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Volianskis R, Lundbye CJ, Petroff GN, Jane DE, Georgiou J, Collingridge GL. Cage effects on synaptic plasticity and its modulation in a mouse model of fragile X syndrome. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230484. [PMID: 38853552 PMCID: PMC11343313 DOI: 10.1098/rstb.2023.0484] [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: 02/01/2024] [Revised: 04/04/2024] [Accepted: 04/08/2024] [Indexed: 06/11/2024] Open
Abstract
Fragile X syndrome (FXS) is characterized by impairments in executive function including different types of learning and memory. Long-term potentiation (LTP), thought to underlie the formation of memories, has been studied in the Fmr1 mouse model of FXS. However, there have been many discrepancies in the literature with inconsistent use of littermate and non-littermate Fmr1 knockout (KO) and wild-type (WT) control mice. Here, the influence of the breeding strategy (cage effect) on short-term potentiation (STP), LTP, contextual fear conditioning (CFC), expression of N-methyl-d-aspartate receptor (NMDAR) subunits and the modulation of NMDARs, were examined. The largest deficits in STP, LTP and CFC were found in KO mice compared with non-littermate WT. However, the expression of NMDAR subunits was unchanged in this comparison. Rather, NMDAR subunit (GluN1, 2A, 2B) expression was sensitive to the cage effect, with decreased expression in both WT and KO littermates compared with non-littermates. Interestingly, an NMDAR-positive allosteric modulator, UBP714, was only effective in potentiating the induction of LTP in non-littermate KO mice and not the littermate KO mice. These results suggest that commonly studied phenotypes in Fmr1 KOs are sensitive to the cage effect and therefore the breeding strategy may contribute to discrepancies in the literature.This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Rasa Volianskis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, OntarioM5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, OntarioM5S 1A8, Canada
| | - Camilla J. Lundbye
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, OntarioM5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, OntarioM5S 1A8, Canada
| | - Gillian N. Petroff
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, OntarioM5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, OntarioM5S 1A8, Canada
| | - David. E. Jane
- Hello Bio Limited, Cabot Park, Avonmouth, BristolBS11 0QL, UK
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, OntarioM5G 1X5, Canada
- TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, OntarioM5S 1A8, Canada
| | - Graham L. Collingridge
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, OntarioM5G 1X5, Canada
- Department of Physiology, University of Toronto, Toronto, OntarioM5S 1A8, Canada
- TANZ Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, OntarioM5S 1A8, Canada
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Donoghue SE, Amor DJ. Intellectual disability: A potentially treatable condition. J Paediatr Child Health 2024; 60:273-278. [PMID: 38887130 DOI: 10.1111/jpc.16598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/27/2024] [Accepted: 06/04/2024] [Indexed: 06/20/2024]
Abstract
The application of genomics has greatly increased the diagnosis of specific monogenic causes of intellectual disability and improved our understanding of the neuronal processes that result in cognitive impairment. Meanwhile, families are building rare disease communities and seeking disease-specific treatments to change the trajectory of health and developmental outcomes for their children. To date, treatments for intellectual disability have focussed on metabolic disorders, where early treatment has improved cognition and neurodevelopmental outcomes. In this article, we discuss the treatment strategies that may be possible to change the neurodevelopmental outcome in a broader range of genetic forms of intellectual disability. These strategies include substrate modification, enzyme replacement therapy, gene therapy and molecular therapies. We argue that intellectual disability should now be considered a potentially treatable condition and a strong candidate for precision medicine.
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Affiliation(s)
- Sarah E Donoghue
- Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Biochemical Genetics, Victorian Clinical Genetics Services, Melbourne, Victoria, Australia
| | - David J Amor
- Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
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Schmitt LM, Arzuaga AL, Dapore A, Duncan J, Patel M, Larson JR, Erickson CA, Sweeney JA, Ragozzino ME. Parallel learning and cognitive flexibility impairments between Fmr1 knockout mice and individuals with fragile X syndrome. Front Behav Neurosci 2023; 16:1074682. [PMID: 36688132 PMCID: PMC9849779 DOI: 10.3389/fnbeh.2022.1074682] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/14/2022] [Indexed: 01/07/2023] Open
Abstract
Introduction Fragile X Syndrome (FXS) is a monogenic condition that leads to intellectual disability along with behavioral and learning difficulties. Among behavioral and learning difficulties, cognitive flexibility impairments are among the most commonly reported in FXS, which significantly impacts daily living. Despite the extensive use of the Fmr1 knockout (KO) mouse to understand molecular, synaptic and behavioral alterations related to FXS, there has been limited development of translational paradigms to understand cognitive flexibility that can be employed in both animal models and individuals with FXS to facilitate treatment development. Methods To begin addressing this limitation, a parallel set of studies were carried out that investigated probabilistic reversal learning along with other behavioral and cognitive tests in individuals with FXS and Fmr1 KO mice. Fifty-five adolescents and adults with FXS (67% male) and 34 age- and sex-matched typically developing controls (62% male) completed an initial probabilistic learning training task and a probabilistic reversal learning task. Results In males with FXS, both initial probabilistic learning and reversal learning deficits were found. However, in females with FXS, we only observed reversal learning deficits. Reversal learning deficits related to more severe psychiatric features in females with FXS, whereas increased sensitivity to negative feedback (lose:shift errors) unexpectedly appear to be adaptive in males with FXS. Male Fmr1 KO mice exhibited both an initial probabilistic learning and reversal learning deficit compared to that of wildtype (WT) mice. Female Fmr1 KO mice were selectively impaired on probabilistic reversal learning. In a prepotent response inhibition test, both male and female Fmr1 KO mice were impaired in learning to choose a non-preferred spatial location to receive a food reward compared to that of WT mice. Neither male nor female Fmr1 KO mice exhibited a change in anxiety compared to that of WT mice. Discussion Together, our findings demonstrate strikingly similar sex-dependent learning disturbances across individuals with FXS and Fmr1 KO mice. This suggests the promise of using analogous paradigms of cognitive flexibility across species that may speed treatment development to improve lives of individuals with FXS.
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Affiliation(s)
- Lauren M. Schmitt
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Anna L. Arzuaga
- Department of Psychology, University of Illinois Chicago, Chicago, IL, United States
| | - Ashley Dapore
- Department of Psychiatry, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
| | - Jason Duncan
- Department of Psychology, University of Illinois Chicago, Chicago, IL, United States
| | - Maya Patel
- Department of Psychology, University of Illinois Chicago, Chicago, IL, United States
| | - John R. Larson
- Department of Psychiatry, University of Illinois Chicago, Chicago, IL, United States
| | - Craig A. Erickson
- Department of Psychiatry, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States,Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - John A. Sweeney
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Michael E. Ragozzino
- Department of Psychology, University of Illinois Chicago, Chicago, IL, United States,*Correspondence: Michael E. Ragozzino,
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Distinct roles of astroglia and neurons in synaptic plasticity and memory. Mol Psychiatry 2022; 27:873-885. [PMID: 34642458 DOI: 10.1038/s41380-021-01332-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/17/2021] [Accepted: 09/29/2021] [Indexed: 12/17/2022]
Abstract
Long-term potentiation (LTP) in the hippocampus is the most studied form of synaptic plasticity. Temporal integration of synaptic inputs is essential in synaptic plasticity and is assumed to be achieved through Ca2+ signaling in neurons and astroglia. However, whether these two cell types play different roles in LTP remain unknown. Here, we found that through the integration of synaptic inputs, astrocyte inositol triphosphate (IP3) receptor type 2 (IP3R2)-dependent Ca2+ signaling was critical for late-phase LTP (L-LTP) but not early-phase LTP (E-LTP). Moreover, this process was mediated by astrocyte-derived brain-derived neurotrophic factor (BDNF). In contrast, neuron-derived BDNF was critical for both E-LTP and L-LTP. Importantly, the dynamic differences in BDNF secretion play a role in modulating distinct forms of LTP. Moreover, astrocyte- and neuron-derived BDNF exhibited different roles in memory. These observations enriched our knowledge of LTP and memory at the cellular level and implied distinct roles of astrocytes and neurons in information integration.
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Abstract
The structure of neuronal circuits that subserve cognitive functions in the brain is shaped and refined throughout development and into adulthood. Evidence from human and animal studies suggests that the cellular and synaptic substrates of these circuits are atypical in neuropsychiatric disorders, indicating that altered structural plasticity may be an important part of the disease biology. Advances in genetics have redefined our understanding of neuropsychiatric disorders and have revealed a spectrum of risk factors that impact pathways known to influence structural plasticity. In this Review, we discuss the importance of recent genetic findings on the different mechanisms of structural plasticity and propose that these converge on shared pathways that can be targeted with novel therapeutics.
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Zafarullah M, Tassone F. Molecular Biomarkers in Fragile X Syndrome. Brain Sci 2019; 9:E96. [PMID: 31035599 PMCID: PMC6562871 DOI: 10.3390/brainsci9050096] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 01/01/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability (ID) and a known monogenic cause of autism spectrum disorder (ASD). It is a trinucleotide repeat disorder, in which more than 200 CGG repeats in the 5' untranslated region (UTR) of the fragile X mental retardation 1 (FMR1) gene causes methylation of the promoter with consequent silencing of the gene, ultimately leading to the loss of the encoded fragile X mental retardation 1 protein, FMRP. FMRP is an RNA binding protein that plays a primary role as a repressor of translation of various mRNAs, many of which are involved in the maintenance and development of neuronal synaptic function and plasticity. In addition to intellectual disability, patients with FXS face several behavioral challenges, including anxiety, hyperactivity, seizures, repetitive behavior, and problems with executive and language performance. Currently, there is no cure or approved medication for the treatment of the underlying causes of FXS, but in the past few years, our knowledge about the proteins and pathways that are dysregulated by the loss of FMRP has increased, leading to clinical trials and to the path of developing molecular biomarkers for identifying potential targets for therapies. In this paper, we review candidate molecular biomarkers that have been identified in preclinical studies in the FXS mouse animal model and are now under validation for human applications or have already made their way to clinical trials.
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Affiliation(s)
- Marwa Zafarullah
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, Sacramento, 95817 CA, USA.
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, Sacramento, 95817 CA, USA.
- MIND Institute, University of California Davis Medical Center, Sacramento, 95817 CA, USA.
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Jacquemont S, Pacini L, Jønch AE, Cencelli G, Rozenberg I, He Y, D'Andrea L, Pedini G, Eldeeb M, Willemsen R, Gasparini F, Tassone F, Hagerman R, Gomez-Mancilla B, Bagni C. Protein synthesis levels are increased in a subset of individuals with fragile X syndrome. Hum Mol Genet 2019; 27:2039-2051. [PMID: 29590342 PMCID: PMC5985734 DOI: 10.1093/hmg/ddy099] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/15/2018] [Indexed: 12/15/2022] Open
Abstract
Fragile X syndrome (FXS) is a monogenic form of intellectual disability and autism spectrum disorder caused by the absence of the fragile X mental retardation protein (FMRP). In biological models for the disease, this leads to upregulated mRNA translation and as a consequence, deficits in synaptic architecture and plasticity. Preclinical studies revealed that pharmacological interventions restore those deficits, which are thought to mediate the FXS cognitive and behavioral symptoms. Here, we characterized the de novo rate of protein synthesis in patients with FXS and their relationship with clinical severity. We measured the rate of protein synthesis in fibroblasts derived from 32 individuals with FXS and from 17 controls as well as in fibroblasts and primary neurons of 27 Fmr1 KO mice and 20 controls. Here, we show that levels of protein synthesis are increased in fibroblasts of individuals with FXS and Fmr1 KO mice. However, this cellular phenotype displays a broad distribution and a proportion of fragile X individuals and Fmr1 KO mice do not show increased levels of protein synthesis, having measures in the normal range. Because the same Fmr1 KO animal measures in fibroblasts predict those in neurons we suggest the validity of this peripheral biomarker. Our study offers a potential explanation for the comprehensive drug development program undertaken thus far yielding negative results and suggests that a significant proportion, but not all individuals with FXS, may benefit from the reduction of excessive levels of protein synthesis.
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Affiliation(s)
- Sébastien Jacquemont
- Sainte-Justine University Hospital Research Centre, Montreal, QC H3T 1C5.,University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Laura Pacini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Aia E Jønch
- Department of Clinical Genetics, Odense University Hospital.,Human Genetics, Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark
| | - Giulia Cencelli
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Izabela Rozenberg
- Neuroscience Translational Medicine, Novartis Institutes for Biomedical Research, Novartis Pharma AG, 4056 Basel, Switzerland
| | - Yunsheng He
- Biomarker Development, Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA
| | - Laura D'Andrea
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Giorgia Pedini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Marwa Eldeeb
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis Medical Center, Sacramento, CA 95817, USA
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus Medical Center, 1738, 3000DR Rotterdam, The Netherlands
| | - Fabrizio Gasparini
- Neuroscience Discovery, Novartis Institutes for BioMedical Research, 4002 Basel, Switzerland
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine and Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, Sacramento, CA 95817, USA
| | - Randi Hagerman
- Department of Pediatric and Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, School of Medicine, Sacramento, CA 95817, USA
| | - Baltazar Gomez-Mancilla
- Neuroscience Translational Medicine, Novartis Institutes for Biomedical Research, Novartis Pharma AG, 4056 Basel, Switzerland.,Department of Neurology and Neurosurgery, McGill University, Montreal, QC H3A 0G4, Canada
| | - Claudia Bagni
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy.,Department of Fundamental Neuroscience, University of Lausanne, 1005 Lausanne, Switzerland
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Lundbye CJ, Toft AKH, Banke TG. Inhibition of GluN2A NMDA receptors ameliorates synaptic plasticity deficits in the Fmr1 -/y mouse model. J Physiol 2018; 596:5017-5031. [PMID: 30132892 DOI: 10.1113/jp276304] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 08/20/2018] [Indexed: 02/06/2023] Open
Abstract
KEY POINTS Fragile X syndrome (FXS) is a genetic condition that is the most common form of inherited intellectual impairment and causes a range of neurodevelopmental complications including learning disabilities and intellectual disability and shares many characteristics with autism spectrum disorder (ASD). In the FXS mouse model, Fmr1-/y , impaired synaptic plasticity was restored by pharmacologically inhibiting GluN2A-containing NMDA receptors but not GluN2B-containing receptors. Similar results were obtained by crossing Fmr1-/y with GluN2A knock-out (Grin2A-/- ) mice. These results suggest that dampening the elevated levels of GluN2A-containing NMDA receptors in Fmr1-/y mice has the potential to restore hyperexcitability of the neural circuitry to (a more) normal-like level of brain activity. ABSTRACT NMDA receptors (NMDARs) play important roles in synaptic plasticity at central excitatory synapses, and dysregulation of their function may lead to severe disorders such Fragile X syndrome (FXS). FXS is caused by transcriptional silencing of the FMR1 gene followed by lack of the encoding protein. Here we examined the effects of pharmacological and genetic manipulation of hippocampal NMDAR functions in long-term potentiation (LTP) and depression (LTD). We found impaired NMDAR-dependent LTP in the Fmr1-deficient mice, which could be fully restored when GluN2A-containing NMDARs was pharmacological inhibited. Interestingly, similar LTP effects were observed when the GluN2A gene (Grin2a) was deleted in Fmr1-/y mice (Fmr1-/y /Grin2a-/- double knockout). In addition, GluN2A inhibition improved elevated mGluR5-dependent LTD to normal level in the Fmr1-/y mouse. These findings suggest that GluN2A is a promising target in FXS research that could help us better understand the disorder.
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Affiliation(s)
- Camilla J Lundbye
- Institute of Biomedicine - Physiology, Aarhus University, DK-8000, Aarhus, Denmark
| | - Anna Karina H Toft
- Institute of Biomedicine - Physiology, Aarhus University, DK-8000, Aarhus, Denmark
| | - Tue G Banke
- Institute of Biomedicine - Physiology, Aarhus University, DK-8000, Aarhus, Denmark
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Dahlhaus R. Of Men and Mice: Modeling the Fragile X Syndrome. Front Mol Neurosci 2018; 11:41. [PMID: 29599705 PMCID: PMC5862809 DOI: 10.3389/fnmol.2018.00041] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/31/2018] [Indexed: 12/26/2022] Open
Abstract
The Fragile X Syndrome (FXS) is one of the most common forms of inherited intellectual disability in all human societies. Caused by the transcriptional silencing of a single gene, the fragile x mental retardation gene FMR1, FXS is characterized by a variety of symptoms, which range from mental disabilities to autism and epilepsy. More than 20 years ago, a first animal model was described, the Fmr1 knock-out mouse. Several other models have been developed since then, including conditional knock-out mice, knock-out rats, a zebrafish and a drosophila model. Using these model systems, various targets for potential pharmaceutical treatments have been identified and many treatments have been shown to be efficient in preclinical studies. However, all attempts to turn these findings into a therapy for patients have failed thus far. In this review, I will discuss underlying difficulties and address potential alternatives for our future research.
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Affiliation(s)
- Regina Dahlhaus
- Institute for Biochemistry, Emil-Fischer Centre, University of Erlangen-Nürnberg, Erlangen, Germany
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Drug development for neurodevelopmental disorders: lessons learned from fragile X syndrome. Nat Rev Drug Discov 2017; 17:280-299. [PMID: 29217836 DOI: 10.1038/nrd.2017.221] [Citation(s) in RCA: 218] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Neurodevelopmental disorders such as fragile X syndrome (FXS) result in lifelong cognitive and behavioural deficits and represent a major public health burden. FXS is the most frequent monogenic form of intellectual disability and autism, and the underlying pathophysiology linked to its causal gene, FMR1, has been the focus of intense research. Key alterations in synaptic function thought to underlie this neurodevelopmental disorder have been characterized and rescued in animal models of FXS using genetic and pharmacological approaches. These robust preclinical findings have led to the implementation of the most comprehensive drug development programme undertaken thus far for a genetically defined neurodevelopmental disorder, including phase IIb trials of metabotropic glutamate receptor 5 (mGluR5) antagonists and a phase III trial of a GABAB receptor agonist. However, none of the trials has been able to unambiguously demonstrate efficacy, and they have also highlighted the extent of the knowledge gaps in drug development for FXS and other neurodevelopmental disorders. In this Review, we examine potential issues in the previous studies and future directions for preclinical and clinical trials. FXS is at the forefront of efforts to develop drugs for neurodevelopmental disorders, and lessons learned in the process will also be important for such disorders.
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Martinez LA, Tejada-Simon MV. Pharmacological Rescue of Hippocampal Fear Learning Deficits in Fragile X Syndrome. Mol Neurobiol 2017; 55:5951-5961. [DOI: 10.1007/s12035-017-0819-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/02/2017] [Indexed: 11/28/2022]
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Increased Training Intensity Induces Proper Membrane Localization of Actin Remodeling Proteins in the Hippocampus Preventing Cognitive Deficits: Implications for Fragile X Syndrome. Mol Neurobiol 2017; 55:4529-4542. [DOI: 10.1007/s12035-017-0666-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/19/2017] [Indexed: 10/19/2022]
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13
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Tabet R, Vitale N, Moine H. Fragile X syndrome: Are signaling lipids the missing culprits? Biochimie 2016; 130:188-194. [PMID: 27597551 DOI: 10.1016/j.biochi.2016.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/01/2016] [Indexed: 10/21/2022]
Abstract
Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and autism. FXS results from the absence of FMRP, an RNA binding protein associated to ribosomes that influences the translation of specific mRNAs in post-synaptic compartments of neurons. The main molecular consequence of the absence of FMRP is an excessive translation of neuronal protein in several areas of the brain. This local protein synthesis deregulation is proposed to underlie the defect in synaptic plasticity responsible for FXS. Recent findings in neurons of the fragile X mouse model (Fmr1-KO) uncovered another consequence of the lack of FMRP: a deregulation of the diacylglycerol (DAG)/phosphatidic acid (PA) homeostasis. DAG and PA are two interconvertible lipids that influence membrane architecture and that act as essential signaling molecules that activate various downstream effectors, including master regulators of local protein synthesis and actin polymerization. As a consequence, DAG and PA govern a variety of cellular processes, including cell proliferation, vesicle/membrane trafficking and cytoskeletal organization. At the synapse, the level of these lipids is proposed to influence the synaptic activation status. FMRP appears as a master regulator of this neuronal process by controlling the translation of a diacylglycerol kinase enzyme that converts DAG into PA. The deregulated levels of DAG and PA caused by the absence of FMRP could represent a novel therapeutic target for the treatment of FXS.
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Affiliation(s)
- Ricardos Tabet
- Mass General Institute for Neurodegenerative Disease, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Hervé Moine
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67084 Strasbourg, France.
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14
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Tabet R, Moutin E, Becker JAJ, Heintz D, Fouillen L, Flatter E, Krężel W, Alunni V, Koebel P, Dembélé D, Tassone F, Bardoni B, Mandel JL, Vitale N, Muller D, Le Merrer J, Moine H. Fragile X Mental Retardation Protein (FMRP) controls diacylglycerol kinase activity in neurons. Proc Natl Acad Sci U S A 2016; 113:E3619-28. [PMID: 27233938 PMCID: PMC4932937 DOI: 10.1073/pnas.1522631113] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fragile X syndrome (FXS) is caused by the absence of the Fragile X Mental Retardation Protein (FMRP) in neurons. In the mouse, the lack of FMRP is associated with an excessive translation of hundreds of neuronal proteins, notably including postsynaptic proteins. This local protein synthesis deregulation is proposed to underlie the observed defects of glutamatergic synapse maturation and function and to affect preferentially the hundreds of mRNA species that were reported to bind to FMRP. How FMRP impacts synaptic protein translation and which mRNAs are most important for the pathology remain unclear. Here we show by cross-linking immunoprecipitation in cortical neurons that FMRP is mostly associated with one unique mRNA: diacylglycerol kinase kappa (Dgkκ), a master regulator that controls the switch between diacylglycerol and phosphatidic acid signaling pathways. The absence of FMRP in neurons abolishes group 1 metabotropic glutamate receptor-dependent DGK activity combined with a loss of Dgkκ expression. The reduction of Dgkκ in neurons is sufficient to cause dendritic spine abnormalities, synaptic plasticity alterations, and behavior disorders similar to those observed in the FXS mouse model. Overexpression of Dgkκ in neurons is able to rescue the dendritic spine defects of the Fragile X Mental Retardation 1 gene KO neurons. Together, these data suggest that Dgkκ deregulation contributes to FXS pathology and support a model where FMRP, by controlling the translation of Dgkκ, indirectly controls synaptic proteins translation and membrane properties by impacting lipid signaling in dendritic spine.
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Affiliation(s)
- Ricardos Tabet
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Enora Moutin
- Department of Basic Neuroscience, University of Geneva, 1211 Geneva 4, Switzerland
| | - Jérôme A J Becker
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Dimitri Heintz
- Institut de Biologie Moléculaire des Plantes, Plateforme Métabolomique, Unité Propre de Recherche (UPR) 2357 CNRS, Université de Strasbourg, 67082 Strasbourg, France
| | - Laetitia Fouillen
- Laboratoire de Biogènese Membranaire; UMR 5200 CNRS, Plateforme Métabolome, Université de Bordeaux, 33140 Villenave D'Ornon, France
| | - Eric Flatter
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Wojciech Krężel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Violaine Alunni
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Pascale Koebel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Doulaye Dembélé
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California Davis Medical Center, Sacramento, CA 95817
| | - Barbara Bardoni
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, University of Nice Sophia-Antipolis, CNRS Laboratoire International Associé (LIA) Neogenex, 06560 Valbonne, France
| | - Jean-Louis Mandel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France; Collège de France, 75005 Paris, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, UPR3212 CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Dominique Muller
- Department of Basic Neuroscience, University of Geneva, 1211 Geneva 4, Switzerland
| | - Julie Le Merrer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France
| | - Hervé Moine
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France;
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15
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Wang Y, Hersheson J, Lopez D, Hammer M, Liu Y, Lee KH, Pinto V, Seinfeld J, Wiethoff S, Sun J, Amouri R, Hentati F, Baudry N, Tran J, Singleton AB, Coutelier M, Brice A, Stevanin G, Durr A, Bi X, Houlden H, Baudry M. Defects in the CAPN1 Gene Result in Alterations in Cerebellar Development and Cerebellar Ataxia in Mice and Humans. Cell Rep 2016; 16:79-91. [PMID: 27320912 DOI: 10.1016/j.celrep.2016.05.044] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 04/14/2016] [Accepted: 05/10/2016] [Indexed: 11/16/2022] Open
Abstract
A CAPN1 missense mutation in Parson Russell Terrier dogs is associated with spinocerebellar ataxia. We now report that homozygous or heterozygous CAPN1-null mutations in humans result in cerebellar ataxia and limb spasticity in four independent pedigrees. Calpain-1 knockout (KO) mice also exhibit a mild form of ataxia due to abnormal cerebellar development, including enhanced neuronal apoptosis, decreased number of cerebellar granule cells, and altered synaptic transmission. Enhanced apoptosis is due to absence of calpain-1-mediated cleavage of PH domain and leucine-rich repeat protein phosphatase 1 (PHLPP1), which results in inhibition of the Akt pro-survival pathway in developing granule cells. Injection of neonatal mice with the indirect Akt activator, bisperoxovanadium, or crossing calpain-1 KO mice with PHLPP1 KO mice prevented increased postnatal cerebellar granule cell apoptosis and restored granule cell density and motor coordination in adult mice. Thus, mutations in CAPN1 are an additional cause of ataxia in mammals, including humans.
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Affiliation(s)
- Yubin Wang
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Joshua Hersheson
- The National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Dulce Lopez
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Monia Hammer
- Department of Molecular Neurobiology and Neuropathology, National Institute of Neurology, La Rabta, Tunis 1007, Tunisia; Laboratory of Neurogenetics, National Institutes of Health, Bethesda 20892, MD, USA
| | - Yan Liu
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Ka-Hung Lee
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Vanessa Pinto
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Jeff Seinfeld
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Sarah Wiethoff
- The National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; Center for Neurology and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Jiandong Sun
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Rim Amouri
- Department of Molecular Neurobiology and Neuropathology, National Institute of Neurology, La Rabta, Tunis 1007, Tunisia
| | - Faycal Hentati
- Department of Molecular Neurobiology and Neuropathology, National Institute of Neurology, La Rabta, Tunis 1007, Tunisia
| | - Neema Baudry
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Jennifer Tran
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Andrew B Singleton
- Laboratory of Neurogenetics, National Institutes of Health, Bethesda 20892, MD, USA
| | - Marie Coutelier
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités, Université Pierre et Marie Curie Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, 75013 Paris, France; Laboratory of Human Molecular Genetics, de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium; Ecole Pratique des Hautes Etudes (EPHE), Paris Sciences et Lettres (PSL) Research University, 75013 Paris, France
| | - Alexis Brice
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités, Université Pierre et Marie Curie Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, 75013 Paris, France; Centre de Référence de Neurogénétique, Hôpital de la Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, 75013 Paris, France
| | - Giovanni Stevanin
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités, Université Pierre et Marie Curie Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, 75013 Paris, France; Ecole Pratique des Hautes Etudes (EPHE), Paris Sciences et Lettres (PSL) Research University, 75013 Paris, France; Centre de Référence de Neurogénétique, Hôpital de la Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, 75013 Paris, France
| | - Alexandra Durr
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités, Université Pierre et Marie Curie Paris 06 UMRS 1127, Institut du Cerveau et de la Moelle épinière, 75013 Paris, France; Centre de Référence de Neurogénétique, Hôpital de la Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, 75013 Paris, France
| | - Xiaoning Bi
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Henry Houlden
- The National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
| | - Michel Baudry
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA.
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16
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Gross C, Hoffmann A, Bassell GJ, Berry-Kravis EM. Therapeutic Strategies in Fragile X Syndrome: From Bench to Bedside and Back. Neurotherapeutics 2015; 12:584-608. [PMID: 25986746 PMCID: PMC4489963 DOI: 10.1007/s13311-015-0355-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Fragile X syndrome (FXS), an inherited intellectual disability often associated with autism, is caused by the loss of expression of the fragile X mental retardation protein. Tremendous progress in basic, preclinical, and translational clinical research has elucidated a variety of molecular-, cellular-, and system-level defects in FXS. This has led to the development of several promising therapeutic strategies, some of which have been tested in larger-scale controlled clinical trials. Here, we will summarize recent advances in understanding molecular functions of fragile X mental retardation protein beyond the well-known role as an mRNA-binding protein, and will describe current developments and emerging limitations in the use of the FXS mouse model as a preclinical tool to identify therapeutic targets. We will review the results of recent clinical trials conducted in FXS that were based on some of the preclinical findings, and discuss how the observed outcomes and obstacles will inform future therapy development in FXS and other autism spectrum disorders.
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Affiliation(s)
- Christina Gross
- />Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229 USA
| | - Anne Hoffmann
- />Department of Pediatrics, Rush University Medical Center, Chicago, IL 60612 USA
| | - Gary J. Bassell
- />Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Elizabeth M. Berry-Kravis
- />Departments of Pediatrics, Neurological Sciences, Biochemistry, Rush University Medical Center, Chicago, IL 60612 USA
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17
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Neuhofer D, Henstridge CM, Dudok B, Sepers M, Lassalle O, Katona I, Manzoni OJ. Functional and structural deficits at accumbens synapses in a mouse model of Fragile X. Front Cell Neurosci 2015; 9:100. [PMID: 25859182 PMCID: PMC4374460 DOI: 10.3389/fncel.2015.00100] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/07/2015] [Indexed: 12/26/2022] Open
Abstract
Fragile X is the most common cause of inherited intellectual disability and a leading cause of autism. The disease is caused by mutation of a single X-linked gene called fmr1 that codes for the Fragile X mental retardation protein (FMRP), a 71 kDa protein, which acts mainly as a translation inhibitor. Fragile X patients suffer from cognitive and emotional deficits that coincide with abnormalities in dendritic spines. Changes in spine morphology are often associated with altered excitatory transmission and long-term plasticity, the most prominent deficit in fmr1-/y mice. The nucleus accumbens, a central part of the mesocortico-limbic reward pathway, is now considered as a core structure in the control of social behaviors. Although the socio-affective impairments observed in Fragile X suggest dysfunctions in the accumbens, the impact of the lack of FMRP on accumbal synapses has scarcely been studied. Here we report for the first time a new spike timing-dependent plasticity paradigm that reliably triggers NMDAR-dependent long-term potentiation (LTP) of excitatory afferent inputs of medium spiny neurons (MSN) in the nucleus accumbens core region. Notably, we discovered that this LTP was completely absent in fmr1-/y mice. In the fmr1-/y accumbens intrinsic membrane properties of MSNs and basal excitatory neurotransmission remained intact in the fmr1-/y accumbens but the deficit in LTP was accompanied by an increase in evoked AMPA/NMDA ratio and a concomitant reduction of spontaneous NMDAR-mediated currents. In agreement with these physiological findings, we found significantly more filopodial spines in fmr1-/y mice by using an ultrastructural electron microscopic analysis of accumbens core medium spiny neuron spines. Surprisingly, spine elongation was specifically due to the longer longitudinal axis and larger area of spine necks, whereas spine head morphology and postsynaptic density size on spine heads remained unaffected in the fmr1-/y accumbens. These findings together reveal new structural and functional synaptic deficits in Fragile X.
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Affiliation(s)
- Daniela Neuhofer
- INSERM U901 Marseille, France ; INMED Marseille, France ; Université de Aix-Marseille, UMR S901 Marseille, France
| | - Christopher M Henstridge
- Momentum Laboratory of Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Barna Dudok
- Momentum Laboratory of Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary ; School of Ph.D. Studies, Semmelweis University Budapest, Hungary
| | - Marja Sepers
- Department of Psychiatry, University of British Columbia Vancouver, Canada
| | - Olivier Lassalle
- INSERM U901 Marseille, France ; INMED Marseille, France ; Université de Aix-Marseille, UMR S901 Marseille, France
| | - István Katona
- Momentum Laboratory of Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Olivier J Manzoni
- INSERM U901 Marseille, France ; INMED Marseille, France ; Université de Aix-Marseille, UMR S901 Marseille, France
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18
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Yuan L, Seong E, Beuscher JL, Arikkath J. δ-Catenin Regulates Spine Architecture via Cadherin and PDZ-dependent Interactions. J Biol Chem 2015; 290:10947-57. [PMID: 25724647 DOI: 10.1074/jbc.m114.632679] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Indexed: 12/14/2022] Open
Abstract
The ability of neurons to maintain spine architecture and modulate it in response to synaptic activity is a crucial component of the cellular machinery that underlies information storage in pyramidal neurons of the hippocampus. Here we show a critical role for δ-catenin, a component of the cadherin-catenin cell adhesion complex, in regulating spine head width and length in pyramidal neurons of the hippocampus. The loss of Ctnnd2, the gene encoding δ-catenin, has been associated with the intellectual disability observed in the cri du chat syndrome, suggesting that the functional roles of δ-catenin are vital for neuronal integrity and higher order functions. We demonstrate that loss of δ-catenin in a mouse model or knockdown of δ-catenin in pyramidal neurons compromises spine head width and length, without altering spine dynamics. This is accompanied by a reduction in the levels of synaptic N-cadherin. The ability of δ-catenin to modulate spine architecture is critically dependent on its ability to interact with cadherin and PDZ domain-containing proteins. We propose that loss of δ-catenin during development perturbs synaptic architecture leading to developmental aberrations in neural circuit formation that contribute to the learning disabilities in a mouse model and humans with cri du chat syndrome.
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Affiliation(s)
- Li Yuan
- From the Department of Pharmacology and Experimental Neuroscience
| | - Eunju Seong
- Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - James L Beuscher
- Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - Jyothi Arikkath
- From the Department of Pharmacology and Experimental Neuroscience, Developmental Neuroscience, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198
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19
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Wang H, Pati S, Pozzo-Miller L, Doering LC. Targeted pharmacological treatment of autism spectrum disorders: fragile X and Rett syndromes. Front Cell Neurosci 2015; 9:55. [PMID: 25767435 PMCID: PMC4341567 DOI: 10.3389/fncel.2015.00055] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 02/05/2015] [Indexed: 12/27/2022] Open
Abstract
Autism spectrum disorders (ASDs) are genetically and clinically heterogeneous and lack effective medications to treat their core symptoms. Studies of syndromic ASDs caused by single gene mutations have provided insights into the pathophysiology of autism. Fragile X and Rett syndromes belong to the syndromic ASDs in which preclinical studies have identified rational targets for drug therapies focused on correcting underlying neural dysfunction. These preclinical discoveries are increasingly translating into exciting human clinical trials. Since there are significant molecular and neurobiological overlaps among ASDs, targeted treatments developed for fragile X and Rett syndromes may be helpful for autism of different etiologies. Here, we review the targeted pharmacological treatment of fragile X and Rett syndromes and discuss related issues in both preclinical studies and clinical trials of potential therapies for the diseases.
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Affiliation(s)
- Hansen Wang
- Faculty of Medicine, University of Toronto, 1 King's College Circle Toronto, ON, Canada
| | - Sandipan Pati
- Department of Neurology, Epilepsy Division, The University of Alabama at Birmingham Birmingham, AL, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology, Civitan International Research Center, The University of Alabama at Birmingham Birmingham, AL, USA
| | - Laurie C Doering
- Faculty of Health Sciences, Department of Pathology and Molecular Medicine, McMaster University Hamilton, ON, Canada
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20
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Affiliation(s)
- Scott Thompson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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21
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Bernardinelli Y, Nikonenko I, Muller D. Structural plasticity: mechanisms and contribution to developmental psychiatric disorders. Front Neuroanat 2014; 8:123. [PMID: 25404897 PMCID: PMC4217507 DOI: 10.3389/fnana.2014.00123] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 10/14/2014] [Indexed: 01/31/2023] Open
Abstract
Synaptic plasticity mechanisms are usually discussed in terms of changes in synaptic strength. The capacity of excitatory synapses to rapidly modify the membrane expression of glutamate receptors in an activity-dependent manner plays a critical role in learning and memory processes by re-distributing activity within neuronal networks. Recent work has however also shown that functional plasticity properties are associated with a rewiring of synaptic connections and a selective stabilization of activated synapses. These structural aspects of plasticity have the potential to continuously modify the organization of synaptic networks and thereby introduce specificity in the wiring diagram of cortical circuits. Recent work has started to unravel some of the molecular mechanisms that underlie these properties of structural plasticity, highlighting an important role of signaling pathways that are also major candidates for contributing to developmental psychiatric disorders. We review here some of these recent advances and discuss the hypothesis that alterations of structural plasticity could represent a common mechanism contributing to the cognitive and functional defects observed in diseases such as intellectual disability, autism spectrum disorders and schizophrenia.
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Affiliation(s)
- Yann Bernardinelli
- Department of Basic Neurosciences, University of Geneva Medical School Geneva, Switzerland
| | - Irina Nikonenko
- Department of Basic Neurosciences, University of Geneva Medical School Geneva, Switzerland
| | - Dominique Muller
- Department of Basic Neurosciences, University of Geneva Medical School Geneva, Switzerland
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22
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Caroni P, Chowdhury A, Lahr M. Synapse rearrangements upon learning: from divergent-sparse connectivity to dedicated sub-circuits. Trends Neurosci 2014; 37:604-14. [PMID: 25257207 DOI: 10.1016/j.tins.2014.08.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/26/2014] [Accepted: 08/27/2014] [Indexed: 01/24/2023]
Abstract
Learning can involve formation of new synapses and loss of synapses, providing memory traces of learned skills. Recent findings suggest that these synapse rearrangements reflect assembly of task-related sub-circuits from initially broadly distributed and sparse connectivity in the brain. These local circuit remodeling processes involve rapid emergence of synapses upon learning, followed by protracted validation involving strengthening of some new synapses, and selective elimination of others. The timing of these consolidation processes can vary. Here, we review these findings, focusing on how molecular/cellular mechanisms of synapse assembly, strengthening, and elimination might interface with circuit/system mechanisms of learning and memory consolidation. An integrated understanding of these learning-related processes should provide a better basis to elucidate how experience, genetic background, and disease influence brain function.
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Affiliation(s)
- Pico Caroni
- Friedrich Miescher Institut, Basel, Switzerland.
| | | | - Maria Lahr
- Friedrich Miescher Institut, Basel, Switzerland
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23
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Hébert B, Pietropaolo S, Même S, Laudier B, Laugeray A, Doisne N, Quartier A, Lefeuvre S, Got L, Cahard D, Laumonnier F, Crusio WE, Pichon J, Menuet A, Perche O, Briault S. Rescue of fragile X syndrome phenotypes in Fmr1 KO mice by a BKCa channel opener molecule. Orphanet J Rare Dis 2014; 9:124. [PMID: 25079250 PMCID: PMC4237919 DOI: 10.1186/s13023-014-0124-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 07/21/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Fragile X Syndrome (FXS) is the most common form of inherited intellectual disability and is also associated with autism spectrum disorders. Previous studies implicated BKCa channels in the neuropathogenesis of FXS, but the main question was whether pharmacological BKCa stimulation would be able to rescue FXS neurobehavioral phenotypes. METHODS AND RESULTS We used a selective BKCa channel opener molecule (BMS-204352) to address this issue in Fmr1 KO mice, modeling the FXS pathophysiology. In vitro, acute BMS-204352 treatment (10 μM) restored the abnormal dendritic spine phenotype. In vivo, a single injection of BMS-204352 (2 mg/kg) rescued the hippocampal glutamate homeostasis and the behavioral phenotype. Indeed, disturbances in social recognition and interaction, non-social anxiety, and spatial memory were corrected by BMS-204352 in Fmr1 KO mice. CONCLUSION These results demonstrate that the BKCa channel is a new therapeutic target for FXS. We show that BMS-204352 rescues a broad spectrum of behavioral impairments (social, emotional and cognitive) in an animal model of FXS. This pharmacological molecule might open new ways for FXS therapy.
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24
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Activity-dependent structural plasticity of perisynaptic astrocytic domains promotes excitatory synapse stability. Curr Biol 2014; 24:1679-88. [PMID: 25042585 DOI: 10.1016/j.cub.2014.06.025] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/05/2014] [Accepted: 06/10/2014] [Indexed: 11/21/2022]
Abstract
BACKGROUND Excitatory synapses in the CNS are highly dynamic structures that can show activity-dependent remodeling and stabilization in response to learning and memory. Synapses are enveloped with intricate processes of astrocytes known as perisynaptic astrocytic processes (PAPs). PAPs are motile structures displaying rapid actin-dependent movements and are characterized by Ca(2+) elevations in response to neuronal activity. Despite a debated implication in synaptic plasticity, the role of both Ca(2+) events in astrocytes and PAP morphological dynamics remain unclear. RESULTS In the hippocampus, we found that PAPs show extensive structural plasticity that is regulated by synaptic activity through astrocytic metabotropic glutamate receptors and intracellular calcium signaling. Synaptic activation that induces long-term potentiation caused a transient PAP motility increase leading to an enhanced astrocytic coverage of the synapse. Selective activation of calcium signals in individual PAPs using exogenous metabotropic receptor expression and two-photon uncaging reproduced these effects and enhanced spine stability. In vivo imaging in the somatosensory cortex of adult mice revealed that increased neuronal activity through whisker stimulation similarly elevates PAP movement. This in vivo PAP motility correlated with spine coverage and was predictive of spine stability. CONCLUSIONS This study identifies a novel bidirectional interaction between synapses and astrocytes, in which synaptic activity and synaptic potentiation regulate PAP structural plasticity, which in turn determines the fate of the synapse. This mechanism may represent an important contribution of astrocytes to learning and memory processes.
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