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Bartesaghi R. Brain circuit pathology in Down syndrome: from neurons to neural networks. Rev Neurosci 2022; 34:365-423. [PMID: 36170842 DOI: 10.1515/revneuro-2022-0067] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/28/2022] [Indexed: 11/15/2022]
Abstract
Down syndrome (DS), a genetic pathology caused by triplication of chromosome 21, is characterized by brain hypotrophy and impairment of cognition starting from infancy. While studies in mouse models of DS have elucidated the major neuroanatomical and neurochemical defects of DS, comparatively fewer investigations have focused on the electrophysiology of the DS brain. Electrical activity is at the basis of brain functioning. Therefore, knowledge of the way in which brain circuits operate in DS is fundamental to understand the causes of behavioral impairment and devise targeted interventions. This review summarizes the state of the art regarding the electrical properties of the DS brain, starting from individual neurons and culminating in signal processing in whole neuronal networks. The reported evidence derives from mouse models of DS and from brain tissues and neurons derived from individuals with DS. EEG data recorded in individuals with DS are also provided as a key tool to understand the impact of brain circuit alterations on global brain activity.
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Affiliation(s)
- Renata Bartesaghi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy
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2
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Panagaki T, Lozano-Montes L, Janickova L, Zuhra K, Szabo MP, Majtan T, Rainer G, Maréchal D, Herault Y, Szabo C. Overproduction of hydrogen sulfide, generated by cystathionine β-synthase, disrupts brain wave patterns and contributes to neurobehavioral dysfunction in a rat model of down syndrome. Redox Biol 2022; 51:102233. [PMID: 35042677 PMCID: PMC9039679 DOI: 10.1016/j.redox.2022.102233] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/26/2021] [Accepted: 01/10/2022] [Indexed: 12/23/2022] Open
Abstract
Using a novel rat model of Down syndrome (DS), the functional role of the cystathionine-β-synthase (CBS)/hydrogen sulfide (H2S) pathway was investigated on the pathogenesis of brain wave pattern alterations and neurobehavioral dysfunction. Increased expression of CBS and subsequent overproduction of H2S was observed in the brain of DS rats, with CBS primarily localizing to astrocytes and the vasculature. DS rats exhibited neurobehavioral defects, accompanied by a loss of gamma brain wave activity and a suppression of the expression of multiple pre- and postsynaptic proteins. Aminooxyacetate, a prototypical pharmacological inhibitor of CBS, increased the ability of the DS brain tissue to generate ATP in vitro and reversed the electrophysiological and neurobehavioral alterations in vivo. Thus, the CBS/H2S pathway contributes to the pathogenesis of neurological dysfunction in DS, most likely through dysregulation of cellular bioenergetics and gene expression.
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Affiliation(s)
- Theodora Panagaki
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Laura Lozano-Montes
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland; Visual Cognition Laboratory, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Lucia Janickova
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Karim Zuhra
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Marcell P Szabo
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Tomas Majtan
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Gregor Rainer
- Visual Cognition Laboratory, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Damien Maréchal
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
| | - Yann Herault
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
| | - Csaba Szabo
- Chair of Pharmacology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland.
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Ginsberg SD, Joshi S, Sharma S, Guzman G, Wang T, Arancio O, Chiosis G. The penalty of stress - Epichaperomes negatively reshaping the brain in neurodegenerative disorders. J Neurochem 2021; 159:958-979. [PMID: 34657288 PMCID: PMC8688321 DOI: 10.1111/jnc.15525] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/22/2021] [Accepted: 10/13/2021] [Indexed: 02/06/2023]
Abstract
Adaptation to acute and chronic stress and/or persistent stressors is a subject of wide interest in central nervous system disorders. In this context, stress is an effector of change in organismal homeostasis and the response is generated when the brain perceives a potential threat. Herein, we discuss a nuanced and granular view whereby a wide variety of genotoxic and environmental stressors, including aging, genetic risk factors, environmental exposures, and age- and lifestyle-related changes, act as direct insults to cellular, as opposed to organismal, homeostasis. These two concepts of how stressors impact the central nervous system are not mutually exclusive. We discuss how maladaptive stressor-induced changes in protein connectivity through epichaperomes, disease-associated pathologic scaffolds composed of tightly bound chaperones, co-chaperones, and other factors, impact intracellular protein functionality altering phenotypes, that in turn disrupt and remodel brain networks ranging from intercellular to brain connectome levels. We provide an evidence-based view on how these maladaptive changes ranging from stressor to phenotype provide unique precision medicine opportunities for diagnostic and therapeutic development, especially in the context of neurodegenerative disorders including Alzheimer's disease where treatment options are currently limited.
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Affiliation(s)
- Stephen D. Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York, USA
- Departments of Psychiatry, Neuroscience & Physiology, the NYU Neuroscience Institute, New York University Grossman School of Medicine, New York City, New York, USA
| | - Suhasini Joshi
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | - Sahil Sharma
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | - Gianny Guzman
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | - Tai Wang
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
| | - Ottavio Arancio
- Department of Pathology and Cell Biology, Columbia University, New York City, New York, USA
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University, New York City, New York, USA
| | - Gabriela Chiosis
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York City, New York, USA
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4
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5
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Ponroy Bally B, Farmer WT, Jones EV, Jessa S, Kacerovsky JB, Mayran A, Peng H, Lefebvre JL, Drouin J, Hayer A, Ernst C, Murai KK. Human iPSC-derived Down syndrome astrocytes display genome-wide perturbations in gene expression, an altered adhesion profile, and increased cellular dynamics. Hum Mol Genet 2020; 29:785-802. [PMID: 31943018 PMCID: PMC7104679 DOI: 10.1093/hmg/ddaa003] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/31/2019] [Accepted: 01/10/2020] [Indexed: 12/15/2022] Open
Abstract
Down syndrome (DS), caused by the triplication of human chromosome 21, leads to significant alterations in brain development and is a major genetic cause of intellectual disability. While much is known about changes to neurons in DS, the effects of trisomy 21 on non-neuronal cells such as astrocytes are poorly understood. Astrocytes are critical for brain development and function, and their alteration may contribute to DS pathophysiology. To better understand the impact of trisomy 21 on astrocytes, we performed RNA-sequencing on astrocytes from newly produced DS human induced pluripotent stem cells (hiPSCs). While chromosome 21 genes were upregulated in DS astrocytes, we found consistent up- and down-regulation of genes across the genome with a strong dysregulation of neurodevelopmental, cell adhesion and extracellular matrix molecules. ATAC (assay for transposase-accessible chromatin)-seq also revealed a global alteration in chromatin state in DS astrocytes, showing modified chromatin accessibility at promoters of cell adhesion and extracellular matrix genes. Along with these transcriptomic and epigenomic changes, DS astrocytes displayed perturbations in cell size and cell spreading as well as modifications to cell-cell and cell-substrate recognition/adhesion, and increases in cellular motility and dynamics. Thus, triplication of chromosome 21 is associated with genome-wide transcriptional, epigenomic and functional alterations in astrocytes that may contribute to altered brain development and function in DS.
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Affiliation(s)
- Blandine Ponroy Bally
- Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, QC H3G 1A4, Canada
| | - W Todd Farmer
- Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, QC H3G 1A4, Canada
| | - Emma V Jones
- Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, QC H3G 1A4, Canada
| | - Selin Jessa
- Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, QC H3G 1A4, Canada
- Quantitative Life Sciences, McGill University, Montreal, QC H3A 2A7, Canada
| | - J Benjamin Kacerovsky
- Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, QC H3G 1A4, Canada
| | - Alexandre Mayran
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Huashan Peng
- Department of Psychiatry, McGill University, Montreal, QC H4H 1R3, Canada
- Department of Human Genetics, McGill University, Montreal, QC H4H 1R3, Canada
- Douglas Hospital Research Institute, Verdun, QC H4H 1R3, Canada
| | - Julie L Lefebvre
- Department of Molecular Genetics, Program for Neuroscience and Mental Health, Hospital for Sick Children, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Jacques Drouin
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Arnold Hayer
- Department of Biology, McGill University, Bellini Life Sciences Complex, Montreal, QC H3G 0B1, Canada
| | - Carl Ernst
- Department of Psychiatry, McGill University, Montreal, QC H4H 1R3, Canada
- Department of Human Genetics, McGill University, Montreal, QC H4H 1R3, Canada
- Douglas Hospital Research Institute, Verdun, QC H4H 1R3, Canada
| | - Keith K Murai
- Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal, QC H3G 1A4, Canada
- Quantitative Life Sciences, McGill University, Montreal, QC H3A 2A7, Canada
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NEXMIF/KIDLIA Knock-out Mouse Demonstrates Autism-Like Behaviors, Memory Deficits, and Impairments in Synapse Formation and Function. J Neurosci 2019; 40:237-254. [PMID: 31704787 DOI: 10.1523/jneurosci.0222-19.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 10/31/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disability that demonstrates impaired social interactions, communication deficits, and restrictive and repetitive behaviors. ASD has a strong genetic basis and many ASD-associated genes have been discovered thus far. Our previous work has shown that loss of expression of the X-linked gene NEXMIF/KIDLIA is implicated in patients with autistic features and intellectual disability (ID). To further determine the causal role of the gene in the disorder, and to understand the cellular and molecular mechanisms underlying the pathology, we have generated a NEXMIF knock-out (KO) mouse. We find that male NEXMIF KO mice demonstrate reduced sociability and communication, elevated repetitive grooming behavior, and deficits in learning and memory. Loss of NEXMIF/KIDLIA expression results in a significant decrease in synapse density and synaptic protein expression. Consistently, male KO animals show aberrant synaptic function as measured by excitatory miniatures and postsynaptic currents in the hippocampus. These findings indicate that NEXMIF KO mice recapitulate the phenotypes of the human disorder. The NEXMIF KO mouse model will be a valuable tool for studying the complex mechanisms involved in ASD and for the development of novel therapeutics for this disorder.SIGNIFICANCE STATEMENT Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by behavioral phenotypes. Based on our previous work, which indicated the loss of NEXMIF/KIDLIA was associated with ASD, we generated NEXMIF knock-out (KO) mice. The NEXMIF KO mice demonstrate autism-like behaviors including deficits in social interaction, increased repetitive self-grooming, and impairments in communication and in learning and memory. The KO neurons show reduced synapse density and a suppression in synaptic transmission, indicating a role for NEXMIF in regulating synapse development and function. The NEXMIF KO mouse faithfully recapitulates the human disorder, and thus serves as an animal model for future investigation of the NEXMIF-dependent neurodevelopmental disorders.
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Zhao X, Bhattacharyya A. Human Models Are Needed for Studying Human Neurodevelopmental Disorders. Am J Hum Genet 2018; 103:829-857. [PMID: 30526865 DOI: 10.1016/j.ajhg.2018.10.009] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 10/09/2018] [Indexed: 12/19/2022] Open
Abstract
The analysis of animal models of neurological disease has been instrumental in furthering our understanding of neurodevelopment and brain diseases. However, animal models are limited in revealing some of the most fundamental aspects of development, genetics, pathology, and disease mechanisms that are unique to humans. These shortcomings are exaggerated in disorders that affect the brain, where the most significant differences between humans and animal models exist, and could underscore failures in targeted therapeutic interventions in affected individuals. Human pluripotent stem cells have emerged as a much-needed model system for investigating human-specific biology and disease mechanisms. However, questions remain regarding whether these cell-culture-based models are sufficient or even necessary. In this review, we summarize human-specific features of neurodevelopment and the most common neurodevelopmental disorders, present discrepancies between animal models and human diseases, demonstrate how human stem cell models can provide meaningful information, and discuss the challenges that exist in our pursuit to understand distinctively human aspects of neurodevelopment and brain disease. This information argues for a more thoughtful approach to disease modeling through consideration of the valuable features and limitations of each model system, be they human or animal, to mimic disease characteristics.
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Affiliation(s)
- Xinyu Zhao
- Waisman Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI 53705, USA; Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI 53705, USA.
| | - Anita Bhattacharyya
- Waisman Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI 53705, USA; Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI 53705, USA.
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8
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De Giorgio A. The roles of motor activity and environmental enrichment in intellectual disability. Somatosens Mot Res 2017; 34:34-43. [PMID: 28140743 DOI: 10.1080/08990220.2016.1278204] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In people with intellectual disabilities, an enriched environment can stimulate the acquisition of motor skills and could partially repair neuronal impairment thanks to exploration and motor activity. A deficit in environmental and motor stimulation leads to low scores in intelligence tests and can cause serious motor skill problems. Although studies in humans do not give much evidence for explaining basic mechanisms of intellectual disability and for highlighting improvements due to enriched environmental stimulation, animal models have been valuable in the investigation of these conditions. Here, we discuss the role of environmental enrichment in four intellectual disabilities: Foetal Alcohol Spectrum Disorder (FASD), Down, Rett, and Fragile X syndromes.
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Affiliation(s)
- Andrea De Giorgio
- a Department of Psychology , eCampus University , Novedrate , Italy.,b Department of Psychology , Universita Cattolica del Sacro Cuore , Milano , Italy
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9
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Peng C, Hong X, Chen W, Zhang H, Tan L, Wang X, Ding Y, He J. Melatonin ameliorates amygdala-dependent emotional memory deficits in Tg2576 mice by up-regulating the CREB/c-Fos pathway. Neurosci Lett 2017; 638:76-82. [DOI: 10.1016/j.neulet.2016.11.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/04/2016] [Accepted: 11/29/2016] [Indexed: 12/13/2022]
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10
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The X-Linked Autism Protein KIAA2022/KIDLIA Regulates Neurite Outgrowth via N-Cadherin and δ-Catenin Signaling. eNeuro 2016; 3:eN-NWR-0238-16. [PMID: 27822498 PMCID: PMC5083950 DOI: 10.1523/eneuro.0238-16.2016] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/21/2016] [Accepted: 10/14/2016] [Indexed: 12/26/2022] Open
Abstract
Our previous work showed that loss of the KIAA2022 gene protein results in intellectual disability with language impairment and autistic behavior (KIDLIA, also referred to as XPN). However, the cellular and molecular alterations resulting from a loss of function of KIDLIA and its role in autism with severe intellectual disability remain unknown. Here, we show that KIDLIA plays a key role in neuron migration and morphogenesis. We found that KIDLIA is distributed exclusively in the nucleus. In the developing rat brain, it is expressed only in the cortical plate and subplate region but not in the intermediate or ventricular zone. Using in utero electroporation, we found that short hairpin RNA (shRNA)-mediated knockdown of KIDLIA leads to altered neuron migration and a reduction in dendritic growth and disorganized apical dendrite projections in layer II/III mouse cortical neurons. Consistent with this, in cultured rat neurons, a loss of KIDLIA expression also leads to suppression of dendritic growth and branching. At the molecular level, we found that KIDLIA suppression leads to an increase in cell-surface N-cadherin and an elevated association of N-cadherin with δ-catenin, resulting in depletion of free δ-catenin in the cytosolic compartment. The reduced availability of cytosolic δ-catenin leads to elevated RhoA activity and reduced actin dynamics at the dendritic growth cone. Furthermore, in neurons with KIDLIA knockdown, overexpression of δ-catenin or inhibition of RhoA rescues actin dynamics, dendritic growth, and branching. These findings provide the first evidence on the role of the novel protein KIDLIA in neurodevelopment and autism with severe intellectual disability.
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11
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Tramutola A, Lanzillotta C, Di Domenico F. Targeting mTOR to reduce Alzheimer-related cognitive decline: from current hits to future therapies. Expert Rev Neurother 2016; 17:33-45. [PMID: 27690737 DOI: 10.1080/14737175.2017.1244482] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION The mTOR pathway is involved in the regulation of a wide repertoire of cellular functions in the brain and its dysregulation is emerging as a leitmotif in a large number of neurological disorders. In AD, altered mTOR signaling contributes to the inhibition of autophagy deposition of Aβ and tau aggregates and to the alteration of several neuronal metabolic pathways. Areas covered: In this review, we report all the current findings on the use of mTOR inhibitors (rapamycin, rapalogues) in the treatment of AD. These results support the role of mTOR inhibitors as potential therapeutic agents able to reduce AD hallmarks and recover cognitive performances. Expert commentary: Despite mTOR inhibitors appearing to be ideal compounds to counteract AD, further studies are needed in order to gain knowledge on the involvement of aberrant mTOR in AD, and to standardize a valuable therapeutic approach that can be translated to humans.
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Affiliation(s)
- Antonella Tramutola
- a Department of Biochemical Sciences , Sapienza University of Rome , Rome , Italy
| | - Chiara Lanzillotta
- a Department of Biochemical Sciences , Sapienza University of Rome , Rome , Italy
| | - Fabio Di Domenico
- a Department of Biochemical Sciences , Sapienza University of Rome , Rome , Italy
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Lepeta K, Lourenco MV, Schweitzer BC, Martino Adami PV, Banerjee P, Catuara-Solarz S, de La Fuente Revenga M, Guillem AM, Haidar M, Ijomone OM, Nadorp B, Qi L, Perera ND, Refsgaard LK, Reid KM, Sabbar M, Sahoo A, Schaefer N, Sheean RK, Suska A, Verma R, Vicidomini C, Wright D, Zhang XD, Seidenbecher C. Synaptopathies: synaptic dysfunction in neurological disorders - A review from students to students. J Neurochem 2016; 138:785-805. [PMID: 27333343 PMCID: PMC5095804 DOI: 10.1111/jnc.13713] [Citation(s) in RCA: 216] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/03/2016] [Accepted: 06/06/2016] [Indexed: 12/12/2022]
Abstract
Synapses are essential components of neurons and allow information to travel coordinately throughout the nervous system to adjust behavior to environmental stimuli and to control body functions, memories, and emotions. Thus, optimal synaptic communication is required for proper brain physiology, and slight perturbations of synapse function can lead to brain disorders. In fact, increasing evidence has demonstrated the relevance of synapse dysfunction as a major determinant of many neurological diseases. This notion has led to the concept of synaptopathies as brain diseases with synapse defects as shared pathogenic features. In this review, which was initiated at the 13th International Society for Neurochemistry Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental disorders (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer and Parkinson disease). We finally discuss the appropriateness and potential implications of gathering synapse diseases under a single term. Understanding common causes and intrinsic differences in disease-associated synaptic dysfunction could offer novel clues toward synapse-based therapeutic intervention for neurological and neuropsychiatric disorders. In this Review, which was initiated at the 13th International Society for Neurochemistry (ISN) Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer's and Parkinson's diseases), gathered together under the term of synaptopathies. Read the Editorial Highlight for this article on page 783.
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Affiliation(s)
- Katarzyna Lepeta
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Mychael V Lourenco
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Barbara C Schweitzer
- Department for Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology Magdeburg, Magdeburg, Germany
| | - Pamela V Martino Adami
- Laboratory of Amyloidosis and Neurodegeneration, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina
| | - Priyanjalee Banerjee
- Department of Biochemistry, Institute of Post Graduate Medical Education & Research, Kolkata, West Bengal, India
| | - Silvina Catuara-Solarz
- Systems Biology Program, Cellular and Systems Neurobiology, Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Mario de La Fuente Revenga
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, United States of America
| | - Alain Marc Guillem
- Laboratorio de Neurotoxicología, Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México D.F. 07000, Mexico
| | - Mouna Haidar
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Omamuyovwi M Ijomone
- Department of Human Anatomy, Cross River University of Technology, Okuku Campus, Cross River, Nigeria
| | - Bettina Nadorp
- The Department of Biological Chemistry, The Edmond and Lily Safra Center for Brain Sciences, The Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Israel
| | - Lin Qi
- Laboratory of Molecular Neuro-Oncology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, United States of America
| | - Nirma D Perera
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Louise K Refsgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Kimberley M Reid
- Department of Pharmacology, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
| | - Mariam Sabbar
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Arghyadip Sahoo
- Department of Biochemistry, Midnapore Medical College, West Bengal University of Health Sciences, West Bengal, India
| | - Natascha Schaefer
- Institute for Clinical Neurobiology, Julius-Maximilians-University of Wuerzburg, Wuerzburg, Germany
| | - Rebecca K Sheean
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Anna Suska
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Rajkumar Verma
- Department of Neurosciences Uconn Health Center, Farmington, CT, United States of America
| | | | - Dean Wright
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Xing-Ding Zhang
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
| | - Constanze Seidenbecher
- Department for Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology Magdeburg, Magdeburg, Germany. .,Center for Behavioral Brain Sciences (CBBS) Magdeburg, Magdeburg, Germany.
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Wahlstrom-Helgren S, Klyachko VA. Dynamic balance of excitation and inhibition rapidly modulates spike probability and precision in feed-forward hippocampal circuits. J Neurophysiol 2016; 116:2564-2575. [PMID: 27605532 DOI: 10.1152/jn.00413.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 09/07/2016] [Indexed: 12/11/2022] Open
Abstract
Feed-forward inhibitory (FFI) circuits are important for many information-processing functions. FFI circuit operations critically depend on the balance and timing between the excitatory and inhibitory components, which undergo rapid dynamic changes during neural activity due to short-term plasticity (STP) of both components. How dynamic changes in excitation/inhibition (E/I) balance during spike trains influence FFI circuit operations remains poorly understood. In the current study we examined the role of STP in the FFI circuit functions in the mouse hippocampus. Using a coincidence detection paradigm with simultaneous activation of two Schaffer collateral inputs, we found that the spiking probability in the target CA1 neuron was increased while spike precision concomitantly decreased during high-frequency bursts compared with a single spike. Blocking inhibitory synaptic transmission revealed that dynamics of inhibition predominately modulates the spike precision but not the changes in spiking probability, whereas the latter is modulated by the dynamics of excitation. Further analyses combining whole cell recordings and simulations of the FFI circuit suggested that dynamics of the inhibitory circuit component may influence spiking behavior during bursts by broadening the width of excitatory postsynaptic responses and that the strength of this modulation depends on the basal E/I ratio. We verified these predictions using a mouse model of fragile X syndrome, which has an elevated E/I ratio, and found a strongly reduced modulation of postsynaptic response width during bursts. Our results suggest that changes in the dynamics of excitatory and inhibitory circuit components due to STP play important yet distinct roles in modulating the properties of FFI circuits.
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Affiliation(s)
- Sarah Wahlstrom-Helgren
- Departments of Cell Biology & Physiology and Biomedical Engineering, Center for the Investigation of Membrane Excitable Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - Vitaly A Klyachko
- Departments of Cell Biology & Physiology and Biomedical Engineering, Center for the Investigation of Membrane Excitable Diseases, Washington University School of Medicine, St. Louis, Missouri
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14
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Involvement of Potassium and Cation Channels in Hippocampal Abnormalities of Embryonic Ts65Dn and Tc1 Trisomic Mice. EBioMedicine 2015; 2:1048-62. [PMID: 26501103 PMCID: PMC4588457 DOI: 10.1016/j.ebiom.2015.07.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 01/09/2023] Open
Abstract
Down syndrome (DS) mouse models exhibit cognitive deficits, and are used for studying the neuronal basis of DS pathology. To understand the differences in the physiology of DS model neurons, we used dissociated neuronal cultures from the hippocampi of Ts65Dn and Tc1 DS mice. Imaging of [Ca2+]i and whole cell patch clamp recordings were used to analyze network activity and single neuron properties, respectively. We found a decrease of ~ 30% in both fast (A-type) and slow (delayed rectifier) outward potassium currents. Depolarization of Ts65Dn and Tc1 cells produced fewer spikes than diploid cells. Their network bursts were smaller and slower than diploids, displaying a 40% reduction in Δf / f0 of the calcium signals, and a 30% reduction in propagation velocity. Additionally, Ts65Dn and Tc1 neurons exhibited changes in the action potential shape compared to diploid neurons, with an increase in the amplitude of the action potential, a lower threshold for spiking, and a sharp decrease of about 65% in the after-hyperpolarization amplitude. Numerical simulations reproduced the DS measured phenotype by variations in the conductance of the delayed rectifier and A-type, but necessitated also changes in inward rectifying and M-type potassium channels and in the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. We therefore conducted whole cell patch clamp measurements of M-type potassium currents, which showed a ~ 90% decrease in Ts65Dn neurons, while HCN measurements displayed an increase of ~ 65% in Ts65Dn cells. Quantitative real-time PCR analysis indicates overexpression of 40% of KCNJ15, an inward rectifying potassium channel, contributing to the increased inhibition. We thus find that changes in several types of potassium channels dominate the observed DS model phenotype. Down syndrome model neurons display altered action potential shape, are less excitable and have decreased potassium currents. The data is accurately described by a numerical simulation that changes conductance of four potassium and the HCN currents. Measurements of the currents related to these four channels, and RT-pcr for a fifth (KCNJ15), confirm the numerical model.
In Down syndrome (DS) cognitive function is impaired, leading us to use cultured hippocampal neuronal networks to investigate the cellular basis of its pathology. DS mouse model neurons are less excitable, produce fewer spikes and generate less network activity. Alterations in several types of potassium currents were detected in these neurons. Numerical simulation of a DS neuron successfully reproduced the experimental results. Beyond extending our understanding of neuronal function and pathology, the alterations in channel conductance can now be targeted with specific drugs so as to point to new directions in therapy of cognitive disabilities of DS.
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Key Words
- 1D, one-dimensional
- 2D, two-dimensional
- DC, direct current
- DS, Down syndrome
- Down syndrome
- EPSC, excitatory post synaptic current
- GABA, gamma-aminobutyric acid
- GIRK, G protein-coupled inwardly-rectifying potassium channels
- HCN, hyperpolarization-activated cyclic nucleotide-gated
- Hippocampus
- Inward rectifiers
- Potassium channels
- Potassium currents
- ROI, region of interest
- RT-PCR, real time polymerase chain reaction
- Reduced excitability
- SEM, standard error of mean
- TTX, tetrodotoxin
- Tc1
- Ts65Dn
- WT, wild type
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15
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Kable JA, Reynolds JN, Valenzuela CF, Medina AE. Proceedings of the 2013 annual meeting of the Fetal Alcohol Spectrum Disorders Study Group. Alcohol 2014; 48:623-30. [PMID: 25224492 PMCID: PMC4250505 DOI: 10.1016/j.alcohol.2014.08.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The 2013 Fetal Alcohol Spectrum Disorders Study Group (FASDSG) meeting was held in Orlando (Grand Cypress), FL with the theme "Developing Brain-Based Interventions for Individuals with Fetal Alcohol Spectrum Disorders." Children with fetal alcohol spectrum disorders have significant impairments in cognitive functioning and behavioral regulation skills, which lead to a lifetime of challenges for themselves and their families; thus, developing interventions that remediate or compensate for these deficits is of great importance. The conference included 2 keynote presentations, FASt data talks, award presentations, and updates by government agencies. In addition, a lively panel discussion addressed the challenges faced by FASDSG researchers in the translation of intervention strategies developed in preclinical studies to clinical trials and, ultimately, to clinical practice.
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Affiliation(s)
- Julie A Kable
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA.
| | - James N Reynolds
- Department of Biomedical and Molecular Sciences, Queens University, Kingston, Ontario, Canada
| | - C Fernando Valenzuela
- University Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Alexandre E Medina
- Department of Pediatrics, University of Maryland, School of Medicine, Baltimore, MD, USA
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16
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Karasawa T, Lombroso PJ. Disruption of striatal-enriched protein tyrosine phosphatase (STEP) function in neuropsychiatric disorders. Neurosci Res 2014; 89:1-9. [PMID: 25218562 DOI: 10.1016/j.neures.2014.08.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 08/12/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) is a brain-specific tyrosine phosphatase that plays a major role in the development of synaptic plasticity. Recent findings have implicated STEP in several psychiatric and neurological disorders, including Alzheimer's disease, schizophrenia, fragile X syndrome, Huntington's disease, stroke/ischemia, and stress-related psychiatric disorders. In these disorders, STEP protein expression levels and activity are dysregulated, contributing to the cognitive deficits that are present. In this review, we focus on the most recent findings on STEP, discuss how STEP expression and activity are maintained during normal cognitive function, and how disruptions in STEP activity contribute to a number of illnesses.
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Affiliation(s)
- Takatoshi Karasawa
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi 480-0392, Japan.
| | - Paul J Lombroso
- Departments of Neurobiology, Psychiatry and Child Study Center, Yale University School of Medicine, New Haven, CT 06520, USA
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17
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mTOR Hyperactivation in Down Syndrome Hippocampus Appears Early During Development. J Neuropathol Exp Neurol 2014; 73:671-83. [DOI: 10.1097/nen.0000000000000083] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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18
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Thomazeau A, Lassalle O, Iafrati J, Souchet B, Guedj F, Janel N, Chavis P, Delabar J, Manzoni OJ. Prefrontal deficits in a murine model overexpressing the down syndrome candidate gene dyrk1a. J Neurosci 2014; 34:1138-47. [PMID: 24453307 PMCID: PMC3953590 DOI: 10.1523/jneurosci.2852-13.2014] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 11/29/2013] [Accepted: 12/06/2013] [Indexed: 12/16/2022] Open
Abstract
The gene Dyrk1a is the mammalian ortholog of Drosophila minibrain. Dyrk1a localizes in the Down syndrome (DS) critical region of chromosome 21q22.2 and is a major candidate for the behavioral and neuronal abnormalities associated with DS. PFC malfunctions are a common denominator in several neuropsychiatric diseases, including DS, but the contribution of DYRK1A in PFC dysfunctions, in particular the synaptic basis for impairments of executive functions reported in DS patients, remains obscure. We quantified synaptic plasticity, biochemical synaptic markers, and dendritic morphology of deep layer pyramidal PFC neurons in adult mBACtgDyrk1a transgenic mice that overexpress Dyrk1a under the control of its own regulatory sequences. We found that overexpression of Dyrk1a largely increased the number of spines on oblique dendrites of pyramidal neurons, as evidenced by augmented spine density, higher PSD95 protein levels, and larger miniature EPSCs. The dendritic alterations were associated with anomalous NMDAR-mediated long-term potentiation and accompanied by a marked reduction in the pCaMKII/CaMKII ratio in mBACtgDyrk1a mice. Retrograde endocannabinoid-mediated long-term depression (eCB-LTD) was ablated in mBACtgDyrk1a mice. Administration of green tea extracts containing epigallocatechin 3-gallate, a potent DYRK1A inhibitor, to adult mBACtgDyrk1a mice normalized long-term potentiation and spine anomalies but not eCB-LTD. However, inhibition of the eCB deactivating enzyme monoacylglycerol lipase normalized eCB-LTD in mBACtgDyrk1a mice. These data shed light on previously undisclosed participation of DYRK1A in adult PFC dendritic structures and synaptic plasticity. Furthermore, they suggest its involvement in DS-related endophenotypes and identify new potential therapeutic strategies.
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Affiliation(s)
- Aurore Thomazeau
- Institut National de la Santé et de la Recherche Médicale U901, Marseille, 13009, France, Université Aix-Marseille UMR S901, Marseille, 13009, France, INMED, Marseille, 13009, France, and Université Paris Diderot, Sorbonne Paris Cité, Adaptive Functional Biology, EAC Centre National de la Recherche Scientifique 4413, Paris, 75205, France
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19
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Jovanov Milošević N, Judaš M, Aronica E, Kostovic I. Neural ECM in laminar organization and connectivity development in healthy and diseased human brain. PROGRESS IN BRAIN RESEARCH 2014; 214:159-78. [DOI: 10.1016/b978-0-444-63486-3.00007-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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20
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Zhan PY, Peng CX, Zhang LH. Berberine rescues D-galactose-induced synaptic/memory impairment by regulating the levels of Arc. Pharmacol Biochem Behav 2013; 117:47-51. [PMID: 24342459 DOI: 10.1016/j.pbb.2013.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/29/2013] [Accepted: 12/05/2013] [Indexed: 12/31/2022]
Abstract
Synaptic communication forms the basis of learning and memory. Disruptions of synaptic function and memory have been widely reported in many neurological diseases, such as dementia. Thus, restoration of impaired synaptic communication is a potential therapeutic approach for these diseases. In this study, we demonstrated that supplementation with berberine, a plant alkaloid with a long history of medicinal usage in Chinese medicine, effectively reverses the synaptic deficits induced by D-galactose. We also found that berberine rescued D-galactose-induced memory impairment and additionally rescued the mRNA and protein levels of Arc/Arg3.1, an important immediate early gene that is crucial for maintaining normal synaptic plasticity. Our study provides the first piece of evidence supporting the potential use of berberine in the treatment of neural diseases with synaptic/memory impairments.
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Affiliation(s)
- Pei-Yan Zhan
- Department of Neurology, Central Hospital of Wuhan, Wuhan 430014, China.
| | - Cai-Xia Peng
- Department of Neurology, Central Hospital of Wuhan, Wuhan 430014, China
| | - Lin-Hong Zhang
- Department of Neurology, Central Hospital of Wuhan, Wuhan 430014, China.
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21
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Baguley TD, Xu HC, Chatterjee M, Nairn AC, Lombroso PJ, Ellman JA. Substrate-based fragment identification for the development of selective, nonpeptidic inhibitors of striatal-enriched protein tyrosine phosphatase. J Med Chem 2013; 56:7636-50. [PMID: 24083656 DOI: 10.1021/jm401037h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High levels of striatal-enriched protein tyrosine phosphatase (STEP) activity are observed in a number of neuropsychiatric disorders such as Alzheimer's disease. Overexpression of STEP results in the dephosphorylation and inactivation of many key neuronal signaling molecules, including ionotropic glutamate receptors. Moreover, genetically reducing STEP levels in AD mouse models significantly reversed cognitive deficits and decreased glutamate receptor internalization. These results support STEP as a potential target for drug discovery for the treatment of Alzheimer's disease. Herein, a substrate-based approach for the discovery and optimization of fragments called substrate activity screening (SAS) has been applied to the development of low molecular weight (<450 Da) and nonpeptidic, single-digit micromolar mechanism-based STEP inhibitors with greater than 20-fold selectivity across multiple tyrosine and dual specificity phosphatases. Significant levels of STEP inhibition in rat cortical neurons are also observed.
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Affiliation(s)
- Tyler D Baguley
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States
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22
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Van Maldergem L, Hou Q, Kalscheuer VM, Rio M, Doco-Fenzy M, Medeira A, de Brouwer APM, Cabrol C, Haas SA, Cacciagli P, Moutton S, Landais E, Motte J, Colleaux L, Bonnet C, Villard L, Dupont J, Man HY. Loss of function of KIAA2022 causes mild to severe intellectual disability with an autism spectrum disorder and impairs neurite outgrowth. Hum Mol Genet 2013; 22:3306-14. [PMID: 23615299 DOI: 10.1093/hmg/ddt187] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Existence of a discrete new X-linked intellectual disability (XLID) syndrome due to KIAA2022 deficiency was questioned by disruption of KIAA2022 by an X-chromosome pericentric inversion in a XLID family we reported in 2004. Three additional families with likely pathogenic KIAA2022 mutations were discovered within the frame of systematic parallel sequencing of familial cases of XLID or in the context of routine array-CGH evaluation of sporadic intellectual deficiency (ID) cases. The c.186delC and c.3597dupA KIAA2022 truncating mutations were identified by X-chromosome exome sequencing, while array CGH discovered a 70 kb microduplication encompassing KIAA2022 exon 1 in the third family. This duplication decreased KIAA2022 mRNA level in patients' lymphocytes by 60%. Detailed clinical examination of all patients, including the two initially reported, indicated moderate-to-severe ID with autistic features, strabismus in all patients, with no specific dysmorphic features other than a round face in infancy and no structural brain abnormalities on magnetic resonance imaging (MRI). Interestingly, the patient with decreased KIAA2022 expression had only mild ID with severe language delay and repetitive behaviors falling in the range of an autism spectrum disorder (ASD). Since little is known about KIAA2022 function, we conducted morphometric studies in cultured rat hippocampal neurons. We found that siRNA-mediated KIAA2022 knockdown resulted in marked impairment in neurite outgrowth including both the dendrites and the axons, suggesting a major role for KIAA2022 in neuron development and brain function.
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Affiliation(s)
- Lionel Van Maldergem
- Centre de Génétique Humaine, Université de Franche-Comté, 25000 Besançon, France.
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23
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Wei S, Soh SLY, Qiu W, Yang W, Seah CJY, Guo J, Ong WY, Pang ZP, Han W. Seipin regulates excitatory synaptic transmission in cortical neurons. J Neurochem 2012; 124:478-89. [PMID: 23173741 DOI: 10.1111/jnc.12099] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 11/20/2012] [Accepted: 11/20/2012] [Indexed: 12/20/2022]
Abstract
Heterozygosity for missense mutations in Seipin, namely N88S and S90L, leads to a broad spectrum of motor neuropathy, while a number of loss-of-function mutations in Seipin are associated with the Berardinelli-Seip congenital generalized lipodystrophy type 2 (CGL2, BSCL2), a condition that is characterized by severe lipoatrophy, insulin resistance, and intellectual impairment. The mechanisms by which Seipin mutations lead to motor neuropathy, lipodystrophy, and insulin resistance, and the role Seipin plays in central nervous system (CNS) remain unknown. The goal of this study is to understand the functions of Seipin in the CNS using a loss-of-function approach, i.e. by knockdown (KD) of Seipin gene expression. Excitatory post-synaptic currents (EPSCs) were impaired in Seipin-KD neurons, while the inhibitory post-synaptic currents (IPSCs) remained unaffected. Expression of a shRNA-resistant human Seipin rescued the impairment of EPSC produced by Seipin KD. Furthermore, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced whole-cell currents were significantly reduced in Seipin KD neurons, which could be rescued by expression of a shRNA-resistant human Seipin. Fluorescent imaging and biochemical studies revealed reduced level of surface AMPA receptors, while no obvious ultrastructural changes in the pre-synapse were found. These data suggest that Seipin regulates excitatory synaptic function through a post-synaptic mechanism.
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Affiliation(s)
- Shunhui Wei
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore
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