1
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Purushotham SS, Reddy NMN, D'Souza MN, Choudhury NR, Ganguly A, Gopalakrishna N, Muddashetty R, Clement JP. A perspective on molecular signalling dysfunction, its clinical relevance and therapeutics in autism spectrum disorder. Exp Brain Res 2022; 240:2525-2567. [PMID: 36063192 DOI: 10.1007/s00221-022-06448-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022]
Abstract
Intellectual disability (ID) and autism spectrum disorder (ASD) are neurodevelopmental disorders that have become a primary clinical and social concern, with a prevalence of 2-3% in the population. Neuronal function and behaviour undergo significant malleability during the critical period of development that is found to be impaired in ID/ASD. Human genome sequencing studies have revealed many genetic variations associated with ASD/ID that are further verified by many approaches, including many mouse and other models. These models have facilitated the identification of fundamental mechanisms underlying the pathogenesis of ASD/ID, and several studies have proposed converging molecular pathways in ASD/ID. However, linking the mechanisms of the pathogenic genes and their molecular characteristics that lead to ID/ASD has progressed slowly, hampering the development of potential therapeutic strategies. This review discusses the possibility of recognising the common molecular causes for most ASD/ID based on studies from the available models that may enable a better therapeutic strategy to treat ID/ASD. We also reviewed the potential biomarkers to detect ASD/ID at early stages that may aid in diagnosis and initiating medical treatment, the concerns with drug failure in clinical trials, and developing therapeutic strategies that can be applied beyond a particular mutation associated with ASD/ID.
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Affiliation(s)
- Sushmitha S Purushotham
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Neeharika M N Reddy
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Michelle Ninochka D'Souza
- Centre for Brain Research, Indian Institute of Science Campus, CV Raman Avenue, Bangalore, 560 012, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India
| | - Nilpawan Roy Choudhury
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Anusa Ganguly
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Niharika Gopalakrishna
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India
| | - Ravi Muddashetty
- Centre for Brain Research, Indian Institute of Science Campus, CV Raman Avenue, Bangalore, 560 012, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India
| | - James P Clement
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, 560064, India.
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2
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Grimm NB, Lee JT. Selective Xi reactivation and alternative methods to restore MECP2 function in Rett syndrome. Trends Genet 2022; 38:920-943. [PMID: 35248405 PMCID: PMC9915138 DOI: 10.1016/j.tig.2022.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
The human X-chromosome harbors only 4% of our genome but carries over 20% of genes associated with intellectual disability. Given that they inherit only one X-chromosome, males are more frequently affected by X-linked neurodevelopmental genetic disorders than females. However, despite inheriting two X-chromosomes, females can also be affected because X-chromosome inactivation enables only one of two X-chromosomes to be expressed per cell. For Rett syndrome and similar X-linked disorders affecting females, disease-specific treatments have remained elusive. However, a cure may be found within their own cells because every sick cell carries a healthy copy of the affected gene on the inactive X (Xi). Therefore, selective Xi reactivation may be a viable approach that would address the root cause of various X-linked disorders. Here, we discuss Rett syndrome and compare current approaches in the pharmaceutical pipeline to restore MECP2 function. We then focus on Xi reactivation and review available methods, lessons learned, and future directions.
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Affiliation(s)
- Niklas-Benedikt Grimm
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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3
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Kong Y, Li QB, Yuan ZH, Jiang XF, Zhang GQ, Cheng N, Dang N. Multimodal Neuroimaging in Rett Syndrome With MECP2 Mutation. Front Neurol 2022; 13:838206. [PMID: 35280272 PMCID: PMC8904872 DOI: 10.3389/fneur.2022.838206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/24/2022] [Indexed: 01/11/2023] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder characterized by severe cognitive, social, and physical impairments resulting from de novo mutations in the X-chromosomal methyl-CpG binding protein gene 2 (MECP2). While there is still no cure for RTT, exploring up-to date neurofunctional diagnostic markers, discovering new potential therapeutic targets, and searching for novel drug efficacy evaluation indicators are fundamental. Multiple neuroimaging studies on brain structure and function have been carried out in RTT-linked gene mutation carriers to unravel disease-specific imaging features and explore genotype-phenotype associations. Here, we reviewed the neuroimaging literature on this disorder. MRI morphologic studies have shown global atrophy of gray matter (GM) and white matter (WM) and regional variations in brain maturation. Diffusion tensor imaging (DTI) studies have demonstrated reduced fractional anisotropy (FA) in left peripheral WM areas, left major WM tracts, and cingulum bilaterally, and WM microstructural/network topology changes have been further found to be correlated with behavioral abnormalities in RTT. Cerebral blood perfusion imaging studies using single-photon emission CT (SPECT) or PET have evidenced a decreased global cerebral blood flow (CBF), particularly in prefrontal and temporoparietal areas, while magnetic resonance spectroscopy (MRS) and PET studies have contributed to unraveling metabolic alterations in patients with RTT. The results obtained from the available reports confirm that multimodal neuroimaging can provide new insights into a complex interplay between genes, neurotransmitter pathway abnormalities, disease-related behaviors, and clinical severity. However, common limitations related to the available studies include small sample sizes and hypothesis-based and region-specific approaches. We, therefore, conclude that this field is still in its early development phase and that multimodal/multisequence studies with improved post-processing technologies as well as combined PET–MRI approaches are urgently needed to further explore RTT brain alterations.
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Affiliation(s)
- Yu Kong
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
- *Correspondence: Yu Kong
| | - Qiu-bo Li
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, China
| | - Zhao-hong Yuan
- Department of Pediatric Rehabilitation, Affiliated Hospital of Jining Medical University, Jining, China
| | - Xiu-fang Jiang
- Department of Pediatric Rehabilitation, Affiliated Hospital of Jining Medical University, Jining, China
| | - Gu-qing Zhang
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
- Gu-qing Zhang
| | - Nan Cheng
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Na Dang
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
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4
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Fetit R, Hillary RF, Price DJ, Lawrie SM. The neuropathology of autism: A systematic review of post-mortem studies of autism and related disorders. Neurosci Biobehav Rev 2021; 129:35-62. [PMID: 34273379 DOI: 10.1016/j.neubiorev.2021.07.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/13/2021] [Accepted: 07/10/2021] [Indexed: 02/07/2023]
Abstract
Post-mortem studies allow for the direct investigation of brain tissue in those with autism and related disorders. Several review articles have focused on aspects of post-mortem abnormalities but none has brought together the entire post-mortem literature. Here, we systematically review the evidence from post-mortem studies of autism, and of related disorders that present with autistic features. The literature consists of a small body of studies with small sample sizes, but several remarkably consistent findings are evident. Cortical layering is largely undisturbed, but there are consistent reductions in minicolumn numbers and aberrant myelination. Transcriptomics repeatedly implicate abberant synaptic, metabolic, proliferation, apoptosis and immune pathways. Sufficient replicated evidence is available to implicate non-coding RNA, aberrant epigenetic profiles, GABAergic, glutamatergic and glial dysfunction in autism pathogenesis. Overall, the cerebellum and frontal cortex are most consistently implicated, sometimes revealing distinct region-specific alterations. The literature on related disorders such as Rett syndrome, Fragile X and copy number variations (CNVs) predisposing to autism is particularly small and inconclusive. Larger studies, matched for gender, developmental stage, co-morbidities and drug treatment are required.
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Affiliation(s)
- Rana Fetit
- Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
| | - Robert F Hillary
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - David J Price
- Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Stephen M Lawrie
- Division of Psychiatry, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH10 5HF, UK; Patrick Wild Centre, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, EH10 5HF, UK
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5
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Reviewing Evidence for the Relationship of EEG Abnormalities and RTT Phenotype Paralleled by Insights from Animal Studies. Int J Mol Sci 2021; 22:ijms22105308. [PMID: 34069993 PMCID: PMC8157853 DOI: 10.3390/ijms22105308] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/09/2021] [Accepted: 05/12/2021] [Indexed: 12/29/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder that is usually caused by mutations of the MECP2 gene. Patients with RTT suffer from severe deficits in motor, perceptual and cognitive domains. Electroencephalogram (EEG) has provided useful information to clinicians and scientists, from the very first descriptions of RTT, and yet no reliable neurophysiological biomarkers related to the pathophysiology of the disorder or symptom severity have been identified to date. To identify consistently observed and potentially informative EEG characteristics of RTT pathophysiology, and ascertain areas most worthy of further systematic investigation, here we review the literature for EEG abnormalities reported in patients with RTT and in its disease models. While pointing to some promising potential EEG biomarkers of RTT, our review identify areas of need to realize the potential of EEG including (1) quantitative investigation of promising clinical-EEG observations in RTT, e.g., shift of mu rhythm frequency and EEG during sleep; (2) closer alignment of approaches between patients with RTT and its animal models to strengthen the translational significance of the work (e.g., EEG measurements and behavioral states); (3) establishment of large-scale consortium research, to provide adequate Ns to investigate age and genotype effects.
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6
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Patrizi A, Awad PN, Chattopadhyaya B, Li C, Di Cristo G, Fagiolini M. Accelerated Hyper-Maturation of Parvalbumin Circuits in the Absence of MeCP2. Cereb Cortex 2021; 30:256-268. [PMID: 31038696 DOI: 10.1093/cercor/bhz085] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 02/21/2019] [Accepted: 03/29/2019] [Indexed: 12/27/2022] Open
Abstract
Methyl-CpG-binding protein 2 (MeCP2) mutations are the primary cause of Rett syndrome, a severe neurodevelopmental disorder. Cortical parvalbumin GABAergic interneurons (PV) make exuberant somatic connections onto pyramidal cells in the visual cortex of Mecp2-deficient mice, which contributes to silencing neuronal cortical circuits. This phenotype can be rescued independently of Mecp2 by environmental, pharmacological, and genetic manipulation. It remains unknown how Mecp2 mutation can result in abnormal inhibitory circuit refinement. In the present manuscript, we examined the development of GABAergic circuits in the primary visual cortex of Mecp2-deficient mice. We identified that PV circuits were the only GABAergic interneurons to be upregulated, while other interneurons were downregulated. Acceleration of PV cell maturation was accompanied by increased PV cells engulfment by perineuronal nets (PNNs) and by an increase of PV cellular and PNN structural complexity. Interestingly, selective deletion of Mecp2 from PV cells was sufficient to drive increased structure complexity of PNN. Moreover, the accelerated PV and PNN maturation was recapitulated in organotypic cultures. Our results identify a specific timeline of disruption of GABAergic circuits in the absence of Mecp2, indicating a possible cell-autonomous role of MeCP2 in the formation of PV cellular arbors and PNN structures in the visual cortex.
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Affiliation(s)
- Annarita Patrizi
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Schaller Research Group Leader at the German Cancer Research Center (DKFZ), Heildeberg, Germany
| | - Patricia N Awad
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Chloe Li
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Graziella Di Cristo
- Department of Neurosciences, Université de Montréal, Montreal, Canada.,CHU Ste Justine Research Center, Montreal, QC Canada
| | - Michela Fagiolini
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,International Research Center for Neurointelligence, University of Tokyo Institutes for Advanced Study, Tokyo, Japan
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7
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Gomes AR, Fernandes TG, Vaz SH, Silva TP, Bekman EP, Xapelli S, Duarte S, Ghazvini M, Gribnau J, Muotri AR, Trujillo CA, Sebastião AM, Cabral JMS, Diogo MM. Modeling Rett Syndrome With Human Patient-Specific Forebrain Organoids. Front Cell Dev Biol 2020; 8:610427. [PMID: 33363173 PMCID: PMC7758289 DOI: 10.3389/fcell.2020.610427] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 11/23/2020] [Indexed: 12/17/2022] Open
Abstract
Engineering brain organoids from human induced pluripotent stem cells (hiPSCs) is a powerful tool for modeling brain development and neurological disorders. Rett syndrome (RTT), a rare neurodevelopmental disorder, can greatly benefit from this technology, since it affects multiple neuronal subtypes in forebrain sub-regions. We have established dorsal and ventral forebrain organoids from control and RTT patient-specific hiPSCs recapitulating 3D organization and functional network complexity. Our data revealed a premature development of the deep-cortical layer, associated to the formation of TBR1 and CTIP2 neurons, and a lower expression of neural progenitor/proliferative cells in female RTT dorsal organoids. Moreover, calcium imaging and electrophysiology analysis demonstrated functional defects of RTT neurons. Additionally, assembly of RTT dorsal and ventral organoids revealed impairments of interneuron’s migration. Overall, our models provide a better understanding of RTT during early stages of neural development, demonstrating a great potential for personalized diagnosis and drug screening.
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Affiliation(s)
- Ana Rita Gomes
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Tiago G Fernandes
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Sandra H Vaz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Teresa P Silva
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Evguenia P Bekman
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,The Discoveries Centre for Regenerative and Precision Medicine (Lisbon Campus), Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Sara Xapelli
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Sofia Duarte
- Department of Pediatric Neurology, Centro Hospitalar Universitário de Lisboa Central, Lisbon, Portugal
| | - Mehrnaz Ghazvini
- Erasmus MC iPS Facility, Erasmus Medical Center, University Medical Center, Rotterdam, Netherlands
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus Medical Center, University Medical Center, Rotterdam, Netherlands
| | - Alysson R Muotri
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Rady Children's Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, CA, United States.,Center for Academic Research and Training in Anthropogeny, La Jolla, CA, United States
| | - Cleber A Trujillo
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Rady Children's Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, United States.,Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Ana M Sebastião
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Joaquim M S Cabral
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Maria Margarida Diogo
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
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8
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Fagiolini M, Patrizi A, LeBlanc J, Jin LW, Maezawa I, Sinnett S, Gray SJ, Molholm S, Foxe JJ, Johnston MV, Naidu S, Blue M, Hossain A, Kadam S, Zhao X, Chang Q, Zhou Z, Zoghbi H. Intellectual and Developmental Disabilities Research Centers: A Multidisciplinary Approach to Understand the Pathogenesis of Methyl-CpG Binding Protein 2-related Disorders. Neuroscience 2020; 445:190-206. [PMID: 32360592 DOI: 10.1016/j.neuroscience.2020.04.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 12/20/2022]
Abstract
Disruptions in the gene encoding methyl-CpG binding protein 2 (MECP2) underlie complex neurodevelopmental disorders including Rett Syndrome (RTT), MECP2 duplication disorder, intellectual disabilities, and autism. Significant progress has been made on the molecular and cellular basis of MECP2-related disorders providing a new framework for understanding how altered epigenetic landscape can derail the formation and refinement of neuronal circuits in early postnatal life and proper neurological function. This review will summarize selected major findings from the past years and particularly highlight the integrated and multidisciplinary work done at eight NIH-funded Intellectual and Developmental Disabilities Research Centers (IDDRC) across the US. Finally, we will outline a path forward with identification of reliable biomarkers and outcome measures, longitudinal preclinical and clinical studies, reproducibility of results across centers as a synergistic effort to decode and treat the pathogenesis of the complex MeCP2 disorders.
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Affiliation(s)
- Michela Fagiolini
- Children's Hospital Intellectual and Developmental Disabilities Research Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Annarita Patrizi
- Children's Hospital Intellectual and Developmental Disabilities Research Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jocelyn LeBlanc
- Children's Hospital Intellectual and Developmental Disabilities Research Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Lee-Way Jin
- UC Davis MIND Institute, University of California, Sacramento, CA, USA
| | - Izumi Maezawa
- UC Davis MIND Institute, University of California, Sacramento, CA, USA
| | - Sarah Sinnett
- UNC Intellectual and Developmental Disabilities Research Center, University of North Carolina, Gene Therapy Center and Dept. of Ophthalmology, Chapel Hill, NC, USA; Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Steven J Gray
- UNC Intellectual and Developmental Disabilities Research Center, University of North Carolina, Gene Therapy Center and Dept. of Ophthalmology, Chapel Hill, NC, USA; Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sophie Molholm
- The Cognitive Neurophysiology Laboratory, Departments of Pediatrics, Neuroscience, and Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, NY, USA
| | - John J Foxe
- The Cognitive Neurophysiology Laboratory, Ernest J. Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Michael V Johnston
- Kennedy Krieger Institute Intellectual and Developmental Disabilities Research Center/Hugo Moser Research Institute at Kennedy Krieger and Johns Hopkins School of Medicine, USA
| | - Sakkubai Naidu
- Kennedy Krieger Institute Intellectual and Developmental Disabilities Research Center/Hugo Moser Research Institute at Kennedy Krieger and Johns Hopkins School of Medicine, USA
| | - Mary Blue
- Kennedy Krieger Institute Intellectual and Developmental Disabilities Research Center/Hugo Moser Research Institute at Kennedy Krieger and Johns Hopkins School of Medicine, USA
| | - Ahamed Hossain
- Kennedy Krieger Institute Intellectual and Developmental Disabilities Research Center/Hugo Moser Research Institute at Kennedy Krieger and Johns Hopkins School of Medicine, USA
| | - Shilpa Kadam
- Kennedy Krieger Institute Intellectual and Developmental Disabilities Research Center/Hugo Moser Research Institute at Kennedy Krieger and Johns Hopkins School of Medicine, USA
| | - Xinyu Zhao
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Quiang Chang
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Zhaolan Zhou
- Department of Genetic, Epigenetic Institute, University of Pennsylvania Perelman School of Medicine, Intellectual and Developmental Disabilities Research Center, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Huda Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA; Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA
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9
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Di J, Li J, O’Hara B, Alberts I, Xiong L, Li J, Li X. The role of GABAergic neural circuits in the pathogenesis of autism spectrum disorder. Int J Dev Neurosci 2020; 80:73-85. [DOI: 10.1002/jdn.10005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 12/21/2022] Open
Affiliation(s)
- Jing Di
- Department of Neurology David Geffen School of Medicine at UCLA Los Angeles CA USA
| | - Jian Li
- Department of Pediatrics the Second Xiangya HospitalCentral South University Changsha P.R. China
| | - Bruce O’Hara
- Department of Biology University of Kentucky Lexington KY USA
| | - Ian Alberts
- Department of Natural Sciences LaGuardia CCCUNY New York NY USA
| | - Lei Xiong
- Department of Clinical Medicine Yunnan University of Chinese Medicine Kunming P.R. China
| | - Jijun Li
- Department of Integrative Medicine on Pediatrics Shanghai Children’s Medical Center Shanghai Jiao Tong University School of Medicine Shanghai P.R. China
| | - Xiaohong Li
- Department of Neurochemistry New York State Institute for Basic Research in Developmental Disabilities New York NY USA
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10
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Comprehensive Analysis of GABA A-A1R Developmental Alterations in Rett Syndrome: Setting the Focus for Therapeutic Targets in the Time Frame of the Disease. Int J Mol Sci 2020; 21:ijms21020518. [PMID: 31947619 PMCID: PMC7014188 DOI: 10.3390/ijms21020518] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/03/2020] [Accepted: 01/10/2020] [Indexed: 02/08/2023] Open
Abstract
Rett syndrome, a serious neurodevelopmental disorder, has been associated with an altered expression of different synaptic-related proteins and aberrant glutamatergic and γ-aminobutyric acid (GABA)ergic neurotransmission. Despite its severity, it lacks a therapeutic option. Through this work we aimed to define the relationship between MeCP2 and GABAA.-A1 receptor expression, emphasizing the time dependence of such relationship. For this, we analyzed the expression of the ionotropic receptor subunit in different MeCP2 gene-dosage and developmental conditions, in cells lines, and in primary cultured neurons, as well as in different developmental stages of a Rett mouse model. Further, RNAseq and systems biology analysis was performed from post-mortem brain biopsies of Rett patients. We observed that the modulation of the MeCP2 expression in cellular models (both Neuro2a (N2A) cells and primary neuronal cultures) revealed a MeCP2 positive effect on the GABAA.-A1 receptor subunit expression, which did not occur in other proteins such as KCC2 (Potassium-chloride channel, member 5). In the Mecp2+/− mouse brain, both the KCC2 and GABA subunits expression were developmentally regulated, with a decreased expression during the pre-symptomatic stage, while the expression was variable in the adult symptomatic mice. Finally, the expression of the gamma-aminobutyric acid (GABA) receptor-related synaptic proteins from the postmortem brain biopsies of two Rett patients was evaluated, specifically revealing the GABA A1R subunit overexpression. The identification of the molecular changes along with the Rett syndrome prodromic stages strongly endorses the importance of time frame when addressing this disease, supporting the need for a neurotransmission-targeted early therapeutic intervention.
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11
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Li W, Pozzo-Miller L. Dysfunction of the corticostriatal pathway in autism spectrum disorders. J Neurosci Res 2019; 98:2130-2147. [PMID: 31758607 DOI: 10.1002/jnr.24560] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 11/04/2019] [Accepted: 11/05/2019] [Indexed: 12/14/2022]
Abstract
The corticostriatal pathway that carries sensory, motor, and limbic information to the striatum plays a critical role in motor control, action selection, and reward. Dysfunction of this pathway is associated with many neurological and psychiatric disorders. Corticostriatal synapses have unique features in their cortical origins and striatal targets. In this review, we first describe axonal growth and synaptogenesis in the corticostriatal pathway during development, and then summarize the current understanding of the molecular bases of synaptic transmission and plasticity at mature corticostriatal synapses. Genes associated with autism spectrum disorder (ASD) have been implicated in axonal growth abnormalities, imbalance of the synaptic excitation/inhibition ratio, and altered long-term synaptic plasticity in the corticostriatal pathway. Here, we review a number of ASD-associated high-confidence genes, including FMR1, KMT2A, GRIN2B, SCN2A, NLGN1, NLGN3, MET, CNTNAP2, FOXP2, TSHZ3, SHANK3, PTEN, CHD8, MECP2, DYRK1A, RELN, FOXP1, SYNGAP1, and NRXN, and discuss their relevance to proper corticostriatal function.
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Affiliation(s)
- Wei Li
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
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Kadam SD, Sullivan BJ, Goyal A, Blue ME, Smith-Hicks C. Rett Syndrome and CDKL5 Deficiency Disorder: From Bench to Clinic. Int J Mol Sci 2019; 20:ijms20205098. [PMID: 31618813 PMCID: PMC6834180 DOI: 10.3390/ijms20205098] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/08/2019] [Accepted: 10/11/2019] [Indexed: 12/18/2022] Open
Abstract
Rett syndrome (RTT) and CDKL5 deficiency disorder (CDD) are two rare X-linked developmental brain disorders with overlapping but distinct phenotypic features. This review examines the impact of loss of methyl-CpG-binding protein 2 (MeCP2) and cyclin-dependent kinase-like 5 (CDKL5) on clinical phenotype, deficits in synaptic- and circuit-homeostatic mechanisms, seizures, and sleep. In particular, we compare the overlapping and contrasting features between RTT and CDD in clinic and in preclinical studies. Finally, we discuss lessons learned from recent clinical trials while reviewing the findings from pre-clinical studies.
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Affiliation(s)
- Shilpa D Kadam
- The Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Brennan J Sullivan
- The Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA.
| | - Archita Goyal
- The Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA.
| | - Mary E Blue
- The Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Constance Smith-Hicks
- The Hugo Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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13
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Mouro FM, Miranda-Lourenço C, Sebastião AM, Diógenes MJ. From Cannabinoids and Neurosteroids to Statins and the Ketogenic Diet: New Therapeutic Avenues in Rett Syndrome? Front Neurosci 2019; 13:680. [PMID: 31333401 PMCID: PMC6614559 DOI: 10.3389/fnins.2019.00680] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 06/13/2019] [Indexed: 12/21/2022] Open
Abstract
Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused mainly by mutations in the MECP2 gene, being one of the leading causes of mental disability in females. Mutations in the MECP2 gene are responsible for 95% of the diagnosed RTT cases and the mechanisms through which these mutations relate with symptomatology are still elusive. Children with RTT present a period of apparent normal development followed by a rapid regression in speech and behavior and a progressive deterioration of motor abilities. Epilepsy is one of the most common symptoms in RTT, occurring in 60 to 80% of RTT cases, being associated with worsening of other symptoms. At this point, no cure for RTT is available and there is a pressing need for the discovery of new drug candidates to treat its severe symptoms. However, despite being a rare disease, in the last decade research in RTT has grown exponentially. New and exciting evidence has been gathered and the etiopathogenesis of this complex, severe and untreatable disease is slowly being unfolded. Advances in gene editing techniques have prompted cure-oriented research in RTT. Nonetheless, at this point, finding a cure is a distant reality, highlighting the importance of further investigating the basic pathological mechanisms of this disease. In this review, we focus our attention in some of the newest evidence on RTT clinical and preclinical research, evaluating their impact in RTT symptomatology control, and pinpointing possible directions for future research.
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Affiliation(s)
- Francisco Melo Mouro
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Catarina Miranda-Lourenço
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ana Maria Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Maria José Diógenes
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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Auditory sensory memory span for duration is severely curtailed in females with Rett syndrome. Transl Psychiatry 2019; 9:130. [PMID: 30967526 PMCID: PMC6456588 DOI: 10.1038/s41398-019-0463-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 03/23/2019] [Indexed: 11/19/2022] Open
Abstract
Rett syndrome (RTT), a rare neurodevelopmental disorder caused by mutations in the MECP2 gene, is typified by profound cognitive impairment and severe language impairment, rendering it very difficult to accurately measure auditory processing capabilities behaviorally in this population. Here we leverage the mismatch negativity (MMN) component of the event-related potential to measure the ability of RTT patients to decode and store occasional duration deviations in a stream of auditory stimuli. Sensory memory for duration, crucial for speech comprehension, has not been studied in RTT.High-density electroencephalography was successfully recorded in 18 females with RTT and 27 age-matched typically developing (TD) controls (aged 6-22 years). Data from seven RTT and three TD participants were excluded for excessive noise. Stimuli were 1 kHz tones with a standard duration of 100 ms and deviant duration of 180 ms. To assess the sustainability of sensory memory, stimulus presentation rate was varied with stimulus onset asynchronies (SOAs) of 450, 900, and 1800 ms. MMNs with maximum negativity over fronto-central scalp and a latency of 220-230 ms were clearly evident for each presentation rate in the TD group, but only for the shortest SOA in the RTT group. Repeated-measures ANOVA revealed a significant group by SOA interaction. MMN amplitude correlated with age in the TD group only. MMN amplitude was not correlated with the Rett Syndrome Severity Scale. This study indicates that while RTT patients can decode deviations in auditory duration, the span of this sensory memory system is severely foreshortened, with likely implications for speech decoding abilities.
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15
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Brown M, Ashcraft P, Arning E, Bottiglieri T, McClintock W, Giancola F, Lieberman D, Hauser NS, Miller R, Roullet JB, Pearl P, Gibson KM. Rett syndrome (MECP2) and succinic semialdehyde dehydrogenase (ALDH5A1) deficiency in a developmentally delayed female. Mol Genet Genomic Med 2019; 7:e629. [PMID: 30829465 PMCID: PMC6503008 DOI: 10.1002/mgg3.629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/06/2019] [Accepted: 02/10/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND We present a patient with Rett syndrome (RTT; MECP2) and autosomal-recessive succinic semialdehyde dehydrogenase deficiency (SSADHD; ALDH5A1 (aldehyde dehydrogenase 5a1 = SSADH), in whom the current phenotype exhibits features of SSADHD (hypotonia, global developmental delay) and RTT (hand stereotypies, gait anomalies). METHODS γ-Hydroxybutyric acid (GHB) was quantified by UPLC-tandem mass spectrometry, while mutation analysis followed standard methodology of whole-exome sequencing. RESULTS The biochemical hallmark of SSADHD, GHB was increased in the proband's dried bloodspot (DBS; 673 µM; previous SSADHD DBSs (n = 7), range 124-4851 µM); control range (n = 2,831), 0-78 µM. The proband was compound heterozygous for pathogenic ALDH5A1 mutations (p.(Asn418IlefsTer39); maternal; p.(Gly409Asp); paternal) and a de novo RTT nonsense mutation in MECP2 (p.Arg255*). CONCLUSION The major inhibitory neurotransmitter, γ-aminobutyric acid (GABA), is increased in SSADHD but normal in RTT, although there are likely regional changes in GABA receptor distribution. GABAergic anomalies occur in both disorders, each featuring an autism spectrum phenotype. What effect the SSADHD biochemical anomalies (elevated GABA, GHB) might play in the neurodevelopmental/epileptic phenotype of our patient is currently unknown.
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Affiliation(s)
- Madalyn Brown
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Paula Ashcraft
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, Texas
| | - Erland Arning
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, Texas
| | - Teodoro Bottiglieri
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, Texas
| | | | | | - David Lieberman
- Department of Neurology, Boston Children's Hospital, Harvard School of Medicine, Boston, Massachusetts
| | | | | | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Phillip Pearl
- Department of Neurology, Boston Children's Hospital, Harvard School of Medicine, Boston, Massachusetts
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
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16
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Amaddeo A, De Sanctis L, Arroyo JO, Khirani S, Bahi-Buisson N, Fauroux B. Polysomnographic findings in Rett syndrome. Eur J Paediatr Neurol 2019; 23:214-221. [PMID: 30262236 DOI: 10.1016/j.ejpn.2018.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/27/2018] [Accepted: 09/04/2018] [Indexed: 01/15/2023]
Abstract
INTRODUCTION Rett syndrome (RS) is a severe neurodevelopment disorder associated with abnormal breathing during wakefulness and disturbed nocturnal behaviour. Breathing abnormalities during daytime have been extensively reported but polysomnographic (PSG) findings have been poorly studied. MATERIALS AND METHODS Consecutive patients with RS carrying distinct mutations in MECP2 gene, who underwent a PSG between October 2014 and January 2018, were included in the study. Clinical and PSG data were collected. RESULTS Seventeen RS girls, mean age 9.5 ± 2.8 years, were included in the study. Mean total sleep time was 366 ± 102 min. Mean sleep efficiency was reduced (66 ± 19%) with only 3 girls presenting a sleep efficiency above 80%. Wake after sleep onset was increased (33 ± 20%) with an arousal index of 7 ± 6 events/hour. Sleep stages were altered with a normal N1 (2 ± 3%), a decreased N2 (34 ± 20%), an increase of N3 (51 ± 23%) and a decrease of REM sleep (12 ± 9%). Mean apnea hypopnea index (AHI) was increased at 19 ± 37 events/hour, with a predominance of obstructive events. Thirteen patients had an AHI > 1.5 event/hour. Four patients had an obstructive AHI >10 events/hour with one patient having associated tonsillar hypertrophy. Two patients had predominant severe central apneas (central AHI 53 and 132 events/hour) which resolved with noninvasive ventilation and nocturnal oxygen therapy respectively. CONCLUSION Girls with RS have poor sleep quality with alterations in slow wave and REM sleep stages. Obstructive respiratory events are uncommon in patients without adenotonsillar hypertrophy. Central respiratory events are rare. Longitudinal studies should help understanding the natural history of sleep disturbances in RS and their relationship with the neurocognitive decline.
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Affiliation(s)
- Alessandro Amaddeo
- Pediatric Noninvasive Ventilation and Sleep Unit, AP-HP, Hôpital Necker-Enfants Malades, Paris, France; Paris Descartes University, Paris, France; Research Unit INSERM U 955, Team 13, Créteil, France.
| | - Livio De Sanctis
- Pediatric Noninvasive Ventilation and Sleep Unit, AP-HP, Hôpital Necker-Enfants Malades, Paris, France
| | - Jorge Olmo Arroyo
- Pediatric Noninvasive Ventilation and Sleep Unit, AP-HP, Hôpital Necker-Enfants Malades, Paris, France
| | - Sonia Khirani
- Pediatric Noninvasive Ventilation and Sleep Unit, AP-HP, Hôpital Necker-Enfants Malades, Paris, France; ASV Santé, Gennevilliers, France
| | - Nadia Bahi-Buisson
- Paris Descartes University, Paris, France; Pediatric Neurology Departement, AP-HP, Hôpital Necker-Enfants Malades, Paris, France
| | - Brigitte Fauroux
- Pediatric Noninvasive Ventilation and Sleep Unit, AP-HP, Hôpital Necker-Enfants Malades, Paris, France; Paris Descartes University, Paris, France; Research Unit INSERM U 955, Team 13, Créteil, France
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17
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Liao W. Psychomotor Dysfunction in Rett Syndrome: Insights into the Neurochemical and Circuit Roots. Dev Neurobiol 2018; 79:51-59. [PMID: 30430747 DOI: 10.1002/dneu.22651] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 09/29/2018] [Accepted: 10/25/2018] [Indexed: 12/19/2022]
Abstract
Rett syndrome (RTT) is a monogenic neurodevelopmental disorder caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene. Patients with RTT develop symptoms after 6-18 months of age, exhibiting characteristic movement deficits, such as ambulatory difficulties and loss of hand skills, in addition to breathing abnormalities and intellectual disability. Given the striking psychomotor dysfunction, numerous studies have investigated the underlying neurochemical and circuit mechanisms from different aspects. Here, I review the evidence linking MeCP2 deficiency to alterations in neurotransmission and neural circuits that govern the psychomotor function and discuss a recently identified pathological origin underlying the psychomotor deficits in RTT.
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Affiliation(s)
- Wenlin Liao
- Institute of Neuroscience, National Cheng-Chi University, Taipei 11605, Taiwan.,Research Center for Mind, Brain and Learning, National Cheng-Chi University, Taipei 11605, Taiwan
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18
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Prefrontal cortex-dependent innate behaviors are altered by selective knockdown of Gad1 in neuropeptide Y interneurons. PLoS One 2018; 13:e0200809. [PMID: 30024942 PMCID: PMC6053188 DOI: 10.1371/journal.pone.0200809] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 06/09/2018] [Indexed: 12/23/2022] Open
Abstract
GABAergic dysfunction has been implicated in a variety of neurological and psychiatric disorders, including anxiety disorders. Anxiety disorders are the most common type of psychiatric disorder during adolescence. There is a deficiency of GABAergic transmission in anxiety, and enhancement of GABA transmission through pharmacological means reduces anxiety behaviors. GAD67—the enzyme responsible for GABA production–has been linked to anxiety disorders. One class of GABAergic interneurons, Neuropeptide Y (NPY) expressing cells, is abundantly found in brain regions associated with anxiety and fear learning, including prefrontal cortex, hippocampus and amygdala. Additionally, NPY itself has been shown to have anxiolytic effects, and loss of NPY+ interneurons enhances anxiety behaviors. A previous study showed that knockdown of Gad1 from NPY+ cells led to reduced anxiety behaviors in adult mice. However, the role of GABA release from NPY+ interneurons in adolescent anxiety is unclear. Here we used a transgenic mouse that reduces GAD67 in NPY+ cells (NPYGAD1-TG) through Gad1 knockdown and tested for effects on behavior in adolescent mice. Adolescent NPYGAD1-TG mice showed enhanced anxiety-like behavior and sex-dependent changes in locomotor activity. We also found enhancement in two other innate behavioral tasks, nesting construction and social dominance. In contrast, fear learning was unchanged. Because we saw changes in behavioral tasks dependent upon prefrontal cortex and hippocampus, we investigated the extent of GAD67 knockdown in these regions. Immunohistochemistry revealed a 40% decrease in GAD67 in NPY+ cells in prefrontal cortex, indicating a significant but incomplete knockdown of GAD67. In contrast, there was no decrease in GAD67 in NPY+ cells in hippocampus. Consistent with this, there was no change in inhibitory synaptic transmission in hippocampus. Our results show the behavioral impact of cell-specific interneuron dysfunction and suggest that GABA release by NPY+ cells is important for regulating innate prefrontal cortex-dependent behavior in adolescents.
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Are dopamine receptor and transporter changes in Rett syndrome reflected in Mecp2-deficient mice? Exp Neurol 2018; 307:74-81. [PMID: 29782864 DOI: 10.1016/j.expneurol.2018.05.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 04/27/2018] [Accepted: 05/17/2018] [Indexed: 11/20/2022]
Abstract
We tested the claim that the dopaminergic dysfunction of Rett Syndrome (RTT) also occurs in Mecp2-deficient mice that serve as a model of the syndrome. We used positron emission tomography (PET) to image dopamine D2 receptors (D2R) and transporters (DAT) in women with RTT and in Mecp2-deficient mice, and D1R and D2R density was measured in postmortem human tissue by autoradiography. Results showed 1) significantly reduced D2R density in the striatum of women with RTT compared to control subjects. 2) PET imaging of mouse striatum similarly demonstrated significant reductions in D2R density of 7-10 week-old hemizygous (Mecp2-null) and heterozygous (HET) mice compared to wild type (WT) mice. With age, the density of D2R declined in WT mice but not HET mice. 3) In contrast, postmortem autoradiography revealed no group differences in the density of D1R and D2R in the caudate and putamen of RTT versus normal control subjects. 4) In humans and in the mouse model, PET revealed only marginal group differences in DAT. The results confirm that dopaminergic dysfunction in RTT is also present in Mecp2-deficient mice and that reductions in D2R more likely explain the impaired ambulation and progressive rigidity observed rather than alterations in DAT.
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20
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Nance E, Kambhampati SP, Smith ES, Zhang Z, Zhang F, Singh S, Johnston MV, Kannan RM, Blue ME, Kannan S. Dendrimer-mediated delivery of N-acetyl cysteine to microglia in a mouse model of Rett syndrome. J Neuroinflammation 2017; 14:252. [PMID: 29258545 PMCID: PMC5735803 DOI: 10.1186/s12974-017-1004-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 11/15/2017] [Indexed: 01/06/2023] Open
Abstract
Background Rett syndrome (RTT) is a pervasive developmental disorder that is progressive and has no effective cure. Immune dysregulation, oxidative stress, and excess glutamate in the brain mediated by glial dysfunction have been implicated in the pathogenesis and worsening of symptoms of RTT. In this study, we investigated a new nanotherapeutic approach to target glia for attenuation of brain inflammation/injury both in vitro and in vivo using a Mecp2-null mouse model of Rett syndrome. Methods To determine whether inflammation and immune dysregulation were potential targets for dendrimer-based therapeutics in RTT, we assessed the immune response of primary glial cells from Mecp2-null and wild-type (WT) mice to LPS. Using dendrimers that intrinsically target activated microglia and astrocytes, we studied N-acetyl cysteine (NAC) and dendrimer-conjugated N-acetyl cysteine (D-NAC) effects on inflammatory cytokines by PCR and multiplex assay in WT vs Mecp2-null glia. Since the cysteine-glutamate antiporter (Xc−) is upregulated in Mecp2-null glia when compared to WT, the role of Xc− in the uptake of NAC and l-cysteine into the cell was compared to that of D-NAC using BV2 cells in vitro. We then assessed the ability of D-NAC given systemically twice weekly to Mecp2-null mice to improve behavioral phenotype and lifespan. Results We demonstrated that the mixed glia derived from Mecp2-null mice have an exaggerated inflammatory and oxidative stress response to LPS stimulation when compared to WT glia. Expression of Xc− was significantly upregulated in the Mecp2-null glia when compared to WT and was further increased in the presence of LPS stimulation. Unlike NAC, D-NAC bypasses the Xc− for cell uptake, increasing intracellular GSH levels while preventing extracellular glutamate release and excitotoxicity. Systemically administered dendrimers were localized in microglia in Mecp2-null mice, but not in age-matched WT littermates. Treatment with D-NAC significantly improved behavioral outcomes in Mecp2-null mice, but not survival. Conclusions These results suggest that delivery of drugs using dendrimer nanodevices offers a potential strategy for targeting glia and modulating oxidative stress and immune responses in RTT. Electronic supplementary material The online version of this article (10.1186/s12974-017-1004-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elizabeth Nance
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA.,Present address: Department of Chemical Engineering, University of Washington, Seattle, WA, 98105, USA
| | - Siva P Kambhampati
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA
| | - Elizabeth S Smith
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Zhi Zhang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Fan Zhang
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA.,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Sarabdeep Singh
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Michael V Johnston
- Hugo W. Moser Research Institute, Kennedy Krieger, Inc., Baltimore, MD, 21205, USA
| | - Rangaramanujam M Kannan
- Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA.,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.,Hugo W. Moser Research Institute, Kennedy Krieger, Inc., Baltimore, MD, 21205, USA
| | - Mary E Blue
- Hugo W. Moser Research Institute, Kennedy Krieger, Inc., Baltimore, MD, 21205, USA.
| | - Sujatha Kannan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. .,Center for Nanomedicine, Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA. .,Hugo W. Moser Research Institute, Kennedy Krieger, Inc., Baltimore, MD, 21205, USA.
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GABA A receptor subunit deregulation in the hippocampus of human foetuses with Down syndrome. Brain Struct Funct 2017; 223:1501-1518. [PMID: 29168008 PMCID: PMC5869939 DOI: 10.1007/s00429-017-1563-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 11/05/2017] [Indexed: 11/01/2022]
Abstract
The function, regulation and cellular distribution of GABAA receptor subunits have been extensively documented in the adult rodent brain and are linked to numerous neurological disorders. However, there is a surprising lack of knowledge on the cellular (sub-) distribution of GABAA receptor subunits and of their expressional regulation in developing healthy and diseased foetal human brains. To propose a role for GABAA receptor subunits in neurodevelopmental disorders, we studied the developing hippocampus of normal and Down syndrome foetuses. Among the α1-3 and γ2 subunits probed, we find significantly altered expression profiles of the α1, α3 and γ2 subunits in developing Down syndrome hippocampi, with the α3 subunit being most affected. α3 subunits were selectively down-regulated in all hippocampal subfields and developmental periods tested in Down syndrome foetuses, presenting a developmental mismatch by their adult-like distribution in early foetal development. We hypothesized that increased levels of the amyloid precursor protein (APP), and particularly its neurotoxic β-amyloid (1-42) fragment, could disrupt α3 gene expression, likely by facilitating premature neuronal differentiation. Indeed, we find increased APP content in the hippocampi of the Down foetuses. In a corresponding cellular model, soluble β-amyloid (1-42) administered to cultured SH-SY5Y neuroblastoma cells, augmented by retinoic acid-induced differentiation towards a neuronal phenotype, displayed a reduction in α3 subunit levels. In sum, this study charts a comprehensive regional and subcellular map of key GABAA receptor subunits in identified neuronal populations in the hippocampus of healthy and Down syndrome foetuses and associates increased β-amyloid load with discordant down-regulation of α3 subunits.
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22
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Na ES, De Jesús-Cortés H, Martinez-Rivera A, Kabir ZD, Wang J, Ramesh V, Onder Y, Rajadhyaksha AM, Monteggia LM, Pieper AA. D-cycloserine improves synaptic transmission in an animal model of Rett syndrome. PLoS One 2017; 12:e0183026. [PMID: 28813484 PMCID: PMC5559075 DOI: 10.1371/journal.pone.0183026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/30/2017] [Indexed: 01/24/2023] Open
Abstract
Rett syndrome (RTT), a leading cause of intellectual disability in girls, is predominantly caused by mutations in the X-linked gene MECP2. Disruption of Mecp2 in mice recapitulates major features of RTT, including neurobehavioral abnormalities, which can be reversed by re-expression of normal Mecp2. Thus, there is reason to believe that RTT could be amenable to therapeutic intervention throughout the lifespan of patients after the onset of symptoms. A common feature underlying neuropsychiatric disorders, including RTT, is altered synaptic function in the brain. Here, we show that Mecp2tm1.1Jae/y mice display lower presynaptic function as assessed by paired pulse ratio, as well as decreased long term potentiation (LTP) at hippocampal Schaffer–collateral-CA1 synapses. Treatment of Mecp2tm1.1Jae/y mice with D-cycloserine (DCS), an FDA-approved analog of the amino acid D-alanine with antibiotic and glycinergic activity, corrected the presynaptic but not LTP deficit without affecting deficient hippocampal BDNF levels. DCS treatment did, however, partially restore lower BDNF levels in the brain stem and striatum. Thus, treatment with DCS may mitigate the severity of some of the neurobehavioral symptoms experienced by patients with Rett syndrome.
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Affiliation(s)
- Elisa S. Na
- Department of Psychology & Philosophy, Texas Woman’s University, Denton, TX, United States of America
| | - Héctor De Jesús-Cortés
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Arlene Martinez-Rivera
- Division of Pediatric Neurology, Department of Pediatrics, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
| | - Zeeba D. Kabir
- Division of Pediatric Neurology, Department of Pediatrics, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
| | - Jieqi Wang
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
| | - Vijayashree Ramesh
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, United States of America
| | - Yasemin Onder
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, United States of America
| | - Anjali M. Rajadhyaksha
- Division of Pediatric Neurology, Department of Pediatrics, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- * E-mail: (AMR); (LMM); (AAP)
| | - Lisa M. Monteggia
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, United States of America
- * E-mail: (AMR); (LMM); (AAP)
| | - Andrew A. Pieper
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Department of Free Radical and Radiation Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Department of Veterans Affairs, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Pappajohn Biomedical Institute, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- * E-mail: (AMR); (LMM); (AAP)
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Nomura J, Kannan G, Takumi T. Rodent models of genetic and chromosomal variations in psychiatric disorders. Psychiatry Clin Neurosci 2017; 71:508-517. [PMID: 28317218 DOI: 10.1111/pcn.12524] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/02/2017] [Accepted: 03/14/2017] [Indexed: 12/13/2022]
Abstract
Elucidating the molecular basis of complex human psychiatric disorders is challenging due to the multitude of factors that underpin these disorders. Genetic and chromosomal changes are two factors that have been suggested to be involved in psychiatric disorders. Indeed, numerous risk loci have been identified in autism spectrum disorders, schizophrenia, and related psychiatric disorders. Here, we introduce genetic animal models that disturb excitatory-inhibitory balance in the brain and animal models mirroring human chromosomal abnormalities, both of which may be implicated in autism spectrum disorder pathophysiology. In addition, we discuss recent unique translational research using rodent models, such as Cntnap2 knockout mouse, Mecp2 mutant mouse, Pick1 knockout mouse, and neonatal ventral hippocampal lesion rat. By using these models, several types of drugs are administered during the developmental period to see the effect on psychotic symptoms and neural activities in adults. The accumulating evidence from recent animal studies provides an informative intervention strategy as a translational research.
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Affiliation(s)
- Jun Nomura
- RIKEN Brain Science Institute, Saitama, Japan
| | - Geetha Kannan
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, USA
| | - Toru Takumi
- RIKEN Brain Science Institute, Saitama, Japan
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Peng J. [MECP2 gene and MECP2-related diseases]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2017; 19:494-497. [PMID: 28506335 PMCID: PMC7389123 DOI: 10.7499/j.issn.1008-8830.2017.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/10/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China
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Chin Wong L, Hung PL, Jan TY, Lee WT. Variations of stereotypies in individuals with Rett syndrome: A nationwide cross-sectional study in Taiwan. Autism Res 2017; 10:1204-1214. [PMID: 28272783 DOI: 10.1002/aur.1774] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 01/18/2017] [Accepted: 02/06/2017] [Indexed: 01/04/2023]
Abstract
Individuals with Rett syndrome (RTT) can have variable manifestations of stereotypies. In this nation-wide cross-sectional study, we recruited all individuals with RTT in Taiwan diagnosed as RTT by neurologists based on genetic findings and diagnostic criteria. The data were collected using questionnaire. A total 43 cases of typical RTT and 15 cases of atypical RTT, aged from 2.1 to 40.1 years, were enrolled. They included 3 (5.2%) in stage II, 42 (72.4%) in stage III, and 13 (22.4%) in stage IV. All individuals presented with at least one stereotypy. Individuals with atypical RTT had more varied stereotypies (mean: 14 ± 6) compared to those with typical RTT (mean: 9 ± 5) (P = 0.003). Flapping (73.3%) and wringing (58.1%) were the most common hand stereotypies in atypical and typical RTT, respectively. Compared with typical RTT, hair pulling, bruxism, retropulsion, and protrusion of lips were more common in atypical RTT (P = 0.003, P = 0.006, P = 0.003 and <0.001, respectively). The number of stereotypies did not differ among different stages, clinical severities, and hand functions. Although there were no age-related changes in stereotypies in atypical RTT, flapping (P = 0.012), clapping (P = 0.044), and mouthing with single hand (P = 0.009) were significantly more prevalent in individuals aged <10 years with typical RTT, and they decreased after 10 years. In conclusion, our study showed that the stereotypical movements varied in typical and atypical RTT, implying the heterogeneous nature of the disease and the pathogenic mechanisms of RTT with atypical features. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1204-1214. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.
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Affiliation(s)
- Lee Chin Wong
- Department of Pediatrics, Min-Sheng General Hospital, Min-Sheng Hospital 168, ChingKuo Road, Taoyuan, 330, Taiwan.,Department of Pediatric Neurology, National Taiwan University Children's Hospital, No8, Chung-Shan South Road, Zhong-Zheng District, Taipei, 100, Taiwan
| | - Pi-Lien Hung
- Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital, No.123,DAPI Road, Niaosng District, Kaohsiung, 83301, Taiwan
| | - Tz-Yun Jan
- Graduate Institute of Brain and Mind Sciences, National Taiwan University, No.1, Sec.1, Ren-Ai Road, Taipei, 100, Taiwan
| | - Wang-Tso Lee
- Department of Pediatric Neurology, National Taiwan University Children's Hospital, No8, Chung-Shan South Road, Zhong-Zheng District, Taipei, 100, Taiwan
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Ismail FY, Fatemi A, Johnston MV. Cerebral plasticity: Windows of opportunity in the developing brain. Eur J Paediatr Neurol 2017; 21:23-48. [PMID: 27567276 DOI: 10.1016/j.ejpn.2016.07.007] [Citation(s) in RCA: 265] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 07/06/2016] [Indexed: 12/31/2022]
Abstract
BACKGROUND Neuroplasticity refers to the inherently dynamic biological capacity of the central nervous system (CNS) to undergo maturation, change structurally and functionally in response to experience and to adapt following injury. This malleability is achieved by modulating subsets of genetic, molecular and cellular mechanisms that influence the dynamics of synaptic connections and neural circuitry formation culminating in gain or loss of behavior or function. Neuroplasticity in the healthy developing brain exhibits a heterochronus cortex-specific developmental profile and is heightened during "critical and sensitive periods" of pre and postnatal brain development that enable the construction and consolidation of experience-dependent structural and functional brain connections. PURPOSE In this review, our primary goal is to highlight the essential role of neuroplasticity in brain development, and to draw attention to the complex relationship between different levels of the developing nervous system that are subjected to plasticity in health and disease. Another goal of this review is to explore the relationship between plasticity responses of the developing brain and how they are influenced by critical and sensitive periods of brain development. Finally, we aim to motivate researchers in the pediatric neuromodulation field to build on the current knowledge of normal and abnormal neuroplasticity, especially synaptic plasticity, and their dependence on "critical or sensitive periods" of neural development to inform the design, timing and sequencing of neuromodulatory interventions in order to enhance and optimize their translational applications in childhood disorders of the brain. METHODS literature review. RESULTS We discuss in details five patterns of neuroplasticity expressed by the developing brain: 1) developmental plasticity which is further classified into normal and impaired developmental plasticity as seen in syndromic autism spectrum disorders, 2) adaptive (experience-dependent) plasticity following intense motor skill training, 3) reactive plasticity to pre and post natal CNS injury or sensory deprivation, 4) excessive plasticity (loss of homeostatic regulation) as seen in dystonia and refractory epilepsy, 6) and finally, plasticity as the brain's "Achilles tendon" which induces brain vulnerability under certain conditions such as hypoxic ischemic encephalopathy and epileptic encephalopathy syndromes. We then explore the unique feature of "time-sensitive heightened plasticity responses" in the developing brain in the in the context of neuromodulation. CONCLUSION The different patterns of neuroplasticity and the unique feature of heightened plasticity during critical and sensitive periods are important concepts for researchers and clinicians in the field of pediatric neurology and neurodevelopmental disabilities. These concepts need to be examined systematically in the context of pediatric neuromodulation. We propose that critical and sensitive periods of brain development in health and disease can create "windows of opportunity" for neuromodulatory interventions that are not commonly seen in adult brain and probably augment plasticity responses and improve clinical outcomes.
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Affiliation(s)
- Fatima Yousif Ismail
- Department of neurology and developmental medicine, The Kennedy Krieger Institute, Johns Hopkins Medical Institutions, MD, USA; Department of pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al- Ain, UAE.
| | - Ali Fatemi
- Departments of Neurology and Pediatrics, The Kennedy Krieger Institute, and Johns Hopkins University School of Medicine, MD, USA
| | - Michael V Johnston
- Departments of Neurology and Pediatrics, The Kennedy Krieger Institute, and Johns Hopkins University School of Medicine, MD, USA
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Janc OA, Hüser MA, Dietrich K, Kempkes B, Menzfeld C, Hülsmann S, Müller M. Systemic Radical Scavenger Treatment of a Mouse Model of Rett Syndrome: Merits and Limitations of the Vitamin E Derivative Trolox. Front Cell Neurosci 2016; 10:266. [PMID: 27895554 PMCID: PMC5109403 DOI: 10.3389/fncel.2016.00266] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 11/01/2016] [Indexed: 12/21/2022] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder typically arising from spontaneous mutations in the X-chromosomal methyl-CpG binding protein 2 (MECP2) gene. The almost exclusively female Rett patients show an apparently normal development during their first 6-18 months of life. Subsequently, cognitive- and motor-impairment, hand stereotypies, loss of learned skills, epilepsy and irregular breathing manifest. Early mitochondrial impairment and oxidative challenge are considered to facilitate disease progression. Along this line, we recently confirmed in vitro that acute treatment with the vitamin E-derivative Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, ameliorates cellular redox balance and improves hypoxia tolerance in male MeCP2-deficient (Mecp2-/y ) mouse hippocampus. Pursuing these promising findings, we performed a preclinical study to define the merit of systemic Trolox administration. Blinded, placebo-controlled in vivo treatment of male mice started at postnatal day (PD) 10-11 and continued for ~40 days. Compounds (vehicle only, 10 mg/kg or 40 mg/kg Trolox) were injected intraperitoneally every 48 h. Detailed phenotyping revealed that in Mecp2-/y mice, blood glucose levels, lipid peroxidation, synaptic short-term plasticity, hypoxia tolerance and certain forms of environmental exploration were improved by Trolox. Yet, body weight and size, motor function and the rate and regularity of breathing did not improve. In conclusion, in vivo Trolox treatment partially ameliorated a subset of symptoms of the complex Rett phenotype, thereby confirming a partial merit of the vitamin E-derivative based pharmacotherapy. Yet, it also became evident that frequent animal handling and the route of drug administration are critical issues to be optimized in future trials.
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Affiliation(s)
- Oliwia A Janc
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany; Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Universitätsmedizin Göttingen, Georg-August-UniversitätGöttingen, Germany
| | - Marc A Hüser
- Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Universitätsmedizin Göttingen, Georg-August-Universität Göttingen, Germany
| | - Katharina Dietrich
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany; Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Universitätsmedizin Göttingen, Georg-August-UniversitätGöttingen, Germany
| | - Belinda Kempkes
- Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Universitätsmedizin Göttingen, Georg-August-Universität Göttingen, Germany
| | - Christiane Menzfeld
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany; Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Universitätsmedizin Göttingen, Georg-August-UniversitätGöttingen, Germany
| | - Swen Hülsmann
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany; Klinik für Anästhesiologie, Universitätsmedizin Göttingen, Georg-August-UniversitätGöttingen, Germany
| | - Michael Müller
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany; Zentrum Physiologie und Pathophysiologie, Institut für Neuro- und Sinnesphysiologie, Universitätsmedizin Göttingen, Georg-August-UniversitätGöttingen, Germany
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Oginsky MF, Cui N, Zhong W, Johnson CM, Jiang C. Hyperexcitability of Mesencephalic Trigeminal Neurons and Reorganization of Ion Channel Expression in a Rett Syndrome Model. J Cell Physiol 2016; 232:1151-1164. [PMID: 27670841 DOI: 10.1002/jcp.25589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 09/06/2016] [Indexed: 12/30/2022]
Abstract
People with Rett syndrome (RTT) have defects in motor function also seen in Mecp2-null mice. Motor function depends on not only central motor commands but also sensory feedback that is vulnerable to changes in excitability of propriosensory neurons. Here we report evidence for hyperexcitability of mesencephalic trigeminal (Me5) neurons in Mecp2-null mice and a novel cellular mechanism for lowering its impact. In in vitro brain slices, the Me5 neurons in both Mecp2-/Y male and symptomatic Mecp2+/- female mice were overly excitable showing increased firing activity in comparison to their wild-type (WT) male and asymptomatic counterparts. In Mecp2-/Y males, Me5 neurons showed a reduced firing threshold. Consistently, the steady-state activation of voltage-gated Na+ currents (INa ) displayed a hyperpolarizing shift in the Mecp2-null neurons with no change in the INa density. This seems to be due to NaV1.1, SCN1B and SCN4B overexpression and NaV1.2 and SCN3B under-expression. In contrast to the hyperexcitability, the sag potential and postinhibitory rebound (PIR) were reduced in Mecp2-null mice. In voltage-clamp, the IH density was deficient by ∼33%, and the steady-state half-activation had a depolarizing shift of ∼10 mV in the Mecp2-null mice. Quantitative PCR analysis indicated that HCN2 was decreased, HCN1 was upregulated with no change in HCN4 in Mecp2-/Y mice compared to WT. Lastly, blocking IH reduced the firing rate much more in WT than in Mecp2-null neurons. These data suggest that the Mecp2 defect causes an increase in Me5 neuronal excitability likely attributable to alterations in INa , meanwhile IH is reduced likely altering neuronal excitability as well. J. Cell. Physiol. 232: 1151-1164, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Max F Oginsky
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - Ningren Cui
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - Weiwei Zhong
- Department of Biology, Georgia State University, Atlanta, Georgia
| | | | - Chun Jiang
- Department of Biology, Georgia State University, Atlanta, Georgia
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Kaufmann WE, Stallworth JL, Everman DB, Skinner SA. Neurobiologically-based treatments in Rett syndrome: opportunities and challenges. Expert Opin Orphan Drugs 2016; 4:1043-1055. [PMID: 28163986 PMCID: PMC5214376 DOI: 10.1080/21678707.2016.1229181] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/23/2016] [Indexed: 12/14/2022]
Abstract
Introduction: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder that primarily affects females, typically resulting in a period of developmental regression in early childhood followed by stabilization and severe chronic cognitive, behavioral, and physical disability. No known treatment exists beyond symptomatic management, and while insights into the genetic cause, pathophysiology, neurobiology, and natural history of RTT have been gained, many challenges remain. Areas covered: Based on a comprehensive survey of the primary literature on RTT, this article describes and comments upon the general and unique features of the disorder, genetic and neurobiological bases of drug development, and the history of clinical trials in RTT, with an emphasis on drug trial design, outcome measures, and implementation. Expert opinion: Neurobiologically based drug trials are the ultimate goal in RTT, and due to the complexity and global nature of the disorder, drugs targeting both general mechanisms (e.g., growth factors) and specific systems (e.g., glutamate modulators) could be effective. Trial design should optimize data on safety and efficacy, but selection of outcome measures with adequate measurement properties, as well as innovative strategies, such as those enhancing synaptic plasticity and use of biomarkers, are essential for progress in RTT and other neurodevelopmental disorders.
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Affiliation(s)
- Walter E Kaufmann
- Center for Translational Research, Greenwood Genetic Center, Greenwood, SC, USA; Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | | | - David B Everman
- Center for Translational Research, Greenwood Genetic Center , Greenwood , SC , USA
| | - Steven A Skinner
- Center for Translational Research, Greenwood Genetic Center , Greenwood , SC , USA
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Choline Ameliorates Disease Phenotypes in Human iPSC Models of Rett Syndrome. Neuromolecular Med 2016; 18:364-77. [PMID: 27379379 DOI: 10.1007/s12017-016-8421-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 06/24/2016] [Indexed: 12/29/2022]
Abstract
Rett syndrome (RTT) is a postnatal neurodevelopmental disorder that primarily affects girls. Mutations in the methyl-CpG-binding protein 2 (MECP2) gene account for approximately 95 % of all RTT cases. To model RTT in vitro, we generated induced pluripotent stem cells (iPSCs) from fibroblasts of two RTT patients with different mutations (MECP2 (R306C) and MECP2 (1155Δ32)) in their MECP2 gene. We found that these iPSCs were capable of differentiating into functional neurons. Compared to control neurons, the RTT iPSC-derived cells had reduced soma size and a decreased amount of synaptic input, evident both as fewer Synapsin 1-positive puncta and a lower frequency of spontaneous excitatory postsynaptic currents. Supplementation of the culture media with choline rescued all of these defects. Choline supplementation may act through changes in the expression of choline acetyltransferase, an important enzyme in cholinergic signaling, and also through alterations in the lipid metabolite profiles of the RTT neurons. Our study elucidates the possible mechanistic pathways for the effect of choline on human RTT cell models, thereby illustrating the potential for using choline as a nutraceutical to treat RTT.
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31
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Patrizi A, Picard N, Simon AJ, Gunner G, Centofante E, Andrews NA, Fagiolini M. Chronic Administration of the N-Methyl-D-Aspartate Receptor Antagonist Ketamine Improves Rett Syndrome Phenotype. Biol Psychiatry 2016; 79:755-764. [PMID: 26410354 PMCID: PMC7410367 DOI: 10.1016/j.biopsych.2015.08.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 08/13/2015] [Accepted: 08/13/2015] [Indexed: 12/26/2022]
Abstract
BACKGROUND Rett syndrome (RTT) is a neurological disorder caused by mutation of the X-linked MECP2 gene, which results in the progressive disruption of excitatory and inhibitory neuronal circuits. To date, there is no effective treatment available for the disorder. Studies conducted in RTT patients and murine models have shown altered expression of N-methyl-D-aspartate receptors (NMDARs). Genetic deletion of the NMDAR subunit, GluN2A, in mice lacking Mecp2 is sufficient to prevent RTT phenotypes, including regression of vision. METHODS We performed a systematic, randomized preclinical trial of chronic administration of low-dose (8 mg/kg, intraperitoneal) ketamine, an NMDAR antagonist, starting either early in development or at the onset of RTT phenotype in Mecp2-null mice. RESULTS Daily exposure to ketamine ameliorated RTT symptoms and extended the life span of treated Mecp2-null mice without adverse side effects. Furthermore, significant improvement was observed in cortical processing and connectivity, which were fully restored to a wild-type level, particularly when treatment was started at the onset of regression. CONCLUSIONS Our findings provide strong evidence that targeting NMDA receptors can be a safe and effective treatment for RTT.
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Affiliation(s)
- Annarita Patrizi
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Nathalie Picard
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Alex Joseph Simon
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Georgia Gunner
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eleonora Centofante
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Nick Arthur Andrews
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Michela Fagiolini
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.
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Excitatory synapses are stronger in the hippocampus of Rett syndrome mice due to altered synaptic trafficking of AMPA-type glutamate receptors. Proc Natl Acad Sci U S A 2016; 113:E1575-84. [PMID: 26929363 DOI: 10.1073/pnas.1517244113] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Deficits in long-term potentiation (LTP) at central excitatory synapses are thought to contribute to cognitive impairments in neurodevelopmental disorders associated with intellectual disability and autism. Using the methyl-CpG-binding protein 2 (Mecp2) knockout (KO) mouse model of Rett syndrome, we show that naïve excitatory synapses onto hippocampal pyramidal neurons of symptomatic mice have all of the hallmarks of potentiated synapses. Stronger Mecp2 KO synapses failed to undergo LTP after either theta-burst afferent stimulation or pairing afferent stimulation with postsynaptic depolarization. On the other hand, basal synaptic strength and LTP were not affected in slices from younger presymptomatic Mecp2 KO mice. Furthermore, spine synapses in pyramidal neurons from symptomatic Mecp2 KO are larger and do not grow in size or incorporate GluA1 subunits after electrical or chemical LTP. Our data suggest that LTP is occluded in Mecp2 KO mice by already potentiated synapses. The higher surface levels of GluA1-containing receptors are consistent with altered expression levels of proteins involved in AMPA receptor trafficking, suggesting previously unidentified targets for therapeutic intervention for Rett syndrome and other MECP2-related disorders.
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Bittolo T, Raminelli CA, Deiana C, Baj G, Vaghi V, Ferrazzo S, Bernareggi A, Tongiorgi E. Pharmacological treatment with mirtazapine rescues cortical atrophy and respiratory deficits in MeCP2 null mice. Sci Rep 2016; 6:19796. [PMID: 26806603 PMCID: PMC4726391 DOI: 10.1038/srep19796] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/14/2015] [Indexed: 01/22/2023] Open
Abstract
Loss of MeCP2 (Methyl CpG binding protein 2) in Rett syndrome (RTT) causes brain weight decrease, shrinkage of the cortex with reduced dendritic arborization, behavioral abnormalities, seizures and cardio-respiratory complications. The observed monoamine neurotransmitters reduction in RTT suggested antidepressants as a possible therapy. We treated MeCP2-null mice from postnatal-day 28 for two weeks with desipramine, already tested in RTT, or mirtazapine, an antidepressant with limited side-effects, known to promote GABA release. Mirtazapine was more effective than desipramine in restoring somatosensory cortex thickness by fully rescuing pyramidal neurons dendritic arborization and spine density. Functionally, mirtazapine treatment normalized heart rate, breath rate, anxiety levels, and eliminated the hopping behavior observed in MeCP2-null mice, leading to improved phenotypic score. These morphological and functional effects of mirtazapine were accompanied by reestablishment of the GABAergic and glutamatergic receptor activity recorded in cortex and brainstem tissues. Thus, mirtazapine can represent a new potential pharmacological treatment for the Rett syndrome.
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Affiliation(s)
- Tamara Bittolo
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Carlo Antonio Raminelli
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Chiara Deiana
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Gabriele Baj
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Valentina Vaghi
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Sara Ferrazzo
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Annalisa Bernareggi
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
| | - Enrico Tongiorgi
- Department of Life Sciences, University of Trieste, Via L. Giorgieri, 5-34127 Trieste, Italy
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Abstract
Rett syndrome is an extremely disabling X-linked nervous system disorder that mainly affects girls in early childhood and causes autism-like behavior, severe intellectual disability, seizures, sleep disturbances, autonomic instability, and other disorders due to mutations in the MeCP2 (methyl CpG-binding protein 2) transcription factor. The disorder targets synapses and synaptic plasticity and has been shown to disrupt the balance between glutamate excitatory synapses and GABAergic inhibitory synapses. In fact, it can be argued that Rett syndrome is primarily a disorder of synaptic plasticity and that agents that can correct this imbalance may have beneficial effects on brain development. This review briefly summarizes the link between disrupted synaptic plasticity mechanisms and Rett syndrome and early clinical trials that aim to target these abnormalities to improve the outcome for these severely disabled children.
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Affiliation(s)
- Michael Johnston
- Developmental Neuroscience Laboratory, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, USA; Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mary E Blue
- Developmental Neuroscience Laboratory, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sakkubai Naidu
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurogenetics, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Leong WY, Lim ZH, Korzh V, Pietri T, Goh ELK. Methyl-CpG Binding Protein 2 (Mecp2) Regulates Sensory Function Through Sema5b and Robo2. Front Cell Neurosci 2015; 9:481. [PMID: 26733807 PMCID: PMC4685056 DOI: 10.3389/fncel.2015.00481] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/30/2015] [Indexed: 12/31/2022] Open
Abstract
Mutations in the gene encoding the MECP2 underlies Rett syndrome, a neurodevelopmental disorder in young females. Although reduced pain sensitivity in Rett syndrome patients and in partial MeCP2 deficient mice had been reported, these previous studies focused predominantly on motor impairments. Therefore, it is still unknown how MeCP2 is involved in these sensory defects. In addition, the human disease manifestations where males with mutations in MECP2 gene normally do not survive and females show typical neurological symptoms only after 18 months of age, is profoundly different in MeCP2-deficient mouse where all animals survived, and males but not females displayed Rett syndrome phenotypes at an early age. Thus, the mecp2-deficient zebrafish serves as an additional animal model to aid in deciphering the role and mechanisms of Mecp2 in neurodevelopment. Here, we used two independent methods of silencing expression of Mecp2 in zebrafish to uncover a novel role of Mecp2 in trigeminal ganglion sensory neurons during the embryonic development. mecp2-null mutation and morpholino-mediated silencing of Mecp2 in the zebrafish embryos resulted in defects in peripheral innervation of trigeminal sensory neurons and consequently affecting the sensory function. These defects were demonstrated to be dependent on the expression of Sema5b and Robo2. The expression of both proteins together could better overcome the defects caused by Mecp2 deficiency as compared to the expression of either Sema5b or Robo2 alone. Sema5b and Robo2 were downregulated upon Mecp2 silencing or in mecp2-null embryos, and Chromatin immunoprecipitation (ChIP) assay using antibody against Mecp2 was able to pull down specific regions of both Sema5b and Robo2 promoters, showing interaction between Mecp2 and the promoters of both genes. In addition, cell-specific expression of Mecp2 can overcome the innervation and sensory response defects in Mecp2 morphants indicating that these MeCP2-mediated defects are cell-autonomous. The sensory deficits caused by Mecp2 deficiency mirror the diminished sensory response observed in Rett syndrome patients. This suggests that zebrafish could be an unconventional but useful model for this disorder manifesting defects that are not easily studied in full using rodent models.
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Affiliation(s)
- Wan Y Leong
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School, Singapore Singapore
| | - Zhi H Lim
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School, Singapore Singapore
| | - Vladimir Korzh
- Institute of Molecular and Cell Biology, SingaporeSingapore; Department of Biological Sciences, National University of Singapore, SingaporeSingapore
| | - Thomas Pietri
- Institut de Biologie de l'École Normale Supérieure, Institut National de la Santé et de la Recherche Médicale U1024, Centre National de la Recherche Scientifique UMR 8197 Paris, France
| | - Eyleen L K Goh
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School, SingaporeSingapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, SingaporeSingapore; KK Research Centre, KK Women's and Children's Hospital, SingaporeSingapore
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Gao R, Penzes P. Common mechanisms of excitatory and inhibitory imbalance in schizophrenia and autism spectrum disorders. Curr Mol Med 2015; 15:146-67. [PMID: 25732149 DOI: 10.2174/1566524015666150303003028] [Citation(s) in RCA: 321] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 12/20/2014] [Accepted: 01/18/2015] [Indexed: 12/16/2022]
Abstract
Autism Spectrum Disorders (ASD) and Schizophrenia (SCZ) are cognitive disorders with complex genetic architectures but overlapping behavioral phenotypes, which suggests common pathway perturbations. Multiple lines of evidence implicate imbalances in excitatory and inhibitory activity (E/I imbalance) as a shared pathophysiological mechanism. Thus, understanding the molecular underpinnings of E/I imbalance may provide essential insight into the etiology of these disorders and may uncover novel targets for future drug discovery. Here, we review key genetic, physiological, neuropathological, functional, and pathway studies that suggest alterations to excitatory/inhibitory circuits are keys to ASD and SCZ pathogenesis.
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Affiliation(s)
| | - P Penzes
- Department of Physiology, Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611, USA.
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Lo FS, Blue ME, Erzurumlu RS. Enhancement of postsynaptic GABAA and extrasynaptic NMDA receptor-mediated responses in the barrel cortex of Mecp2-null mice. J Neurophysiol 2015; 115:1298-306. [PMID: 26683074 DOI: 10.1152/jn.00944.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/15/2015] [Indexed: 12/12/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder that results from mutations in the X-linked gene for methyl-CpG-binding protein 2 (MECP2). The underlying cellular mechanism for the sensory deficits in patients with RTT is largely unknown. This study used the Bird mouse model of RTT to investigate sensory thalamocortical synaptic transmission in the barrel cortex of Mecp2-null mice. Electrophysiological results showed an excitation/inhibition imbalance, biased toward inhibition, due to an increase in efficacy of postsynaptic GABAA receptors rather than alterations in inhibitory network and presynaptic release properties. Enhanced inhibition impaired the transmission of tonic sensory signals from the thalamus to the somatosensory cortex. Previous morphological studies showed an upregulation of NMDA receptors in the neocortex of both RTT patients and Mecp2-null mice at early ages [Blue ME, Naidu S, Johnston MV. Ann Neurol 45: 541-545, 1999; Blue ME, Kaufmann WE, Bressler J, Eyring C, O'Driscoll C, Naidu S, Johnston MV. Anat Rec (Hoboken) 294: 1624-1634, 2011]. Although AMPA and NMDA receptor-mediated excitatory synaptic transmission was not altered in the barrel cortex of Mecp2-null mice, extrasynaptic NMDA receptor-mediated responses increased markedly. These responses were blocked by memantine, suggesting that extrasynaptic NMDA receptors play an important role in the pathogenesis of RTT. The results suggest that enhancement of postsynaptic GABAA and extrasynaptic NMDA receptor-mediated responses may underlie impaired somatosensation and that pharmacological blockade of extrasynaptic NMDA receptors may have therapeutic value for RTT.
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Affiliation(s)
- Fu-Sun Lo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Mary E Blue
- Hugo W. Moser Research Institute at Kennedy Krieger, Inc. and Departments of Neurology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Reha S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland; and
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Abdala AP, Toward MA, Dutschmann M, Bissonnette JM, Paton JFR. Deficiency of GABAergic synaptic inhibition in the Kölliker-Fuse area underlies respiratory dysrhythmia in a mouse model of Rett syndrome. J Physiol 2015; 594:223-37. [PMID: 26507912 DOI: 10.1113/jp270966] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/23/2015] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Life threatening breathing irregularity and central apnoeas are highly prevalent in children suffering from Rett syndrome. Abnormalities in inhibitory synaptic transmission have been associated with the physiopathology of this syndrome, and may underlie the respiratory disorder. In a mouse model of Rett syndrome, GABAergic terminal projections are markedly reduced in the Kölliker-Fuse nucleus (KF) in the dorsolateral pons, an important centre for control of respiratory rhythm regularity. Administration of a drug that augments endogenous GABA localized to this region of the pons reduced the incidence of apnoea and the respiratory irregularity of Rett female mice. Conversely, the respiratory disorder was recapitulated by blocking GABAergic transmission in the KF area of healthy rats. This study helps us understand the mechanism for generation of respiratory abnormality in Rett syndrome, pinpoints a brain site responsible and provides a clear anatomical target for the development of a translatable drug treatment. Central apnoeas and respiratory irregularity are a common feature in Rett syndrome (RTT), a neurodevelopmental disorder most often caused by mutations in the methyl-CpG-binding protein 2 gene (MECP2). We used a MECP2 deficient mouse model of RTT as a strategy to obtain insights into the neurobiology of the disease and into mechanisms essential for respiratory rhythmicity during normal breathing. Previously, we showed that, systemic administration of a GABA reuptake blocker in MECP2 deficient mice markedly reduced the occurrence of central apnoeas. Further, we found that, during central apnoeas, post-inspiratory drive (adductor motor) to the upper airways was enhanced in amplitude and duration in Mecp2 heterozygous female mice. Since the pontine Kölliker-Fuse area (KF) drives post-inspiration, suppresses inspiration, and can reset the respiratory oscillator phase, we hypothesized that synaptic inhibition in this area is essential for respiratory rhythm regularity. In this study, we found that: (i) Mecp2 heterozygous mice showed deficiency of GABA perisomatic bouton-like puncta and processes in the KF nucleus; (ii) blockade of GABA reuptake in the KF of RTT mice reduced breathing irregularity; (iii) conversely, blockade of GABAA receptors in the KF of healthy rats mimicked the RTT respiratory phenotype of recurrent central apnoeas and prolonged post-inspiratory activity. Our results show that reductions in synaptic inhibition within the KF induce rhythm irregularity whereas boosting GABA transmission reduces respiratory arrhythmia in a murine model of RTT. Our data suggest that manipulation of synaptic inhibition in KF may be a clinically important strategy for alleviating the life threatening respiratory disorders in RTT.
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Affiliation(s)
- Ana Paula Abdala
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Marie A Toward
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia
| | - John M Bissonnette
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Julian F R Paton
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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Ammanuel S, Chan WC, Adler DA, Lakshamanan BM, Gupta SS, Ewen JB, Johnston MV, Marcus CL, Naidu S, Kadam SD. Heightened Delta Power during Slow-Wave-Sleep in Patients with Rett Syndrome Associated with Poor Sleep Efficiency. PLoS One 2015; 10:e0138113. [PMID: 26444000 PMCID: PMC4596813 DOI: 10.1371/journal.pone.0138113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/25/2015] [Indexed: 12/31/2022] Open
Abstract
Sleep problems are commonly reported in Rett syndrome (RTT); however the electroencephalographic (EEG) biomarkers underlying sleep dysfunction are poorly understood. The aim of this study was to analyze the temporal evolution of quantitative EEG (qEEG) biomarkers in overnight EEGs recorded from girls (2–9 yrs. old) diagnosed with RTT using a non-traditional automated protocol. In this study, EEG spectral analysis identified high delta power cycles representing slow wave sleep (SWS) in 8–9h overnight sleep EEGs from the frontal, central and occipital leads (AP axis), comparing age-matched girls with and without RTT. Automated algorithms quantitated the area under the curve (AUC) within identified SWS cycles for each spectral frequency wave form. Both age-matched RTT and control EEGs showed similar increasing trends for recorded delta wave power in the EEG leads along the antero-posterior (AP). RTT EEGs had significantly fewer numbers of SWS sleep cycles; therefore, the overall time spent in SWS was also significantly lower in RTT. In contrast, the AUC for delta power within each SWS cycle was significantly heightened in RTT and remained heightened over consecutive cycles unlike control EEGs that showed an overnight decrement of delta power in consecutive cycles. Gamma wave power associated with these SWS cycles was similar to controls. However, the negative correlation of gamma power with age (r = -.59; p<0.01) detected in controls (2–5 yrs. vs. 6–9 yrs.) was lost in RTT. Poor % SWS (i.e., time spent in SWS overnight) in RTT was also driven by the younger age-group. Incidence of seizures in RTT was associated with significantly lower number of SWS cycles. Therefore, qEEG biomarkers of SWS in RTT evolved temporally and correlated significantly with clinical severity.
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Affiliation(s)
- Simon Ammanuel
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, Maryland, United States of America; Department of Biomedical Engineering, Whiting School of Engineering,Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Wesley C Chan
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, Maryland, United States of America; Department of Biomedical Engineering, Whiting School of Engineering,Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Daniel A Adler
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, Maryland, United States of America; Department of Biomedical Engineering, Whiting School of Engineering,Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Balaji M Lakshamanan
- Department of Neurology and Developmental Medicine, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, Maryland, United States of America
| | - Siddharth S Gupta
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Joshua B Ewen
- Department of Neurology and Developmental Medicine, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, Maryland, United States of America; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Michael V Johnston
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Carole L Marcus
- Sleep Center, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Sakkubai Naidu
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Shilpa D Kadam
- Neuroscience Laboratory, Hugo Moser Research Institute at Kennedy Krieger, Baltimore, Maryland, United States of America; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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Abstract
Intellectual disability, autism spectrum disorder, and epilepsy are prime examples of neurodevelopmental disorders that collectively affect a significant percentage of the world population. Recent technological breakthroughs allowed the elucidation of the genetic causes of many of these disorders. As neurodevelopmental disorders are genetically heterogeneous, the development of rational therapy is extremely challenging. Fortunately, many causative genes are interconnected and cluster in specific cellular pathways. Targeting a common node in such a network would allow us to interfere with a series of related neurodevelopmental disorders at once. Here, we argue that the GABAergic system is disturbed in many neurodevelopmental disorders, including fragile X syndrome, Rett syndrome, and Dravet syndrome, and is a key candidate target for therapeutic intervention. Many drugs that modulate the GABAergic system have already been tested in animal models with encouraging outcomes and are readily available for clinical trials.
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Affiliation(s)
- Sien Braat
- Department of Medical Genetics, University of Antwerp, Prins Boudewijnlaan 43, 2650 Edegem, Belgium
| | - R Frank Kooy
- Department of Medical Genetics, University of Antwerp, Prins Boudewijnlaan 43, 2650 Edegem, Belgium.
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Deficient Purposeful Use of Forepaws in Female Mice Modelling Rett Syndrome. Neural Plast 2015; 2015:326184. [PMID: 26185689 PMCID: PMC4491574 DOI: 10.1155/2015/326184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/21/2015] [Accepted: 05/24/2015] [Indexed: 12/31/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder, characterized by severe behavioural and physiological symptoms. Mutations in the methyl CpG binding protein 2 gene (MECP2) cause more than 95% of classic cases. Motor abnormalities represent a significant part of the spectrum of RTT symptoms. In the present study we investigated motor coordination and fine motor skill domains in MeCP2-308 female mice, a validated RTT model. This was complemented by the in vivo magnetic resonance spectroscopy (MRS) analysis of metabolic profile in behaviourally relevant brain areas. MeCP2-308 heterozygous female mice (Het, 10-12 months of age) were impaired in tasks validated for the assessment of purposeful and coordinated forepaw use (Morag test and Capellini handling task). A fine-grain analysis of spontaneous behaviour in the home-cage also revealed an abnormal handling pattern when interacting with the nesting material, reduced motivation to explore the environment, and increased time devoted to feeding in Het mice. The brain MRS evaluation highlighted decreased levels of bioenergetic metabolites in the striatal area in Het mice compared to controls. Present results confirm behavioural and brain alterations previously reported in MeCP2-308 males and identify novel endpoints on which the efficacy of innovative therapeutic strategies for RTT may be tested.
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42
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MeCP2 in the rostral striatum maintains local dopamine content critical for psychomotor control. J Neurosci 2015; 35:6209-20. [PMID: 25878291 DOI: 10.1523/jneurosci.4624-14.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Methyl-CpG binding protein 2 (MeCP2) is a chromatin regulator highly expressed in mature neurons. Mutations of MECP2 gene cause >90% cases of Rett syndrome, a neurodevelopmental disorder featured by striking psychomotor dysfunction. In Mecp2-null mice, the motor deficits are associated with reduction of dopamine content in the striatum, the input nucleus of basal ganglia mostly composed of GABAergic neurons. Here we investigated the causal role of MeCP2 in modulation of striatal dopamine content and psychomotor function. We found that mice with selective removal of MeCP2 in forebrain GABAergic neurons, predominantly in the striatum, phenocopied Mecp2-null mice in dopamine deregulation and motor dysfunction. Selective expression of MeCP2 in the striatum preserved dopamine content and psychomotor function in both males and females. Notably, the dopamine deregulation was primarily confined to the rostral striatum, and focal deletion or reactivation of MeCP2 expression in the rostral striatum through adeno-associated virus effectively disrupted or restored dopamine content and locomotor activity, respectively. Together, these findings demonstrate that striatal MeCP2 maintains local dopamine content in a non-cell autonomous manner in the rostral striatum and that is critical for psychomotor control.
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Zhong W, Cui N, Jin X, Oginsky MF, Wu Y, Zhang S, Bondy B, Johnson CM, Jiang C. Methyl CpG Binding Protein 2 Gene Disruption Augments Tonic Currents of γ-Aminobutyric Acid Receptors in Locus Coeruleus Neurons: IMPACT ON NEURONAL EXCITABILITY AND BREATHING. J Biol Chem 2015; 290:18400-11. [PMID: 25979331 DOI: 10.1074/jbc.m115.650465] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Indexed: 12/20/2022] Open
Abstract
People with Rett syndrome and mouse models show autonomic dysfunction involving the brain stem locus coeruleus (LC). Neurons in the LC of Mecp2-null mice are overly excited, likely resulting from a defect in neuronal intrinsic membrane properties and a deficiency in GABA synaptic inhibition. In addition to the synaptic GABA receptors, there is a group of GABAA receptors (GABAARs) that is located extrasynaptically and mediates tonic inhibition. Here we show evidence for augmentation of the extrasynaptic GABAARs in Mecp2-null mice. In brain slices, exposure of LC neurons to GABAAR agonists increased tonic currents that were blocked by GABAAR antagonists. With 10 μm GABA, the bicuculline-sensitive tonic currents were ∼4-fold larger in Mecp2-null LC neurons than in the WT. Single-cell PCR analysis showed that the δ subunit, the principal subunit of extrasynaptic GABAARs, was present in LC neurons. Expression levels of the δ subunit were ∼50% higher in Mecp2-null neurons than in the WT. Also increased in expression in Mecp2-null mice was another extrasynaptic GABAAR subunit, α6, by ∼4-fold. The δ subunit-selective agonists 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol hydrochloride and 4-chloro-N-[2-(2-thienyl)imidazo[1,2-a]pyridin-3-yl]]benzamide activated the tonic GABAA currents in LC neurons and reduced neuronal excitability to a greater degree in Mecp2-null mice than in the WT. Consistent with these findings, in vivo application of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol hydrochloride alleviated breathing abnormalities of conscious Mecp2-null mice. These results suggest that extrasynaptic GABAARs seem to be augmented with Mecp2 disruption, which may be a compensatory response to the deficiency in GABAergic synaptic inhibition and allows control of neuronal excitability and breathing abnormalities.
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Affiliation(s)
- Weiwei Zhong
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | - Ningren Cui
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | - Xin Jin
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | - Max F Oginsky
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | - Yang Wu
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | - Shuang Zhang
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | - Brian Bondy
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
| | | | - Chun Jiang
- From the Department of Biology, Georgia State University, Atlanta, Georgia 30303
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Schmidt MJ, Mirnics K. Neurodevelopment, GABA system dysfunction, and schizophrenia. Neuropsychopharmacology 2015; 40:190-206. [PMID: 24759129 PMCID: PMC4262918 DOI: 10.1038/npp.2014.95] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/03/2014] [Accepted: 04/11/2014] [Indexed: 02/07/2023]
Abstract
The origins of schizophrenia have eluded clinicians and researchers since Kraepelin and Bleuler began documenting their findings. However, large clinical research efforts in recent decades have identified numerous genetic and environmental risk factors for schizophrenia. The combined data strongly support the neurodevelopmental hypothesis of schizophrenia and underscore the importance of the common converging effects of diverse insults. In this review, we discuss the evidence that genetic and environmental risk factors that predispose to schizophrenia disrupt the development and normal functioning of the GABAergic system.
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Affiliation(s)
- Martin J Schmidt
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
| | - Karoly Mirnics
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN, USA
- Department of Psychiatry, University of Szeged, Szeged, Hungary
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MeCP2 Modulates Sex Differences in the Postsynaptic Development of the Valproate Animal Model of Autism. Mol Neurobiol 2014; 53:40-56. [PMID: 25404090 DOI: 10.1007/s12035-014-8987-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 11/04/2014] [Indexed: 01/10/2023]
Abstract
Males are predominantly affected by autism spectrum disorders (ASD) with a prevalence ratio of 5:1. However, the underlying pathological mechanisms governing the male preponderance of ASD remain unclear. Recent studies suggested that epigenetic aberrations may cause synaptic dysfunctions, which might be related to the pathophysiology of ASD. In this study, we used rat offspring prenatally exposed to valproic acid (VPA) as an animal model of ASD. We found male-selective abnormalities in the kinetic profile of the excitatory glutamatergic synaptic protein expressions linked to N-methyl-D-aspartate receptor (NMDAR), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and metabotropic glutamate receptor 5 (mGluR5) pathways in the prefrontal cortex of the VPA-exposed offspring at postnatal weeks 1, 2, and 4. Furthermore, VPA exposure showed a male-specific attenuation of the methyl-CpG-binding protein 2 (MeCP2) expressions both in the prefrontal cortex of offspring and in the gender-isolated neural progenitor cells (NPCs). In the gender-isolated NPCs culture, higher concentration of VPA induced an increased glutamatergic synaptic development along with decreased MeCP2 expression in both genders suggesting the role of MeCP2 in the modulation of synaptic development. In the small interfering RNA (siRNA) knock-down study, 50 pmol of Mecp2 siRNA inhibited the MeCP2 expression in male- but not in female-derived NPCs with concomitant induction of postsynaptic proteins such as PSD95. Taken together, we suggest that the male-inclined reduction of MeCP2 expression is involved in the abnormal development of glutamatergic synapse and male preponderance in the VPA animal models of ASD.
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47
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Weissman J, Naidu S, Bjornsson HT. Abnormalities of the DNA methylation mark and its machinery: an emerging cause of neurologic dysfunction. Semin Neurol 2014; 34:249-57. [PMID: 25192503 PMCID: PMC4512289 DOI: 10.1055/s-0034-1386763] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Recently, Mendelian disorders of the DNA methylation machinery have been described which demonstrate the complex roles of epigenetics in neurodevelopment and disease. For example, defects of DNMT1, the maintenance methyltransferase, lead to adult-onset progressive neurologic disorders, whereas defects of the de novo methyltransferases DNMT3A and DNMT3B lead to nonprogressive neurodevelopmental conditions. Furthermore, patients with DNMT3A deficiency demonstrate overgrowth, a feature common to disorders of histone machinery and imprinting disorders, highlighting the interconnectedness of the many epigenetic layers. Disorders of the DNA methylation machinery include both the aforementioned "writers" and also the "readers" of the methyl mark, such as MeCP2, the cause of Rett syndrome. Any dosage disruption, either haploinsufficiency or overexpression of DNA methylation machinery leads to widespread gene expression changes in trans, disrupting expression of a subset of target genes that contribute to individual disease phenotypes. In contrast, classical imprinting disorders such as Angelman syndrome have been thought generally to cause epigenetic dysregulation in cis. However, the recent description of multilocus methylation disorders challenges this generalization. Here, in addition to summarizing recent developments in identifying the pathogenesis of these diseases, we highlight clinical considerations and some unexpected therapeutic opportunities, such as topoisomerase inhibitors for classical imprinting disorders.
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Affiliation(s)
- Jacqueline Weissman
- Kennedy Krieger Institute, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sakkubai Naidu
- Kennedy Krieger Institute, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hans T. Bjornsson
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
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GluD1 is a common altered player in neuronal differentiation from both MECP2-mutated and CDKL5-mutated iPS cells. Eur J Hum Genet 2014; 23:195-201. [PMID: 24916645 DOI: 10.1038/ejhg.2014.81] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 03/17/2014] [Accepted: 04/04/2014] [Indexed: 12/16/2022] Open
Abstract
Rett syndrome is a monogenic disease due to de novo mutations in either MECP2 or CDKL5 genes. In spite of their involvement in the same disease, a functional interaction between the two genes has not been proven. MeCP2 is a transcriptional regulator; CDKL5 encodes for a kinase protein that might be involved in the regulation of gene expression. Therefore, we hypothesized that mutations affecting the two genes may lead to similar phenotypes by dysregulating the expression of common genes. To test this hypothesis we used induced pluripotent stem (iPS) cells derived from fibroblasts of one Rett patient with a MECP2 mutation (p.Arg306Cys) and two patients with mutations in CDKL5 (p.Gln347Ter and p.Thr288Ile). Expression profiling was performed in CDKL5-mutated cells and genes of interest were confirmed by real-time RT-PCR in both CDKL5- and MECP2-mutated cells. The only major change in gene expression common to MECP2- and CDKL5-mutated cells was for GRID1, encoding for glutamate D1 receptor (GluD1), a member of the δ-family of ionotropic glutamate receptors. GluD1 does not form AMPA or NMDA glutamate receptors. It acts like an adhesion molecule by linking the postsynaptic and presynaptic compartments, preferentially inducing the inhibitory presynaptic differentiation of cortical neurons. Our results demonstrate that GRID1 expression is downregulated in both MECP2- and CDKL5-mutated iPS cells and upregulated in neuronal precursors and mature neurons. These data provide novel insights into disease pathophysiology and identify possible new targets for therapeutic treatment of Rett syndrome.
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Deidda G, Bozarth IF, Cancedda L. Modulation of GABAergic transmission in development and neurodevelopmental disorders: investigating physiology and pathology to gain therapeutic perspectives. Front Cell Neurosci 2014; 8:119. [PMID: 24904277 PMCID: PMC4033255 DOI: 10.3389/fncel.2014.00119] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/14/2014] [Indexed: 01/30/2023] Open
Abstract
During mammalian ontogenesis, the neurotransmitter GABA is a fundamental regulator of neuronal networks. In neuronal development, GABAergic signaling regulates neural proliferation, migration, differentiation, and neuronal-network wiring. In the adult, GABA orchestrates the activity of different neuronal cell-types largely interconnected, by powerfully modulating synaptic activity. GABA exerts these functions by binding to chloride-permeable ionotropic GABAA receptors and metabotropic GABAB receptors. According to its functional importance during development, GABA is implicated in a number of neurodevelopmental disorders such as autism, Fragile X, Rett syndrome, Down syndrome, schizophrenia, Tourette's syndrome and neurofibromatosis. The strength and polarity of GABAergic transmission is continuously modulated during physiological, but also pathological conditions. For GABAergic transmission through GABAA receptors, strength regulation is achieved by different mechanisms such as modulation of GABAA receptors themselves, variation of intracellular chloride concentration, and alteration in GABA metabolism. In the never-ending effort to find possible treatments for GABA-related neurological diseases, of great importance would be modulating GABAergic transmission in a safe and possibly physiological way, without the dangers of either silencing network activity or causing epileptic seizures. In this review, we will discuss the different ways to modulate GABAergic transmission normally at work both during physiological and pathological conditions. Our aim is to highlight new research perspectives for therapeutic treatments that reinstate natural and physiological brain functions in neuro-pathological conditions.
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Affiliation(s)
- Gabriele Deidda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Ignacio F Bozarth
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Laura Cancedda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
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Modulation of behavioral networks by selective interneuronal inactivation. Mol Psychiatry 2014; 19:580-7. [PMID: 24322205 PMCID: PMC4179403 DOI: 10.1038/mp.2013.167] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/04/2013] [Accepted: 10/17/2013] [Indexed: 12/15/2022]
Abstract
Gamma-aminobutyric acid (GABA)-ergic disturbances are hallmark features of schizophrenia and other neuropsychiatric disorders and encompass multiple interneuronal cell types. Using bacterial artificial chromosome-driven, miRNA silencing technology we generated transgenic mouse lines that suppress glutamic acid decarboxylase 1 (GAD1) in either cholecystokinin (CCK)- or neuropeptide Y (NPY)-expressing interneurons. In situ lipidomic and proteomic analyses on brain tissue sections revealed distinct, brain region-specific profiles in each transgenic line. Behavioral analyses revealed that suppression of GAD1 in CCK+ interneurons resulted in locomotor and olfactory sensory changes, whereas suppression in NPY+ interneurons affected anxiety-related behaviors and social interaction. Both transgenic mouse lines had altered sensitivity to amphetamine albeit in opposite directions. Together, these data argue that reduced GAD1 expression leads to altered molecular and behavioral profiles in a cell type-dependent manner, and that these subpopulations of interneurons are strong and opposing modulators of dopamine system function. Furthermore, our findings also support the hypothesis that neuronal networks are differentially controlled by diverse inhibitory subnetworks.
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