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Pasciuto E, Borrie SC, Kanellopoulos AK, Santos AR, Cappuyns E, D'Andrea L, Pacini L, Bagni C. Autism Spectrum Disorders: Translating human deficits into mouse behavior. Neurobiol Learn Mem 2015. [PMID: 26220900 DOI: 10.1016/j.nlm.2015.07.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Autism Spectrum Disorders are a heterogeneous group of neurodevelopmental disorders, with rising incidence but little effective therapeutic intervention available. Currently two main clinical features are described to diagnose ASDs: impaired social interaction and communication, and repetitive behaviors. Much work has focused on understanding underlying causes of ASD by generating animal models of the disease, in the hope of discovering signaling pathways and cellular targets for drug intervention. Here we review how ASD behavioral phenotypes can be modeled in the mouse, the most common animal model currently in use in this field, and discuss examples of genetic mouse models of ASD with behavioral features that recapitulate various symptoms of ASD.
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Affiliation(s)
- E Pasciuto
- KU Leuven, Center for Human Genetics, Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium; VIB Center for the Biology of Disease, Leuven, Belgium
| | - S C Borrie
- KU Leuven, Center for Human Genetics, Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium; VIB Center for the Biology of Disease, Leuven, Belgium
| | - A K Kanellopoulos
- KU Leuven, Center for Human Genetics, Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium; VIB Center for the Biology of Disease, Leuven, Belgium
| | - A R Santos
- KU Leuven, Center for Human Genetics, Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium; VIB Center for the Biology of Disease, Leuven, Belgium
| | - E Cappuyns
- KU Leuven, Center for Human Genetics, Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium; VIB Center for the Biology of Disease, Leuven, Belgium
| | - L D'Andrea
- University of Rome Tor Vergata, Department of Biomedicine and Prevention, Rome, Italy
| | - L Pacini
- University of Rome Tor Vergata, Department of Biomedicine and Prevention, Rome, Italy
| | - C Bagni
- KU Leuven, Center for Human Genetics, Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium; VIB Center for the Biology of Disease, Leuven, Belgium; University of Rome Tor Vergata, Department of Biomedicine and Prevention, Rome, Italy.
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52
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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: 7.6] [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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Abstract
Pharmacologic treatments targeting specific molecular mechanisms relevant for autism spectrum disorder (ASD) are beginning to emerge in early drug development. This article reviews the evidence for the disruption of glutamatergic neurotransmission in animal models of social deficits and summarizes key pre-clinical and clinical efforts in developing pharmacologic interventions based on modulation of glutamatergic systems in individuals with ASD. Understanding the pathobiology of the glutamatergic system has led to the development of new investigational treatments for individuals with ASD. Specific examples of medications that modulate the glutamatergic system in pre-clinical and clinical studies are described. Finally, we discuss the limitations of current strategies and future opportunities in developing medications targeting the glutamatergic system for treating individuals with ASD.
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Martin HGS, Lassalle O, Brown JT, Manzoni OJ. Age-Dependent Long-Term Potentiation Deficits in the Prefrontal Cortex of the Fmr1 Knockout Mouse Model of Fragile X Syndrome. Cereb Cortex 2015; 26:2084-2092. [PMID: 25750254 DOI: 10.1093/cercor/bhv031] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The most common inherited monogenetic cause of intellectual disability is Fragile X syndrome (FXS). The clinical symptoms of FXS evolve with age during adulthood; however, neurophysiological data exploring this phenomenon are limited. The Fmr1 knockout (Fmr1KO) mouse models FXS, but studies in these mice of prefrontal cortex (PFC) function are underrepresented, and aging linked data are absent. We studied synaptic physiology and activity-dependent synaptic plasticity in the medial PFC of Fmr1KO mice from 2 to 12 months. In young adult Fmr1KO mice, NMDA receptor (NMDAR)-mediated long-term potentiation (LTP) is intact; however, in 12-month-old mice this LTP is impaired. In parallel, there was an increase in the AMPAR/NMDAR ratio and a concomitant decrease of synaptic NMDAR currents in 12-month-old Fmr1KO mice. We found that acute pharmacological blockade of mGlu5 receptor in 12-month-old Fmr1KO mice restored a normal AMPAR/NMDAR ratio and LTP. Taken together, the data reveal an age-dependent deficit in LTP in Fmr1KO mice, which may correlate to some of the complex age-related deficits in FXS.
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Affiliation(s)
- Henry G S Martin
- INSERM U901, Marseille 13009, France.,INMED, Marseille 13009, France.,Université de Aix-Marseille, UMR S901, Marseille, France
| | - Olivier Lassalle
- INSERM U901, Marseille 13009, France.,INMED, Marseille 13009, France.,Université de Aix-Marseille, UMR S901, Marseille, France
| | - Jonathan T Brown
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Olivier J Manzoni
- INSERM U901, Marseille 13009, France.,INMED, Marseille 13009, France.,Université de Aix-Marseille, UMR S901, Marseille, France
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55
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de Esch C, van den Berg W, Buijsen R, Jaafar I, Nieuwenhuizen-Bakker I, Gasparini F, Kushner S, Willemsen R. Fragile X mice have robust mGluR5-dependent alterations of social behaviour in the Automated Tube Test. Neurobiol Dis 2015; 75:31-9. [DOI: 10.1016/j.nbd.2014.12.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 12/08/2014] [Accepted: 12/23/2014] [Indexed: 11/16/2022] Open
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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: 2.0] [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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Jin X, Chen L. Fragile X syndrome as a rare disease in China - Therapeutic challenges and opportunities. Intractable Rare Dis Res 2015; 4:39-48. [PMID: 25674387 PMCID: PMC4322594 DOI: 10.5582/irdr.2014.01037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 01/14/2015] [Indexed: 12/27/2022] Open
Abstract
Recognized as the most common inherited from of intellectual disability (ID) and the most common known monogenic cause of autism spectrum disorders (ASD), Fragile X syndrome (FXS) is identified as an unmet medical need for the development of personalized medicine and targeted therapeutics for neurodevelopment disorders as a result of improved understanding of the genetic and cellular mechanisms. Consequently promising pharmacological targets have emerged from basic and translational research, are now being pursued by global pharmaceutical and biotech companies in early proof-of-concept clinical trials. With the world's largest rare disease population, China potentially has a large number of FXS patients, many of whom are under-diagnosed or even misdiagnosed, barely with any treatment. In spite of improved awareness of FXS in recent years, big gaps still exist between China and developed countries in multiple aspects. With increased public awareness, strong government support and investment, coupled with an increasingly large number of Western-trained experienced researchers engaging in new drug discovery and development, China has the potential to become an important player in the discovery of effective diagnostics and treatments for a rare disease like FXS.
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Affiliation(s)
- Xiaowei Jin
- Hua Medicine, Shanghai, China
- Address correspondence to: Dr. Xiaowei Jin, Hua Medicine, 275 Ai Di Sheng Road, Zhangjiang Hi-Tech Park, Pudong, Shanghai, China. E-mail:
| | - Li Chen
- Hua Medicine, Shanghai, China
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Vahabzadeh A, Landino SM, Finger BC, Carlezon WA, McDougle CJ. Neural targets in the study and treatment of social cognition in autism spectrum disorder. Handb Exp Pharmacol 2015; 228:309-334. [PMID: 25977088 DOI: 10.1007/978-3-319-16522-6_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The purpose of this chapter is to present results from recent research on social cognition in autism spectrum disorder (ASD). The clinical phenomenology and neuroanatomical circuitry of ASD are first briefly described. The neuropharmacology of social cognition in animal models of ASD and humans is then addressed. Next, preclinical and clinical research on the neurohormone oxytocin is reviewed. This is followed by a presentation of results from preclinical and clinical studies on the excitatory amino acid glutamate. Finally, the role of neuroinflammation in ASD is addressed from the perspectives of preclinical neuroscience and research involving humans with ASD.
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Wendling T, Ogungbenro K, Pigeolet E, Dumitras S, Woessner R, Aarons L. Model-based evaluation of the impact of formulation and food intake on the complex oral absorption of mavoglurant in healthy subjects. Pharm Res 2014; 32:1764-78. [PMID: 25425054 DOI: 10.1007/s11095-014-1574-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/10/2014] [Indexed: 11/26/2022]
Abstract
PURPOSE To compare the pharmacokinetics of intravenous (IV), oral immediate-release (IR) and oral modified-release (MR) formulations of mavoglurant in healthy subjects, and to assess the food effect on the MR formulation's input characteristics. METHODS Plasma concentration-time data from two clinical studies in healthy volunteers were pooled and analysed using NONMEM®. Drug entry into the systemic circulation was modelled using a sum of inverse Gaussian (IG) functions as an input rate function, which was estimated specifically for each formulation and food state. RESULTS Mavoglurant pharmacokinetics was best described by a two-compartment model with a sum of either two or three IG functions as input function. The mean absolute bioavailability from the MR formulation (0.387) was less than from the IR formulation (0.436). The MR formulation pharmacokinetics were significantly impacted by food: bioavailability was higher (0.508) and the input process was shorter (complete in approximately 36 versus 12 h for the fasted and fed states, respectively). CONCLUSIONS Modelling and simulation of mavoglurant pharmacokinetics indicate that the MR formulation might provide a slightly lower steady-state concentration range with lower peaks (possibly better drug tolerance) than the IR formulation, and that the MR formulation's input properties strongly depend on the food conditions at drug administration.
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Affiliation(s)
- Thierry Wendling
- Manchester Pharmacy School, The University of Manchester, Manchester, UK
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60
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de Esch CE, Zeidler S, Willemsen R. Translational endpoints in fragile X syndrome. Neurosci Biobehav Rev 2014; 46 Pt 2:256-69. [DOI: 10.1016/j.neubiorev.2013.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/07/2013] [Accepted: 10/09/2013] [Indexed: 01/01/2023]
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Kulkarni P, Saxena U. Investigational drugs for the management of Huntington's disease: are we there yet? Expert Opin Investig Drugs 2014; 23:1595-603. [PMID: 25084527 DOI: 10.1517/13543784.2014.934807] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
INTRODUCTION Huntington's disease is a hereditary neurodegenerative disease. It is designated as a rare disease in the US, which means there are < 200,000 patients in the country who suffer from it. The drugs that are currently used to treat this disease were not designed specifically for it but developed for other diseases. Presently, two classes of drugs are being developed; those that provide symptomatic relief and those that may modify course of the disease. AREAS COVERED This review is focused on seven selected drugs currently in clinical testing and describes their progress. Five of the seven drugs that are reviewed here, can be categorized as 'symptomatic' drugs, and, selisistat and PBT-2 are amongst the ones that would qualify as 'disease modifying' drugs. EXPERT OPINION The authors believe that the future treatment paradigm for this disease is best met by using a disease-modifying drug that can be administered together with symptomatic drugs. Towards that end, it is important for the industry to focus on disease-modifying drugs by targeting unique pathways and targets. Furthermore, they propose that neuroprotective drugs, that is, drugs that directly work by preserving neuronal health and function is an opportunity for such disease-modifying drugs.
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Affiliation(s)
- Pushkar Kulkarni
- University of Hyderabad Campus, Dr. Reddy's Institute of Life Sciences , Gachibowli, Hyderabad , India
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62
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Colvin SM, Kwan KY. Dysregulated nitric oxide signaling as a candidate mechanism of fragile X syndrome and other neuropsychiatric disorders. Front Genet 2014; 5:239. [PMID: 25101118 PMCID: PMC4105824 DOI: 10.3389/fgene.2014.00239] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/03/2014] [Indexed: 12/31/2022] Open
Abstract
A mechanistic understanding of the pathophysiology underpinning psychiatric disorders is essential for the development of targeted molecular therapies. For fragile X syndrome (FXS), recent mechanistic studies have been focused on the metabotropic glutamate receptor (mGluR) signaling pathway. This line of research has led to the discovery of promising candidate drugs currently undergoing various phases of clinical trial, and represents a model of how biological insights can inform therapeutic strategies in neurodevelopmental disorders. Although mGluR signaling is a key mechanism at which targeted treatments can be directed, it is likely to be one of many mechanisms contributing to FXS. A more complete understanding of the molecular and neural underpinnings of the disorder is expected to inform additional therapeutic strategies. Alterations in the assembly of neural circuits in the neocortex have been recently implicated in genetic studies of autism and schizophrenia, and may also contribute to FXS. In this review, we explore dysregulated nitric oxide signaling in the developing neocortex as a novel candidate mechanism of FXS. This possibility stems from our previous work demonstrating that neuronal nitric oxide synthase 1 (NOS1 or nNOS) is regulated by the FXS protein FMRP in the mid-fetal human neocortex. Remarkably, in the mid-late fetal and early postnatal neocortex of human FXS patients, NOS1 expression is severely diminished. Given the role of nitric oxide in diverse neural processes, including synaptic development and plasticity, the loss of NOS1 in FXS may contribute to the etiology of the disorder. Here, we outline the genetic and neurobiological data that implicate neocortical dysfunction in FXS, review the evidence supporting dysregulated nitric oxide signaling in the developing FXS neocortex and its contribution to the disorder, and discuss the implications for targeting nitric oxide signaling in the treatment of FXS and other psychiatric illnesses.
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Affiliation(s)
- Steven M Colvin
- Department of Human Genetics - The Molecular and Behavioral Neuroscience Institute, University of Michigan Medical School Ann Arbor, MI, USA
| | - Kenneth Y Kwan
- Department of Human Genetics - The Molecular and Behavioral Neuroscience Institute, University of Michigan Medical School Ann Arbor, MI, USA
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Petrov D, Pedros I, de Lemos ML, Pallàs M, Canudas AM, Lazarowski A, Beas-Zarate C, Auladell C, Folch J, Camins A. Mavoglurant as a treatment for Parkinson's disease. Expert Opin Investig Drugs 2014; 23:1165-79. [PMID: 24960254 DOI: 10.1517/13543784.2014.931370] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
INTRODUCTION A major unresolved issue in the Parkinson's disease (PD) treatment is the development of l-DOPA-induced dyskinesias (LIDs) as a side effect of chronic L-DOPA administration. Currently, LIDs are managed in part by reducing the L-DOPA dose or by the administration of amantadine. However, this treatment is only partially effective. A potential strategy, currently under investigation, is the coadministration of metabotropic glutamate receptor 5 (mGluR5) negative allosteric modulators (NAMs) and L-DOPA; a treatment that results in the improvement of dyskinesia symptoms and that permits reductions in l-DOPA dosage frequency. AREAS COVERED The authors examine the role of mGluR5 in the pathophysiology of PD and the potential use of mGluR5 NAM as an adjuvant therapy together with a primary treatment with L-DOPA. Specifically, the authors look at the mavoglurant therapy and the evidence presented through preclinical and clinical trials. EXPERT OPINION Interaction between mGluR5 NAM and L-DOPA is an area of interest in PD research as concomitant treatment results in the improvement of LID symptoms in humans, thus enhancing the patient's quality of life. However, few months ago, Novartis decided to discontinue clinical trials of mavoglurant for the treatment of LID, due to the lack of efficacy demonstrated in trials NCT01385592 and NCT01491529, although no safety concerns were involved in this decision. Nevertheless, the potential application of mGluR5 antagonists as neuroprotective agents must be considered and further studies are warranted to better investigate their potential.
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Affiliation(s)
- Dmitry Petrov
- Universitat de Barcelona, Institut de Biomedicina (IBUB), Centros de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Unitat de Farmacologia I Farmacognòsia, Facultat de Farmàcia , Barcelona, Avda/Joan XXIII , Spain
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Fragile X syndrome: a preclinical review on metabotropic glutamate receptor 5 (mGluR5) antagonists and drug development. Psychopharmacology (Berl) 2014; 231:1217-26. [PMID: 24232444 DOI: 10.1007/s00213-013-3330-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Fragile X syndrome (FXS) is considered the leading inherited cause of intellectual disability and autism. In FXS, the fragile X mental retardation 1 (FMR1) gene is silenced and the fragile X mental retardation protein (FMRP) is not expressed, resulting in the characteristic features of the syndrome. Despite recent advances in understanding the pathophysiology of FXS, there is still no cure for this condition; current treatment is symptomatic. Preclinical research is essential in the development of potential therapeutic agents. OBJECTIVES This review provides an overview of the preclinical evidence supporting metabotropic glutamate receptor 5 (mGluR5) antagonists as therapeutic agents for FXS. RESULTS According to the mGluR theory of FXS, the absence of FMRP leads to enhanced glutamatergic signaling via mGluR5, which leads to increased protein synthesis and defects in synaptic plasticity including enhanced long-term depression. As such, efforts to develop agents that target the underlying pathophysiology of FXS have focused on mGluR5 modulation. Animal models, particularly the Fmr1 knockout mouse model, have become invaluable in exploring therapeutic approaches on an electrophysiological, behavioral, biochemical, and neuroanatomical level. Two direct approaches are currently being investigated for FXS treatment: reactivating the FMR1 gene and compensating for the lack of FMRP. The latter approach has yielded promising results, with mGluR5 antagonists showing efficacy in clinical trials. CONCLUSIONS Targeting mGluR5 is a valid approach for the development of therapeutic agents that target the underlying pathophysiology of FXS. Several compounds are currently in development, with encouraging results.
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Uzunova G, Hollander E, Shepherd J. The role of ionotropic glutamate receptors in childhood neurodevelopmental disorders: autism spectrum disorders and fragile x syndrome. Curr Neuropharmacol 2014; 12:71-98. [PMID: 24533017 PMCID: PMC3915351 DOI: 10.2174/1570159x113116660046] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/20/2013] [Accepted: 09/25/2013] [Indexed: 12/20/2022] Open
Abstract
Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are relatively common childhood neurodevelopmental disorders with increasing incidence in recent years. They are currently accepted as disorders of the synapse with alterations in different forms of synaptic communication and neuronal network connectivity. The major excitatory neurotransmitter system in brain, the glutamatergic system, is implicated in learning and memory, synaptic plasticity, neuronal development. While much attention is attributed to the role of metabotropic glutamate receptors in ASD and FXS, studies indicate that the ionotropic glutamate receptors (iGluRs) and their regulatory proteins are also altered in several brain regions. Role of iGluRs in the neurobiology of ASD and FXS is supported by a weight of evidence that ranges from human genetics to in vitro cultured neurons. In this review we will discuss clinical, molecular, cellular and functional changes in NMDA, AMPA and kainate receptors and the synaptic proteins that regulate them in the context of ASD and FXS. We will also discuss the significance for the development of translational biomarkers and treatments for the core symptoms of ASD and FXS.
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Affiliation(s)
- Genoveva Uzunova
- Autism and Obsessive Compulsive Spectrum Program, Department of Psychiatry, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th St, Bronx, New York 10467-2490
| | - Eric Hollander
- Autism and Obsessive Compulsive Spectrum Program, Department of Psychiatry, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th St, Bronx, New York 10467-2490
| | - Jason Shepherd
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, 531A Wintrobe, 20N 1900 E, Salt Lake City, Utah 84132
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Braat S, Kooy RF. Fragile X syndrome neurobiology translates into rational therapy. Drug Discov Today 2014; 19:510-9. [PMID: 24508819 DOI: 10.1016/j.drudis.2014.01.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/19/2014] [Accepted: 01/27/2014] [Indexed: 12/29/2022]
Abstract
Causal genetic defects have been identified for various neurodevelopmental disorders. A key example in this respect is fragile X syndrome, one of the most frequent genetic causes of intellectual disability and autism. Since the discovery of the causal gene, insights into the underlying pathophysiological mechanisms have increased exponentially. Over the past years, defects were discovered in pathways that are potentially amendable by pharmacological treatment. These findings have inspired the initiation of clinical trials in patients. The targeted pathways converge in part with those of related neurodevelopmental disorders raising hopes that the treatments developed for this specific disorder might be more broadly applicable.
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Affiliation(s)
- Sien Braat
- Department of Medical Genetics, University of Antwerp, Prins Boudewijnlaan 43, Antwerp, Belgium
| | - R Frank Kooy
- Department of Medical Genetics, University of Antwerp, Prins Boudewijnlaan 43, Antwerp, Belgium.
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67
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Doll CA, Broadie K. Impaired activity-dependent neural circuit assembly and refinement in autism spectrum disorder genetic models. Front Cell Neurosci 2014; 8:30. [PMID: 24570656 PMCID: PMC3916725 DOI: 10.3389/fncel.2014.00030] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 01/21/2014] [Indexed: 01/23/2023] Open
Abstract
Early-use activity during circuit-specific critical periods refines brain circuitry by the coupled processes of eliminating inappropriate synapses and strengthening maintained synapses. We theorize these activity-dependent (A-D) developmental processes are specifically impaired in autism spectrum disorders (ASDs). ASD genetic models in both mouse and Drosophila have pioneered our insights into normal A-D neural circuit assembly and consolidation, and how these developmental mechanisms go awry in specific genetic conditions. The monogenic fragile X syndrome (FXS), a common cause of heritable ASD and intellectual disability, has been particularly well linked to defects in A-D critical period processes. The fragile X mental retardation protein (FMRP) is positively activity-regulated in expression and function, in turn regulates excitability and activity in a negative feedback loop, and appears to be required for the A-D remodeling of synaptic connectivity during early-use critical periods. The Drosophila FXS model has been shown to functionally conserve the roles of human FMRP in synaptogenesis, and has been centrally important in generating our current mechanistic understanding of the FXS disease state. Recent advances in Drosophila optogenetics, transgenic calcium reporters, highly-targeted transgenic drivers for individually-identified neurons, and a vastly improved connectome of the brain are now being combined to provide unparalleled opportunities to both manipulate and monitor A-D processes during critical period brain development in defined neural circuits. The field is now poised to exploit this new Drosophila transgenic toolbox for the systematic dissection of A-D mechanisms in normal versus ASD brain development, particularly utilizing the well-established Drosophila FXS disease model.
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Affiliation(s)
- Caleb A Doll
- Department of Biological Sciences, Vanderbilt University Nashville, TN, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University Nashville, TN, USA ; Kennedy Center for Research on Human Development, Vanderbilt University Nashville, TN, USA
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Sethna F, Moon C, Wang H. From FMRP function to potential therapies for fragile X syndrome. Neurochem Res 2013; 39:1016-31. [PMID: 24346713 DOI: 10.1007/s11064-013-1229-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 12/03/2013] [Accepted: 12/12/2013] [Indexed: 12/12/2022]
Abstract
Fragile X syndrome (FXS) is caused by mutations in the fragile X mental retardation 1 (FMR1) gene. Most FXS cases occur due to the expansion of the CGG trinucleotide repeats in the 5' un-translated region of FMR1, which leads to hypermethylation and in turn silences the expression of FMRP (fragile X mental retardation protein). Numerous studies have demonstrated that FMRP interacts with both coding and non-coding RNAs and represses protein synthesis at dendritic and synaptic locations. In the absence of FMRP, the basal protein translation is enhanced and not responsive to neuronal stimulation. The altered protein translation may contribute to functional abnormalities in certain aspects of synaptic plasticity and intracellular signaling triggered by Gq-coupled receptors. This review focuses on the current understanding of FMRP function and potential therapeutic strategies that are mainly based on the manipulation of FMRP targets and knowledge gained from FXS pathophysiology.
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Affiliation(s)
- Ferzin Sethna
- Genetics Program, Michigan State University, East Lansing, MI, 48824, USA
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69
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The promising trajectory of autism therapeutics discovery. Drug Discov Today 2013; 19:838-44. [PMID: 24362109 DOI: 10.1016/j.drudis.2013.12.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 11/04/2013] [Accepted: 12/11/2013] [Indexed: 11/24/2022]
Abstract
Pharmacological interventions for neurodevelopmental disorders are increasingly tractable. Autism is a neurodevelopmental disorder that affects approximately 1% of the population. Currently, the standard of care is early behavioral therapy. No approved medical treatments for the diagnostic symptoms are available. Strong evidence for genetic causes of autism implicates proteins that mediate synaptic transmission and structure. Mouse models with targeted mutations in these synaptic genes display behavioral symptoms relevant to the social communication abnormalities and repetitive behaviors that define autism spectrum disorder (ASD), along with biological abnormalities in synaptic physiology and morphology. As we discuss here, promising pharmacological targets, emerging from the mouse model studies, are now being pursued in early clinical trials. Thus, a high-prevalence disorder that was previously considered to be medically untreatable is now moving into the therapeutic arena.
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Gomez-Mancilla B, Berry-Kravis E, Hagerman R, von Raison F, Apostol G, Ufer M, Gasparini F, Jacquemont S. Development of mavoglurant and its potential for the treatment of fragile X syndrome. Expert Opin Investig Drugs 2013; 23:125-34. [PMID: 24251408 DOI: 10.1517/13543784.2014.857400] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. With no curative treatment available, current therapeutic approaches are aimed at symptom management. FXS is caused by silencing the FMR1 gene, which encodes FMRP; as loss of FMRP leads to the development of symptoms associated with FXS. AREAS COVERED In this evaluation, the authors examine the role of the metabotropic glutamate receptor 5 (mGluR5) in the pathophysiology of FXS, and its suitability as a target for rescuing the disease state. Furthermore, the authors review the evidence from preclinical studies of pharmacological interventions targeting mGluR5 in FXS. Lastly, the authors assess the findings from clinical studies in FXS, in particular the use of the Aberrant Behavior Checklist-Community Edition (ABC-C) and the recently developed ABC-C for FXS scale, as clinical endpoints to assess disease modification in this patient population. EXPERT OPINION There is cautious optimism for the successful treatment of the core behavioral and cognitive symptoms of FXS based on preclinical data in animal models and early studies in humans. However, the association between mGluR5-heightened responsiveness and the clinical phenotype in humans remains to be demonstrated. Many questions regarding the optimal treatment and outcome measures of FXS remain unanswered.
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Affiliation(s)
- Baltazar Gomez-Mancilla
- Novartis Institutes for BioMedical Research Basel, Forum 1 , Novartis Campus, CH-4056 Basel , Switzerland +41 61 324 0164 ; +41 61 324 8913 ;
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Metabotropic glutamate receptor 5-negative allosteric modulators for the treatment of psychiatric and neurological disorders (2009–July 2013). Pharm Pat Anal 2013; 2:767-802. [DOI: 10.4155/ppa.13.58] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Negative allosteric modulators of metabotropic glutamate receptor 5 (mGlu5) have been actively pursued for over a decade as a potential treatment for anxiety, depression, substance abuse, pain, levodopa-induced dyskinesia in Parkinson’s disease, fragile X Syndrome, autism, gastroesophageal reflux disease and lower-urinary-tract disorders. This article begins with an introduction of preclinical validation of potential therapies for psychiatric and neurological disorders, and of clinical results, followed by a comprehensive overview of the mGlu5-negative allosteric modulator patent applications published between 2009 and July 2013, with a focus on the analysis of structure and in silico CNS drug-like properties of example compounds and disclosed data. Given positive results in proof-of-concept studies in humans for certain indications such as levodopa-induced dyskinesia in Parkinson’s disease, fragile X Syndrome, gastroesophageal reflux disease, migraine and anxiety, and the soaring chemical diversity among the mGlu5-negative allosteric modulators, there is reason to believe that a drug will emerge from this therapeutic class in the near future.
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Bagni C, Oostra BA. Fragile X syndrome: From protein function to therapy. Am J Med Genet A 2013; 161A:2809-21. [PMID: 24115651 DOI: 10.1002/ajmg.a.36241] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/28/2013] [Indexed: 12/23/2022]
Abstract
Fragile X syndrome (FXS) is the leading monogenic cause of intellectual disability and autism. The FMR1 gene contains a CGG repeat present in the 5'-untranslated region which can be unstable upon transmission to the next generation. The repeat is up to 55 CGGs long in the normal population. In patients with fragile X syndrome (FXS), a repeat length exceeding 200 CGGs generally leads to methylation of the repeat and the promoter region, which is accompanied by silencing of the FMR1 gene. The disease is a result of lack of expression of the fragile X mental retardation protein leading to severe symptoms, including intellectual disability, hyperactivity, and autistic-like behavior. The FMR1 protein (FMRP) has a number of functions. The translational dysregulation of a subset of mRNAs targeted by FMRP is probably the major contribution to FXS. FMRP is also involved in mRNA transport to synapses where protein synthesis occurs. For some FMRP-bound mRNAs, FMRP is a direct modulator of mRNA stability either by sustaining or preventing mRNA decay. Increased knowledge about the role of FMRP has led to the identification of potential treatments for fragile X syndrome that were often tested first in the different animal models. This review gives an overview about the present knowledge of the function of FMRP and the therapeutic strategies in mouse and man.
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Affiliation(s)
- Claudia Bagni
- VIB Center for the Biology of Disease, Catholic University of Leuven, Leuven, Belgium; Department of Biomedicine and Prevention, University of Rome, Tor Vergata, Italy
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Sourial M, Cheng C, Doering LC. Progress toward therapeutic potential for AFQ056 in Fragile X syndrome. J Exp Pharmacol 2013; 5:45-54. [PMID: 27186135 PMCID: PMC4863540 DOI: 10.2147/jep.s27044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and the leading single-gene cause of autism. It is caused by the lack of production of the Fragile X mental retardation protein (FMRP), resulting in cognitive deficits, hyperactivity, and autistic behaviors. Breakthrough advances in potential therapy for FXS followed the discovery that aberrant group 1 metabotropic glutamate receptor (mGluR) signaling is an important constituent of the pathophysiology of the syndrome. Research has indicated that upon neuronal stimulation, FMRP acts downstream of group 1 mGluRs (mGluRs1/5) to inhibit protein synthesis, long-term depression, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor internalization. To offset the deficits caused by the lack of FMRP, many pharmaceutical companies have designed medicinal drugs to target the unrestrained stimulation of mGluR5 signaling in FXS. Indeed, promising results from animal and clinical studies suggest that mGluR5 antagonists such as AFQ056 can successfully correct many of the deficits in FXS. In this review, we cover the animal studies performed to date that test the role of AFQ056 as a selective mGluR5 antagonist to alleviate the phenotypes of FXS.
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Affiliation(s)
- Mary Sourial
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Connie Cheng
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Laurie C Doering
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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