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Falace A, Corbieres L, Palminha C, Guarnieri FC, Schaller F, Buhler E, Tuccari di San Carlo C, Montheil A, Watrin F, Manent JB, Represa A, de Chevigny A, Pallesi-Pocachard E, Cardoso C. FLNA regulates neuronal maturation by modulating RAC1-Cofilin activity in the developing cortex. Neurobiol Dis 2024; 198:106558. [PMID: 38852754 DOI: 10.1016/j.nbd.2024.106558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 06/05/2024] [Accepted: 06/05/2024] [Indexed: 06/11/2024] Open
Abstract
Periventricular nodular heterotopia (PNH), the most common brain malformation diagnosed in adulthood, is characterized by the presence of neuronal nodules along the ventricular walls. PNH is mainly associated with mutations in the FLNA gene - encoding an actin-binding protein - and patients often develop epilepsy. However, the molecular mechanisms underlying the neuronal failure still remain elusive. It has been hypothesized that dysfunctional cortical circuitry, rather than ectopic neurons, may explain the clinical manifestations. To address this issue, we depleted FLNA from cortical pyramidal neurons of a conditional Flnaflox/flox mice by timed in utero electroporation of Cre recombinase. We found that FLNA regulates dendritogenesis and spinogenesis thus promoting an appropriate excitatory/inhibitory inputs balance. We demonstrated that FLNA modulates RAC1 and cofilin activity through its interaction with the Rho-GTPase Activating Protein 24 (ARHGAP24). Collectively, we disclose an uncharacterized role of FLNA and provide strong support for neural circuit dysfunction being a consequence of FLNA mutations.
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Affiliation(s)
- Antonio Falace
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto "Giannina Gaslini", Genova, Italy.
| | - Lea Corbieres
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Catia Palminha
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Fabrizia Claudia Guarnieri
- Institute of Neuroscience, National Research Council (CNR), Vedano al Lambro (MB), Italy; IRCSS San Raffaele Scientific Institute, Milan, Italy
| | - Fabienne Schaller
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Emmanuelle Buhler
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Clara Tuccari di San Carlo
- Pediatric Neurology Unit and Laboratories, IRCCS Meyer Children's Hospital University of Florence, Firenze, Italy
| | - Aurelie Montheil
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France; INMED, INSERM UMR1249, Aix Marseille University, Molecular and Cellular Biology Platform, Parc Scientifique de Luminy, Marseille, France
| | - Françoise Watrin
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Jean Bernard Manent
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Alfonso Represa
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Antoine de Chevigny
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France
| | - Emilie Pallesi-Pocachard
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France; INMED, INSERM UMR1249, Aix Marseille University, Molecular and Cellular Biology Platform, Parc Scientifique de Luminy, Marseille, France
| | - Carlos Cardoso
- INMED, INSERM UMR1249, Aix Marseille University, Parc Scientifique de Luminy, Marseille, France.
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Lieberman S, Rivera DA, Morton R, Hingorani A, Southard TL, Johnson L, Reukauf J, Radwanski RE, Zhao M, Nishimura N, Bracko O, Schwartz TH, Schaffer CB. Circumscribing Laser Cuts Attenuate Seizure Propagation in a Mouse Model of Focal Epilepsy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2300747. [PMID: 38810146 PMCID: PMC11304327 DOI: 10.1002/advs.202300747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/24/2024] [Indexed: 05/31/2024]
Abstract
In partial onset epilepsy, seizures arise focally in the brain and often propagate. Patients frequently become refractory to medical management, leaving neurosurgery, which can cause neurologic deficits, as a primary treatment. In the cortex, focal seizures spread through horizontal connections in layers II/III, suggesting that severing these connections can block seizures while preserving function. Focal neocortical epilepsy is induced in mice, sub-surface cuts are created surrounding the seizure focus using tightly-focused femtosecond laser pulses, and electrophysiological recordings are acquired at multiple locations for 3-12 months. Cuts reduced seizure frequency in most animals by 87%, and only 5% of remaining seizures propagated to the distant electrodes, compared to 80% in control animals. These cuts produced a modest decrease in cortical blood flow that recovered and left a ≈20-µm wide scar with minimal collateral damage. When placed over the motor cortex, cuts do not cause notable deficits in a skilled reaching task, suggesting they hold promise as a novel neurosurgical approach for intractable focal cortical epilepsy.
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Affiliation(s)
- Seth Lieberman
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
- College of Veterinary MedicineCornell UniversityIthacaNY14853USA
| | - Daniel A. Rivera
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
| | - Ryan Morton
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
| | - Amrit Hingorani
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
| | | | - Lynn Johnson
- Statistical Consulting UnitCornell UniversityIthacaNY14853USA
| | - Jennifer Reukauf
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
- College of Veterinary MedicineCornell UniversityIthacaNY14853USA
| | - Ryan E. Radwanski
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
| | - Mingrui Zhao
- Department of Neurological SurgeryWeill Cornell Medicine of Cornell UniversityNew YorkNY10065USA
- Brain and Mind Research InstituteWeill Cornell Medicine of Cornell UniversityNew YorkNY10021USA
| | - Nozomi Nishimura
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
| | - Oliver Bracko
- Department of BiologyThe University of MiamiCoral GablesFL33134USA
| | - Theodore H. Schwartz
- Department of Neurological SurgeryWeill Cornell Medicine of Cornell UniversityNew YorkNY10065USA
- Brain and Mind Research InstituteWeill Cornell Medicine of Cornell UniversityNew YorkNY10021USA
| | - Chris B. Schaffer
- Meinig School of Biomedical EngineeringCornell UniversityIthacaNY14853USA
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Carton RJ, Doyle MG, Kearney H, Steward CA, Lench NJ, Rogers A, Heinzen EL, McDonald S, Fay J, Lacey A, Beausang A, Cryan J, Brett F, El-Naggar H, Widdess-Walsh P, Costello D, Kilbride R, Doherty CP, Sweeney KJ, O'Brien DF, Henshall DC, Delanty N, Cavalleri GL, Benson KA. Somatic variants as a cause of drug-resistant epilepsy including mesial temporal lobe epilepsy with hippocampal sclerosis. Epilepsia 2024; 65:1451-1461. [PMID: 38491957 DOI: 10.1111/epi.17943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 02/14/2024] [Accepted: 02/26/2024] [Indexed: 03/18/2024]
Abstract
OBJECTIVE The contribution of somatic variants to epilepsy has recently been demonstrated, particularly in the etiology of malformations of cortical development. The aim of this study was to determine the diagnostic yield of somatic variants in genes that have been previously associated with a somatic or germline epilepsy model, ascertained from resected brain tissue from patients with multidrug-resistant focal epilepsy. METHODS Forty-two patients were recruited across three categories: (1) malformations of cortical development, (2) mesial temporal lobe epilepsy with hippocampal sclerosis, and (3) nonlesional focal epilepsy. Participants were subdivided based on histopathology of the resected brain. Paired blood- and brain-derived DNA samples were sequenced using high-coverage targeted next generation sequencing to high depth (585× and 1360×, respectively). Variants were identified using Genome Analysis ToolKit (GATK4) MuTect-2 and confirmed using high-coverage Amplicon-EZ sequencing. RESULTS Sequence data on 41 patients passed quality control. Four somatic variants were validated following amplicon sequencing: within CBL, ALG13, MTOR, and FLNA. The diagnostic yield across 41 patients was 10%, 9% in mesial temporal lobe epilepsy with hippocampal sclerosis and 20% in malformations of cortical development. SIGNIFICANCE This study provides novel insights into the etiology of mesial temporal lobe epilepsy with hippocampal sclerosis, highlighting a potential pathogenic role of somatic variants in CBL and ALG13. We also report candidate diagnostic somatic variants in FLNA in focal cortical dysplasia, while providing further insight into the importance of MTOR and related genes in focal cortical dysplasia. This work demonstrates the potential molecular diagnostic value of variants in both germline and somatic epilepsy genes.
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Affiliation(s)
- Robert J Carton
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Michael G Doyle
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
- Strategic Academic Recruitment Doctor of Medicine Programme, Royal College of Surgeons in Ireland in collaboration with Blackrock Clinic, Dublin, Ireland
| | - Hugh Kearney
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | | | | | - Anthony Rogers
- Congenica Limited, BioData Innovation Centre, Cambridge, UK
| | - Erin L Heinzen
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Seamus McDonald
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Joanna Fay
- Royal College of Surgeons in Ireland Biobanking Service, Dublin, Ireland
| | - Austin Lacey
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Alan Beausang
- Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
| | - Jane Cryan
- Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
| | - Francesca Brett
- Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
| | - Hany El-Naggar
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | - Peter Widdess-Walsh
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | - Daniel Costello
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Neurology, Cork University Hospital, Cork, Ireland
| | - Ronan Kilbride
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | - Colin P Doherty
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Department of Neurology, St. James's Hospital, Dublin, Ireland
| | - Kieron J Sweeney
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | - Donncha F O'Brien
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | - David C Henshall
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Norman Delanty
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
- Epilepsy Programme, Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | - Gianpiero L Cavalleri
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Katherine A Benson
- FutureNeuro Science Foundation Ireland Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
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Wang HY, Cecon E, Dam J, Pei Z, Jockers R, Burns LH. Simufilam Reverses Aberrant Receptor Interactions of Filamin A in Alzheimer's Disease. Int J Mol Sci 2023; 24:13927. [PMID: 37762230 PMCID: PMC10531384 DOI: 10.3390/ijms241813927] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/29/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Simufilam is a novel oral drug candidate in Phase 3 clinical trials for Alzheimer's disease (AD) dementia. This small molecule binds an altered form of filamin A (FLNA) that occurs in AD. This drug action disrupts FLNA's aberrant linkage to the α7 nicotinic acetylcholine receptor (α7nAChR), thereby blocking soluble amyloid beta1-42 (Aβ42)'s signaling via α7nAChR that hyperphosphorylates tau. Here, we aimed to clarify simufilam's mechanism. We now show that simufilam reduced Aβ42 binding to α7nAChR with a 10-picomolar IC50 using time-resolved fluorescence resonance energy transfer (TR-FRET), a robust technology to detect highly sensitive molecular interactions. We also show that FLNA links to multiple inflammatory receptors in addition to Toll-like receptor 4 (TLR4) in postmortem human AD brains and in AD transgenic mice: TLR2, C-X-C chemokine receptor type 4 (CXCR4), C-C chemokine receptor type 5 (CCR5), and T-cell co-receptor cluster of differentiation 4 (CD4). These aberrant FLNA linkages, which can be induced in a healthy control brain by Aβ42 incubation, were disrupted by simufilam. Simufilam reduced inflammatory cytokine release from Aβ42-stimulated human astrocytes. In the AD transgenic mice, CCR5-G protein coupling was elevated, indicating persistent activation. Oral simufilam reduced both the FLNA-CCR5 linkage and the CCR5-G protein coupling in these mice, while restoring CCR5's responsivity to C-C chemokine ligand 3 (CCL3). By disrupting aberrant FLNA-receptor interactions critical to AD pathogenic pathways, simufilam may promote brain health.
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Affiliation(s)
- Hoau-Yan Wang
- Department of Molecular, Cellular and Biomedical Sciences, City University of New York School of Medicine, New York, NY 10031, USA; (H.-Y.W.); (Z.P.)
- Department of Biology and Neuroscience, Graduate School, City University of New York, New York, NY 10016, USA
| | - Erika Cecon
- Institut Cochin, INSERM, CNRS, Université Paris Cité, 75014 Paris, France; (E.C.); (J.D.); (R.J.)
| | - Julie Dam
- Institut Cochin, INSERM, CNRS, Université Paris Cité, 75014 Paris, France; (E.C.); (J.D.); (R.J.)
| | - Zhe Pei
- Department of Molecular, Cellular and Biomedical Sciences, City University of New York School of Medicine, New York, NY 10031, USA; (H.-Y.W.); (Z.P.)
| | - Ralf Jockers
- Institut Cochin, INSERM, CNRS, Université Paris Cité, 75014 Paris, France; (E.C.); (J.D.); (R.J.)
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Zhang L, Bordey A. Advances in glioma models using in vivo electroporation to highjack neurodevelopmental processes. Biochim Biophys Acta Rev Cancer 2023; 1878:188951. [PMID: 37433417 DOI: 10.1016/j.bbcan.2023.188951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/13/2023]
Abstract
Glioma is the most prevalent type of neurological malignancies. Despite decades of efforts in neurosurgery, chemotherapy and radiation therapy, glioma remains one of the most treatment-resistant brain tumors with unfavorable outcomes. Recent progresses in genomic and epigenetic profiling have revealed new concepts of genetic events involved in the etiology of gliomas in humans, meanwhile, revolutionary technologies in gene editing and delivery allows to code these genetic "events" in animals to genetically engineer glioma models. This approach models the initiation and progression of gliomas in a natural microenvironment with an intact immune system and facilitates probing therapeutic strategies. In this review, we focus on recent advances in in vivo electroporation-based glioma modeling and outline the established genetically engineered glioma models (GEGMs).
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Affiliation(s)
- Longbo Zhang
- Departments of Neurosurgery, Changde hospital, Xiangya School of Medicine, Central South University, 818 Renmin Street, Wuling District, Changde, Hunan 415003, China; Departments of Neurosurgery, and National Clinical Research Center of Geriatric Disorders, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410008, China; Departments of Neurosurgery, and Cellular & Molecular Physiology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8082, USA.
| | - Angelique Bordey
- Departments of Neurosurgery, and Cellular & Molecular Physiology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8082, USA
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Burns LH, Pei Z, Wang HY. Targeting α7 nicotinic acetylcholine receptors and their protein interactions in Alzheimer's disease drug development. Drug Dev Res 2023; 84:1085-1095. [PMID: 37291958 DOI: 10.1002/ddr.22085] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/09/2023] [Accepted: 05/29/2023] [Indexed: 06/10/2023]
Abstract
The decades-old cholinergic hypothesis of Alzheimer's disease (AD) led to clinical testing and FDA approval of acetylcholinesterase inhibitor drugs. Subsequently, the α7 nicotinic acetylcholine receptor (α7nAChR) was proposed as a new drug target for enhancing cholinergic neurotransmission. Nearly simultaneously, soluble amyloid β1-42 (Aβ42 ) was shown to bind α7nAChR with picomolar affinity to activate kinases that hyperphosphorylate tau, the precursor to tau-containing tangles. Multiple biopharmaceutical companies explored α7nAChR as a drug target for AD, mostly to enhance neurotransmission. Directly targeting α7nAChR proved to be a drug development challenge. The ultra-high-affinity interaction between Aβ42 and α7nAChR posed a significant hurdle for direct competition in the AD brain. The receptor rapidly desensitizes, undermining efficacy of agonists. Drug discovery approaches therefore included partial agonists and allosteric modulators of α7nAChR. After substantial effort, numerous drug candidates were abandoned due to lack of efficacy or drug-related toxicities. As alternatives, proteins interacting with α7nAChR were sought. In 2016, a novel nAChR regulator was identified, but no drug candidates have emerged from this effort. In 2012, the interaction of filamin A with α7nAChR was shown to be critical to Aβ42 's toxic signaling via α7nAChR, presenting a new drug target. The novel drug candidate simufilam disrupts the filamin A-α7nAChR interaction, reduces Aβ42 's high-affinity binding to α7nAChR, and suppresses Aβ42 's toxic signaling. Early clinical trials of simufilam showed improvements in experimental CSF biomarkers and indications of cognitive improvement in mild AD patients at 1 year. Simufilam is currently in phase 3 clinical trials as a disease-modifying treatment for AD.
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Affiliation(s)
| | - Zhe Pei
- Department of Molecular, Cellular and Biomedical Sciences, City University of New York School of Medicine, New York, New York, USA
| | - Hoau-Yan Wang
- Department of Molecular, Cellular and Biomedical Sciences, City University of New York School of Medicine, New York, New York, USA
- Department of Biology and Neuroscience, Graduate School of the City University of New York, New York, New York, USA
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Bordey A. KIF4 Gene Variant's Disruption of PARP1 Signaling Increases Anxiety and Seizure Susceptibility. Epilepsy Curr 2023; 23:257-258. [PMID: 37662464 PMCID: PMC10470092 DOI: 10.1177/15357597231175007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023] Open
Abstract
KIF4 Regulates Neuronal Morphology and Seizure Susceptibility via the PARP1 Signaling Pathway Wan Y, Morikawa M, Morikawa M, Iwata S, Naseer MI, Chaudhary AGA, Tanaka Y, Hirokawa N. J Cell Biol . 2023;222(2):e202208108. doi:10.1083/jcb.202208108 Epilepsy is a common neurological disease worldwide, and one of its causes is genetic abnormalities. Here, we identified a point mutation in KIF4A, a member of kinesin superfamily molecular motors, in patients with neurological disorders such as epilepsy, developmental delay, and intellectual disability. KIF4 is involved in the poly (ADP-ribose) polymerase (PARP) signaling pathway, and the mutation (R728Q) strengthened its affinity with PARP1 through elongation of the KIF4 coiled-coil domain. Behavioral tests showed that KIF4-mutant mice exhibited mild developmental delay with lower seizure threshold. Further experiments revealed that the KIF4 mutation caused aberrant morphology in dendrites and spines of hippocampal pyramidal neurons through PARP1-TrkB-KCC2 pathway. Furthermore, supplementing NAD, which activates PARP1, could modulate the TrkB-KCC2 pathway and rescue the seizure susceptibility phenotype of the mutant mice. Therefore, these findings indicate that KIF4 is engaged in a fundamental mechanism regulating seizure susceptibility and could be a potential target for epilepsy treatment.
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Affiliation(s)
- Angelique Bordey
- Departments of Neurosurgery, and Cellular & Molecular Physiology, Yale School of Medicine
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mTORC2 Inhibition Improves Morphological Effects of PTEN Loss, But Does Not Correct Synaptic Dysfunction or Prevent Seizures. J Neurosci 2023; 43:827-845. [PMID: 36526374 PMCID: PMC9899090 DOI: 10.1523/jneurosci.1354-22.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/29/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Hyperactivation of PI3K/PTEN-mTOR signaling during neural development is associated with focal cortical dysplasia (FCD), autism, and epilepsy. mTOR can signal through two major hubs, mTORC1 and mTORC2, both of which are hyperactive following PTEN loss of function (LOF). Here, we tested the hypothesis that genetic inactivation of the mTORC2 complex via deletion of Rictor is sufficient to rescue morphologic and electrophysiological abnormalities in the dentate gyrus caused by PTEN loss, as well as generalized seizures. An established, early postnatal mouse model of PTEN loss in male and female mice showed spontaneous seizures that were not prevented by mTORC2 inactivation. This lack of rescue occurred despite the normalization or amelioration of many morphologic and electrophysiological phenotypes. However, increased excitatory connectivity proximal to dentate gyrus granule neuron somas was not normalized by mTORC2 inactivation. Further studies demonstrated that, although mTORC2 inactivation largely rescued the dendritic arbor overgrowth caused by PTEN LOF, it increased synaptic strength and caused additional impairments of presynaptic function. These results suggest that a constrained increase in excitatory connectivity and co-occurring synaptic dysfunction is sufficient to generate seizures downstream of PTEN LOF, even in the absence of characteristic changes in morphologic properties.SIGNIFICANCE STATEMENT Homozygous deletion of the Pten gene in neuronal subpopulations in the mouse serves as a valuable model of epilepsy caused by mTOR hyperactivation. To better understand the physiological mechanisms downstream of Pten loss that cause epilepsy, as well as the therapeutic potential of targeted gene therapies, we tested whether genetic inactivation of the mTORC2 complex could improve the cellular, synaptic, and in vivo effects of Pten loss in the dentate gyrus. We found that mTORC2 inhibition improved or rescued all morphologic effects of Pten loss in the dentate gyrus, but synaptic changes and seizures persisted. These data suggest that synaptic dysfunction can drive epilepsy caused by hyperactivation of PI3K/PTEN-mTOR, and that future therapies should focus on this mechanistic link.
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9
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Focal cortical dysplasia as a cause of epilepsy: The current evidence of associated genes and future therapeutic treatments. INTERDISCIPLINARY NEUROSURGERY 2022. [DOI: 10.1016/j.inat.2022.101635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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10
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Riley VA, Holmberg JC, Sokolov AM, Feliciano DM. Tsc2 shapes olfactory bulb granule cell molecular and morphological characteristics. Front Mol Neurosci 2022; 15:970357. [PMID: 36277492 PMCID: PMC9581303 DOI: 10.3389/fnmol.2022.970357] [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: 06/15/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Tuberous Sclerosis Complex (TSC) is a neurodevelopmental disorder caused by mutations that inactivate TSC1 or TSC2. Hamartin and tuberin are encoded by TSC1 and TSC2 which form a GTPase activating protein heteromer that inhibits the Rheb GTPase from activating a growth promoting protein kinase called mammalian target of rapamycin (mTOR). Growths and lesions occur in the ventricular-subventricular zone (V-SVZ), cortex, olfactory tract, and olfactory bulbs (OB) in TSC. A leading hypothesis is that mutations in inhibitory neural progenitor cells cause brain growths in TSC. OB granule cells (GCs) are GABAergic inhibitory neurons that are generated through infancy by inhibitory progenitor cells along the V-SVZ. Removal of Tsc1 from mouse OB GCs creates cellular phenotypes seen in TSC lesions. However, the role of Tsc2 in OB GC maturation requires clarification. Here, it is demonstrated that conditional loss of Tsc2 alters GC development. A mosaic model of TSC was created by performing neonatal CRE recombinase electroporation into inhibitory V-SVZ progenitors yielded clusters of ectopic cytomegalic neurons with hyperactive mTOR complex 1 (mTORC1) in homozygous Tsc2 mutant but not heterozygous or wild type mice. Similarly, homozygous Tsc2 mutant GC morphology was altered at postnatal days 30 and 60. Tsc2 mutant GCs had hypertrophic dendritic arbors that were established by postnatal day 30. In contrast, loss of Tsc2 from mature GCs had negligible effects on mTORC1, soma size, and dendrite arborization. OB transcriptome profiling revealed a network of significantly differentially expressed genes following loss of Tsc2 during development that altered neural circuitry. These results demonstrate that Tsc2 has a critical role in regulating neural development and shapes inhibitory GC molecular and morphological characteristics.
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Shao Y, Ge Q, Yang J, Wang M, Zhou Y, Guo JX, Zhu M, Shi J, Hu Y, Shen L, Chen Z, Li XM, Zhu JM, Zhang J, Duan S, Chen J. Pathological Networks Involving Dysmorphic Neurons in Type II Focal Cortical Dysplasia. Neurosci Bull 2022; 38:1007-1024. [PMID: 35235180 PMCID: PMC9468210 DOI: 10.1007/s12264-022-00828-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/24/2021] [Indexed: 10/19/2022] Open
Abstract
Focal cortical dysplasia (FCD) is one of the most common causes of drug-resistant epilepsy. Dysmorphic neurons are the major histopathological feature of type II FCD, but their role in seizure genesis in FCD is unclear. Here we performed whole-cell patch-clamp recording and morphological reconstruction of cortical principal neurons in postsurgical brain tissue from drug-resistant epilepsy patients. Quantitative analyses revealed distinct morphological and electrophysiological characteristics of the upper layer dysmorphic neurons in type II FCD, including an enlarged soma, aberrant dendritic arbors, increased current injection for rheobase action potential firing, and reduced action potential firing frequency. Intriguingly, the upper layer dysmorphic neurons received decreased glutamatergic and increased GABAergic synaptic inputs that were coupled with upregulation of the Na+-K+-Cl- cotransporter. In addition, we found a depolarizing shift of the GABA reversal potential in the CamKII-cre::PTENflox/flox mouse model of drug-resistant epilepsy, suggesting that enhanced GABAergic inputs might depolarize dysmorphic neurons. Thus, imbalance of synaptic excitation and inhibition of dysmorphic neurons may contribute to seizure genesis in type II FCD.
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Affiliation(s)
- Yijie Shao
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Department of Neurosurgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Qianqian Ge
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Jiachao Yang
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Mi Wang
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yu Zhou
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Jin-Xin Guo
- The MOE Key Laboratory of Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Mengyue Zhu
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Jiachen Shi
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yiqi Hu
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Li Shen
- The MOE Key Laboratory of Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
- Department of Orthopedic Surgery, School of Medicine, the Second Affiliated Hospital, Zhejiang University, Hangzhou, 310009, China
- Hangzhou Innovation Center, Zhejiang University, Hangzhou, 310058, China
| | - Zhong Chen
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, School of Basic Medical Sciences, Zhejiang University, Hangzhou, 310058, China
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310058, China
| | - Xiao-Ming Li
- Center for Neuroscience and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Center for Brain Science and Brain-Inspired Intelligence, Joint Institute for Genetics and Genome Medicine between, Guangdong Hong Kong Macao Greater Bay Area, Zhejiang University and the University of Toronto, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Jun-Ming Zhu
- Department of Neurosurgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Jianmin Zhang
- Department of Neurosurgery of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China.
| | - Shumin Duan
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China.
| | - Jiadong Chen
- Center for Neuroscience and Department of Neurosurgery of the Second Affiliated Hospital, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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12
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Zeng C, Hu J, Chen F, Huang T, Zhang L. The Coordination of mTOR Signaling and Non-Coding RNA in Regulating Epileptic Neuroinflammation. Front Immunol 2022; 13:924642. [PMID: 35898503 PMCID: PMC9310657 DOI: 10.3389/fimmu.2022.924642] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Epilepsy accounts for a significant proportion of the burden of neurological disorders. Neuroinflammation acting as the inflammatory response to epileptic seizures is characterized by aberrant regulation of inflammatory cells and molecules, and has been regarded as a key process in epilepsy where mTOR signaling serves as a pivotal modulator. Meanwhile, accumulating evidence has revealed that non-coding RNAs (ncRNAs) interfering with mTOR signaling are involved in neuroinflammation and therefore articipate in the development and progression of epilepsy. In this review, we highlight recent advances in the regulation of mTOR on neuroinflammatory cells and mediators, and feature the progresses of the interaction between ncRNAs and mTOR in epileptic neuroinflammation.
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Affiliation(s)
- Chudai Zeng
- Departments of Neurosurgery, and National Clinical Research Center of Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Jason Hu
- Department of Neonatology, Yale School of Medicine, New Haven, CT, United States
| | - Fenghua Chen
- Departments of Neurosurgery, and National Clinical Research Center of Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- *Correspondence: Fenghua Chen, ; Tianxiang Huang, ; Longbo Zhang,
| | - Tianxiang Huang
- Departments of Neurosurgery, and National Clinical Research Center of Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- *Correspondence: Fenghua Chen, ; Tianxiang Huang, ; Longbo Zhang,
| | - Longbo Zhang
- Departments of Neurosurgery, and National Clinical Research Center of Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, United States
- *Correspondence: Fenghua Chen, ; Tianxiang Huang, ; Longbo Zhang,
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13
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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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14
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Wang G, Wu W, Xu Y, Yang Z, Xiao B, Long L. Imaging Genetics in Epilepsy: Current Knowledge and New Perspectives. Front Mol Neurosci 2022; 15:891621. [PMID: 35706428 PMCID: PMC9189397 DOI: 10.3389/fnmol.2022.891621] [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: 03/08/2022] [Accepted: 05/06/2022] [Indexed: 12/11/2022] Open
Abstract
Epilepsy is a neurological network disease with genetics playing a much greater role than was previously appreciated. Unfortunately, the relationship between genetic basis and imaging phenotype is by no means simple. Imaging genetics integrates multidimensional datasets within a unified framework, providing a unique opportunity to pursue a global vision for epilepsy. This review delineates the current knowledge of underlying genetic mechanisms for brain networks in different epilepsy syndromes, particularly from a neural developmental perspective. Further, endophenotypes and their potential value are discussed. Finally, we highlight current challenges and provide perspectives for the future development of imaging genetics in epilepsy.
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Affiliation(s)
- Ge Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Wenyue Wu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- Department of Neurology, The Second Affiliated Hospital of Nanchang University, Jiangxi, China
| | - Yuchen Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- Department of Neurology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhuanyi Yang
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Lili Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
- *Correspondence: Lili Long
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15
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Nguyen LH, Leiser SC, Song D, Brunner D, Roberds SL, Wong M, Bordey A. Inhibition of MEK-ERK signaling reduces seizures in two mouse models of tuberous sclerosis complex. Epilepsy Res 2022; 181:106890. [PMID: 35219048 PMCID: PMC8930622 DOI: 10.1016/j.eplepsyres.2022.106890] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 02/02/2022] [Accepted: 02/17/2022] [Indexed: 12/25/2022]
Abstract
Tuberous sclerosis complex (TSC) is a monogenic disorder characterized by hyperactivation of the mTOR signaling pathway and developmental brain malformations leading to intractable epilepsy. Although treatment with the recently approved mTOR inhibitor, everolimus, results in clinically relevant seizure suppression in up to 40% of TSC patients, seizures remain uncontrolled in a large number of cases, underscoring the need to identify novel treatment targets. The MEK-ERK signaling pathway has been found to be aberrantly activated in TSC and inhibition of MEK-ERK activity independently of mTOR rescued neuronal dendrite overgrowth in mice modeling TSC neuropathology. Here, we evaluated the efficacy of MEK-ERK inhibition on seizures in two mouse models of TSC. We found that treatment with the MEK inhibitor PD0325901 (mirdametinib) significantly reduced seizure activity in both TSC mouse models. These findings support inhibiting MEK-ERK activity as a potential alternative strategy to treat seizures in TSC.
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Affiliation(s)
- Lena H. Nguyen
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA,Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Steven C. Leiser
- Department of Translational EEG, PsychoGenics, Inc., Paramus, NJ, USA
| | - Dekun Song
- Department of Translational EEG, PsychoGenics, Inc., Paramus, NJ, USA
| | | | | | - Michael Wong
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Angelique Bordey
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA; Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.
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16
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Cortical Dysplasia and the mTOR Pathway: How the Study of Human Brain Tissue Has Led to Insights into Epileptogenesis. Int J Mol Sci 2022; 23:ijms23031344. [PMID: 35163267 PMCID: PMC8835853 DOI: 10.3390/ijms23031344] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 02/01/2023] Open
Abstract
Type II focal cortical dysplasia (FCD) is a neuropathological entity characterised by cortical dyslamination with the presence of dysmorphic neurons only (FCDIIA) or the presence of both dysmorphic neurons and balloon cells (FCDIIB). The year 2021 marks the 50th anniversary of the recognition of FCD as a cause of drug resistant epilepsy, and it is now the most common reason for epilepsy surgery. The causes of FCD remained unknown until relatively recently. The study of resected human FCD tissue using novel genomic technologies has led to remarkable advances in understanding the genetic basis of FCD. Mechanistic parallels have emerged between these non-neoplastic lesions and neoplastic disorders of cell growth and differentiation, especially through perturbations of the mammalian target of rapamycin (mTOR) signalling pathway. This narrative review presents the advances through which the aetiology of FCDII has been elucidated in chronological order, from recognition of an association between FCD and the mTOR pathway to the identification of somatic mosaicism within FCD tissue. We discuss the role of a two-hit mechanism, highlight current challenges and future directions in detecting somatic mosaicism in brain and discuss how knowledge of FCD may inform novel precision treatments of these focal epileptogenic malformations of human cortical development.
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17
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Koene LM, Niggl E, Wallaard I, Proietti-Onori M, Rotaru DC, Elgersma Y. Identifying the temporal electrophysiological and molecular changes that contribute to TSC-associated epileptogenesis. JCI Insight 2021; 6:150120. [PMID: 34877936 PMCID: PMC8675202 DOI: 10.1172/jci.insight.150120] [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: 03/31/2021] [Accepted: 10/27/2021] [Indexed: 11/17/2022] Open
Abstract
Tuberous sclerosis complex (TSC), caused by heterozygous mutations in TSC1 or TSC2, frequently results in intractable epilepsy. Here, we made use of an inducible Tsc1-knockout mouse model, allowing us to study electrophysiological and molecular changes of Tsc1-induced epileptogenesis over time. We recorded from pyramidal neurons in the hippocampus and somatosensory cortex (L2/L3) and combined this with an analysis of transcriptome changes during epileptogenesis. Deletion of Tsc1 resulted in hippocampus-specific changes in excitability and adaptation, which emerged before seizure onset and progressed over time. All phenotypes were rescued after early treatment with rapamycin, an mTOR inhibitor. Later in epileptogenesis, we observed a hippocampal increase of excitation-to-inhibition ratio. These cellular changes were accompanied by dramatic transcriptional changes, especially after seizure onset. Most of these changes were rescued upon rapamycin treatment. Of the genes encoding ion channels or belonging to the Gene Ontology term action potential, 27 were differentially expressed just before seizure onset, suggesting a potential driving role in epileptogenesis. Our data highlight the complex changes driving epileptogenesis in TSC, including the changed expression of multiple ion channels. Our study emphasizes inhibition of the TSC/mTOR signaling pathway as a promising therapeutic approach to target epilepsy in patients with TSC.
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18
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Nguyen LH, Xu Y, Mahadeo T, Zhang L, Lin TV, Born HA, Anderson AE, Bordey A. Expression of 4E-BP1 in juvenile mice alleviates mTOR-induced neuronal dysfunction and epilepsy. Brain 2021; 145:1310-1325. [PMID: 34849602 DOI: 10.1093/brain/awab390] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/01/2021] [Accepted: 09/22/2021] [Indexed: 11/13/2022] Open
Abstract
Hyperactivation of the mechanistic target of rapamycin (mTOR) pathway during fetal neurodevelopment alters neuron structure and function, leading to focal malformation of cortical development (FMCD) and intractable epilepsy. Recent evidence suggests a role for dysregulated cap-dependent translation downstream of mTOR in the formation of FMCD and seizures. However, it is unknown whether modifying translation once the developmental pathologies are established can reverse neuronal abnormalities and seizures. Addressing these issues is crucial with regards to therapeutics since these neurodevelopmental disorders are predominantly diagnosed during childhood, when patients present with symptoms. Here, we report increased phosphorylation of the mTOR effector and translational repressor, 4E-BP1, in patient FMCD tissue and in a mouse model of FMCD. Using temporally regulated conditional gene expression systems, we found that expression of a constitutively active form of 4E-BP1 that resists phosphorylation by mTOR in juvenile mice reduced neuronal cytomegaly and corrected several neuronal electrophysiological alterations, including depolarized resting membrane potential, irregular firing pattern, and aberrant expression of HCN4 channels. Further, 4E-BP1 expression in juvenile FMCD mice after epilepsy onset resulted in improved cortical spectral activity and decreased spontaneous seizure frequency in adults. Overall, our study uncovered a remarkable plasticity of the juvenile brain that facilitates novel therapeutic opportunities to treat FMCD-related epilepsy during childhood with potentially long-lasting effects in adults.
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Affiliation(s)
- Lena H Nguyen
- Department of Neurosurgery, Yale University School of Medicine; New Haven, CT 06510, USA.,Department of Cellular and Molecular Physiology, Yale University School of Medicine; New Haven, CT 06510, USA
| | - Youfen Xu
- Department of Neurosurgery, Yale University School of Medicine; New Haven, CT 06510, USA
| | - Travorn Mahadeo
- Department of Neurosurgery, Yale University School of Medicine; New Haven, CT 06510, USA
| | - Longbo Zhang
- Department of Neurosurgery, Yale University School of Medicine; New Haven, CT 06510, USA
| | - Tiffany V Lin
- Department of Neurosurgery, Yale University School of Medicine; New Haven, CT 06510, USA
| | - Heather A Born
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital; Houston, TX 77030, USA.,Department of Pediatrics, Baylor College of Medicine; Houston, TX 77030, USA
| | - Anne E Anderson
- Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital; Houston, TX 77030, USA.,Department of Pediatrics, Baylor College of Medicine; Houston, TX 77030, USA
| | - Angélique Bordey
- Department of Neurosurgery, Yale University School of Medicine; New Haven, CT 06510, USA.,Department of Cellular and Molecular Physiology, Yale University School of Medicine; New Haven, CT 06510, USA
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19
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Nguyen LH, Bordey A. Corrigendum: Convergent and Divergent Mechanisms of Epileptogenesis in mTORopathies. Front Neuroanat 2021; 15:715363. [PMID: 34295225 PMCID: PMC8290855 DOI: 10.3389/fnana.2021.715363] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 01/16/2023] Open
Affiliation(s)
- Lena H Nguyen
- Department of Neurosurgery, Yale School of Medicine, Yale University, New Haven, CT, United States.,Department of Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Angélique Bordey
- Department of Neurosurgery, Yale School of Medicine, Yale University, New Haven, CT, United States.,Department of Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT, United States
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20
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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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21
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Wang T, Zhang Y, Liu L, Wang Y, Chen H, Fan T, Li J, Xia K, Sun Z. Targeted sequencing and integrative analysis of 3,195 Chinese patients with neurodevelopmental disorders prioritized 26 novel candidate genes. J Genet Genomics 2021; 48:312-323. [PMID: 33994118 DOI: 10.1016/j.jgg.2021.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/05/2021] [Accepted: 03/07/2021] [Indexed: 02/06/2023]
Abstract
Neurodevelopmental disorders (NDDs) are a set of complex disorders characterized by diverse and co-occurring clinical symptoms. The genetic contribution in patients with NDDs remains largely unknown. Here, we sequence 519 NDD-related genes in 3,195 Chinese probands with neurodevelopmental phenotypes and identify 2,522 putative functional mutations consisting of 137 de novo mutations (DNMs) in 86 genes and 2,385 rare inherited mutations (RIMs) with 22 X-linked hemizygotes in 13 genes, 2 homozygous mutations in 2 genes and 23 compound heterozygous mutations in 10 genes. Furthermore, the DNMs of 16,807 probands with NDDs are retrieved from public datasets and combine in an integrated analysis with the mutation data of our Chinese NDD probands by taking 3,582 in-house controls of Chinese origin as background. We prioritize 26 novel candidate genes. Notably, six of these genes - ITSN1, UBR3, CADM1, RYR3, FLNA, and PLXNA3 - preferably contribute to autism spectrum disorders (ASDs), as demonstrated by high co-expression and/or interaction with ASD genes confirmed via rescue experiments in a mouse model. Importantly, these genes are differentially expressed in the ASD cortex in a significant manner and involved in ASD-associated networks. Together, our study expands the genetic spectrum of Chinese NDDs, further facilitating both basic and translational research.
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Affiliation(s)
- Tao Wang
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410083, China; Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; DIAGenes Precision Medicine, Beijing 102600, China
| | - Yi Zhang
- National Clinical Research Centre for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410083, China
| | - Liqui Liu
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan Wang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Huiqian Chen
- Shanghai Adeptus Biotechnology, Shanghai 200126, China
| | - Tianda Fan
- Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Jinchen Li
- National Clinical Research Centre for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410083, China; Department of Neurology, Xiangya Hospital, Central South University, Changsha Hunan, 410083, China.
| | - Kun Xia
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410083, China; CAS Center for Excellence in Brain Science and Intelligences Technology (CEBSIT), Shanghai 200031, China; School of Basic Medical Science, Central South University, Changsha, Hunan, 410083, China.
| | - Zhongsheng Sun
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China; Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China; State Key Laboratory of Integrated Management of Pest Insects and Rodents, Chinese Academy of Sciences, Beijing 100101, China.
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22
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Zhou J, Kang X, An H, Lv Y, Liu X. The function and pathogenic mechanism of filamin A. Gene 2021; 784:145575. [PMID: 33737122 DOI: 10.1016/j.gene.2021.145575] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/13/2022]
Abstract
Filamin A(FLNa) is an actin-binding protein, which participates in the formation of the cytoskeleton, anchors a variety of proteins in the cytoskeleton and regulates cell adhesion and migration. It is involved in signal transduction, cell proliferation and differentiation, pseudopodia formation, vesicle transport, tumor resistance and genetic diseases by binding with interacting proteins. In order to fully elucidate the structure, function and pathogenesis of FLNa, we summarized all substances which directly or indirectly act on FLNa so far, upstream and downstream targets which having effect on it, signaling pathways and their functions. It also recorded the expression and effect of FLNa in different diseases, including hereditary disease and tumors.
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Affiliation(s)
- Jie Zhou
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xinmei Kang
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Hanxiang An
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Yun Lv
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xin Liu
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
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23
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Toniolo S, Sen A, Husain M. Modulation of Brain Hyperexcitability: Potential New Therapeutic Approaches in Alzheimer's Disease. Int J Mol Sci 2020; 21:E9318. [PMID: 33297460 PMCID: PMC7730926 DOI: 10.3390/ijms21239318] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/30/2020] [Accepted: 12/05/2020] [Indexed: 12/12/2022] Open
Abstract
People with Alzheimer's disease (AD) have significantly higher rates of subclinical and overt epileptiform activity. In animal models, oligomeric Aβ amyloid is able to induce neuronal hyperexcitability even in the early phases of the disease. Such aberrant activity subsequently leads to downstream accumulation of toxic proteins, and ultimately to further neurodegeneration and neuronal silencing mediated by concomitant tau accumulation. Several neurotransmitters participate in the initial hyperexcitable state, with increased synaptic glutamatergic tone and decreased GABAergic inhibition. These changes appear to activate excitotoxic pathways and, ultimately, cause reduced long-term potentiation, increased long-term depression, and increased GABAergic inhibitory remodelling at the network level. Brain hyperexcitability has therefore been identified as a potential target for therapeutic interventions aimed at enhancing cognition, and, possibly, disease modification in the longer term. Clinical trials are ongoing to evaluate the potential efficacy in targeting hyperexcitability in AD, with levetiracetam showing some encouraging effects. Newer compounds and techniques, such as gene editing via viral vectors or brain stimulation, also show promise. Diagnostic challenges include identifying best biomarkers for measuring sub-clinical epileptiform discharges. Determining the timing of any intervention is critical and future trials will need to carefully stratify participants with respect to the phase of disease pathology.
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Affiliation(s)
- Sofia Toniolo
- Cognitive Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK;
- Wellcome Trust Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX2 6AE, UK
| | - Arjune Sen
- Oxford Epilepsy Research Group, Nuffield Department Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK;
| | - Masud Husain
- Cognitive Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK;
- Wellcome Trust Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX2 6AE, UK
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24
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Gross C. Fil-lamin-ing in the Gap in Cortical Dysplasia. Epilepsy Curr 2020; 21:51-53. [PMID: 34025274 PMCID: PMC7863307 DOI: 10.1177/1535759720975741] [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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25
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Hsieh LS, Wen JH, Nguyen LH, Zhang L, Getz S, Torres-Reveron J, Wang Y, Spencer DD, Bordey A. Ectopic HCN4 expression drives mTOR-dependent epilepsy in mice. Sci Transl Med 2020; 12:12/570/eabc1492. [PMID: 33208499 PMCID: PMC9888000 DOI: 10.1126/scitranslmed.abc1492] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/31/2020] [Indexed: 02/03/2023]
Abstract
The causative link between focal cortical malformations (FCMs) and epilepsy is well accepted, especially among patients with focal cortical dysplasia type II (FCDII) and tuberous sclerosis complex (TSC). However, the mechanisms underlying seizures remain unclear. Using a mouse model of TSC- and FCDII-associated FCM, we showed that FCM neurons were responsible for seizure activity via their unexpected abnormal expression of the hyperpolarization-activated cyclic nucleotide-gated potassium channel isoform 4 (HCN4), which is normally not present in cortical pyramidal neurons after birth. Increasing intracellular cAMP concentrations, which preferentially affects HCN4 gating relative to the other isoforms, drove repetitive firing of FCM neurons but not control pyramidal neurons. Ectopic HCN4 expression was dependent on the mechanistic target of rapamycin (mTOR), preceded the onset of seizures, and was also found in diseased neurons in tissue resected from patients with TSC and FCDII. Last, blocking HCN4 channel activity in FCM neurons prevented epilepsy in the mouse model. These findings suggest that HCN4 play a main role in seizure and identify a cAMP-dependent seizure mechanism in TSC and FCDII. Furthermore, the unique expression of HCN4 exclusively in FCM neurons suggests that gene therapy targeting HCN4 might be effective in reducing seizures in FCDII or TSC.
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Affiliation(s)
- Lawrence S. Hsieh
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - John H. Wen
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Lena H. Nguyen
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Longbo Zhang
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Stephanie Getz
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Juan Torres-Reveron
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Ying Wang
- Emergency Department, Xiangya Hospital, Central South University, 87 Xiangya Street, Changsha, Hunan 410008, China
| | - Dennis D. Spencer
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Angélique Bordey
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA,Department of Cellular & Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA,To whom correspondence should be addressed: Angélique Bordey, Ph.D., Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, FMB 422, New Haven, CT 06520-8082, Phone: 203-737-2515, Fax: 203-737-2159,
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26
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Gelot AB, Represa A. Progression of Fetal Brain Lesions in Tuberous Sclerosis Complex. Front Neurosci 2020; 14:899. [PMID: 32973442 PMCID: PMC7472962 DOI: 10.3389/fnins.2020.00899] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 07/31/2020] [Indexed: 11/24/2022] Open
Abstract
Tuberous sclerosis (TSC) is a multisystem autosomal dominant genetic disorder due to loss of function of TSC1/TSC2 resulting in increased mTOR (mammalian target of rapamycin) signaling. In the brain, TSC is characterized by the formation of specific lesions that include subependymal and white matter nodules and cortical tubers. Cells that constitute TSC lesions are mainly Giant cells and dysmorphic neurons and astrocytes, but normal cells also populate the tubers. Although considered as a developmental disorder, the histopathological features of brain lesions have been described in only a limited number of fetal cases, providing little information on how these lesions develop. In this report we characterized the development of TSC lesions in 14 fetal brains ranging from 19 gestational weeks (GW) to term and 2 postnatal cases. The study focused on the telencephalon at the level of the caudothalamic notch. Our data indicate that subcortical lesions, forming within and at the vicinity of germinative zones, are the first alterations (already detected in 19GW brains), characterized by the presence of numerous dysmorphic astrocytes and Giant, balloon-like, cells. Our data show that cortical tuber formation is a long process that initiates with the presence of dysmorphic astrocytes (by 19–21GW), progress with the apparition of Giant cells (by 24GW) and mature with the appearance of dysmorphic neurons by the end of gestation (by 36GW). Furthermore, the typical tuberal aspect of cortical lesions is only reached when bundles of neurofilament positive extensions delineate the bottom of the cortical lesion (by 36GW). In addition, our study reveals the presence of Giant cells and dysmorphic neurons immunopositive for interneuron markers such as calbindin and parvalbumin, suggesting that TSC lesions would be mosaic lesions generated from different classes of progenitors.
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Affiliation(s)
- Antoinette Bernabe Gelot
- Aix-Marseille University, INSERM, INMED, Marseille, France.,APHP, Hôpital Trousseau, Université Pierre et Marie Curie, Paris, France
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Feliciano DM. The Neurodevelopmental Pathogenesis of Tuberous Sclerosis Complex (TSC). Front Neuroanat 2020; 14:39. [PMID: 32765227 PMCID: PMC7381175 DOI: 10.3389/fnana.2020.00039] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/10/2020] [Indexed: 12/22/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is a model disorder for understanding brain development because the genes that cause TSC are known, many downstream molecular pathways have been identified, and the resulting perturbations of cellular events are established. TSC, therefore, provides an intellectual framework to understand the molecular and biochemical pathways that orchestrate normal brain development. The TSC1 and TSC2 genes encode Hamartin and Tuberin which form a GTPase activating protein (GAP) complex. Inactivating mutations in TSC genes (TSC1/TSC2) cause sustained Ras homologue enriched in brain (RHEB) activation of the mammalian isoform of the target of rapamycin complex 1 (mTORC1). TOR is a protein kinase that regulates cell size in many organisms throughout nature. mTORC1 inhibits catabolic processes including autophagy and activates anabolic processes including mRNA translation. mTORC1 regulation is achieved through two main upstream mechanisms. The first mechanism is regulation by growth factor signaling. The second mechanism is regulation by amino acids. Gene mutations that cause too much or too little mTORC1 activity lead to a spectrum of neuroanatomical changes ranging from altered brain size (micro and macrocephaly) to cortical malformations to Type I neoplasias. Because somatic mutations often underlie these changes, the timing, and location of mutation results in focal brain malformations. These mutations, therefore, provide gain-of-function and loss-of-function changes that are a powerful tool to assess the events that have gone awry during development and to determine their functional physiological consequences. Knowledge about the TSC-mTORC1 pathway has allowed scientists to predict which upstream and downstream mutations should cause commensurate neuroanatomical changes. Indeed, many of these predictions have now been clinically validated. A description of clinical imaging and histochemical findings is provided in relation to laboratory models of TSC that will allow the reader to appreciate how human pathology can provide an understanding of the fundamental mechanisms of development.
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Affiliation(s)
- David M Feliciano
- Department of Biological Sciences, Clemson University, Clemson, SC, United States
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28
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Villanueva MT. Small molecule reduces epileptic seizures in mice. Nat Rev Drug Discov 2020; 19:238. [PMID: 32161370 DOI: 10.1038/d41573-020-00042-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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