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Smith I, Calegari F. Cyclin D1 Again Caught in the Act: Dyrk1a Links G1 and Neurogenesis in Down Syndrome. EBioMedicine 2015; 2:96-7. [PMID: 26137545 PMCID: PMC4484827 DOI: 10.1016/j.ebiom.2015.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
| | - Federico Calegari
- DFG—Research Center and Cluster of Excellence for Regenerative Therapies, TU-Dresden, Fetscherstrasse 105, 01307 Dresden, Germany
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102
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Fraga DFB, Pereira KDR, Dornelles S, Olchik MR, Levy DS. Avaliação da deglutição em lactentes com cardiopatia congênita e síndrome de Down: estudo de casos. REVISTA CEFAC 2015. [DOI: 10.1590/1982-0216201514613] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
O presente estudo teve por objetivo realizar avaliação fonoaudiológica da deglutição em lactentes com diagnóstico de síndrome de Down e cardiopatia congênita (DSAV tipo A de Rastelli) internados na unidade 2A e Unidade de Tratamento Intensivo Pediátrica da instituição de origem, com suspeita de dificuldade de deglutição, encaminhados ao serviço de fonoaudiologia. Trata-se de uma pesquisa de caráter descritivo-qualitativo, nessa foi possível avaliar dois lactentes durante o período de janeiro a outubro de 2012. Utilizou-se um protocolo de perfil da amostra para a coleta de dados sobre histórico clínico e diagnósticos dos prontuários dos pacientes, além do instrumento de avaliação para prontidão do prematuro para alimentação oral proposto por Fujinaga (2002) para avaliação clínica da deglutição. Os pacientes apresentaram como resultados a presença de disfagia orofaríngea e escores baixos inviabilizando a alimentação exclusivamente por via oral. A conduta terapêutica foi de estimulação oral e volume de alimentação controlado para alimentação oral. Os achados corroboram a literatura no que diz respeito à relação entre disfagia, cardiopatia congênita, síndromes genéticas e alterações miofuncionais orofaciais. Conclui-se que a disfagia apresentou-se como um sintoma dificultante para a alimentação por via oral de forma segura e eficaz para todos os lactentes estudados. Estudos prospectivos com um número maior de sujeitos são necessários para contribuir com a série de casos e, desta forma, identificar outros fatores de risco para disfagia bem como condutas terapêuticas específicas para crianças com síndrome de Down e distúrbios da deglutição associados.
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103
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Najas S, Arranz J, Lochhead PA, Ashford AL, Oxley D, Delabar JM, Cook SJ, Barallobre MJ, Arbonés ML. DYRK1A-mediated Cyclin D1 Degradation in Neural Stem Cells Contributes to the Neurogenic Cortical Defects in Down Syndrome. EBioMedicine 2015; 2:120-34. [PMID: 26137553 PMCID: PMC4484814 DOI: 10.1016/j.ebiom.2015.01.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 01/16/2015] [Accepted: 01/16/2015] [Indexed: 01/02/2023] Open
Abstract
Alterations in cerebral cortex connectivity lead to intellectual disability and in Down syndrome, this is associated with a deficit in cortical neurons that arises during prenatal development. However, the pathogenic mechanisms that cause this deficit have not yet been defined. Here we show that the human DYRK1A kinase on chromosome 21 tightly regulates the nuclear levels of Cyclin D1 in embryonic cortical stem (radial glia) cells, and that a modest increase in DYRK1A protein in transgenic embryos lengthens the G1 phase in these progenitors. These alterations promote asymmetric proliferative divisions at the expense of neurogenic divisions, producing a deficit in cortical projection neurons that persists in postnatal stages. Moreover, radial glial progenitors in the Ts65Dn mouse model of Down syndrome have less Cyclin D1, and Dyrk1a is the triplicated gene that causes both early cortical neurogenic defects and decreased nuclear Cyclin D1 levels in this model. These data provide insights into the mechanisms that couple cell cycle regulation and neuron production in cortical neural stem cells, emphasizing that the deleterious effect of DYRK1A triplication in the formation of the cerebral cortex begins at the onset of neurogenesis, which is relevant to the search for early therapeutic interventions in Down syndrome.
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Affiliation(s)
- Sònia Najas
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 08028 Barcelona, Spain
| | - Juan Arranz
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 08028 Barcelona, Spain
| | - Pamela A. Lochhead
- Signalling Programme, The Babraham Institute, Babraham Research Campus, CB22 3AT Cambridge, UK
| | - Anne L. Ashford
- Signalling Programme, The Babraham Institute, Babraham Research Campus, CB22 3AT Cambridge, UK
| | - David Oxley
- Proteomics Group, The Babraham Institute, Babraham Research Campus, CB22 3AT Cambridge, UK
| | - Jean M. Delabar
- Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, UM 75, U 1127, UMR 7225, ICM, 75013 Paris, France
| | - Simon J. Cook
- Signalling Programme, The Babraham Institute, Babraham Research Campus, CB22 3AT Cambridge, UK
| | - María José Barallobre
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 08028 Barcelona, Spain
| | - Maria L. Arbonés
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 08028 Barcelona, Spain
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104
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Singh N, Dutka T, Devenney BM, Kawasaki K, Reeves RH, Richtsmeier JT. Acute upregulation of hedgehog signaling in mice causes differential effects on cranial morphology. Dis Model Mech 2014; 8:271-9. [PMID: 25540129 PMCID: PMC4348564 DOI: 10.1242/dmm.017889] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hedgehog (HH) signaling, and particularly signaling by sonic hedgehog (SHH), is implicated in several essential activities during morphogenesis, and its misexpression causes a number of developmental disorders in humans. In particular, a reduced mitogenic response of cerebellar granule cell precursors to SHH signaling in a mouse model for Down syndrome (DS), Ts65Dn, is substantially responsible for reduced cerebellar size. A single treatment of newborn trisomic mice with an agonist of the SHH pathway (SAG) normalizes cerebellar morphology and restores some cognitive deficits, suggesting a possible therapeutic application of SAG for treating the cognitive impairments of DS. Although the beneficial effects on the cerebellum are compelling, inappropriate activation of the HH pathway causes anomalies elsewhere in the head, particularly in the formation and patterning of the craniofacial skeleton. To determine whether an acute treatment of SAG has an effect on craniofacial morphology, we quantitatively analyzed the cranial form of adult euploid and Ts65Dn mice that were injected with either SAG or vehicle at birth. We found significant deformation of adult craniofacial shape in some animals that had received SAG at birth. The most pronounced differences between the treated and untreated mice were in the midline structures of the facial skeleton. The SAG-driven craniofacial dysmorphogenesis was dose-dependent and possibly incompletely penetrant at lower concentrations. Our findings illustrate that activation of HH signaling, even with an acute postnatal stimulation, can lead to localized dysmorphology of the skull by generating modular shape changes in the facial skeleton. These observations have important implications for translating HH-agonist-based treatments for DS.
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Affiliation(s)
- Nandini Singh
- Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA
| | - Tara Dutka
- Johns Hopkins University School of Medicine, Institute of Genetic Medicine, Baltimore, MD 21287, USA
| | - Benjamin M Devenney
- Johns Hopkins University School of Medicine, Department of Physiology, Baltimore, MD 21205, USA
| | - Kazuhiko Kawasaki
- Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA
| | - Roger H Reeves
- Johns Hopkins University School of Medicine, Institute of Genetic Medicine, Baltimore, MD 21287, USA Johns Hopkins University School of Medicine, Department of Physiology, Baltimore, MD 21205, USA
| | - Joan T Richtsmeier
- Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA
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105
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Liu B, Filippi S, Roy A, Roberts I. Stem and progenitor cell dysfunction in human trisomies. EMBO Rep 2014; 16:44-62. [PMID: 25520324 DOI: 10.15252/embr.201439583] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Trisomy 21, the commonest constitutional aneuploidy in humans, causes profound perturbation of stem and progenitor cell growth, which is both cell context dependent and developmental stage specific and mediated by complex genetic mechanisms beyond increased Hsa21 gene dosage. While proliferation of fetal hematopoietic and testicular stem/progenitors is increased and may underlie increased susceptibility to childhood leukemia and testicular cancer, fetal stem/progenitor proliferation in other tissues is markedly impaired leading to the characteristic craniofacial, neurocognitive and cardiac features in individuals with Down syndrome. After birth, trisomy 21-mediated premature aging of stem/progenitor cells may contribute to the progressive multi-system deterioration, including development of Alzheimer's disease.
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Affiliation(s)
- Binbin Liu
- Department of Paediatrics and Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, Oxford, UK
| | - Sarah Filippi
- Department of Statistics, University of Oxford, Oxford, UK
| | - Anindita Roy
- Centre for Haematology, Imperial College London, London, UK
| | - Irene Roberts
- Department of Paediatrics and Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, Oxford, UK
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106
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Evidence of altered age-related brain cytoarchitecture in mouse models of down syndrome: a diffusional kurtosis imaging study. Magn Reson Imaging 2014; 33:437-47. [PMID: 25527393 DOI: 10.1016/j.mri.2014.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/26/2014] [Accepted: 12/01/2014] [Indexed: 11/22/2022]
Abstract
Mouse models of Down syndrome (DS) exhibit abnormal brain developmental and neurodegenerative changes similar to those seen in individuals with DS. Although DS mice have been well characterized cognitively and morphologically there are no prior reports utilizing diffusion MRI. In this study we investigated the ability of diffusional kurtosis imaging (DKI) to detect the progressive developmental and neurodegenerative changes in the Ts65Dn (TS) DS mouse model. TS mice displayed higher diffusional kurtosis (DK) in the frontal cortex (FC) compared to normal mice at 2months of age. At 5months of age, TS mice had lower radial kurtosis in the striatum (ST), which persisted in the 8-month-old mice. The TS mice exhibited lower DK metrics values in the dorsal hippocampus (HD) at all ages, and the group difference in this region was larger at 8-months. Regression analysis showed that normal mice had a significant age-related increase in DK metrics in FC, ST and HD. On the contrary, the TS mice lacked significant age-related increase in DK metrics in FC and ST. Although preliminary, these results demonstrate that DK metrics can detect TS brain developmental and neurodegenerative abnormalities.
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107
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Differentially expressed microRNAs in maternal plasma for the noninvasive prenatal diagnosis of Down syndrome (trisomy 21). BIOMED RESEARCH INTERNATIONAL 2014; 2014:402475. [PMID: 25478570 PMCID: PMC4244954 DOI: 10.1155/2014/402475] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 09/09/2014] [Indexed: 11/18/2022]
Abstract
OBJECTIVES Most developmental processes are under the control of small regulatory RNAs called microRNAs (miRNAs). We hypothesize that different fetal developmental processes might be reflected by extracellular miRNAs in maternal plasma and may be utilized as biomarkers for the noninvasive prenatal diagnosis of chromosomal aneuploidies. In this proof-of-concept study, we report on the identification of extracellular miRNAs in maternal plasma of Down syndrome (DS) pregnancies. METHODS Using high-throughput quantitative PCR (HT-qPCR), 1043 miRNAs were investigated in maternal plasma via comparison of seven DS pregnancies with age and fetal sex matched controls. RESULTS Six hundred and ninety-five miRNAs were identified. Thirty-six significantly differentially expressed mature miRNAs were identified as potential biomarkers. Hierarchical cluster analysis of these miRNAs resulted in the clear discrimination of DS from euploid pregnancies. Gene targets of the differentially expressed miRNAs were enriched in signaling pathways such as mucin type-O-glycans, ECM-receptor interactions, TGF-beta, and endocytosis, which have been previously associated with DS. CONCLUSIONS miRNAs are promising and stable biomarkers for a broad range of diseases and may allow a reliable, cost-efficient diagnostic tool for the noninvasive prenatal diagnosis of DS.
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108
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Contribution of copy-number variation to Down syndrome-associated atrioventricular septal defects. Genet Med 2014; 17:554-60. [PMID: 25341113 PMCID: PMC4408203 DOI: 10.1038/gim.2014.144] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/11/2014] [Indexed: 01/12/2023] Open
Abstract
Purpose The goal of this study was to identify the contribution of large copy number variants (CNV) to Down syndrome (DS) associated atrioventricular septal defects (AVSD), whose risk in the trisomic population is 2000-fold more compared to general disomic population. Methods Genome-wide CNV analysis was performed on 452 individuals with DS (210 cases with complete AVSD; 242 controls with structurally normal hearts) using Affymetrix SNP 6.0 arrays, making this the largest heart study conducted to date on a trisomic background. Results Large common CNVs with substantial effect sizes (OR>2.0) do not account for the increased risk observed in DS-associated AVSD. In contrast, cases had a greater burden of large rare deletions (p<0.01) and intersected more genes (p<0.007) when compared to controls. We also observed a suggestive enrichment of deletions intersecting ciliome genes in cases compared to controls. Conclusion Our data provide strong evidence that large rare deletions increase the risk of DS-associated AVSD, while large common CNVs do not appear to increase the risk of DS-associated AVSD. The genetic architecture of AVSD is complex and multifactorial in nature.
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109
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Ishihara K, Kanai S, Sago H, Yamakawa K, Akiba S. Comparative proteomic profiling reveals aberrant cell proliferation in the brain of embryonic Ts1Cje, a mouse model of Down syndrome. Neuroscience 2014; 281:1-15. [PMID: 25261685 DOI: 10.1016/j.neuroscience.2014.09.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/13/2014] [Accepted: 09/17/2014] [Indexed: 12/31/2022]
Abstract
To identify molecular candidates involved in brain disabilities of Ts1Cje, a mouse model of Down syndrome (DS), we performed comparative proteomic analyses. Proteins extracted from the brains of postnatal wild-type (WT) and Ts1Cje mice were analyzed by two-dimensional gel electrophoresis (2-DE). No differences were detected in the proteins expressed in the whole brain between WT and Ts1Cje mice at postnatal day 0 and 3months of age. Five spots with differential expression in the brains of Ts1Cje mice were detected by 2-DE of brain proteins from WT and Ts1Cje embryos at embryonic day 14.5 (E14.5). These differentially expressed proteins in Ts1Cje embryos were identified as calcyclin-binding protein (CACYBP), nucleoside diphosphate kinase-B (NDPK-B), transketolase (TK), pyruvate kinase (PK), and 60S acidic ribosomal protein P0 (RPLP0) by peptide mass fingerprinting. CACYBP and NDPK-B were involved in cell proliferation, whereas TK and PK were associated with energy metabolism. Experiments on cell proliferation, an in vivo bromodeoxyuridine (BrdU)-labeling experiment, and immunohistochemical analysis for phospho-histone H3 (an M-phase marker) demonstrated increased numbers of BrdU-positive and M-phase cells in the ganglionic eminence. Our findings suggest that the dysregulated expression of proteins demonstrated by comparative proteomic analysis could be a factor in increased cell proliferation, which may be associated with abnormalities in DS brain during embryonic life.
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Affiliation(s)
- K Ishihara
- Department of Pathological Biochemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan; Laboratory for Neurogenetics, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako City, Saitama 351-0198, Japan.
| | - S Kanai
- Department of Pathological Biochemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
| | - H Sago
- Center for Maternal-Fetal and Neonatal Medicine, National Center for Child Health and Development, 2-10-1 Okura Setagaya-ku, Tokyo 157-8535, Japan
| | - K Yamakawa
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako City, Saitama 351-0198, Japan
| | - S Akiba
- Department of Pathological Biochemistry, Kyoto Pharmaceutical University, 5 Misasagi-Nakauchi-cho, Yamashina-ku, Kyoto 607-8414, Japan
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110
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A quantitative transcriptome reference map of the normal human brain. Neurogenetics 2014; 15:267-87. [PMID: 25185649 DOI: 10.1007/s10048-014-0419-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/08/2014] [Indexed: 10/24/2022]
Abstract
We performed an innovative systematic meta-analysis of 60 gene expression profiles of whole normal human brain, to provide a quantitative transcriptome reference map of it, i.e. a reference typical value of expression for each of the 39,250 known, mapped and 26,026 uncharacterized (unmapped) transcripts. To this aim, we used the software named Transcriptome Mapper (TRAM), which is able to generate transcriptome maps based on gene expression data from multiple sources. We also analyzed differential expression by comparing the brain transcriptome with those derived from human foetal brain gene expression, from a pool of human tissues (except the brain) and from the two normal human brain regions cerebellum and cerebral cortex, which are two of the main regions severely affected when cognitive impairment occurs, as happens in the case of trisomy 21. Data were downloaded from microarray databases, processed and analyzed using TRAM software and validated in vitro by assaying gene expression through several magnitude orders by 'real-time' reverse transcription polymerase chain reaction (RT-PCR). The excellent agreement between in silico and experimental data suggested that our transcriptome maps may be a useful quantitative reference benchmark for gene expression studies related to the human brain. Furthermore, our analysis yielded biological insights about those genes which have an intrinsic over-/under-expression in the brain, in addition offering a basis for the regional analysis of gene expression. This could be useful for the study of chromosomal alterations associated to cognitive impairment, such as trisomy 21, the most common genetic cause of intellectual disability.
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111
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Wang X, Huang T, Bu G, Xu H. Dysregulation of protein trafficking in neurodegeneration. Mol Neurodegener 2014; 9:31. [PMID: 25152012 PMCID: PMC4237948 DOI: 10.1186/1750-1326-9-31] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/14/2014] [Indexed: 02/02/2023] Open
Abstract
Intracellular protein trafficking plays an important role in neuronal function and survival. Protein misfolding is a common theme found in many neurodegenerative diseases, and intracellular trafficking machinery contributes to the pathological accumulation and clearance of misfolded proteins. Although neurodegenerative diseases exhibit distinct pathological features, abnormal endocytic trafficking is apparent in several neurodegenerative diseases, such as Alzheimer’s disease (AD), Down syndrome (DS) and Parkinson’s disease (PD). In this review, we will focus on protein sorting defects in three major neurodegenerative diseases, including AD, DS and PD. An important pathological feature of AD is the presence of extracellular senile plaques in the brain. Senile plaques are composed of β-amyloid (Aβ) peptide aggregates. Multiple lines of evidence demonstrate that over-production/aggregation of Aβ in the brain is a primary cause of AD and attenuation of Aβ generation has become a topic of extreme interest in AD research. Aβ is generated from β-amyloid precursor protein (APP) through sequential cleavage by β-secretase and the γ-secretase complex. Alternatively, APP can be cleaved by α-secretase within the Aβ domain to release soluble APPα which precludes Aβ generation. DS patients display a strikingly similar pathology to AD patients, including the generation of neuronal amyloid plaques. Moreover, all DS patients develop an AD-like neuropathology by their 40 s. Therefore, understanding the metabolism/processing of APP and how these underlying mechanisms may be pathologically compromised is crucial for future AD and DS therapeutic strategies. Evidence accumulated thus far reveals that synaptic vesicle regulation, endocytic trafficking, and lysosome-mediated autophagy are involved in increased susceptibility to PD. Here we review current knowledge of endosomal trafficking regulation in AD, DS and PD.
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Affiliation(s)
| | | | | | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, College of Medicine, Xiamen University, Xiamen, Fujian 361102, China.
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112
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Guedj F, Pennings JLA, Wick HC, Bianchi DW. Analysis of adult cerebral cortex and hippocampus transcriptomes reveals unique molecular changes in the Ts1Cje mouse model of down syndrome. Brain Pathol 2014; 25:11-23. [PMID: 24916381 DOI: 10.1111/bpa.12151] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 05/07/2014] [Indexed: 12/22/2022] Open
Abstract
We investigated gene expression and functional differences between Ts1Cje mice and wild-type (WT) littermates in adult cerebral cortex and hippocampus. These two brain regions are affected in people with Down syndrome, but have not been previously molecularly characterized in Ts1Cje mice. Total RNA was prepared from the brains of 8-10-week-old Ts1Cje mice (n = 6) and WT littermates (n = 5) and hybridized to Affymetrix 1.0 ST gene mouse arrays. Differentially regulated genes were identified and used to perform in silico functional analyses to better characterize dysregulated pathways in both brain regions. Hippocampus had more significantly differentially expressed genes compared with cortex (30 vs. 7 at a Benjamini-Hochberg false discovery rate of 20%). We identified novel genes that were differentially regulated in adult brains, including Cyb5r1, Fsbp, Vmn2r110, Snd1 and Zhx2. Functional analyses in Ts1Cje mice highlighted the importance of NFAT signaling, oxidative stress, neuroinflammation and olfactory perception via G-protein signaling. In a comparison of adult Ts1Cje and WT brains, we identified new genes and pathway differences in the cortex and hippocampus. Our analyses identified physiologically relevant pathways that can serve as targets for the development of future treatments to improve neurocognition in Down syndrome.
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Affiliation(s)
- Faycal Guedj
- Mother Infant Research Institute, Floating Hospital for Children, Tufts Medical Center, Boston, MA, USA
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113
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Functional transcriptome analysis of the postnatal brain of the Ts1Cje mouse model for Down syndrome reveals global disruption of interferon-related molecular networks. BMC Genomics 2014; 15:624. [PMID: 25052193 PMCID: PMC4124147 DOI: 10.1186/1471-2164-15-624] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/16/2014] [Indexed: 12/25/2022] Open
Abstract
Background The Ts1Cje mouse model of Down syndrome (DS) has partial triplication of mouse chromosome 16 (MMU16), which is partially homologous to human chromosome 21. These mice develop various neuropathological features identified in DS individuals. We analysed the effect of partial triplication of the MMU16 segment on global gene expression in the cerebral cortex, cerebellum and hippocampus of Ts1Cje mice at 4 time-points: postnatal day (P)1, P15, P30 and P84. Results Gene expression profiling identified a total of 317 differentially expressed genes (DEGs), selected from various spatiotemporal comparisons, between Ts1Cje and disomic mice. A total of 201 DEGs were identified from the cerebellum, 129 from the hippocampus and 40 from the cerebral cortex. Of these, only 18 DEGs were identified as common to all three brain regions and 15 were located in the triplicated segment. We validated 8 selected DEGs from the cerebral cortex (Brwd1, Donson, Erdr1, Ifnar1, Itgb8, Itsn1, Mrps6 and Tmem50b), 18 DEGs from the cerebellum (Atp5o, Brwd1, Donson, Dopey2, Erdr1, Hmgn1, Ifnar1, Ifnar2, Ifngr2, Itgb8, Itsn1, Mrps6, Paxbp1, Son, Stat1, Tbata, Tmem50b and Wrb) and 11 DEGs from the hippocampus (Atp5o, Brwd1, Cbr1, Donson, Erdr1, Itgb8, Itsn1, Morc3, Son, Tmem50b and Wrb). Functional clustering analysis of the 317 DEGs identified interferon-related signal transduction as the most significantly dysregulated pathway in Ts1Cje postnatal brain development. RT-qPCR and western blotting analysis showed both Ifnar1 and Stat1 were over-expressed in P84 Ts1Cje cerebral cortex and cerebellum as compared to wild type littermates. Conclusions These findings suggest over-expression of interferon receptor may lead to over-stimulation of Jak-Stat signaling pathway which may contribute to the neuropathology in Ts1Cje or DS brain. The role of interferon mediated activation or inhibition of signal transduction including Jak-Stat signaling pathway has been well characterized in various biological processes and disease models including DS but information pertaining to the role of this pathway in the development and function of the Ts1Cje or DS brain remains scarce and warrants further investigation. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-624) contains supplementary material, which is available to authorized users.
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114
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Daunhauer LA, Fidler DJ, Hahn L, Will E, Lee NR, Hepburn S. Profiles of everyday executive functioning in young children with down syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2014; 119:303-18. [PMID: 25007296 PMCID: PMC4512669 DOI: 10.1352/1944-7558-119.4.303] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We investigated executive functioning (EF) in children with Down syndrome (DS; n = 25) and typically developing (TD) children matched for mental age (MA; n = 23) using the Behavior Rating Inventory of Executive Function-Preschool. We sought to (1) compare children with DS to a developmentally matched control group, and (2) to characterize the EF profile of children with DS. Across teacher and parent reports, significant deficits in working memory and planning were observed in the DS group. Parents, but not teachers, of children with DS also reported difficulties in inhibitory control relative to the comparison group. Results extend earlier findings regarding EF impairments in children with DS. The complementary role inhibitory control may play in this profile is discussed.
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115
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Barallobre MJ, Perier C, Bové J, Laguna A, Delabar JM, Vila M, Arbonés ML. DYRK1A promotes dopaminergic neuron survival in the developing brain and in a mouse model of Parkinson's disease. Cell Death Dis 2014; 5:e1289. [PMID: 24922073 PMCID: PMC4611726 DOI: 10.1038/cddis.2014.253] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 04/22/2014] [Accepted: 05/08/2014] [Indexed: 12/18/2022]
Abstract
In the brain, programmed cell death (PCD) serves to adjust the numbers of the different types of neurons during development, and its pathological reactivation in the adult leads to neurodegeneration. Dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A) is a pleiotropic kinase involved in neural proliferation and cell death, and its role during brain growth is evolutionarily conserved. Human DYRK1A lies in the Down syndrome critical region on chromosome 21, and heterozygous mutations in the gene cause microcephaly and neurological dysfunction. The mouse model for DYRK1A haploinsufficiency (the Dyrk1a(+/-) mouse) presents neuronal deficits in specific regions of the adult brain, including the substantia nigra (SN), although the mechanisms underlying these pathogenic effects remain unclear. Here we study the effect of DYRK1A copy number variation on dopaminergic cell homeostasis. We show that mesencephalic DA (mDA) neurons are generated in the embryo at normal rates in the Dyrk1a haploinsufficient model and in a model (the mBACtgDyrk1a mouse) that carries three copies of Dyrk1a. We also show that the number of mDA cells diminishes in postnatal Dyrk1a(+/-) mice and increases in mBACtgDyrk1a mice due to an abnormal activity of the mitochondrial caspase9 (Casp9)-dependent apoptotic pathway during the main wave of PCD that affects these neurons. In addition, we show that the cell death induced by 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP), a toxin that activates Casp9-dependent apoptosis in mDA neurons, is attenuated in adult mBACtgDyrk1a mice, leading to an increased survival of SN DA neurons 21 days after MPTP intoxication. Finally, we present data indicating that Dyrk1a phosphorylation of Casp9 at the Thr125 residue is the mechanism by which this kinase hinders both physiological and pathological PCD in mDA neurons. These data provide new insight into the mechanisms that control cell death in brain DA neurons and they show that deregulation of developmental apoptosis may contribute to the phenotype of patients with imbalanced DYRK1A gene dosage.
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Affiliation(s)
- M J Barallobre
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - C Perier
- Neurodegenerative Diseases Research Group, Vall d'Hebron Research Institute and Center for Networked Biomedical Research on Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - J Bové
- Neurodegenerative Diseases Research Group, Vall d'Hebron Research Institute and Center for Networked Biomedical Research on Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
| | - A Laguna
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - J M Delabar
- Unité de Biologie Fonctionnelle et Adaptative, EAC4413 CNRS, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - M Vila
- Neurodegenerative Diseases Research Group, Vall d'Hebron Research Institute and Center for Networked Biomedical Research on Neurodegenerative Diseases (CIBERNED), Barcelona, Spain
- Department of Biochemistry and Molecular Biology, Autonomous University of Barcelona (UAB), Barcelona, Spain
- Catalan Institute for Research and Advanced Studies (ICREA), Barcelona, Spain
| | - M L Arbonés
- Department of Developmental Biology, Instituto de Biología Molecular de Barcelona, CSIC, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Barcelona, Spain
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116
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Soppa U, Schumacher J, Florencio Ortiz V, Pasqualon T, Tejedor FJ, Becker W. The Down syndrome-related protein kinase DYRK1A phosphorylates p27(Kip1) and Cyclin D1 and induces cell cycle exit and neuronal differentiation. Cell Cycle 2014; 13:2084-100. [PMID: 24806449 PMCID: PMC4111700 DOI: 10.4161/cc.29104] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 05/02/2014] [Accepted: 05/03/2014] [Indexed: 01/12/2023] Open
Abstract
A fundamental question in neurobiology is how the balance between proliferation and differentiation of neuronal precursors is maintained to ensure that the proper number of brain neurons is generated. Substantial evidence implicates DYRK1A (dual specificity tyrosine-phosphorylation-regulated kinase 1A) as a candidate gene responsible for altered neuronal development and brain abnormalities in Down syndrome. Recent findings support the hypothesis that DYRK1A is involved in cell cycle control. Nonetheless, how DYRK1A contributes to neuronal cell cycle regulation and thereby affects neurogenesis remains poorly understood. In the present study we have investigated the mechanisms by which DYRK1A affects cell cycle regulation and neuronal differentiation in a human cell model, mouse neurons, and mouse brain. Dependent on its kinase activity and correlated with the dosage of overexpression, DYRK1A blocked proliferation of SH-SY5Y neuroblastoma cells within 24 h and arrested the cells in G₁ phase. Sustained overexpression of DYRK1A induced G₀ cell cycle exit and neuronal differentiation. Furthermore, we provide evidence that DYRK1A modulated protein stability of cell cycle-regulatory proteins. DYRK1A reduced cellular Cyclin D1 levels by phosphorylation on Thr286, which is known to induce proteasomal degradation. In addition, DYRK1A phosphorylated p27(Kip1) on Ser10, resulting in protein stabilization. Inhibition of DYRK1A kinase activity reduced p27(Kip1) Ser10 phosphorylation in cultured hippocampal neurons and in embryonic mouse brain. In aggregate, these results suggest a novel mechanism by which overexpression of DYRK1A may promote premature neuronal differentiation and contribute to altered brain development in Down syndrome.
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Affiliation(s)
- Ulf Soppa
- Institute of Pharmacology and Toxicology; Medical Faculty; RWTH Aachen University; Aachen, Germany
- Instituto de Neurociencias; Consejo Superior de Investigaciones Cientificas (CSIC) and Universidad Miguel Hernandez; Alicante, Spain
| | - Julian Schumacher
- Institute of Pharmacology and Toxicology; Medical Faculty; RWTH Aachen University; Aachen, Germany
| | - Victoria Florencio Ortiz
- Instituto de Neurociencias; Consejo Superior de Investigaciones Cientificas (CSIC) and Universidad Miguel Hernandez; Alicante, Spain
| | - Tobias Pasqualon
- Institute of Pharmacology and Toxicology; Medical Faculty; RWTH Aachen University; Aachen, Germany
| | - Francisco J Tejedor
- Instituto de Neurociencias; Consejo Superior de Investigaciones Cientificas (CSIC) and Universidad Miguel Hernandez; Alicante, Spain
| | - Walter Becker
- Institute of Pharmacology and Toxicology; Medical Faculty; RWTH Aachen University; Aachen, Germany
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117
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Inglis A, Lohn Z, Austin JC, Hippman C. A 'cure' for Down syndrome: what do parents want? Clin Genet 2014; 86:310-7. [PMID: 24548046 DOI: 10.1111/cge.12364] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 02/11/2014] [Accepted: 02/16/2014] [Indexed: 12/12/2022]
Abstract
Recent advancements in molecular genetics raise the possibility that therapeutics or a 'cure' for Down syndrome (DS) may become available. However, there are no data regarding how parents of children with DS perceive the possibility of mitigating specific manifestations such as the intellectual disability (ID) associated with DS, or curing the condition entirely. To explore these issues, we distributed a questionnaire to members of the Lower Mainland Down Syndrome Society in British Columbia, Canada. Questionnaires were completed by 101 parents (response rate=41%). A majority (61%) viewed the possibility of reversing ID in DS positively, but only 41% said that they would 'cure' their child of DS if it were possible. Twenty-seven percent of respondents said they would not 'cure' their child, and 32% were unsure if they would 'cure' their child. The most commonly cited motivation for opting for a 'cure' was to increase their child's independence. However, parental attitudes' towards a 'cure' for DS were complex, affected by ethical issues, perceived societal values, and pragmatic factors such as the age of the individual and long-term care-giving burden. These findings could be used by healthcare professionals supporting families who include a member with DS and to direct future research.
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Affiliation(s)
- A Inglis
- Department of Psychiatry, University of British Columbia, Vancouver, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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118
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Martínez-Cué C, Delatour B, Potier MC. Treating enhanced GABAergic inhibition in Down syndrome: use of GABA α5-selective inverse agonists. Neurosci Biobehav Rev 2014; 46 Pt 2:218-27. [PMID: 24412222 DOI: 10.1016/j.neubiorev.2013.12.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/27/2013] [Accepted: 12/16/2013] [Indexed: 11/27/2022]
Abstract
Excess inhibition in the brain of individuals carrying an extra copy of chromosome 21 could be responsible for cognitive deficits observed throughout their lives. A change in the excitatory/inhibitory balance in adulthood would alter synaptic plasticity, potentially triggering learning and memory deficits. γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mature central nervous system and binds to GABAA receptors, opens a chloride channel, and reduces neuronal excitability. In this review we discuss methods to alleviate neuronal inhibition in a mouse model of Down syndrome, the Ts65Dn mouse, using either an antagonist (pentylenetetrazol) or two different inverse agonists selective for the α5-subunit containing receptor. Both inverse agonists, which reduce inhibitory GABAergic transmission, could rescue learning and memory deficits in Ts65Dn mice. We also discuss safety issues since modulation of the excitatory-inhibitory balance to improve cognition without inducing seizures remains particularly difficult when using GABA antagonists.
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Affiliation(s)
- Carmen Martínez-Cué
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Cantabria, Santander, Spain
| | - Benoît Delatour
- Institut du Cerveau et de Moelle Epinière, CNRS UMR7225, INSERM U1127, UPMC, IHUA-ICM, Hôpital Pitié-Salpêtrière, Paris, France
| | - Marie-Claude Potier
- Institut du Cerveau et de Moelle Epinière, CNRS UMR7225, INSERM U1127, UPMC, IHUA-ICM, Hôpital Pitié-Salpêtrière, Paris, France.
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119
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Briggs JA, Sun J, Shepherd J, Ovchinnikov DA, Chung TL, Nayler SP, Kao LP, Morrow CA, Thakar NY, Soo SY, Peura T, Grimmond S, Wolvetang EJ. Integration-free induced pluripotent stem cells model genetic and neural developmental features of down syndrome etiology. Stem Cells 2014; 31:467-78. [PMID: 23225669 DOI: 10.1002/stem.1297] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/21/2012] [Indexed: 01/08/2023]
Abstract
Down syndrome (DS) is the most frequent cause of human congenital mental retardation. Cognitive deficits in DS result from perturbations of normal cellular processes both during development and in adult tissues, but the mechanisms underlying DS etiology remain poorly understood. To assess the ability of induced pluripotent stem cells (iPSCs) to model DS phenotypes, as a prototypical complex human disease, we generated bona fide DS and wild-type (WT) nonviral iPSCs by episomal reprogramming. DS iPSCs selectively overexpressed chromosome 21 genes, consistent with gene dosage, which was associated with deregulation of thousands of genes throughout the genome. DS and WT iPSCs were neurally converted at >95% efficiency and had remarkably similar lineage potency, differentiation kinetics, proliferation, and axon extension at early time points. However, at later time points DS cultures showed a twofold bias toward glial lineages. Moreover, DS neural cultures were up to two times more sensitive to oxidative stress-induced apoptosis, and this could be prevented by the antioxidant N-acetylcysteine. Our results reveal a striking complexity in the genetic alterations caused by trisomy 21 that are likely to underlie DS developmental phenotypes, and indicate a central role for defective early glial development in establishing developmental defects in DS brains. Furthermore, oxidative stress sensitivity is likely to contribute to the accelerated neurodegeneration seen in DS, and we provide proof of concept for screening corrective therapeutics using DS iPSCs and their derivatives. Nonviral DS iPSCs can therefore model features of complex human disease in vitro and provide a renewable and ethically unencumbered discovery platform.
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Affiliation(s)
- James A Briggs
- Australian Institute for Bioengineering and Nanotechnology,The University of Queensland, St Lucia, Queensland, Australia
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120
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Guedj F, Bianchi DW. Noninvasive prenatal testing creates an opportunity for antenatal treatment of Down syndrome. Prenat Diagn 2014; 33:614-8. [PMID: 23595836 DOI: 10.1002/pd.4134] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Trisomy 21 (T21) is the most common autosomal aneuploidy that is associated with intellectual disability. It is the focus of many prenatal screening programs across the globe. Pregnant women who receive a prenatal diagnosis of T21 in their fetus currently have the option of continuing or terminating their pregnancy, but no fetal treatment is available. In this paper, we review compelling morphogenetic, cellular, and molecular studies that, taken together, suggest that there is an important window of opportunity during fetal life to positively impact brain development to improve postnatal neurocognition and behavior. Although substantial progress has been made in understanding the basic neurobiology of Down syndrome (DS), the majority of pre-clinical trials is currently focused on adults. There are a number of challenges in the identification and development of novel antenatal therapies for DS, including the lack of toxicity and teratogenicity for the pregnant woman and the fetus, evidence that the compounds can cross the placenta and achieve therapeutic levels, and the demonstration of clinical improvement. Preliminary experiments in mouse models suggest that prenatal treatment of DS is an achievable goal.
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Affiliation(s)
- Faycal Guedj
- Mother Infant Research Institute, Tufts Medical Center and Floating Hospital for Children, Boston, MA, USA
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121
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Sosa LJ, Postma NL, Estrada-Bernal A, Hanna M, Guo R, Busciglio J, Pfenninger KH. Dosage of amyloid precursor protein affects axonal contact guidance in Down syndrome. FASEB J 2013; 28:195-205. [PMID: 24036883 DOI: 10.1096/fj.13-232686] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Amyloid precursor protein (APP), encoded on Hsa21, functions as a cell adhesion molecule (CAM) in axonal growth cones (GCs) of the developing brain. We show here that axonal GCs of human fetal Down syndrome (DS) neurons (and of a DS mouse model) overexpress APP protein relative to euploid controls. We investigated whether DS neurons generate an abnormal, APP-dependent GC phenotype in vitro. On laminin, which binds APP and β1 integrins (Itgb1), DS neurons formed enlarged and faster-advancing GCs compared to controls. On peptide matrices that bind APP only, but not on those binding exclusively Itgb1 or L1CAM, DS GCs were significantly enlarged (2.0-fold), formed increased close adhesions (1.8-fold), and advanced faster (1.4-fold). In assays involving alternating stripes of monospecific matrices, human control GCs exhibited no preference for any of the substrates, whereas DS GCs preferred the APP-binding matrix (cross-over decreased significantly from 48.2 to 27.2%). Reducing APP expression in DS GCs with siRNA normalized most measures of the phenotype, including substrate choice. These experiments show that human DS neurons exhibit an APP-dependent, abnormal GC phenotype characterized by increased adhesion and altered contact guidance. The results suggest that APP overexpression may perturb axonal pathfinding and circuit formation in developing DS brain.
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Affiliation(s)
- Lucas J Sosa
- 3Department of Pediatrics, University of Colorado, Mailbox 8313, 12800 E. 19th Ave, Aurora, CO 80045, USA.
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122
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Szemes M, Davies RL, Garden CLP, Usowicz MM. Weaker control of the electrical properties of cerebellar granule cells by tonically active GABAA receptors in the Ts65Dn mouse model of Down's syndrome. Mol Brain 2013; 6:33. [PMID: 23870245 PMCID: PMC3723448 DOI: 10.1186/1756-6606-6-33] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 07/14/2013] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Down's syndrome (DS) is caused by triplication of all or part of human chromosome 21 and is characterized by a decrease in the overall size of the brain. One of the brain regions most affected is the cerebellum, in which the number of granule cells (GCs) is markedly decreased. GCs process sensory information entering the cerebellum via mossy fibres and pass it on to Purkinje cells and inhibitory interneurons. How GCs transform incoming signals depends on their input-output relationship, which is adjusted by tonically active GABA(A) receptor channels. RESULTS We report that in the Ts65Dn mouse model of DS, in which cerebellar volume and GC number are decreased as in DS, the tonic GABA(A) receptor current in GCs is smaller than in wild-type mice and is less effective in moderating input resistance and raising the minimum current required for action potential firing. We also find that tonically active GABA(A) receptors curb the height and broaden the width of action potentials in wild-type GCs but not in Ts65Dn GCs. Single-cell real-time quantitative PCR reveals that these electrical differences are accompanied by decreased expression of the gene encoding the GABA(A) receptor β3 subunit but not genes coding for some of the other GABA(A) receptor subunits expressed in GCs (α1, α6, β2 and δ). CONCLUSIONS Weaker moderation of excitability and action potential waveform in GCs of the Ts65Dn mouse by tonically active GABA(A) receptors is likely to contribute to atypical transfer of information through the cerebellum. Similar changes may occur in DS.
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Affiliation(s)
- Marianna Szemes
- Present address: School of Cellular and Molecular Medicine, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Rachel L Davies
- Present address: Research & Enterprise Development, University of Bristol, Senate House, Tyndall Avenue, Bristol BS8 1TH, UK
| | - Claire LP Garden
- Present address: School of Life, Sport and Social Sciences, Edinburgh Napier University, Sighthill Court, Edinburgh EH11 4BN, UK
| | - Maria M Usowicz
- School of Physiology & Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
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123
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Jiang J, Jing Y, Cost GJ, Chiang JC, Kolpa HJ, Cotton AM, Carone DM, Carone BR, Shivak DA, Guschin DY, Pearl JR, Rebar EJ, Byron M, Gregory PD, Brown CJ, Urnov FD, Hall LL, Lawrence JB. Translating dosage compensation to trisomy 21. Nature 2013; 500:296-300. [PMID: 23863942 PMCID: PMC3848249 DOI: 10.1038/nature12394] [Citation(s) in RCA: 233] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 06/18/2013] [Indexed: 12/21/2022]
Abstract
Down syndrome (DS) is a common disorder with enormous medical and social costs, caused by trisomy for chromosome 21 (Chr21). We tested the concept that gene imbalance across an extra chromosome can be de facto corrected by manipulating a single gene, XIST. Using genome editing with zinc finger nucleases, we targeted a large, inducible XIST transgene into the Chr21 DYRK1A locus, in DS pluripotent stem cells. XIST RNA coats Chr21 and triggers stable heterochromatin modifications, chromosome-wide transcriptional silencing and DNA methylation to form a “Chr21 Barr Body.” This provides a model to study human chromosome inactivation and creates a system to investigate genomic expression changes and cellular pathologies of trisomy 21, free from genetic and epigenetic noise. Remarkably, deficits in proliferation and neural rosette formation are rapidly reversed upon silencing one Chr21. Successful trisomy silencing in vitro also surmounts the major first step towards potential development of “chromosome therapy”.
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Affiliation(s)
- Jun Jiang
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, Massachusetts 01655, USA
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124
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Laguna A, Barallobre MJ, Marchena MÁ, Mateus C, Ramírez E, Martínez-Cue C, Delabar JM, Castelo-Branco M, de la Villa P, Arbonés ML. Triplication of DYRK1A causes retinal structural and functional alterations in Down syndrome. Hum Mol Genet 2013; 22:2775-84. [PMID: 23512985 DOI: 10.1093/hmg/ddt125] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Down syndrome (DS) results from the triplication of approximately 300 human chromosome 21 (Hsa21) genes and affects almost all body organs. Children with DS have defects in visual processing that may have a negative impact on their daily life and cognitive development. However, there is little known about the genes and pathogenesis underlying these defects. Here, we show morphometric in vivo data indicating that the neural retina is thicker in DS individuals than in the normal population. A similar thickening specifically affecting the inner part of the retina was also observed in a trisomic model of DS, the Ts65Dn mouse. Increased retinal size and cellularity in this model correlated with abnormal retinal function and resulted from an impaired caspase-9-mediated apoptosis during development. Moreover, we show that mice bearing only one additional copy of Dyrk1a have the same retinal phenotype as Ts65Dn mice and normalization of Dyrk1a gene copy number in Ts65Dn mice completely rescues both, morphological and functional phenotypes. Thus, triplication of Dyrk1a is necessary and sufficient to cause the retinal phenotype described in the trisomic model. Our data demonstrate for the first time the implication of DYRK1A overexpression in a developmental alteration of the central nervous system associated with DS, thereby providing insights into the aetiology of neurosensorial dysfunction in a complex disease.
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Affiliation(s)
- Ariadna Laguna
- Department of Developmental Biology, Institut de Biologia Molecular de Barcelona IBMB-CSIC, Barcelona 08028, Spain
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125
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Imai M, Watanabe H, Yasui K, Kimura Y, Shitara Y, Tsuchida S, Takahashi N, Taga G. Functional connectivity of the cortex of term and preterm infants and infants with Down's syndrome. Neuroimage 2013; 85 Pt 1:272-8. [PMID: 23631984 DOI: 10.1016/j.neuroimage.2013.04.080] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/15/2013] [Accepted: 04/18/2013] [Indexed: 10/26/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) imaging studies have revealed the functional development of the human brain in early infancy. By measuring spontaneous fluctuations in cerebral blood oxygenation with NIRS, we can examine the developmental status of the functional connectivity of networks in the cortex. However, it has not been clarified whether premature delivery and/or chromosomal abnormalities affect the development of the functional connectivity of the cortex. In the current study, we investigated the spontaneous brain activity of sleeping infants who were admitted to a neonatal intensive care unit at term age. We classified them into the 3 following infant groups: (i) term-or-late-preterm, (ii) early-preterm, and (iii) Down's syndrome (DS). We used multichannel NIRS to measure the spontaneous changes in oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) at 10 measurement channels, which covered the frontal, temporal, and occipital regions. In order to reveal the functional connectivity of the cortical networks, we calculated the temporal correlations of the time-course signals among all of the pairs of measurement channels. The functional connectivity was classified into the 4 following types: (i) short-range, (ii) contralateral-transverse, (iii) ipsilateral-longitudinal, and (iv) control. In order to examine whether the local properties of hemodynamics reflected any pathological conditions, we calculated the phase differences between the oxy- and deoxy-Hb time-course signals in the 3 groups. The statistical analyses of the functional connectivity data showed main effects of group and the types of connectivity. For the group effect, the mean functional connectivity of the infants in the term-or-late-preterm group did not differ from that in the early-preterm group, and the mean functional connectivity of the infants in the DS group was lower than that in the other 2 groups. For the effect of types of connectivity, short-range connectivity was highest compared to any of the other types of connectivity, and the second highest connectivity was the contralateral-transverse one. The phase differences between the oxy- and deoxy-Hb changes showed that there were significant differences between the DS group and the other 2 groups. Our findings suggested that the development of the functional connectivity of cortical networks did not differ between term-or-late-preterm infants and early-preterm infants around term-equivalent ages, while DS infants had alterations in their functional connectivity development and local hemodynamics at term age. The highest short-range connectivity and the second highest contralateral-transverse connectivity suggested that the precursors for the basic cortical networks of functional connectivity were present at term age.
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Affiliation(s)
- Makiko Imai
- Graduate School of Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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126
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Briggs JA, Mason EA, Ovchinnikov DA, Wells CA, Wolvetang EJ. Concise review: new paradigms for Down syndrome research using induced pluripotent stem cells: tackling complex human genetic disease. Stem Cells Transl Med 2013; 2:175-84. [PMID: 23413375 DOI: 10.5966/sctm.2012-0117] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Down syndrome (DS) is a complex developmental disorder with diverse pathologies that affect multiple tissues and organ systems. Clear mechanistic description of how trisomy of chromosome 21 gives rise to most DS pathologies is currently lacking and is limited to a few examples of dosage-sensitive trisomic genes with large phenotypic effects. The recent advent of cellular reprogramming technology offers a promising way forward, by allowing derivation of patient-derived human cell types in vitro. We present general strategies that integrate genomics technologies and induced pluripotent stem cells to identify molecular networks driving different aspects of DS pathogenesis and describe experimental approaches to validate the causal requirement of candidate network defects for particular cellular phenotypes. This overall approach should be applicable to many poorly understood complex human genetic diseases, whose pathogenic mechanisms might involve the combined effects of many genes.
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Affiliation(s)
- James A Briggs
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, St Lucia, Queensland, Australia
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127
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Separated at birth? The functional and molecular divergence of OLIG1 and OLIG2. Nat Rev Neurosci 2013; 13:819-31. [PMID: 23165259 DOI: 10.1038/nrn3386] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The basic helix-loop-helix transcription factors oligodendrocyte transcription factor 1 (OLIG1) and OLIG2 are structurally similar and, to a first approximation, coordinately expressed in the developing CNS and postnatal brain. Despite these similarities, it was apparent from early on after their discovery that OLIG1 and OLIG2 have non-overlapping developmental functions in patterning, neuron subtype specification and the formation of oligodendrocytes. Here, we summarize more recent insights into the separate roles of these transcription factors in the postnatal brain during repair processes and in neurological disease states, including multiple sclerosis and malignant glioma. We discuss how the unique functions of OLIG1 and OLIG2 may reflect their distinct genetic targets, co-regulator proteins and/or post-translational modifications.
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128
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Abstract
Down syndrome is the most common form of intellectual disability and results from one of the most complex genetic perturbations that is compatible with survival, trisomy 21. The study of brain dysfunction in this disorder has largely been based on a gene discovery approach, but we are now moving into an era of functional genome exploration, in which the effects of individual genes are being studied alongside the effects of deregulated non-coding genetic elements and epigenetic influences. Also, new data from functional neuroimaging studies are challenging our views of the cognitive phenotypes associated with Down syndrome and their pathophysiological correlates. These advances hold promise for the development of treatments for intellectual disability.
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Affiliation(s)
- Mara Dierssen
- Genes and Disease Programme, Centre for Genomic Regulation (CRG), Universitat Pompeu Fabra, Centro de Investigación Biomédica en Red de Enfermedades Raras, E-08003 Barcelona, Spain.
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Millan MJ. An epigenetic framework for neurodevelopmental disorders: from pathogenesis to potential therapy. Neuropharmacology 2012; 68:2-82. [PMID: 23246909 DOI: 10.1016/j.neuropharm.2012.11.015] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 11/11/2012] [Accepted: 11/22/2012] [Indexed: 12/12/2022]
Abstract
Neurodevelopmental disorders (NDDs) are characterized by aberrant and delayed early-life development of the brain, leading to deficits in language, cognition, motor behaviour and other functional domains, often accompanied by somatic symptoms. Environmental factors like perinatal infection, malnutrition and trauma can increase the risk of the heterogeneous, multifactorial and polygenic disorders, autism and schizophrenia. Conversely, discrete genetic anomalies are involved in Down, Rett and Fragile X syndromes, tuberous sclerosis and neurofibromatosis, the less familiar Phelan-McDermid, Sotos, Kleefstra, Coffin-Lowry and "ATRX" syndromes, and the disorders of imprinting, Angelman and Prader-Willi syndromes. NDDs have been termed "synaptopathies" in reference to structural and functional disturbance of synaptic plasticity, several involve abnormal Ras-Kinase signalling ("rasopathies"), and many are characterized by disrupted cerebral connectivity and an imbalance between excitatory and inhibitory transmission. However, at a different level of integration, NDDs are accompanied by aberrant "epigenetic" regulation of processes critical for normal and orderly development of the brain. Epigenetics refers to potentially-heritable (by mitosis and/or meiosis) mechanisms controlling gene expression without changes in DNA sequence. In certain NDDs, prototypical epigenetic processes of DNA methylation and covalent histone marking are impacted. Conversely, others involve anomalies in chromatin-modelling, mRNA splicing/editing, mRNA translation, ribosome biogenesis and/or the regulatory actions of small nucleolar RNAs and micro-RNAs. Since epigenetic mechanisms are modifiable, this raises the hope of novel therapy, though questions remain concerning efficacy and safety. The above issues are critically surveyed in this review, which advocates a broad-based epigenetic framework for understanding and ultimately treating a diverse assemblage of NDDs ("epigenopathies") lying at the interface of genetic, developmental and environmental processes. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Mark J Millan
- Unit for Research and Discovery in Neuroscience, IDR Servier, 125 chemin de ronde, 78290 Croissy sur Seine, Paris, France.
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130
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Ruparelia A, Pearn ML, Mobley WC. Cognitive and pharmacological insights from the Ts65Dn mouse model of Down syndrome. Curr Opin Neurobiol 2012; 22:880-6. [PMID: 22658745 PMCID: PMC3434300 DOI: 10.1016/j.conb.2012.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 05/03/2012] [Indexed: 02/06/2023]
Abstract
Down syndrome (DS) is a multi-faceted condition resulting in the most common genetic form of intellectual disability. Mouse models of DS, especially the Ts65Dn model, have been pivotal in furthering our understanding of the genetic, molecular and neurobiological mechanisms that underlie learning and memory impairments in DS. Cognitive and pharmacological insights from the Ts65Dn mouse model have led to remarkable translational progress in the development of therapeutic targets and in the emergence of DS clinical trials. Unravelling the pathogenic role of trisomic genes on human chromosome 21 and the genotype-phenotype relationship still remains a pertinent goal for tackling cognitive deficits in DS.
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Affiliation(s)
- Aarti Ruparelia
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London, WC1N 3BG, UK
| | - Matthew L Pearn
- Department of Anaesthesiology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, 3350 La Jolla Village Drive 9125, San Diego, CA 92161-9125, USA
| | - William C Mobley
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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131
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Deficits in cognition and synaptic plasticity in a mouse model of Down syndrome ameliorated by GABAB receptor antagonists. J Neurosci 2012; 32:9217-27. [PMID: 22764230 DOI: 10.1523/jneurosci.1673-12.2012] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cognitive impairment in Down syndrome (DS) is characterized by deficient learning and memory. Mouse genetic models of DS exhibit impaired cognition in hippocampally mediated behavioral tasks and reduced synaptic plasticity of hippocampal pathways. Enhanced efficiency of GABAergic neurotransmission was implicated in those changes. We have recently shown that signaling through postsynaptic GABA(B) receptors is significantly increased in the dentate gyrus of Ts65Dn mice, a genetic model of DS. Here we examined a role for GABA(B) receptors in cognitive deficits in DS by defining the effect of selective GABA(B) receptor antagonists on behavior and synaptic plasticity of adult Ts65Dn mice. Treatment with the GABA(B) receptor antagonist CGP55845 restored memory of Ts65Dn mice in the novel place recognition, novel object recognition, and contextual fear conditioning tasks, but did not affect locomotion and performance in T-maze. The treatment increased hippocampal levels of brain-derived neurotrophic factor, equally in 2N and Ts65Dn mice. In hippocampal slices, treatment with the GABA(B) receptor antagonists CGP55845 or CGP52432 enhanced long-term potentiation (LTP) in the Ts65Dn DG. The enhancement of LTP was accompanied by an increase in the NMDA receptor-mediated component of the tetanus-evoked responses. These findings are evidence for a contribution of GABA(B) receptors to changes in hippocampal-based cognition in the Ts65Dn mouse. The ability to rescue cognitive performance through treatment with selective GABA(B) receptor antagonists motivates studies to further explore the therapeutic potential of these compounds in people with DS.
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132
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Möhler H. Cognitive enhancement by pharmacological and behavioral interventions: the murine Down syndrome model. Biochem Pharmacol 2012; 84:994-9. [PMID: 22898099 DOI: 10.1016/j.bcp.2012.06.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 06/29/2012] [Accepted: 06/29/2012] [Indexed: 12/26/2022]
Abstract
The cognitive deficits in Down syndrome (DS) are attributed to an excessive hippocampal inhibition, which obstructs neuronal plasticity and normal learning and memory, a view which is largely based on studies of Ts65Dn mice, the best characterized mouse model of DS. The cognitive behavioral deficits of Ts65Dn mice can be rescued by reducing GABAergic inhibition, most selectively by partial inverse agonists acting on α(5) GABA-A receptors, of which one compound has recently entered clinical trials in DS. Most remarkably, the improved cognitive performance of Ts65Dn can persist for weeks and months after cessation of drug treatment, as demonstrated for the non-specific GABA antagonist pentylenetetrazole. The Alzheimer drugs, memantine and donepezil largely fail to show any benefit. Finally, repeated non-invasive sensory stimulation such as over-training or enriching the environment, are able to enhance the learning performance which underlines the reversibility of an obstructed neuronal plasticity in Ts65Dn mice.
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Affiliation(s)
- Hanns Möhler
- Institute of Pharmacology, University of Zurich and, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
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133
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From abnormal hippocampal synaptic plasticity in down syndrome mouse models to cognitive disability in down syndrome. Neural Plast 2012; 2012:101542. [PMID: 22848844 PMCID: PMC3403629 DOI: 10.1155/2012/101542] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/02/2012] [Accepted: 05/07/2012] [Indexed: 12/17/2022] Open
Abstract
Down syndrome (DS) is caused by the overexpression of genes on triplicated regions of human chromosome 21 (Hsa21). While the resulting physiological and behavioral phenotypes vary in their penetrance and severity, all individuals with DS have variable but significant levels of cognitive disability. At the core of cognitive processes is the phenomenon of synaptic plasticity, a functional change in the strength at points of communication between neurons. A wide variety of evidence from studies on DS individuals and mouse models of DS indicates that synaptic plasticity is adversely affected in human trisomy 21 and mouse segmental trisomy 16, respectively, an outcome that almost certainly extensively contributes to the cognitive impairments associated with DS. In this review, we will highlight some of the neurophysiological changes that we believe reduce the ability of trisomic neurons to undergo neuroplasticity-related adaptations. We will focus primarily on hippocampal networks which appear to be particularly impacted in DS and where consequently the majority of cellular and neuronal network research has been performed using DS animal models, in particular the Ts65Dn mouse. Finally, we will postulate on how altered plasticity may contribute to the DS cognitive disability.
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134
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Lack of behavioral and cognitive effects of chronic ethosuximide and gabapentin treatment in the Ts65Dn mouse model of Down syndrome. Neuroscience 2012; 220:158-68. [PMID: 22728103 DOI: 10.1016/j.neuroscience.2012.06.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 06/06/2012] [Accepted: 06/13/2012] [Indexed: 11/22/2022]
Abstract
The Ts65Dn (TS) mouse model of Down syndrome (DS) displays a number of behavioral, neuromorphological and neurochemical phenotypes of the syndrome. Altered GABAergic transmission appears to contribute to the mechanisms responsible for the cognitive impairments in TS mice. Increased functional expression of the trisomic gene encoding an inwardly rectifying potassium channel, subfamily J, member 6 (KCNJ6) has been reported in DS and TS mice, along with the consequent impairment in GAB Aergic function. Partial display of DS phenotypes in mice harboring a single trisomy of Kcnj6 provides compelling evidence for a functional role of increased channel expression in some of the abnormal neurological phenotypes found in DS. Notably, the antiepileptic drug (AED) ethosuximide (ETH), but not other AEDs such as gabapentin (GAB), is known to inhibit KCNJ6 channels in mice. Here, we report the effect of chronic ETH and GAB on the behavioral and cognitive phenotypes of TS and disomic control (CO) mice. Neither drug significantly affected sensorimotor abilities, motor coordination or spontaneous activity in TS and CO mice. Also, ETH and GAB did not induce anxiety in the open field or plus maze tests, did not alter performance in the Morris water maze, and did not affect cued - or context - fear conditioning. Our results thus suggest that KCNJ6 may not be a promising drug target candidate in DS. As a corollary, they also show that long-term use of ETH and GAB is devoid of adverse behavioral and cognitive effects.
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135
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Increased excitability and altered action potential waveform in cerebellar granule neurons of the Ts65Dn mouse model of Down syndrome. Brain Res 2012; 1465:10-7. [PMID: 22627164 PMCID: PMC3389345 DOI: 10.1016/j.brainres.2012.05.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/09/2012] [Accepted: 05/14/2012] [Indexed: 12/19/2022]
Abstract
Down syndrome (DS) is characterized by intellectual disability and impaired motor control. Lack of coordinated movement, poor balance, and unclear speech imply dysfunction of the cerebellum, which is known to be reduced in volume in DS. The principal cause of the smaller cerebellum is a diminished number of granule cells (GCs). These neurons form the ‘input layer’ of the cerebellar cortex, where sensorimotor information carried by incoming mossy fibers is transformed before it is conveyed to Purkinje cells and inhibitory interneurons. However, it is not known how processing of this information is affected in the hypogranular cerebellum that characterizes DS. Here we explore the possibility that the electrical properties of the surviving GCs are changed. We find that in the Ts65Dn mouse model of DS, GCs have a higher input resistance at voltages approaching the threshold for firing, which causes them to be more excitable. In addition, they fire narrower and larger amplitude action potentials. These subtly modified electrical properties may result in atypical transfer of information at the input layer of the cerebellum.
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136
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Currier DG, Polk RC, Reeves RH. A Sonic hedgehog (Shh) response deficit in trisomic cells may be a common denominator for multiple features of Down syndrome. PROGRESS IN BRAIN RESEARCH 2012; 197:223-36. [PMID: 22541295 PMCID: PMC4405118 DOI: 10.1016/b978-0-444-54299-1.00011-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The hedgehog (HH) family of growth factors is involved in many aspects of growth and development, from the establishment of left-right axes at gastrulation to the patterning and formation of multiple structures in essentially every tissue, to the maintenance and regulation of stem cell populations in adults. Sonic hedgehog (Shh) in particular acts as a mitogen, regulating proliferation of target cells, a growth factor that triggers differentiation in target populations, and a morphogen causing cells to respond differently based on their positions along a spatial and temporal concentration gradient. Given its very broad range of effects in development, it is not surprising that many of the structures affected by a disruption in Shh signaling are also affected in Down syndrome (DS). However, recent studies have shown that trisomic cerebellar granule cell precursors have a deficit, compared to their euploid counterparts, in their response to the mitogenic effects of Shh. This deficit substantially contributes to the hypocellular cerebellum in mouse models that parallels the human DS phenotype and can be corrected in early development by a single exposure to a small-molecule agonist of the Shh pathway. Here, we consider how an attenuated Shh response might affect several aspects of development to produce multiple phenotypic outcomes observed in DS.
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Affiliation(s)
- Duane G. Currier
- Department of Physiology and The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Renita C. Polk
- Department of Physiology and The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Roger H. Reeves
- Department of Physiology and The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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137
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de la Torre R, Dierssen M. Therapeutic approaches in the improvement of cognitive performance in Down syndrome. PROGRESS IN BRAIN RESEARCH 2012; 197:1-14. [DOI: 10.1016/b978-0-444-54299-1.00001-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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