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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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Medina Lemus A, Boelman C, Myers KA. Epilepsy in Legius syndrome: Coincidence or causation? Am J Med Genet A 2024; 194:e63547. [PMID: 38268057 DOI: 10.1002/ajmg.a.63547] [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: 11/03/2023] [Revised: 01/10/2024] [Accepted: 01/13/2024] [Indexed: 01/26/2024]
Abstract
Legius syndrome is a rare genetic disorder, caused by heterozygous SPRED1 pathogenic variants, which shares phenotypic features with neurofibromatosis type 1 (NF1). Both conditions typically involve café-au-lait macules, axillary freckling, and macrocephaly; however, patients with NF1 are also at risk for tumors, such as optic nerve gliomas and neurofibromas. Seizure risk is known to be elevated in NF1, but there has been little study of this aspect of Legius syndrome. The reported epilepsy incidence is 3.3%-5%, well above the general population incidence of ~0.5%-1%, but the few reports in the literature have very little data regarding epilepsy phenotype. We identified two unrelated individuals, both with Legius syndrome and epilepsy, and performed thorough phenotyping. One individual's mother also had Legius syndrome and now-resolved childhood epilepsy, as well as reports of more distant relatives who also had multiple café-au-lait macules and seizures. Both probands had experienced childhood-onset focal seizures, with normal brain MRI. In one patient, EEG later showed apparently generalized epileptiform abnormalities. Based on the data from this small case series and literature review, seizure risk is increased in people with Legius syndrome, but the epilepsy prognosis appears to be generally good, with patients having either self-limited or pharmacoresponsive courses.
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Affiliation(s)
- Adalbeis Medina Lemus
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
| | - Cyrus Boelman
- Division of Neurology, Department of Pediatrics, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | - Kenneth A Myers
- Division of Neurology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
- Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- Department of Neurology and Neurosurgery, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
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3
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Nguyen LH, Xu Y, Nair M, Bordey A. The mTOR pathway genes MTOR, Rheb, Depdc5, Pten, and Tsc1 have convergent and divergent impacts on cortical neuron development and function. eLife 2024; 12:RP91010. [PMID: 38411613 PMCID: PMC10942629 DOI: 10.7554/elife.91010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024] Open
Abstract
Brain somatic mutations in various components of the mTOR complex 1 (mTORC1) pathway have emerged as major causes of focal malformations of cortical development and intractable epilepsy. While these distinct gene mutations converge on excessive mTORC1 signaling and lead to common clinical manifestations, it remains unclear whether they cause similar cellular and synaptic disruptions underlying cortical network hyperexcitability. Here, we show that in utero activation of the mTORC1 activator genes, Rheb or MTOR, or biallelic inactivation of the mTORC1 repressor genes, Depdc5, Tsc1, or Pten in the mouse medial prefrontal cortex leads to shared alterations in pyramidal neuron morphology, positioning, and membrane excitability but different changes in excitatory synaptic transmission. Our findings suggest that, despite converging on mTORC1 signaling, mutations in different mTORC1 pathway genes differentially impact cortical excitatory synaptic activity, which may confer gene-specific mechanisms of hyperexcitability and responses to therapeutic intervention.
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Affiliation(s)
- Lena H Nguyen
- Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at DallasRichardsonUnited States
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Youfen Xu
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Maanasi Nair
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Angelique Bordey
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
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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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Sokolov AM, Aurich M, Bordey A. In Utero Electroporated Neurons for Medium-Throughput Screening of Compounds Regulating Neuron Morphology. eNeuro 2023; 10:ENEURO.0160-23.2023. [PMID: 37620147 PMCID: PMC10464655 DOI: 10.1523/eneuro.0160-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/27/2023] [Accepted: 07/27/2023] [Indexed: 08/26/2023] Open
Abstract
Several neurodevelopmental disorders are associated with increased mTOR activity that results in pathogenic neuronal dysmorphogenesis (i.e., soma and dendrite overgrowth), leading to circuit alterations associated with epilepsy and neurologic disabilities. Although an mTOR analog is approved for the treatment of epilepsy in one of these disorders, it has limited efficacy and is associated with a wide range of side effects. There is a need to develop novel agents for the treatment of mTOR-pathway related disorders. Here, we developed a medium-throughput phenotypic assay to test drug efficacy on neurite morphogenesis of mouse neurons in a hyperactive mTOR condition. Our assay involved in utero electroporation (IUE) of a selective population of cortical pyramidal neurons with a plasmid encoding the constitutively active mTOR activator, Rheb, and tdTomato. Labeled neurons from the somatosensory cortex (SSC) were cultured onto 96-well plates and fixed at various days in vitro or following Torin 1 treatment. Automated systems were used for image acquisition and neuron morphologic measurements. We validated our automated approach using traditional manual methods of neuron morphologic assessment. Both automated and manual analyses showed increased neurite length and complexity over time, and decreased neurite overgrowth and soma size with Torin 1. These data validate the accuracy of our automated approach that takes hours compared with weeks when using traditional manual methods. Taken together, this assay can be scaled to screen 32 compounds simultaneously in two weeks, highlighting its robustness and efficiency for medium-throughput screening of candidate therapeutics on a defined population of wild-type or diseased neurons.
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Affiliation(s)
- Aidan M Sokolov
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Wu Tsai Institute, Yale University School of Medicine, New Haven, CT 06520-8082
| | - Mariana Aurich
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Wu Tsai Institute, Yale University School of Medicine, New Haven, CT 06520-8082
| | - Angélique Bordey
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Wu Tsai Institute, Yale University School of Medicine, New Haven, CT 06520-8082
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Lee WS, Macdonald-Laurs E, Stephenson S, D'Arcy C, Maixner W, Harvey AS, Lockhart PJ, Leventer RJ. Pathogenic RHEB Somatic Variant in a Child With Tuberous Sclerosis Complex Without Pathogenic Variants in TSC1 or TSC2. Neurology 2023; 101:78-82. [PMID: 37015817 PMCID: PMC10351555 DOI: 10.1212/wnl.0000000000207177] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 01/26/2023] [Indexed: 04/06/2023] Open
Abstract
OBJECTIVE To describe a child meeting diagnostic criteria for tuberous sclerosis complex (TSC) carrying a pathogenic somatic variant in RHEB, but no pathogenic variants in the 2 known TSC genes, TSC1 or TSC2. METHODS We present the clinical and imaging findings in a child presenting with drug-resistant focal seizures and multiple cortical tubers, a subependymal giant cell astrocytoma and multiple subependymal nodules in 1 cerebral hemisphere. Targeted panel sequencing and exome sequencing were performed on genomic DNA derived from blood and resected tuber tissue. RESULTS The child satisfied clinical diagnostic criteria for TSC, having 3 major features, only 2 of which are required for diagnosis. Genetic testing did not identify pathogenic variants or copy number variations in TSC1 or TSC2 but identified a pathogenic somatic RHEB variant (NM_005614.4:c.104_105delACinsTA [p.Tyr35Leu]) in the cortical tuber. DISCUSSION RHEB is a partner of the TSC1/2 complex in the mechanistic target of rapamycin pathway. Somatic variants in RHEB are associated with focal cortical dysplasia and hemimegalencephaly. We propose that variants in RHEB may explain some of the genetically undiagnosed TSC cases and may be the third gene for TSC, or TSC3.
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Affiliation(s)
- Wei Shern Lee
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - Emma Macdonald-Laurs
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - Sarah Stephenson
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - Colleen D'Arcy
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - Wirginia Maixner
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - A Simon Harvey
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - Paul J Lockhart
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia
| | - Richard J Leventer
- From the Bruce Lefroy Centre, Murdoch Children's Research Institute (W.S.L., S.S., P.J.L.); Department of Paediatrics (W.S.L., E.M-L., S.S., W.M., A.S.H., P.J.L., R.J.L.), The University of Melbourne; Department of Neurology (E.M-L., A.S.H., R.J.L.), The Royal Children's Hospital; Department of Anatomical Pathology (C.D.A.), The Royal Children's Hospital; Department of Neurosurgery (W.M.), The Royal Children's Hospital, Parkville, Australia.
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Boßelmann CM, Leu C, Lal D. Technological and computational approaches to detect somatic mosaicism in epilepsy. Neurobiol Dis 2023:106208. [PMID: 37343892 DOI: 10.1016/j.nbd.2023.106208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 06/03/2023] [Accepted: 06/16/2023] [Indexed: 06/23/2023] Open
Abstract
Lesional epilepsy is a common and severe disease commonly associated with malformations of cortical development, including focal cortical dysplasia and hemimegalencephaly. Recent advances in sequencing and variant calling technologies have identified several genetic causes, including both short/single nucleotide and structural somatic variation. In this review, we aim to provide a comprehensive overview of the methodological advancements in this field while highlighting the unresolved technological and computational challenges that persist, including ultra-low variant allele fractions in bulk tissue, low availability of paired control samples, spatial variability of mutational burden within the lesion, and the issue of false-positive calls and validation procedures. Information from genetic testing in focal epilepsy may be integrated into clinical care to inform histopathological diagnosis, postoperative prognosis, and candidate precision therapies.
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Affiliation(s)
- Christian M Boßelmann
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Costin Leu
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK.
| | - Dennis Lal
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA; Stanley Center for Psychiatric Research, Broad Institute of Harvard and M.I.T., Cambridge, MA, USA; Cologne Center for Genomics (CCG), University of Cologne, Cologne, DE, USA
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Gerasimenko A, Baldassari S, Baulac S. mTOR pathway: Insights into an established pathway for brain mosaicism in epilepsy. Neurobiol Dis 2023; 182:106144. [PMID: 37149062 DOI: 10.1016/j.nbd.2023.106144] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/08/2023] Open
Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway is an essential regulator of numerous cellular activities such as metabolism, growth, proliferation, and survival. The mTOR cascade recently emerged as a critical player in the pathogenesis of focal epilepsies and cortical malformations. The 'mTORopathies' comprise a spectrum of cortical malformations that range from whole brain (megalencephaly) and hemispheric (hemimegalencephaly) abnormalities to focal abnormalities, such as focal cortical dysplasia type II (FCDII), which manifest with drug-resistant epilepsies. The spectrum of cortical dysplasia results from somatic brain mutations in the mTOR pathway activators AKT3, MTOR, PIK3CA, and RHEB and from germline and somatic mutations in mTOR pathway repressors, DEPDC5, NPRL2, NPRL3, TSC1 and TSC2. The mTORopathies are characterized by excessive mTOR pathway activation, leading to a broad range of structural and functional impairments. Here, we provide a comprehensive literature review of somatic mTOR-activating mutations linked to epilepsy and cortical malformations in 292 patients and discuss the perspectives of targeted therapeutics for personalized medicine.
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Affiliation(s)
- Anna Gerasimenko
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, 75013 Paris, France; APHP Sorbonne Université, GH Pitié Salpêtrière et Trousseau, Département de Génétique, Centre de référence "déficiences intellectuelles de causes rares", Paris, France
| | - Sara Baldassari
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, 75013 Paris, France
| | - Stéphanie Baulac
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, 75013 Paris, France.
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9
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De Meulemeester AS, Heylen L, Siekierska A, Mills JD, Romagnolo A, Van Der Wel NN, Aronica E, de Witte PAM. Hyperactivation of mTORC1 in a double hit mutant zebrafish model of tuberous sclerosis complex causes increased seizure susceptibility and neurodevelopmental abnormalities. Front Cell Dev Biol 2022; 10:952832. [PMID: 36238691 PMCID: PMC9552079 DOI: 10.3389/fcell.2022.952832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/05/2022] [Indexed: 11/16/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is a multisystem genetic disorder caused by pathogenic variants in TSC1 and TSC2 genes. TSC patients present with seizures and brain abnormalities such as tubers and subependymal giant cells astrocytoma (SEGA). Despite common molecular and clinical features, the severity of the disease varies greatly, even intrafamilially. The second hit hypothesis suggests that an additional, inactivating mutation in the remaining functional allele causes a more severe phenotype and therefore explains the phenotypic variability. Recently, second hit mutations have been detected frequently in mTORopathies. To investigate the pathophysiological effects of second hit mutations, several mouse models have been developed. Here, we opted for a double mutant zebrafish model that carries a LOF mutation both in the tsc2 and the depdc5 gene. To the best of our knowledge, this is the first time a second-hit model has been studied in zebrafish. Significantly, the DEP domain-containing protein 5 (DEPDC5) gene has an important role in the regulation of mTORC1, and the combination of a germline TSC2 and somatic DEPDC5 mutation has been described in a TSC patient with intractable epilepsy. Our depdc5−/−x tsc2−/− double mutant zebrafish line displayed greatly increased levels of mammalian target of rapamycin (mTORC1) activity, augmented seizure susceptibility, and early lethality which could be rescued by rapamycin. Histological analysis of the brain revealed ventricular dilatation in the tsc2 and double homozygotes. RNA-sequencing showed a linear relation between the number of differentially expressed genes (DEGs) and the degree of mTORC1 hyperactivity. Enrichment analysis of their transcriptomes revealed that many genes associated with neurological developmental processes were downregulated and mitochondrial genes were upregulated. In particular, the transcriptome of human SEGA lesions overlapped strongly with the double homozygous zebrafish larvae. The data highlight the clinical relevance of the depdc5−/− x tsc2−/− double mutant zebrafish larvae that showed a more severe phenotype compared to the single mutants. Finally, analysis of gene-drug interactions identified interesting pharmacological targets for SEGA, underscoring the value of our small zebrafish vertebrate model for future drug discovery efforts.
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Affiliation(s)
| | - Lise Heylen
- Laboratory for Molecular Biodiscovery, KU Leuven, Leuven, Belgium
| | | | - James D. Mills
- Department of (Neuro)Pathology Amsterdam Neuroscience, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, United Kingdom
- Chalfont Centre for Epilepsy, Chalfont St Peter, United Kingdom
| | - Alessia Romagnolo
- Department of (Neuro)Pathology Amsterdam Neuroscience, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
| | - Nicole N. Van Der Wel
- Department of Medical Biology, Electron Microscopy Center Amsterdam, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology Amsterdam Neuroscience, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
- Stichting Epilepsie Instelling Nederland (SEIN), Heemstede, Netherlands
| | - Peter A. M. de Witte
- Laboratory for Molecular Biodiscovery, KU Leuven, Leuven, Belgium
- *Correspondence: Peter A. M. de Witte,
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10
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Lai D, Gade M, Yang E, Koh HY, Lu J, Walley NM, Buckley AF, Sands TT, Akman CI, Mikati MA, McKhann GM, Goldman JE, Canoll P, Alexander AL, Park KL, Von Allmen GK, Rodziyevska O, Bhattacharjee MB, Lidov HGW, Vogel H, Grant GA, Porter BE, Poduri AH, Crino PB, Heinzen EL. Somatic variants in diverse genes leads to a spectrum of focal cortical malformations. Brain 2022; 145:2704-2720. [PMID: 35441233 PMCID: PMC9612793 DOI: 10.1093/brain/awac117] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/19/2022] [Accepted: 03/13/2022] [Indexed: 11/14/2022] Open
Abstract
Post-zygotically acquired genetic variants, or somatic variants, that arise during cortical development have emerged as important causes of focal epilepsies, particularly those due to malformations of cortical development. Pathogenic somatic variants have been identified in many genes within the PI3K-AKT-mTOR-signalling pathway in individuals with hemimegalencephaly and focal cortical dysplasia (type II), and more recently in SLC35A2 in individuals with focal cortical dysplasia (type I) or non-dysplastic epileptic cortex. Given the expanding role of somatic variants across different brain malformations, we sought to delineate the landscape of somatic variants in a large cohort of patients who underwent epilepsy surgery with hemimegalencephaly or focal cortical dysplasia. We evaluated samples from 123 children with hemimegalencephaly (n = 16), focal cortical dysplasia type I and related phenotypes (n = 48), focal cortical dysplasia type II (n = 44), or focal cortical dysplasia type III (n = 15). We performed high-depth exome sequencing in brain tissue-derived DNA from each case and identified somatic single nucleotide, indel and large copy number variants. In 75% of individuals with hemimegalencephaly and 29% with focal cortical dysplasia type II, we identified pathogenic variants in PI3K-AKT-mTOR pathway genes. Four of 48 cases with focal cortical dysplasia type I (8%) had a likely pathogenic variant in SLC35A2. While no other gene had multiple disease-causing somatic variants across the focal cortical dysplasia type I cohort, four individuals in this group had a single pathogenic or likely pathogenic somatic variant in CASK, KRAS, NF1 and NIPBL, genes previously associated with neurodevelopmental disorders. No rare pathogenic or likely pathogenic somatic variants in any neurological disease genes like those identified in the focal cortical dysplasia type I cohort were found in 63 neurologically normal controls (P = 0.017), suggesting a role for these novel variants. We also identified a somatic loss-of-function variant in the known epilepsy gene, PCDH19, present in a small number of alleles in the dysplastic tissue from a female patient with focal cortical dysplasia IIIa with hippocampal sclerosis. In contrast to focal cortical dysplasia type II, neither focal cortical dysplasia type I nor III had somatic variants in genes that converge on a unifying biological pathway, suggesting greater genetic heterogeneity compared to type II. Importantly, we demonstrate that focal cortical dysplasia types I, II and III are associated with somatic gene variants across a broad range of genes, many associated with epilepsy in clinical syndromes caused by germline variants, as well as including some not previously associated with radiographically evident cortical brain malformations.
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Affiliation(s)
- Dulcie Lai
- Division of Pharmacology and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Meethila Gade
- Division of Pharmacology and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Edward Yang
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hyun Yong Koh
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA.,Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Jinfeng Lu
- Division of Pharmacology and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nicole M Walley
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Anne F Buckley
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
| | - Tristan T Sands
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA.,Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
| | - Cigdem I Akman
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
| | - Mohamad A Mikati
- Department of Neurobiology, Duke University, Durham, NC 27708, USA.,Division of Pediatric Neurology, Duke University Medical Center, Durham, NC 27710, USA
| | - Guy M McKhann
- Department of Neurosurgery, Columbia University, New York Presbyterian Hospital, New York, NY 10032, USA
| | - James E Goldman
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Peter Canoll
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Allyson L Alexander
- Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kristen L Park
- Department of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Gretchen K Von Allmen
- Department of Neurology, McGovern Medical School, Houston, TX 77030, USA.,Division of Child Neurology, Department of Pediatrics, McGovern Medical School, Houston, TX 77030, USA
| | - Olga Rodziyevska
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School, Houston, TX 77030, USA
| | | | - Hart G W Lidov
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hannes Vogel
- Department of Pathology, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Gerald A Grant
- Department of Neurosurgery, Lucile Packard Children's Hospital at Stanford, School of Medicine, Stanford, CA 94305, USA
| | - Brenda E Porter
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Annapurna H Poduri
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA.,Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Peter B Crino
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Erin L Heinzen
- Division of Pharmacology and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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11
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Fasano G, Compagnucci C, Dallapiccola B, Tartaglia M, Lauri A. Teleost Fish and Organoids: Alternative Windows Into the Development of Healthy and Diseased Brains. Front Mol Neurosci 2022; 15:855786. [PMID: 36034498 PMCID: PMC9403253 DOI: 10.3389/fnmol.2022.855786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
The variety in the display of animals’ cognition, emotions, and behaviors, typical of humans, has its roots within the anterior-most part of the brain: the forebrain, giving rise to the neocortex in mammals. Our understanding of cellular and molecular events instructing the development of this domain and its multiple adaptations within the vertebrate lineage has progressed in the last decade. Expanding and detailing the available knowledge on regionalization, progenitors’ behavior and functional sophistication of the forebrain derivatives is also key to generating informative models to improve our characterization of heterogeneous and mechanistically unexplored cortical malformations. Classical and emerging mammalian models are irreplaceable to accurately elucidate mechanisms of stem cells expansion and impairments of cortex development. Nevertheless, alternative systems, allowing a considerable reduction of the burden associated with animal experimentation, are gaining popularity to dissect basic strategies of neural stem cells biology and morphogenesis in health and disease and to speed up preclinical drug testing. Teleost vertebrates such as zebrafish, showing conserved core programs of forebrain development, together with patients-derived in vitro 2D and 3D models, recapitulating more accurately human neurogenesis, are now accepted within translational workflows spanning from genetic analysis to functional investigation. Here, we review the current knowledge of common and divergent mechanisms shaping the forebrain in vertebrates, and causing cortical malformations in humans. We next address the utility, benefits and limitations of whole-brain/organism-based fish models or neuronal ensembles in vitro for translational research to unravel key genes and pathological mechanisms involved in neurodevelopmental diseases.
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12
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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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13
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Cortical Dysplasia and the mTOR Pathway: How the Study of Human Brain Tissue Has Led to Insights into Epileptogenesis. Int J Mol Sci 2022; 23:ijms23031344. [PMID: 35163267 PMCID: PMC8835853 DOI: 10.3390/ijms23031344] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 02/01/2023] Open
Abstract
Type II focal cortical dysplasia (FCD) is a neuropathological entity characterised by cortical dyslamination with the presence of dysmorphic neurons only (FCDIIA) or the presence of both dysmorphic neurons and balloon cells (FCDIIB). The year 2021 marks the 50th anniversary of the recognition of FCD as a cause of drug resistant epilepsy, and it is now the most common reason for epilepsy surgery. The causes of FCD remained unknown until relatively recently. The study of resected human FCD tissue using novel genomic technologies has led to remarkable advances in understanding the genetic basis of FCD. Mechanistic parallels have emerged between these non-neoplastic lesions and neoplastic disorders of cell growth and differentiation, especially through perturbations of the mammalian target of rapamycin (mTOR) signalling pathway. This narrative review presents the advances through which the aetiology of FCDII has been elucidated in chronological order, from recognition of an association between FCD and the mTOR pathway to the identification of somatic mosaicism within FCD tissue. We discuss the role of a two-hit mechanism, highlight current challenges and future directions in detecting somatic mosaicism in brain and discuss how knowledge of FCD may inform novel precision treatments of these focal epileptogenic malformations of human cortical development.
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14
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Deb BK, Bateup HS. Modeling Somatic Mutations Associated With Neurodevelopmental Disorders in Human Brain Organoids. Front Mol Neurosci 2022; 14:787243. [PMID: 35058746 PMCID: PMC8764387 DOI: 10.3389/fnmol.2021.787243] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) are a collection of diseases with early life onset that often present with developmental delay, cognitive deficits, and behavioral conditions. In some cases, severe outcomes such as brain malformations and intractable epilepsy can occur. The mutations underlying NDDs may be inherited or de novo, can be gain- or loss-of-function, and can affect one or more genes. Recent evidence indicates that brain somatic mutations contribute to several NDDs, in particular malformations of cortical development. While advances in sequencing technologies have enabled the detection of these somatic mutations, the mechanisms by which they alter brain development and function are not well understood due to limited model systems that recapitulate these events. Human brain organoids have emerged as powerful models to study the early developmental events of the human brain. Brain organoids capture the developmental progression of the human brain and contain human-enriched progenitor cell types. Advances in human stem cell and genome engineering provide an opportunity to model NDD-associated somatic mutations in brain organoids. These organoids can be tracked throughout development to understand the impact of somatic mutations on early human brain development and function. In this review, we discuss recent evidence that somatic mutations occur in the developing human brain, that they can lead to NDDs, and discuss how they could be modeled using human brain organoids.
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Affiliation(s)
- Bipan K. Deb
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Helen S. Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
- Chan Zuckerberg Biohub, San Francisco, CA, United States
- *Correspondence: Helen S. Bateup
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15
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Moloney PB, Cavalleri GL, Delanty N. Epilepsy in the mTORopathies: opportunities for precision medicine. Brain Commun 2021; 3:fcab222. [PMID: 34632383 PMCID: PMC8495134 DOI: 10.1093/braincomms/fcab222] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/23/2021] [Accepted: 08/30/2021] [Indexed: 01/16/2023] Open
Abstract
The mechanistic target of rapamycin signalling pathway serves as a ubiquitous regulator of cell metabolism, growth, proliferation and survival. The main cellular activity of the mechanistic target of rapamycin cascade funnels through mechanistic target of rapamycin complex 1, which is inhibited by rapamycin, a macrolide compound produced by the bacterium Streptomyces hygroscopicus. Pathogenic variants in genes encoding upstream regulators of mechanistic target of rapamycin complex 1 cause epilepsies and neurodevelopmental disorders. Tuberous sclerosis complex is a multisystem disorder caused by mutations in mechanistic target of rapamycin regulators TSC1 or TSC2, with prominent neurological manifestations including epilepsy, focal cortical dysplasia and neuropsychiatric disorders. Focal cortical dysplasia type II results from somatic brain mutations in mechanistic target of rapamycin pathway activators MTOR, AKT3, PIK3CA and RHEB and is a major cause of drug-resistant epilepsy. DEPDC5, NPRL2 and NPRL3 code for subunits of the GTPase-activating protein (GAP) activity towards Rags 1 complex (GATOR1), the principal amino acid-sensing regulator of mechanistic target of rapamycin complex 1. Germline pathogenic variants in GATOR1 genes cause non-lesional focal epilepsies and epilepsies associated with malformations of cortical development. Collectively, the mTORopathies are characterized by excessive mechanistic target of rapamycin pathway activation and drug-resistant epilepsy. In the first large-scale precision medicine trial in a genetically mediated epilepsy, everolimus (a synthetic analogue of rapamycin) was effective at reducing seizure frequency in people with tuberous sclerosis complex. Rapamycin reduced seizures in rodent models of DEPDC5-related epilepsy and focal cortical dysplasia type II. This review outlines a personalized medicine approach to the management of epilepsies in the mTORopathies. We advocate for early diagnostic sequencing of mechanistic target of rapamycin pathway genes in drug-resistant epilepsy, as identification of a pathogenic variant may point to an occult dysplasia in apparently non-lesional epilepsy or may uncover important prognostic information including, an increased risk of sudden unexpected death in epilepsy in the GATORopathies or favourable epilepsy surgery outcomes in focal cortical dysplasia type II due to somatic brain mutations. Lastly, we discuss the potential therapeutic application of mechanistic target of rapamycin inhibitors for drug-resistant seizures in GATOR1-related epilepsies and focal cortical dysplasia type II.
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Affiliation(s)
- Patrick B Moloney
- FutureNeuro, the Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, Dublin, D02 VN51, Ireland
| | - Gianpiero L Cavalleri
- FutureNeuro, the Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, Dublin, D02 VN51, Ireland
| | - Norman Delanty
- FutureNeuro, the Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, Royal College of Surgeons in Ireland, Dublin, D02 VN51, Ireland
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16
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Abstract
The presence of unprovoked, recurrent seizures, particularly when drug resistant and associated with cognitive and behavioral deficits, warrants investigation for an underlying genetic cause. This article provides an overview of the major classes of genes associated with epilepsy phenotypes divided into functional categories along with the recommended work-up and therapeutic considerations. Gene discovery in epilepsy supports counseling and anticipatory guidance but also opens the door for precision medicine guiding therapy with a focus on those with disease-modifying effects.
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Affiliation(s)
- Luis A Martinez
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Yi-Chen Lai
- Department of Pediatrics, Section of Pediatric Critical Care Medicine, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - J Lloyd Holder
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA
| | - Anne E Anderson
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Drive, Houston, TX 77030, USA.
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17
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Nguyen LH, Bordey A. Corrigendum: Convergent and Divergent Mechanisms of Epileptogenesis in mTORopathies. Front Neuroanat 2021; 15:715363. [PMID: 34295225 PMCID: PMC8290855 DOI: 10.3389/fnana.2021.715363] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 01/16/2023] Open
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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18
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Khoshkhoo S, Lal D, Walsh CA. Application of single cell genomics to focal epilepsies: A call to action. Brain Pathol 2021; 31:e12958. [PMID: 34196990 PMCID: PMC8412079 DOI: 10.1111/bpa.12958] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 03/17/2021] [Indexed: 12/24/2022] Open
Abstract
Focal epilepsies are the largest epilepsy subtype and associated with significant morbidity. Somatic variation is a newly recognized genetic mechanism underlying a subset of focal epilepsies, but little is known about the processes through which somatic mosaicism causes seizures, the cell types carrying the pathogenic variants, or their developmental origin. Meanwhile, the inception of single cell biology has completely revolutionized the study of neurological diseases and has the potential to answer some of these key questions. Focusing on single cell genomics, transcriptomics, and epigenomics in focal epilepsy research, circumvents the averaging artifact associated with studying bulk brain tissue and offers the kind of granularity that is needed for investigating the consequences of somatic mosaicism. Here we have provided a brief overview of some of the most developed single cell techniques and the major considerations around applying them to focal epilepsy research.
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Affiliation(s)
- Sattar Khoshkhoo
- Department of Neurology, Brigham and Women's Hospital, Boston, MA, USA.,Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.,Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Dennis Lal
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.,Cologne Center for Genomics, University of Cologne, Cologne, Germany.,Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.,Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
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19
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Yu L, Wei J, Liu P. Attacking the PI3K/Akt/mTOR signaling pathway for targeted therapeutic treatment in human cancer. Semin Cancer Biol 2021; 85:69-94. [PMID: 34175443 DOI: 10.1016/j.semcancer.2021.06.019] [Citation(s) in RCA: 152] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 06/10/2021] [Accepted: 06/22/2021] [Indexed: 02/08/2023]
Abstract
Cancer is the second leading cause of human death globally. PI3K/Akt/mTOR signaling is one of the most frequently dysregulated signaling pathways observed in cancer patients that plays crucial roles in promoting tumor initiation, progression and therapy responses. This is largely due to that PI3K/Akt/mTOR signaling is indispensable for many cellular biological processes, including cell growth, metastasis, survival, metabolism, and others. As such, small molecule inhibitors targeting major kinase components of the PI3K/Akt/mTOR signaling pathway have drawn extensive attention and been developed and evaluated in preclinical models and clinical trials. Targeting a single kinase component within this signaling usually causes growth arrest rather than apoptosis associated with toxicity-induced adverse effects in patients. Combination therapies including PI3K/Akt/mTOR inhibitors show improved patient response and clinical outcome, albeit developed resistance has been reported. In this review, we focus on revealing the mechanisms leading to the hyperactivation of PI3K/Akt/mTOR signaling in cancer and summarizing efforts for developing PI3K/Akt/mTOR inhibitors as either mono-therapy or combination therapy in different cancer settings. We hope that this review will facilitate further understanding of the regulatory mechanisms governing dysregulation of PI3K/Akt/mTOR oncogenic signaling in cancer and provide insights into possible future directions for targeted therapeutic regimen for cancer treatment, by developing new agents, drug delivery systems, or combination regimen to target the PI3K/Akt/mTOR signaling pathway. This information will also provide effective patient stratification strategy to improve the patient response and clinical outcome for cancer patients with deregulated PI3K/Akt/mTOR signaling.
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Affiliation(s)
- Le Yu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | | | - Pengda Liu
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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20
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Zhang L, Huang T, Teaw S, Nguyen LH, Hsieh LS, Gong X, Burns LH, Bordey A. Filamin A inhibition reduces seizure activity in a mouse model of focal cortical malformations. Sci Transl Med 2021; 12:12/531/eaay0289. [PMID: 32075941 DOI: 10.1126/scitranslmed.aay0289] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 10/28/2019] [Accepted: 12/28/2019] [Indexed: 12/17/2022]
Abstract
Epilepsy treatments for patients with mechanistic target of rapamycin (mTOR) disorders, such as tuberous sclerosis complex (TSC) or focal cortical dysplasia type II (FCDII), are urgently needed. In these patients, the presence of focal cortical malformations is associated with the occurrence of lifelong epilepsy, leading to severe neurological comorbidities. Here, we show that the expression of the actin cross-linking protein filamin A (FLNA) is increased in resected cortical tissue that is responsible for seizures in patients with FCDII and in mice modeling TSC and FCDII with mutations in phosphoinositide 3-kinase (PI3K)-ras homolog enriched in brain (Rheb) pathway genes. Normalizing FLNA expression in these mice through genetic knockdown limited cell misplacement and neuronal dysmorphogenesis, two hallmarks of focal cortical malformations. In addition, Flna knockdown reduced seizure frequency independently of mTOR signaling. Treating mice with a small molecule targeting FLNA, PTI-125, before the onset of seizures alleviated neuronal abnormalities and reduced seizure frequency compared to vehicle-treated mice. In addition, the treatment was also effective when injected after seizure onset in juvenile and adult mice. These data suggest that targeting FLNA with either short hairpin RNAs or the small molecule PTI-125 might be effective in reducing seizures in patients with TSC and FCDII bearing mutations in PI3K-Rheb pathway genes.
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Affiliation(s)
- Longbo Zhang
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA.,Department of Neurosurgery, Xiangya Hospital, Central South University, 87 Xiangya Street, Changsha, Hunan 410008, China
| | - Tianxiang Huang
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA.,Department of Neurosurgery, Xiangya Hospital, Central South University, 87 Xiangya Street, Changsha, Hunan 410008, China
| | - Shannon Teaw
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA
| | - Lena H Nguyen
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA
| | - Lawrence S Hsieh
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA
| | - Xuan Gong
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA.,Department of Neurosurgery, Xiangya Hospital, Central South University, 87 Xiangya Street, Changsha, Hunan 410008, China
| | | | - Angélique Bordey
- Departments of Neurosurgery and Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8082, USA.
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21
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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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22
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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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23
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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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24
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Lee WS, Baldassari S, Chipaux M, Adle-Biassette H, Stephenson SEM, Maixner W, Harvey AS, Lockhart PJ, Baulac S, Leventer RJ. Gradient of brain mosaic RHEB variants causes a continuum of cortical dysplasia. Ann Clin Transl Neurol 2021; 8:485-490. [PMID: 33434304 PMCID: PMC7886042 DOI: 10.1002/acn3.51286] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 01/03/2023] Open
Abstract
Focal cortical dysplasia (FCD) and hemimegalencephaly (HME) are related malformations with shared etiologies. We report three patients with a spectrum of cortical malformations associated with pathogenic brain-specific somatic Ras homolog enriched in brain (RHEB) variants. The somatic variant load directly correlated with the size of the malformation, with upregulated mTOR activity confirmed in dysplastic tissues. Laser capture microdissection showed enrichment of RHEB variants in dysmorphic neurons and balloon cells. Our findings support the role of RHEB in a spectrum of cortical malformations confirming that FCD and HME represent a disease continuum, with the extent of dysplastic brain directly correlated with the somatic variant load.
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Affiliation(s)
- Wei Shern Lee
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Parkville, 3052, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, 3052, Australia
| | - Sara Baldassari
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Paris, F-75013, France
| | - Mathilde Chipaux
- Department of Pediatric Neurosurgery, Rothschild Foundation Hospital, Paris, F-75019, France
| | - Homa Adle-Biassette
- INSERM, UMR 1141, Hôpital Robert-Debré, Paris, 75019, France.,Faculté de Médecine Denis Diderot, Université Paris 7, Paris, France.,Service d'Anatomie et de Cytologie Pathologiques, Hôpital Lariboisière, APHP, Paris, 75010, France
| | - Sarah E M Stephenson
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Parkville, 3052, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, 3052, Australia
| | - Wirginia Maixner
- Department of Paediatrics, The University of Melbourne, Parkville, 3052, Australia.,Murdoch Children's Research Institute, Parkville, 3052, Australia.,Department of Neurosurgery, The Royal Children's Hospital, Parkville, 3052, Australia
| | - A Simon Harvey
- Department of Paediatrics, The University of Melbourne, Parkville, 3052, Australia.,Murdoch Children's Research Institute, Parkville, 3052, Australia.,Department of Neurology, The Royal Children's Hospital, Parkville, 3052, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Parkville, 3052, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, 3052, Australia
| | - Stéphanie Baulac
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Paris, F-75013, France
| | - Richard J Leventer
- Department of Paediatrics, The University of Melbourne, Parkville, 3052, Australia.,Murdoch Children's Research Institute, Parkville, 3052, Australia.,Department of Neurology, The Royal Children's Hospital, Parkville, 3052, Australia
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25
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Niu M, Zheng N, Wang Z, Gao Y, Luo X, Chen Z, Fu X, Wang Y, Wang T, Liu M, Yao T, Yao P, Meng J, Zhou Y, Ge Y, Wang Z, Ma Q, Xu H, Zhang YW. RAB39B Deficiency Impairs Learning and Memory Partially Through Compromising Autophagy. Front Cell Dev Biol 2020; 8:598622. [PMID: 33364235 PMCID: PMC7753041 DOI: 10.3389/fcell.2020.598622] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 11/16/2020] [Indexed: 12/14/2022] Open
Abstract
RAB39B is located on the X chromosome and encodes the RAB39B protein that belongs to the RAB family. Mutations in RAB39B are known to be associated with X-linked intellectual disability (XLID), Parkinson’s disease, and autism. However, the patho/physiological functions of RAB39B remain largely unknown. In the present study, we established Rab39b knockout (KO) mice, which exhibited overall normal birth rate and morphologies as wild type mice. However, Rab39b deficiency led to reduced anxiety and impaired learning and memory in 2 months old mice. Deletion of Rab39b resulted in impairments of synaptic structures and functions, with reductions in NMDA receptors in the postsynaptic density (PSD). RAB39B deficiency also compromised autophagic flux at basal level, which could be overridden by rapamycin-induced autophagy activation. Further, treatment with rapamycin partially rescued impaired memory and synaptic plasticity in Rab39b KO mice, without affecting the PSD distribution of NMDA receptors. Together, these results suggest that RAB39B plays an important role in regulating both autophagy and synapse formation, and that targeting autophagy may have potential for treating XLID caused by RAB39B loss-of-function mutations.
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Affiliation(s)
- Mengxi Niu
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Naizhen Zheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Zijie Wang
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, Xiamen, China
| | - Yue Gao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Xianghua Luo
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Zhicai Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Xing Fu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Yanyan Wang
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Ting Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Manqing Liu
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Tingting Yao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Peijie Yao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Jian Meng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Yunqiang Zhou
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Yunlong Ge
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, Xiamen, China
| | - Zhanxiang Wang
- Department of Neurosurgery, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Qilin Ma
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Yun-Wu Zhang
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
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26
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Feliciano DM. The Neurodevelopmental Pathogenesis of Tuberous Sclerosis Complex (TSC). Front Neuroanat 2020; 14:39. [PMID: 32765227 PMCID: PMC7381175 DOI: 10.3389/fnana.2020.00039] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/10/2020] [Indexed: 12/22/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is a model disorder for understanding brain development because the genes that cause TSC are known, many downstream molecular pathways have been identified, and the resulting perturbations of cellular events are established. TSC, therefore, provides an intellectual framework to understand the molecular and biochemical pathways that orchestrate normal brain development. The TSC1 and TSC2 genes encode Hamartin and Tuberin which form a GTPase activating protein (GAP) complex. Inactivating mutations in TSC genes (TSC1/TSC2) cause sustained Ras homologue enriched in brain (RHEB) activation of the mammalian isoform of the target of rapamycin complex 1 (mTORC1). TOR is a protein kinase that regulates cell size in many organisms throughout nature. mTORC1 inhibits catabolic processes including autophagy and activates anabolic processes including mRNA translation. mTORC1 regulation is achieved through two main upstream mechanisms. The first mechanism is regulation by growth factor signaling. The second mechanism is regulation by amino acids. Gene mutations that cause too much or too little mTORC1 activity lead to a spectrum of neuroanatomical changes ranging from altered brain size (micro and macrocephaly) to cortical malformations to Type I neoplasias. Because somatic mutations often underlie these changes, the timing, and location of mutation results in focal brain malformations. These mutations, therefore, provide gain-of-function and loss-of-function changes that are a powerful tool to assess the events that have gone awry during development and to determine their functional physiological consequences. Knowledge about the TSC-mTORC1 pathway has allowed scientists to predict which upstream and downstream mutations should cause commensurate neuroanatomical changes. Indeed, many of these predictions have now been clinically validated. A description of clinical imaging and histochemical findings is provided in relation to laboratory models of TSC that will allow the reader to appreciate how human pathology can provide an understanding of the fundamental mechanisms of development.
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Affiliation(s)
- David M Feliciano
- Department of Biological Sciences, Clemson University, Clemson, SC, United States
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27
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Jourdon A, Fasching L, Scuderi S, Abyzov A, Vaccarino FM. The role of somatic mosaicism in brain disease. Curr Opin Genet Dev 2020; 65:84-90. [PMID: 32622340 DOI: 10.1016/j.gde.2020.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 04/26/2020] [Accepted: 05/03/2020] [Indexed: 12/25/2022]
Abstract
In this review we discuss the importance of genetic somatic mosaicism and its impact on brain diseases. We start from introducing the different types of somatic mutations, their frequencies and abundances across development and lifespan. We then describe how weakness in DNA repair mechanisms influences their prevalence. Finally, we address their functional consequences in the brain and review recent research showing their unsuspected importance in several neurodevelopmental, psychiatric, and neurodegenerative diseases.
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Affiliation(s)
| | - Liana Fasching
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Soraya Scuderi
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Alexej Abyzov
- Department of Health Sciences Research, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Flora M Vaccarino
- Child Study Center, Yale University, New Haven, CT 06520, USA; Department of Neuroscience, Yale University, New Haven, CT 06520, USA.
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