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Ferro A, Arshad A, Boyd L, Stanley T, Berisha A, Vrudhula U, Gomez AM, Borniger JC, Cheadle L. The cytokine receptor Fn14 is a molecular brake on neuronal activity that mediates circadian function in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.02.587786. [PMID: 38617238 PMCID: PMC11014623 DOI: 10.1101/2024.04.02.587786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
To survive, organisms must adapt to a staggering diversity of environmental signals, ranging from sensory information to pathogenic infection, across the lifespan. At the same time, organisms intrinsically generate biological oscillations, such as circadian rhythms, without input from the environment. While the nervous system is well-suited to integrate extrinsic and intrinsic cues, how the brain balances these influences to shape biological function system-wide is not well understood at the molecular level. Here, we demonstrate that the cytokine receptor Fn14, previously identified as a mediator of sensory experience-dependent synaptic refinement during brain development, regulates neuronal activity and function in adult mice in a time-of-day-dependent manner. We show that a subset of excitatory pyramidal (PYR) neurons in the CA1 subregion of the hippocampus increase Fn14 expression when neuronal activity is heightened. Once expressed, Fn14 constrains the activity of these same PYR neurons, suggesting that Fn14 operates as a molecular brake on neuronal activity. Strikingly, differences in PYR neuron activity between mice lacking or expressing Fn14 were most robust at daily transitions between light and dark, and genetic ablation of Fn14 caused aberrations in circadian rhythms, sleep-wake states, and sensory-cued and spatial memory. At the cellular level, microglia contacted fewer, but larger, excitatory synapses in CA1 in the absence of Fn14, suggesting that these brain-resident immune cells may dampen neuronal activity by modifying synaptic inputs onto PYR neurons. Finally, mice lacking Fn14 exhibited heightened susceptibility to chemically induced seizures, implicating Fn14 in disorders characterized by hyperexcitation, such as epilepsy. Altogether, these findings reveal that cytokine receptors that mediates inflammation in the periphery, such as Fn14, can also play major roles in healthy neurological function in the adult brain downstream of both extrinsic and intrinsic cues.
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Affiliation(s)
- Austin Ferro
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
| | - Anosha Arshad
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
- Department of Neurobiology and Behavior, Stony Brook University Renaissance School of Medicine, Stony Brook, NY 11794, USA
| | - Leah Boyd
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
| | - Tess Stanley
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
| | - Adrian Berisha
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
| | - Uma Vrudhula
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
| | - Adrian M. Gomez
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
| | | | - Lucas Cheadle
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11740, USA
- Howard Hughes Medical Institute, Cold Spring Harbor, NY 11740, USA
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2
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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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Goul C, Peruzzo R, Zoncu R. The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease. Nat Rev Mol Cell Biol 2023; 24:857-875. [PMID: 37612414 DOI: 10.1038/s41580-023-00641-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/25/2023]
Abstract
The Ser/Thr kinase mechanistic target of rapamycin (mTOR) is a central regulator of cellular metabolism. As part of mTOR complex 1 (mTORC1), mTOR integrates signals such as the levels of nutrients, growth factors, energy sources and oxygen, and triggers responses that either boost anabolism or suppress catabolism. mTORC1 signalling has wide-ranging consequences for the growth and homeostasis of key tissues and organs, and its dysregulated activity promotes cancer, type 2 diabetes, neurodegeneration and other age-related disorders. How mTORC1 integrates numerous upstream cues and translates them into specific downstream responses is an outstanding question with major implications for our understanding of physiology and disease mechanisms. In this Review, we discuss recent structural and functional insights into the molecular architecture of mTORC1 and its lysosomal partners, which have greatly increased our mechanistic understanding of nutrient-dependent mTORC1 regulation. We also discuss the emerging involvement of aberrant nutrient-mTORC1 signalling in multiple diseases.
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Affiliation(s)
- Claire Goul
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberta Peruzzo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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4
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Kao HY, Yao Y, Yang T, Ziobro J, Zylinski M, Mir MY, Hu S, Cao R, Borna NN, Banerjee R, Parent JM, Wang S, Leventhal DK, Li P, Wang Y. Sudden Unexpected Death in Epilepsy and Respiratory Defects in a Mouse Model of DEPDC5-Related Epilepsy. Ann Neurol 2023; 94:812-824. [PMID: 37606181 PMCID: PMC10592102 DOI: 10.1002/ana.26773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 08/23/2023]
Abstract
OBJECTIVES DEPDC5 is a common causative gene in familial focal epilepsy with or without malformations of cortical development. Its pathogenic variants also confer a significantly higher risk for sudden unexpected death in epilepsy (SUDEP), providing opportunities to investigate the pathophysiology intersecting neurodevelopment, epilepsy, and cardiorespiratory function. There is an urgent need to gain a mechanistic understanding of DEPDC5-related epilepsy and SUDEP, identify biomarkers for patients at high risk, and develop preventive interventions. METHODS Depdc5 was specifically deleted in excitatory or inhibitory neurons in the mouse brain to determine neuronal subtypes that drive epileptogenesis and SUDEP. Electroencephalogram (EEG), cardiac, and respiratory recordings were performed to determine cardiorespiratory phenotypes associated with SUDEP. Baseline respiratory function and the response to hypoxia challenge were also studied in these mice. RESULTS Depdc5 deletion in excitatory neurons in cortical layer 5 and dentate gyrus caused frequent generalized tonic-clonic seizures and SUDEP in young adult mice, but Depdc5 deletion in cortical interneurons did not. EEG suppression immediately following ictal offset was observed in fatal and non-fatal seizures, but low amplitude rhythmic theta frequency activity was lost only in fatal seizures. In addition, these mice developed baseline respiratory dysfunction prior to SUDEP, during which ictal apnea occurred long before terminal cardiac asystole. INTERPRETATION Depdc5 deletion in excitatory neurons is sufficient to cause DEPDC5-related epilepsy and SUDEP. Ictal apnea and respiratory dysregulation play critical roles in SUDEP. Our study also provides a novel mouse model to investigate the underlying mechanisms of DEPDC5-related epilepsy and SUDEP. ANN NEUROL 2023;94:812-824.
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Affiliation(s)
- Hsin-Yi Kao
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Yilong Yao
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Tao Yang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Julie Ziobro
- Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA
| | - Mary Zylinski
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Mohd Yaqub Mir
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Shuntong Hu
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Runnan Cao
- Department of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | | | - Rajat Banerjee
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Jack M. Parent
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
- Michgian Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Shuo Wang
- Department of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Daniel K. Leventhal
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
- Parkinson Disease Foundation Research Center of Excellence, University of Michigan, Ann Arbor, MI, USA
| | - Peng Li
- Michgian Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Biologic and Material Sciences, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Yu Wang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- VA Ann Arbor Healthcare System, Ann Arbor, MI 48105, USA
- Michgian Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
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Dhamne SC, Modi ME, Gray A, Bonazzi S, Craig L, Bainbridge E, Lalani L, Super CE, Schaeffer S, Capre K, Lubicka D, Liang G, Burdette D, McTighe SM, Gurnani S, Vermudez SAD, Curtis D, Wilson CJ, Hameed MQ, D'Amore A, Rotenberg A, Sahin M. Seizure reduction in TSC2-mutant mouse model by an mTOR catalytic inhibitor. Ann Clin Transl Neurol 2023; 10:1790-1801. [PMID: 37545094 PMCID: PMC10578885 DOI: 10.1002/acn3.51868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 07/14/2023] [Accepted: 07/23/2023] [Indexed: 08/08/2023] Open
Abstract
OBJECTIVE Tuberous sclerosis complex (TSC) is a neurodevelopmental disorder caused by autosomal-dominant pathogenic variants in either the TSC1 or TSC2 gene, and it is characterized by hamartomas in multiple organs, such as skin, kidney, lung, and brain. These changes can result in epilepsy, learning disabilities, and behavioral complications, among others. The mechanistic link between TSC and the mechanistic target of the rapamycin (mTOR) pathway is well established, thus mTOR inhibitors can potentially be used to treat the clinical manifestations of the disorder, including epilepsy. METHODS In this study, we tested the efficacy of a novel mTOR catalytic inhibitor (here named Tool Compound 1 or TC1) previously reported to be more brain-penetrant compared with other mTOR inhibitors. Using a well-characterized hypomorphic Tsc2 mouse model, which displays a translationally relevant seizure phenotype, we tested the efficacy of TC1. RESULTS Our results show that chronic treatment with this novel mTOR catalytic inhibitor (TC1), which affects both the mTORC1 and mTORC2 signaling complexes, reduces seizure burden, and extends the survival of Tsc2 hypomorphic mice, restoring species typical weight gain over development. INTERPRETATION Novel mTOR catalytic inhibitor TC1 exhibits a promising therapeutic option in the treatment of TSC.
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Affiliation(s)
- Sameer C. Dhamne
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Meera E. Modi
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Audrey Gray
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | - Simone Bonazzi
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | - Lucas Craig
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | - Elizabeth Bainbridge
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Lahin Lalani
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Chloe E. Super
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Samantha Schaeffer
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Ketthsy Capre
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | - Danuta Lubicka
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | - Guiqing Liang
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | - Doug Burdette
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | | | - Sarika Gurnani
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Sheryl Anne D. Vermudez
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Daniel Curtis
- Novartis Institutes for Biomedical ResearchCambridgeMassachusettsUSA
| | | | - Mustafa Q. Hameed
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Angelica D'Amore
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Alexander Rotenberg
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Mustafa Sahin
- F.M. Kirby Neurobiology Center, Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
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6
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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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7
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Auvin S, Baulac S. mTOR-therapy and targeted treatment opportunities in mTOR-related epilepsies associated with cortical malformations. Rev Neurol (Paris) 2023; 179:337-344. [PMID: 36906459 DOI: 10.1016/j.neurol.2022.12.007] [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: 10/27/2022] [Revised: 12/08/2022] [Accepted: 12/13/2022] [Indexed: 03/11/2023]
Abstract
Dysregulation of the mTOR pathway is now well documented in several neurodevelopmental disorders associated with epilepsy. Mutations of mTOR pathway genes are involved in tuberous sclerosis complex (TSC) as well as in a range of cortical malformations from hemimegalencephaly (HME) to type II focal cortical dysplasia (FCD II), leading to the concept of "mTORopathies" (mTOR pathway-related malformations). This suggests that mTOR inhibitors (notably rapamycin (sirolimus), and everolimus) could be used as antiseizure medication. In this review, we provide an overview of pharmacological treatments targeting the mTOR pathway for epilepsy based on lectures from the ILAE French Chapter meeting in October 2022 in Grenoble. There is strong preclinical evidence for the antiseizure effects of mTOR inhibitors in TSC and cortical malformation mouse models. There are also open studies on the antiseizure effects of mTOR inhibitors, as well as one phase III study showing the antiseizure effect of everolimus in TSC patients. Finally, we discuss to which extent mTOR inhibitors might have properties beyond the antiseizure effect on associated neuropsychiatric comorbidities. We also discuss a new way of treatment on the mTOR pathways.
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Affiliation(s)
- S Auvin
- Service de neurologie pédiatrique, EpiCARE ERN membre, Hôpital Robert Debré, AP-HP, Paris, France; Université Paris-Cité, Inserm NeuroDiderot, Paris, France; Institut Universitaire de France (IUF), Paris, France.
| | - S Baulac
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, 75013 Paris, France
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8
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Kong X, Shu X, Wang J, Liu D, Ni Y, Zhao W, Wang L, Gao Z, Chen J, Yang B, Guo X, Wang Z. Fine-tuning of mTOR signaling by the UBE4B-KLHL22 E3 ubiquitin ligase cascade in brain development. Development 2022; 149:286123. [PMID: 36440598 PMCID: PMC9845739 DOI: 10.1242/dev.201286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 11/15/2022] [Indexed: 11/29/2022]
Abstract
Spatiotemporal regulation of the mechanistic target of rapamycin (mTOR) pathway is pivotal for establishment of brain architecture. Dysregulation of mTOR signaling is associated with a variety of neurodevelopmental disorders. Here, we demonstrate that the UBE4B-KLHL22 E3 ubiquitin ligase cascade regulates mTOR activity in neurodevelopment. In a mouse model with UBE4B conditionally deleted in the nervous system, animals display severe growth defects, spontaneous seizures and premature death. Loss of UBE4B in the brains of mutant mice results in depletion of neural precursor cells and impairment of neurogenesis. Mechanistically, UBE4B polyubiquitylates and degrades KLHL22, an E3 ligase previously shown to degrade the GATOR1 component DEPDC5. Deletion of UBE4B causes upregulation of KLHL22 and hyperactivation of mTOR, leading to defective proliferation and differentiation of neural precursor cells. Suppression of KLHL22 expression reverses the elevated activity of mTOR caused by acute local deletion of UBE4B. Prenatal treatment with the mTOR inhibitor rapamycin rescues neurogenesis defects in Ube4b mutant mice. Taken together, these findings demonstrate that UBE4B and KLHL22 are essential for maintenance and differentiation of the precursor pool through fine-tuning of mTOR activity.
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Affiliation(s)
- Xiangxing Kong
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Xin Shu
- Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jiachuan Wang
- Zhejiang University-University of Edinburgh Institute, Zhejiang University, Haining 314400, China,Deanery of Biomedical Sciences, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, EH8 9YL, UK
| | - Dandan Liu
- Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yingchun Ni
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Weiqi Zhao
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Lebo Wang
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Zhihua Gao
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Jiadong Chen
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China
| | - Bing Yang
- Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China,Authors for correspondence (; ; )
| | - Xing Guo
- Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China,Authors for correspondence (; ; )
| | - Zhiping Wang
- Department of Neurobiology and Department of Neurology of Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou 310058, China,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou 310058, China,Authors for correspondence (; ; )
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9
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The Effects of Dietary Interventions on Brain Aging and Neurological Diseases. Nutrients 2022; 14:nu14235086. [PMID: 36501116 PMCID: PMC9740746 DOI: 10.3390/nu14235086] [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: 11/02/2022] [Revised: 11/17/2022] [Accepted: 11/23/2022] [Indexed: 12/02/2022] Open
Abstract
Dietary interventions can ameliorate age-related neurological decline. Decades of research of in vitro studies, animal models, and clinical trials support their ability and efficacy to improve behavioral outcomes by inducing biochemical and physiological changes that lead to a more resilient brain. Dietary interventions including calorie restriction, alternate day fasting, time restricted feeding, and fasting mimicking diets not only improve normal brain aging but also slow down, or even reverse, the progression of neurological diseases. In this review, we focus on the effects of intermittent and periodic fasting on improving phenotypic outcomes, such as cognitive and motor-coordination decline, in the normal aging brain through an increase in neurogenesis and synaptic plasticity, and decrease in neuroinflammation, mitochondrial dysfunction, and oxidative stress. We summarize the results of various dietary interventions in animal models of age-related neurological diseases such as Alzheimer's disease, Parkinson's disease, epilepsy, and Multiple Sclerosis and discuss the results of clinical trials that explore the feasibility of dietary interventions in the prevention and treatment of these diseases.
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10
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Iffland PH, Everett ME, Cobb-Pitstick KM, Bowser LE, Barnes AE, Babus JK, Romanowski AJ, Baybis M, Elziny S, Puffenberger EG, Gonzaga-Jauregui C, Poulopoulos A, Carson VJ, Crino PB. NPRL3 loss alters neuronal morphology, mTOR localization, cortical lamination and seizure threshold. Brain 2022; 145:3872-3885. [PMID: 35136953 PMCID: PMC10200289 DOI: 10.1093/brain/awac044] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/10/2021] [Accepted: 12/10/2021] [Indexed: 08/13/2023] Open
Abstract
Mutations in nitrogen permease regulator-like 3 (NPRL3), a component of the GATOR1 complex within the mTOR pathway, are associated with epilepsy and malformations of cortical development. Little is known about the effects of NPRL3 loss on neuronal mTOR signalling and morphology, or cerebral cortical development and seizure susceptibility. We report the clinical phenotypic spectrum of a founder NPRL3 pedigree (c.349delG, p.Glu117LysFS; n = 133) among Old Order Mennonites dating to 1727. Next, as a strategy to define the role of NPRL3 in cortical development, CRISPR/Cas9 Nprl3 knockout in Neuro2a cells in vitro and in foetal mouse brain in vivo was used to assess the effects of Nprl3 knockout on mTOR activation, subcellular mTOR localization, nutrient signalling, cell morphology and aggregation, cerebral cortical cytoarchitecture and network integrity. The NPRL3 pedigree exhibited an epilepsy penetrance of 28% and heterogeneous clinical phenotypes with a range of epilepsy semiologies, i.e. focal or generalized onset, brain imaging abnormalities, i.e. polymicrogyria, focal cortical dysplasia or normal imaging, and EEG findings, e.g. focal, multi-focal or generalized spikes, focal or generalized slowing. Whole exome analysis comparing a seizure-free group (n = 37) to those with epilepsy (n = 24) to search for gene modifiers for epilepsy did not identify a unique genetic modifier that explained the variability in seizure penetrance in this cohort. Nprl3 knockout in vitro caused mTOR pathway hyperactivation, cell soma enlargement and the formation of cellular aggregates seen in time-lapse videos that were prevented with the mTOR inhibitors rapamycin or torin1. In Nprl3 knockout cells, mTOR remained localized on the lysosome in a constitutively active conformation, as evidenced by phosphorylation of ribosomal S6 and 4E-BP1 proteins, even under nutrient starvation (amino acid-free) conditions, demonstrating that Nprl3 loss decouples mTOR activation from neuronal metabolic state. To model human malformations of cortical development associated with NPRL3 variants, we created a focal Nprl3 knockout in foetal mouse cortex by in utero electroporation and found altered cortical lamination and white matter heterotopic neurons, effects which were prevented with rapamycin treatment. EEG recordings showed network hyperexcitability and reduced seizure threshold to pentylenetetrazol treatment. NPRL3 variants are linked to a highly variable clinical phenotype which we propose results from mTOR-dependent effects on cell structure, cortical development and network organization.
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Affiliation(s)
- Philip H Iffland
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | | | | | | | - Allan E Barnes
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | - Janice K Babus
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | - Andrea J Romanowski
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | - Marianna Baybis
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | - Soad Elziny
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | | | | | - Alexandros Poulopoulos
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
| | | | - Peter B Crino
- University of Maryland School of Medicine Departments of Neurology and Pharmacology, Baltimore, MD 21201, USA
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11
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Ververi A, Zagaglia S, Menzies L, Baptista J, Caswell R, Baulac S, Ellard S, Lynch S, Jacques TS, Chawla MS, Heier M, Kulseth MA, Mero IL, Våtevik AK, Kraoua I, Ben Rhouma H, Ben Younes T, Miladi Z, Ben Youssef Turki I, Jones WD, Clement E, Eltze C, Mankad K, Merve A, Parker J, Hoskins B, Pressler R, Sudhakar S, DeVile C, Homfray T, Kaliakatsos M, Robinson R, Keim SMB, Habibi I, Reymond A, Sisodiya SM, Hurst JA. Germline homozygous missense DEPDC5 variants cause severe refractory early-onset epilepsy, macrocephaly and bilateral polymicrogyria. Hum Mol Genet 2022; 32:580-594. [PMID: 36067010 PMCID: PMC9896472 DOI: 10.1093/hmg/ddac225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 08/16/2022] [Accepted: 08/31/2022] [Indexed: 02/07/2023] Open
Abstract
DEPDC5 (DEP Domain-Containing Protein 5) encodes an inhibitory component of the mammalian target of rapamycin (mTOR) pathway and is commonly implicated in sporadic and familial focal epilepsies, both non-lesional and in association with focal cortical dysplasia. Germline pathogenic variants are typically heterozygous and inactivating. We describe a novel phenotype caused by germline biallelic missense variants in DEPDC5. Cases were identified clinically. Available records, including magnetic resonance imaging and electroencephalography, were reviewed. Genetic testing was performed by whole exome and whole-genome sequencing and cascade screening. In addition, immunohistochemistry was performed on skin biopsy. The phenotype was identified in nine children, eight of which are described in detail herein. Six of the children were of Irish Traveller, two of Tunisian and one of Lebanese origin. The Irish Traveller children shared the same DEPDC5 germline homozygous missense variant (p.Thr337Arg), whereas the Lebanese and Tunisian children shared a different germline homozygous variant (p.Arg806Cys). Consistent phenotypic features included extensive bilateral polymicrogyria, congenital macrocephaly and early-onset refractory epilepsy, in keeping with other mTOR-opathies. Eye and cardiac involvement and severe neutropenia were also observed in one or more patients. Five of the children died in infancy or childhood; the other four are currently aged between 5 months and 6 years. Skin biopsy immunohistochemistry was supportive of hyperactivation of the mTOR pathway. The clinical, histopathological and genetic evidence supports a causal role for the homozygous DEPDC5 variants, expanding our understanding of the biology of this gene.
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Affiliation(s)
| | | | | | | | - Richard Caswell
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | - Stephanie Baulac
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, F-75013 Paris, France
| | - Sian Ellard
- Exeter Genomics Laboratory, Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK
| | - Sally Lynch
- Academic Centre on Rare Diseases, University College Dublin School of Medicine and Medical Science, Dublin, Ireland,Department of Clinical Genetics, Children's Health Ireland (CHI) at Crumlin, Dublin, Ireland
| | | | - Thomas S Jacques
- Developmental Biology and Cancer Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK,Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | | | - Martin Heier
- Department of Clinical Neuroscience for Children, Oslo University Hospital, Oslo, Norway
| | - Mari Ann Kulseth
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Inger-Lise Mero
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | | | - Ichraf Kraoua
- Research Laboratory LR18SP04, Department of Child and Adolescent Neurology, National Institute Mongi Ben Hmida of Neurology, Tunis, Tunisia. Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Hanene Ben Rhouma
- Research Laboratory LR18SP04, Department of Child and Adolescent Neurology, National Institute Mongi Ben Hmida of Neurology, Tunis, Tunisia. Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Thouraya Ben Younes
- Research Laboratory LR18SP04, Department of Child and Adolescent Neurology, National Institute Mongi Ben Hmida of Neurology, Tunis, Tunisia. Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Zouhour Miladi
- Research Laboratory LR18SP04, Department of Child and Adolescent Neurology, National Institute Mongi Ben Hmida of Neurology, Tunis, Tunisia. Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Ilhem Ben Youssef Turki
- Research Laboratory LR18SP04, Department of Child and Adolescent Neurology, National Institute Mongi Ben Hmida of Neurology, Tunis, Tunisia. Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Wendy D Jones
- Department of Clinical Genetics & Genomic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Emma Clement
- Department of Clinical Genetics & Genomic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Christin Eltze
- Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Kshitij Mankad
- Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Ashirwad Merve
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Jennifer Parker
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Bethan Hoskins
- North Thames Genomic Laboratory Hub, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Ronit Pressler
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Sniya Sudhakar
- Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Catherine DeVile
- Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Tessa Homfray
- SW Thames Regional Genetics Service, St George's Hospital, St George's University of London, London, UK
| | - Marios Kaliakatsos
- Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Ponnudas (Prab) Prabhakar
- Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Robert Robinson
- Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | | | - Imen Habibi
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Alexandre Reymond
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Sanjay M Sisodiya
- To whom correspondence should be addressed at: Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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12
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Yuskaitis CJ, Modasia JB, Schrötter S, Rossitto LA, Groff KJ, Morici C, Mithal DS, Chakrabarty RP, Chandel NS, Manning BD, Sahin M. DEPDC5-dependent mTORC1 signaling mechanisms are critical for the anti-seizure effects of acute fasting. Cell Rep 2022; 40:111278. [PMID: 36044864 PMCID: PMC9508617 DOI: 10.1016/j.celrep.2022.111278] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/11/2022] [Accepted: 08/05/2022] [Indexed: 11/30/2022] Open
Abstract
Caloric restriction and acute fasting are known to reduce seizures but through unclear mechanisms. mTOR signaling has been suggested as a potential mechanism for seizure protection from fasting. We demonstrate that brain mTORC1 signaling is reduced after acute fasting of mice and that neuronal mTORC1 integrates GATOR1 complex-mediated amino acid and tuberous sclerosis complex (TSC)-mediated growth factor signaling. Neuronal mTORC1 is most sensitive to withdrawal of leucine, arginine, and glutamine, which are dependent on DEPDC5, a component of the GATOR1 complex. Metabolomic analysis reveals that Depdc5 neuronal-specific knockout mice are resistant to sensing significant fluctuations in brain amino acid levels after fasting. Depdc5 neuronal-specific knockout mice are resistant to the protective effects of fasting on seizures or seizure-induced death. These results establish that acute fasting reduces seizure susceptibility in a DEPDC5-dependent manner. Modulation of nutrients upstream of GATOR1 and mTORC1 could offer a rational therapeutic strategy for epilepsy treatment.
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Affiliation(s)
- Christopher J Yuskaitis
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jinita B Modasia
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Sandra Schrötter
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Leigh-Ana Rossitto
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Karenna J Groff
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Christopher Morici
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Divakar S Mithal
- Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; Section of Neurology, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Ram P Chakrabarty
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Navdeep S Chandel
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Brendan D Manning
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Mustafa Sahin
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Boston, MA, USA.
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13
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Molecular Mechanism and Regulation of Autophagy and Its Potential Role in Epilepsy. Cells 2022; 11:cells11172621. [PMID: 36078029 PMCID: PMC9455075 DOI: 10.3390/cells11172621] [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: 07/20/2022] [Revised: 08/14/2022] [Accepted: 08/22/2022] [Indexed: 01/18/2023] Open
Abstract
Autophagy is an evolutionally conserved degradation mechanism for maintaining cell homeostasis whereby cytoplasmic components are wrapped in autophagosomes and subsequently delivered to lysosomes for degradation. This process requires the concerted actions of multiple autophagy-related proteins and accessory regulators. In neurons, autophagy is dynamically regulated in different compartments including soma, axons, and dendrites. It determines the turnover of selected materials in a spatiotemporal control manner, which facilitates the formation of specialized neuronal functions. It is not surprising, therefore, that dysfunctional autophagy occurs in epilepsy, mainly caused by an imbalance between excitation and inhibition in the brain. In recent years, much attention has been focused on how autophagy may cause the development of epilepsy. In this article, we overview the historical landmarks and distinct types of autophagy, recent progress in the core machinery and regulation of autophagy, and biological roles of autophagy in homeostatic maintenance of neuronal structures and functions, with a particular focus on synaptic plasticity. We also discuss the relevance of autophagy mechanisms to the pathophysiology of epileptogenesis.
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14
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Park SM, Roache CE, Iffland PH, Moldenhauer HJ, Matychak KK, Plante AE, Lieberman AG, Crino PB, Meredith A. BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models. eLife 2022; 11:e77953. [PMID: 35819138 PMCID: PMC9275823 DOI: 10.7554/elife.77953] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 06/01/2022] [Indexed: 12/14/2022] Open
Abstract
KCNMA1 forms the pore of BK K+ channels, which regulate neuronal and muscle excitability. Recently, genetic screening identified heterozygous KCNMA1 variants in a subset of patients with debilitating paroxysmal non-kinesigenic dyskinesia, presenting with or without epilepsy (PNKD3). However, the relevance of KCNMA1 mutations and the basis for clinical heterogeneity in PNKD3 has not been established. Here, we evaluate the relative severity of three KCNMA1 patient variants in BK channels, neurons, and mice. In heterologous cells, BKN999S and BKD434G channels displayed gain-of-function (GOF) properties, whereas BKH444Q channels showed loss-of-function (LOF) properties. The relative degree of channel activity was BKN999S > BKD434G>WT > BKH444Q. BK currents and action potential firing were increased, and seizure thresholds decreased, in Kcnma1N999S/WT and Kcnma1D434G/WT transgenic mice but not Kcnma1H444Q/WT mice. In a novel behavioral test for paroxysmal dyskinesia, the more severely affected Kcnma1N999S/WT mice became immobile after stress. This was abrogated by acute dextroamphetamine treatment, consistent with PNKD3-affected individuals. Homozygous Kcnma1D434G/D434G mice showed similar immobility, but in contrast, homozygous Kcnma1H444Q/H444Q mice displayed hyperkinetic behavior. These data establish the relative pathogenic potential of patient alleles as N999S>D434G>H444Q and validate Kcnma1N999S/WT mice as a model for PNKD3 with increased seizure propensity.
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Affiliation(s)
- Su Mi Park
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Cooper E Roache
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Philip H Iffland
- Department of Neurology, University of Maryland School of MedicineBaltimoreUnited States
| | - Hans J Moldenhauer
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Katia K Matychak
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Amber E Plante
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Abby G Lieberman
- Department of Pharmacology, University of Maryland School of MedicineBaltimoreUnited States
| | - Peter B Crino
- Department of Neurology, University of Maryland School of MedicineBaltimoreUnited States
| | - Andrea Meredith
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
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15
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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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16
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Dentel B, Angeles-Perez L, Ren C, Jakkamsetti V, Holley AJ, Caballero D, Oh E, Gibson J, Pascual JM, Huber KM, Tu BP, Tsai PT. Increased glycine contributes to synaptic dysfunction and early mortality in Nprl2 seizure model. iScience 2022; 25:104334. [PMID: 35602938 PMCID: PMC9118754 DOI: 10.1016/j.isci.2022.104334] [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] [Received: 12/22/2020] [Revised: 09/16/2021] [Accepted: 04/26/2022] [Indexed: 10/25/2022] Open
Abstract
Targeted therapies for epilepsies associated with the mTORC1 signaling negative regulator GATOR1 are lacking. NPRL2 is a subunit of the GATOR1 complex and mutations in GATOR1 subunits, including NPRL2, are associated with epilepsy. To delineate the mechanisms underlying NPRL2-related epilepsies, we created a mouse (Mus musculus) model with neocortical loss of Nprl2. Mutant mice have increased mTORC1 signaling and exhibit spontaneous seizures. They also display abnormal synaptic function characterized by increased evoked and spontaneous EPSC and decreased evoked and spontaneous IPSC frequencies, respectively. Proteomic and metabolomics studies of Nprl2 mutants revealed alterations in known epilepsy-implicated proteins and metabolic pathways, including increases in the neurotransmitter, glycine. Furthermore, glycine actions on the NMDA receptor contribute to the electrophysiological and survival phenotypes of these mice. Taken together, in this neuronal Nprl2 model, we delineate underlying molecular, metabolic, and electrophysiological mechanisms contributing to mTORC1-related epilepsy, providing potential therapeutic targets for epilepsy.
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Affiliation(s)
- Brianne Dentel
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | | | - Chongyu Ren
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Vikram Jakkamsetti
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Andrew J. Holley
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Daniel Caballero
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Emily Oh
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Jay Gibson
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Juan M. Pascual
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Kimberly M. Huber
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Benjamin P. Tu
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Peter T. Tsai
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
- Departments of Pediatrics and Psychiatry, UT Southwestern Medical Center, Dallas, TX 75235, USA
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17
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Schrötter S, Yuskaitis CJ, MacArthur MR, Mitchell SJ, Hosios AM, Osipovich M, Torrence ME, Mitchell JR, Hoxhaj G, Sahin M, Manning BD. The non-essential TSC complex component TBC1D7 restricts tissue mTORC1 signaling and brain and neuron growth. Cell Rep 2022; 39:110824. [PMID: 35584673 PMCID: PMC9175135 DOI: 10.1016/j.celrep.2022.110824] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/21/2022] [Accepted: 04/23/2022] [Indexed: 11/16/2022] Open
Abstract
The tuberous sclerosis complex (TSC) 1 and 2 proteins associate with TBC1D7 to form the TSC complex, which is an essential suppressor of mTOR complex 1 (mTORC1), a ubiquitous driver of cell and tissue growth. Loss-of-function mutations in TSC1 or TSC2, but not TBC1D7, give rise to TSC, a pleiotropic disorder with aberrant activation of mTORC1 in various tissues. Here, we characterize mice with genetic deletion of Tbc1d7, which are viable with normal growth and development. Consistent with partial loss of function of the TSC complex, Tbc1d7 knockout (KO) mice display variable increases in tissue mTORC1 signaling with increased muscle fiber size but with strength and motor defects. Their most pronounced phenotype is brain overgrowth due to thickening of the cerebral cortex, with enhanced neuron-intrinsic mTORC1 signaling and growth. Thus, TBC1D7 is required for full TSC complex function in tissues, and the brain is particularly sensitive to its growth-suppressing activities.
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Affiliation(s)
- Sandra Schrötter
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Christopher J Yuskaitis
- Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Michael R MacArthur
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Sarah J Mitchell
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Aaron M Hosios
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Maria Osipovich
- Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Margaret E Torrence
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - James R Mitchell
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Gerta Hoxhaj
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Mustafa Sahin
- Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Brendan D Manning
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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18
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Samanta D. DEPDC5-related epilepsy: A comprehensive review. Epilepsy Behav 2022; 130:108678. [PMID: 35429726 DOI: 10.1016/j.yebeh.2022.108678] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/07/2022] [Accepted: 03/21/2022] [Indexed: 11/03/2022]
Abstract
DEPDC5-related epilepsy, caused by pathogenic germline variants(with or without additional somatic variants in the brain) of DEPDC5 (Dishevelled, Egl-10 and Pleckstrin domain-containing protein 5) gene, is a newly discovered predominantly focal epilepsy linked to enhanced mTORC1 pathway. DEPDC5-related epilepsy includes several familial epilepsy syndromes, including familial focal epilepsy with variable foci (FFEVF) and rare sporadic nonlesional focal epilepsy. DEPDC5 has been identified as one of the more common epilepsy genes linked to infantile spasms and sudden unexpected death (SUDEP). Although intelligence usually is unaffected in DEPDC5-related epilepsy, some people have been diagnosed with intellectual disabilities, autism spectrum disorder, and other psychiatric problems. DEPDC5 variants have also been found in 20% of individuals with various brain abnormalities, challenging the traditional distinction between lesional and nonlesional epilepsies. The most exciting development of DEPDC5 variants is the possibility of precision therapeutics using mTOR inhibitors, as evidenced with phenotypic rescue in many animal models. However, more research is needed to better understand the functional impact of diverse (particularly missense or splice-region) variants, the specific involvement of DEPDC5 in epileptogenesis, and the creation and utilization of precision therapies in humans. Precision treatments for DEPDC5-related epilepsy will benefit not only a small number of people with the condition, but they will also pave the way for new therapeutic approaches in epilepsy (including acquired epilepsies in which mTORC1 activation occurs, for example, post-traumatic epilepsy) and other neurological disorders involving a dysfunctional mTOR pathway.
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Affiliation(s)
- Debopam Samanta
- Child Neurology Section, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
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19
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Weng OY, Li Y, Wang LY. Modeling Epilepsy Using Human Induced Pluripotent Stem Cells-Derived Neuronal Cultures Carrying Mutations in Ion Channels and the Mechanistic Target of Rapamycin Pathway. Front Mol Neurosci 2022; 15:810081. [PMID: 35359577 PMCID: PMC8960276 DOI: 10.3389/fnmol.2022.810081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 02/02/2022] [Indexed: 11/17/2022] Open
Abstract
Epilepsy is a neurological disorder that affects over 65 million people globally. It is characterized by periods of seizure activity of the brain as a result of excitation and inhibition (E/I) imbalance, which is regarded as the core underpinning of epileptic activity. Both gain- and loss-of-function (GOF and LOF) mutations of ion channels, synaptic proteins and signaling molecules along the mechanistic target of rapamycin (mTOR) pathway have been linked to this imbalance. The pathogenesis of epilepsy often has its roots in the early stage of brain development. It remains a major challenge to extrapolate the findings from many animal models carrying these GOF or LOF mutations to the understanding of disease mechanisms in the developing human brain. Recent advent of the human pluripotent stem cells (hPSCs) technology opens up a new avenue to recapitulate patient conditions and to identify druggable molecular targets. In the following review, we discuss the progress, challenges and prospects of employing hPSCs-derived neural cultures to study epilepsy. We propose a tentative working model to conceptualize the possible impact of these GOF and LOF mutations in ion channels and mTOR signaling molecules on the morphological and functional remodeling of intrinsic excitability, synaptic transmission and circuits, ultimately E/I imbalance and behavioral phenotypes in epilepsy.
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Affiliation(s)
- Octavia Yifang Weng
- Program in Developmental and Stem Cell Biology, Sick Kids Research Institutes, Toronto, ON, Canada
- Program in Neuroscience and Mental Health, Sick Kids Research Institutes, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Yun Li
- Program in Developmental and Stem Cell Biology, Sick Kids Research Institutes, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- *Correspondence: Yun Li,
| | - Lu-Yang Wang
- Program in Neuroscience and Mental Health, Sick Kids Research Institutes, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Lu-Yang Wang,
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NPRL2 Inhibition of mTORC1 Controls Sodium Channel Expression and Brain Amino Acid Homeostasis. eNeuro 2022; 9:ENEURO.0317-21.2022. [PMID: 35165201 PMCID: PMC8896560 DOI: 10.1523/eneuro.0317-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/19/2022] Open
Abstract
Genetic mutations in nitrogen permease regulator-like 2 (NPRL2) are associated with a wide spectrum of familial focal epilepsies, autism, and sudden unexpected death of epileptics (SUDEP), but the mechanisms by which NPRL2 contributes to these effects are not well known. NPRL2 is a requisite subunit of the GAP activity toward Rags 1 (GATOR1) complex, which functions as a negative regulator of mammalian target of rapamycin complex 1 (mTORC1) kinase when intracellular amino acids are low. Here, we show that loss of NPRL2 expression in mouse excitatory glutamatergic neurons causes seizures before death, consistent with SUDEP in humans with epilepsy. Additionally, the absence of NPRL2 expression increases mTORC1-dependent signal transduction and significantly alters amino acid homeostasis in the brain. Loss of NPRL2 reduces dendritic branching and increases the strength of electrically stimulated action potentials (APs) in neurons. The increased AP strength is consistent with elevated expression of epilepsy-linked, voltage-gated sodium channels in the NPRL2-deficient brain. Targeted deletion of NPRL2 in primary neurons increases the expression of sodium channel Scn1A, whereas treatment with the pharmacological mTORC1 inhibitor called rapamycin prevents Scn1A upregulation. These studies demonstrate a novel role of NPRL2 and mTORC1 signaling in the regulation of sodium channels, which can contribute to seizures and early lethality.
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21
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Teran FA, Bravo E, Richerson GB. Sudden unexpected death in epilepsy: Respiratory mechanisms. HANDBOOK OF CLINICAL NEUROLOGY 2022; 189:153-176. [PMID: 36031303 PMCID: PMC10191258 DOI: 10.1016/b978-0-323-91532-8.00012-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Epilepsy is one of the most common chronic neurologic diseases, with a prevalence of 1% in the US population. Many people with epilepsy live normal lives, but are at risk of sudden unexpected death in epilepsy (SUDEP). This mysterious comorbidity of epilepsy causes premature death in 17%-50% of those with epilepsy. Most SUDEP occurs after a generalized seizure, and patients are typically found in bed in the prone position. Until recently, it was thought that SUDEP was due to cardiovascular failure, but patients who died while being monitored in hospital epilepsy units revealed that most SUDEP is due to postictal central apnea. Some cases may occur when seizures invade the amygdala and activate projections to the brainstem. Evidence suggests that the pathophysiology is linked to defects in the serotonin system and central CO2 chemoreception, and that there is considerable overlap with mechanisms thought to be involved in sudden infant death syndrome (SIDS). Future work is needed to identify biomarkers for patients at highest risk, improve ascertainment, develop methods to alert caregivers when SUDEP is imminent, and find effective approaches to prevent these fatal events.
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Affiliation(s)
- Frida A Teran
- Department of Neurology, University of Iowa, Iowa City, IA, United States; Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States.
| | - Eduardo Bravo
- Department of Neurology, University of Iowa, Iowa City, IA, United States
| | - George B Richerson
- Department of Neurology, University of Iowa, Iowa City, IA, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA, United States
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22
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Gozzelino L, Kochlamazashvili G, Baldassari S, Mackintosh AI, Licchetta L, Iovino E, Liu YC, Bennett CA, Bennett MF, Damiano JA, Zsurka G, Marconi C, Giangregorio T, Magini P, Kuijpers M, Maritzen T, Norata GD, Baulac S, Canafoglia L, Seri M, Tinuper P, Scheffer IE, Bahlo M, Berkovic SF, Hildebrand MS, Kunz WS, Giordano L, Bisulli F, Martini M, Haucke V, Hirsch E, Pippucci T. OUP accepted manuscript. Brain 2022; 145:2313-2331. [PMID: 35786744 PMCID: PMC9337808 DOI: 10.1093/brain/awac082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 01/13/2022] [Accepted: 02/12/2022] [Indexed: 11/20/2022] Open
Abstract
Epilepsy is one of the most frequent neurological diseases, with focal epilepsy accounting for the largest number of cases. The genetic alterations involved in focal epilepsy are far from being fully elucidated. Here, we show that defective lipid signalling caused by heterozygous ultra-rare variants in PIK3C2B, encoding for the class II phosphatidylinositol 3-kinase PI3K-C2β, underlie focal epilepsy in humans. We demonstrate that patients’ variants act as loss-of-function alleles, leading to impaired synthesis of the rare signalling lipid phosphatidylinositol 3,4-bisphosphate, resulting in mTORC1 hyperactivation. In vivo, mutant Pik3c2b alleles caused dose-dependent neuronal hyperexcitability and increased seizure susceptibility, indicating haploinsufficiency as a key driver of disease. Moreover, acute mTORC1 inhibition in mutant mice prevented experimentally induced seizures, providing a potential therapeutic option for a selective group of patients with focal epilepsy. Our findings reveal an unexpected role for class II PI3K-mediated lipid signalling in regulating mTORC1-dependent neuronal excitability in mice and humans.
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Affiliation(s)
| | | | | | - Albert Ian Mackintosh
- Department of Molecular Pharmacology and Cell Biology, Leibniz Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Strasse 10, 13125 Berlin, Germany
| | - Laura Licchetta
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Epilepsy Center (Reference Center for Rare and Complex Epilepsies—EpiCARE), Bologna, Italy
| | - Emanuela Iovino
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
| | - Yu Chi Liu
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, VictoriaAustralia
| | - Caitlin A Bennett
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Mark F Bennett
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, VictoriaAustralia
| | - John A Damiano
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Gábor Zsurka
- Department of Experimental Epileptology and Cognition Research and Department of Epileptology, University Bonn Medical Center, Venusberg Campus 1, D-53105 Bonn, Germany
| | - Caterina Marconi
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
| | - Tania Giangregorio
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
| | - Pamela Magini
- U.O. Genetica Medica, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Marijn Kuijpers
- Department of Molecular Pharmacology and Cell Biology, Leibniz Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Strasse 10, 13125 Berlin, Germany
| | - Tanja Maritzen
- Department of Molecular Pharmacology and Cell Biology, Leibniz Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Strasse 10, 13125 Berlin, Germany
- Department of Nanophysiology, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Giuseppe Danilo Norata
- Department of Excellence in Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan and Center for the Study of Atherosclerosis, SISA Bassini Hospital Cinisello B, Italy
| | - Stéphanie Baulac
- Sorbonne Université, Institut du Cerveau—Paris Brain Institute—ICM, Inserm, CNRS, F-75013 Paris, France
| | - Laura Canafoglia
- Unit of Integrated Diagnostics for Epilepsy, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Marco Seri
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy
- U.O. Genetica Medica, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Paolo Tinuper
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Epilepsy Center (Reference Center for Rare and Complex Epilepsies—EpiCARE), Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, Melbourne, Victoria, Australia
- Florey Institute for Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Melanie Bahlo
- Spedali Civili, Neuropsychiatric Department, Brescia, Italy
- Faculty of Biology, Chemistry, Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Michael S Hildebrand
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, Melbourne, Victoria, Australia
| | - Wolfram S Kunz
- Department of Experimental Epileptology and Cognition Research and Department of Epileptology, University Bonn Medical Center, Venusberg Campus 1, D-53105 Bonn, Germany
| | - Lucio Giordano
- Spedali Civili, Neuropsychiatric Department, Brescia, Italy
| | - Francesca Bisulli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Epilepsy Center (Reference Center for Rare and Complex Epilepsies—EpiCARE), Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | | | - Volker Haucke
- Volker Haucke Robert-Roessle-Strasse 10, 13125 Berlin, Germany E-mail:
| | - Emilio Hirsch
- Correspondence may also be addressed to: Emilio Hirsch via Nizza 52, 10126 Torino (TO), Italy E-mail:
| | - Tommaso Pippucci
- Correspondence to: Tommaso Pippucci Via Giuseppe Massarenti 9, 40138 Bologna (BO), Italy E-mail:
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23
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Bacq A, Roussel D, Bonduelle T, Zagaglia S, Maletic M, Ribierre T, Adle‐Biassette H, Marchal C, Jennesson M, An I, Picard F, Navarro V, Sisodiya SM, Baulac S. Cardiac Investigations in Sudden Unexpected Death in DEPDC5-Related Epilepsy. Ann Neurol 2022; 91:101-116. [PMID: 34693554 PMCID: PMC9299146 DOI: 10.1002/ana.26256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Germline loss-of-function mutations in DEPDC5, and in its binding partners (NPRL2/3) of the mammalian target of rapamycin (mTOR) repressor GATOR1 complex, cause focal epilepsies and increase the risk of sudden unexpected death in epilepsy (SUDEP). Here, we asked whether DEPDC5 haploinsufficiency predisposes to primary cardiac defects that could contribute to SUDEP and therefore impact the clinical management of patients at high risk of SUDEP. METHODS Clinical cardiac investigations were performed in 16 patients with pathogenic variants in DEPDC5, NPRL2, or NPRL3. Two novel Depdc5 mouse strains, a human HA-tagged Depdc5 strain and a Depdc5 heterozygous knockout with a neuron-specific deletion of the second allele (Depdc5c/- ), were generated to investigate the role of Depdc5 in SUDEP and cardiac activity during seizures. RESULTS Holter, echocardiographic, and electrocardiographic (ECG) examinations provided no evidence for altered clinical cardiac function in the patient cohort, of whom 3 DEPDC5 patients succumbed to SUDEP and 6 had a family history of SUDEP. There was no cardiac injury at autopsy in a postmortem DEPDC5 SUDEP case. The HA-tagged Depdc5 mouse revealed expression of Depdc5 in the brain, heart, and lungs. Simultaneous electroencephalographic-ECG records on Depdc5c/- mice showed that spontaneous epileptic seizures resulting in a SUDEP-like event are not preceded by cardiac arrhythmia. INTERPRETATION Mouse and human data show neither structural nor functional cardiac damage that might underlie a primary contribution to SUDEP in the spectrum of DEPDC5-related epilepsies. ANN NEUROL 2022;91:101-116.
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Affiliation(s)
- Alexandre Bacq
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
| | - Delphine Roussel
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
| | - Thomas Bonduelle
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
- Epilepsy and Neurology Department, Bordeaux University Hospital CenterBordeauxFrance
| | - Sara Zagaglia
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUK
- Chalfont Centre for EpilepsyBucksUK
| | - Marina Maletic
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
| | - Théo Ribierre
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
| | - Homa Adle‐Biassette
- Pathological Anatomy Department, University of Paris, AP‐HP, Lariboisière Hospital, DMU, DREAM, UMR 1141, INSERMParisFrance
| | - Cécile Marchal
- Epilepsy and Neurology Department, Bordeaux University Hospital CenterBordeauxFrance
| | - Mélanie Jennesson
- Department of PediatricsAmerican Memorial Hospital, Reims University Hospital CenterReimsFrance
| | - Isabelle An
- Epileptology Unit and Reference Center of Rare Epilepsies, Pitié‐Salpêtrière Hospital, AP‐HPParisFrance
| | - Fabienne Picard
- EEG and Epilepsy Unit, Department of Clinical NeurosciencesUniversity Hospitals and Faculty of Medicine of GenevaGenevaSwitzerland
| | - Vincent Navarro
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
- Epileptology Unit and Reference Center of Rare Epilepsies, Pitié‐Salpêtrière Hospital, AP‐HPParisFrance
| | - Sanjay M. Sisodiya
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUK
- Chalfont Centre for EpilepsyBucksUK
| | - Stéphanie Baulac
- Sorbonne University, Paris Brain Institute (ICM), Inserm, CNRS, AP‐HP, Pitié‐Salpêtrière HospitalParisFrance
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24
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Ishida S, Zhao D, Sawada Y, Hiraoka Y, Mashimo T, Tanaka K. Dorsal telencephalon-specific Nprl2- and Nprl3-knockout mice: novel mouse models for GATORopathy. Hum Mol Genet 2021; 31:1519-1530. [PMID: 34965576 PMCID: PMC9071434 DOI: 10.1093/hmg/ddab337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 09/28/2021] [Accepted: 11/12/2021] [Indexed: 11/30/2022] Open
Abstract
The most frequent genetic cause of focal epilepsies is variations in the GAP activity toward RAGs 1 complex genes DEP domain containing 5 (DEPDC5), nitrogen permease regulator 2-like protein (NPRL2) and nitrogen permease regulator 3-like protein (NPRL3). Because these variations are frequent and associated with a broad spectrum of focal epilepsies, a unique pathology categorized as GATORopathy can be conceptualized. Animal models recapitulating the clinical features of patients are essential to decipher GATORopathy. Although several genetically modified animal models recapitulate DEPDC5-related epilepsy, no models have been reported for NPRL2- or NPRL3-related epilepsies. Here, we conditionally deleted Nprl2 and Nprl3 from the dorsal telencephalon in mice [Emx1cre/+; Nprl2f/f (Nprl2-cKO) and Emx1cre/+; Nprl3f/f (Nprl3-cKO)] and compared their phenotypes with Nprl2+/−, Nprl3+/− and Emx1cre/+; Depdc5f/f (Depdc5-cKO) mice. Nprl2-cKO and Nprl3-cKO mice recapitulated the major abnormal features of patients—spontaneous seizures, and dysmorphic enlarged neuronal cells with increased mechanistic target of rapamycin complex 1 signaling—similar to Depdc5-cKO mice. Chronic postnatal rapamycin administration dramatically prolonged the survival period and inhibited seizure occurrence but not enlarged neuronal cells in Nprl2-cKO and Nprl3-cKO mice. However, the benefit of rapamycin after withdrawal was less durable in Nprl2- and Nprl3-cKO mice compared with Depdc5-cKO mice. Further studies using these conditional knockout mice will be useful for understanding GATORopathy and for the identification of novel therapeutic targets.
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Affiliation(s)
- Saeko Ishida
- Laboratory of Molecular Neuroscience, Medical Research Institute (MRI), Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
- Division of Animal Genetics, Laboratory Animal Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
| | - Di Zhao
- Laboratory of Molecular Neuroscience, Medical Research Institute (MRI), Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
- Division of Animal Genetics, Laboratory Animal Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
| | - Yuta Sawada
- Laboratory of Molecular Neuroscience, Medical Research Institute (MRI), Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Yuichi Hiraoka
- Laboratory of Molecular Neuroscience, Medical Research Institute (MRI), Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
- Laboratory of Genome Editing for Biomedical Research, MRI, TMDU, Tokyo, 101-0062, Japan
| | - Tomoji Mashimo
- Division of Animal Genetics, Laboratory Animal Research Center, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan
| | - Kohichi Tanaka
- Laboratory of Molecular Neuroscience, Medical Research Institute (MRI), Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
- Center for Brain Integration Research (CBIR), TMDU, Tokyo, 113-8510, Japan
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25
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Vasic V, Jones MSO, Haslinger D, Knaus LS, Schmeisser MJ, Novarino G, Chiocchetti AG. Translating the Role of mTOR- and RAS-Associated Signalopathies in Autism Spectrum Disorder: Models, Mechanisms and Treatment. Genes (Basel) 2021; 12:genes12111746. [PMID: 34828352 PMCID: PMC8624393 DOI: 10.3390/genes12111746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/25/2021] [Accepted: 10/28/2021] [Indexed: 12/23/2022] Open
Abstract
Mutations affecting mTOR or RAS signaling underlie defined syndromes (the so-called mTORopathies and RASopathies) with high risk for Autism Spectrum Disorder (ASD). These syndromes show a broad variety of somatic phenotypes including cancers, skin abnormalities, heart disease and facial dysmorphisms. Less well studied are the neuropsychiatric symptoms such as ASD. Here, we assess the relevance of these signalopathies in ASD reviewing genetic, human cell model, rodent studies and clinical trials. We conclude that signalopathies have an increased liability for ASD and that, in particular, ASD individuals with dysmorphic features and intellectual disability (ID) have a higher chance for disruptive mutations in RAS- and mTOR-related genes. Studies on rodent and human cell models confirm aberrant neuronal development as the underlying pathology. Human studies further suggest that multiple hits are necessary to induce the respective phenotypes. Recent clinical trials do only report improvements for comorbid conditions such as epilepsy or cancer but not for behavioral aspects. Animal models show that treatment during early development can rescue behavioral phenotypes. Taken together, we suggest investigating the differential roles of mTOR and RAS signaling in both human and rodent models, and to test drug treatment both during and after neuronal development in the available model systems.
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Affiliation(s)
- Verica Vasic
- Institute for Microscopic Anatomy and Neurobiology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany; (V.V.); (M.J.S.)
| | - Mattson S. O. Jones
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
| | - Denise Haslinger
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Lisa S. Knaus
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Michael J. Schmeisser
- Institute for Microscopic Anatomy and Neurobiology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany; (V.V.); (M.J.S.)
- Focus Program Translational Neurosciences (FTN), University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany
| | - Gaia Novarino
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Andreas G. Chiocchetti
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
- Correspondence: ; Tel.: +49-69-6301-80658
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26
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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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27
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Loissell-Baltazar YA, Dokudovskaya S. SEA and GATOR 10 Years Later. Cells 2021; 10:cells10102689. [PMID: 34685669 PMCID: PMC8534245 DOI: 10.3390/cells10102689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/30/2021] [Accepted: 10/03/2021] [Indexed: 12/17/2022] Open
Abstract
The SEA complex was described for the first time in yeast Saccharomyces cerevisiae ten years ago, and its human homologue GATOR complex two years later. During the past decade, many advances on the SEA/GATOR biology in different organisms have been made that allowed its role as an essential upstream regulator of the mTORC1 pathway to be defined. In this review, we describe these advances in relation to the identification of multiple functions of the SEA/GATOR complex in nutrient response and beyond and highlight the consequence of GATOR mutations in cancer and neurodegenerative diseases.
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Klofas LK, Short BP, Zhou C, Carson RP. Prevention of premature death and seizures in a Depdc5 mouse epilepsy model through inhibition of mTORC1. Hum Mol Genet 2021; 29:1365-1377. [PMID: 32280987 DOI: 10.1093/hmg/ddaa068] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 03/31/2020] [Accepted: 04/06/2020] [Indexed: 11/13/2022] Open
Abstract
Mutations in DEP domain containing 5 (DEPDC5) are increasingly appreciated as one of the most common causes of inherited focal epilepsy. Epilepsies due to DEPDC5 mutations are often associated with brain malformations, tend to be drug-resistant, and have been linked to an increased risk of sudden unexplained death in epilepsy (SUDEP). Generation of epilepsy models to define mechanisms of epileptogenesis remains vital for future therapies. Here, we describe a novel mouse model of Depdc5 deficiency with a severe epilepsy phenotype, generated by conditional deletion of Depdc5 in dorsal telencephalic neuroprogenitor cells. In contrast to control and heterozygous mice, Depdc5-Emx1-Cre conditional knockout (CKO) mice demonstrated macrocephaly, spontaneous seizures and premature death. Consistent with increased mTORC1 activation, targeted neurons were enlarged and both neurons and astrocytes demonstrated increased S6 phosphorylation. Electrophysiologic characterization of miniature inhibitory post-synaptic currents in excitatory neurons was consistent with impaired post-synaptic response to GABAergic input, suggesting a potential mechanism for neuronal hyperexcitability. mTORC1 inhibition with rapamycin significantly improved survival of CKO animals and prevented observed seizures, including for up to 40 days following rapamycin withdrawal. These data not only support a primary role for mTORC1 hyperactivation in epilepsy following homozygous loss of Depdc5, but also suggest a developmental window for treatment which may have a durable benefit for some time even after withdrawal.
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Affiliation(s)
- Lindsay K Klofas
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Brittany P Short
- Division of Pediatric Neurology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Chengwen Zhou
- Department of Neurology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Robert P Carson
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA.,Division of Pediatric Neurology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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29
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Wang T, Zhou M, Zhang Q, Zhang C, Peng G. ubtor Mutation Causes Motor Hyperactivity by Activating mTOR Signaling in Zebrafish. Neurosci Bull 2021; 37:1658-1670. [PMID: 34309811 PMCID: PMC8643380 DOI: 10.1007/s12264-021-00755-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 04/08/2021] [Indexed: 01/20/2023] Open
Abstract
Mechanistic target of rapamycin (mTOR) signaling governs important physiological and pathological processes key to cellular life. Loss of mTOR negative regulators and subsequent over-activation of mTOR signaling are major causes underlying epileptic encephalopathy. Our previous studies showed that UBTOR/KIAA1024/MINAR1 acts as a negative regulator of mTOR signaling, but whether UBTOR plays a role in neurological diseases remains largely unknown. We therefore examined a zebrafish model and found that ubtor disruption caused increased spontaneous embryonic movement and neuronal activity in spinal interneurons, as well as the expected hyperactivation of mTOR signaling in early zebrafish embryos. In addition, mutant ubtor larvae showed increased sensitivity to the convulsant pentylenetetrazol, and both the motor activity and the neuronal activity were up-regulated. These phenotypic abnormalities in zebrafish embryos and larvae were rescued by treatment with the mTORC1 inhibitor rapamycin. Taken together, our findings show that ubtor regulates motor hyperactivity and epilepsy-like behaviors by elevating neuronal activity and activating mTOR signaling.
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Affiliation(s)
- Tiantian Wang
- State Key Laboratory of Medical Neurobiology, Ministry of Education Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Mingshan Zhou
- State Key Laboratory of Medical Neurobiology, Ministry of Education Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Quan Zhang
- State Key Laboratory of Medical Neurobiology, Ministry of Education Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Cuizhen Zhang
- State Key Laboratory of Medical Neurobiology, Ministry of Education Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Gang Peng
- State Key Laboratory of Medical Neurobiology, Ministry of Education Frontiers Center for Brain Science, and Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
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30
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Koh HY, Jang J, Ju SH, Kim R, Cho GB, Kim DS, Sohn JW, Paik SB, Lee JH. Non-Cell Autonomous Epileptogenesis in Focal Cortical Dysplasia. Ann Neurol 2021; 90:285-299. [PMID: 34180075 DOI: 10.1002/ana.26149] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Low-level somatic mosaicism in the brain has been shown to be a major genetic cause of intractable focal epilepsy. However, how a relatively few mutation-carrying neurons are able to induce epileptogenesis at the local network level remains poorly understood. METHODS To probe the origin of epileptogenesis, we measured the excitability of neurons with MTOR mutation and nearby nonmutated neurons recorded by whole-cell patch-clamp and array-based electrodes comparing the topographic distribution of mutation. Computational simulation is used to understand neural network-level changes based on electrophysiological properties. To examine the underlying mechanism, we measured inhibitory and excitatory synaptic inputs in mutated neurons and nearby neurons by electrophysiological and histological methods using the mouse model and postoperative human brain tissue for cortical dysplasia. To explain non-cell-autonomous hyperexcitability, an inhibitor of adenosine kinase was injected into mice to enhance adenosine signaling and to mitigate hyperactivity of nearby nonmutated neurons. RESULTS We generated mice with a low-level somatic mutation in MTOR presenting spontaneous seizures. The seizure-triggering hyperexcitability originated from nonmutated neurons near mutation-carrying neurons, which proved to be less excitable than nonmutated neurons. Interestingly, the net balance between excitatory and inhibitory synaptic inputs onto mutated neurons remained unchanged. Additionally, we found that inhibition of adenosine kinase, which affects adenosine metabolism and neuronal excitability, reduced the hyperexcitability of nonmutated neurons. INTERPRETATION This study shows that neurons carrying somatic mutations in MTOR lead to focal epileptogenesis via non-cell-autonomous hyperexcitability of nearby nonmutated neurons. ANN NEUROL 2021;90:285-299.
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Affiliation(s)
- Hyun Yong Koh
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Jaeson Jang
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Sang Hyeon Ju
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Ryunhee Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Gyu-Bon Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Dong Seok Kim
- Department of Neurosurgery, Pediatric Epilepsy Clinics, Brain Korea 21 Project for Medical Science, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jong-Woo Sohn
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Se-Bum Paik
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.,Program of Brain and Cognitive Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Jeong Ho Lee
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea.,SoVarGen, Daejeon, Republic of Korea
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31
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D'Gama AM, Poduri A. Precision Therapy for Epilepsy Related to Brain Malformations. Neurotherapeutics 2021; 18:1548-1563. [PMID: 34608615 PMCID: PMC8608994 DOI: 10.1007/s13311-021-01122-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2021] [Indexed: 02/04/2023] Open
Abstract
Malformations of cortical development (MCDs) represent a range of neurodevelopmental disorders that are collectively common causes of developmental delay and epilepsy, especially refractory childhood epilepsy. Initial treatment with antiseizure medications is empiric, and consideration of surgery is the standard of care for eligible patients with medically refractory epilepsy. In the past decade, advances in next generation sequencing technologies have accelerated progress in understanding the genetic etiologies of MCDs, and precision therapies for focal MCDs are emerging. Notably, mutations that lead to abnormal activation of the mammalian target of rapamycin (mTOR) pathway, which provides critical control of cell growth and proliferation, have emerged as a common cause of malformations. These include tuberous sclerosis complex (TSC), hemimegalencephaly (HME), and some types of focal cortical dysplasia (FCD). TSC currently represents the best example for the pathway from gene discovery to relatively safe and efficacious targeted therapy for epilepsy related to MCDs. Based on extensive pre-clinical and clinical data, the mTOR inhibitor everolimus is currently approved for the treatment of focal refractory seizures in patients with TSC. Although clinical studies are just emerging for FCD and HME, we believe the next decade will bring significant advancements in precision therapies for epilepsy related to these and other MCDs.
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Affiliation(s)
- Alissa M D'Gama
- Divisions of Newborn Medicine and Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
- Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA.
- Broad Institute of Harvard and MIT, Cambridge, MA, USA.
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32
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Yuskaitis CJ, Rossitto L, Groff KJ, Dhamne SC, Zhang B, Lalani LK, Singh AK, Rotenberg A, Sahin M. Factors influencing the acute pentylenetetrazole-induced seizure paradigm and a literature review. Ann Clin Transl Neurol 2021; 8:1388-1397. [PMID: 34102033 PMCID: PMC8283168 DOI: 10.1002/acn3.51375] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/23/2021] [Accepted: 04/14/2021] [Indexed: 01/18/2023] Open
Abstract
OBJECTIVE To confirm the critical factors affecting seizure susceptibility in acute pentylenetetrazole (PTZ) mouse epilepsy models and evaluate the prior literature for these factors. METHODS Serial cohorts of wild-type mice administered intraperitoneal (IP)-PTZ were aggregated and analyzed by multivariate logistic regression for the effect of sex, age, background strain, dose, and physiologic stress (i.e., EEG implantation and/or single-housing) on seizure response. We assessed the reporting of these factors in a comprehensive literature review over the last 10 years (2010-2020). RESULTS We conducted aggregated analysis of pooled data of 307 mice (220 C57BL/6J mice and 87 mixed background mice; 202 males, 105 females) with median age of 10 weeks (range: 6-49 weeks) with acute PTZ injection (dose range 40-65 mg/kg). Significance in multivariate analysis was found between seizures and increased PTZ dose (odds ratio (OR) 1.149, 95% confidence interval (CI) 1.102-1.205), older age (OR 1.1, 95% CI 1.041-1.170), physiologic stress (OR 17.36, 95% CI 7.349-44.48), and mixed background strain (OR 0.4725, 95% CI 0.2315-0.9345). Literature review identified 97 papers using acute PTZ-seizure models. Age, housing, sex, and background were omitted by 61% (59/97), 51% (49/97), 18% (17/97), and 8% (8/97) papers, respectively. Only 17% of publications specified all four factors (16/97). INTERPRETATION Our analysis and literature review demonstrate a critical gap in standardization of acute PTZ-induced seizure paradigm in mice. We recommend that future studies specify and control for age, background strain, sex, and housing conditions of experimental animals.
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Affiliation(s)
- Christopher J. Yuskaitis
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Department of NeurologyBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics ProgramBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
| | - Leigh‐Ana Rossitto
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
| | - Karenna J. Groff
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
| | - Sameer C. Dhamne
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
| | - Bo Zhang
- Department of NeurologyBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Biostatistics and Research Design CenterInstitutional Centers for Clinical and Translational ResearchBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
| | - Lahin K. Lalani
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Rosamund Stone Zander Translational Neuroscience CenterBoston Children’s HospitalBostonMassachusetts02115USA
| | - Achint K. Singh
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Rosamund Stone Zander Translational Neuroscience CenterBoston Children’s HospitalBostonMassachusetts02115USA
| | - Alexander Rotenberg
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Department of NeurologyBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics ProgramBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Neuromodulation ProgramDepartment of NeurologyBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
| | - Mustafa Sahin
- F.M. Kirby Neurobiology CenterBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Department of NeurologyBoston Children’s HospitalHarvard Medical SchoolBostonMassachusetts02115USA
- Rosamund Stone Zander Translational Neuroscience CenterBoston Children’s HospitalBostonMassachusetts02115USA
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33
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Phenotypic analysis of catastrophic childhood epilepsy genes. Commun Biol 2021; 4:680. [PMID: 34083748 PMCID: PMC8175701 DOI: 10.1038/s42003-021-02221-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 05/17/2021] [Indexed: 01/06/2023] Open
Abstract
Genetic engineering techniques have contributed to the now widespread use of zebrafish to investigate gene function, but zebrafish-based human disease studies, and particularly for neurological disorders, are limited. Here we used CRISPR-Cas9 to generate 40 single-gene mutant zebrafish lines representing catastrophic childhood epilepsies. We evaluated larval phenotypes using electrophysiological, behavioral, neuro-anatomical, survival and pharmacological assays. Local field potential recordings (LFP) were used to screen ∼3300 larvae. Phenotypes with unprovoked electrographic seizure activity (i.e., epilepsy) were identified in zebrafish lines for 8 genes; ARX, EEF1A, GABRB3, GRIN1, PNPO, SCN1A, STRADA and STXBP1. We also created an open-source database containing sequencing information, survival curves, behavioral profiles and representative electrophysiology data. We offer all zebrafish lines as a resource to the neuroscience community and envision them as a starting point for further functional analysis and/or identification of new therapies. Griffin et al used CRISPR-Cas9 to generate 40 single-gene mutant zebrafish lines representing childhood epilepsies for which they evaluated larval phenotypes using electrophysiological, behavioral, neuro-anatomical, survival and pharmacological assays. Their study provides a useful resource for the future functional analysis and/or identification of potential anti-epileptic therapies.
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34
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Weston M. Getting Sucker Punched by Depdc5 Really Hurts. Epilepsy Curr 2021; 20:378-380. [PMID: 34025259 PMCID: PMC7818211 DOI: 10.1177/1535759720956992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
[Box: see text]
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35
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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: 29] [Impact Index Per Article: 9.7] [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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36
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Salomone G, Comella M, Portale A, Pecora G, Costanza G, Lo Bianco M, Sciuto S, Praticò ER, Falsaperla R. The Spectrum of DEPDC5-Related Epilepsy. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1727139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractDisheveled EGL-10 and pleckstrin domain-containing protein 5 (DEPDC5) is a key member of the GAP activity toward rags complex 1 complex, which inhibits the mammalian target of rapamycin complex 1 (mTORC1) pathway. DEPDC5 loss-of-function mutations lead to an aberrant activation of the mTOR signaling. At neuronal level, the increased mTOR cascade causes the generation of epileptogenic dysplastic neuronal circuits and it is often associated with malformation of cortical development. The DEPDC5 phenotypic spectrum ranges from sporadic early-onset epilepsies with poor neurodevelopmental outcomes to familial focal epilepsies and sudden unexpected death in epilepsy; a high rate of inter- and intrafamilial variability has been reported. To date, clear genotype–phenotype correlations have not been proven. More studies are required to elucidate the significance of likely pathogenic/variants of uncertain significance. The pursuit of a molecular targeted antiepileptic therapy is a future challenge.
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Affiliation(s)
- Giulia Salomone
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Mattia Comella
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Anna Portale
- Unit of Pediatrics, Avola Hospital, Siracusa, Italy
| | - Giulia Pecora
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Giuseppe Costanza
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Manuela Lo Bianco
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Sarah Sciuto
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | | | - Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
- Units of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
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37
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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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38
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[Role and mechanism of histone deacetylases in mouse neuronal development]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2021. [PMID: 33691925 PMCID: PMC7969194 DOI: 10.7499/j.issn.1008-8830.2011098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To study the role and mechanism of histone deacetylase 1 (HDAC1) and histone deacetylase 2 (HDAC2) in mouse neuronal development. METHODS The mice with Synapsin1-Cre recombinase were bred with HDAC1&2flox/flox mice to obtain the mice with neuron-specific HDAC1&2 conditional knockout (knockout group), and their littermates without HDAC1&2 knockout were used as the control group. The general status of the mice was observed and survival curves were plotted. Brain tissue samples were collected from the knockout group and the control group. Western blot and immunohistochemistry were used to measure the protein expression of related neuronal and axonal markers, neuronal nuclear antigen (NeuN), non-phosphorylated neurofilament heavy chain (np-NF200), and phosphorylated neurofilament heavy chain (p-NF200), as well as the downstream effector of the mTOR signaling pathway, phosphorylated S6 ribosomal protein (p-S6). RESULTS The mice with HDAC1&2 conditional knockout usually died within one month after birth and were significantly smaller than those in the control group, with motor function abnormalities such as tremor and clasping of hindlimbs. Compared with the control group, the knockout group had significant reductions in the protein expression levels of NeuN, np-NF200, p-NF200, and p-S6 (P < 0.05; n=3). CONCLUSIONS Deletion of HDAC1 and HDAC2 in mouse neurons results in reduced neuronal maturation and axonal dysplasia, which may be associated with the mTOR signaling pathway.
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39
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Hu S, Yang T, Wang Y. Widespread labeling and genomic editing of the fetal central nervous system by in utero CRISPR AAV9-PHP.eB administration. Development 2021; 148:dev.195586. [PMID: 33334860 PMCID: PMC7847274 DOI: 10.1242/dev.195586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/07/2020] [Indexed: 01/20/2023]
Abstract
Efficient genetic manipulation in the developing central nervous system is crucial for investigating mechanisms of neurodevelopmental disorders and the development of promising therapeutics. Common approaches including transgenic mice and in utero electroporation, although powerful in many aspects, have their own limitations. In this study, we delivered vectors based on the AAV9.PHP.eB pseudo-type to the fetal mouse brain, and achieved widespread and extensive transduction of neural cells. When AAV9.PHP.eB-coding gRNA targeting PogZ or Depdc5 was delivered to Cas9 transgenic mice, widespread gene knockout was also achieved at the whole brain level. Our studies provide a useful platform for studying brain development and devising genetic intervention for severe developmental diseases. Summary:In utero CRISPR AAV9-PHP.eB provides a powerful platform to efficiently manipulate gene expression in the developing CNS to investigate mechanisms of neurodevelopmental disorders.
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Affiliation(s)
- Shuntong Hu
- Department of Neurology, The Third Xiangya Hospital, Central South University, Changsha 410013, China.,Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Tao Yang
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yu Wang
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
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40
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Kakizaki T, Ohshiro T, Itakura M, Konno K, Watanabe M, Mushiake H, Yanagawa Y. Rats deficient in the GAD65 isoform exhibit epilepsy and premature lethality. FASEB J 2020; 35:e21224. [PMID: 33236473 DOI: 10.1096/fj.202001935r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/27/2020] [Accepted: 11/11/2020] [Indexed: 02/02/2023]
Abstract
GABA is synthesized by glutamate decarboxylase (GAD), which has two isoforms, namely, GAD65 and GAD67, encoded by the Gad2 and Gad1 genes, respectively. GAD65-deficient (Gad2-/- ) mice exhibit a reduction in brain GABA content after 1 month of age and show spontaneous seizures in adulthood. Approximately 25% of Gad2-/- mice died by 6 months of age. Our Western blot analysis demonstrated that the protein expression ratio of GAD65 to GAD67 in the brain was greater in rats than in mice during postnatal development, suggesting that the contribution of each GAD isoform to GABA functions differs between these two species. To evaluate whether GAD65 deficiency causes different phenotypes between rats and mice, we generated Gad2-/- rats using TALEN genome editing technology. Western blot and immunohistochemical analyses with new antibodies demonstrated that the GAD65 protein was undetectable in the Gad2-/- rat brain. Gad2-/- pups exhibited spontaneous seizures and paroxysmal discharge in EEG at postnatal weeks 3-4. More than 80% of the Gad2-/- rats died at postnatal days (PNDs) 17-23. GABA content in Gad2-/- brains was significantly lower than those in Gad2+/- and Gad2+/+ brains at PND17-19. These results suggest that the low levels of brain GABA content in Gad2-/- rats may lead to epilepsy followed by premature death, and that Gad2-/- rats are more severely affected than Gad2-/- mice. Considering that the GAD65/GAD67 ratio in human brains is more similar to that in rat brains than in mouse brains, Gad2-/- rats would be useful for further investigating the roles of GAD65 in vivo.
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Affiliation(s)
- Toshikazu Kakizaki
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Tomokazu Ohshiro
- Department of Physiology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Makoto Itakura
- Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Japan
| | - Kohtarou Konno
- Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Hajime Mushiake
- Department of Physiology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
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41
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Nicotinic Receptors in Sleep-Related Hypermotor Epilepsy: Pathophysiology and Pharmacology. Brain Sci 2020; 10:brainsci10120907. [PMID: 33255633 PMCID: PMC7761363 DOI: 10.3390/brainsci10120907] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/19/2020] [Accepted: 11/21/2020] [Indexed: 12/12/2022] Open
Abstract
Sleep-related hypermotor epilepsy (SHE) is characterized by hyperkinetic focal seizures, mainly arising in the neocortex during non-rapid eye movements (NREM) sleep. The familial form is autosomal dominant SHE (ADSHE), which can be caused by mutations in genes encoding subunits of the neuronal nicotinic acetylcholine receptor (nAChR), Na+-gated K+ channels, as well as non-channel signaling proteins, such as components of the gap activity toward rags 1 (GATOR1) macromolecular complex. The causative genes may have different roles in developing and mature brains. Under this respect, nicotinic receptors are paradigmatic, as different pathophysiological roles are exerted by distinct nAChR subunits in adult and developing brains. The widest evidence concerns α4 and β2 subunits. These participate in heteromeric nAChRs that are major modulators of excitability in mature neocortical circuits as well as regulate postnatal synaptogenesis. However, growing evidence implicates mutant α2 subunits in ADSHE, which poses interpretive difficulties as very little is known about the function of α2-containing (α2*) nAChRs in the human brain. Planning rational therapy must consider that pharmacological treatment could have different effects on synaptic maturation and adult excitability. We discuss recent attempts towards precision medicine in the mature brain and possible approaches to target developmental stages. These issues have general relevance in epilepsy treatment, as the pathogenesis of genetic epilepsies is increasingly recognized to involve developmental alterations.
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42
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Castello MA, Gleeson JG. Insight into developmental mechanisms of global and focal migration disorders of cortical development. Curr Opin Neurobiol 2020; 66:77-84. [PMID: 33099181 DOI: 10.1016/j.conb.2020.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 10/02/2020] [Accepted: 10/05/2020] [Indexed: 12/20/2022]
Abstract
Cortical development involves neurogenesis followed by migration, maturation, and myelination of immature neurons. Disruptions in these processes can cause malformations of cortical development (MCD). Radial glia (RG) are the stem cells of the brain, both generating neurons and providing the scaffold upon which immature neurons radially migrate. Germline mutations in genes required for cell migration, or cell-cell contact, often lead to global MCDs. Somatic mutations in RG in genes involved in homeostatic function, like mTOR signaling, often lead to focal MCDs. Two different mutations occurring in the same patient can combine in ways we are just beginning to understand. Our growing knowledge about MCD suggests mTOR inhibitors may have expanded utility in treatment-resistant epilepsy, while imaging techniques can better delineate the type and extent of these lesions.
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Affiliation(s)
- Michael A Castello
- Department of Neurosciences, Division of Child Neurology, University of California San Diego, San Diego, CA, USA
| | - Joseph G Gleeson
- Department of Neurosciences, Rady Children's Institute for Genomic Medicine, University of California San Diego, San Diego, CA, USA.
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43
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Klofas LK, Short BP, Snow JP, Sinnaeve J, Rushing GV, Westlake G, Weinstein W, Ihrie RA, Ess KC, Carson RP. DEPDC5 haploinsufficiency drives increased mTORC1 signaling and abnormal morphology in human iPSC-derived cortical neurons. Neurobiol Dis 2020; 143:104975. [PMID: 32574724 PMCID: PMC7462127 DOI: 10.1016/j.nbd.2020.104975] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 05/21/2020] [Accepted: 06/13/2020] [Indexed: 01/21/2023] Open
Abstract
Mutations in the DEPDC5 gene can cause epilepsy, including forms with and without brain malformations. The goal of this study was to investigate the contribution of DEPDC5 gene dosage to the underlying neuropathology of DEPDC5-related epilepsies. We generated induced pluripotent stem cells (iPSCs) from epilepsy patients harboring heterozygous loss of function mutations in DEPDC5. Patient iPSCs displayed increases in both phosphorylation of ribosomal protein S6 and proliferation rate, consistent with elevated mTORC1 activation. In line with these findings, we observed increased soma size in patient iPSC-derived cortical neurons that was rescued with rapamycin treatment. These data indicate that human cells heterozygous for DEPDC5 loss-of-function mutations are haploinsufficient for control of mTORC1 signaling. Our findings suggest that human pathology differs from mouse models of DEPDC5-related epilepsies, which do not show consistent phenotypic differences in heterozygous neurons, and support the need for human-based models to affirm and augment the findings from animal models of DEPDC5-related epilepsy.
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Affiliation(s)
- Lindsay K Klofas
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Brittany P Short
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John P Snow
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Justine Sinnaeve
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | | | - Grant Westlake
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Will Weinstein
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Rebecca A Ihrie
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kevin C Ess
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Robert P Carson
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA.
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44
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MacMullin P, Hodgson N, Damar U, Lee HHC, Hameed MQ, Dhamne SC, Hyde D, Conley GM, Morriss N, Qiu J, Mannix R, Hensch TK, Rotenberg A. Increase in Seizure Susceptibility After Repetitive Concussion Results from Oxidative Stress, Parvalbumin-Positive Interneuron Dysfunction and Biphasic Increases in Glutamate/GABA Ratio. Cereb Cortex 2020; 30:6108-6120. [PMID: 32676666 DOI: 10.1093/cercor/bhaa157] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/29/2020] [Accepted: 05/18/2020] [Indexed: 12/13/2022] Open
Abstract
Chronic symptoms indicating excess cortical excitability follow mild traumatic brain injury, particularly repetitive mild traumatic brain injury (rmTBI). Yet mechanisms underlying post-traumatic excitation/inhibition (E/I) ratio abnormalities may differ between the early and late post-traumatic phases. We therefore measured seizure threshold and cortical gamma-aminobutyric acid (GABA) and glutamate (Glu) concentrations, 1 and 6 weeks after rmTBI in mice. We also analyzed the structure of parvalbumin-positive interneurons (PVIs), their perineuronal nets (PNNs), and their electroencephalography (EEG) signature (gamma frequency band power). For mechanistic insight, we measured cortical oxidative stress, reflected in the reduced/oxidized glutathione (GSH/GSSG) ratio. We found that seizure susceptibility increased both early and late after rmTBI. However, whereas increased Glu dominated the E/I 1 week after rmTBI, Glu concentration normalized and the E/I was instead characterized by depressed GABA, reduced per-PVI parvalbumin expression, and reduced gamma EEG power at the 6-week post-rmTBI time point. Oxidative stress was increased early after rmTBI, where transient PNN degradation was noted, and progressed throughout the monitoring period. We conclude that GSH depletion, perhaps triggered by early Glu-mediated excitotoxicity, leads to late post-rmTBI loss of PVI-dependent cortical inhibitory tone. We thus propose dampening of Glu signaling, maintenance of redox state, and preservation of PVI inhibitory capacity as therapeutic targets for post-rmTBI treatment.
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Affiliation(s)
| | | | - Ugur Damar
- F.M. Kirby Neurobiology Center, Department of Neurology
| | | | - Mustafa Q Hameed
- F.M. Kirby Neurobiology Center, Department of Neurology.,Department of Neurosurgery
| | | | - Damon Hyde
- F.M. Kirby Neurobiology Center, Department of Neurology
| | - Grace M Conley
- Department of Emergency Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Nicholas Morriss
- Department of Emergency Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jianhua Qiu
- Department of Emergency Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Rebekah Mannix
- Department of Emergency Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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45
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Dawud LM, Loetz EC, Lloyd B, Beam R, Tran S, Cowie K, Browne K, Khan T, Montoya R, Greenwood BN, Bland ST. A novel social fear conditioning procedure alters social behavior and mTOR signaling in differentially housed adolescent rats. Dev Psychobiol 2020; 63:74-87. [PMID: 32524583 DOI: 10.1002/dev.22001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 04/07/2020] [Accepted: 04/30/2020] [Indexed: 11/05/2022]
Abstract
Vulnerabilities to fear-related disorders can be enhanced following early life adversity. This study sought to determine whether post-weaning social isolation (PSI), an animal model of early life adversity, alters the development of social fear in an innovative model of conditioned social fear. Male and female Sprague-Dawley rats underwent either social rearing (SR) or PSI for 4 weeks following weaning. Rats were then assigned to groups consisting of either Footshock only, Social conditioned stimulus (CS) only, or Paired footshock with a social CS. Social behavior was assessed the next day. We observed a novel behavioral response in PSI rats, running in circles, that was rarely observed in SR rats; moreover, this behavior was augmented after Paired treatment in PSI rats. Other social behaviors were altered by both PSI and Paired footshock and social CS. The mammalian target of rapamycin (mTOR) pathway was assessed using immunohistochemistry for phosphorylated ribosomal protein S6 (pS6) in subregions of the prefrontal cortex (PFC) and amygdala. Paired treatment produced opposite effects in the PFC and amygdala in males, but no differences were observed in females. Conditioned social fear produced alterations in social behavior and the mTOR pathway that are dependent upon rearing condition and sex.
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Affiliation(s)
- Lamya'a M Dawud
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Esteban C Loetz
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
| | - Brian Lloyd
- Department of Pharmacology, University of Colorado Anschutz Medical School, Aurora, CO, USA
| | - Rachel Beam
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Simon Tran
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Kim Cowie
- Department of Neuroscience, Children's Hospital Colorado, Aurora, CO, USA
| | - Kim Browne
- Department of Inflammation and Immunity, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA
| | - Tassawwar Khan
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Richard Montoya
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
| | | | - Sondra T Bland
- Department of Psychology, University of Colorado Denver, Denver, CO, USA
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46
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Neurodevelopmental Disorders: From Genetics to Functional Pathways. Trends Neurosci 2020; 43:608-621. [PMID: 32507511 DOI: 10.1016/j.tins.2020.05.004] [Citation(s) in RCA: 224] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/27/2020] [Accepted: 05/18/2020] [Indexed: 12/21/2022]
Abstract
Neurodevelopmental disorders (NDDs) are a class of disorders affecting brain development and function and are characterized by wide genetic and clinical variability. In this review, we discuss the multiple factors that influence the clinical presentation of NDDs, with particular attention to gene vulnerability, mutational load, and the two-hit model. Despite the complex architecture of mutational events associated with NDDs, the various proteins involved appear to converge on common pathways, such as synaptic plasticity/function, chromatin remodelers and the mammalian target of rapamycin (mTOR) pathway. A thorough understanding of the mechanisms behind these pathways will hopefully lead to the identification of candidates that could be targeted for treatment approaches.
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47
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Liu GY, Sabatini DM. mTOR at the nexus of nutrition, growth, ageing and disease. Nat Rev Mol Cell Biol 2020; 21:183-203. [PMID: 31937935 PMCID: PMC7102936 DOI: 10.1038/s41580-019-0199-y] [Citation(s) in RCA: 1296] [Impact Index Per Article: 324.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2019] [Indexed: 12/21/2022]
Abstract
The mTOR pathway integrates a diverse set of environmental cues, such as growth factor signals and nutritional status, to direct eukaryotic cell growth. Over the past two and a half decades, mapping of the mTOR signalling landscape has revealed that mTOR controls biomass accumulation and metabolism by modulating key cellular processes, including protein synthesis and autophagy. Given the pathway's central role in maintaining cellular and physiological homeostasis, dysregulation of mTOR signalling has been implicated in metabolic disorders, neurodegeneration, cancer and ageing. In this Review, we highlight recent advances in our understanding of the complex regulation of the mTOR pathway and discuss its function in the context of physiology, human disease and pharmacological intervention.
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Affiliation(s)
- Grace Y Liu
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute, Cambridge, MA, USA
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Broad Institute, Cambridge, MA, USA.
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA.
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48
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Yuskaitis CJ, Rossitto LA, Gurnani S, Bainbridge E, Poduri A, Sahin M. Chronic mTORC1 inhibition rescues behavioral and biochemical deficits resulting from neuronal Depdc5 loss in mice. Hum Mol Genet 2020; 28:2952-2964. [PMID: 31174205 DOI: 10.1093/hmg/ddz123] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/31/2019] [Accepted: 06/04/2019] [Indexed: 01/05/2023] Open
Abstract
DEPDC5 is now recognized as one of the genes most often implicated in familial/inherited focal epilepsy and brain malformations. Individuals with pathogenic variants in DEPDC5 are at risk for epilepsy, associated neuropsychiatric comorbidities and sudden unexplained death in epilepsy. Depdc5flox/flox-Syn1Cre (Depdc5cc+) neuronal-specific Depdc5 knockout mice exhibit seizures and neuronal mTORC1 hyperactivation. It is not known if Depdc5cc+ mice have a hyperactivity/anxiety phenotype, die early from terminal seizures or whether mTOR inhibitors rescue DEPDC5-related seizures and associated comorbidities. Herein, we report that Depdc5cc+ mice were hyperactive in open-field testing but did not display anxiety-like behaviors on the elevated-plus maze. Unlike many other mTOR-related models, Depdc5cc+ mice had minimal epileptiform activity and rare seizures prior to seizure-induced death, as confirmed by video-EEG monitoring. Treatment with the mTORC1 inhibitor rapamycin starting after 3 weeks of age significantly prolonged the survival of Depdc5cc+ mice and partially rescued the behavioral hyperactivity. Rapamycin decreased the enlarged brain size of Depdc5cc+ mice with corresponding decrease in neuronal soma size. Loss of Depdc5 led to a decrease in the other GATOR1 protein levels (NPRL2 and NPRL3). Rapamycin failed to rescue GATOR1 protein levels but rather rescued downstream mTORC1 hyperactivity as measured by phosphorylation of S6. Collectively, our data provide the first evidence of behavioral alterations in mice with Depdc5 loss and support mTOR inhibition as a rational therapeutic strategy for DEPDC5-related epilepsy in humans.
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Affiliation(s)
- Christopher J Yuskaitis
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA.,Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Boston Children's Hospital, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Leigh-Ana Rossitto
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - Sarika Gurnani
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - Elizabeth Bainbridge
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - Annapurna Poduri
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA.,Division of Epilepsy and Clinical Neurophysiology and Epilepsy Genetics Program, Boston Children's Hospital, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Mustafa Sahin
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
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49
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De Fusco A, Cerullo MS, Marte A, Michetti C, Romei A, Castroflorio E, Baulac S, Benfenati F. Acute knockdown of Depdc5 leads to synaptic defects in mTOR-related epileptogenesis. Neurobiol Dis 2020; 139:104822. [PMID: 32113911 DOI: 10.1016/j.nbd.2020.104822] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/02/2020] [Accepted: 02/26/2020] [Indexed: 12/17/2022] Open
Abstract
DEP-domain containing 5 (DEPDC5) is part of the GATOR1 complex that functions as key inhibitor of the mechanistic target of rapamycin complex 1 (mTORC1). Loss-of-function mutations in DEPDC5 leading to mTOR hyperactivation have been identified as the most common cause of either lesional or non-lesional focal epilepsy. However, the precise mechanisms by which DEPDC5 loss-of-function triggers neuronal and network hyperexcitability are still unclear. In this study, we investigated the cellular mechanisms of hyperexcitability by comparing the constitutive heterozygous Depdc5 knockout mouse versus different levels of acute Depdc5 deletion (≈40% and ≈80% neuronal knockdown of Depdc5 protein) by RNA interference in primary cortical cultures. While heterozygous Depdc5+/- neurons have only a subtle phenotype, acutely knocked-down neurons exhibit a strong dose-dependent phenotype characterized by mTOR hyperactivation, increased soma size, dendritic arborization, excitatory synaptic transmission and intrinsic excitability. The robust synaptic phenotype resulting from the acute knockdown Depdc5 deficiency highlights the importance of the temporal dynamics of Depdc5 knockdown in triggering the phenotypic changes, reminiscent of the somatic second-hit mechanism in patients with focal cortical dysplasia. These findings uncover a novel synaptic phenotype that is causally linked to Depdc5 knockdown, highlighting the developmental role of Depdc5. Interestingly, the synaptic defect appears to affect only excitatory synapses, while inhibitory synapses develop normally. The increased frequency and amplitude of mEPSCs, paralleled by increased density of excitatory synapses and expression of glutamate receptors, may generate an excitation/inhibition imbalance that triggers epileptogenesis.
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Affiliation(s)
- Antonio De Fusco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Maria Sabina Cerullo
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Antonella Marte
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy; IRCSS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Caterina Michetti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; IRCSS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Alessandra Romei
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Enrico Castroflorio
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Stephanie Baulac
- Sorbonne Université, UPMC Univ Paris 06, UMR S 1127, INSERM, U1127, CNRS, UMR 7225, Institut du Cerveau et de la Moelle épinière (ICM), Hôpital Pitié-Salpêtrière, F-75013 Paris, France
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy; IRCSS, Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy.
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50
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Garcia CAB, Carvalho SCS, Yang X, Ball LL, George RD, James KN, Stanley V, Breuss MW, Thomé U, Santos MV, Saggioro FP, Neder Serafini L, Silva WA, Gleeson JG, Machado HR. mTOR pathway somatic variants and the molecular pathogenesis of hemimegalencephaly. Epilepsia Open 2020; 5:97-106. [PMID: 32140648 PMCID: PMC7049797 DOI: 10.1002/epi4.12377] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 12/16/2019] [Accepted: 01/02/2020] [Indexed: 12/28/2022] Open
Abstract
Objectives Recently, defects in the protein kinase mTOR (mammalian target of rapamycin) and its associated pathway have been correlated with hemimegalencephaly (HME). mTOR acts as a central regulator of important physiological cellular functions such as growth and proliferation, metabolism, autophagy, death, and survival. This study was aimed at identifying specific variants in mTOR signaling pathway genes in patients diagnosed with HME. Methods Using amplicon and whole exome sequencing (WES) of resected brain and paired blood samples from five HME patients, we were able to identify pathogenic mosaic variants in the mTOR pathway genes MTOR, PIK3CA, and DEPDC5. Results These results strengthen the hypothesis that somatic variants in PI3K-Akt-mTOR pathway genes contribute to HME. We also describe one patient presenting with a pathogenic variant on DEPDC5 gene, which reinforces the role of DEPDC5 on cortical structural changes due to mTORC1 hyperactivation. These findings also provide insights into when in brain development these variants occurred. An early developmental variant is expected to affect a larger number of cells and to result in a larger malformation, whereas the same variant occurring later in development would cause a minor malformation. Significance In the future, numerous somatic variants in known or new genes will undoubtedly be revealed in resected brain samples, making it possible to draw correlations between genotypes and phenotypes and allow for a genetic clinical diagnosis that may help to predict a given patient's outcome.
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Affiliation(s)
- Camila A B Garcia
- Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Simone C S Carvalho
- Department of Genetics Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Xiaoxu Yang
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Laurel L Ball
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Renee D George
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Kiely N James
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Valentina Stanley
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Martin W Breuss
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Ursula Thomé
- Department of Neurosciences and Behavioral Sciences Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Marcelo V Santos
- Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
| | - Fabiano P Saggioro
- Department of Pathology Ribeirão Preto School of Medicine University of São Paulo USP Ribeirao Preto SP Brazil
| | - Luciano Neder Serafini
- Department of Pathology Ribeirão Preto School of Medicine University of São Paulo USP Ribeirao Preto SP Brazil
| | - Wilson A Silva
- Department of Genetics Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil.,Center for Medical Genomics University Hospital of Ribeirão Preto Medical School (USP) Ribeirao Preto SP Brazil
| | - Joseph G Gleeson
- Laboratory for Pediatric Brain Disease Howard Hughes Medical Institute Department of Neurosciences University of California San Diego, La Jolla CA USA
| | - Hélio R Machado
- Department of Surgery and Anatomy Ribeirão Preto Medical School University of São Paulo (USP) Ribeirao Preto SP Brazil
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