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Wang H, Chang L, Aguilar JS, Dong S, Hong Y. Bisphenol-A exposure induced neurotoxicity in glutamatergic neurons derived from human embryonic stem cells. ENVIRONMENT INTERNATIONAL 2019; 127:324-332. [PMID: 30953815 DOI: 10.1016/j.envint.2019.01.059] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/22/2019] [Accepted: 01/22/2019] [Indexed: 06/09/2023]
Abstract
Bisphenol-A (BPA) is a lipophilic, organic, synthetic compound that has been used as an additive in polycarbonate plastics manufacturing since 1957. Studies have shown that BPA interferes with the development and functions of the brain, but little is known about the effects of BPA on human glutamatergic neurons (hGNs) at the molecular and cellular levels. We investigated the impact of chronic exposure to BPA to hGNs derived from human embryonic stem cells (hESCs). The results showed that chronic exposure of different concentrations of BPA (0, 0.1, 1.0 and 10 μM) to hGNs for 14 days reduced neurite outgrowth in a concentration-dependent manner. Using presynaptic protein synaptophysin and postsynaptic protein PSD-95 antibodies, immunofluorescence staining and western blotting results indicated that BPA exposure altered the morphology of dendritic spines and increased synaptophysin and PSD-95 expression. Furthermore, BPA exposure at concentrations higher than 1.0 μM resulted in the increase of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) expression and deterioration of dendritic spines. In addition, our results suggested that these BPA mediated neurotoxicity effects were due to an increased production of reactive nitrogen species (RNS) and reactive oxygen species (ROS) via increased nitric oxide synthase (iNOS), neuronal nitric oxide synthase (nNOS), 3-nitrotyrosine expression and Ca2+ influx. These results imply that hESC-based neuronal differentiation is an excellent cellular model to examine BPA-induced neurotoxicity on human neurons at the cellular and molecular level.
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Affiliation(s)
- Hongou Wang
- College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA 91766-1854, USA; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lawrence Chang
- College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA 91766-1854, USA; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766-1854, USA
| | - Jose S Aguilar
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766-1854, USA
| | - Sijun Dong
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
| | - Yiling Hong
- College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA 91766-1854, USA; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766-1854, USA.
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Kiese K, Jablonski J, Hackenbracht J, Wrosch JK, Groemer TW, Kornhuber J, Blümcke I, Kobow K. Epigenetic control of epilepsy target genes contributes to a cellular memory of epileptogenesis in cultured rat hippocampal neurons. Acta Neuropathol Commun 2017; 5:79. [PMID: 29089052 PMCID: PMC5664434 DOI: 10.1186/s40478-017-0485-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/25/2017] [Indexed: 02/01/2023] Open
Abstract
Hypersynchronous neuronal excitation manifests clinically as seizure (ictogenesis), and may recur spontaneously and repetitively after a variable latency period (epileptogenesis). Despite tremendous research efforts to describe molecular pathways and signatures of epileptogenesis, molecular pathomechanisms leading to chronic epilepsy remain to be clarified. We hypothesized that epigenetic modifications may form the basis for a cellular memory of epileptogenesis, and used a primary neuronal cell culture model of the rat hippocampus to study the translation of massive neuronal excitation into persisting changes of epigenetic signatures and pro-epileptogenic target gene expression. Increased spontaneous activation of cultured neurons was detected 3 and 7 days after stimulation with 10 μM glutamate when compared to sham-treated time-matched controls using calcium-imaging in vitro. Chromatin-immunoprecipitation experiments revealed short-term (3 h, 7 h, and 24 h) and long-term (3 d and 2 weeks) changes in histone modifications, which were directly linked to decreased expression of two selected epilepsy target genes, e.g. excitatory glutamate receptor genes Gria2 and Grin2a. Increased promoter methylation observed 4 weeks after glutamate stimulation at respective genes suggested long-term repression of Gria2 and Grin2a genes. Inhibition of glutamatergic activation or blocking the propagation of action potentials in cultured neurons rescued altered gene expression and regulatory epigenetic modifications. Our data support the concept of a cellular memory of epileptogenesis and persisting epigenetic modifications of epilepsy target genes, which are able to turn normal into pro-epileptic neurons and circuits.
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Evans AJ, Gurung S, Wilkinson KA, Stephens DJ, Henley JM. Assembly, Secretory Pathway Trafficking, and Surface Delivery of Kainate Receptors Is Regulated by Neuronal Activity. Cell Rep 2017; 19:2613-2626. [PMID: 28636947 PMCID: PMC5489663 DOI: 10.1016/j.celrep.2017.06.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 04/17/2017] [Accepted: 05/25/2017] [Indexed: 01/03/2023] Open
Abstract
Ionotropic glutamate receptor (iGluR) trafficking and function underpin excitatory synaptic transmission and plasticity and shape neuronal networks. It is well established that the transcription, translation, and endocytosis/recycling of iGluRs are all regulated by neuronal activity, but much less is known about the activity dependence of iGluR transport through the secretory pathway. Here, we use the kainate receptor subunit GluK2 as a model iGluR cargo to show that the assembly, early secretory pathway trafficking, and surface delivery of iGluRs are all controlled by neuronal activity. We show that the delivery of de novo kainate receptors is differentially regulated by modulation of GluK2 Q/R editing, PKC phosphorylation, and PDZ ligand interactions. These findings reveal that, in addition to short-term regulation of iGluRs by recycling/endocytosis and long-term modulation by altered transcription/translation, the trafficking of iGluRs through the secretory pathway is under tight activity-dependent control to determine the numbers and properties of surface-expressed iGluRs.
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Affiliation(s)
- Ashley J Evans
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Sonam Gurung
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Kevin A Wilkinson
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - David J Stephens
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Jeremy M Henley
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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Clossen BL, Reddy DS. Novel therapeutic approaches for disease-modification of epileptogenesis for curing epilepsy. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1519-1538. [PMID: 28179120 PMCID: PMC5474195 DOI: 10.1016/j.bbadis.2017.02.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/31/2017] [Accepted: 02/03/2017] [Indexed: 11/16/2022]
Abstract
This article describes the recent advances in epileptogenesis and novel therapeutic approaches for the prevention of epilepsy, with a special emphasis on the pharmacological basis of disease-modification of epileptogenesis for curing epilepsy. Here we assess animal studies and human clinical trials of epilepsy spanning 1982-2016. Epilepsy arises from a number of neuronal factors that trigger epileptogenesis, which is the process by which a brain shifts from a normal physiologic state to an epileptic condition. The events precipitating these changes can be of diverse origin, including traumatic brain injury, cerebrovascular damage, infections, chemical neurotoxicity, and emergency seizure conditions such as status epilepticus. Expectedly, the molecular and system mechanisms responsible for epileptogenesis are not well defined or understood. To date, there is no approved therapy for the prevention of epilepsy. Epigenetic dysregulation, neuroinflammation, and neurodegeneration appear to trigger epileptogenesis. Targeted drugs are being identified that can truly prevent the development of epilepsy in at-risk people. The promising agents include rapamycin, COX-2 inhibitors, TRK inhibitors, epigenetic modulators, JAK-STAT inhibitors, and neurosteroids. Recent evidence suggests that neurosteroids may play a role in modulating epileptogenesis. A number of promising drugs are under investigation for the prevention or modification of epileptogenesis to halt the development of epilepsy. Some drugs in development appear rational for preventing epilepsy because they target the initial trigger or related signaling pathways as the brain becomes progressively more prone to seizures. Additional research into the target validity and clinical investigation is essential to make new frontiers in curing epilepsy.
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Affiliation(s)
- Bryan L Clossen
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA.
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Szczurowska E, Ergang P, Kubová H, Druga R, Salaj M, Mareš P. Influence of early life status epilepticus on the developmental expression profile of the GluA2 subunit of AMPA receptors. Exp Neurol 2016; 283:97-109. [DOI: 10.1016/j.expneurol.2016.05.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 05/13/2016] [Accepted: 05/29/2016] [Indexed: 01/12/2023]
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Dixit AB, Tripathi M, Chandra PS, Banerjee J. Molecular biomarkers in drug-resistant epilepsy: Facts & possibilities. Int J Surg 2015; 36:483-491. [PMID: 26306771 DOI: 10.1016/j.ijsu.2015.08.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/03/2015] [Indexed: 01/08/2023]
Abstract
Despite great advances in our understanding of the process of epileptogenesis we are yet to develop reliable biomarkers that have the potential to accurately localize the epileptogenic zone (EZ), and to resolve the issue of heterogeneity in epilepsy surgery outcome. Inability to precisely localize the epileptogenic foci is one of the reason why more than 30% of these DRE patients are not benefited. Molecular and cellular biomarkers in combination with imaging and electrical investigations will provide a more specific platform for defining epileptogenic zone. Potential molecular biomarkers of epileptogenesis including markers of inflammation, synaptic alterations and neurodegeneration may also have the potential for localizing EZ. At molecular level components derived from epileptogenic tissues, such as metabolites, proteins, mRNAs and miRNAs that are significantly altered can serve as biomarkers and can be clubbed with existing techniques to preoperatively localize the EZ. Neurosurgeons across the world face problems while defining the margins of the epileptogenic tissues to be resected during surgery. In this review we discuss molecular biomarkers reported so far in the context of epileptogenesis and some of the unexplored markers which may have the potential to localize EZ during surgery. We also discuss "Intelligent knife" technique that couples electrosurgery and mass spectrometry allowing near-real-time characterization of human tissue and may prove to be instrumental in defining the margins of the epileptogenic zone during surgery.
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Affiliation(s)
- Aparna Banerjee Dixit
- Center of Excellence for Epilepsy, National Brain Research Centre, Manesar, 122051, India
| | - Manjari Tripathi
- Dept. of Neurology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - P Sarat Chandra
- Dept. of Neurosurgery, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Jyotirmoy Banerjee
- Center of Excellence for Epilepsy, National Brain Research Centre, Manesar, 122051, India.
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The Transcription Repressor REST in Adult Neurons: Physiology, Pathology, and Diseases. eNeuro 2015; 2:eN-REV-0010-15. [PMID: 26465007 PMCID: PMC4596026 DOI: 10.1523/eneuro.0010-15.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 06/11/2015] [Accepted: 06/18/2015] [Indexed: 12/21/2022] Open
Abstract
REST [RE1-silencing transcription factor (also called neuron-restrictive silencer factor)] is known to repress thousands of possible target genes, many of which are neuron specific. To date, REST repression has been investigated mostly in stem cells and differentiating neurons. Current evidence demonstrates its importance in adult neurons as well. Low levels of REST, which are acquired during differentiation, govern the expression of specific neuronal phenotypes. REST-dependent genes encode important targets, including transcription factors, transmitter release proteins, voltage-dependent and receptor channels, and signaling proteins. Additional neuronal properties depend on miRNAs expressed reciprocally to REST and on specific splicing factors. In adult neurons, REST levels are not always low. Increases occur during aging in healthy humans. Moreover, extensive evidence demonstrates that prolonged stimulation with various agents induces REST increases, which are associated with the repression of neuron-specific genes with appropriate, intermediate REST binding affinity. Whether neuronal increases in REST are protective or detrimental remains a subject of debate. Examples of CA1 hippocampal neuron protection upon depolarization, and of neurodegeneration upon glutamate treatment and hypoxia have been reported. REST participation in psychiatric and neurological diseases has been shown, especially in Alzheimer’s disease and Huntington’s disease, as well as epilepsy. Distinct, complex roles of the repressor in these different diseases have emerged. In conclusion, REST is certainly very important in a large number of conditions. We suggest that the conflicting results reported for the role of REST in physiology, pathology, and disease depend on its complex, direct, and indirect actions on many gene targets and on the diverse approaches used during the investigations.
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Repeated application of 4-aminopyridine provoke an increase in entorhinal cortex excitability and rearrange AMPA and kainate receptors. Neurotox Res 2015; 27:441-52. [PMID: 25576253 DOI: 10.1007/s12640-014-9515-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 12/29/2014] [Accepted: 12/30/2014] [Indexed: 02/03/2023]
Abstract
Entorhinal cortex is a highly epilepsy-prone brain region. Effects of repetitive seizures on ionotropic glutamate receptors (iGluRs) were investigated in rat entorhinal cortex slices. Seizures were induced by daily administration of 4-aminopyridine (4-AP). Electrophysiological, pharmacological and histological investigations were carried out to determine changes in synaptic efficacy and in sensitivity of iGluRs due to recurring seizures. Repeated 4-AP-induced seizures increased the amplitude of evoked synaptic field responses in rat entorhinal cortical slices. While vulnerability to inhibition of AMPA receptors by the specific antagonist GYKI 52466 was slightly reduced, responsiveness to NMDA receptor antagonist APV remained unaffected. Testing of bivalent cation permeability of iGluRs revealed reduced Ca(2+)-influx through non-NMDA receptors. According to the semi-quantitative histoblot analysis GluA1-4, GluA1, GluA2, GluK5, GluN1 and GluN2A subunit protein expression differently altered. While there was a marked decrease in the level of GluA1-4, GluA2 and GluK5 receptor subunits, GluA1 and GluN2A protein levels moderately increased. The results indicate that brief convulsions, repeated daily for 10 days can increase overall entorhinal cortex excitability despite a reduction in AMPA/kainate receptor activity, probably through the alteration of local network susceptibility.
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Abstract
In humans, genomic DNA is organized in 23 chromosome pairs coding for roughly 25,000 genes. Not all of them are active at all times. During development, a broad range of different cell types needs to be generated in a highly ordered and reproducible manner, requiring selective gene expression programs. Epigenetics can be regarded as the information management system that is able to index or bookmark distinct regions in our genome to regulate the readout of DNA. It further comprises the molecular memory of any given cell, allowing it to store information of previously experienced external (e.g., environmental) or internal (e.g., developmental) stimuli, to learn from this experience and to respond. The underlying epigenetic mechanisms can be synergistic, antagonistic, or mutually exclusive and their large variety combined with the variability and interdependence is thought to provide the molecular basis for any phenotypic variation in physiological and pathological conditions. Thus, widespread reconfiguration of the epigenome is not only a key feature of neurodevelopment, brain maturation, and adult brain function but also disease.
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Affiliation(s)
- Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage, Erlangen, Germany
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage, Erlangen, Germany.
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Kobow K, Kaspi A, Harikrishnan KN, Kiese K, Ziemann M, Khurana I, Fritzsche I, Hauke J, Hahnen E, Coras R, Mühlebner A, El-Osta A, Blümcke I. Deep sequencing reveals increased DNA methylation in chronic rat epilepsy. Acta Neuropathol 2013; 126:741-56. [PMID: 24005891 PMCID: PMC3825532 DOI: 10.1007/s00401-013-1168-8] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 08/15/2013] [Indexed: 12/12/2022]
Abstract
Epilepsy is a frequent neurological disorder, although onset and progression of seizures remain difficult to predict in affected patients, irrespective of their epileptogenic condition. Previous studies in animal models as well as human epileptic brain tissue revealed a remarkably diverse pattern of gene expression implicating epigenetic changes to contribute to disease progression. Here we mapped for the first time global DNA methylation patterns in chronic epileptic rats and controls. Using methyl-CpG capture associated with massive parallel sequencing (Methyl-Seq) we report the genomic methylation signature of the chronic epileptic state. We observed a predominant increase, rather than loss of DNA methylation in chronic rat epilepsy. Aberrant methylation patterns were inversely correlated with gene expression changes using mRNA sequencing from same animals and tissue specimens. Administration of a ketogenic, high-fat, low-carbohydrate diet attenuated seizure progression and ameliorated DNA methylation mediated changes in gene expression. This is the first report of unsupervised clustering of an epigenetic mark being used in epilepsy research to separate epileptic from non-epileptic animals as well as from animals receiving anti-convulsive dietary treatment. We further discuss the potential impact of epigenetic changes as a pathogenic mechanism of epileptogenesis.
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Affiliation(s)
- Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Antony Kaspi
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, VIC Australia
| | - K. N. Harikrishnan
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, VIC Australia
| | - Katharina Kiese
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Mark Ziemann
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, VIC Australia
| | - Ishant Khurana
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, VIC Australia
| | - Ina Fritzsche
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Jan Hauke
- Center of Familial Breast and Ovarian Cancer, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Eric Hahnen
- Center of Familial Breast and Ovarian Cancer, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Roland Coras
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Angelika Mühlebner
- Department of Pediatrics and Adolescent Medicine, Medical University Vienna, Vienna, Austria
| | - Assam El-Osta
- Epigenetics in Human Health and Disease, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, VIC Australia
- Epigenomics Profiling Facility, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, VIC Australia
- Department of Pathology, The University of Melbourne, Parkville, VIC Australia
- Faculty of Medicine, Monash University, Melbourne, VIC Australia
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen, Germany
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Kobow K, El-Osta A, Blümcke I. The methylation hypothesis of pharmacoresistance in epilepsy. Epilepsia 2013; 54 Suppl 2:41-7. [PMID: 23646970 DOI: 10.1111/epi.12183] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Seizures cannot be medically controlled in approximately 40% of people with epilepsy. Although we are beginning to understand how to better treat certain seizure types, we still do not know the regulatory events that determine antiepileptic drug resistance. Proposed pathoetiologic mechanisms include altered expression of drug targets (i.e., receptor or ion channel modifications), endothelial drug transporter activation (i.e., increasing drug clearance), or intrinsic severity factors. The latter hypothesis results from an often confirmed clinical observation, that seizure severity is a reliable predictor for the development of pharmacoresistance (PR) in epilepsy. Herein, we propose, that genome modifications that do not involve changes to the DNA sequence per se (i.e., epigenetic changes) could confer PR in patients with epilepsy. Seizures cause excessive neuronal membrane depolarization, which can influence the cellular nucleus; we thus hypothesize that seizures can mediate epigenetic modifications that result in persistent genomic methylation, histone density, and posttranslational modifications, as well as noncoding RNA-based changes. Although experimental evidence is lacking in epilepsy, such mechanisms are well characterized in cancer, either as a result of anticancer drugs themselves or cancer-related intrinsic signals (i.e., noncoding RNAs). We suggest that similar mechanisms also play a role in PR epilepsies. Addressing such epigenetic mechanisms may be a successful strategy to increase the brain's sensitivity to antiepileptic drugs and may even act as disease-modifying treatment.
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Affiliation(s)
- Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
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Kobow K, Blümcke I. The emerging role of DNA methylation in epileptogenesis. Epilepsia 2013; 53 Suppl 9:11-20. [PMID: 23216575 DOI: 10.1111/epi.12031] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
DNA methylation is a covalent chromatin modification, characterized by the biochemical addition of a methyl group (-CH3) to cytosine nucleotides via a DNA methyltransferase enzyme. 5'-Methylcytosine (5-mC), frequently called the fifth base, has been implicated in genome stability, silencing of transposable elements, and repression of gene expression. Through the latter, DNA methylation dynamics broadly influence brain development, function, and aging. Aberrant DNA methylation patterns, either localized to specific gene regions or scattered throughout the genome, are associated with many neurologic disorders. Herein, we discuss the emerging role of DNA methylation in epileptogenesis and the perspectives arising from epigenetic medicine as new therapeutic strategy in difficult-to-treat epilepsies.
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Affiliation(s)
- Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
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Abstract
Epigenetic mechanisms are regulatory processes that control gene expression changes involved in multiple aspects of neuronal function, including central nervous system development, synaptic plasticity, and memory. Recent evidence indicates that dysregulation of epigenetic mechanisms occurs in several human epilepsy syndromes. Despite this discovery of a potential role for epigenetic mechanisms in epilepsy, few studies have fully explored their contribution to the process of epilepsy development known as epileptogenesis. The purpose of this article is to discuss recent findings suggesting that the process of epileptogenesis may alter the epigenetic landscape, affecting the gene expression patterns observed in epilepsy. Future studies focused on a better characterization of these aberrant epigenetic mechanisms hold the promise of revealing novel treatment options for the prevention and even the reversal of epilepsy.
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Regulation of mGluR1 expression in human melanocytes and melanoma cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:1123-31. [PMID: 22771868 DOI: 10.1016/j.bbagrm.2012.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 06/21/2012] [Accepted: 06/27/2012] [Indexed: 11/23/2022]
Abstract
We demonstrated that ectopic expression of metabotropic glutamate receptor 1 (mGluR1/Grm1) in mouse melanocytes was sufficient to induce melanoma development in vivo with 100% penetrance. We also showed that about 60% of human melanoma biopsies and cell lines, but not benign nevi or normal human melanocytes expressed mGluR1, suggesting that GRM1 may be involved in melanomagenesis. mGluR1 is expressed primarily in neurons. In various non-neuronal cells, mGluR1 expression is regulated via binding of Neuron-Restrictive-Silencer-Factor (NRSF) to a Neuron-Restrictive-Silencer-Element (NRSE). Here, we report on the possibility that aberrant mGluR1 expression in melanoma is due to alterations in NRSF and/or NRSE. We show that in human melanocytes, binding of NRSF to NRSE in the GRM1 promoter region is necessary for the suppression of mGluR1 expression. We also show that inhibiting the expression of the transcription factor Sp1 or interference with its ability to bind DNA can result in increased mGluR1 expression perhaps via its function as a negative regulator. In addition, we also provide evidence that demethylation within the promoter region of GRM1 may also be a mechanism for the derepression of mGluR1 expression in melanocytes that progress to cell transformation and tumor formation.
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McClelland S, Flynn C, Dubé C, Richichi C, Zha Q, Ghestem A, Esclapez M, Bernard C, Baram TZ. Neuron-restrictive silencer factor-mediated hyperpolarization-activated cyclic nucleotide gated channelopathy in experimental temporal lobe epilepsy. Ann Neurol 2011; 70:454-64. [PMID: 21905079 DOI: 10.1002/ana.22479] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Enduring, abnormal expression and function of the ion channel hyperpolarization-activated cyclic adenosine monophosphate gated channel type 1 (HCN1) occurs in temporal lobe epilepsy (TLE). We examined the underlying mechanisms, and investigated whether interfering with these mechanisms could modify disease course. METHODS Experimental TLE was provoked by kainic acid-induced status epilepticus (SE). HCN1 channel repression was examined at mRNA, protein, and functional levels. Chromatin immunoprecipitation was employed to identify the transcriptional mechanism of repressed HCN1 expression, and the basis for their endurance. Physical interaction of the repressor, NRSF, was abolished using decoy oligodeoxynucleotides (ODNs). Video/electroencephalographic recordings were performed to assess the onset and initial pattern of spontaneous seizures. RESULTS Levels of NRSF and its physical binding to the Hcn1 gene were augmented after SE, resulting in repression of HCN1 expression and HCN1-mediated currents (I(h) ), and reduced I(h) -dependent resonance in hippocampal CA1 pyramidal cell dendrites. Chromatin changes typical of enduring, epigenetic gene repression were apparent at the Hcn1 gene within a week after SE. Administration of decoy ODNs comprising the NRSF DNA-binding sequence (neuron restrictive silencer element [NRSE]), in vitro and in vivo, reduced NRSF binding to Hcn1, prevented its repression, and restored I(h) function. In vivo, decoy NRSE ODN treatment restored theta rhythm and altered the initial pattern of spontaneous seizures. INTERPRETATION Acquired HCN1 channelopathy derives from NRSF-mediated transcriptional repression that endures via chromatin modification and may provide insight into the mechanisms of a number of channelopathies that coexist with, and may contribute to, the conversion of a normal brain into an epileptic one.
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Affiliation(s)
- Shawn McClelland
- Departments of Anatomy/Neurobiology, Pediatrics, and Neurology, University of California-Irvine, Irvine, CA, USA
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Nontelomeric splice variant of telomere repeat-binding factor 2 maintains neuronal traits by sequestering repressor element 1-silencing transcription factor. Proc Natl Acad Sci U S A 2011; 108:16434-9. [PMID: 21903926 DOI: 10.1073/pnas.1106906108] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Telomere repeat-binding factor 2 (TRF2) is critical for telomere integrity in dividing stem and somatic cells, but its role in postmitotic neurons is unknown. Apart from protecting telomeres, nuclear TRF2 interacts with the master neuronal gene-silencer repressor element 1-silencing transcription factor (REST), and disruption of this interaction induces neuronal differentiation. Here we report a developmental switch from the expression of TRF2 in proliferating neural progenitor cells to expression of a unique short nontelomeric isoform of TRF2 (TRF2-S) as neurons establish a fully differentiated state. Unlike nuclear TRF2, which enhances REST-mediated gene repression, TRF2-S is located in the cytoplasm where it sequesters REST, thereby maintaining the expression of neuronal genes, including those encoding glutamate receptors, cell adhesion, and neurofilament proteins. In neurons, TRF2-S-mediated antagonism of REST nuclear activity is greatly attenuated by either overexpression of TRF2 or administration of the excitatory amino acid kainic acid. Overexpression of TRF2-S rescues kainic acid-induced REST nuclear accumulation and its gene-silencing effects. Thus, TRF2-S acts as part of a unique developmentally regulated molecular switch that plays critical roles in the maintenance and plasticity of neurons.
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17
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Park SY, Kim JB, Han YM. REST is a key regulator in brain-specific homeobox gene expression during neuronal differentiation. J Neurochem 2011; 103:2565-74. [PMID: 17944879 DOI: 10.1111/j.1471-4159.2007.04947.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Brain-specific homeobox (Bsx) is specifically expressed at the early embryonic stages during brain development. Several studies show that Bsx plays important roles in brain development; however, the mechanisms of its transcriptional regulation remain to be established. In this study, we show that binding of repressor element silencing transcription factor (REST) to the neuron restrictive silencer element (NRSE) represses Bsx transcription in non-neuronal P19 cells. The Bsx promoter contains several putative binding sites for transcription factors, including NRSE for REST and the GC box for the transcriptional activator, Sp1. Upon neuronal differentiation of P19 cells with retinoic acid, Bsx gene expression increased, whereas that of the REST gene decreased. Electrophoretic mobility shift analyses demonstrated that recombinant REST proteins bound the NRSE region of the Bsx promoter. In neuronal NS20Y cells, transcriptional activity of the Bsx promoter was decreased upon expression of REST. Moreover, dominant-negative REST derepressed Bsx transcription in P19 cells. Sp1-mediated transcriptional activity of the Bsx promoter was attenuated by treatment with mithramycin A, a GC box-binding drug, but was enhanced upon mutation of NRSE. Co-immunoprecipitation and chromatin immunoprecipitation assays showed that the Bsx promoter appeared to be modulated by direct interactions between REST and Sp1. The CpG sites of NRSE and GC box were completely unmethylated, signifying no interference of DNA methylation. Our results suggest that binding of REST to NRSE suppresses the Sp1-mediated activation of Bsx in non-neuronal cells.
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Affiliation(s)
- So Yun Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
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18
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Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine R. Glutamate receptor ion channels: structure, regulation, and function. Pharmacol Rev 2010; 62:405-96. [PMID: 20716669 PMCID: PMC2964903 DOI: 10.1124/pr.109.002451] [Citation(s) in RCA: 2575] [Impact Index Per Article: 183.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
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Affiliation(s)
- Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
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Tanaka T, Ohashi S, Funakoshi T, Kobayashi S. YB-1 binds to GluR2 mRNA and CaM1 mRNA in the brain and regulates their translational levels in an activity-dependent manner. Cell Mol Neurobiol 2010; 30:1089-100. [PMID: 20614234 DOI: 10.1007/s10571-010-9541-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 06/23/2010] [Indexed: 12/11/2022]
Abstract
The translational regulator YB-1 binds to mRNAs. In the brain, YB-1 is prominently expressed from the prenatal stage until the first week after birth, being associated with polysomes and distributed in neuronal dendrites, but its expression declines to a much lower level thereafter. It is therefore of interest to identify the mRNAs whose translation is controlled by YB-1 in the postnatal growing brain. In this study we found that YB-1 interacted with the mRNAs for glutamate receptor subunit 2 (GluR2) and calmodulin1 (CaM1) in both brain and NG108-15 cells. Overexpression or knockdown of YB-1 altered the levels of these proteins significantly in cultured cells without any change in their mRNA levels. When the cells were treated with neurotransmitters, translation of these proteins was induced within a short time, and a change in the amount of YB-1 on its target mRNAs was observed in the heavy-sedimenting polysome fractions on a sucrose gradient. Depletion of YB-1 expression by siRNA abrogated the translational activation. Furthermore, in the brain of kainic acid-treated mice, the distribution of YB-1 was shifted to much heavier fractions associated with polysomes within 30 min to 1 h after the treatment, and the distribution returned to lighter fractions within the following 2 h. The protein levels of GluR2 and CaM1 were also increased transiently when the distribution of YB-1 on the gradient changed. These results suggest that in the brain of growing mice, YB-1 binds to GluR2 and CaM1 mRNAs and regulates their translation in an activity-dependent manner.
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Affiliation(s)
- Toru Tanaka
- Research Unit of Biochemistry, School of Pharmacy, Nihon University, Funabashi, Chiba, Japan
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20
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Li SY, Sun WG, Jia YH, Wu GS, An GS, Ni JH, Jia HT. Calcium signal-initiated early activation of NF-kappaB in neurons is a neuroprotective event in response to kainic acid-induced excitotoxicity. BIOCHEMISTRY (MOSCOW) 2010; 75:101-9. [PMID: 20331430 DOI: 10.1134/s000629791001013x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We demonstrate that activation of nuclear factor kappaB (NF-kappaB) in neurons is neuroprotective in response to kainic acid (KA)-induced excitotoxicity. Combination of Western blotting, immunocytochemistry, and electrophoresis mobility shift assay showed that KA exposure induced a fast but transient nuclear translocation of the NF-kappaB p65 subunit and increased DNA-binding activity of NF-kappaB in primary cultured cortical neurons. The transient NF-kappaB activity was associated with upregulation of antiapoptotic Bcl-xL and XIAP gene products revealed by real-time PCR. Knockdown of p65 decreased neuronal viability and antiapoptotic gene expression. In addition, we showed that KA-stimulated DNA-binding activity of NF-kappaB was associated with reactive oxygen species and calcium signals, using AMPA/KA receptor antagonist, calcium chelator, and antioxidant. These results suggest that the fast and transient activation of NF-kappaB initiated by calcium signals is one of the important proximal events in response to KA-induced excitotoxicity, which has neuroprotective effect against KA-induced apoptosis.
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Affiliation(s)
- Shu-Yan Li
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Beijing, 100191, PR China.
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21
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Qureshi IA, Mehler MF. Epigenetic mechanisms underlying human epileptic disorders and the process of epileptogenesis. Neurobiol Dis 2010; 39:53-60. [PMID: 20188170 DOI: 10.1016/j.nbd.2010.02.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 02/10/2010] [Accepted: 02/13/2010] [Indexed: 10/19/2022] Open
Abstract
The rapidly emerging science of epigenetics and epigenomic medicine promises to reveal novel insights into the susceptibility to and the onset and progression of epileptic disorders. Epigenetic regulatory mechanisms are now implicated in orchestrating aspects of neural development (e.g., cell fate specification and maturation), homeostasis and stress responses (e.g., immediate early gene transcription), and neural network function (e.g., excitation-inhibition coupling and activity-dependent plasticity). These same neurobiological processes are responsible for determining the heterogeneous features of complex epileptic disease states. Thus, we highlight recent evidence that is beginning to elucidate the specific roles played by epigenetic mechanisms, including DNA methylation, histone code modifications and chromatin remodeling, noncoding RNAs and RNA editing, in human epilepsy syndromes and in the process of epileptogenesis. The highly integrated layers of the epigenome are responsible for the cell type specific and exquisitely environmentally responsive deployment of genes and functional gene networks that underlie the molecular pathophysiology of epilepsy and its associated comorbidities, including but not limited to neurotransmitter receptors (e.g., GluR2, GLRA2, and GLRA3), growth factors (e.g., BDNF), extracellular matrix proteins (e.g., RELN), and diverse transcriptional regulators (e.g., CREB, c-fos, and c-jun). These important observations suggest that future epigenetic studies are necessary to better understand, classify, prevent, and treat epileptic disorders.
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Affiliation(s)
- Irfan A Qureshi
- Rosyln and Leslie Goldstein Laboratory for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA.
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22
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Ariano P, Zamburlin P, D'Alessandro R, Meldolesi J, Lovisolo D. Differential repression by the transcription factor REST/NRSF of the various Ca2+ signalling mechanisms in pheochromocytoma PC12 cells. Cell Calcium 2010; 47:360-8. [PMID: 20171735 DOI: 10.1016/j.ceca.2010.01.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 01/21/2010] [Accepted: 01/26/2010] [Indexed: 01/20/2023]
Abstract
Expression of the nerve cell phenotype is orchestrated by the REST/NRSF transcription repressor, working on hundreds of genes recognized at a specific regulatory binding sequence. Most PC12 clones, the most frequently employed neuronal model, maintain low levels of REST; however a few, defective of neurosecretion, express high levels. To investigate the role of REST in Ca2+ signalling we studied the [Ca2+](i) changes in single cells of four clones, two wild-type and two defective, pre-treated for 5 days with NGF. We focused on Ca2+ influxes induced by depolarization and ATP. Only a subpopulation ( approximately 15%) of the defective, high REST cells responded to depolarization (Ca(V) expression approximately 10%). The ATP-induced intracellular Ca2+ release was little changed, whereas influx via ionotropic P2X receptors was decreased, in agreement with the decreased expression of P2X2 receptors. The percentage of defective cells expressing store-operated calcium entry (SOCE) following ATP stimulation was also lower. The responses of the defective clones were little affected by their differentiated state. In conclusion, our results revealed important new aspects of REST control of Ca2+ homeostasis, of potential physiological importance. The mechanisms of this control remain to be investigated.
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Affiliation(s)
- P Ariano
- Department of Animal and Human Biology, University of Turin, via Accademia Albertina 13, I-10123 and NIS Centre of Excellence, Turin, Italy
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23
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Friedman LK, Segal M. Early exposure of cultured hippocampal neurons to excitatory amino acids protects from later excitotoxicity. Int J Dev Neurosci 2009; 28:195-205. [DOI: 10.1016/j.ijdevneu.2009.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 09/10/2009] [Accepted: 11/05/2009] [Indexed: 10/20/2022] Open
Affiliation(s)
- Linda K. Friedman
- Neuroscience DepartmentNew York College of Osteopathic Medicine/New York Institute of TechnologyNorthern BoulevardOld WestburyNY11568United States
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Repeated 4-aminopyridine induced seizures diminish the efficacy of glutamatergic transmission in the neocortex. Exp Neurol 2009; 219:136-45. [DOI: 10.1016/j.expneurol.2009.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 05/04/2009] [Accepted: 05/07/2009] [Indexed: 11/20/2022]
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25
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Rylski M, Amborska R, Zybura K, Mioduszewska B, Michaluk P, Jaworski J, Kaczmarek L. Yin Yang 1 is a critical repressor of matrix metalloproteinase-9 expression in brain neurons. J Biol Chem 2008; 283:35140-53. [PMID: 18940814 DOI: 10.1074/jbc.m804540200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Membrane depolarization controls long lasting adaptive neuronal changes in brain physiology and pathology. Such responses are believed to be gene expression-dependent. Notably, however, only a couple of gene repressors active in nondepolarized neurons have been described. In this study, we show that in the unstimulated rat hippocampus in vivo, as well as in the nondepolarized brain neurons in primary culture, the transcriptional regulator Yin Yang 1 (YY1) is bound to the proximal Mmp-9 promoter and strongly represses Mmp-9 transcription. Furthermore, we demonstrate that monoubiquitinated and CtBP1 (C-terminal binding protein 1)-bound YY1 regulates Mmp-9 mRNA synthesis in rat brain neurons controlling its transcription apparently via HDAC3-dependent histone deacetylation. In conclusion, our data suggest that YY1 exerts, via epigenetic mechanisms, a control over neuronal expression of MMP-9. Because MMP-9 has recently been shown to play a pivotal role in physiological and pathological neuronal plasticity, YY1 may be implicated in these phenomena as well.
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Affiliation(s)
- Marcin Rylski
- Department of Molecular and Cellular Neurobiology, Nencki Institute, Pasteura 3, 02-093 Warsaw, Poland.
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26
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D’Alessandro R, Klajn A, Stucchi L, Podini P, Malosio ML, Meldolesi J. Expression of the neurosecretory process in pc12 cells is governed by rest. J Neurochem 2008; 105:1369-83. [DOI: 10.1111/j.1471-4159.2008.05259.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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27
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Mukherjee P, Thomas S, Pasinetti GM. Complement anaphylatoxin C5a neuroprotects through regulation of glutamate receptor subunit 2 in vitro and in vivo. J Neuroinflammation 2008; 5:5. [PMID: 18230183 PMCID: PMC2246107 DOI: 10.1186/1742-2094-5-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 01/29/2008] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The complement system is thought to be involved in the pathogenesis of numerous neurological diseases. We previously reported that pre-treatment of murine cortico-hippocampal neuronal cultures with the complement derived anaphylatoxin C5a, protects against glutamate mediated apoptosis. Our present study with C5a receptor knock out (C5aRKO) mice corroborates that the deficiency of C5a renders C5aRKO mouse more susceptible to apoptotic injury in vivo. In this study we explored potential upstream mechanisms involved in C5a mediated neuroprotection in vivo and in vitro. METHODS Based on evidence suggesting that reduced expression of glutamate receptor subunit 2 (GluR2) may influence apoptosis in neurons, we studied the effect of human recombinant C5a on GluR2 expression in response to glutamate neurotoxicity. Glutamate analogs were injected into C5aRKO mice or used to treat in vitro neuronal culture and GluR2 expression were assessed in respect with cell death. RESULTS In C5aRKO mice we found that the neurons are more susceptible to excitotoxicity resulting in apoptotic injury in the absence of the C5a receptor compared to WT control mice. Our results suggest that C5a protects against apoptotic pathways in neurons in vitro and in vivo through regulation of GluR2 receptor expression. CONCLUSION Complement C5a neuroprotects through regulation of GluR2 receptor subunit.
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Affiliation(s)
- Piali Mukherjee
- Department of Psychiatry, Mount Sinai School of Medicine, 1 Gustav L,, Levy Place, New York, NY 10029, USA.
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