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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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Danačíková Š, Straka B, Daněk J, Kořínek V, Otáhal J. In vitro human cell culture models in a bench-to-bedside approach to epilepsy. Epilepsia Open 2024; 9:865-890. [PMID: 38637998 PMCID: PMC11145627 DOI: 10.1002/epi4.12941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/05/2024] [Accepted: 03/31/2024] [Indexed: 04/20/2024] Open
Abstract
Epilepsy is the most common chronic neurological disease, affecting nearly 1%-2% of the world's population. Current pharmacological treatment and regimen adjustments are aimed at controlling seizures; however, they are ineffective in one-third of the patients. Although neuronal hyperexcitability was previously thought to be mainly due to ion channel alterations, current research has revealed other contributing molecular pathways, including processes involved in cellular signaling, energy metabolism, protein synthesis, axon guidance, inflammation, and others. Some forms of drug-resistant epilepsy are caused by genetic defects that constitute potential targets for precision therapy. Although such approaches are increasingly important, they are still in the early stages of development. This review aims to provide a summary of practical aspects of the employment of in vitro human cell culture models in epilepsy diagnosis, treatment, and research. First, we briefly summarize the genetic testing that may result in the detection of candidate pathogenic variants in genes involved in epilepsy pathogenesis. Consequently, we review existing in vitro cell models, including induced pluripotent stem cells and differentiated neuronal cells, providing their specific properties, validity, and employment in research pipelines. We cover two methodological approaches. The first approach involves the utilization of somatic cells directly obtained from individual patients, while the second approach entails the utilization of characterized cell lines. The models are evaluated in terms of their research and clinical benefits, relevance to the in vivo conditions, legal and ethical aspects, time and cost demands, and available published data. Despite the methodological, temporal, and financial demands of the reviewed models they possess high potential to be used as robust systems in routine testing of pathogenicity of detected variants in the near future and provide a solid experimental background for personalized therapy of genetic epilepsies. PLAIN LANGUAGE SUMMARY: Epilepsy affects millions worldwide, but current treatments fail for many patients. Beyond traditional ion channel alterations, various genetic factors contribute to the disorder's complexity. This review explores how in vitro human cell models, either from patients or from cell lines, can aid in understanding epilepsy's genetic roots and developing personalized therapies. While these models require further investigation, they offer hope for improved diagnosis and treatment of genetic forms of epilepsy.
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Affiliation(s)
- Šárka Danačíková
- Laboratory of Developmental EpileptologyInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
- Department of Pathophysiology, Second Faculty of MedicineCharles UniversityPragueCzech Republic
- Laboratory of Cell and Developmental BiologyInstitute of Molecular Genetics of the Czech Academy of SciencesPragueCzech Republic
- Department of Physiology, Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Barbora Straka
- Neurogenetics Laboratory of the Department of Paediatric Neurology, Second Faculty of MedicineCharles University and Motol University Hospital, Full Member of the ERN EpiCAREPragueCzech Republic
| | - Jan Daněk
- Laboratory of Developmental EpileptologyInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
| | - Vladimír Kořínek
- Laboratory of Cell and Developmental BiologyInstitute of Molecular Genetics of the Czech Academy of SciencesPragueCzech Republic
| | - Jakub Otáhal
- Laboratory of Developmental EpileptologyInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
- Department of Pathophysiology, Second Faculty of MedicineCharles UniversityPragueCzech Republic
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3
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Levitin MO, Rawlins LE, Sanchez-Andrade G, Arshad OA, Collins SC, Sawiak SJ, Iffland PH, Andersson MHL, Bupp C, Cambridge EL, Coomber EL, Ellis I, Herkert JC, Ironfield H, Jory L, Kretz PF, Kant SG, Neaverson A, Nibbeling E, Rowley C, Relton E, Sanderson M, Scott EM, Stewart H, Shuen AY, Schreiber J, Tuck L, Tonks J, Terkelsen T, van Ravenswaaij-Arts C, Vasudevan P, Wenger O, Wright M, Day A, Hunter A, Patel M, Lelliott CJ, Crino PB, Yalcin B, Crosby AH, Baple EL, Logan DW, Hurles ME, Gerety SS. Models of KPTN-related disorder implicate mTOR signalling in cognitive and overgrowth phenotypes. Brain 2023; 146:4766-4783. [PMID: 37437211 PMCID: PMC10629792 DOI: 10.1093/brain/awad231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 05/31/2023] [Accepted: 06/18/2023] [Indexed: 07/14/2023] Open
Abstract
KPTN-related disorder is an autosomal recessive disorder associated with germline variants in KPTN (previously known as kaptin), a component of the mTOR regulatory complex KICSTOR. To gain further insights into the pathogenesis of KPTN-related disorder, we analysed mouse knockout and human stem cell KPTN loss-of-function models. Kptn -/- mice display many of the key KPTN-related disorder phenotypes, including brain overgrowth, behavioural abnormalities, and cognitive deficits. By assessment of affected individuals, we have identified widespread cognitive deficits (n = 6) and postnatal onset of brain overgrowth (n = 19). By analysing head size data from their parents (n = 24), we have identified a previously unrecognized KPTN dosage-sensitivity, resulting in increased head circumference in heterozygous carriers of pathogenic KPTN variants. Molecular and structural analysis of Kptn-/- mice revealed pathological changes, including differences in brain size, shape and cell numbers primarily due to abnormal postnatal brain development. Both the mouse and differentiated induced pluripotent stem cell models of the disorder display transcriptional and biochemical evidence for altered mTOR pathway signalling, supporting the role of KPTN in regulating mTORC1. By treatment in our KPTN mouse model, we found that the increased mTOR signalling downstream of KPTN is rapamycin sensitive, highlighting possible therapeutic avenues with currently available mTOR inhibitors. These findings place KPTN-related disorder in the broader group of mTORC1-related disorders affecting brain structure, cognitive function and network integrity.
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Affiliation(s)
- Maria O Levitin
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Evox Therapeutics Limited, Oxford OX4 4HG, UK
| | - Lettie E Rawlins
- RILD Wellcome Wolfson Medical Research Centre, University of Exeter, Exeter EX2 5DW, UK
- Peninsula Clinical Genetics Service, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX1 2ED, UK
| | | | - Osama A Arshad
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Stephan C Collins
- INSERM Unit 1231, Université de Bourgogne Franche-Comté, Dijon 21078, France
| | - Stephen J Sawiak
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Phillip H Iffland
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Malin H L Andersson
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Caleb Bupp
- Spectrum Health, Helen DeVos Children’s Hospital, Grand Rapids, MI 49503, USA
| | - Emma L Cambridge
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Eve L Coomber
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Ian Ellis
- Department of Clinical Genetics, Alder Hey Children’s Hospital, Liverpool L14 5AB, UK
| | - Johanna C Herkert
- Department of Genetics, University Medical Centre, University of Groningen, Groningen 9713 GZ, The Netherlands
| | - Holly Ironfield
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Logan Jory
- Haven Clinical Psychology Practice Ltd, Bude, Cornwall EX23 9HP, UK
| | | | - Sarina G Kant
- Department of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam 3015 GD, The Netherlands
- Department of Clinical Genetics, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
| | - Alexandra Neaverson
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Esther Nibbeling
- Laboratory for Diagnostic Genome Analysis, Department of Clinical Genetics, Leiden University Medical Center, Leiden 3015 GD, The Netherlands
| | - Christine Rowley
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Institute of Metabolic Science, Cambridge University, Cambridge CB2 0QQ, UK
| | - Emily Relton
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Faculty of Health and Medical Science, University of Surrey, Guildford GU2 7YH, UK
| | - Mark Sanderson
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Ethan M Scott
- New Leaf Center, Clinic for Special Children, Mount Eaton, OH 44659, USA
| | - Helen Stewart
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Trust, Oxford OX3 7HE, UK
| | - Andrew Y Shuen
- London Health Sciences Centre, London, ON N6A 5W9, Canada
- Division of Medical Genetics, Department of Pediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5W9, Canada
| | - John Schreiber
- Department of Neurology, Children’s National Medical Center, Washington DC 20007, USA
| | - Liz Tuck
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - James Tonks
- Haven Clinical Psychology Practice Ltd, Bude, Cornwall EX23 9HP, UK
| | - Thorkild Terkelsen
- Department of Clinical Genetics, Aarhus University Hospital, Aarhus DK-8200, Denmark
| | - Conny van Ravenswaaij-Arts
- Department of Genetics, University Medical Centre, University of Groningen, Groningen 9713 GZ, The Netherlands
| | - Pradeep Vasudevan
- Department of Clinical Genetics, University Hospitals of Leicester, Leicester Royal Infirmary, Leicester LE1 7RH, UK
| | - Olivia Wenger
- New Leaf Center, Clinic for Special Children, Mount Eaton, OH 44659, USA
| | - Michael Wright
- Institute of Human Genetics, International Centre for Life, Newcastle upon Tyne NE1 7RU, UK
| | - Andrew Day
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Qkine Ltd., Cambridge CB5 8HW, UK
| | - Adam Hunter
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Minal Patel
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Christopher J Lelliott
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Institute of Metabolic Science, Cambridge University, Cambridge CB2 0QQ, UK
| | - Peter B Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Binnaz Yalcin
- INSERM Unit 1231, Université de Bourgogne Franche-Comté, Dijon 21078, France
| | - Andrew H Crosby
- RILD Wellcome Wolfson Medical Research Centre, University of Exeter, Exeter EX2 5DW, UK
| | - Emma L Baple
- RILD Wellcome Wolfson Medical Research Centre, University of Exeter, Exeter EX2 5DW, UK
- Peninsula Clinical Genetics Service, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX1 2ED, UK
| | - Darren W Logan
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Waltham Petcare Science Institute, Waltham on the Wolds LE14 4RT, UK
| | - Matthew E Hurles
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Sebastian S Gerety
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
- Open Targets, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
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4
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Developing Novel Experimental Models of m-TORopathic Epilepsy and Related Neuropathologies: Translational Insights from Zebrafish. Int J Mol Sci 2023; 24:ijms24021530. [PMID: 36675042 PMCID: PMC9866103 DOI: 10.3390/ijms24021530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 01/15/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an important molecular regulator of cell growth and proliferation. Brain mTOR activity plays a crucial role in synaptic plasticity, cell development, migration and proliferation, as well as memory storage, protein synthesis, autophagy, ion channel expression and axonal regeneration. Aberrant mTOR signaling causes a diverse group of neurological disorders, termed 'mTORopathies'. Typically arising from mutations within the mTOR signaling pathway, these disorders are characterized by cortical malformations and other neuromorphological abnormalities that usually co-occur with severe, often treatment-resistant, epilepsy. Here, we discuss recent advances and current challenges in developing experimental models of mTOR-dependent epilepsy and other related mTORopathies, including using zebrafish models for studying these disorders, as well as outline future directions of research in this field.
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5
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Human In Vitro Models of Epilepsy Using Embryonic and Induced Pluripotent Stem Cells. Cells 2022; 11:cells11243957. [PMID: 36552721 PMCID: PMC9776452 DOI: 10.3390/cells11243957] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/25/2022] [Accepted: 12/04/2022] [Indexed: 12/14/2022] Open
Abstract
The challenges in making animal models of complex human epilepsy phenotypes with varied aetiology highlights the need to develop alternative disease models that can address the limitations of animal models by effectively recapitulating human pathophysiology. The advances in stem cell technology provide an opportunity to use human iPSCs to make disease-in-a-dish models. The focus of this review is to report the current information and progress in the generation of epileptic patient-specific iPSCs lines, isogenic control cell lines, and neuronal models. These in vitro models can be used to study the underlying pathological mechanisms of epilepsies, anti-seizure medication resistance, and can also be used for drug testing and drug screening with their isogenic control cell lines.
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6
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Nguyen LH, Bordey A. Current Review in Basic Science: Animal Models of Focal Cortical Dysplasia and Epilepsy. Epilepsy Curr 2022; 22:234-240. [PMID: 36187145 PMCID: PMC9483763 DOI: 10.1177/15357597221098230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Focal cortical dysplasia (FCD) is a malformation of cortical development that is a prevalent cause of intractable epilepsy in children. Of the three FCD subtypes, understanding the etiology and pathogenesis of FCD type II has seen the most progress owing to the recent advances in identifying gene mutations along the mTOR signaling pathway as a frequent cause of this disorder. Accordingly, numerous animal models of FCD type II based on genetic manipulation of the mTOR signaling pathway have emerged to investigate the mechanisms of epileptogenesis and novel therapeutics for epilepsy. These include transgenic and in utero electroporation-based animal models. Here, we review the histopathological and electroclinical features of existing FCD type II animal models and discuss the scientific and technical considerations, clinical applications, and limitations of current models. We also highlight other models of FCD based on early life acquired factors.
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Affiliation(s)
- Lena H. Nguyen
- Departments of Neurosurgery and Cellular & Molecular
Physiology, Yale University School of
Medicine, New Haven, CT, USA
| | - Angélique Bordey
- Departments of Neurosurgery and Cellular & Molecular
Physiology, Yale University School of
Medicine, New Haven, CT, USA
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7
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Girodengo M, Ultanir SK, Bateman JM. Mechanistic target of rapamycin signaling in human nervous system development and disease. Front Mol Neurosci 2022; 15:1005631. [PMID: 36226315 PMCID: PMC9549271 DOI: 10.3389/fnmol.2022.1005631] [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: 07/28/2022] [Accepted: 09/06/2022] [Indexed: 11/30/2022] Open
Abstract
Mechanistic target of rapamycin (mTOR) is a highly conserved serine/threonine kinase that regulates fundamental cellular processes including growth control, autophagy and metabolism. mTOR has key functions in nervous system development and mis-regulation of mTOR signaling causes aberrant neurodevelopment and neurological diseases, collectively called mTORopathies. In this mini review we discuss recent studies that have deepened our understanding of the key roles of the mTOR pathway in human nervous system development and disease. Recent advances in single-cell transcriptomics have been exploited to reveal specific roles for mTOR signaling in human cortical development that may have contributed to the evolutionary divergence from our primate ancestors. Cerebral organoid technology has been utilized to show that mTOR signaling is active in and regulates outer radial glial cells (RGCs), a population of neural stem cells that distinguish the human developing cortex. mTOR signaling has a well-established role in hamartoma syndromes such as tuberous sclerosis complex (TSC) and other mTORopathies. New ultra-sensitive techniques for identification of somatic mTOR pathway mutations have shed light on the neurodevelopmental origin and phenotypic heterogeneity seen in mTORopathy patients. These emerging studies suggest that mTOR signaling may facilitate developmental processes specific to human cortical development but also, when mis-regulated, cause cortical malformations and neurological disease.
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Affiliation(s)
- Marie Girodengo
- Kinases and Brain Development Lab, The Francis Crick Institute, London, United Kingdom.,King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
| | - Sila K Ultanir
- Kinases and Brain Development Lab, The Francis Crick Institute, London, United Kingdom
| | - Joseph M Bateman
- King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
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8
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Karalis V, Bateup HS. Current Approaches and Future Directions for the Treatment of mTORopathies. Dev Neurosci 2021; 43:143-158. [PMID: 33910214 PMCID: PMC8440338 DOI: 10.1159/000515672] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/13/2021] [Indexed: 11/19/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a kinase at the center of an evolutionarily conserved signaling pathway that orchestrates cell growth and metabolism. mTOR responds to an array of intra- and extracellular stimuli and in turn controls multiple cellular anabolic and catabolic processes. Aberrant mTOR activity is associated with numerous diseases, with particularly profound impact on the nervous system. mTOR is found in two protein complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which are governed by different upstream regulators and have distinct cellular actions. Mutations in genes encoding for mTOR regulators result in a collection of neurodevelopmental disorders known as mTORopathies. While these disorders can affect multiple organs, neuropsychiatric conditions such as epilepsy, intellectual disability, and autism spectrum disorder have a major impact on quality of life. The neuropsychiatric aspects of mTORopathies have been particularly challenging to treat in a clinical setting. Current therapeutic approaches center on rapamycin and its analogs, drugs that are administered systemically to inhibit mTOR activity. While these drugs show some clinical efficacy, adverse side effects, incomplete suppression of mTOR targets, and lack of specificity for mTORC1 or mTORC2 may limit their utility. An increased understanding of the neurobiology of mTOR and the underlying molecular, cellular, and circuit mechanisms of mTOR-related disorders will facilitate the development of improved therapeutics. Animal models of mTORopathies have helped unravel the consequences of mTOR pathway mutations in specific brain cell types and developmental stages, revealing an array of disease-related phenotypes. In this review, we discuss current progress and potential future directions for the therapeutic treatment of mTORopathies with a focus on findings from genetic mouse models.
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Affiliation(s)
- Vasiliki Karalis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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9
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Dang LT, Vaid S, Lin G, Swaminathan P, Safran J, Loughman A, Lee M, Glenn T, Majolo F, Crino PB, Parent JM. STRADA-mutant human cortical organoids model megalencephaly and exhibit delayed neuronal differentiation. Dev Neurobiol 2021; 81:696-709. [PMID: 33619909 DOI: 10.1002/dneu.22816] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 12/31/2022]
Abstract
Genetic diseases involving overactivation of the mechanistic target of rapamycin (mTOR) pathway, so-called "mTORopathies," often manifest with malformations of cortical development (MCDs), epilepsy, and cognitive impairment. How mTOR pathway hyperactivation results in abnormal human cortical development is poorly understood. To study the effect of mTOR hyperactivity on early stages of cortical development, we focused on Pretzel Syndrome (polyhydramnios, megalencephaly, symptomatic epilepsy; PMSE syndrome), a rare mTORopathy caused by homozygous germline mutations in the STRADA gene. We developed a human cortical organoid (hCO) model of PMSE and examined morphology and size for the first 2 weeks of organoid growth, and cell type composition at weeks 2, 8, and 12 of differentiation. In the second week, PMSE hCOs enlarged more rapidly than controls and displayed an abnormal Wnt pathway-dependent increase in neural rosette structures. PMSE hCOs also exhibited delayed neurogenesis, decreased subventricular zone progenitors, increased proliferation and cell death, and an abnormal architecture of primary cilia. At week 8, PMSE hCOs had fewer deep layer neurons. By week 12, neurogenesis recovered in PMSE organoids, but they displayed increased outer radial glia, a cell type thought to contribute to the expansion of the human cerebral cortex. Together, these findings suggest that megalencephaly in PMSE arises from the expansion of neural stem cells in early corticogenesis and potentially also from increased outer radial glial at later gestational stages. The delayed neuronal differentiation in PMSE organoids demonstrates the important role the mTOR pathway plays in the maintenance and expansion of the stem cell pool.
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Affiliation(s)
- Louis T Dang
- Department of Pediatrics, Michigan Medicine, Ann Arbor, MI, USA.,Department of Neurology, Michigan Medicine, Ann Arbor, MI, USA.,Michigan Neuroscience Institute, Michigan Medicine, Ann Arbor, MI, USA
| | - Shivanshi Vaid
- Department of Pediatrics, Michigan Medicine, Ann Arbor, MI, USA.,Michigan Neuroscience Institute, Michigan Medicine, Ann Arbor, MI, USA
| | - Grace Lin
- Department of Neurology, Michigan Medicine, Ann Arbor, MI, USA.,Michigan Neuroscience Institute, Michigan Medicine, Ann Arbor, MI, USA
| | | | - Jordan Safran
- Department of Pediatrics, Michigan Medicine, Ann Arbor, MI, USA
| | - Anna Loughman
- Department of Pediatrics, Michigan Medicine, Ann Arbor, MI, USA
| | - Monica Lee
- Department of Pediatrics, Michigan Medicine, Ann Arbor, MI, USA
| | - Trevor Glenn
- Department of Neurology, Michigan Medicine, Ann Arbor, MI, USA
| | - Fernanda Majolo
- Department of Neurology, Michigan Medicine, Ann Arbor, MI, USA
| | - Peter B Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jack M Parent
- Department of Neurology, Michigan Medicine, Ann Arbor, MI, USA.,Michigan Neuroscience Institute, Michigan Medicine, Ann Arbor, MI, USA.,Neurology Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA
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10
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Nguyen LH, Bordey A. Convergent and Divergent Mechanisms of Epileptogenesis in mTORopathies. Front Neuroanat 2021; 15:664695. [PMID: 33897381 PMCID: PMC8064518 DOI: 10.3389/fnana.2021.664695] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/17/2021] [Indexed: 12/30/2022] Open
Abstract
Hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) due to mutations in genes along the PI3K-mTOR pathway and the GATOR1 complex causes a spectrum of neurodevelopmental disorders (termed mTORopathies) associated with malformation of cortical development and intractable epilepsy. Despite these gene variants’ converging impact on mTORC1 activity, emerging findings suggest that these variants contribute to epilepsy through both mTORC1-dependent and -independent mechanisms. Here, we review the literature on in utero electroporation-based animal models of mTORopathies, which recapitulate the brain mosaic pattern of mTORC1 hyperactivity, and compare the effects of distinct PI3K-mTOR pathway and GATOR1 complex gene variants on cortical development and epilepsy. We report the outcomes on cortical pyramidal neuronal placement, morphology, and electrophysiological phenotypes, and discuss some of the converging and diverging mechanisms responsible for these alterations and their contribution to epileptogenesis. We also discuss potential therapeutic strategies for epilepsy, beyond mTORC1 inhibition with rapamycin or everolimus, that could offer personalized medicine based on the gene variant.
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Affiliation(s)
- Lena H Nguyen
- Department of Neurosurgery, Yale School of Medicine, Yale University, New Haven, CT, United States.,Department of Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Angélique Bordey
- Department of Neurosurgery, Yale School of Medicine, Yale University, New Haven, CT, United States.,Department of Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT, United States
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