissue in 4 children with FCD type 2a with alternative allele fractions ranging from 0.012 to 0.086. Intermediate-level mosaic mutation of MTOR (p.Thr1977Ile) was also identified in 3 unrelated children with diffuse megalencephaly and pigmentary mosaicism in skin. Finally, a constitutional de novo mutation of MTOR (p.Glu1799Lys) was identified in 3 unrelated children with diffuse megalencephaly and intellectual disability. Molecular and functional analysis in 2 children with FCD2a from whom multiple affected brain tissue samples were available revealed a mutation gradient with an epicenter in the most epileptogenic area. When expressed in cultured neurons, all MTOR mutations identified here drive constitutive activation of mTOR complex 1 and enlarged neuronal size. CONCLUSIONS AND RELEVANCE In this study, mutations of MTOR were associated with a spectrum of brain overgrowth phenotypes extending from FCD type 2a to diffuse megalencephaly, distinguished by different mutations and levels of mosaicism. These mutations may be sufficient to cause cellular hypertrophy in cultured neurons and may provide a demonstration of the pattern of mosaicism in brain and substantiate the link between mosaic mutations of MTOR and pigmentary mosaicism in skin.
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Affiliation(s)
- Ghayda M Mirzaa
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | | | - Nadia Solovieff
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Carleton Goold
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Laura A Jansen
- Department of Neurology, University of Virginia, Charlottesville, VA, USA
| | - Suchithra Menon
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Valerio Conti
- Paediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital, and Department of Neuroscience, Pharmacology and Child Health, University of Florence, Florence, Italy
| | - Jonathan D Biag
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Carissa Adams
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Evan August Boyle
- Department of Genetics, Stanford University School of Medicine, Stanford, California, USA
| | - Sarah Collins
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Gisele Ishak
- Department of Radiology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Sandra Poliachik
- Department of Radiology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
| | - Kit San Yeung
- Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Brian Hon Yin Chung
- Department of Pediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Elisa Rahikkala
- PEDEGO Research Group and Medical Research Center Oulu, University of Oulu and Department of Clinical Genetics, Oulu University Hospital, Finland
| | - Sonya A Gunter
- Department of Neurology, University of Virginia, Charlottesville, VA, USA
| | - Sharon S McDaniel
- Pediatric Neurology and Epilepsy, Kaiser Permanente San Francisco Medical Center, San Francisco, California, USA
| | - Colleen Forsyth Macmurdo
- Division of Medical Genetics, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Jonathan A Bernstein
- Division of Medical Genetics, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Beth Martin
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Rebecca Leary
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Scott Mahan
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Shanming Liu
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Molly Weaver
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Michael Doerschner
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Shalini Jhangiani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Donna M Muzny
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Eric Boerwinkle
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.,Human Genetics Center, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Russell P Saneto
- Division of Pediatric Neurology, University of Washington, Seattle, Washington, USA.,Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle Washington, USA
| | - Edward J Novotny
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Division of Pediatric Neurology, University of Washington, Seattle, Washington, USA
| | | | | | | | - Robert F Hevner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Neurosurgery, University of Washington, Seattle, Washington, USA
| | - Jeffrey G Ojemann
- Department of Neurosurgery, University of Washington, Seattle, Washington, USA
| | - Renzo Guerrini
- Paediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, A. Meyer Children's Hospital, and Department of Neuroscience, Pharmacology and Child Health, University of Florence, Florence, Italy.,IRCCS Stella Maris Foundation, Pisa, Italy
| | - Leon O Murphy
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - Wendy Winckler
- Novartis Institutes for BioMedical Research, Inc., Cambridge, MA
| | - William B Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
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24
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Adler S, Lorio S, Jacques TS, Benova B, Gunny R, Cross JH, Baldeweg T, Carmichael DW. Towards in vivo focal cortical dysplasia phenotyping using quantitative MRI. Neuroimage Clin 2017; 15:95-105. [PMID: 28491496 PMCID: PMC5413300 DOI: 10.1016/j.nicl.2017.04.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/10/2017] [Accepted: 04/18/2017] [Indexed: 12/31/2022]
Abstract
Focal cortical dysplasias (FCDs) are a range of malformations of cortical development each with specific histopathological features. Conventional radiological assessment of standard structural MRI is useful for the localization of lesions but is unable to accurately predict the histopathological features. Quantitative MRI offers the possibility to probe tissue biophysical properties in vivo and may bridge the gap between radiological assessment and ex-vivo histology. This review will cover histological, genetic and radiological features of FCD following the ILAE classification and will explain how quantitative voxel- and surface-based techniques can characterise these features. We will provide an overview of the quantitative MRI measures available, their link with biophysical properties and finally the potential application of quantitative MRI to the problem of FCD subtyping. Future research linking quantitative MRI to FCD histological properties should improve clinical protocols, allow better characterisation of lesions in vivo and tailored surgical planning to the individual.
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Affiliation(s)
- Sophie Adler
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Sara Lorio
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK.
| | - Thomas S Jacques
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Barbora Benova
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, UK; Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic; 2nd Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Roxana Gunny
- Department of Radiology, Great Ormond Street Hospital for Children, London, UK
| | - J Helen Cross
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Torsten Baldeweg
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - David W Carmichael
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
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25
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Scholl T, Mühlebner A, Ricken G, Gruber V, Fabing A, Samueli S, Gröppel G, Dorfer C, Czech T, Hainfellner JA, Prabowo AS, Reinten RJ, Hoogendijk L, Anink JJ, Aronica E, Feucht M. Impaired oligodendroglial turnover is associated with myelin pathology in focal cortical dysplasia and tuberous sclerosis complex. Brain Pathol 2017; 27:770-780. [PMID: 27750396 PMCID: PMC5697648 DOI: 10.1111/bpa.12452] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022] Open
Abstract
Conventional antiepileptic drugs suppress the excessive firing of neurons during seizures. In drug-resistant patients, treatment failure indicates an alternative important epileptogenic trigger. Two epilepsy-associated pathologies show myelin deficiencies in seizure-related brain regions: Focal Cortical Dysplasia IIB (FCD) and cortical tubers in Tuberous Sclerosis Complex (TSC). Studies uncovering white matter-pathology mechanisms are therefore urgently needed to gain more insight into epileptogenesis, the propensity to maintain seizures, and their associated comorbidities such as cognitive defects. We analyzed epilepsy surgery specimens of FCD IIB (n = 22), TSC (n = 8), and other malformations of cortical development MCD (n = 12), and compared them to autopsy and biopsy cases (n = 15). The entire lesional pathology was assessed using digital immunohistochemistry, immunofluorescence and western blotting for oligodendroglial lineage, myelin and mTOR markers, and findings were correlated to clinical parameters. White matter pathology with depleted myelin and oligodendroglia were found in 50% of FCD IIB and 62% of TSC cases. Other MCDs had either a normal content or even showed reactive oligodendrolial hyperplasia. Furthermore, myelin deficiency was associated with increased mTOR expression and the lower amount of oligodendroglia was linked with their precursor cells (PDGFRa). The relative duration of epilepsy (normalized to age) also correlated positively to mTOR activation and negatively to myelination. Decreased content of oligodendroglia and missing precursor cells indicated insufficient oligodendroglial development, probably mediated by mTOR, which may ultimately lead to severe myelin loss. In terms of disease management, an early and targeted treatment could restore normal myelin development and, therefore, alter seizure threshold and improve cognitive outcome.
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Affiliation(s)
- Theresa Scholl
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Angelika Mühlebner
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Gerda Ricken
- Institute of Neurology, Medical University of Vienna, Vienna, Austria
| | - Victoria Gruber
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.,Institute of Neurology, Medical University of Vienna, Vienna, Austria
| | - Anna Fabing
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.,Institute of Neurology, Medical University of Vienna, Vienna, Austria
| | - Sharon Samueli
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Gudrun Gröppel
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Christian Dorfer
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Thomas Czech
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | | | - Avanita S Prabowo
- Department of (Neuro) Pathology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Roy J Reinten
- Department of (Neuro) Pathology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Lisette Hoogendijk
- Department of (Neuro) Pathology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Jasper J Anink
- Department of (Neuro) Pathology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Eleonora Aronica
- Department of (Neuro) Pathology, Academic Medical Centre, Amsterdam, The Netherlands.,Swammerdam Institute for Life Sciences, Centre for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands.,Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Martha Feucht
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
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26
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Shin N, Yi MH, Kim S, Baek H, Triantafillu UL, Park J, Kim DW. Astrocytic Expression of CTMP Following an Excitotoxic Lesion in the Mouse Hippocampus. Exp Neurobiol 2016; 26:25-32. [PMID: 28243164 PMCID: PMC5326712 DOI: 10.5607/en.2017.26.1.25] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/02/2016] [Accepted: 12/07/2016] [Indexed: 01/03/2023] Open
Abstract
Akt (also known as protein kinase B, PKB) has been seen to play a role in astrocyte activation of neuroprotection; however, the underlying mechanism on deregulation of Akt signaling in brain injuries is not fully understood. We investigated the role of carboxy-terminal modulator protein (CTMP), an endogenous Akt inhibitor, in brain injury following kainic acid (KA)-induced neurodegeneration of mouse hippocampus. In control mice, there was a weak signal for CTMP in the hippocampus, but CTMP was markedly increased in the astrocytes 3 days after KA treatment. To further investigate the effectiveness of Akt signaling, the phosphorylation of CTMP was examined. KA treatment induced an increased p-CTMP expression in the astrocytes of hippocampus at 1 day. LPS/IFN-γ-treatment on primary astrocytes promoted the p-CTMP was followed by phosphorylation of Akt and finally upregulation of CTMP and p-CREB. Time-dependent expression of p-CTMP, p-Akt, p-CREB, and CTMP indicate that LPS/IFN-γ-induced phosphorylation of CTMP can activate Akt/CREB signaling, whereas lately emerging enhancement of CTMP can inhibit it. These results suggest that elevation of CTMP in the astrocytes may suppress Akt activity and ultimately negatively affect the outcome of astrocyte activation (astroglisiois). Early time point enhancers of phosphorylation of CTMP and/or late time inhibitors specifically targeting CTMP may be beneficial in astrocyte activation for neuroprotection within treatment in neuroinflammatory conditions.
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Affiliation(s)
- Nara Shin
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea.; Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Min-Hee Yi
- Department of Neuroscience & Cell Biology, the University of Texas Medical Branch School of Medicine, Galveston, TX 77555 USA
| | - Sena Kim
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Hyunjung Baek
- Department of Physiology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Ursula L Triantafillu
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, AL, USA
| | - Jongsun Park
- Department of Pharmacology, Chungnam National University School of Medicine, Daejeon 35015, Korea.; Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea
| | - Dong Woon Kim
- Department of Anatomy, Brain Research Institute, Chungnam National University School of Medicine, Daejeon 35015, Korea.; Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Korea
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27
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Rossini L, Villani F, Granata T, Tassi L, Tringali G, Cardinale F, Aronica E, Spreafico R, Garbelli R. FCD Type II and mTOR pathway: Evidence for different mechanisms involved in the pathogenesis of dysmorphic neurons. Epilepsy Res 2016; 129:146-156. [PMID: 28056425 DOI: 10.1016/j.eplepsyres.2016.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 11/24/2016] [Accepted: 12/06/2016] [Indexed: 12/19/2022]
Abstract
Type II focal cortical dysplasia (FCD II) is a malformation of cortical development, frequently associated with intractable epilepsy, characterised by cortical dyslamination, dysmorphic neurons (DNs) and balloon cells (BCs). We investigated the expression of pS6 (downstream target) and pPDK1-pAkt (upstream targets) as evidence for mTOR pathway activation and their co-expression with Interleukin-1β in FCD II surgical specimens and compared the findings with control non-epileptic tissue, non-malformed epileptic tissue or acquired epilepsy-Rasmussen's Encephalitis (RE) occasionally presenting pS6 and Interleukin-1β positive abnormal neurons. Downstream mTOR activation was demonstrated in almost all abnormal cells in both FCD II and RE. Conversely, upstream activation in FCD II was observed in the majority of BCs, in a proportion of DNs, not presenting Interleukin-1β expression, but not at all in RE scattered abnormal neurons. Based on these findings we suggest that the presence of BCs and DNs in FCD II could be due to a first upstream mTOR pathway PI3K-Akt-mediate event occurring very early during cortical development in the large proportion of abnormal cells; followed by the appearance of additional pS6 positive DNs promoted by the presence of a later inflammatory processes.
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Affiliation(s)
- Laura Rossini
- Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS, Istituto Neurologico "C. Besta", Milan, Italy.
| | - Flavio Villani
- Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS, Istituto Neurologico "C. Besta", Milan, Italy
| | - Tiziana Granata
- Department of Pediatric Neuroscience, Fondazione IRCCS, Istituto Neurologico "C. Besta", Milan, Italy
| | - Laura Tassi
- Epilepsy Surgery Centre "C. Munari", Ospedale Niguarda, Milan, Italy
| | - Giovanni Tringali
- Neurosurgery Unit, Fondazione IRCCS, Istituto Neurologico "C. Besta", Milan, Italy
| | | | - Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience University of Amsterdam; Stichting Epilepsie Instellingen Nederland (SEIN), The Netherlands
| | - Roberto Spreafico
- Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS, Istituto Neurologico "C. Besta", Milan, Italy
| | - Rita Garbelli
- Clinical Epileptology and Experimental Neurophysiology Unit, Fondazione IRCCS, Istituto Neurologico "C. Besta", Milan, Italy
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28
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Chen Y, Cai M, Deng J, Tian L, Wang S, Tong L, Dong H, Xiong L. Elevated Expression of Carboxy-Terminal Modulator Protein (CTMP) Aggravates Brain Ischemic Injury in Diabetic db/db Mice. Neurochem Res 2016; 41:2179-89. [PMID: 27161366 DOI: 10.1007/s11064-016-1932-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/04/2016] [Accepted: 04/20/2016] [Indexed: 12/13/2022]
Abstract
Deregulation of Akt signaling is important in the brain injuries caused by cerebral ischemia in diabetic animals, and the underlying mechanism is not fully understood. We investigated the role of carboxy-terminal modulator protein (CTMP), an endogenous Akt inhibitor, in brain injury following focal cerebral ischemia in type 2 diabetic db/db mice and their control littermates non-diabetic db/+ mice. db/db mice showed a significant elevation in the expression of CTMP compared to db/+ mice under normal physiological conditions. After ischemia, db/db mice exhibit higher levels of CTMP expression, decreased Akt kinase activity, adverse neurological deficits and cerebral infarction than db/+ mice. To further certain the effectiveness of Akt signaling to the final outcome of cerebral ischemia, the animals were treated with LY294002, an inhibitor of the Akt pathway, which aggravated the ischemic injury in db/+ mice but not in db/db mice. RNA interference-mediated depletion of CTMP were finally applied in db/db mice, which restored Akt activity, improved neurological scores and reduced infarct volume. These results suggest that elevation of CTMP in diabetic mice suppresses Akt activity and ultimately negatively affects the outcome of ischemia. Inhibitors specifically targeting CTMP may be beneficial in the treatment of cerebral ischemia in patients with diabetes.
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Affiliation(s)
- Yu Chen
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Min Cai
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Jiao Deng
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Li Tian
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Shiquan Wang
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Li Tong
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China
| | - Hailong Dong
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China. .,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.
| | - Lize Xiong
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China. .,Department of Psychiatry, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.
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Nakashima M, Saitsu H, Takei N, Tohyama J, Kato M, Kitaura H, Shiina M, Shirozu H, Masuda H, Watanabe K, Ohba C, Tsurusaki Y, Miyake N, Zheng Y, Sato T, Takebayashi H, Ogata K, Kameyama S, Kakita A, Matsumoto N. Somatic Mutations in the MTOR gene cause focal cortical dysplasia type IIb. Ann Neurol 2015; 78:375-86. [PMID: 26018084 DOI: 10.1002/ana.24444] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 05/26/2015] [Accepted: 05/26/2015] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Focal cortical dysplasia (FCD) type IIb is a cortical malformation characterized by cortical architectural abnormalities, dysmorphic neurons, and balloon cells. It has been suggested that FCDs are caused by somatic mutations in cells in the developing brain. Here, we explore the possible involvement of somatic mutations in FCD type IIb. METHODS We collected a total of 24 blood-brain paired samples with FCD, including 13 individuals with FCD type IIb, 5 with type IIa, and 6 with type I. We performed whole-exome sequencing using paired samples from 9 of the FCD type IIb subjects. Somatic MTOR mutations were identified and further investigated using all 24 paired samples by deep sequencing of the entire gene's coding region. Somatic MTOR mutations were confirmed by droplet digital polymerase chain reaction. The effect of MTOR mutations on mammalian target of rapamycin (mTOR) kinase signaling was evaluated by immunohistochemistry and Western blotting analyses of brain samples and by in vitro transfection experiments. RESULTS We identified four lesion-specific somatic MTOR mutations in 6 of 13 (46%) individuals with FCD type IIb showing mutant allele rates of 1.11% to 9.31%. Functional analyses showed that phosphorylation of ribosomal protein S6 in FCD type IIb brain tissues with MTOR mutations was clearly elevated, compared to control samples. Transfection of any of the four MTOR mutants into HEK293T cells led to elevated phosphorylation of 4EBP, the direct target of mTOR kinase. INTERPRETATION We found low-prevalence somatic mutations in MTOR in FCD type IIb, indicating that activating somatic mutations in MTOR cause FCD type IIb.
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Affiliation(s)
- Mitsuko Nakashima
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hirotomo Saitsu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Nobuyuki Takei
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Jun Tohyama
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Hiroki Kitaura
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Masaaki Shiina
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hiroshi Shirozu
- Department of Functional Neurosurgery, Epilepsy Center, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Hiroshi Masuda
- Department of Functional Neurosurgery, Epilepsy Center, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Keisuke Watanabe
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Chihiro Ohba
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yoshinori Tsurusaki
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Yingjun Zheng
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Tatsuhiro Sato
- Division of Biochemistry, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Kazuhiro Ogata
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Shigeki Kameyama
- Department of Functional Neurosurgery, Epilepsy Center, Nishi-Niigata Chuo National Hospital, Niigata, Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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Lin YX, Lin K, Kang DZ, Liu XX, Wang XF, Zheng SF, Yu LH, Lin ZY. Similar PDK1–AKT–mTOR pathway activation in balloon cells and dysmorphic neurons of type II focal cortical dysplasia with refractory epilepsy. Epilepsy Res 2015; 112:137-49. [DOI: 10.1016/j.eplepsyres.2015.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 01/25/2015] [Accepted: 02/06/2015] [Indexed: 11/30/2022]
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31
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Jansen LA, Mirzaa GM, Ishak GE, O'Roak BJ, Hiatt JB, Roden WH, Gunter SA, Christian SL, Collins S, Adams C, Rivière JB, St-Onge J, Ojemann JG, Shendure J, Hevner RF, Dobyns WB. PI3K/AKT pathway mutations cause a spectrum of brain malformations from megalencephaly to focal cortical dysplasia. Brain 2015; 138:1613-28. [PMID: 25722288 DOI: 10.1093/brain/awv045] [Citation(s) in RCA: 241] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/22/2014] [Indexed: 11/15/2022] Open
Abstract
Malformations of cortical development containing dysplastic neuronal and glial elements, including hemimegalencephaly and focal cortical dysplasia, are common causes of intractable paediatric epilepsy. In this study we performed multiplex targeted sequencing of 10 genes in the PI3K/AKT pathway on brain tissue from 33 children who underwent surgical resection of dysplastic cortex for the treatment of intractable epilepsy. Sequencing results were correlated with clinical, imaging, pathological and immunohistological phenotypes. We identified mosaic activating mutations in PIK3CA and AKT3 in this cohort, including cancer-associated hotspot PIK3CA mutations in dysplastic megalencephaly, hemimegalencephaly, and focal cortical dysplasia type IIa. In addition, a germline PTEN mutation was identified in a male with hemimegalencephaly but no peripheral manifestations of the PTEN hamartoma tumour syndrome. A spectrum of clinical, imaging and pathological abnormalities was found in this cohort. While patients with more severe brain imaging abnormalities and systemic manifestations were more likely to have detected mutations, routine histopathological studies did not predict mutation status. In addition, elevated levels of phosphorylated S6 ribosomal protein were identified in both neurons and astrocytes of all hemimegalencephaly and focal cortical dysplasia type II specimens, regardless of the presence or absence of detected PI3K/AKT pathway mutations. In contrast, expression patterns of the T308 and S473 phosphorylated forms of AKT and in vitro AKT kinase activities discriminated between mutation-positive dysplasia cortex, mutation-negative dysplasia cortex, and non-dysplasia epilepsy cortex. Our findings identify PI3K/AKT pathway mutations as an important cause of epileptogenic brain malformations and establish megalencephaly, hemimegalencephaly, and focal cortical dysplasia as part of a single pathogenic spectrum.
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Affiliation(s)
- Laura A Jansen
- 1 University of Virginia, Neurology, Charlottesville, VA, USA 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA
| | - Ghayda M Mirzaa
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA 3 University of Washington, Paediatrics, Seattle, WA, USA
| | - Gisele E Ishak
- 4 Seattle Children's Hospital, Radiology, Seattle, WA, USA
| | - Brian J O'Roak
- 5 University of Washington, Genome Sciences, Seattle, WA, USA 6 Oregon Health and Science University, Molecular and Medical Genetics, Portland, OR, USA
| | - Joseph B Hiatt
- 5 University of Washington, Genome Sciences, Seattle, WA, USA
| | - William H Roden
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA
| | - Sonya A Gunter
- 1 University of Virginia, Neurology, Charlottesville, VA, USA
| | - Susan L Christian
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA
| | - Sarah Collins
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA
| | - Carissa Adams
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA
| | - Jean-Baptiste Rivière
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA 7 Université de Bourgogne, Equipe Génétique des Anomalies du Développement, Dijon, France
| | - Judith St-Onge
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA 7 Université de Bourgogne, Equipe Génétique des Anomalies du Développement, Dijon, France
| | | | - Jay Shendure
- 5 University of Washington, Genome Sciences, Seattle, WA, USA
| | - Robert F Hevner
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA 8 University of Washington, Neurosurgery, Seattle, WA, USA
| | - William B Dobyns
- 2 Seattle Children's Research Institute, Centre for Integrative Brain Research, Seattle, WA, USA 3 University of Washington, Paediatrics, Seattle, WA, USA
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32
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Waugh MG. PIPs in neurological diseases. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1066-82. [PMID: 25680866 DOI: 10.1016/j.bbalip.2015.02.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/29/2015] [Accepted: 02/01/2015] [Indexed: 12/19/2022]
Abstract
Phosphoinositide (PIP) lipids regulate many aspects of cell function in the nervous system including receptor signalling, secretion, endocytosis, migration and survival. Levels of PIPs such as PI4P, PI(4,5)P2 and PI(3,4,5)P3 are normally tightly regulated by phosphoinositide kinases and phosphatases. Deregulation of these biochemical pathways leads to lipid imbalances, usually on intracellular endosomal membranes, and these changes have been linked to a number of major neurological diseases including Alzheimer's, Parkinson's, epilepsy, stroke, cancer and a range of rarer inherited disorders including brain overgrowth syndromes, Charcot-Marie-Tooth neuropathies and neurodevelopmental conditions such as Lowe's syndrome. This article analyses recent progress in this area and explains how PIP lipids are involved, to varying degrees, in almost every class of neurological disease. This article is part of a Special Issue entitled Brain Lipids.
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Affiliation(s)
- Mark G Waugh
- Lipid and Membrane Biology Group, Institute for Liver and Digestive Health, UCL, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom.
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33
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Abstract
Disorders of brain overgrowth are significant causes of intractable epilepsy, intellectual disability, autism, and other complex neurological problems. The pathology of these disorders is sometimes striking and characteristic, as in hemimegalencephaly, but can also be subtle, as in autism. Recent genetic studies have shown that many diverse forms of brain overgrowth are caused by de novo mutations that increase activity in the receptor tyrosine kinase (RTK)-phosphatidylinositol-3-kinase (PI3K)-AKT signaling pathway, a key mediator of signaling by growth factors in the developing brain, such as fibroblast growth factors. In cases where mutations arise in postzygotic embryos, brain regions exhibit mosaic pathology that reflects the distribution of mutant cells, ranging from focal cortical dysplasia to lobar or hemispheric overgrowth. In turn, the histopathology of these disorders is also remarkably varied. The common underlying mechanisms of RTK-PI3K-AKT overactivation suggest new possibilities for drugs that inhibit this pathway.
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Affiliation(s)
- Robert F. Hevner
- Departments of Neurological Surgery and Pathology, University of Washington School of Medicine, Seattle, WA
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34
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Surgery for focal cortical dysplasia in children using intraoperative mapping. Childs Nerv Syst 2014; 30:1839-51. [PMID: 25296545 DOI: 10.1007/s00381-014-2459-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Children with malformation of cortical development represent a significant proportion of pediatric epilepsy surgery candidates. Here, we describe a single-center experience with pediatric patients who underwent surgery for intractable epilepsy due to focal cortical dysplasia (FCD). METHODS Clinical data of 78 patients under 18 years of age with diagnosis of intractable epilepsy due to FCD who underwent surgery from January 1996 to January 2012 were reviewed comparing data of patients submitted to electrocorticography (ECoG) with those without ECoG. RESULTS Patients' mean age at surgery was 8.52 ± 4.99 years; mean age at epilepsy onset was 2.55 ± 3.01 years. Almost 80 % of the patients underwent ECoG register that was essential for delimitation of surgical resection in 66 out of 78 patients. ECoG was performed in all patients with extratemporal lesions, and the most common FCD found was type II. Seizure outcome was similar in groups with or without ECoG. CONCLUSIONS Tailored resection of FCD lesions for intractable epilepsy can be safely performed in children with a good seizure outcome and low complication rate. Epilepsy surgery should be considered for all patients with FCD and refractory epilepsy.
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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.
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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
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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.
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Affiliation(s)
- Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Amsterdam
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37
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Compensatory network alterations upon onset of epilepsy in synapsin triple knock-out mice. Neuroscience 2011; 189:108-22. [PMID: 21621590 DOI: 10.1016/j.neuroscience.2011.05.030] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 04/16/2011] [Accepted: 05/11/2011] [Indexed: 11/21/2022]
Abstract
Adult synapsin triple-knockout mice exhibit epilepsy that manifests as generalized tonic-clonic seizures. Because in vitro recordings have shown a reduction in quantal release from inhibitory neurons, an inherent excitation-inhibition imbalance has been hypothesized as the direct culprit for epilepsy in these mice. We critically assessed this hypothesis by examining neurotransmission during the emergence of epilepsy. Using long-term video and telemetric EEG monitoring we found that synapsin triple-knockout mice exhibit an abrupt transition during early adulthood from a seizure-free presymptomatic latent state to a consistent symptomatic state of sensory-induced seizures. Electrophysiological recordings showed that during the latent period larger field responses could be elicited in slices from mutant mice. However, only after the transition to a symptomatic state in the adult mice did evoked epileptiform activity become prevalent. This state was characterized by resistance to the epileptiform-promoting effects of 4-aminopyridine, by marked hypersensitivity to blockage of GABAA receptors, and by the emergence of unresponsiveness to NMDA receptor antagonism, all of which were not observed during the latent period. Importantly, enhancement in inhibitory transmission was associated with upregulation of GAD67 expression without affecting the number of inhibitory neurons in the same brain areas where epileptiform activity was recorded. We therefore suggest that while deletion of the synapsins initially increases cortical network activity, this enhanced excitability is insufficient to elicit seizures. Rather, compensatory epileptogenic mechanisms are activated during the latent period that lead to an additional almost-balanced enhancement of both the excitatory and inhibitory components of the network, finally culminating in the emergence of epilepsy.
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38
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Sisodiya SM, Fauser S, Cross JH, Thom M. Focal cortical dysplasia type II: biological features and clinical perspectives. Lancet Neurol 2009; 8:830-43. [DOI: 10.1016/s1474-4422(09)70201-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Fassunke J, Majores M, Tresch A, Niehusmann P, Grote A, Schoch S, Becker AJ. Array analysis of epilepsy-associated gangliogliomas reveals expression patterns related to aberrant development of neuronal precursors. ACTA ACUST UNITED AC 2008; 131:3034-50. [PMID: 18819986 DOI: 10.1093/brain/awn233] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Gangliogliomas, the most frequent neoplasms in patients with pharmacoresistant focal epilepsies, are characterized by histological combinations of glial and dysplastic neuronal elements, a highly differentiated phenotype and rare gene mutations. Their molecular basis and relationship to other low-grade brain tumours are not completely understood. Systematic investigations of altered gene expression in gangliogliomas have been hampered by their cellular complexity, the lack of suitable control tissue and of sensitive expression profiling approaches. Here, we have used discrete microdissected ganglioglioma and adjacent control brain tissue obtained from the neurosurgical access to the tumour of identical patients (n = 6) carefully matched for equivalent glial and neuronal elements in an amount sufficient for oligonucleotide microarray hybridization without repetitive amplification. Multivariate statistical analysis identified a rich profile of genes with altered expression in gangliogliomas. Many differentially expressed transcripts related to intra- and intercellular signalling including protein kinase C and its target NELL2 in identical ganglioglioma cell components as determined by real-time quantitative RT-PCR (qRT-PCR) and in situ hybridization. We observed the LIM-domain-binding 2 (LDB2) transcript, critical for brain development during embryogenesis, as one of the strongest reduced mRNAs in gangliogliomas. Subsequent qRT-PCR in dysembryoplastic neuroepithelial tumours (n = 7) revealed partial expression similarities as well as marked differences from gangliogliomas. The demonstrated gene expression profile differentiates gangliogliomas from other low-grade primary brain tumours. shRNA-mediated silencing of LDB2 resulted in substantially aberrant dendritic arborization in cultured developing primary hippocampal neurons. The present data characterize novel molecular mechanisms operating in gangliogliomas that contribute to the development of dysplastic neurons and an aberrant neuronal network.
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Affiliation(s)
- Jana Fassunke
- Department of Neuropathology, University of Bonn Medical Center, Bonn, Germany
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Calzavara E, Chiaramonte R, Cesana D, Basile A, Sherbet GV, Comi P. Reciprocal regulation of Notch and PI3K/Akt signalling in T-ALL cells In Vitro. J Cell Biochem 2008; 103:1405-12. [PMID: 17849443 DOI: 10.1002/jcb.21527] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Notch signalling plays an important role in hematopoiesis and in the pathogenesis of T-ALL. Notch is known to interact with Ras and PTEN/PI3K (phosphoinositide-3 kinase)/Akt pathways. We investigated the interaction of Notch with these pathways and the possible reciprocal regulation of these signalling systems in T-ALL cells in vitro. Our analyses indicate that the PI3K/Akt pathway is constitutively active in the four T-ALL cell lines tested. Akt phosphorylation was not altered by the sequestration of growth factors, that is, Akt activation seems to be less dependent on but not completely independent of growth factors, possibly being not subject to negative feedback regulation. PTEN expression was not detected in 3/4 cell lines tested, suggesting the loss of PTEN-mediated Akt activation. Inhibition of the PI3K/Akt pathway arrests growth and enhances apoptosis, but with no modulation of expression of Bax-alpha and Bcl-2 proteins. We analysed the relationship between Notch-1 and the PI3K/Akt signalling and show that inhibition of the Akt pathway changes Notch expression; Notch-1 protein decreased in all the cell lines upon treatment with the inhibitor. Our studies strongly suggest that Notch signalling interacts with PI3K/Akt signalling and further that this occurs in the absence of PTEN expression. The consequences of this to the signalling outcome are yet unclear, but we have uncovered a significant inverse relationship between Notch and PI3K/Akt pathway, which leads us to postulate the operation of a reciprocal regulatory loop between Notch and Ras-PI3K/Akt in the pathogenesis of T-ALL.
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Affiliation(s)
- Elisabetta Calzavara
- Department of Biomedical Sciences and Technologies, University of Milano, LITA, via Fratelli Cevi 93, 20090 Segrate (MI), Italy
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An investigation of the expression of G1-phase cell cycle proteins in focal cortical dysplasia type IIB. J Neuropathol Exp Neurol 2007; 66:1045-55. [PMID: 17984686 DOI: 10.1097/nen.0b013e3181598d23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Balloon cells (BCs) are the pathologic hallmark of focal cortical dysplasia type IIB, a common cause of pharmacoresistent epilepsy. Expression of markers of cell immaturity and of the proliferation marker minichromosome maintenance protein 2 (mcm2) have been previously shown in BCs, suggesting that these cells might represent a pool of less-differentiated cells licensed for replication. An alternative explanation is that these cells are the remnants of early cortical plate cells that have failed to differentiate or to be eliminated during development and are arrested in the cell cycle, a hypothesis that this study aims to explore. Using immunohistochemical methods and semiquantitative analysis in 19 cases of focal cortical dysplasia (ages 1-81 years), we studied the expression of cell cycle proteins important either in regulating progression through the G1 phase or inducing cell arrest and promoting premature senescence. Only a small fraction of BCs expressed geminin, suggesting that few BCs enter the S phase or complete the cell cycle. Variable expression of nonphosphorylated retinoblastoma protein (Rb), cdk4, and p53 was noted in BCs. Cyclin E, D1, cdk2, phosphorylated Rb (795 and 807/811), and checkpoint 2 expression levels were low in BCs. These findings suggest early rather than late G1 arrest. Cell senescence could be induced by an undefined cerebral insult during development or alternatively represent a physiologic replicative senescence. These findings also suggest that dysregulation of cell cycle pathways may occur in focal cortical dysplasia, which opens further areas for exploration as potential new treatment avenues.
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Franke TF. Akt-interacting proteins: attractive opposites. focus on "Carboxy-terminal modulator protein induces Akt phosphorylation and activation, thereby enhancing antiapoptotic, glycogen synthetic, and glucose uptake pathways". Am J Physiol Cell Physiol 2007; 293:C1768-70. [PMID: 17913839 DOI: 10.1152/ajpcell.00451.2007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Thomas F Franke
- Department of Psychiatry, Milhauser Laboratories, NYU School of Medicine, New York, NY 10016, usa.
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43
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Aronica E, Boer K, Baybis M, Yu J, Crino P. Co-expression of cyclin D1 and phosphorylated ribosomal S6 proteins in hemimegalencephaly. Acta Neuropathol 2007; 114:287-93. [PMID: 17483958 DOI: 10.1007/s00401-007-0225-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 04/07/2007] [Accepted: 04/08/2007] [Indexed: 02/05/2023]
Abstract
Hemimegalencephaly (HMEG) is a developmental brain malformation highly associated with epilepsy. Balloon cells (BCs) and cytomegalic neurons (CNs) are frequently observed in HMEG specimens. Cytomegaly in developmental brain malformations may reflect in aberrant activation of the mTOR and beta-catenin signaling cascades, known regulators of cell size. We hypothesized that there is aberrant co-expression of phospho-ribosomal S6 (P-S6) protein, a downstream effector of the mTOR cascade, as well as cyclin D1, a downstream effector of the beta-catenin pathway, in BCs and cytomegalic neurons in HMEG. We hypothesized that mutations in PTEN (a cause of HMEG associated with Proteus syndrome), TSC1 or TSC2 (tuberous sclerosis complex) genes, which are known to modulate beta-catenin and mTOR signaling could cause sporadic HMEG. Expression of cyclin D1, phospho-p70 S6 kinase (P-p70S6K, another mTOR cascade kinase), P-S6, MAP2, NeuN, or GFAP was determined by immunohistochemistry in HMEG brain tissue (n = 7 specimens). Cyclin D1, P-p70S6K, and P-S6 proteins were co-localized in BCs and CNs in the enlarged hemisphere but not in the unaffected hemisphere or in morphologically normal tissue. Cyclin D1 and P-S6 proteins were not detected in GFAP-labeled astrocytes. Sequencing of PTEN, TSC1, and TSC2 genes in cytomegalic cells co-expressing cyclin D1 and P-S6 proteins did not reveal mutations. Selective expression of cyclin D1 and P-S6 in cytomegalic cells in HMEG suggests co-activation of the beta-catenin and mTOR cascades. PTEN, TSC1, or TSC2 gene mutations were not detected suggesting that sporadic HMEG is distinct from HMEG associated with Proteus syndrome or tuberous sclerosis complex.
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Affiliation(s)
- Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Schick V, Majores M, Engels G, Hartmann W, Elger CE, Schramm J, Schoch S, Becker AJ. Differential Pi3K-pathway activation in cortical tubers and focal cortical dysplasias with balloon cells. Brain Pathol 2007; 17:165-73. [PMID: 17388947 PMCID: PMC8095540 DOI: 10.1111/j.1750-3639.2007.00059.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Balloon cells of distinct focal cortical dysplasias type IIb (FCD(IIb)) and giant cells of cortical tubers in tuberous sclerosis (TSC) constitute neuropathological hallmarks and cytological similarities. In TSC, frequent mutations in the TSC1 or TSC2 genes result in mTOR-signaling activity. Here, we addressed whether Pi3K-pathway activation differentiates balloon cells from giant cells. We used immunohistochemistry with antibodies against p-PDK1 (S241), p-Akt (S473), p-tuberin (T1462), p-p70(S6K) (T389), p-p70(S6K) (T229) and phalloidin-staining to analyze stress fiber formation in balloon cells of FCD(IIb) (n = 23) compared with cortical tuber giant cells (n = 5) and adjacent normal CNS tissue as control. We have further established an in vitro assay to assess potential phosphorylation between Akt and S6. We observed phosphorylated (p-)PDK1, p-Akt, p-tuberin, and p-p70-kDa S6-kinase (p-p70(S6K); residue T229) in balloon cells, whereas giant cells showed only equivalent levels of p-tuberin, p-p70(S6K) and stress fibers. Furthermore, Pi3K-cascade activity in balloon cells may reflect pathway "cross-talk". An in vitro assay revealed S6, a major target of p70(S6K), to increase phosphorylation of Akt. Our data suggest recruitment of different Pi3K-cascade factors in the molecular pathogenesis of giant cells in cortical tubers vs. balloon cells in FCD(IIb) and provides new implications for the development of treatment strategies for these cortical malformations.
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