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MeCP2 and transcriptional control of eukaryotic gene expression. Eur J Cell Biol 2022; 101:151237. [DOI: 10.1016/j.ejcb.2022.151237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/30/2022] [Accepted: 05/09/2022] [Indexed: 11/19/2022] Open
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Mapelli L, Soda T, D’Angelo E, Prestori F. The Cerebellar Involvement in Autism Spectrum Disorders: From the Social Brain to Mouse Models. Int J Mol Sci 2022; 23:ijms23073894. [PMID: 35409253 PMCID: PMC8998980 DOI: 10.3390/ijms23073894] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 02/04/2023] Open
Abstract
Autism spectrum disorders (ASD) are pervasive neurodevelopmental disorders that include a variety of forms and clinical phenotypes. This heterogeneity complicates the clinical and experimental approaches to ASD etiology and pathophysiology. To date, a unifying theory of these diseases is still missing. Nevertheless, the intense work of researchers and clinicians in the last decades has identified some ASD hallmarks and the primary brain areas involved. Not surprisingly, the areas that are part of the so-called “social brain”, and those strictly connected to them, were found to be crucial, such as the prefrontal cortex, amygdala, hippocampus, limbic system, and dopaminergic pathways. With the recent acknowledgment of the cerebellar contribution to cognitive functions and the social brain, its involvement in ASD has become unmistakable, though its extent is still to be elucidated. In most cases, significant advances were made possible by recent technological developments in structural/functional assessment of the human brain and by using mouse models of ASD. Mouse models are an invaluable tool to get insights into the molecular and cellular counterparts of the disease, acting on the specific genetic background generating ASD-like phenotype. Given the multifaceted nature of ASD and related studies, it is often difficult to navigate the literature and limit the huge content to specific questions. This review fulfills the need for an organized, clear, and state-of-the-art perspective on cerebellar involvement in ASD, from its connections to the social brain areas (which are the primary sites of ASD impairments) to the use of monogenic mouse models.
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Affiliation(s)
- Lisa Mapelli
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (T.S.); (E.D.)
- Correspondence: (L.M.); (F.P.)
| | - Teresa Soda
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (T.S.); (E.D.)
| | - Egidio D’Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (T.S.); (E.D.)
- Brain Connectivity Center, IRCCS Mondino Foundation, 27100 Pavia, Italy
| | - Francesca Prestori
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy; (T.S.); (E.D.)
- Correspondence: (L.M.); (F.P.)
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Bach S, Shovlin S, Moriarty M, Bardoni B, Tropea D. Rett Syndrome and Fragile X Syndrome: Different Etiology With Common Molecular Dysfunctions. Front Cell Neurosci 2021; 15:764761. [PMID: 34867203 PMCID: PMC8640214 DOI: 10.3389/fncel.2021.764761] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/27/2021] [Indexed: 01/04/2023] Open
Abstract
Rett syndrome (RTT) and Fragile X syndrome (FXS) are two monogenetic neurodevelopmental disorders with complex clinical presentations. RTT is caused by mutations in the Methyl-CpG binding protein 2 gene (MECP2) altering the function of its protein product MeCP2. MeCP2 modulates gene expression by binding methylated CpG dinucleotides, and by interacting with transcription factors. FXS is caused by the silencing of the FMR1 gene encoding the Fragile X Mental Retardation Protein (FMRP), a RNA binding protein involved in multiple steps of RNA metabolism, and modulating the translation of thousands of proteins including a large set of synaptic proteins. Despite differences in genetic etiology, there are overlapping features in RTT and FXS, possibly due to interactions between MeCP2 and FMRP, and to the regulation of pathways resulting in dysregulation of common molecular signaling. Furthermore, basic physiological mechanisms are regulated by these proteins and might concur to the pathophysiology of both syndromes. Considering that RTT and FXS are disorders affecting brain development, and that most of the common targets of MeCP2 and FMRP are involved in brain activity, we discuss the mechanisms of synaptic function and plasticity altered in RTT and FXS, and we consider the similarities and the differences between these two disorders.
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Affiliation(s)
- Snow Bach
- School of Mathematical Sciences, Dublin City University, Dublin, Ireland.,Neuropsychiatric Genetics, Department of Psychiatry, School of Medicine, Trinity College Dublin, Trinity Translational Medicine Institute, St James's Hospital, Dublin, Ireland
| | - Stephen Shovlin
- Neuropsychiatric Genetics, Department of Psychiatry, School of Medicine, Trinity College Dublin, Trinity Translational Medicine Institute, St James's Hospital, Dublin, Ireland
| | | | - Barbara Bardoni
- Inserm, CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Université Côte d'Azur, Valbonne, France
| | - Daniela Tropea
- Neuropsychiatric Genetics, Department of Psychiatry, School of Medicine, Trinity College Dublin, Trinity Translational Medicine Institute, St James's Hospital, Dublin, Ireland.,Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.,FutureNeuro, The SFI Research Centre for Chronic and Rare Neurological Diseases, Dublin, Ireland
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4
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Kim HJ, Bayarsaikhan D, Lee J, Bayarsaikhan G, Lee B. Brain-Derived Neurotrophic Factor Secreting Human Mesenchymal Stem Cells Improve Outcomes in Rett Syndrome Mouse Models. Front Neurosci 2021; 15:725398. [PMID: 34690674 PMCID: PMC8526791 DOI: 10.3389/fnins.2021.725398] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 09/01/2021] [Indexed: 11/13/2022] Open
Abstract
Rett syndrome (RTT) is a severe X-linked dominant neurodevelopmental disorder caused by mutations in the methyl-CpG-binding protein 2 (MECP2) gene; MeCP2 regulates the expression of brain-derived neurotrophic factor (BDNF) and increasing BDNF levels ameliorates RTT symptoms. However, the clinical application of BDNF is limited, because of its short half-life and low penetrance across the blood-brain barrier. In this study, we generated BDNF-secreting mesenchymal stem cells (MSCs) from the human umbilical cord cells, using CRISPR-Cas9. We studied the effects of BDNF-MSCs in MECP2 knockout and MECP2-deficient mice. BDNF-MSCs upregulated the expression of BDNF, pAKT, and pERK1/2 and downregulated that of pp38, both in vitro and in vivo. In our in vivo experiments, BDNF-MSCs increased the body and brain weights in mice. BDNF-MSCs increased the neuronal cell numbers in the hippocampus, cortex, and striatum; in addition, they increased the number of synapses. BDNF-MSCs upregulated BDNF and the activity of BDNF downstream effectors, such as pAKT and pERK 1/2; this upregulation was persistent. In conclusion, BDNF-MSCs generated using CRISPR-Cas9 could be a therapeutic strategy for treating RTT.
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Affiliation(s)
- Hyo Jeong Kim
- Department of Anatomy & Cell Biology, Gachon University College of Medicine, Incheon, South Korea.,Department of Pediatrics, Gil Medical Center, Gachon University College of Medicine, Incheon, South Korea
| | - Delger Bayarsaikhan
- Center for Genomics and Proteomics and Stem Cell Core Facility, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea
| | - Jaesuk Lee
- Center for Genomics and Proteomics and Stem Cell Core Facility, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea.,Department of Chemistry, College of Natural Science, Seoul National University, Seoul, South Korea
| | - Govigerel Bayarsaikhan
- Center for Genomics and Proteomics and Stem Cell Core Facility, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea
| | - Bonghee Lee
- Department of Anatomy & Cell Biology, Gachon University College of Medicine, Incheon, South Korea.,Center for Genomics and Proteomics and Stem Cell Core Facility, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, South Korea
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5
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Pejhan S, Rastegar M. Role of DNA Methyl-CpG-Binding Protein MeCP2 in Rett Syndrome Pathobiology and Mechanism of Disease. Biomolecules 2021; 11:75. [PMID: 33429932 PMCID: PMC7827577 DOI: 10.3390/biom11010075] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/01/2021] [Accepted: 01/03/2021] [Indexed: 12/16/2022] Open
Abstract
Rett Syndrome (RTT) is a severe, rare, and progressive developmental disorder with patients displaying neurological regression and autism spectrum features. The affected individuals are primarily young females, and more than 95% of patients carry de novo mutation(s) in the Methyl-CpG-Binding Protein 2 (MECP2) gene. While the majority of RTT patients have MECP2 mutations (classical RTT), a small fraction of the patients (atypical RTT) may carry genetic mutations in other genes such as the cyclin-dependent kinase-like 5 (CDKL5) and FOXG1. Due to the neurological basis of RTT symptoms, MeCP2 function was originally studied in nerve cells (neurons). However, later research highlighted its importance in other cell types of the brain including glia. In this regard, scientists benefitted from modeling the disease using many different cellular systems and transgenic mice with loss- or gain-of-function mutations. Additionally, limited research in human postmortem brain tissues provided invaluable findings in RTT pathobiology and disease mechanism. MeCP2 expression in the brain is tightly regulated, and its altered expression leads to abnormal brain function, implicating MeCP2 in some cases of autism spectrum disorders. In certain disease conditions, MeCP2 homeostasis control is impaired, the regulation of which in rodents involves a regulatory microRNA (miR132) and brain-derived neurotrophic factor (BDNF). Here, we will provide an overview of recent advances in understanding the underlying mechanism of disease in RTT and the associated genetic mutations in the MECP2 gene along with the pathobiology of the disease, the role of the two most studied protein variants (MeCP2E1 and MeCP2E2 isoforms), and the regulatory mechanisms that control MeCP2 homeostasis network in the brain, including BDNF and miR132.
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Affiliation(s)
| | - Mojgan Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada;
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Miranda-Lourenço C, Ribeiro-Rodrigues L, Fonseca-Gomes J, Tanqueiro SR, Belo RF, Ferreira CB, Rei N, Ferreira-Manso M, de Almeida-Borlido C, Costa-Coelho T, Freitas CF, Zavalko S, Mouro FM, Sebastião AM, Xapelli S, Rodrigues TM, Diógenes MJ. Challenges of BDNF-based therapies: From common to rare diseases. Pharmacol Res 2020; 162:105281. [PMID: 33161136 DOI: 10.1016/j.phrs.2020.105281] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 12/11/2022]
Abstract
Neurotrophins are a well-known family of neurotrophic factors that play an important role both in the central and peripheral nervous systems, where they modulate neuronal survival, development, function and plasticity. Brain-derived neurotrophic factor (BDNF) possesses diverse biological functions which are mediated by the activation of two main classes of receptors, the tropomyosin-related kinase (Trk) B and the p75 neurotrophin receptor (p75NTR). The therapeutic potential of BDNF has drawn attention since dysregulation of its signalling cascades has been suggested to underlie the pathogenesis of both common and rare diseases. Multiple strategies targeting this neurotrophin have been tested; most have found obstacles that ultimately hampered their effectiveness. This review focuses on the involvement of BDNF and its receptors in the pathophysiology of Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis (ALS) and Rett Syndrome (RTT). We describe the known mechanisms leading to the impairment of BDNF/TrkB signalling in these disorders. Such mechanistic insight highlights how BDNF signalling compromise can take various shapes, nearly disease-specific. Therefore, BDNF-based therapeutic strategies must be specifically tailored and are more likely to succeed if a combination of resources is employed.
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Affiliation(s)
- Catarina Miranda-Lourenço
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Leonor Ribeiro-Rodrigues
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - João Fonseca-Gomes
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Sara R Tanqueiro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Rita F Belo
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Catarina B Ferreira
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Nádia Rei
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Mafalda Ferreira-Manso
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Carolina de Almeida-Borlido
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Tiago Costa-Coelho
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Céline Felicidade Freitas
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Svitlana Zavalko
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Francisco M Mouro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Sara Xapelli
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Tiago M Rodrigues
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Institute of Molecular and Clinical Ophthalmology Basel (IOB), Mittlere Strasse 91, 4031 Basel, Switzerland
| | - Maria J Diógenes
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, 1649-028 Lisboa, Portugal.
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7
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Miranda-Lourenço C, Duarte ST, Palminha C, Gaspar C, Rodrigues TM, Magalhães-Cardoso T, Rei N, Colino-Oliveira M, Gomes R, Ferreira S, Rosa J, Xapelli S, Armstrong J, García-Cazorla À, Correia-de-Sá P, Sebastião AM, Diógenes MJ. Impairment of adenosinergic system in Rett syndrome: Novel therapeutic target to boost BDNF signalling. Neurobiol Dis 2020; 145:105043. [PMID: 32798727 DOI: 10.1016/j.nbd.2020.105043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/23/2020] [Accepted: 08/08/2020] [Indexed: 01/20/2023] Open
Abstract
Rett syndrome (RTT; OMIM#312750) is mainly caused by mutations in the X-linked MECP2 gene (methyl-CpG-binding protein 2 gene; OMIM*300005), which leads to impairments in the brain-derived neurotrophic factor (BDNF) signalling. The boost of BDNF mediated effects would be a significant breakthrough but it has been hampered by the difficulty to administer BDNF to the central nervous system. Adenosine, an endogenous neuromodulator, may accomplish that role since through A2AR it potentiates BDNF synaptic actions in healthy animals. We thus characterized several hallmarks of the adenosinergic and BDNF signalling in RTT and explored whether A2AR activation could boost BDNF actions. For this study, the RTT animal model, the Mecp2 knockout (Mecp2-/y) (B6.129P2 (C)-Mecp2tm1.1Bird/J) mouse was used. Whenever possible, parallel data was also obtained from post-mortem brain samples from one RTT patient. Ex vivo extracellular recordings of field excitatory post-synaptic potentials in CA1 hippocampal area were performed to evaluate synaptic transmission and long-term potentiation (LTP). RT-PCR was used to assess mRNA levels and Western Blot or radioligand binding assays were performed to evaluate protein levels. Changes in cortical and hippocampal adenosine content were assessed by liquid chromatography with diode array detection (LC/DAD). Hippocampal ex vivo experiments revealed that the facilitatory actions of BDNF upon LTP is absent in Mecp2-/y mice and that TrkB full-length (TrkB-FL) receptor levels are significantly decreased. Extracts of the hippocampus and cortex of Mecp2-/y mice revealed less adenosine amount as well as less A2AR protein levels when compared to WT littermates, which may partially explain the deficits in adenosinergic tonus in these animals. Remarkably, the lack of BDNF effect on hippocampal LTP in Mecp2-/y mice was overcome by selective activation of A2AR with CGS21680. Overall, in Mecp2-/y mice there is an impairment on adenosinergic system and BDNF signalling. These findings set the stage for adenosine-based pharmacological therapeutic strategies for RTT, highlighting A2AR as a therapeutic target in this devastating pathology.
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Affiliation(s)
- Catarina Miranda-Lourenço
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Sofia T Duarte
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal; Child Neurology Department, Hospital Dona Estefânia - Centro Hospitalar Universitário de Lisboa Central, Portugal.
| | - Cátia Palminha
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Cláudia Gaspar
- Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Tiago M Rodrigues
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal; Institute of Molecular and Clinical Ophtalmology, Mittlere Strasse 91, CH-4031 Basel, Switzerland.
| | - Teresa Magalhães-Cardoso
- Laboratório de Farmacologia e Neurobiologia / MedInUP, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP), Porto, Portugal.
| | - Nádia Rei
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Mariana Colino-Oliveira
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Rui Gomes
- Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Sara Ferreira
- Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Jéssica Rosa
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Sara Xapelli
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Judith Armstrong
- Genetics Department, Hospital Sant Joan de Deu. Institut Pediàtric de Recerca and CIBERER. (ISCIII), Barcelona, Spain.
| | - Àngels García-Cazorla
- Synaptic Metabolism Laboratory, Neurology Department; Institut Pediàtric de Recerca and CIBERER. (ISCIII), Barcelona, Spain.
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia / MedInUP, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP), Porto, Portugal.
| | - Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
| | - Maria José Diógenes
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina e Instituto de Medicina Molecular - João Lobo Antunes, Universidade de Lisboa, Lisboa, Portugal.
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8
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Pejhan S, Siu VM, Ang LC, Del Bigio MR, Rastegar M. Differential brain region-specific expression of MeCP2 and BDNF in Rett Syndrome patients: a distinct grey-white matter variation. Neuropathol Appl Neurobiol 2020; 46:735-750. [PMID: 32246495 DOI: 10.1111/nan.12619] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 01/03/2020] [Accepted: 03/23/2020] [Indexed: 12/18/2022]
Abstract
INTRODUCTION AND OBJECTIVES Rett Syndrome (RTT) is a neurodevelopmental disorder caused by Methyl CpG Binding Protein 2 (MECP2) gene mutations. Previous studies of MeCP2 in the human brain showed variable and inconsistent mosaic-pattern immunolabelling, which has been interpreted as a reflection of activation-state variability. We aimed to study post mortem MeCP2 and BDNF (MeCP2 target) degradation and brain region-specific detection in relation to RTT pathophysiology. METHODS We investigated MeCP2 and BDNF stabilities in non-RTT human brains by immunohistochemical labelling and compared them in three brain regions of RTT and controls. RESULTS In surgically excised samples of human hippocampus and cerebellum, MeCP2 was universally detected. There was no significantly obvious difference between males and females. However, post mortem delay in autopsy samples had substantial influence on MeCP2 detection. Immunohistochemistry studies in RTT patients showed lower MeCP2 detection in glial cells of the white matter. Glial fibrillary acidic protein (GFAP) expression was also reduced in RTT brain samples without obvious change in myelin basic protein (MBP). Neurons did not show any noticeable decrease in MeCP2 detection. BDNF immunohistochemical detection showed an astroglial/endothelial pattern without noticeable difference between RTT and controls. CONCLUSIONS Our findings indicate that MeCP2 protein is widely expressed in mature human brain cells at all ages. However, our data points towards a possible white matter abnormality in RTT and highlights the importance of studying human RTT brain tissues in parallel with research on animal and cell models of RTT.
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Affiliation(s)
- S Pejhan
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - V M Siu
- Division of Medical Genetics, Department of Paediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - L C Ang
- Department of Pathology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - M R Del Bigio
- Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - M Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
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Karayağmurlu A, Dursun OB, Esin İS, Coşkun M. Serum NGF levels may be associated with intrauterine antiepileptic exposure-related developmental problems. Epilepsy Behav 2019; 97:60-66. [PMID: 31181430 DOI: 10.1016/j.yebeh.2019.05.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/03/2019] [Accepted: 05/08/2019] [Indexed: 01/16/2023]
Abstract
OBJECTIVE It has been shown that maternal epilepsy and antiepileptic drug use during pregnancy have adverse developmental outcomes in children. The aim of this study was to investigate the developmental outcomes of maternal epilepsy and prenatal antiepileptic exposure. We also looked for the associations between serum levels of glial cell-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) and developmental outcomes. METHODS This is a retrospective, nonrandomized, case-controlled study. Fifty-three children aged two to six years old with maternal epilepsy were included in the case group. Fifty-three age- and gender-matched children without maternal epilepsy were included in the control group. Developmental assessment was conducted using the Denver II Developmental Screening Test (DDST-II). Serum levels of NGF and GDNF were measured using an enzyme-linked immunosorbent assay (ELISA) kit. RESULTS Multiple regression analysis revealed that prenatal antiepileptic exposure was significantly associated with lower global developmental scores (B = -7.5, confidence interval (CI): -13.1; -1.9, p = 0.009) while periconceptional folate use was associated with a reduced risk for adverse developmental outcomes (B = 6.6, CI: 0.91; 12.3, p = 0.024). Children with prenatal antiepileptic exposure are at increased risk for global developmental delay (GDD) particularly for language domain (p = 0.018). We found a statistically significant positive correlation between NGF levels and global developmental scores (r = 0.302, p = 0.009). Serum levels of GDNF in children with maternal epilepsy were significantly lower than the children without maternal epilepsy (p = 0.025). CONCLUSIONS Prenatal antiepileptic exposure was related with the increased risk of GDD while periconceptional folate use was related with lower risk. Clinicians should inform all women in reproductive age with epilepsy about the possible benefits and risks of antiepileptic drug use during a possible pregnancy. Periconceptional folate use has protective effect on child development, and all women on antiepileptic drugs should be encouraged for periconceptional folate use. Serum NGF levels may be a promising biomarker for monitoring global development delay in at-risk population.
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Affiliation(s)
- Ali Karayağmurlu
- Department of Child and Adolescent Psychiatry, Faculty of Medicine, Istanbul University, İstanbul, Turkey.
| | - Onur Burak Dursun
- Department of Child and Adolescent Psychiatry, University of Health Sciences, International School of Medicine, Istanbul, Turkey
| | - İbrahim Selçuk Esin
- Department of Child and Adolescent Psychiatry, Faculty of Medicine, Atatürk University, Erzurum, Turkey
| | - Murat Coşkun
- Department of Child and Adolescent Psychiatry, Faculty of Medicine, Istanbul University, İstanbul, Turkey
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Byiers B, Barney C, Ehrhardt M, Panoskaltsis-Mortari A, Feyma T, Beisang A, Symons FJ. Initial Observations of Salivary Brain-Derived Neurotrophic Factor Levels in Rett Syndrome. Pediatr Neurol 2018; 80:88-89. [PMID: 29373156 PMCID: PMC5857231 DOI: 10.1016/j.pediatrneurol.2017.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/07/2017] [Accepted: 11/10/2017] [Indexed: 10/18/2022]
Affiliation(s)
- Breanne Byiers
- Department of Educational Psychology, University of Minnesota, Minneapolis, Minnesota.
| | - Chantel Barney
- Gillette Children’s Specialty Healthcare, Saint Paul, MN 55101
| | | | | | - Timothy Feyma
- Gillette Children’s Specialty Healthcare, Saint Paul, MN 55101
| | - Arthur Beisang
- Gillette Children’s Specialty Healthcare, Saint Paul, MN 55101
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11
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Scavenging reactive oxygen species inhibits status epilepticus-induced neuroinflammation. Exp Neurol 2017; 298:13-22. [PMID: 28822838 DOI: 10.1016/j.expneurol.2017.08.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/26/2017] [Accepted: 08/15/2017] [Indexed: 02/07/2023]
Abstract
Inflammation has been identified as an important mediator of seizures and epileptogenesis. Understanding the mechanisms underlying seizure-induced neuroinflammation could lead to the development of novel therapies for the epilepsies. Reactive oxygen species (ROS) are recognized as mediators of seizure-induced neuronal damage and are known to increase in models of epilepsies. ROS are also known to contribute to inflammation in several disease states. We hypothesized that ROS are key modulators of neuroinflammation i.e. pro-inflammatory cytokine production and microglial activation in acquired epilepsy. The role of ROS in modulating seizure-induced neuroinflammation was investigated in the pilocarpine model of temporal lobe epilepsy (TLE). Pilocarpine-induced status epilepticus (SE) resulted in a time-dependent increase in pro-inflammatory cytokine production in the hippocampus and piriform cortex. Scavenging ROS with a small-molecule catalytic antioxidant decreased SE-induced pro-inflammatory cytokine production and microglial activation, suggesting that ROS contribute to SE-induced neuroinflammation. Scavenging ROS also attenuated phosphorylation of ribosomal protein S6, the downstream target of the mammalian target of rapamycin (mTOR) pathway indicating that this pathway might provide one mechanistic link between SE-induced ROS production and inflammation. Together, these results demonstrate that ROS contribute to SE-induced cytokine production and antioxidant treatment may offer a novel approach to control neuroinflammation in epilepsy.
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12
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Park HJ, Kim SK, Kang WS, Park JK, Kim YJ, Nam M, Kim JW, Chung JH. Association between IRS1 Gene Polymorphism and Autism Spectrum Disorder: A Pilot Case-Control Study in Korean Males. Int J Mol Sci 2016; 17:ijms17081227. [PMID: 27483248 PMCID: PMC5000625 DOI: 10.3390/ijms17081227] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/13/2016] [Accepted: 07/25/2016] [Indexed: 11/16/2022] Open
Abstract
The insulin-like growth factor (IGF) pathway is thought to play an important role in brain development. Altered levels of IGFs and their signaling regulators have been shown in autism spectrum disorder (ASD) patients. In this study, we investigated whether coding region single-nucleotide polymorphisms (cSNPs) of the insulin receptor substrates (IRS1 and IRS2), key mediators of the IGF pathway, were associated with ASD in Korean males. Two cSNPs (rs1801123 of IRS1, and rs4773092 of IRS2) were genotyped using direct sequencing in 180 male ASD patients and 147 male control subjects. A significant association between rs1801123 of IRS1 and ASD was shown in additive (p = 0.022, odds ratio (OR) = 0.66, 95% confidence interval (CI) = 0.46–0.95) and dominant models (p = 0.013, OR = 0.57, 95% CI = 0.37–0.89). Allele frequency analysis also showed an association between rs1801123 and ASD (p = 0.022, OR = 0.66, 95% CI = 0.46–0.94). These results suggest that IRS1 may contribute to the susceptibility of ASD in Korean males.
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Affiliation(s)
- Hae Jeong Park
- Kohwang Medical Research Institute, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Su Kang Kim
- Kohwang Medical Research Institute, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Won Sub Kang
- Department of Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Jin Kyung Park
- Department of Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Young Jong Kim
- Department of Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Min Nam
- Seoul Metropolitan Eunpyeong Hospital, Seoul 06801, Korea.
| | - Jong Woo Kim
- Department of Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Joo-Ho Chung
- Kohwang Medical Research Institute, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
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13
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Higdon R, Earl RK, Stanberry L, Hudac CM, Montague E, Stewart E, Janko I, Choiniere J, Broomall W, Kolker N, Bernier RA, Kolker E. The promise of multi-omics and clinical data integration to identify and target personalized healthcare approaches in autism spectrum disorders. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2016; 19:197-208. [PMID: 25831060 DOI: 10.1089/omi.2015.0020] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Complex diseases are caused by a combination of genetic and environmental factors, creating a difficult challenge for diagnosis and defining subtypes. This review article describes how distinct disease subtypes can be identified through integration and analysis of clinical and multi-omics data. A broad shift toward molecular subtyping of disease using genetic and omics data has yielded successful results in cancer and other complex diseases. To determine molecular subtypes, patients are first classified by applying clustering methods to different types of omics data, then these results are integrated with clinical data to characterize distinct disease subtypes. An example of this molecular-data-first approach is in research on Autism Spectrum Disorder (ASD), a spectrum of social communication disorders marked by tremendous etiological and phenotypic heterogeneity. In the case of ASD, omics data such as exome sequences and gene and protein expression data are combined with clinical data such as psychometric testing and imaging to enable subtype identification. Novel ASD subtypes have been proposed, such as CHD8, using this molecular subtyping approach. Broader use of molecular subtyping in complex disease research is impeded by data heterogeneity, diversity of standards, and ineffective analysis tools. The future of molecular subtyping for ASD and other complex diseases calls for an integrated resource to identify disease mechanisms, classify new patients, and inform effective treatment options. This in turn will empower and accelerate precision medicine and personalized healthcare.
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Affiliation(s)
- Roger Higdon
- 1 Bioinformatics and High-Throughput Analysis Laboratory, Seattle Children's Research Institute , Seattle, Washington
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Krishnan N, Krishnan K, Connors CR, Choy MS, Page R, Peti W, Van Aelst L, Shea SD, Tonks NK. PTP1B inhibition suggests a therapeutic strategy for Rett syndrome. J Clin Invest 2015. [PMID: 26214522 DOI: 10.1172/jci80323] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The X-linked neurological disorder Rett syndrome (RTT) presents with autistic features and is caused primarily by mutations in a transcriptional regulator, methyl CpG-binding protein 2 (MECP2). Current treatment options for RTT are limited to alleviating some neurological symptoms; hence, more effective therapeutic strategies are needed. We identified the protein tyrosine phosphatase PTP1B as a therapeutic candidate for treatment of RTT. We demonstrated that the PTPN1 gene, which encodes PTP1B, was a target of MECP2 and that disruption of MECP2 function was associated with increased levels of PTP1B in RTT models. Pharmacological inhibition of PTP1B ameliorated the effects of MECP2 disruption in mouse models of RTT, including improved survival in young male (Mecp2-/y) mice and improved behavior in female heterozygous (Mecp2-/+) mice. We demonstrated that PTP1B was a negative regulator of tyrosine phosphorylation of the tyrosine kinase TRKB, the receptor for brain-derived neurotrophic factor (BDNF). Therefore, the elevated PTP1B that accompanies disruption of MECP2 function in RTT represents a barrier to BDNF signaling. Inhibition of PTP1B led to increased tyrosine phosphorylation of TRKB in the brain, which would augment BDNF signaling. This study presents PTP1B as a mechanism-based therapeutic target for RTT, validating a unique strategy for treating the disease by modifying signal transduction pathways with small-molecule drugs.
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15
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The need for a comprehensive molecular characterization of autism spectrum disorders. Int J Neuropsychopharmacol 2014; 17:651-73. [PMID: 24229490 DOI: 10.1017/s146114571300117x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Autism spectrum disorders (ASD) are a heterogeneous group of disorders which have complex behavioural phenotypes. Although ASD is a highly heritable neuropsychiatric disorder, genetic research alone has not provided a profound understanding of the underlying causes. Recent developments using biochemical tools such as transcriptomics, proteomics and cellular models, will pave the way to gain new insights into the underlying pathological pathways. This review addresses the state-of-the-art in the search for molecular biomarkers for ASD. In particular, the most important findings in the biochemical field are highlighted and the need for establishing streamlined interaction between behavioural studies, genetics and proteomics is stressed. Eventually, these approaches will lead to suitable translational ASD models and, therefore, a better disease understanding which may facilitate novel drug discovery efforts in this challenging field.
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16
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Allen SJ, Watson JJ, Shoemark DK, Barua NU, Patel NK. GDNF, NGF and BDNF as therapeutic options for neurodegeneration. Pharmacol Ther 2013; 138:155-75. [PMID: 23348013 DOI: 10.1016/j.pharmthera.2013.01.004] [Citation(s) in RCA: 565] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 01/07/2013] [Indexed: 12/16/2022]
Abstract
Glial cell-derived neurotrophic factor (GDNF), and the neurotrophin nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are important for the survival, maintenance and regeneration of specific neuronal populations in the adult brain. Depletion of these neurotrophic factors has been linked with disease pathology and symptoms, and replacement strategies are considered as potential therapeutics for neurodegenerative diseases such as Parkinson's, Alzheimer's and Huntington's diseases. GDNF administration has recently been shown to be an effective treatment for Parkinson's disease, with clinical trials currently in progress. Trials with NGF for Alzheimer's disease are ongoing, with some degree of success. Preclinical results using BDNF also show much promise, although there are accompanying difficulties. Ultimately, the administration of a therapy involving proteins in the brain has inherent problems. Because of the blood-brain-barrier, the protein must be infused directly, produced by viral constructs, secreted from implanted protein-secreting cells or actively transported across the brain. An alternative to this is the use of a small molecule agonist, a modulator or enhancer targeting the associated receptors. We evaluate these neurotrophic factors as potential short or long-term treatments, weighing up preclinical and clinical results with the possible effects on the underlying neurodegenerative process.
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17
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Li W, Pozzo-Miller L. BDNF deregulation in Rett syndrome. Neuropharmacology 2013; 76 Pt C:737-46. [PMID: 23597512 DOI: 10.1016/j.neuropharm.2013.03.024] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/25/2013] [Accepted: 03/15/2013] [Indexed: 12/21/2022]
Abstract
BDNF is the best-characterized neurotrophin in terms of its gene structure and modulation, secretion processing, and signaling cascades following its release. In addition to diverse features at the genetic and molecular levels, the abundant expression in several regions of the central nervous system has implicated BDNF as a potent modulator in many aspects of neuronal development, as well as synaptic transmission and plasticity. Impairments in any of these critical functions likely contribute to a wide array of neurodevelopmental, neurodegenerative, and neuropsychiatric diseases. In this review, we focus on a prevalent neurodevelopmental disorder, Rett syndrome (RTT), which afflicts 1:15,000 women world-wide. We describe the consequences of loss-of-function mutations in the gene encoding the transcription factor methyl-CpG binding protein 2 (MeCP2) in RTT, and then elaborate on the current understanding of how MeCP2 controls BDNF expression. Finally, we discuss the literature regarding alterations in BDNF levels in RTT individuals and MeCP2-based mouse models, as well as recent progress in searching for rational therapeutic interventions. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Affiliation(s)
- Wei Li
- Department of Neurobiology, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
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18
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Insulin-like growth factor and the etiology of autism. Med Hypotheses 2013; 80:475-80. [DOI: 10.1016/j.mehy.2013.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 01/09/2013] [Indexed: 11/24/2022]
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Stamou M, Streifel KM, Goines PE, Lein PJ. Neuronal connectivity as a convergent target of gene × environment interactions that confer risk for Autism Spectrum Disorders. Neurotoxicol Teratol 2013; 36:3-16. [PMID: 23269408 PMCID: PMC3610799 DOI: 10.1016/j.ntt.2012.12.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 11/12/2012] [Accepted: 12/17/2012] [Indexed: 11/21/2022]
Abstract
Evidence implicates environmental factors in the pathogenesis of Autism Spectrum Disorders (ASD). However, the identity of specific environmental chemicals that influence ASD risk, severity or treatment outcome remains elusive. The impact of any given environmental exposure likely varies across a population according to individual genetic substrates, and this increases the difficulty of identifying clear associations between exposure and ASD diagnoses. Heritable genetic vulnerabilities may amplify adverse effects triggered by environmental exposures if genetic and environmental factors converge to dysregulate the same signaling systems at critical times of development. Thus, one strategy for identifying environmental risk factors for ASD is to screen for environmental factors that modulate the same signaling pathways as ASD susceptibility genes. Recent advances in defining the molecular and cellular pathology of ASD point to altered patterns of neuronal connectivity in the developing brain as the neurobiological basis of these disorders. Studies of syndromic ASD and rare highly penetrant mutations or CNVs in ASD suggest that ASD risk genes converge on several major signaling pathways linked to altered neuronal connectivity in the developing brain. This review briefly summarizes the evidence implicating dysfunctional signaling via Ca(2+)-dependent mechanisms, extracellular signal-regulated kinases (ERK)/phosphatidylinositol-3-kinases (PI3K) and neuroligin-neurexin-SHANK as convergent molecular mechanisms in ASD, and then discusses examples of environmental chemicals for which there is emerging evidence of their potential to interfere with normal neuronal connectivity via perturbation of these signaling pathways.
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Affiliation(s)
- Marianna Stamou
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Karin M. Streifel
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Paula E. Goines
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
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20
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Berger-Sweeney J. Cognitive deficits in Rett syndrome: What we know and what we need to know to treat them. Neurobiol Learn Mem 2011; 96:637-46. [DOI: 10.1016/j.nlm.2011.05.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/04/2011] [Accepted: 05/13/2011] [Indexed: 10/18/2022]
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Riva D, Bulgheroni S, Aquino D, Di Salle F, Savoiardo M, Erbetta A. Basal forebrain involvement in low-functioning autistic children: a voxel-based morphometry study. AJNR Am J Neuroradiol 2011; 32:1430-5. [PMID: 21700792 DOI: 10.3174/ajnr.a2527] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Imaging studies have revealed brain abnormalities in the regions involved in functions impaired in ASD (social relations, verbal and nonverbal communication, and adaptive behavior). We performed a VBM whole-brain analysis to assess the areas involved in autistic children with DD. MATERIALS AND METHODS Twenty-one developmentally delayed children with ASD (aged 3-10 years) were compared with 21 controls matched for age, sex, and sociocultural background. All ASD cases had been diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria, with the Autism Diagnostic Observation Schedule-Generic, and the Autism Diagnostic Interview-Revised. The VBM data, covaried with intelligence quotient, age, and brain volume, were analyzed. RESULTS ASD patients showed a pattern of regional GM reduction symmetrically affecting the basal forebrain, accumbens nucleus, cerebellar hemispheres, and perisylvian regions, including insula and putamen. Asymmetric involvement of GM was observed in other brain regions functionally connected to the basal forebrain, ie, an area located close to the medial and ventral surface of the frontal lobe. No regional WM differences were observed between the 2 groups. No significant differences between patients and controls were found regarding total brain volume, GM, and WM. CONCLUSIONS In children with ASD and DD, the novel finding of our VBM study was the demonstration of reduced GM volume in the basal forebrain and the areas connected with it. This system is involved in social behavior, communication, and cognitive skills. Whether the involvement of the basal forebrain is characteristic of ASD or is related to the DD present in our patients needs further investigation.
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Affiliation(s)
- D Riva
- Division of Developmental Neurology, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy.
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22
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Landi S, Putignano E, Boggio EM, Giustetto M, Pizzorusso T, Ratto GM. The short-time structural plasticity of dendritic spines is altered in a model of Rett syndrome. Sci Rep 2011; 1:45. [PMID: 22355564 PMCID: PMC3216532 DOI: 10.1038/srep00045] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 07/04/2011] [Indexed: 11/09/2022] Open
Abstract
The maturation of excitatory transmission comes about through a developmental period in which dendritic spines are highly motile and their number, form and size are rapidly changing. Surprisingly, although these processes are crucial for the formation of cortical circuitry, little is known about possible alterations of these processes in brain disease. By means of acute in vivo 2-photon imaging we show that the dynamic properties of dendritic spines of layer V cortical neurons are deeply affected in a mouse model of Rett syndrome (RTT) at a time around P25 when the neuronal phenotype of the disease is still mild. Then, we show that 24h after a subcutaneous injection of IGF-1 spine dynamics is restored. Our study demonstrates that spine dynamics in RTT mice is severely impaired early during development and suggest that treatments for RTT should be started very early in order to reestablish a normal period of spine plasticity.
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Affiliation(s)
- Silvia Landi
- NEST, Scuola Normale Superiore, Pisa, Italy; NEST Institute Nanoscience CNR, Pisa, Italy
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Chapleau CA, Larimore JL, Theibert A, Pozzo-Miller L. Modulation of dendritic spine development and plasticity by BDNF and vesicular trafficking: fundamental roles in neurodevelopmental disorders associated with mental retardation and autism. J Neurodev Disord 2011; 1:185-96. [PMID: 19966931 PMCID: PMC2788955 DOI: 10.1007/s11689-009-9027-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The process of axonal and dendritic development establishes the synaptic circuitry of the central nervous system (CNS) and is the result of interactions between intrinsic molecular factors and the external environment. One growth factor that has a compelling function in neuronal development is the neurotrophin brain-derived neurotrophic factor (BDNF). BDNF participates in axonal and dendritic differentiation during embryonic stages of neuronal development, as well as in the formation and maturation of dendritic spines during postnatal development. Recent studies have also implicated vesicular trafficking of BDNF via secretory vesicles, and both secretory and endosomal trafficking of vesicles containing synaptic proteins, such as neurotransmitter and neurotrophin receptors, in the regulation of axonal and dendritic differentiation, and in dendritic spine morphogenesis. Several genes that are either mutated or deregulated in neurodevelopmental disorders associated with mental retardation have now been identified, and several mouse models of these disorders have been generated and characterized. Interestingly, abnormalities in dendritic and synaptic structure are consistently observed in human neurodevelopmental disorders associated with mental retardation, and in mouse models of these disorders as well. Abnormalities in dendritic and synaptic differentiation are thought to underlie altered synaptic function and network connectivity, thus contributing to the clinical outcome. Here, we review the roles of BDNF and vesicular trafficking in axonal and dendritic differentiation in the context of dendritic and axonal morphological impairments commonly observed in neurodevelopmental disorders associated with mental retardation.
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Affiliation(s)
- Christopher A Chapleau
- Department of Neurobiology, Civitan International Research Center, Evelyn McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Abstract
Autism spectrum disorders (ASDs) are pervasive developmental disorders that frequently involve a triad of deficits in social skills, communication and language. For the underlying neurobiology of these symptoms, disturbances in neuronal development and synaptic plasticity have been discussed. The physiological development, regulation and survival of specific neuronal populations shaping neuronal plasticity require the so-called 'neurotrophic factors' (NTFs). These regulate cellular proliferation, migration, differentiation and integrity, which are also affected in ASD. Therefore, NTFs have gained increasing attention in ASD research. This review provides an overview and explores the key role of NTFs in the aetiology of ASD. We have also included evidence derived from neurochemical investigations, gene association studies and animal models. By focussing on the role of NTFs in ASD, we intend to further elucidate the puzzling aetiology of these conditions.
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Affiliation(s)
- T Nickl-Jockschat
- Department of Psychiatry and Psychotherapy, RWTH Aachen University, Aachen, Germany
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Glatiramer acetate (GA, Copolymer-1) an hypothetical treatment option for Rett syndrome. Med Hypotheses 2010; 76:190-3. [PMID: 20951500 DOI: 10.1016/j.mehy.2010.09.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 09/04/2010] [Accepted: 09/08/2010] [Indexed: 11/24/2022]
Abstract
Rett syndrome (RTT) is an X-linked dominant postnatal severe and disabling neurodevelopmental disorder which is the second most common cause for genetic mental retardation in girls and the first pervasive disorder with a known genetic basis. The syndrome is primarily caused by mutations in the Methyl CpG binding protein 2 (MECP2) gene on Xq28. Its protein product MeCP2 acts as a transcriptional repressor or activator depending on the target gene associated. Brain derived neurotrophic factor (BDNF) is a neurotrophic factor playing a major role in neuronal survival, neurogenesis and plasticity. It has been identified as a major MeCP2 target through a candidate gene approach and abnormalities in BDNF homeostasis are believed to contribute to the neurologic phenotype and pato-physiology of part of the symptoms in Mecp2 null mice that show progressive deficits in its expression. Based on the presumed role of BDNF in the pathophysiology of Rett syndrome it is reasonable to assume that interventions that will elevate its levels in the brain of RTT patients will be of therapeutic benefit. Glatiramer acetate (GA, Copolymer 1, Copaxone) an immunomodulator with proven safety and efficacy in Multiple Sclerosis has been reported to cause elevated secretion of BDNF both in animal model and in MS patients. Our hypothesis is that continuous treatment of patients with RTT with Glatiramer acetate might lead to an increase in their brain's BDNF content and an improvement in at least part of the syndrome symptomatology while being safe to use and well tolerated in this population. In a pilot preliminary study we have shown that GA cause elevation of BDNF expression up to the level in naïve control mice in several cortical areas in the Mecp2 mutated mouse brain, but as of yet did not examine the behavioral aspects of this elevation.
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Schaevitz LR, Moriuchi JM, Nag N, Mellot TJ, Berger-Sweeney J. Cognitive and social functions and growth factors in a mouse model of Rett syndrome. Physiol Behav 2010; 100:255-63. [PMID: 20045424 DOI: 10.1016/j.physbeh.2009.12.025] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 11/18/2022]
Abstract
Rett syndrome (RTT) is an autism-spectrum disorder caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). Abnormalities in social behavior, stereotyped movements, and restricted interests are common features in both RTT and classic autism. While mouse models of both RTT and autism exist, social behaviors have not been explored extensively in mouse models of RTT. Here, we report cognitive and social abnormalities in Mecp2(1lox) null mice, an animal model of RTT. The null mice show severe deficits in short- and long-term object recognition memories, reminiscent of the severe cognitive deficits seen in RTT girls. Social behavior, however, is abnormal in that the null mice spend more time in contact with stranger mice than do wildtype controls. These findings are consistent with reports of increased reciprocal social interaction in RTT girls relative to classic autism. We also report here that the levels of the neurotrophins brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and nerve growth factor (NGF) are decreased in the hippocampus of the null mice, and discuss how this may provide an underlying mechanism for both the cognitive deficits and the increased motivation for social contact observed in the Mecp2(1lox) null mice. These studies support a differential etiology between RTT and autism, particularly with respect to sociability deficits.
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Affiliation(s)
- Laura R Schaevitz
- Department of Biological Sciences, Wellesley College, Wellesley MA 02481, United States
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Larimore JL, Chapleau CA, Kudo S, Theibert A, Percy AK, Pozzo-Miller L. Bdnf overexpression in hippocampal neurons prevents dendritic atrophy caused by Rett-associated MECP2 mutations. Neurobiol Dis 2009; 34:199-211. [PMID: 19217433 PMCID: PMC2726722 DOI: 10.1016/j.nbd.2008.12.011] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/29/2008] [Accepted: 12/13/2008] [Indexed: 11/27/2022] Open
Abstract
The expression of the methylated DNA-binding protein MeCP2 increases during neuronal development, which suggests that this epigenetic factor is crucial for neuronal terminal differentiation. We evaluated dendritic and axonal development in embryonic day-18 hippocampal neurons in culture by measuring total length and counting branch point numbers at 4 days in vitro, well before synapse formation. Pyramidal neurons transfected with a plasmid encoding a small hairpin RNA (shRNA) to knockdown endogenous Mecp2 had shorter dendrites than control untransfected neurons, without detectable changes in axonal morphology. On the other hand, overexpression of wildtype (wt) human MECP2 increased dendritic branching, in addition to axonal branching and length. Consistent with reduced neuronal growth and complexity in Rett syndrome (RTT) brains, overexpression of human MECP2 carrying missense mutations common in RTT individuals (R106W or T158M) reduced dendritic and axonal length. One of the targets of MeCP2 transcriptional control is the Bdnf gene. Indeed, endogenous Mecp2 knockdown increased the intracellular levels of BDNF protein compared to untransfected neurons, suggesting that MeCP2 represses Bdnf transcription. Surprisingly, overexpression of wt MECP2 also increased BDNF levels, while overexpression of RTT-associated MECP2 mutants failed to affect BDNF levels. The extracellular BDNF scavenger TrkB-Fc prevented dendritic overgrowth in wt MECP2-overexpressing neurons, while overexpression of the Bdnf gene reverted the dendritic atrophy caused by Mecp2-knockdown. However, this effect was only partial, since Bdnf increased dendritic length only to control levels in mutant MECP2-overexpressing neurons, but not as much as in Bdnf-transfected cells. Our results demonstrate that MeCP2 plays varied roles in dendritic and axonal development during neuronal terminal differentiation, and that some of these effects are mediated by autocrine actions of BDNF.
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Affiliation(s)
- Jennifer L. Larimore
- Department of Neurobiology, Evelyn McKnight Brain Institute, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
| | - Christopher A. Chapleau
- Department of Neurobiology, Evelyn McKnight Brain Institute, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
| | - Shinichi Kudo
- Hokkaido Institute of Public Health, Kita-19, Nishi-12, Kita-ku, Sapporo 060-0819, Japan
| | - Anne Theibert
- Department of Neurobiology, Evelyn McKnight Brain Institute, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
| | - Alan K. Percy
- Department of Pediatrics, UAB, Birmingham, AL 35294-2182, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology, Evelyn McKnight Brain Institute, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
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Ogier M, Katz DM. Breathing dysfunction in Rett syndrome: understanding epigenetic regulation of the respiratory network. Respir Physiol Neurobiol 2009; 164:55-63. [PMID: 18534925 DOI: 10.1016/j.resp.2008.04.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 04/09/2008] [Accepted: 04/10/2008] [Indexed: 11/17/2022]
Abstract
Severely arrhythmic breathing is a hallmark of Rett syndrome (RTT) and profoundly affects quality of life for patients and their families. The last decade has seen the identification of the disease-causing gene, methyl-CpG-binding protein 2 (Mecp2) and the development of mouse models that phenocopy many aspects of the human syndrome, including breathing dysfunction. Recent studies have begun to characterize the breathing phenotype of Mecp2 mutant mice and to define underlying electrophysiological and neurochemical deficits. The picture that is emerging is one of defects in synaptic transmission throughout the brainstem respiratory network associated with abnormal expression in several neurochemical signaling systems, including brain-derived neurotrophic factor (BDNF), biogenic amines and gamma-amino-butyric acid (GABA). Based on such findings, potential therapeutic strategies aimed at improving breathing by targeting deficits in neurochemical signaling are being explored. This review details our current understanding of respiratory dysfunction and underlying mechanisms in RTT with a particular focus on insights gained from mouse models.
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Affiliation(s)
- Michael Ogier
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4975, USA
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Nag N, Mellott TJ, Berger-Sweeney JE. Effects of postnatal dietary choline supplementation on motor regional brain volume and growth factor expression in a mouse model of Rett syndrome. Brain Res 2008; 1237:101-9. [DOI: 10.1016/j.brainres.2008.08.042] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 08/12/2008] [Accepted: 08/12/2008] [Indexed: 12/29/2022]
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Abstract
The postnatal neurodevelopmental disorder Rett syndrome (RTT) is caused by mutations in the gene encoding methyl-CpG binding protein 2 (MeCP2), a transcriptional repressor involved in chromatin remodeling and the modulation of RNA splicing. MECP2 aberrations result in a constellation of neuropsychiatric abnormalities, whereby both loss of function and gain in MECP2 dosage lead to similar neurological phenotypes. Recent studies demonstrate disease reversibility in RTT mouse models, suggesting that the neurological defects in MECP2 disorders are not permanent. To investigate the potential for restoring neuronal function in RTT patients, it is essential to identify MeCP2 targets or modifiers of the phenotype that can be therapeutically modulated. Moreover, deciphering the molecular underpinnings of RTT is likely to contribute to the understanding of the pathogenesis of a broader class of neuropsychiatric disorders.
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Affiliation(s)
- Maria Chahrour
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
Improving clinical tests are allowing us to more precisely classify autism spectrum disorders and diagnose them at earlier ages. This raises the possibility of earlier and potentially more effective therapeutic interventions. To fully capitalize on this opportunity, however, will require better understanding of the neurobiological changes underlying this devastating group of developmental disorders. It is becoming clear that the normal trajectory of neurodevelopment is altered in autism, with aberrations in brain growth, neuronal patterning and cortical connectivity. Changes to the structure and function of synapses and dendrites have also been strongly implicated in the pathology of autism by morphological, genetic and animal modeling studies. Finally, environmental factors are likely to interact with the underlying genetic profile, and foster the clinical heterogeneity seen in autism spectrum disorders. In this review we attempt to link the molecular pathways altered in autism to the neurodevelopmental and clinical changes that characterize the disease. We focus on signaling molecules such as neurotrophin, Reelin, PTEN and hepatocyte growth factor, neurotransmitters such as serotonin and glutamate, and synaptic proteins such as neurexin, SHANK and neuroligin. We also discuss evidence implicating oxidative stress, neuroglial activation and neuroimmunity in autism.
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Affiliation(s)
- Carlos A Pardo
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287. USA.
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Mills JL, Hediger ML, Molloy CA, Chrousos GP, Manning-Courtney P, Yu KF, Brasington M, England LJ. Elevated levels of growth-related hormones in autism and autism spectrum disorder. Clin Endocrinol (Oxf) 2007; 67:230-7. [PMID: 17547689 DOI: 10.1111/j.1365-2265.2007.02868.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Children with autism are known to have larger head circumferences; whether they are above average in height and weight is less clear. Moreover, little is known about growth-related hormone levels in children with autism. We investigated whether children with autism were taller and heavier, and whether they had higher levels of growth-related hormones than control children did. DESIGN A case-control study design was employed. PATIENTS Boys with autism spectrum disorder (ASD) or autism (n = 71) and age-matched control boys (n = 59) were evaluated at Cincinnati Children's Hospital. MEASUREMENTS Height, weight and head circumference were measured. Blood samples were assayed for IGF-1 and 2, IGFBP-3, growth hormone binding protein (GHBP) and for dehydroepiandrosterone (DHEA) and DHEA sulphate (DHEAS). RESULTS Subjects with autism/ASD had significantly (P = 0.03) greater head circumferences (mean z-score 1.24, SD 1.35) than controls (mean z-score 0.78, SD 0.93). Subjects with autism also had significantly (P = 0.01) greater weights (mean z-score 0.91, SD 1.13) than controls (mean z-score 0.41, SD 1.11). Height did not differ significantly between groups (P = 0.65); subjects with autism/ASD had significantly (P = 0.003) higher body mass indices (BMI) (mean z-score 0.85, SD 1.19) than controls (mean z-score 0.24, SD 1.17). Levels of IGF-1, IGF-2, IGFBP-3 and GHBP in the group with autism/ASD were all significantly higher (all P < or = 0.0001) than in controls. CONCLUSIONS Children with autism/ASD had significantly higher levels of many growth-related hormones: IGF-1, IGF-2, IGFBP-3 and GHBP. These findings could help explain the significantly larger head circumferences and higher weights and BMIs seen in these subjects. Future studies should examine the potential role of growth-related hormones in the pathophysiology of autism.
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Affiliation(s)
- James L Mills
- Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health/DHHS, Bethesda, MD 20892, USA.
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Amaral MD, Chapleau CA, Pozzo-Miller L. Transient receptor potential channels as novel effectors of brain-derived neurotrophic factor signaling: potential implications for Rett syndrome. Pharmacol Ther 2007; 113:394-409. [PMID: 17118456 PMCID: PMC1862519 DOI: 10.1016/j.pharmthera.2006.09.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 09/26/2006] [Indexed: 02/07/2023]
Abstract
In addition to their prominent role as survival signals for neurons in the developing nervous system, neurotrophins have established their significance in the adult brain as well, where their modulation of synaptic transmission and plasticity may participate in associative learning and memory. These crucial activities are primarily the result of neurotrophin regulation of intracellular Ca(2+) homeostasis and, ultimately, changes in gene expression. Outlined in the following review is a synopsis of neurotrophin signaling with a particular focus upon brain-derived neurotrophic factor (BDNF) and its role in hippocampal synaptic plasticity and neuronal Ca(2+) homeostasis. Neurotrophin signaling through tropomyosin-related kinase (Trk) and pan-neurotrophin receptor 75 kD (p75(NTR)) receptors are also discussed, reviewing recent results that indicate signaling through these two receptor modalities leads to opposing cellular outcomes. We also provide an intriguing look into the transient receptor potential channel (TRPC) family of ion channels as distinctive targets of BDNF signaling; these channels are critical for capacitative Ca(2+) entry, which, in due course, mediates changes in neuronal structure including dendritic spine density. Finally, we expand these topics into an exploration of mental retardation (MR), in particular Rett Syndrome (RTT), where dendritic spine abnormalities may underlie cognitive impairments. We propose that understanding the role of neurotrophins in synapse formation, plasticity, and maintenance will make fundamental contributions to the development of therapeutic strategies to improve cognitive function in developmental disorders associated with MR.
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Affiliation(s)
- Michelle D Amaral
- Department of Neurobiology, Civitan International Research Center, McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA
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Augustin H, Grosjean Y, Chen K, Sheng Q, Featherstone DE. Nonvesicular release of glutamate by glial xCT transporters suppresses glutamate receptor clustering in vivo. J Neurosci 2007; 27:111-23. [PMID: 17202478 PMCID: PMC2193629 DOI: 10.1523/jneurosci.4770-06.2007] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We hypothesized that cystine/glutamate transporters (xCTs) might be critical regulators of ambient extracellular glutamate levels in the nervous system and that misregulation of this glutamate pool might have important neurophysiological and/or behavioral consequences. To test this idea, we identified and functionally characterized a novel Drosophila xCT gene, which we subsequently named "genderblind" (gb). Genderblind is expressed in a previously overlooked subset of peripheral and central glia. Genetic elimination of gb causes a 50% reduction in extracellular glutamate concentration, demonstrating that xCT transporters are important regulators of extracellular glutamate. Consistent with previous studies showing that extracellular glutamate regulates postsynaptic glutamate receptor clustering, gb mutants show a large (200-300%) increase in the number of postsynaptic glutamate receptors. This increase in postsynaptic receptor abundance is not accompanied by other obvious synaptic changes and is completely rescued when synapses are cultured in wild-type levels of glutamate. Additional in situ pharmacology suggests that glutamate-mediated suppression of glutamate receptor clustering depends on receptor desensitization. Together, our results suggest that (1) xCT transporters are critical for regulation of ambient extracellular glutamate in vivo; (2) ambient extracellular glutamate maintains some receptors constitutively desensitized in vivo; and (3) constitutive desensitization of ionotropic glutamate receptors suppresses their ability to cluster at synapses.
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Affiliation(s)
- Hrvoje Augustin
- Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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Shinohe A, Hashimoto K, Nakamura K, Tsujii M, Iwata Y, Tsuchiya KJ, Sekine Y, Suda S, Suzuki K, Sugihara GI, Matsuzaki H, Minabe Y, Sugiyama T, Kawai M, Iyo M, Takei N, Mori N. Increased serum levels of glutamate in adult patients with autism. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:1472-7. [PMID: 16863675 DOI: 10.1016/j.pnpbp.2006.06.013] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2006] [Revised: 06/08/2006] [Accepted: 06/15/2006] [Indexed: 11/21/2022]
Abstract
BACKGROUND Precise mechanisms underlying the pathophysiology of autism are currently unknown. Given the major role of glutamate in brain development, we have hypothesized that glutamatergic neurotransmission plays a role in the pathophysiology of autism. In this study, we studied whether amino acids (glutamate, glutamine, glycine, D-serine, and L-serine) related to glutamatergic neurotransmission are altered in serum of adult patients with autism. METHODS We measured serum levels of amino acids in 18 male adult patients with autism and age-matched 19 male healthy subjects using high-performance liquid chromatography. RESULTS Serum levels (mean = 89.2 microM, S.D. = 21.5) of glutamate in the patients with autism were significantly (t = -4.48, df = 35, p < 0.001) higher than those (mean = 61.1 microM, S.D. = 16.5) of normal controls. In contrast, serum levels of other amino acids (glutamine, glycine, d-serine, l-serine) in the patients with autism did not differ from those of normal controls. There was a positive correlation (r = 0.523, p = 0.026) between serum glutamate levels and Autism Diagnostic Interview-Revised (ADI-R) social scores in patients. CONCLUSIONS The present study suggests that an abnormality in glutamatergic neurotransmission may play a role in the pathophysiology of autism.
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Affiliation(s)
- Atsuko Shinohe
- Department of Psychiatry and Neurology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan
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Chen H, Tung YC, Li B, Iqbal K, Grundke-Iqbal I. Trophic factors counteract elevated FGF-2-induced inhibition of adult neurogenesis. Neurobiol Aging 2006; 28:1148-62. [PMID: 16859812 DOI: 10.1016/j.neurobiolaging.2006.05.036] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 05/22/2006] [Accepted: 05/24/2006] [Indexed: 01/28/2023]
Abstract
The dentate gyrus of adult mammalian brain contains neural progenitor cells with self-renewal and multi-lineage potential. The lineage and maturation of the neural progenitors are determined by the composition and levels of the trophic factors in their microenvironment. In Alzheimer disease (AD) brain, especially the hippocampus, the level of basic fibroblast growth factor (FGF-2) is markedly elevated. Here we show that elevated FGF-2 enhances the division and nestin levels of cultured adult rat hippocampal progenitors but impairs neuronal lineage determination and maturation of these cells in culture. The trophic factors ciliary neurotrophic factor (CNTF), glial-derived neurotrophic factor (GDNF), and insulin-like growth factors-1 and -2 (IGF-1, IGF-2) as well as an Alzheimer peptidergic drug, Cerebrolysin((R)) (CL), in which we found these neurotrophic activities, counteract the effect of FGF-2 in inducing neuronal lineage (early neurogenesis). Whereas CNTF is the most active of the neurotrophic factors studied in promoting neurogenesis, CL, probably because of a combined effect of these factors, induces similar changes but without inhibiting cell proliferation. These findings suggest that CNTF, GDNF, IGF-1, and IGF-2 are promising therapeutic targets for AD and other diseases in which neurogenesis is probably inhibited.
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Affiliation(s)
- Honghui Chen
- New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314-6399, USA.
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Kerr AM, Archer HL, Evans JC, Prescott RJ, Gibbon F. People with MECP2 mutation-positive Rett disorder who converse. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2006; 50:386-94. [PMID: 16629931 DOI: 10.1111/j.1365-2788.2005.00786.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND People with useful speech after regression constitute a distinct group of those with mutation-positive Rett disorder, 6% (20/331) reported among mutation-positive people in the British Survey. We aimed to determine the physical, mental and genetic characteristics of this group and to gain insight into their experience of Rett syndrome. METHODS Clinical and molecular data for people with Rett, aged 10 or more years at follow-up (the study group, n = 13), with the ability to converse and a MECP2 mutation are presented. They were compared with an age-matched control group (n = 110), who could not converse and had a pathogenic MECP2 mutation. RESULTS The study group differed significantly from the control group with regard to their disease severity (P < 0.001); feeding difficulty scores (P < 0.001); health scores (P < 0.001); epilepsy (P < 0.001); head circumference (P < 0.004); age at onset of the regression period (P < 0.001) (six in the study group did not regress) and mutation frequency (C-terminal deletions P = 0.014, R133C P < 0.006). The results indicate that favourable skewing of X-inactivation is only present in a small proportion of mild cases. Speech was fragmented with a soft, breathless quality, and all but two had obviously irregular breathing. One person with an R168X mutation preferred signing to speech. All enjoyed interpersonal contact, showing affection and preferring people to objects, clearly distinguishing the condition from autism. Most were habitually anxious. Music was a source of pleasure and relaxation also providing a valuable educational asset. Even in these most able cases, understanding was severely restricted in most and little initiative was shown. CONCLUSIONS While the Rett profile is present in these people they are commonly not classic, and the presence of speech, good head growth and lack of regression may lead to missed diagnoses. A strong association was demonstrated between this milder form of the disease and R133C and C-terminal deletions.
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Affiliation(s)
- A M Kerr
- Department of Psychological Medicine, University of Glasgow, Gartnavel Royal Hospital, Glasgow, UK
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Armstrong DD. Can we relate MeCP2 deficiency to the structural and chemical abnormalities in the Rett brain? Brain Dev 2005; 27 Suppl 1:S72-S76. [PMID: 16182497 DOI: 10.1016/j.braindev.2004.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 10/29/2004] [Indexed: 11/22/2022]
Abstract
The mutated gene for Rett syndrome, MECP2, has now been identified in ninety percent of cases. Molecular biologists are immersed in the study of this gene's biology determining how its mutation could be responsible for such an enigmatic phenotype. In this paper the same question is considered, re-examining the structural phenotype of the Rett brain and asking; is MeCP2 present at the appropriate time and place in brain development to influence the structural and chemical abnormalities which characterize the Rett brain? Data from the literature and previous research suggest that MeCP2 is expressed during critical periods of brain development at several sites and in different neurons. It supports the idea that inadequate functioning of MeCP2 alters trophic factors and raises the possibility that replacement of these factors might improve brain function. The availability of mouse models now makes it possible to test such ideas.
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Affiliation(s)
- Dawna Duncan Armstrong
- Department of Pathology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA.
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Zhang FX, Lai CH, Tse YC, Shum DKY, Chan YS. Expression of Trk receptors in otolith-related neurons in the vestibular nucleus of rats. Brain Res 2005; 1062:92-100. [PMID: 16256078 DOI: 10.1016/j.brainres.2005.09.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 09/18/2005] [Accepted: 09/25/2005] [Indexed: 01/19/2023]
Abstract
The expression of the three Trk receptors (TrkA, TrkB, and TrkC) in otolith-related neurons within the vestibular nuclei of adult Sprague-Dawley rats was examined immunohistochemically. Conscious animals were subjected to sinusoidal linear acceleration along either the anterior-posterior (AP) or interaural (IA) axis on the horizontal plane. Neuronal activation was defined by Fos expression in cell nuclei. Control animals, viz labyrinthectomized rats subjected to stimulation and normal rats that remained stationary, showed only a few sporadically scattered Fos-labeled neurons. Among experimental rats, the number of Fos-labeled neurons and their distribution pattern in each vestibular subnucleus in animals stimulated along the antero-posterior axis were similar to those along the interaural axis. No apparent topography was observed among neurons activated along these two directions. Only about one-third of the Trk-immunoreactive neurons in the vestibular nucleus expressed Fos. Double-labeled Fos/TrkA, Fos/TrkB and Fos/TrkC neurons constituted 85-98% of the total number of Fos-labeled neurons in vestibular nuclear complex and its subgroups x and y. Our findings suggest that Trk receptors and their cognate neurotrophins in central otolith neurons may contribute to the modulation of gravity-related spatial information during horizontal head movements.
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Affiliation(s)
- F X Zhang
- Department of Physiology, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, China
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Abstract
Rett syndrome is a sporadic disorder (except for a few familial cases) occurring in 1 in 10,000 to 1 in 23,000 girls worldwide. It is associated with profound mental and motor handicap. About 90% of cases involve a mutation in the methyl-CpG binding protein 2 gene (MECP2). The role of this gene in the pathogenesis of this enigmatic disorder is being extensively investigated in animal models. Rett syndrome is associated with a complex phenotype that is unique in every aspect of its presentation, clinical physiology, chemistry, and pathology. Years of concentrated observations have defined the clinical presentation of classic Rett syndrome and its variants and related features (eg, neurophysiologic, radiologic, chemical, metabolic, and anatomic). This article reviews the neuropathology of Rett syndrome, which involves individual neurons, perhaps selected neurons, of decreased size, dendritic branching, and numbers of spines. This article also summarizes the studies in the human and mouse brain with Rett syndrome that are beginning to reveal the disorder's pathoetiology.
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Fukuda T, Itoh M, Ichikawa T, Washiyama K, Goto YI. Delayed Maturation of Neuronal Architecture and Synaptogenesis in Cerebral Cortex ofMecp2-Deficient Mice. J Neuropathol Exp Neurol 2005; 64:537-44. [PMID: 15977646 DOI: 10.1093/jnen/64.6.537] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We detected morphologic abnormalities in the cerebral cortex of Mecp2-hemizygous (Mecp2(-/y)) mice. The cortical thickness of both somatosensory and motor cortices in mutants did not increase after 4 weeks of age, as compared with that in wild-type male mice. The density of neurons in those areas was significantly higher in layers II/III and V of Mecp2(-/y) mice than in wild-type mice, particularly in layers II/ III after 4 weeks of age. In layer II/III of the somatosensory cortex of Mecp2(-/y) mice, the diameter of the apical dendrite was thin and the number of dendritic spines was small. Electron microscopy revealed that two-week-old mutants already had numerous premature postsynaptic densities. These results indicate that Mecp2(-/y) mice suffered delayed neuronal maturation of the cerebral cortex and that the initial neuronal changes were caused by premature synaptogenesis. Rett syndrome patients with a heterozygous mutation of Mecp2 display developmental disorders including cortical malfunctions such as mental retardation, autism, and epilepsy. Our results provide evidence of the similarity with Rett syndrome brains in some respects and suggest that MeCP2/Mecp2 plays some role in synaptogenesis.
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Affiliation(s)
- Tetsuya Fukuda
- Department of Mental Retardation and Birth Defect Research, Institute of Neuroscience, National Center for Neurology and Psychiatry, Kodaira, Tokyo, Japan
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Datta SS. ECT treatment for autism: a viable alternative for a subgroup of patients? Med Hypotheses 2005; 64:219. [PMID: 15533648 DOI: 10.1016/j.mehy.2004.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2004] [Accepted: 08/16/2004] [Indexed: 11/23/2022]
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Miller MW. Repeated episodic exposure to ethanol affects neurotrophin content in the forebrain of the mature rat. Exp Neurol 2004; 189:173-81. [PMID: 15296847 DOI: 10.1016/j.expneurol.2004.05.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Revised: 04/16/2004] [Accepted: 05/20/2004] [Indexed: 11/26/2022]
Abstract
Chronic exposure to ethanol can cause deficits in learning and memory. It has been suggested that withdrawal is potentially more damaging than the ethanol exposure per se. Therefore, we explored the effect of repeated episodic exposure to ethanol on key regulators of cortical activity, the neurotrophins. Rats were exposed to ethanol via a liquid diet for 3 days per week for 6-24 weeks. Control rats were pair-fed an isocaloric liquid diet or ad libitum fed chow and water. The concentrations of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) were determined using enzyme-linked immunosorbant assays (ELISAs). Five telencephalic structures were examined: parietal cortex, entorhinal cortex, hippocampus, the basal nucleus, and the septal nuclei. All five areas expressed each of the three neurotrophins; BDNF was most abundant and NGF the least. The parietal cortex was susceptible to ethanol exposure, NGF and BDNF content increased, and NT-3 content fell, whereas no changes were detectable in the entorhinal cortex. In the hippocampus, the amount all three neurotrophins increased following episodic ethanol exposure. Neurotrophin content in the two segments of the basal forebrain was affected; NGF and NT-3 content in the basal forebrain was reduced and NGF and BDNF content in the septal nuclei was increased by ethanol exposure. In many cases where ethanol had an effect, the change was transient so that by 24 weeks of episodic exposure, no significant changes were evident. Thus, the effects of ethanol are site- and time-dependent. This pattern differs from changes caused by chronic ethanol exposure, hence, neurotrophins must be vulnerable to the effects of withdrawal. Furthermore, the ethanol-induced changes do not appear to fit a model consistent with retrograde regulation, rather they suggest that neurotrophins act through autocrine/paracrine systems.
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Affiliation(s)
- Michael W Miller
- Department of Neuroscience and Physiology, State University of New York-Upstate Medical University, Syracuse, NY 13210, USA.
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