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Le Belle JE, Condro M, Cepeda C, Oikonomou KD, Tessema K, Dudley L, Schoenfield J, Kawaguchi R, Geschwind D, Silva AJ, Zhang Z, Shokat K, Harris NG, Kornblum HI. Acute rapamycin treatment reveals novel mechanisms of behavioral, physiological, and functional dysfunction in a maternal inflammation mouse model of autism and sensory over-responsivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.08.602602. [PMID: 39026891 PMCID: PMC11257517 DOI: 10.1101/2024.07.08.602602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Maternal inflammatory response (MIR) during early gestation in mice induces a cascade of physiological and behavioral changes that have been associated with autism spectrum disorder (ASD). In a prior study and the current one, we find that mild MIR results in chronic systemic and neuro-inflammation, mTOR pathway activation, mild brain overgrowth followed by regionally specific volumetric changes, sensory processing dysregulation, and social and repetitive behavior abnormalities. Prior studies of rapamycin treatment in autism models have focused on chronic treatments that might be expected to alter or prevent physical brain changes. Here, we have focused on the acute effects of rapamycin to uncover novel mechanisms of dysfunction and related to mTOR pathway signaling. We find that within 2 hours, rapamycin treatment could rapidly rescue neuronal hyper-excitability, seizure susceptibility, functional network connectivity and brain community structure, and repetitive behaviors and sensory over-responsivity in adult offspring with persistent brain overgrowth. These CNS-mediated effects are also associated with alteration of the expression of several ASD-,ion channel-, and epilepsy-associated genes, in the same time frame. Our findings suggest that mTOR dysregulation in MIR offspring is a key contributor to various levels of brain dysfunction, including neuronal excitability, altered gene expression in multiple cell types, sensory functional network connectivity, and modulation of information flow. However, we demonstrate that the adult MIR brain is also amenable to rapid normalization of these functional changes which results in the rescue of both core and comorbid ASD behaviors in adult animals without requiring long-term physical alterations to the brain. Thus, restoring excitatory/inhibitory imbalance and sensory functional network modularity may be important targets for therapeutically addressing both primary sensory and social behavior phenotypes, and compensatory repetitive behavior phenotypes.
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Hu JS, Malik R, Sohal VS, Rubenstein JL, Vogt D. Tsc1 Loss in VIP-Lineage Cortical Interneurons Results in More VIP+ Interneurons and Enhanced Excitability. Cells 2023; 13:52. [PMID: 38201256 PMCID: PMC10777938 DOI: 10.3390/cells13010052] [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: 09/01/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
The mammalian target of rapamycin (mTOR) signaling pathway is a powerful regulator of cell proliferation, growth, synapse maintenance and cell fate. While intensely studied for its role in cancer, the role of mTOR signaling is just beginning to be uncovered in specific cell types that are implicated in neurodevelopmental disorders. Previously, loss of the Tsc1 gene, which results in hyperactive mTOR, was shown to affect the function and molecular properties of GABAergic cortical interneurons (CINs) derived from the medial ganglionic eminence. To assess if other important classes of CINs could be impacted by mTOR dysfunction, we deleted Tsc1 in a caudal ganglionic eminence-derived interneuron group, the vasoactive intestinal peptide (VIP)+ subtype, whose activity disinhibits local circuits. Tsc1 mutant VIP+ CINs reduced their pattern of apoptosis from postnatal days 15-20, resulting in increased VIP+ CINs. The mutant CINs exhibited synaptic and electrophysiological properties that could contribute to the high rate of seizure activity in humans that harbor Tsc1 mutations.
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Affiliation(s)
- Jia Sheng Hu
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ruchi Malik
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
- Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA 94158, USA
- Center for Integrative Neuroscience, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
| | - Vikaas S. Sohal
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
- Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA 94158, USA
- Center for Integrative Neuroscience, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
| | - John L. Rubenstein
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Daniel Vogt
- Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, MI 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
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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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Chaudry S, Vasudevan N. mTOR-Dependent Spine Dynamics in Autism. Front Mol Neurosci 2022; 15:877609. [PMID: 35782388 PMCID: PMC9241970 DOI: 10.3389/fnmol.2022.877609] [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: 02/16/2022] [Accepted: 04/25/2022] [Indexed: 12/12/2022] Open
Abstract
Autism Spectrum Conditions (ASC) are a group of neurodevelopmental disorders characterized by deficits in social communication and interaction as well as repetitive behaviors and restricted range of interests. ASC are complex genetic disorders with moderate to high heritability, and associated with atypical patterns of neural connectivity. Many of the genes implicated in ASC are involved in dendritic spine pruning and spine development, both of which can be mediated by the mammalian target of rapamycin (mTOR) signaling pathway. Consistent with this idea, human postmortem studies have shown increased spine density in ASC compared to controls suggesting that the balance between autophagy and spinogenesis is altered in ASC. However, murine models of ASC have shown inconsistent results for spine morphology, which may underlie functional connectivity. This review seeks to establish the relevance of changes in dendritic spines in ASC using data gathered from rodent models. Using a literature survey, we identify 20 genes that are linked to dendritic spine pruning or development in rodents that are also strongly implicated in ASC in humans. Furthermore, we show that all 20 genes are linked to the mTOR pathway and propose that the mTOR pathway regulating spine dynamics is a potential mechanism underlying the ASC signaling pathway in ASC. We show here that the direction of change in spine density was mostly correlated to the upstream positive or negative regulation of the mTOR pathway and most rodent models of mutant mTOR regulators show increases in immature spines, based on morphological analyses. We further explore the idea that these mutations in these genes result in aberrant social behavior in rodent models that is due to these altered spine dynamics. This review should therefore pave the way for further research on the specific genes outlined, their effect on spine morphology or density with an emphasis on understanding the functional role of these changes in ASC.
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Niescier RF, Lin YC. The Potential Role of AMPA Receptor Trafficking in Autism and Other Neurodevelopmental Conditions. Neuroscience 2021; 479:180-191. [PMID: 34571086 DOI: 10.1016/j.neuroscience.2021.09.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 09/06/2021] [Accepted: 09/15/2021] [Indexed: 12/21/2022]
Abstract
Autism Spectrum Disorder (ASD) is a multifaceted condition associated with difficulties in social interaction and communication. It also shares several comorbidities with other neurodevelopmental conditions. Intensive research examining the molecular basis and characteristics of ASD has revealed an association with a large number and variety of low-penetrance genes. Many of the variants associated with ASD are in genes underlying pathways involved in long-term potentiation (LTP) or depression (LTD). These mechanisms then control the tuning of neuronal connections in response to experience by modifying and trafficking ionotropic glutamate receptors at the post-synaptic areas. Despite the high genetic heterogeneity in ASD, surface trafficking of the α-amino-3-hydroxy-5-Methyl-4-isoxazolepropionate (AMPA) receptor is a vulnerable pathway in ASD. In this review, we discuss autism-related alterations in the trafficking of AMPA receptors, whose surface density and composition at the post-synapse determine the strength of the excitatory connection between neurons. We highlight genes associated with neurodevelopmental conditions that share the autism comorbidity, including Fragile X syndrome, Rett Syndrome, and Tuberous Sclerosis, as well as the autism-risk genes NLGNs, IQSEC2, DOCK4, and STXBP5, all of which are involved in regulating AMPAR trafficking to the post-synaptic surface.
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Affiliation(s)
- Robert F Niescier
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA.
| | - Yu-Chih Lin
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA.
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Moschopoulos C, Peters JM, Takeoka M, Stredny CM. Infantile Hemiconvulsion-Hemiplegia and Epilepsy (IHHE) in a boy with tuberous sclerosis complex. Epilepsy Behav Rep 2021; 16:100473. [PMID: 34466799 PMCID: PMC8383053 DOI: 10.1016/j.ebr.2021.100473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/25/2021] [Accepted: 08/02/2021] [Indexed: 11/23/2022] Open
Abstract
Case of IHHE with hemiclonic status epilepticus in a patient with TSC2. MRI revealed unihemispheric edema and restricted diffusion evolving to atrophy. Brain malformations and genetic predisposition may contribute to acquiring IHHE.
Tuberous sclerosis complex (TSC) is a rare autosomal dominant disease due to pathogenic variants in TSC1 or TSC2 genes. In the brain, TSC is associated with multiple cortical and subcortical malformations including tubers and abnormalities of radial neuronal migration. Approximately 80% of patients develop epilepsy in the first two years of life, most often focal seizures and infantile spasms. As with all seizure disorders, systemic illness and fever can trigger a seizure, and result in status epilepticus or even refractory status epilepticus. Infantile Hemiconvulsion-Hemiplegia and Epilepsy (IHHE) is considered a subcategory of new-onset refractory status epilepticus (NORSE) and presents with hemiclonic seizures in the setting of fever, unihemispheric brain imaging abnormality and hemiparesis. Here, we present an 18-month-old boy with TSC who developed IHHE. His extensive brain malformations and neuronal hyperexcitability in peri-tuberal tissue could have predisposed him to IHHE. In addition to these factors, we postulate that another prerequisite for IHHE is likely a genetic predisposition for an excessive inflammatory response that is yet to be elucidated.
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Affiliation(s)
| | | | | | - Coral M. Stredny
- Corresponding author at: Department of Neurology, Division of Epilepsy and Clinical Neurophysiology, Boston Children’s Hospital, 300 Longwood Ave, Fegan 11, Boston, MA 02115, USA.
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Liu DC, Lee KY, Lizarazo S, Cook JK, Tsai NP. ER stress-induced modulation of neural activity and seizure susceptibility is impaired in a fragile X syndrome mouse model. Neurobiol Dis 2021; 158:105450. [PMID: 34303799 DOI: 10.1016/j.nbd.2021.105450] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 07/18/2021] [Indexed: 01/29/2023] Open
Abstract
Imbalanced neuronal excitability homeostasis is commonly observed in patients with fragile X syndrome (FXS) and the animal model of FXS, the Fmr1 KO. While alterations of neuronal intrinsic excitability and synaptic activity at the steady state in FXS have been suggested to contribute to such a deficit and ultimately the increased susceptibility to seizures in FXS, it remains largely unclear whether and how the homeostatic response of neuronal excitability following extrinsic challenges is disrupted in FXS. Our previous work has shown that the acute response following induction of endoplasmic reticulum (ER) stress can reduce neural activity and seizure susceptibility. Because many signaling pathways associated with ER stress response are mediated by Fmr1, we asked whether acute ER stress-induced reduction of neural activity and seizure susceptibility are altered in FXS. Our results first revealed that acute ER stress can trigger a protein synthesis-dependent prevention of neural network synchronization in vitro and a reduction of susceptibility to kainic acid-induced seizures in vivo in wild-type but not in Fmr1 KO mice. Mechanistically, we found that acute ER stress-induced activation of murine double minute-2 (Mdm2), ubiquitination of p53, and the subsequent transient protein synthesis are all impaired in Fmr1 KO neurons. Employing a p53 inhibitor, Pifithrin-α, to mimic p53 inactivation, we were able to blunt the increase in neural network synchronization and reduce the seizure susceptibility in Fmr1 KO mice following ER stress induction. In summary, our data revealed a novel cellular defect in Fmr1 KO mice and suggest that an impaired response to common extrinsic challenges may contribute to imbalanced neuronal excitability homeostasis in FXS.
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Affiliation(s)
- Dai-Chi Liu
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Kwan Young Lee
- Department of Molecular and Integrative Physiology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Simon Lizarazo
- Department of Molecular and Integrative Physiology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jessie K Cook
- Department of Molecular and Integrative Physiology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Nien-Pei Tsai
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Molecular and Integrative Physiology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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Bassetti D, Luhmann HJ, Kirischuk S. Presynaptic GABA B receptor-mediated network excitation in the medial prefrontal cortex of Tsc2 +/- mice. Pflugers Arch 2021; 473:1261-1271. [PMID: 34279736 PMCID: PMC8302497 DOI: 10.1007/s00424-021-02576-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/21/2021] [Accepted: 05/05/2021] [Indexed: 11/02/2022]
Abstract
The TSC1 and TSC2 tumor suppressor genes control the activity of mechanistic target of rapamycin (mTOR) pathway. Elevated activity of this pathway in Tsc2+/- mouse model leads to reduction of postsynaptic GABAB receptor-mediated inhibition and hyperexcitability in the medial prefrontal cortex (mPFC). In this study, we asked whether presynaptic GABAB receptors (GABABRs) can compensate this shift of hyperexcitability. Experiments were performed in brain slices from adolescent wild-type (WT) and Tsc2+/- mice. Miniature and spontaneous postsynaptic currents (m/sPSCs) were recorded from layer 2/3 pyramidal neurons in mPFC using patch-clamp technique using a Cs+-based intrapipette solution. Presynaptic GABABRs were activated by baclofen (10 µM) or blocked by CGP55845 (1 µM). Independent on genotype, GABABR modulators bidirectionally change miniature excitatory postsynaptic current (mEPSC) frequency by about 10%, indicating presynaptic GABABR-mediated effects on glutamatergic transmission are comparable in both genotypes. In contrast, frequencies of both mIPSCs and sIPCSs were suppressed by baclofen stronger in Tsc2+/- neurons than in WT ones, whereas CGP55845 significantly increased (m/s)IPSC frequencies only in WT cells. Effects of baclofen and CGP55845 on the amplitudes of evoked (e)IPSCs confirmed these observations. These data indicate (1) that GABAergic synapses are inhibited by ambient GABA in WT but not in Tsc2+/- slices, and (2) that baclofen shifts the E/I ratio, determined as the ratio of (m/s)EPSC frequency to (m/s)IPSC frequency, towards excitation only in Tsc2+/- cells. This excitatory presynaptic GABABR-mediated action has to be taken into account for a possible medication of mental disorders using baclofen.
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Affiliation(s)
- Davide Bassetti
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128, Mainz, Germany.
| | - Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128, Mainz, Germany
| | - Sergei Kirischuk
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128, Mainz, Germany
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Bassetti D, Luhmann HJ, Kirischuk S. Effects of Mutations in TSC Genes on Neurodevelopment and Synaptic Transmission. Int J Mol Sci 2021; 22:7273. [PMID: 34298906 PMCID: PMC8305053 DOI: 10.3390/ijms22147273] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in TSC1 or TSC2 genes are linked to alterations in neuronal function which ultimately lead to the development of a complex neurological phenotype. Here we review current research on the effects that reduction in TSC1 or TSC2 can produce on the developing neural network. A crucial feature of the disease pathophysiology appears to be an early deviation from typical neurodevelopment, in the form of structural abnormalities. Epileptic seizures are one of the primary early manifestation of the disease in the CNS, followed by intellectual deficits and autism spectrum disorders (ASD). Research using mouse models suggests that morphological brain alterations might arise from the interaction of different cellular types, and hyperexcitability in the early postnatal period might be transient. Moreover, the increased excitation-to-inhibition ratio might represent a transient compensatory adjustment to stabilize the developing network rather than a primary factor for the development of ASD symptoms. The inhomogeneous results suggest region-specificity as well as an evolving picture of functional alterations along development. Furthermore, ASD symptoms and epilepsy might originate from different but potentially overlapping mechanisms, which can explain recent observations obtained in patients. Potential treatment is determined not only by the type of medicament, but also by the time point of treatment.
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Affiliation(s)
- Davide Bassetti
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, 55128 Mainz, Germany; (H.J.L.); (S.K.)
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Mizuguchi M, Ohsawa M, Kashii H, Sato A. Brain Symptoms of Tuberous Sclerosis Complex: Pathogenesis and Treatment. Int J Mol Sci 2021; 22:ijms22136677. [PMID: 34206526 PMCID: PMC8268912 DOI: 10.3390/ijms22136677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/16/2021] [Accepted: 06/19/2021] [Indexed: 12/12/2022] Open
Abstract
The mammalian target of the rapamycin (mTOR) system plays multiple, important roles in the brain, regulating both morphology, such as cellular size, shape, and position, and function, such as learning, memory, and social interaction. Tuberous sclerosis complex (TSC) is a congenital disorder caused by a defective suppressor of the mTOR system, the TSC1/TSC2 complex. Almost all brain symptoms of TSC are manifestations of an excessive activity of the mTOR system. Many children with TSC are afflicted by intractable epilepsy, intellectual disability, and/or autism. In the brains of infants with TSC, a vicious cycle of epileptic encephalopathy is formed by mTOR hyperactivity, abnormal synaptic structure/function, and excessive epileptic discharges, further worsening epilepsy and intellectual/behavioral disorders. Molecular target therapy with mTOR inhibitors has recently been proved to be efficacious for epilepsy in human TSC patients, and for autism in TSC model mice, indicating the possibility for pharmacological treatment of developmental synaptic disorders.
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Affiliation(s)
- Masashi Mizuguchi
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
- Department of Pediatrics, National Rehabilitation Center for Children with Disabilities, Itabashi-ku, Tokyo 173-0037, Japan
- Correspondence: ; Tel.: +81-3-5841-3515
| | - Maki Ohsawa
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
- Department of Pediatrics, National Rehabilitation Center for Children with Disabilities, Itabashi-ku, Tokyo 173-0037, Japan
| | - Hirofumi Kashii
- Department of Neuropediatrics, Tokyo Metropolitan Neurological Hospital, Fuchu, Tokyo 183-0042, Japan;
| | - Atsushi Sato
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan;
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Sensitive period for rescuing parvalbumin interneurons connectivity and social behavior deficits caused by TSC1 loss. Nat Commun 2021; 12:3653. [PMID: 34135323 PMCID: PMC8209106 DOI: 10.1038/s41467-021-23939-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 05/20/2021] [Indexed: 11/08/2022] Open
Abstract
The Mechanistic Target Of Rapamycin Complex 1 (mTORC1) pathway controls several aspects of neuronal development. Mutations in regulators of mTORC1, such as Tsc1 and Tsc2, lead to neurodevelopmental disorders associated with autism, intellectual disabilities and epilepsy. The correct development of inhibitory interneurons is crucial for functional circuits. In particular, the axonal arborisation and synapse density of parvalbumin (PV)-positive GABAergic interneurons change in the postnatal brain. How and whether mTORC1 signaling affects PV cell development is unknown. Here, we show that Tsc1 haploinsufficiency causes a premature increase in terminal axonal branching and bouton density formed by mutant PV cells, followed by a loss of perisomatic innervation in adult mice. PV cell-restricted Tsc1 haploinsufficient and knockout mice show deficits in social behavior. Finally, we identify a sensitive period during the third postnatal week during which treatment with the mTOR inhibitor Rapamycin rescues deficits in both PV cell innervation and social behavior in adult conditional haploinsufficient mice. Our findings reveal a role of mTORC1 signaling in the regulation of the developmental time course and maintenance of cortical PV cell connectivity and support a mechanistic basis for the targeted rescue of autism-related behaviors in disorders associated with deregulated mTORC1 signaling.
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Neuron-Glia Interactions in Tuberous Sclerosis Complex Affect the Synaptic Balance in 2D and Organoid Cultures. Cells 2021; 10:cells10010134. [PMID: 33445520 PMCID: PMC7826837 DOI: 10.3390/cells10010134] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 02/06/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a genetic disease affecting the brain. Neurological symptoms like epilepsy and neurodevelopmental issues cause a significant burden on patients. Both neurons and glial cells are affected by TSC mutations. Previous studies have shown changes in the excitation/inhibition balance (E/I balance) in TSC. Astrocytes are known to be important for neuronal development, and astrocytic dysfunction can cause changes in the E/I balance. We hypothesized that astrocytes affect the synaptic balance in TSC. TSC patient-derived stem cells were differentiated into astrocytes, which showed increased proliferation compared to control astrocytes. RNA sequencing revealed changes in gene expression, which were related to epidermal growth factor (EGF) signaling and enriched for genes that coded for secreted or transmembrane proteins. Control neurons were cultured in astrocyte-conditioned medium (ACM) of TSC and control astrocytes. After culture in TSC ACM, neurons showed an altered synaptic balance, with an increase in the percentage of VGAT+ synapses. These findings were confirmed in organoids, presenting a spontaneous 3D organization of neurons and glial cells. To conclude, this study shows that TSC astrocytes are affected and secrete factors that alter the synaptic balance. As an altered E/I balance may underlie many of the neurological TSC symptoms, astrocytes may provide new therapeutic targets.
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Kanemura H, Sano F, Hoshino H, Aihara M. Efficacy of perampanel in epilepsy patients with autism spectrum disorder. Epilepsy Res 2021; 170:106550. [PMID: 33450524 DOI: 10.1016/j.eplepsyres.2021.106550] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/13/2020] [Accepted: 12/30/2020] [Indexed: 11/30/2022]
Abstract
AIM The aim of this study was to assess the usefulness of perampanel (PER), and to identify the relationship between behavioral impairments and electroencephalogram (EEG) findings in epilepsy patients with autism spectrum disorder (ASD). METHODS Participants were ASD patients with epilepsy recruited between June 1, 2016 and June 30, 2018. Inclusion criteria were: seizures refractory to two appropriate antiseizure medications (ASMs); presence of neuropsychological impairments; and ≥12 months of monitoring. PER was administered once daily, starting at a dose of 2 mg/day, increased to 12 mg/day. Seizure/EEG responders were identified as participants showing a >50 % reduction in seizure/interictal epileptiform discharge (IED) frequency (indicated as complete disappearance and response). Behavioral responders were identified as participants with a ≥50 % reduction in scores of the Japanese manuals for the Aberrant Behavior Checklist (ABC-J). RESULTS Eleven (64.7 %) of 17 patients were considered to be both seizure and EEG responders. Five (45.5 %) of these 11 patients with seizure/EEG response were considered as behavioral responders. Mean ABC-J scores were significantly decreased at 12 months after PER administration (p = 0.0002). A correlation between decreased IED frequency and ABC-J score was evident in frontal IEDs, but not in non-frontal IEDs. Participants presenting with frontal IEDs showed a significantly higher correlation between seizures/EEG and behavioral improvements (p = 0.023). Moreover, 2 of 6 patients without seizure/EEG improvement were considered as behavioral responders. No patients discontinued PER. CONCLUSIONS The results from this study suggest the utility of PER treatment in reducing clinical seizures and IEDs for ASD patients with intractable epilepsy, at least in some patients. Moreover, the present results also indicate the usefulness of PER in improving neuropsychiatric impairments, including behavioral disturbances in ASD related to improvement of clinical seizures/frontal IEDs, but also unrelated to seizure/EEG improvement in at least some ASD patients.
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Affiliation(s)
- Hideaki Kanemura
- Department of Pediatrics, Toho University Medical Center Sakura Hospital, 564-1 Shimoshizu, Sakura, Chiba, 285-8741, Japan; Department of Pediatrics, Faculty of Medicine, University of Yamanashi, 1110 Chuo, Yamanashi, 409-3898, Japan.
| | - Fumikazu Sano
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, 1110 Chuo, Yamanashi, 409-3898, Japan.
| | - Hiroki Hoshino
- Department of Pediatrics, Toho University Medical Center Sakura Hospital, 564-1 Shimoshizu, Sakura, Chiba, 285-8741, Japan.
| | - Masao Aihara
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Chuo, Yamanashi, 409-3898, Japan.
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14
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Alsaqati M, Heine VM, Harwood AJ. Pharmacological intervention to restore connectivity deficits of neuronal networks derived from ASD patient iPSC with a TSC2 mutation. Mol Autism 2020; 11:80. [PMID: 33076974 PMCID: PMC7574213 DOI: 10.1186/s13229-020-00391-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/08/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Tuberous sclerosis complex (TSC) is a rare genetic multisystemic disorder resulting from autosomal dominant mutations in the TSC1 or TSC2 genes. It is characterised by hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway and has severe neurodevelopmental and neurological components including autism, intellectual disability and epilepsy. In human and rodent models, loss of the TSC proteins causes neuronal hyperexcitability and synaptic dysfunction, although the consequences of these changes for the developing central nervous system are currently unclear. METHODS Here we apply multi-electrode array-based assays to study the effects of TSC2 loss on neuronal network activity using autism spectrum disorder (ASD) patient-derived iPSCs. We examine both temporal synchronisation of neuronal bursting and spatial connectivity between electrodes across the network. RESULTS We find that ASD patient-derived neurons with a functional loss of TSC2, in addition to possessing neuronal hyperactivity, develop a dysfunctional neuronal network with reduced synchronisation of neuronal bursting and lower spatial connectivity. These deficits of network function are associated with elevated expression of genes for inhibitory GABA signalling and glutamate signalling, indicating a potential abnormality of synaptic inhibitory-excitatory signalling. mTORC1 activity functions within a homeostatic triad of protein kinases, mTOR, AMP-dependent protein Kinase 1 (AMPK) and Unc-51 like Autophagy Activating Kinase 1 (ULK1) that orchestrate the interplay of anabolic cell growth and catabolic autophagy while balancing energy and nutrient homeostasis. The mTOR inhibitor rapamycin suppresses neuronal hyperactivity, but does not increase synchronised network activity, whereas activation of AMPK restores some aspects of network activity. In contrast, the ULK1 activator, LYN-1604, increases the network behaviour, shortens the network burst lengths and reduces the number of uncorrelated spikes. LIMITATIONS Although a robust and consistent phenotype is observed across multiple independent iPSC cultures, the results are based on one patient. There may be more subtle differences between patients with different TSC2 mutations or differences of polygenic background within their genomes. This may affect the severity of the network deficit or the pharmacological response between TSC2 patients. CONCLUSIONS Our observations suggest that there is a reduction in the network connectivity of the in vitro neuronal network associated with ASD patients with TSC2 mutation, which may arise via an excitatory/inhibitory imbalance due to increased GABA-signalling at inhibitory synapses. This abnormality can be effectively suppressed via activation of ULK1.
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Affiliation(s)
- Mouhamed Alsaqati
- Neuroscience and Mental Health Research Institute, Hadyn Ellis Building, Cathays, Cardiff, CF24 4HQ, UK
- Division of Psychological Medicine and Clinical Neurosciences (DPMCN), School of Medicine, Cardiff University, Cardiff, UK
| | - Vivi M Heine
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Child and Youth Psychiatry, Emma Children's Hospital, Amsterdam UMC, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Adrian J Harwood
- Neuroscience and Mental Health Research Institute, Hadyn Ellis Building, Cathays, Cardiff, CF24 4HQ, UK.
- School of Bioscience, The Sir Martin Evans Building, Museum Ave, Cardiff, CF10 3AX, UK.
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15
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GABAergic Interneuron and Neurotransmission Are mTOR-Dependently Disturbed in Experimental Focal Cortical Dysplasia. Mol Neurobiol 2020; 58:156-169. [PMID: 32909150 DOI: 10.1007/s12035-020-02086-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 08/21/2020] [Indexed: 01/13/2023]
Abstract
Focal cortical dysplasia (FCD) is a major cause for drug-resistant epilepsies. The molecular and cellular mechanisms of epileptogenesis in FCD are still poorly understood. Some studies have suggested that deficiencies of γ-aminobutyric acid (GABA) system may play an important role in type II FCD, but it remains controversial. In order to examine whether and how GABAergic interneurons and synaptic function are affected, we generated a somatic mTOR hyperactivation-based mouse model of type II FCD by in utero electroporation, quantified densities of interneurons in the malformed cortices, and recorded miniature inhibitory postsynaptic currents in dysmorphic neurons. We detected 20-25% reduction of GABAergic interneurons within malformed cortices, independent of cortical regions and cell subtypes but proportionate to the decrease of global neuron counts. GABAergic synaptic transmission from interneurons to mTOR hyperactivated dysmorphic neurons was dramatically disrupted, outweighing the decrease of interneuron counts. Postnatal mTOR inhibition partially rescued these alterations of GABAergic system. We also quantified the expression of GABAA receptor, GABA transporter, and chloridion transporter encoding genes and found that their expression was relatively intact within the malformed cortices. Taken together, these results confirmed that GABAergic interneuron and synapse transmission are disturbed profoundly in an mTOR-dependent manner in type II FCD. Our study suggests that postsynaptic mechanisms independent of interneuron reduction or altered expression of GABA synapse genes might be accountable for the impaired GABAergic neurotransmission in type II FCD as well as other mTOR-related epilepsies.
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16
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Bassetti D, Lombardi A, Kirischuk S, Luhmann HJ. Haploinsufficiency of Tsc2 Leads to Hyperexcitability of Medial Prefrontal Cortex via Weakening of Tonic GABAB Receptor-mediated Inhibition. Cereb Cortex 2020; 30:6313-6324. [PMID: 32705128 DOI: 10.1093/cercor/bhaa187] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/16/2020] [Accepted: 06/16/2020] [Indexed: 12/30/2022] Open
Abstract
Loss-of-function mutation in one of the tumor suppressor genes TSC1 or TSC2 is associated with several neurological and psychiatric diseases, including autism spectrum disorders (ASDs). As an imbalance between excitatory and inhibitory neurotransmission, E/I ratio is believed to contribute to the development of these disorders, we investigated synaptic transmission during the first postnatal month using the Tsc2+/- mouse model. Electrophysiological recordings were performed in acute brain slices of medial prefrontal cortex. E/I ratio at postnatal day (P) 15-19 is increased in Tsc2+/- mice as compared with wildtype (WT). At P25-30, facilitated GABAergic transmission reduces E/I ratio to the WT level, but weakening of tonic GABAB receptor (GABABR)-mediated inhibition in Tsc2+/- mice leads to hyperexcitability both at single cell and neuronal network level. Short (1 h) preincubation of P25-30 Tsc2+/- slices with baclofen restores the GABABR-mediated inhibition and reduces network excitability. Interestingly, the same treatment at P15-19 leads to weakening of GABABR-mediated inhibition. We hypothesize that a dysfunction of tonic GABABR-mediated inhibition might contribute to the development of ASD symptoms and suggest that GABABR activation within an appropriate time window may be considered as a therapeutic target in ASD.
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Affiliation(s)
- Davide Bassetti
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz D-55128, Germany
| | - Aniello Lombardi
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz D-55128, Germany
| | - Sergei Kirischuk
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz D-55128, Germany
| | - Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz D-55128, Germany
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17
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Haji N, Riebe I, Aguilar-Valles A, Artinian J, Laplante I, Lacaille JC. Tsc1 haploinsufficiency in Nkx2.1 cells upregulates hippocampal interneuron mTORC1 activity, impairs pyramidal cell synaptic inhibition, and alters contextual fear discrimination and spatial working memory in mice. Mol Autism 2020; 11:29. [PMID: 32375878 PMCID: PMC7201610 DOI: 10.1186/s13229-020-00340-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/24/2020] [Indexed: 12/23/2022] Open
Abstract
Background Mutations in TSC1 or TSC2 genes cause tuberous sclerosis complex (TSC), a disorder associated with epilepsy, autism, and intellectual disability. TSC1 and TSC2 are repressors of the mechanistic target of rapamycin complex 1 (mTORC1), a key regulator of protein synthesis. Dysregulation of mTORC1 in TSC mouse models leads to impairments in excitation-inhibition balance, synaptic plasticity, and hippocampus-dependent learning and memory deficits. However, synaptic inhibition arises from multiple types of inhibitory interneurons and how changes in specific interneurons contribute to TSC remains largely unknown. In the present work, we determined the effect of conditional Tsc1 haploinsufficiency in a specific subgroup of inhibitory cells on hippocampal function in mice. Methods We investigated the consequences of conditional heterozygous knockout of Tsc1 in MGE-derived inhibitory cells by crossing Nkx2.1Cre/wt;Tsc1f/f mice. We examined the changes in mTORC1 activity and synaptic transmission in hippocampal cells, as well as hippocampus-related cognitive tasks. Results We detected selective increases in phosphorylation of ribosomal protein S6 in interneurons, indicating cell-specific-upregulated mTORC1 signaling. At the behavioral level, Nkx2.1Cre/wt;Tsc1f/wt mice exhibited intact contextual fear memory, but impaired contextual fear discrimination. They displayed intact spatial learning and reference memory but impairment in spatial working memory. Whole-cell recordings in hippocampal slices of Nkx2.1Cre/wt;Tsc1f/wt mice showed intact basic membrane properties, as well as miniature excitatory and inhibitory synaptic transmission, in pyramidal and Nkx2.1-expressing inhibitory cells. Using optogenetic activation of Nkx2.1 interneurons in slices of Nkx2.1Cre/wt;Tsc1f/wt mice, we found a decrease in synaptic inhibition of pyramidal cells. Chronic, but not acute treatment, with the mTORC1 inhibitor rapamycin reversed the impairment in synaptic inhibition. Conclusions Our results indicate that Tsc1 haploinsufficiency in MGE-derived inhibitory cells upregulates mTORC1 activity in these interneurons, reduces their synaptic inhibition of pyramidal cells, and alters contextual fear discrimination and spatial working memory. Thus, selective dysregulation of mTORC1 function in Nkx2.1-expressing inhibitory cells appears sufficient to impair synaptic inhibition and contributes to cognitive deficits in the Tsc1 mouse model of TSC.
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Affiliation(s)
- Nabila Haji
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Ilse Riebe
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Argel Aguilar-Valles
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada.,Department of Biochemistry and Goodman Cancer Centre, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada
| | - Julien Artinian
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Isabel Laplante
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Quebec, H3C 3 J7, Canada.
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18
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Visualization of AMPA receptors in living human brain with positron emission tomography. Nat Med 2020; 26:281-288. [PMID: 31959988 DOI: 10.1038/s41591-019-0723-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 11/27/2019] [Indexed: 12/14/2022]
Abstract
Although aberrations in the number and function of glutamate AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors are thought to underlie neuropsychiatric disorders, no methods are currently available for visualizing AMPA receptors in the living human brain. Here we developed a positron emission tomography (PET) tracer for AMPA receptors. A derivative of 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetamide radiolabeled with 11C ([11C]K-2) showed specific binding to AMPA receptors. Our clinical trial with healthy human participants confirmed reversible binding of [11C]K-2 in the brain according to Logan graphical analysis (UMIN000020975; study design: non-randomized, single arm; primary outcome: dynamics and distribution volumes of [11C]K-2 in the brain; secondary outcome: adverse events of [11C]K-2 during the 4-10 d following dosing; this trial met prespecified endpoints). In an exploratory clinical study including patients with epilepsy, we detected increased [11C]K-2 uptake in the epileptogenic focus of patients with mesial temporal lobe epilepsy, which was closely correlated with the local AMPA receptor protein distribution in surgical specimens from the same individuals (UMIN000025090; study design: non-randomized, single arm; primary outcome: correlation between [11C]K-2 uptake measured with PET before surgery and AMPA receptor protein density examined by biochemical study after surgery; secondary outcome: adverse events during the 7 d following PET scan; this trial met prespecified endpoints). Thus, [11C]K-2 is a potent PET tracer for AMPA receptors, potentially providing a tool to examine the involvement of AMPA receptors in neuropsychiatric disorders.
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19
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Malik R, Pai ELL, Rubin AN, Stafford AM, Angara K, Minasi P, Rubenstein JL, Sohal VS, Vogt D. Tsc1 represses parvalbumin expression and fast-spiking properties in somatostatin lineage cortical interneurons. Nat Commun 2019; 10:4994. [PMID: 31676823 PMCID: PMC6825152 DOI: 10.1038/s41467-019-12962-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 10/04/2019] [Indexed: 12/21/2022] Open
Abstract
Medial ganglionic eminence (MGE)-derived somatostatin (SST)+ and parvalbumin (PV)+ cortical interneurons (CINs), have characteristic molecular, anatomical and physiological properties. However, mechanisms regulating their diversity remain poorly understood. Here, we show that conditional loss of the Tuberous Sclerosis Complex (TSC) gene, Tsc1, which inhibits the mammalian target of rapamycin (MTOR), causes a subset of SST+ CINs, to express PV and adopt fast-spiking (FS) properties, characteristic of PV+ CINs. Milder intermediate phenotypes also occur when only one allele of Tsc1 is deleted. Notably, treatment of adult mice with rapamycin, which inhibits MTOR, reverses the phenotypes. These data reveal novel functions of MTOR signaling in regulating PV expression and FS properties, which may contribute to TSC neuropsychiatric symptoms. Moreover, they suggest that CINs can exhibit properties intermediate between those classically associated with PV+ or SST+ CINs, which may be dynamically regulated by the MTOR signaling.
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Affiliation(s)
- Ruchi Malik
- Department of Psychiatry and UCSF Weill Institute for Neurosciences, 675 Nelson Rising Ln, San Francisco, CA, 94158, USA
- Center for Integrative Neuroscience, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
| | - Emily Ling-Lin Pai
- Department of Psychiatry and UCSF Weill Institute for Neurosciences, 675 Nelson Rising Ln, San Francisco, CA, 94158, USA
- Neuroscience Program, UCSF, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
- Nina Ireland Laboratory of Developmental Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
| | - Anna N Rubin
- Department of Psychiatry and UCSF Weill Institute for Neurosciences, 675 Nelson Rising Ln, San Francisco, CA, 94158, USA
- Nina Ireland Laboratory of Developmental Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
| | - April M Stafford
- Department of Pediatrics and Human Development, 400 Monroe Ave. NW, Grand Rapids, MI, 49503, USA
| | - Kartik Angara
- Department of Pediatrics and Human Development, 400 Monroe Ave. NW, Grand Rapids, MI, 49503, USA
| | - Petros Minasi
- Department of Psychiatry and UCSF Weill Institute for Neurosciences, 675 Nelson Rising Ln, San Francisco, CA, 94158, USA
| | - John L Rubenstein
- Department of Psychiatry and UCSF Weill Institute for Neurosciences, 675 Nelson Rising Ln, San Francisco, CA, 94158, USA
- Neuroscience Program, UCSF, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
- Nina Ireland Laboratory of Developmental Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA
| | - Vikaas S Sohal
- Department of Psychiatry and UCSF Weill Institute for Neurosciences, 675 Nelson Rising Ln, San Francisco, CA, 94158, USA.
- Center for Integrative Neuroscience, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA.
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA, 94158, USA.
| | - Daniel Vogt
- Department of Pediatrics and Human Development, 400 Monroe Ave. NW, Grand Rapids, MI, 49503, USA.
- Neuroscience Program, Michigan State University, East Lansing, MI, USA.
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