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Ruzicka WB, Subburaju S, Benes FM. Circuit- and Diagnosis-Specific DNA Methylation Changes at γ-Aminobutyric Acid-Related Genes in Postmortem Human Hippocampus in Schizophrenia and Bipolar Disorder. JAMA Psychiatry 2015; 72:541-51. [PMID: 25738424 PMCID: PMC5547581 DOI: 10.1001/jamapsychiatry.2015.49] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
IMPORTANCE Dysfunction related to γ-aminobutyric acid (GABA)-ergic neurotransmission in the pathophysiology of major psychosis has been well established by the work of multiple groups across several decades, including the widely replicated downregulation of GAD1. Prior gene expression and network analyses within the human hippocampus implicate a broader network of genes, termed the GAD1 regulatory network, in regulation of GAD1 expression. Several genes within this GAD1 regulatory network show diagnosis- and sector-specific expression changes within the circuitry of the hippocampus, influencing abnormal GAD1 expression in schizophrenia and bipolar disorder. OBJECTIVE To investigate the hypothesis that aberrant DNA methylation contributes to circuit- and diagnosis-specific abnormal expression of GAD1 regulatory network genes in psychotic illness. DESIGN, SETTING, AND PARTICIPANTS This epigenetic association study targeting GAD1 regulatory network genes was conducted between July 1, 2012, and June 30, 2014. Postmortem human hippocampus tissue samples were obtained from 8 patients with schizophrenia, 8 patients with bipolar disorder, and 8 healthy control participants matched for age, sex, postmortem interval, and other potential confounds from the Harvard Brain Tissue Resource Center, McLean Hospital, Belmont, Massachusetts. We extracted DNA from laser-microdissected stratum oriens tissue of cornu ammonis 2/3 (CA2/3) and CA1 postmortem human hippocampus, bisulfite modified it, and assessed it with the Infinium HumanMethylation450 BeadChip (Illumina, Inc). The subset of CpG loci associated with GAD1 regulatory network genes was analyzed in R version 3.1.0 software (R Foundation) using the minfi package. Findings were validated using bisulfite pyrosequencing. MAIN OUTCOMES AND MEASURES Methylation levels at 1308 GAD1 regulatory network-associated CpG loci were assessed both as individual sites to identify differentially methylated positions and by sharing information among colocalized probes to identify differentially methylated regions. RESULTS A total of 146 differentially methylated positions with a false detection rate lower than 0.05 were identified across all 6 groups (2 circuit locations in each of 3 diagnostic categories), and 54 differentially methylated regions with P < .01 were identified in single-group comparisons. Methylation changes were enriched in MSX1, CCND2, and DAXX at specific loci within the hippocampus of patients with schizophrenia and bipolar disorder. CONCLUSIONS AND RELEVANCE This work demonstrates diagnosis- and circuit-specific DNA methylation changes at a subset of GAD1 regulatory network genes in the human hippocampus in schizophrenia and bipolar disorder. These genes participate in chromatin regulation and cell cycle control, supporting the concept that the established GABAergic dysfunction in these disorders is related to disruption of GABAergic interneuron physiology at specific circuit locations within the human hippocampus.
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Affiliation(s)
- W. Brad Ruzicka
- Program in Structural and Molecular Neuroscience, McLean Hospital, Belmont, Massachusetts,Department of Psychiatry, Harvard Medical School, Boston, Massachusetts
| | - Sivan Subburaju
- Program in Structural and Molecular Neuroscience, McLean Hospital, Belmont, Massachusetts,Department of Psychiatry, Harvard Medical School, Boston, Massachusetts
| | - Francine M. Benes
- Program in Structural and Molecular Neuroscience, McLean Hospital, Belmont, Massachusetts,Department of Psychiatry, Harvard Medical School, Boston, Massachusetts,Program in Neuroscience, Harvard Medical School, Boston, Massachusetts
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Alelú-Paz R, González-Corpas A, Ashour N, Escanilla A, Monje A, Guerrero Márquez C, Algora Weber M, Ropero S. DNA methylation pattern of gene promoters of major neurotransmitter systems in older patients with schizophrenia with severe and mild cognitive impairment. Int J Geriatr Psychiatry 2015; 30:558-65. [PMID: 25044034 DOI: 10.1002/gps.4182] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 06/27/2014] [Accepted: 07/02/2014] [Indexed: 12/22/2022]
Abstract
OBJECTIVE To analyze, in older patients with schizophrenia, the methylation status of a set of genes associated with the pathophysiology of the disorder but including anatomical, clinical, and cognitive criteria in the experimental design that, in conjunction with the epigenetic status of specific genes, allows us to derive an integrative model. METHOD This study included 29 human brain samples from older schizophrenic patients with severe and mild cognitive impairment. We administered a comprehensive battery of neurocognitive tests to determine the size of the impairment across different cognitive domains. We focused our study on the analysis of the methylation pattern of 19 genes of major neurotransmitter systems using methylation-specific PCR and bisulfite genomic sequencing. RESULTS Our results highlight an absence of hypermethylation and hypomethylation in older patients with schizophrenia and in healthy controls, irrespective of the degree of the cognitive deficit measured in the neuropsychological assessment (Fisher's exact test; p<0.05). CONCLUSION mRNA or protein expression level differences in genes of major neurotransmitter systems that are known to be altered in schizophrenia must be because of regulatory mechanisms other than the DNA methylation of its promoter regions, although our results highlight the idea that the analysis of the epigenetic mechanisms involved in schizophrenia represents a new approach that has the possibility of uncovering molecular mechanisms of dysregulated gene expression in this complex disorder.
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Affiliation(s)
- Raúl Alelú-Paz
- Department of Medicine and Medical Specialities, School of Medicine, University of Alcalá, Madrid, Spain; Department of Physiology, Biochemistry and Molecular Biology, School of Medicine, University of Alcalá, Madrid, Spain
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Dong E, Dzitoyeva SG, Matrisciano F, Tueting P, Grayson DR, Guidotti A. Brain-derived neurotrophic factor epigenetic modifications associated with schizophrenia-like phenotype induced by prenatal stress in mice. Biol Psychiatry 2015; 77:589-96. [PMID: 25444166 PMCID: PMC4333020 DOI: 10.1016/j.biopsych.2014.08.012] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 07/31/2014] [Accepted: 08/19/2014] [Indexed: 12/22/2022]
Abstract
BACKGROUND Prenatal stress (PRS) is considered a risk factor for several neurodevelopmental disorders including schizophrenia (SZ). An animal model involving restraint stress of pregnant mice suggests that PRS induces epigenetic changes in specific GABAergic and glutamatergic genes likely to be implicated in SZ, including the gene for brain-derived neurotrophic factor (BDNF). METHODS Studying adult offspring of pregnant mice subjected to PRS, we explored the long-term effects of PRS on behavior and on the expression of key chromatin remodeling factors including DNA methyltransferase 1, ten-eleven-translocation hydroxylases, methyl CpG binding protein 2, histone deacetylases, and histone methyltransferases and demethylase in the frontal cortex and hippocampus. We also measured the expression of BDNF. RESULTS Adult PRS offspring demonstrate behavioral abnormalities suggestive of SZ and molecular changes similar to changes seen in postmortem brains of patients with SZ. This includes a significant increase in DNA methyltransferase 1 and ten-eleven-translocation hydroxylase 1 in the frontal cortex and hippocampus but not in cerebellum; no changes in histone deacetylases, histone methyltransferases and demethylases, or methyl CpG binding protein 2, and a significant decrease in Bdnf messenger RNA variants. The decrease of the corresponding Bdnf transcript level was accompanied by an enrichment of 5-methylcytosine and 5-hydroxymethylcytosine at Bdnf gene regulatory regions. In addition, the expression of Bdnf transcripts (IV and IX) correlated positively with social approach in both PRS mice and nonstressed mice. CONCLUSIONS Because patients with psychosis and PRS mice show similar epigenetic signature, PRS mice may be a suitable model for understanding the behavioral and molecular epigenetic changes observed in patients with SZ.
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Affiliation(s)
- Erbo Dong
- Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois.
| | - Svetlana G. Dzitoyeva
- The Psychiatric Institute, Department of Psychiatry, College of Medicine,0 University of Illinois at Chicago, 1601 W. Taylor St. Chicago. IL. 60612
| | - Francesco Matrisciano
- The Psychiatric Institute, Department of Psychiatry, College of Medicine,0 University of Illinois at Chicago, 1601 W. Taylor St. Chicago. IL. 60612
| | - Patricia Tueting
- The Psychiatric Institute, Department of Psychiatry, College of Medicine,0 University of Illinois at Chicago, 1601 W. Taylor St. Chicago. IL. 60612
| | - Dennis R. Grayson
- The Psychiatric Institute, Department of Psychiatry, College of Medicine,0 University of Illinois at Chicago, 1601 W. Taylor St. Chicago. IL. 60612
| | - Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, College of Medicine,0 University of Illinois at Chicago, 1601 W. Taylor St. Chicago. IL. 60612
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Zong X, Hu M, Li Z, Cao H, Chen X, Tang J. DNA methylation in schizophrenia: progress and challenges. Sci Bull (Beijing) 2015. [DOI: 10.1007/s11434-014-0690-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Schmidt MJ, Mirnics K. Neurodevelopment, GABA system dysfunction, and schizophrenia. Neuropsychopharmacology 2015; 40:190-206. [PMID: 24759129 PMCID: PMC4262918 DOI: 10.1038/npp.2014.95] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/03/2014] [Accepted: 04/11/2014] [Indexed: 02/07/2023]
Abstract
The origins of schizophrenia have eluded clinicians and researchers since Kraepelin and Bleuler began documenting their findings. However, large clinical research efforts in recent decades have identified numerous genetic and environmental risk factors for schizophrenia. The combined data strongly support the neurodevelopmental hypothesis of schizophrenia and underscore the importance of the common converging effects of diverse insults. In this review, we discuss the evidence that genetic and environmental risk factors that predispose to schizophrenia disrupt the development and normal functioning of the GABAergic system.
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Affiliation(s)
- Martin J Schmidt
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
| | - Karoly Mirnics
- Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN, USA
- Department of Psychiatry, University of Szeged, Szeged, Hungary
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Abstract
Epigenetics is the study of chromatin-the physical material that forms chromosomes, composed of DNA wound around specialized histone proteins-and of how the modification of chromatin acts to establish stable states of gene expression in a cell-specific manner. Chromatin is regulated through three mechanisms: DNA methylation, histone modification, and RNA interference. These basic biological processes form the molecular interface between the genome and the environment, contributing to the regulation of gene expression in health and disease. Investigation of epigenetic mechanisms is yielding exciting insights in many areas of medicine, and a large and rapidly growing literature describes epigenetics as central to many aspects of the pathophysiology of psychotic disorders. This article first discusses speculative points as to why the mechanisms of epigenetics may be satisfying explanatory mechanisms in the etiology of psychotic disorders, then details emerging experimental evidence of roles for the three types of epigenetic mechanisms in these illnesses, and finally discusses these mechanisms as potentially compelling areas of research for the development of future treatments.
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Horváth S, Mirnics K. Schizophrenia as a disorder of molecular pathways. Biol Psychiatry 2015; 77:22-8. [PMID: 24507510 PMCID: PMC4092052 DOI: 10.1016/j.biopsych.2014.01.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 01/02/2014] [Accepted: 01/05/2014] [Indexed: 12/21/2022]
Abstract
Over the last decade, transcriptome studies of postmortem tissue from subjects with schizophrenia revealed that synaptic, mitochondrial, immune system, gamma-aminobutyric acidergic, and oligodendrocytic changes are all integral parts of the disease process. The combined genetic and transcriptomic studies argue that the molecular underpinnings of the disease are even more varied than the symptomatic diversity of schizophrenia. Ultimately, to decipher the pathophysiology of human disorders in general, we will need to understand the function of hundreds of genes and regulatory elements in our genome and the consequences of their overexpression and reduced expression in a developmental context. Furthermore, integration of knowledge from various data sources remains a monumental challenge that has to be systematically addressed in the upcoming decades. In the end, our success in interpreting the molecular changes in schizophrenia will depend on our ability to understand the biology using innovative ideas and cannot depend on the hope of developing novel, more powerful technologies.
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Affiliation(s)
- Szatmár Horváth
- Department of Psychiatry; Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Károly Mirnics
- Department of Psychiatry; Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee; Department of Psychiatry, University of Szeged, Szeged, Hungary.
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Numata S, Ye T, Herman M, Lipska BK. DNA methylation changes in the postmortem dorsolateral prefrontal cortex of patients with schizophrenia. Front Genet 2014; 5:280. [PMID: 25206360 PMCID: PMC4144343 DOI: 10.3389/fgene.2014.00280] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 07/31/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Schizophrenia is a complex psychiatric disorder with a lifetime morbidity rate of 0.5-1.0%. The pathophysiology of schizophrenia still remains obscure. Accumulating evidence indicates that DNA methylation, which is the addition of a methyl group to the cytosine in a CpG dinucleotide, might play an important role in the pathogenesis of schizophrenia. METHODS To gain further insight into the molecular mechanisms underlying schizophrenia, a genome-wide DNA methylation profiling (27,578 CpG dinucleotides spanning 14,495 genes) of the human dorsolateral prefrontal cortex (DLPFC) was conducted in a large cohort (n = 216) of well characterized specimens from individuals with schizophrenia and non-psychiatric controls, combined with an analysis of genetic variance at ~880,000 SNPs. RESULTS Aberrant DNA methylation in schizophrenia was identified at 107 CpG sites at 5% Bonferroni correction (p < 1.99 × 10(-6)). Of these significantly altered sites, hyper-DNA methylation was observed at 79 sites (73.8%), mostly in the CpG islands (CGIs) and in the regions flanking CGIs (CGI: 31 sites; CGI shore: 35 sites; CGI shelf: 3 sites). Furthermore, a large number of cis-methylation quantitative trait loci (mQTL) were identified, including associations with risk SNPs implicated in schizophrenia. CONCLUSIONS These results suggest that altered DNA methylation might be involved in the pathophysiology and/or treatment of schizophrenia, and that a combination of epigenetic and genetic approaches will be useful to understanding the molecular mechanism of this complex disorder.
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Affiliation(s)
- Shusuke Numata
- Human Brain Collection Core, National Institute of Mental Health, National Institutes of Health Bethesda, MD, USA ; Department of Psychiatry, Course of Integrated Brain Sciences, Medical Informatics, Institute of Health Biosciences, The University of Tokushima Tokushima, Japan
| | - Tianzhang Ye
- The Lieber Institute for Brain Development, Johns Hopkins University Medical Center Baltimore, MD, USA
| | - Mary Herman
- Human Brain Collection Core, National Institute of Mental Health, National Institutes of Health Bethesda, MD, USA
| | - Barbara K Lipska
- Human Brain Collection Core, National Institute of Mental Health, National Institutes of Health Bethesda, MD, USA
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Epigenetic mechanisms in the development of behavior: advances, challenges, and future promises of a new field. Dev Psychopathol 2014; 25:1279-91. [PMID: 24342840 DOI: 10.1017/s0954579413000618] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the past decade, there have been exciting advances in the field of behavioral epigenetics that have provided new insights into a biological basis of neural and behavioral effects of gene-environment interactions. It is now understood that changes in the activity of genes established through epigenetic alterations occur as a consequence of exposure to environmental adversity, social stress, and traumatic experiences. DNA methylation in particular has thus emerged as a leading candidate biological pathway linking gene-environment interactions to long-term and even multigenerational trajectories in behavioral development, including the vulnerability and resilience to psychopathology. This paper discusses what we have learned from research using animal models and from studies in which the translation of these findings has been made to humans. Studies concerning the significance of DNA methylation alterations in outcomes associated with stress exposure later in life and dysfunction in the form of neuropsychiatric disorders are highlighted, and several avenues of future research are suggested that promise to advance our understanding of epigenetics both as a mechanism by which the environment can contribute to the development of psychiatric disorders and as an avenue for more effective intervention and treatment strategies.
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Davis J, Moylan S, Harvey BH, Maes M, Berk M. Neuroprogression in schizophrenia: Pathways underpinning clinical staging and therapeutic corollaries. Aust N Z J Psychiatry 2014; 48:512-29. [PMID: 24803587 DOI: 10.1177/0004867414533012] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Whilst dopaminergic dysfunction remains a necessary component involved in the pathogenesis of schizophrenia, our current pharmacological armoury of dopamine antagonists does little to control the negative symptoms of schizophrenia. This suggests other pathological processes must be implicated. This paper aims to elaborate on such theories. METHODS Data for this review were sourced from the electronic database PUBMED, and was not limited by language or date of publication. RESULTS It has been suggested that multiple 'hits' may be required to unveil the clinical syndrome in susceptible individuals. Such hits potentially first occur in utero, leading to neuronal disruption, epigenetic changes and the establishment of an abnormal inflammatory response. The development of schizophrenia may therefore potentially be viewed as a neuroprogressive response to these early stressors, driven on by changes in tryptophan catabolite (TRYCAT) metabolism, reactive oxygen species handling and N-methyl d-aspartate (NMDA) circuitry. Given the potential for such progression over time, it is prudent to explore the new treatment strategies which may be implemented before such changes become established. CONCLUSIONS Outside of the dopaminergic model, the potential pathogenesis of schizophrenia has yet to be fully elucidated, but common themes include neuropil shrinkage, the development of abnormal neuronal circuitry, and a chronic inflammatory state which further disrupts neuronal function. Whilst some early non-dopaminergic treatments show promise, none have yet to be fully studied in appropriately structured randomized controlled trials and they remain little more than potential attractive targets.
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Affiliation(s)
- Justin Davis
- IMPACT Strategic Research Centre, Deakin University, School of Medicine, Barwon Health, Geelong, Australia
| | - Steven Moylan
- IMPACT Strategic Research Centre, Deakin University, School of Medicine, Barwon Health, Geelong, Australia
| | - Brian H Harvey
- Division of Pharmacology, and Center of Excellence for Pharmaceutical Sciences, School of Pharmacy, North West University, Potchefstroom, South Africa
| | - Michael Maes
- IMPACT Strategic Research Centre, Deakin University, School of Medicine, Barwon Health, Geelong, Australia Department of Psychiatry, Chulalongkorn University, Bangkok, Thailand
| | - Michael Berk
- IMPACT Strategic Research Centre, Deakin University, School of Medicine, Barwon Health, Geelong, Australia Orygen Youth Health Research Centre, Parkville, Australia Centre of Youth Mental Health, University of Melbourne, Parkville, Australia Florey Institute for Neuroscience and Mental Health, University of Melbourne, Parkville, Australia University of Melbourne, Department of Psychiatry, Royal Melbourne Hospital, Parkville, Australia
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Guidotti A, Auta J, Davis JM, Dong E, Gavin DP, Grayson DR, Sharma RP, Smith RC, Tueting P, Zhubi A. Toward the identification of peripheral epigenetic biomarkers of schizophrenia. J Neurogenet 2014; 28:41-52. [PMID: 24702539 DOI: 10.3109/01677063.2014.892485] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Schizophrenia (SZ) is a heritable, nonmendelian, neurodevelopmental disorder in which epigenetic dysregulation of the brain genome plays a fundamental role in mediating the clinical manifestations and course of the disease. The authors recently reported that two enzymes that belong to the dynamic DNA methylation/demethylation network-DNMT (DNA methyltransferase) and TET (ten-eleven translocase; 5-hydroxycytosine translocator)-are abnormally increased in corticolimbic structures of SZ postmortem brain, suggesting a causal relationship between clinical manifestations of SZ and changes in DNA methylation and in the expression of SZ candidate genes (e.g., brain-derived neurotrophic factor [BDNF], glucocorticoid receptor [GCR], glutamic acid decarboxylase 67 [GAD67], reelin). Because the clinical manifestations of SZ typically begin with a prodrome followed by a first episode in adolescence with subsequent deterioration, it is obvious that the natural history of this disease cannot be studied only in postmortem brain. Hence, the focus is currently shifting towards the feasibility of studying epigenetic molecular signatures of SZ in blood cells. Initial studies show a significant enrichment of epigenetic changes in lymphocytes in gene networks directly relevant to psychiatric disorders. Furthermore, the expression of DNA-methylating/demethylating enzymes and SZ candidate genes such as BDNF and GCR are altered in the same direction in both brain and blood lymphocytes. The coincidence of these changes in lymphocytes and brain supports the hypothesis that common environmental or genetic risk factors are operative in altering the epigenetic components involved in orchestrating transcription of specific genes in brain and peripheral tissues. The identification of DNA methylation signatures for SZ in peripheral blood cells of subjects with genetic and clinical high risk would clearly have potential for the diagnosis of SZ early in its course and would be invaluable for initiating early intervention and individualized treatment plans.
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Affiliation(s)
- A Guidotti
- Psychiatric Institute, Department of Psychiatry, School of Medicine, University of Illinois , Chicago, Chicago, Illinois , USA
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Fass DM, Schroeder FA, Perlis RH, Haggarty SJ. Epigenetic mechanisms in mood disorders: targeting neuroplasticity. Neuroscience 2014; 264:112-30. [PMID: 23376737 PMCID: PMC3830721 DOI: 10.1016/j.neuroscience.2013.01.041] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 01/19/2013] [Indexed: 12/22/2022]
Abstract
Developing novel therapeutics and diagnostic tools based upon an understanding of neuroplasticity is critical in order to improve the treatment and ultimately the prevention of a broad range of nervous system disorders. In the case of mood disorders, such as major depressive disorder (MDD) and bipolar disorder (BPD), where diagnoses are based solely on nosology rather than pathophysiology, there exists a clear unmet medical need to advance our understanding of the underlying molecular mechanisms and to develop fundamentally new mechanism experimental medicines with improved efficacy. In this context, recent preclinical molecular, cellular, and behavioral findings have begun to reveal the importance of epigenetic mechanisms that alter chromatin structure and dynamically regulate patterns of gene expression that may play a critical role in the pathophysiology of mood disorders. Here, we will review recent advances involving the use of animal models in combination with genetic and pharmacological probes to dissect the underlying molecular mechanisms and neurobiological consequence of targeting this chromatin-mediated neuroplasticity. We discuss evidence for the direct and indirect effects of mood stabilizers, antidepressants, and antipsychotics, among their many other effects, on chromatin-modifying enzymes and on the epigenetic state of defined genomic loci, in defined cell types and in specific regions of the brain. These data, as well as findings from patient-derived tissue, have also begun to reveal alterations of epigenetic mechanisms in the pathophysiology and treatment of mood disorders. We summarize growing evidence supporting the notion that selectively targeting chromatin-modifying complexes, including those containing histone deacetylases (HDACs), provides a means to reversibly alter the acetylation state of neuronal chromatin and beneficially impact neuronal activity-regulated gene transcription and mood-related behaviors. Looking beyond current knowledge, we discuss how high-resolution, whole-genome methodologies, such as RNA-sequencing (RNA-Seq) for transcriptome analysis and chromatin immunoprecipitation-sequencing (ChIP-Seq) for analyzing genome-wide occupancy of chromatin-associated factors, are beginning to provide an unprecedented view of both specific genomic loci as well as global properties of chromatin in the nervous system. These methodologies when applied to the characterization of model systems, including those of patient-derived induced pluripotent cell (iPSC) and induced neurons (iNs), will greatly shape our understanding of epigenetic mechanisms and the impact of genetic variation on the regulatory regions of the human genome that can affect neuroplasticity. Finally, we point out critical unanswered questions and areas where additional data are needed in order to better understand the potential to target mechanisms of chromatin-mediated neuroplasticity for novel treatments of mood and other psychiatric disorders.
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Affiliation(s)
- D M Fass
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Reseach, 185 Cambridge Street, Boston, MA 02114, USA; Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - F A Schroeder
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Reseach, 185 Cambridge Street, Boston, MA 02114, USA; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Department of Radiology, Harvard Medical School, 149, 13th Street, Charlestown, MA 02129, USA
| | - R H Perlis
- Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Research, 185 Cambridge Street, Boston, MA 02114, USA
| | - S J Haggarty
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Reseach, 185 Cambridge Street, Boston, MA 02114, USA; Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142, USA; Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Research, 185 Cambridge Street, Boston, MA 02114, USA.
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Romano E, De Angelis F, Ulbrich L, De Jaco A, Fuso A, Laviola G. Nicotine exposure during adolescence: cognitive performance and brain gene expression in adult heterozygous reeler mice. Psychopharmacology (Berl) 2014; 231:1775-87. [PMID: 24337025 DOI: 10.1007/s00213-013-3388-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 11/30/2013] [Indexed: 12/11/2022]
Abstract
RATIONALE We have recently reported nicotine-induced stimulation of reelin and glutamic acid decarboxylase 67 (GAD67) mRNA expression levels in the brain of heterozygous reeler mice (HRM), a putative animal model for the study of symptoms relevant to major behavioral disorders. OBJECTIVES We aimed to evaluate long-term behavioral effects and brain molecular changes as a result of adaptations to nicotine exposure in the developing HRM males. METHODS Adolescent mice (pnd 37-42) were exposed to oral nicotine (10 mg/l) in a 6-day free-choice drinking schedule. As expected, no differences in total nicotine intake between WT (wild-type) mice and HRM were found. RESULTS Long-term behavioral effects and brain molecular changes, as a consequence of nicotine exposure during adolescence, were only evidenced in HRM. Indeed, HRM perseverative exploratory behavior and poor cognitive performance were modulated to WT levels by subchronic exposure to nicotine during development. Furthermore, the expected reduction in the expression of mRNA of reelin and GAD67 in behaviorally relevant brain areas of HRM appeared persistently restored by nicotine. For brain-derived neurotrophic factor (BDNF) mRNA expression, no genotype-dependent changes appeared. However, expression levels were increased by previous nicotine in brains from both genotypes. The mRNA encoding for nicotine receptor subunits (α7, β2 and α4) did not differ between genotypes and as a result of previous nicotine exposure. CONCLUSION These findings support the hypothesis of pre-existing vulnerability (based on haploinsufficiency of reelin) to brain and behavioral disorders and regulative short- and long-term effects associated with nicotine modulation.
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Affiliation(s)
- Emilia Romano
- Section of Behavioural Neuroscience, Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
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Horváth S, Mirnics K. Immune system disturbances in schizophrenia. Biol Psychiatry 2014; 75:316-23. [PMID: 23890736 PMCID: PMC3841236 DOI: 10.1016/j.biopsych.2013.06.010] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 06/06/2013] [Accepted: 06/19/2013] [Indexed: 12/12/2022]
Abstract
Epidemiological, genetic, transcriptome, postmortem, peripheral biomarker, and therapeutic studies of schizophrenia all point to a dysregulation of both innate and adaptive immune systems in the disease, and it is likely that these immune changes actively contribute to disease symptoms. Gene expression disturbances in the brain of subjects with schizophrenia show complex, region-specific changes with consistently replicated and potentially interdependent induction of serpin peptidase inhibitor, clade A member 3 (SERPINA3) and interferon inducible transmembrane protein (IFITM) family transcripts in the prefrontal cortex. Recent data suggest that IFITM3 expression is a critical mediator of maternal immune activation. Because the IFITM gene family is primarily expressed in the endothelial cells and meninges, and because the meninges play a critical role in interneuron development, we suggest that these two non-neuronal cell populations might play an important role in the disease pathophysiology. Finally, we propose that IFITM3 in particular might be a novel, appealing, knowledge-based drug target for treatment of schizophrenia.
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Affiliation(s)
- Szatmár Horváth
- Department of Psychiatry, Vanderbilt University, Nashville, TN 37232, USA,Department of Psychiatry, University of Szeged, 6725 Szeged, Hungary
| | - Károly Mirnics
- Department of Psychiatry, Vanderbilt University, Nashville, Tennessee; Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee; Department of Psychiatry, University of Szeged, 6725 Szeged, Hungary.
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Gavin DP, Floreani C. Epigenetics of schizophrenia: an open and shut case. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 115:155-201. [PMID: 25131545 DOI: 10.1016/b978-0-12-801311-3.00005-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During the last decade and a half, there has been an explosion of data regarding epigenetic changes in schizophrenia. Most initial studies have suggested that schizophrenia is characterized by an overly restrictive chromatin state based on increases in transcription silencing histone modifications and DNA methylation at schizophrenia candidate gene promoters and increases in the expression of enzymes that catalyze their formation. However, recent studies indicate that the pathology is more complex. This complexity may greatly impact pharmacological approaches directed at targeting epigenetic abnormalities in schizophrenia. The current review explores epigenetic studies of schizophrenia and what this can tell us about the underlying pathophysiology. We hypothesize based on recent studies that it is also plausible that drugs that further restrict chromatin may be efficacious.
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Affiliation(s)
- David P Gavin
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA.
| | - Christina Floreani
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
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66
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Guidotti A, Dong E, Tueting P, Grayson DR. Modeling the molecular epigenetic profile of psychosis in prenatally stressed mice. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 128:89-101. [PMID: 25410542 PMCID: PMC4283473 DOI: 10.1016/b978-0-12-800977-2.00004-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Based on postmortem brain studies, our overarching epigenetic hypothesis is that chronic schizophrenia (SZ) is a psychopathological condition involving dysregulation of the dynamic equilibrium among DNA methylation/demethylation network components and the expression of SZ target genes, including GABAergic and glutamatergic genes. SZ has a natural course, starting with a prodromal phase, a first episode that occurs in adolescents or in young adults, and later deterioration over the adult years. Hence, the epigenetic status at each neurodevelopmental stage of the disease cannot be studied just in postmortem brain of chronic SZ patients, but requires the use of neurodevelopmental animal models. We have directed the focus of our research toward studying the epigenetic signature of the SZ brain in the offspring of dams stressed during pregnancy (PRS mice). Adult PRS mice have behavioral deficits reminiscent of behaviors observed in psychotic patients. The adult PRS brain, like that of postmortem chronic SZ patients, is characterized by a significant increase in DNA methyltransferase 1, Tet methylcytosine dioxygenase 1 (TET1), 5-methylcytosine, and 5-hydroxymethylcytosine at SZ candidate gene promoters and a reduction in the expression of glutamatergic and GABAergic genes. In PRS mice, measurements of epigenetic biomarkers for SZ can be assessed at different stages of development with the goal of further elucidating the pathophysiology of this disease and predicting treatment responses at specific stages of the illness, with particular attention to early detection and possibly early intervention.
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Affiliation(s)
- Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Erbo Dong
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Patricia Tueting
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Dennis R Grayson
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
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67
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Zhubi A, Cook EH, Guidotti A, Grayson DR. Epigenetic Mechanisms in Autism Spectrum Disorder. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 115:203-44. [DOI: 10.1016/b978-0-12-801311-3.00006-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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68
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McCullumsmith RE, Hammond JH, Shan D, Meador-Woodruff JH. Postmortem brain: an underutilized substrate for studying severe mental illness. Neuropsychopharmacology 2014; 39:65-87. [PMID: 24091486 PMCID: PMC3857666 DOI: 10.1038/npp.2013.239] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 07/30/2013] [Accepted: 08/02/2013] [Indexed: 02/08/2023]
Abstract
We propose that postmortem tissue is an underutilized substrate that may be used to translate genetic and/or preclinical studies, particularly for neuropsychiatric illnesses with complex etiologies. Postmortem brain tissues from subjects with schizophrenia have been extensively studied, and thus serve as a useful vehicle for illustrating the challenges associated with this biological substrate. Schizophrenia is likely caused by a combination of genetic risk and environmental factors that combine to create a disease phenotype that is typically not apparent until late adolescence. The complexity of this illness creates challenges for hypothesis testing aimed at understanding the pathophysiology of the illness, as postmortem brain tissues collected from individuals with schizophrenia reflect neuroplastic changes from a lifetime of severe mental illness, as well as treatment with antipsychotic medications. While there are significant challenges with studying postmortem brain, such as the postmortem interval, it confers a translational element that is difficult to recapitulate in animal models. On the other hand, data derived from animal models typically provide specific mechanistic and behavioral measures that cannot be generated using human subjects. Convergence of these two approaches has led to important insights for understanding molecular deficits and their causes in this illness. In this review, we discuss the problem of schizophrenia, review the common challenges related to postmortem studies, discuss the application of biochemical approaches to this substrate, and present examples of postmortem schizophrenia studies that illustrate the role of the postmortem approach for generating important new leads for understanding the pathophysiology of severe mental illness.
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Affiliation(s)
| | - John H Hammond
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama-Birmingham, Birmingham, AL, USA
| | - Dan Shan
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama-Birmingham, Birmingham, AL, USA
| | - James H Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama-Birmingham, Birmingham, AL, USA
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69
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Auta J, Smith R, Dong E, Tueting P, Sershen H, Boules S, Lajtha A, Davis J, Guidotti A. DNA-methylation gene network dysregulation in peripheral blood lymphocytes of schizophrenia patients. Schizophr Res 2013; 150:312-8. [PMID: 23938174 PMCID: PMC4121849 DOI: 10.1016/j.schres.2013.07.030] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 07/10/2013] [Accepted: 07/12/2013] [Indexed: 12/22/2022]
Abstract
The epigenetic dysregulation of the brain genome associated with the clinical manifestations of schizophrenia (SZ) includes altered DNA promoter methylation of several candidate genes. We and others have reported that two enzymes that belong to the DNA-methylation/demethylation network pathways-DNMT1 (DNA-methyltransferase) and ten-eleven translocator-1(TET1) methylcytosine deoxygenase are abnormally increased in corticolimbic structures of SZ postmortem brain. The objective of this study was to investigate whether the expression of these components of the DNA-methylation-demethylation pathways known to be altered in the brain of SZ patients are also altered in peripheral blood lymphocytes (PBL). The data show that increases in DNMT1 and TET1 and in glucocorticoid receptor (GCortR) and brain derived neurotrophic factor (BDNF) mRNAs in PBL of SZ patients are comparable to those reported in the brain of SZ patients. The finding that the expressions of DNMT1 and TET1 are increased and SZ candidate genes such as BDNF and GCortR are altered in the same direction in both the brain and PBL together with recent studies showing highly correlated patterns of DNA methylation across the brain and blood, support the hypothesis that a common epigenetic dysregulation may be operative in the brain and peripheral tissues of SZ patients.
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Affiliation(s)
- J. Auta
- Psychiatric Institute, Department of Psychiatry, College of medicine, University of Illinois at Chicago
| | - R.C. Smith
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY,Dept of Psychiatry, New York University School of Medicine, NY, N.Y
| | - E. Dong
- Psychiatric Institute, Department of Psychiatry, College of medicine, University of Illinois at Chicago
| | - P. Tueting
- Psychiatric Institute, Department of Psychiatry, College of medicine, University of Illinois at Chicago
| | - H. Sershen
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY,Dept of Psychiatry, New York University School of Medicine, NY, N.Y
| | - S. Boules
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY
| | - A. Lajtha
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY,Dept of Psychiatry, New York University School of Medicine, NY, N.Y
| | - J. Davis
- Psychiatric Institute, Department of Psychiatry, College of medicine, University of Illinois at Chicago
| | - A. Guidotti
- Psychiatric Institute, Department of Psychiatry, College of medicine, University of Illinois at Chicago
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70
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Jiang Z, Cowell RM, Nakazawa K. Convergence of genetic and environmental factors on parvalbumin-positive interneurons in schizophrenia. Front Behav Neurosci 2013; 7:116. [PMID: 24027504 PMCID: PMC3759852 DOI: 10.3389/fnbeh.2013.00116] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 08/13/2013] [Indexed: 11/13/2022] Open
Abstract
Schizophrenia etiology is thought to involve an interaction between genetic and environmental factors during postnatal brain development. However, there is a fundamental gap in our understanding of the molecular mechanisms by which environmental factors interact with genetic susceptibility to trigger symptom onset and disease progression. In this review, we summarize the most recent findings implicating oxidative stress as one mechanism by which environmental insults, especially early life social stress, impact the development of schizophrenia. Based on a review of the literature and the results of our own animal model, we suggest that environmental stressors such as social isolation render parvalbumin-positive interneurons (PVIs) vulnerable to oxidative stress. We previously reported that social isolation stress exacerbates many of the schizophrenia-like phenotypes seen in a conditional genetic mouse model in which NMDA receptors (NMDARs) are selectively ablated in half of cortical and hippocampal interneurons during early postnatal development (Belforte et al., 2010). We have since revealed that this social isolation-induced effect is caused by impairments in the antioxidant defense capacity in the PVIs in which NMDARs are ablated. We propose that this effect is mediated by the down-regulation of PGC-1α, a master regulator of mitochondrial energy metabolism and anti-oxidant defense, following the deletion of NMDARs (Jiang et al., 2013). Other potential molecular mechanisms underlying redox dysfunction upon gene and environmental interaction will be discussed, with a focus on the unique properties of PVIs.
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Affiliation(s)
- Zhihong Jiang
- Unit on Genetics of Cognition and Behavior, National Institute of Mental Health, NIH Bethesda, MD, USA
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71
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Maćkowiak M, Guzik R, Dudys D, Bator E, Wędzony K. MK-801, a NMDA receptor antagonist, increases phosphorylation of histone H3 in the rat medial prefrontal cortex. Pharmacol Rep 2013; 65:1112-23. [DOI: 10.1016/s1734-1140(13)71469-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 09/20/2013] [Indexed: 02/01/2023]
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72
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Intracellular pathways of antipsychotic combined therapies: implication for psychiatric disorders treatment. Eur J Pharmacol 2013; 718:502-23. [PMID: 23834777 DOI: 10.1016/j.ejphar.2013.06.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Revised: 06/11/2013] [Accepted: 06/21/2013] [Indexed: 01/06/2023]
Abstract
Dysfunctions in the interplay among multiple neurotransmitter systems have been implicated in the wide range of behavioral, emotional and cognitive symptoms displayed by major psychiatric disorders, such as schizophrenia, bipolar disorder or major depression. The complex clinical presentation of these pathologies often needs the use of multiple pharmacological treatments, in particular (1) when monotherapy provides insufficient improvement of the core symptoms; (2) when there are concurrent additional symptoms requiring more than one class of medication and (3) in order to improve tolerability, by using two compounds below their individual dose thresholds to limit side effects. To date, the choice of drug combinations is based on empirical paradigm guided by clinical response. Nonetheless, several preclinical studies have demonstrated that drugs commonly used to treat psychiatric disorders may impact common intracellular target molecules (e.g. Akt/GSK-3 pathway, MAP kinases pathway, postsynaptic density proteins). These findings support the hypothesis that convergence at crucial steps of transductional pathways could be responsible for synergistic effects obtained in clinical practice by the co-administration of those apparently heterogeneous pharmacological compounds. Here we review the most recent evidence on the molecular crossroads in antipsychotic combined therapies with antidepressants, mood stabilizers, and benzodiazepines, as well as with antipsychotics. We first discuss clinical clues and efficacy of such combinations. Then we focus on the pharmacodynamics and on the intracellular pathways underpinning the synergistic, or concurrent, effects of each therapeutic add-on strategy, as well as we also critically appraise how pharmacological research may provide new insights on the putative molecular mechanisms underlying major psychiatric disorders.
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73
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Misiak B, Frydecka D, Piotrowski P, Kiejna A. The multidimensional nature of metabolic syndrome in schizophrenia: lessons from studies of one-carbon metabolism and DNA methylation. Epigenomics 2013; 5:317-29. [DOI: 10.2217/epi.13.22] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Large data sets indicate that the prevalence of metabolic syndrome (MetS) is significantly higher in patients with schizophrenia in comparison with the general population. Given that interactions between genes and the environment may underlie the etiology of MetS in subjects with schizophrenia, it is feasible that epigenetic phenomena can serve as the etiological consensus between genetic and environmental factors. However, there is still a striking scarcity of studies aimed at investigating the role of aberrant DNA methylation in the development of MetS in this group of patients. This article provides an update on the epigenetics of schizophrenia and reviews studies on the role of one-carbon metabolism and aberrant DNA methylation in the development of MetS.
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Affiliation(s)
- Blazej Misiak
- Department of Psychiatry, Wroclaw Medical University, Pasteura 10, 51-367 Wroclaw, Poland.
| | - Dorota Frydecka
- Department of Psychiatry, Wroclaw Medical University, Pasteura 10, 51-367 Wroclaw, Poland
| | - Patryk Piotrowski
- Department of Psychiatry, Wroclaw Medical University, Pasteura 10, 51-367 Wroclaw, Poland
| | - Andrzej Kiejna
- Department of Psychiatry, Wroclaw Medical University, Pasteura 10, 51-367 Wroclaw, Poland
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74
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Kofink D, Boks MP, Timmers HM, Kas MJ. Epigenetic dynamics in psychiatric disorders: Environmental programming of neurodevelopmental processes. Neurosci Biobehav Rev 2013; 37:831-45. [DOI: 10.1016/j.neubiorev.2013.03.020] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/19/2013] [Accepted: 03/27/2013] [Indexed: 12/13/2022]
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75
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Abstract
Knowledge of thalamocortical (TC) processing comes mainly from studying core thalamic systems that project to middle layers of primary sensory cortices. However, most thalamic relay neurons comprise a matrix of cells that are densest in the "nonspecific" thalamic nuclei and usually target layer 1 (L1) of multiple cortical areas. A longstanding hypothesis is that matrix TC systems are crucial for regulating neocortical excitability during changing behavioral states, yet we know almost nothing about the mechanisms of such regulation. It is also unclear whether synaptic and circuit mechanisms that are well established for core sensory TC systems apply to matrix TC systems. Here we describe studies of thalamic matrix influences on mouse prefrontal cortex using optogenetic and in vitro electrophysiology techniques. Channelrhodopsin-2 was expressed in midline and paralaminar (matrix) thalamic neurons, and their L1-projecting TC axons were activated optically. Contrary to conventional views, we found that matrix TC projections to L1 could transmit relatively strong, fast, high-fidelity synaptic signals. L1 TC projections preferentially drove inhibitory interneurons of L1, especially those of the late-spiking subtype, and often triggered feedforward inhibition in both L1 interneurons and pyramidal cells of L2/L3. Responses during repetitive stimulation were far more sustained for matrix than for core sensory TC pathways. Thus, matrix TC circuits appear to be specialized for robust transmission over relatively extended periods, consistent with the sort of persistent activation observed during working memory and potentially applicable to state-dependent regulation of excitability.
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76
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Snyder MA, Gao WJ. NMDA hypofunction as a convergence point for progression and symptoms of schizophrenia. Front Cell Neurosci 2013; 7:31. [PMID: 23543703 PMCID: PMC3608949 DOI: 10.3389/fncel.2013.00031] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 03/11/2013] [Indexed: 01/05/2023] Open
Abstract
Schizophrenia is a disabling mental illness that is now recognized as a neurodevelopmental disorder. It is likely that genetic risk factors interact with environmental perturbations to affect normal brain development and that this altered trajectory results in a combination of positive, negative, and cognitive symptoms. Although the exact pathophysiology of schizophrenia is unknown, the N-methyl-D-aspartate receptor (NMDAR), a major glutamate receptor subtype, has received great attention. Proper expression and regulation of NMDARs in the brain is critical for learning and memory processes as well as cortical plasticity and maturation. Evidence from both animal models and human studies implicates a dysfunction of NMDARs both in disease progression and symptoms of schizophrenia. Furthermore, mutations in many of the known genetic risk factors for schizophrenia suggest that NMDAR hypofunction is a convergence point for schizophrenia. In this review, we discuss how disrupted NMDAR function leads to altered neurodevelopment that may contribute to the progression and development of symptoms for schizophrenia, particularly cognitive deficits. We review the shared signaling pathways among the schizophrenia susceptibility genes DISC1, neuregulin1, and dysbindin, focusing on the AKT/GSK3β pathway, and how their mutations and interactions can lead to NMDAR dysfunction during development. Additionally, we explore what open questions remain and suggest where schizophrenia research needs to move in order to provide mechanistic insight into the cause of NMDAR dysfunction, as well as generate possible new avenues for therapeutic intervention.
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Affiliation(s)
- Melissa A Snyder
- Department of Neurobiology and Anatomy, Drexel University College of Medicine Philadelphia, PA, USA
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77
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Nicotine restores Wt-like levels of reelin and GAD67 gene expression in brain of heterozygous reeler mice. Neurotox Res 2013; 24:205-15. [PMID: 23385624 DOI: 10.1007/s12640-013-9378-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 01/15/2013] [Accepted: 01/21/2013] [Indexed: 12/11/2022]
Abstract
Important reduction of reelin, a neural development- and plasticity-associated protein, and glutamic acid decarboxylase (GAD67) are reported in brains of schizophrenic patients. These individuals are consistently engaged in tobacco smoking and nicotine is thought to alleviate negative behavioral symptoms or cognitive alterations. In mouse brain, nicotine has been shown to reduce GAD67 promoter methylation and increase its transcription. We assessed the effects of administration of nicotine (1 mg/kg s.c.) for 6 days, in male mice heterozygous for reelin (HRM), a putative model for symptoms related to schizophrenia. Expression of reelin, GAD67 and brain-derived neurotrophic factor (BDNF) was measured in different brain areas. RNA expression analysis evidenced genotype-related changes, with a marked reduction in reelin and GAD67 gene expression in prefrontal cortex, hippocampus, cerebellum, and striatum from HRM. Nicotine treatment selectively reversed the HRM-related phenotype in most brain areas and increased BDNF gene expression in cortex and hippocampus of both genotypes. Locomotor performance in their home cage revealed that HRM subjects were characterized by general hyperactivity; with nicotine administration restoring WT-like levels of locomotion. These findings are interpreted within the hypothesis of pre-existing vulnerability (based on haploinsufficiency of reelin) to brain and behavioral disorders and regulative effects associated with nicotine exposure.
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78
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Bostrom JA, Sodhi M. A Look to the Future. Pharmacogenomics 2013. [DOI: 10.1016/b978-0-12-391918-2.00016-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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79
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Grayson DR, Guidotti A. The dynamics of DNA methylation in schizophrenia and related psychiatric disorders. Neuropsychopharmacology 2013; 38:138-66. [PMID: 22948975 PMCID: PMC3521968 DOI: 10.1038/npp.2012.125] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 02/06/2023]
Abstract
Major psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BP) with psychosis (BP+) express a complex symptomatology characterized by positive symptoms, negative symptoms, and cognitive impairment. Postmortem studies of human SZ and BP+ brains show considerable alterations in the transcriptome of a variety of cortical structures, including multiple mRNAs that are downregulated in both inhibitory GABAergic and excitatory pyramidal neurons compared with non-psychiatric subjects (NPS). Several reports show increased expression of DNA methyltransferases in telencephalic GABAergic neurons. Accumulating evidence suggests a critical role for altered DNA methylation processes in the pathogenesis of SZ and related psychiatric disorders. The establishment and maintenance of CpG site methylation is essential during central nervous system differentiation and this methylation has been implicated in synaptic plasticity, learning, and memory. Atypical hypermethylation of candidate gene promoters expressed in GABAergic neurons is associated with transcriptional downregulation of the corresponding mRNAs, including glutamic acid decarboxylase 67 (GAD67) and reelin (RELN). Recent reports indicate that the methylation status of promoter proximal CpG dinucleotides is in a dynamic balance between DNA methylation and DNA hydroxymethylation. Hydroxymethylation and subsequent DNA demethylation is more complex and involves additional proteins downstream of 5-hydroxymethylcytosine, including members of the base excision repair (BER) pathway. Recent advances in our understanding of altered CpG methylation, hydroxymethylation, and active DNA demethylation provide a framework for the identification of new targets, which may be exploited for the pharmacological intervention of the psychosis associated with SZ and possibly BP+.
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Affiliation(s)
- Dennis R Grayson
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
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80
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Nishioka M, Bundo M, Kasai K, Iwamoto K. DNA methylation in schizophrenia: progress and challenges of epigenetic studies. Genome Med 2012; 4:96. [PMID: 23234572 PMCID: PMC3580436 DOI: 10.1186/gm397] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Schizophrenia is a severe psychiatric disease affecting about 1% of the world's population, with significant effects on patients and society. Genetic studies have identified several candidate risk genes or genomic regions for schizophrenia, and epidemiological studies have revealed several environmental risk factors. However, the etiology of schizophrenia still remains largely unknown. Epigenetic mechanisms such as DNA methylation and histone modifications can explain the interaction between genetic and environmental factors at the molecular level, and accumulating evidence suggests that such epigenetic alterations are involved in the pathophysiology of schizophrenia. However, replication studies to validate previous findings and investigations of the causality of epigenetic alterations in schizophrenia are needed. Here, we review epigenetic studies of schizophrenia patients using postmortem brains or peripheral tissues, focusing mainly on DNA methylation. We also highlight the recent progress and challenges in characterizing the potentially complex and dynamic patterns of epigenomic variations. Such studies are expected to contribute to our understanding of schizophrenia etiology and should provide novel opportunities for the development of therapeutic drugs.
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Affiliation(s)
- Masaki Nishioka
- Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 1138655, Japan
- Department of Molecular Psychiatry, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 1138655, Japan
| | - Miki Bundo
- Department of Molecular Psychiatry, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 1138655, Japan
| | - Kiyoto Kasai
- Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 1138655, Japan
| | - Kazuya Iwamoto
- Department of Molecular Psychiatry, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 1138655, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi-shi, Saitama 332-0012, Japan
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81
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Millan MJ. An epigenetic framework for neurodevelopmental disorders: from pathogenesis to potential therapy. Neuropharmacology 2012; 68:2-82. [PMID: 23246909 DOI: 10.1016/j.neuropharm.2012.11.015] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 11/11/2012] [Accepted: 11/22/2012] [Indexed: 12/12/2022]
Abstract
Neurodevelopmental disorders (NDDs) are characterized by aberrant and delayed early-life development of the brain, leading to deficits in language, cognition, motor behaviour and other functional domains, often accompanied by somatic symptoms. Environmental factors like perinatal infection, malnutrition and trauma can increase the risk of the heterogeneous, multifactorial and polygenic disorders, autism and schizophrenia. Conversely, discrete genetic anomalies are involved in Down, Rett and Fragile X syndromes, tuberous sclerosis and neurofibromatosis, the less familiar Phelan-McDermid, Sotos, Kleefstra, Coffin-Lowry and "ATRX" syndromes, and the disorders of imprinting, Angelman and Prader-Willi syndromes. NDDs have been termed "synaptopathies" in reference to structural and functional disturbance of synaptic plasticity, several involve abnormal Ras-Kinase signalling ("rasopathies"), and many are characterized by disrupted cerebral connectivity and an imbalance between excitatory and inhibitory transmission. However, at a different level of integration, NDDs are accompanied by aberrant "epigenetic" regulation of processes critical for normal and orderly development of the brain. Epigenetics refers to potentially-heritable (by mitosis and/or meiosis) mechanisms controlling gene expression without changes in DNA sequence. In certain NDDs, prototypical epigenetic processes of DNA methylation and covalent histone marking are impacted. Conversely, others involve anomalies in chromatin-modelling, mRNA splicing/editing, mRNA translation, ribosome biogenesis and/or the regulatory actions of small nucleolar RNAs and micro-RNAs. Since epigenetic mechanisms are modifiable, this raises the hope of novel therapy, though questions remain concerning efficacy and safety. The above issues are critically surveyed in this review, which advocates a broad-based epigenetic framework for understanding and ultimately treating a diverse assemblage of NDDs ("epigenopathies") lying at the interface of genetic, developmental and environmental processes. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Mark J Millan
- Unit for Research and Discovery in Neuroscience, IDR Servier, 125 chemin de ronde, 78290 Croissy sur Seine, Paris, France.
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82
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Kim SH, Lee HY, Yi H, Ahn YM, Kim YS. Haloperidol induces demethylation and expression of the dual specificity phosphatase 6 gene in MIA PaCa-2 human pancreatic cancer cells. Life Sci 2012; 91:1317-22. [DOI: 10.1016/j.lfs.2012.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 09/18/2012] [Accepted: 10/01/2012] [Indexed: 12/30/2022]
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83
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Effects of transient cerebral ischemia on the expression of DNA methyltransferase 1 in the gerbil hippocampal CA1 region. Neurochem Res 2012; 38:74-81. [PMID: 22987057 DOI: 10.1007/s11064-012-0890-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 08/20/2012] [Accepted: 09/10/2012] [Indexed: 12/25/2022]
Abstract
DNA methylation is a key epigenetic modification of DNA that is catalyzed by DNA methyltransferases (Dnmt). Increasing evidences suggest that DNA methylation in neurons regulates synaptic plasticity as well as neuronal network activity. In the present study, we investigated the changes in DNA methyltransferases 1 (Dnmt1) immunoreactivity and its protein levels in the gerbil hippocampal CA1 region after 5 min of transient global cerebral ischemia. CA1 pyramidal neurons were well stained with NeuN (a neuron-specific soluble nuclear antigen) antibody in the sham-group, Four days after ischemia-reperfusion (I-R), NeuN-positive ((+)) cells were significantly decreased in the stratum pyramidale (SP) of the CA1 region, and many Fluro-Jade B (a marker for neuronal degeneration)(+) cells were observed in the SP. Dnmt1 immunoreactivity was well detected in all the layers of the sham-group. Dnmt1 immunoreactivity was hardly detected only in the stratum pyramidale of the CA1 region from 4 days post-ischemia; however, at these times, Dnmt1 immunoreactivity was newly expressed in GABAergic interneurons or astrocytes in the ischemic CA1 region. In addition, the level of Dnmt1 was lowest at 4 days post-ischemia. In brief, both the Dnmt1 immunoreactivity and protein levels were distinctively decreased in the ischemic CA1 region 4 days after transient cerebral ischemia. These results indicate that the decrease of Dnmt1 expression at 4 days post-ischemia may be related to ischemia-induced delayed neuronal death.
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84
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Guidotti A, Dong E, Gavin DP, Veldic M, Zhao W, Bhaumik DK, Pandey SC, Grayson DR. DNA methylation/demethylation network expression in psychotic patients with a history of alcohol abuse. Alcohol Clin Exp Res 2012; 37:417-24. [PMID: 22958170 DOI: 10.1111/j.1530-0277.2012.01947.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 07/23/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Recent studies suggest that protracted and excessive alcohol use induces an epigenetic dysregulation in human and rodent brains. We recently reported that DNA methylation dynamics are altered in brains of psychotic (PS) patients, including schizophrenia and bipolar disorder patients. Because PS patients are often comorbid with chronic alcohol abuse, we examined whether the altered expression of multiple members of the DNA methylation/demethylation network observed in postmortem brains of PS patients was modified in PS patients with a history of chronic alcohol abuse. METHODS DNA-methyltransferase-1 (DNMT1) mRNA-positive neurons were counted in situ in prefrontal cortex samples obtained from the Harvard Brain Tissue Resource Center, Belmont, MA. 10-11-translocation (TETs 1, 2, 3), apolipoprotein B editing complex enzyme (APOBEC-3C), growth and DNA-damage-inducible protein 45β (GADD45β), and methyl-binding domain protein-4 (MBD4) mRNAs were measured by quantitative real-time polymerase chain reaction in inferior parietal cortical lobule samples obtained from the Stanley Foundation Neuropathology Consortium, Bethesda, MD. RESULTS We observed an increase in DNMT1 mRNA-positive neurons in PS patients compared with non-PS subjects. In addition, there was a pronounced decrease in APOBEC-3C and a pronounced increase in GADD45β and TET1 mRNAs in PS patients with no history of alcohol abuse. In PS patients with a history of chronic alcohol abuse, the numbers of DNMT1-positive neurons were not increased significantly. Furthermore, the decrease in APOBEC-3C mRNA was less pronounced, while the increase in TET1 mRNA had a tendency to be potentiated in those PS patients that were chronic alcohol abusers. GADD45β and MBD4 mRNAs were not influenced by alcohol abuse. The effect of chronic alcohol abuse on DNA methylation/demethylation network enzymes cannot be attributed to confounding demographic variables or to the type and dose of medication used. CONCLUSIONS Based on these results, we hypothesize that PS patients may abuse alcohol as a potential attempt at self-medication to normalize altered DNA methylation/demethylation network pathways. However, before accepting this conclusion, we need to study alterations in the DNA methylation/demethylation pathways and the DNA methylation dynamics in a substantial number of alcoholic PS and non-PS patients. Additional investigation may also be necessary to determine whether the altered DNA methylation dynamics are direct or the consequence of an indirect interaction of alcohol with the neuropathogenetic mechanisms underlying psychosis.
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Affiliation(s)
- Alessandro Guidotti
- Department of Psychiatry, The Psychiatric Institute, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, 60612, USA
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85
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Dong E, Gavin DP, Chen Y, Davis J. Upregulation of TET1 and downregulation of APOBEC3A and APOBEC3C in the parietal cortex of psychotic patients. Transl Psychiatry 2012; 2:e159. [PMID: 22948384 PMCID: PMC3565208 DOI: 10.1038/tp.2012.86] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Increasing evidence suggests that epigenetic dysfunction may account for the alteration of gene transcription present in neuropsychiatric disorders such as schizophrenia (SZ), bipolar disorder (BP) and autism. Here, we studied the expression of the ten-eleven translocation (TET) gene family and activation-induced deaminase/apolipoprotein B mRNA-editing enzymes (AID/APOBEC) in the inferior parietal lobule (IPL) (BA39-40) and the cerebellum of psychotic (PSY) patients, depressed (DEP) patients and nonpsychiatric (CTR) subjects obtained from the Stanley Foundation Neuropathology Consortium Medical Research Institute. These two sets of enzymes have a critical role in the active DNA demethylation pathway. The results show that TET1, but not TET2 and TET3, mRNA and protein expression was increased (two- to threefold) in the IPL of the PSY patients compared with the CTR subjects. TET1 mRNA showed no change in the cerebellum. Consistent with the increase of TET1, the level of 5-hydroxymethylcytosine (5hmC) was elevated in the IPL of PSY patients but not in the other groups. Moreover, higher 5hmC levels were detected at the glutamic acid decarboxylase67 (GAD67) promoter only in the PSY group. This increase was inversely related to the decrease of GAD67 mRNA expression. Of 11 DNA deaminases measured, APOBEC3A mRNA was significantly decreased in the PSY and DEP patients, while APOBEC3C was decreased only in PSY patients. The other APOBEC mRNA studied failed to change. Increased TET1 and decreased APOBEC3A and APOBEC3C found in this study highlight the possible role of altered DNA demethylation mechanisms in the pathophysiology of psychosis.
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Affiliation(s)
- E Dong
- Department of Psychiatry, The Psychiatric Institute, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
| | - D P Gavin
- Department of Psychiatry, The Psychiatric Institute, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Y Chen
- Department of Psychiatry, The Psychiatric Institute, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - J Davis
- Department of Psychiatry, The Psychiatric Institute, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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86
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Kadriu B, Guidotti A, Chen Y, Grayson DR. DNA methyltransferases1 (DNMT1) and 3a (DNMT3a) colocalize with GAD67-positive neurons in the GAD67-GFP mouse brain. J Comp Neurol 2012; 520:1951-64. [PMID: 22134929 DOI: 10.1002/cne.23020] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
DNA methylation is an epigenetic regulatory mechanism commonly associated with transcriptional silencing. DNA methyltransferases (DNMTs) are a family of related proteins that both catalyze the de novo formation of 5-methylcytosine and maintain these methylation marks in cell-specific patterns in virtually all mitotic cells of the body. In the adult brain, methylation occurs in progenitor cells of the neurogenic zones and in postmitotic neurons. Of the DNMTs, DNMT1 and DNMT3a are most highly expressed in postmitotic neurons. While it has been commonly thought all postmitotic neurons and glia express DNMTs at comparable levels, the coexpression of selected DNMTs with markers of distinct neurotransmitter phenotypes has not been previously examined in detail in the mouse. To this end, we analyzed the expression of DNMT1 and DNMT3a along with GAD67 in the brains of the glutamic acid decarboxylase67-enhanced green fluorescent protein (GAD67-GFP) knockin mice. After first confirming that GFP-immunopositive neurons were also GAD67-positive, we showed that in the motor cortex, piriform cortex, striatum, CA1 region of the hippocampus, dentate gyrus, and basolateral amygdala (BLA), GFP immunofluorescence coincided with the signal corresponding to DNMT1 and DNMT3a. A detailed examination of cortical neurons, showed that ≈30% of NeuN-immunopositive neurons were also DNMT1-positive. These data do not exclude the expression of DNMT1 or DNMT3a in glutamatergic neurons and glia. However, they suggest that their expression is low compared with the levels present in GABAergic neurons.
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Affiliation(s)
- Bashkim Kadriu
- Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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87
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Abstract
There are numerous examples of enduring effects of early experience on gene transcription and neural function. We review the emerging evidence for epigenetics as a candidate mechanism for such effects. There is now evidence that intracellular signals activated by environmental events can directly modify the epigenetic state of the genome, including CpG methylation, histone modifications and microRNAs. We suggest that this process reflects an activity-dependent epigenetic plasticity at the level of the genome, comparable with that observed at the synapse. This epigenetic plasticity mediates neuronal differentiation and phenotypic plasticity, including that associated with learning and memory. Altered epigenetic states are also associated with the risk for and expression of mental disorders. In a broader context, these studies define a biological basis for the interplay between environmental signals and the genome in the regulation of individual differences in behavior, cognition and physiology, as well as the risk for psychopathology.
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Affiliation(s)
- Judy Sng
- Integrative Neuroscience Program, Singapore Institute for Clinical Sciences, 30 Medial Drive, Singapore.
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88
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Sanna PP, Repunte-Canonigo V, Guidotti A. Gene profiling of laser-microdissected brain regions and individual cells in drug abuse and schizophrenia research. Methods Mol Biol 2012; 829:541-50. [PMID: 22231837 DOI: 10.1007/978-1-61779-458-2_34] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Application of transcriptomics approaches to accurately dissected anatomically defined brain regions and individual neuronal populations remains a central focus of current neurobiological investigations. A vast selection of methods and commercial products are currently available that allow one to implement routine gene quantitation and profiling from laser-microdissected brain regions, subregions, and neuronal populations. The present chapter reviews laser microdissection strategies for gene expression analyses, strategies for RNA extraction, reverse transcriptase-coupled PCR (RT-PCR), and target preparation for microarray analyses that are in use in our labs.
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Affiliation(s)
- Pietro Paolo Sanna
- Department of Molecular and Integrative Neuroscience, The Scripps Research Institute, La Jolla, CA, USA.
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89
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Kirkbride JB, Susser E, Kundakovic M, Kresovich JK, Davey Smith G, Relton CL. Prenatal nutrition, epigenetics and schizophrenia risk: can we test causal effects? Epigenomics 2012; 4:303-15. [PMID: 22690666 PMCID: PMC3970193 DOI: 10.2217/epi.12.20] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We posit that maternal prenatal nutrition can influence offspring schizophrenia risk via epigenetic effects. In this article, we consider evidence that prenatal nutrition is linked to epigenetic outcomes in offspring and schizophrenia in offspring, and that schizophrenia is associated with epigenetic changes. We focus upon one-carbon metabolism as a mediator of the pathway between perturbed prenatal nutrition and the subsequent risk of schizophrenia. Although post-mortem human studies demonstrate DNA methylation changes in brains of people with schizophrenia, such studies cannot establish causality. We suggest a testable hypothesis that utilizes a novel two-step Mendelian randomization approach, to test the component parts of the proposed causal pathway leading from prenatal nutritional exposure to schizophrenia. Applied here to a specific example, such an approach is applicable for wider use to strengthen causal inference of the mediating role of epigenetic factors linking exposures to health outcomes in population-based studies.
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Affiliation(s)
- James B Kirkbride
- EpiCentre group, Department of Psychiatry, University of Cambridge, Herchel Smith Building for Brain & Mind Sciences, Forvie Site, Robinson Way, Cambridge, UK.
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90
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Abstract
Schizophrenia is a debilitating neurodevelopmental disorder affecting approximately 1% of the population and imposing a significant burden on society. One of the most replicated and well-established postmortem findings is a deficit in the expression of the gene encoding the 67-kDa isoform of glutamic acid decarboxylase (GAD67), the primary GABA-producing enzyme in the brain. GAD67 is expressed in various classes of interneurons, with vastly different morphological, molecular, and physiological properties. Importantly, GABA system deficits in schizophrenia encompass multiple interneuronal subtypes, raising several important questions. First, do different classes of interneurons regulate different aspects of behavior? Second, can we model cell-type-specific GABAergic deficits in mice, and will the rodent findings translate to human physiology? Finally, will this knowledge open the door to knowledge-based approaches to treat schizophrenia?
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Affiliation(s)
- Martin J Schmidt
- Department of Psychiatry, Vanderbilt Kennedy Center, Vanderbilt University, Nashville, Tenn., USA.
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91
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Matrisciano F, Tueting P, Dalal I, Kadriu B, Grayson DR, Davis JM, Nicoletti F, Guidotti A. Epigenetic modifications of GABAergic interneurons are associated with the schizophrenia-like phenotype induced by prenatal stress in mice. Neuropharmacology 2012; 68:184-94. [PMID: 22564440 DOI: 10.1016/j.neuropharm.2012.04.013] [Citation(s) in RCA: 200] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/26/2012] [Accepted: 04/13/2012] [Indexed: 11/18/2022]
Abstract
Human studies suggest that a variety of prenatal stressors are related to high risk for cognitive and behavioral abnormalities associated with psychiatric illness (Markham and Koenig, 2011). Recently, a downregulation in the expression of GABAergic genes (i.e., glutamic acid decarboxylase 67 and reelin) associated with DNA methyltransferase (DNMT) overexpression in GABAergic neurons has been regarded as a characteristic phenotypic component of the neuropathology of psychotic disorders (Guidotti et al., 2011). Here, we characterized mice exposed to prenatal restraint stress (PRS) in order to study neurochemical and behavioral abnormalities related to development of schizophrenia in the adult. Offspring born from non-stressed mothers (control mice) showed high levels of DNMT1 and 3a mRNA expression in the frontal cortex at birth, but these levels progressively decreased at post-natal days (PND) 7, 14, and 60. Offspring born from stressed mothers (PRS mice) showed increased levels of DNMTs compared to controls at all time-points studied including at birth and at PND 60. Using GAD67-GFP transgenic mice, we established that, in both control and PRS mice, high levels of DNMT1 and 3a were preferentially expressed in GABAergic neurons of frontal cortex and hippocampus. Importantly, the overexpression of DNMT in GABAergic neurons was associated with a decrease in reelin and GAD67 expression in PRS mice in early and adult life. PRS mice also showed an increased binding of DNMT1 and MeCP2, and an increase in 5-methylcytosine and 5-hydroxymethylcytosine in specific CpG-rich regions of the reelin and GAD67 promoters. Thus, the epigenetic changes in PRS mice are similar to changes observed in the post-mortem brains of psychiatric patients. Behaviorally, adult PRS mice showed hyperactivity and deficits in social interaction, prepulse inhibition, and fear conditioning that were corrected by administration of valproic acid (a histone deacetylase inhibitor) or clozapine (an atypical antipsychotic with DNA-demethylation activity). Taken together, these data show that prenatal stress in mice induces abnormalities in the DNA methylation network and in behaviors indicative of a schizophrenia-like phenotype. Thus, PRS mice may be a valid model for the investigation of new drugs for schizophrenia treatment targeting DNA methylation. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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MESH Headings
- Animals
- Behavior, Animal/physiology
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/metabolism
- DNA (Cytosine-5-)-Methyltransferase 1
- DNA (Cytosine-5-)-Methyltransferases/genetics
- DNA (Cytosine-5-)-Methyltransferases/metabolism
- Disease Models, Animal
- Extracellular Matrix Proteins/genetics
- Extracellular Matrix Proteins/metabolism
- Female
- Frontal Lobe/metabolism
- GABAergic Neurons/metabolism
- Glutamate Decarboxylase/genetics
- Glutamate Decarboxylase/metabolism
- Hippocampus/metabolism
- Interneurons/metabolism
- Mice
- Motor Activity/genetics
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Phenotype
- Pregnancy
- Prenatal Exposure Delayed Effects/genetics
- Prenatal Exposure Delayed Effects/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reelin Protein
- Restraint, Physical
- Schizophrenia/etiology
- Schizophrenia/genetics
- Schizophrenia/metabolism
- Serine Endopeptidases/genetics
- Serine Endopeptidases/metabolism
- Social Behavior
- Stress, Physiological/physiology
- Stress, Psychological/complications
- Stress, Psychological/genetics
- Stress, Psychological/metabolism
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Affiliation(s)
- Francesco Matrisciano
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, The University of Illinois at Chicago, Chicago, IL 60612, USA.
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92
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Puckett RE, Lubin FD. Epigenetic mechanisms in experience-driven memory formation and behavior. Epigenomics 2012; 3:649-64. [PMID: 22126252 DOI: 10.2217/epi.11.86] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Epigenetic mechanisms have long been associated with the regulation of gene-expression changes accompanying normal neuronal development and cellular differentiation; however, until recently these mechanisms were believed to be statically quiet in the adult brain. Behavioral neuroscientists have now begun to investigate these epigenetic mechanisms as potential regulators of gene-transcription changes in the CNS subserving synaptic plasticity and long-term memory (LTM) formation. Experimental evidence from learning and memory animal models has demonstrated that active chromatin remodeling occurs in terminally differentiated postmitotic neurons, suggesting that these molecular processes are indeed intimately involved in several stages of LTM formation, including consolidation, reconsolidation and extinction. Such chromatin modifications include the phosphorylation, acetylation and methylation of histone proteins and the methylation of associated DNA to subsequently affect transcriptional gene readout triggered by learning. The present article examines how such learning-induced epigenetic changes contribute to LTM formation and influence behavior. In particular, this article is a survey of the specific epigenetic mechanisms that have been demonstrated to regulate gene expression for both transcription factors and growth factors in the CNS, which are critical for LTM formation and storage, as well as how aberrant epigenetic processing can contribute to psychological states such as schizophrenia and drug addiction. Together, the findings highlighted in this article support a novel role for epigenetic mechanisms in the adult CNS serving as potential key molecular regulators of gene-transcription changes necessary for LTM formation and adult behavior.
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Affiliation(s)
- Rosemary E Puckett
- Evelyn F McKnight Brain Institute, Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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93
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94
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Matrisciano F, Tueting P, Maccari S, Nicoletti F, Guidotti A. Pharmacological activation of group-II metabotropic glutamate receptors corrects a schizophrenia-like phenotype induced by prenatal stress in mice. Neuropsychopharmacology 2012; 37:929-38. [PMID: 22089319 PMCID: PMC3280642 DOI: 10.1038/npp.2011.274] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Prenatal exposure to restraint stress causes long-lasting changes in neuroplasticity that likely reflect pathological modifications triggered by early-life stress. We found that the offspring of dams exposed to repeated episodes of restraint stress during pregnancy (here named 'prenatal restraint stress mice' or 'PRS mice') developed a schizophrenia-like phenotype, characterized by a decreased expression of brain-derived neurotrophic factor and glutamic acid decarboxylase 67, an increased expression of type-1 DNA methyl transferase (DNMT1) in the frontal cortex, and a deficit in social interaction, locomotor activity, and prepulse inhibition. PRS mice also showed a marked decrease in metabotropic glutamate 2 (mGlu2) and mGlu3 receptor mRNA and protein levels in the frontal cortex, which was manifested at birth and persisted in adult life. This decrease was associated with an increased binding of DNMT1 to CpG-rich regions of mGlu2 and mGlu3 receptor promoters and an increased binding of MeCP2 to the mGlu2 receptor promoter. Systemic treatment with the selective mGlu2/3 receptor agonist LY379268 (0.5 mg/kg, i.p., twice daily for 5 days), corrected all the biochemical and behavioral abnormalities shown in PRS mice. Our data show for the first time that PRS induces a schizophrenia-like phenotype in mice, and suggest that epigenetic changes in mGlu2 and mGlu3 receptors lie at the core of the pathological programming induced by early-life stress.
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Affiliation(s)
- Francesco Matrisciano
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, The University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Patricia Tueting
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, The University of Illinois at Chicago, Chicago, IL, USA
| | - Stefania Maccari
- Neuroplasticity Team – CNRS UMR 8576/UGSF, North University of Lille1, Lille, France
| | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, University of Rome ‘Sapienza', Rome, Italy,INM Neuromed, Pozzilli, Italy
| | - Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, The University of Illinois at Chicago, Chicago, IL, USA
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95
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Gavin DP, Sharma RP, Chase KA, Matrisciano F, Dong E, Guidotti A. Growth arrest and DNA-damage-inducible, beta (GADD45b)-mediated DNA demethylation in major psychosis. Neuropsychopharmacology 2012; 37:531-42. [PMID: 22048458 PMCID: PMC3242315 DOI: 10.1038/npp.2011.221] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Aberrant neocortical DNA methylation has been suggested to be a pathophysiological contributor to psychotic disorders. Recently, a growth arrest and DNA-damage-inducible, beta (GADD45b) protein-coordinated DNA demethylation pathway, utilizing cytidine deaminases and thymidine glycosylases, has been identified in the brain. We measured expression of several members of this pathway in parietal cortical samples from the Stanley Foundation Neuropathology Consortium (SFNC) cohort. We find an increase in GADD45b mRNA and protein in patients with psychosis. In immunohistochemistry experiments using samples from the Harvard Brain Tissue Resource Center, we report an increased number of GADD45b-stained cells in prefrontal cortical layers II, III, and V in psychotic patients. Brain-derived neurotrophic factor IX (BDNF IXabcd) was selected as a readout gene to determine the effects of GADD45b expression and promoter binding. We find that there is less GADD45b binding to the BDNF IXabcd promoter in psychotic subjects. Further, there is reduced BDNF IXabcd mRNA expression, and an increase in 5-methylcytosine and 5-hydroxymethylcytosine at its promoter. On the basis of these results, we conclude that GADD45b may be increased in psychosis compensatory to its inability to access gene promoter regions.
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Affiliation(s)
- David P Gavin
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Rajiv P Sharma
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, Chicago, IL, USA
| | - Kayla A Chase
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, Chicago, IL, USA
| | - Francesco Matrisciano
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, Chicago, IL, USA
| | - Erbo Dong
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, Chicago, IL, USA
| | - Alessandro Guidotti
- Department of Psychiatry, The Psychiatric Institute, University of Illinois at Chicago, Chicago, IL, USA
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96
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Is DNA methylation responsible for immune system dysfunction in schizophrenia? Med Hypotheses 2011; 77:573-9. [DOI: 10.1016/j.mehy.2011.06.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 01/17/2023]
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97
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Guidotti A, Grayson DR. A neurochemical basis for an epigenetic vision of psychiatric disorders (1994-2009). Pharmacol Res 2011; 64:344-9. [PMID: 21699980 DOI: 10.1016/j.phrs.2011.05.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In 1996, Dr. Costa was invited by Prof. Boris Astrachan, Chairman of the Department of Psychiatry at the University of Illinois at Chicago, to direct the research of the "Psychiatric Institute, Department of Psychiatry, School of Medicine, at the University of Illinois at Chicago." He was asked to develop a seminal research program on psychiatric disorders. Viewed in retrospect, Dr. Costa met and surpassed the challenge, as was usual for him. To elucidate the molecular mechanisms whereby nurture (epigenetic factors) and nature (genetic factors) interact to cause major psychiatric disorders was at the center of Dr. Costa's mission for the last 15 years of his research at the Psychiatric Institute. The challenge for Dr. Costa and his colleagues (Auta, Caruncho, Davis, Grayson, Guidotti, Impagnatiello, Kiedrowski, Larson, Manev, Pappas, Pesold, Pinna, Sharma, Smalheiser, Sugaya, Tueting, Veldic [1-111]) had always been to find new ways to prevent and treat psychiatric disorders with pharmacological agents that failed to have major unwanted side effects. In this list, we have quoted the first authors of the papers pertaining to the field of research highlighted in the title. As you know, Dr. Costa was an eclectic scientist and in his 15 years of studies at UIC, he touched many other aspects of neuroscience research that are not discussed in this overview.
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Affiliation(s)
- Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 Taylor, Chicago, IL 60612, United States.
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98
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Maloku E, Kadriu B, Zhubi A, Dong E, Pibiri F, Satta R, Guidotti A. Selective α4β2 nicotinic acetylcholine receptor agonists target epigenetic mechanisms in cortical GABAergic neurons. Neuropsychopharmacology 2011; 36:1366-74. [PMID: 21368748 PMCID: PMC3096806 DOI: 10.1038/npp.2011.21] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 01/26/2011] [Accepted: 01/28/2011] [Indexed: 12/12/2022]
Abstract
Nicotine improves cognitive performance and attention in both experimental animals and in human subjects, including patients affected by neuropsychiatric disorders. However, the specific molecular mechanisms underlying nicotine-induced behavioral changes remain unclear. We have recently shown in mice that repeated injections of nicotine, which achieve plasma concentrations comparable to those reported in high cigarette smokers, result in an epigenetically induced increase of glutamic acid decarboxylase 67 (GAD(67)) expression. Here we explored the impact of synthetic α(4)β(2) and α(7) nAChR agonists on GABAergic epigenetic parameters. Varenicline (VAR), a high-affinity partial agonist at α(4)β(2) and a lower affinity full agonist at α(7) neuronal nAChR, injected in doses of 1-5 mg/kg/s.c. twice daily for 5 days, elicited a 30-40% decrease of cortical DNA methyltransferase (DNMT)1 mRNA and an increased expression of GAD(67) mRNA and protein. This upregulation of GAD(67) was abolished by the nAChR antagonist mecamylamine. Furthermore, the level of MeCP(2) binding to GAD(67) promoters was significantly reduced following VAR administration. This effect was abolished when VAR was administered with mecamylamine. Similar effects on cortical DNMT1 and GAD(67) expression were obtained after administration of A-85380, an agonist that binds to α(4)β(2) but has negligible affinity for α(3)β(4) or α(7) subtypes containing nAChR. In contrast, PNU-282987, an agonist of the homomeric α(7) nAChR, failed to decrease cortical DNMT1 mRNA or to induce GAD(67) expression. The present study suggests that the α(4)β(2) nAChR agonists may be better suited to control the epigenetic alterations of GABAergic neurons in schizophrenia than the α(7) nAChR agonists.
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Affiliation(s)
- Ekrem Maloku
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Bashkim Kadriu
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Adrian Zhubi
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Erbo Dong
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Fabio Pibiri
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Rosalba Satta
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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99
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Pidsley R, Mill J. Epigenetic studies of psychosis: current findings, methodological approaches, and implications for postmortem research. Biol Psychiatry 2011; 69:146-56. [PMID: 20510393 DOI: 10.1016/j.biopsych.2010.03.029] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/24/2010] [Accepted: 03/25/2010] [Indexed: 12/22/2022]
Abstract
It has been widely speculated that epigenetic changes may play a role in the etiology of psychotic illnesses such as schizophrenia and bipolar disorder. Epigenetics is the study of mitotically heritable, but reversible, changes in gene expression that occur without a change in the genomic DNA sequence, brought about principally through alterations in DNA methylation and chromatin structure. Although numerous studies have examined psychosis-associated gene expression changes in postmortem brain samples, epigenetic studies of psychosis are in their infancy. In this article, we discuss methodologic and logistic issues related to epigenomic studies using postmortem brain tissue, before discussing the future implications of such research for our understanding of psychosis.
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Affiliation(s)
- Ruth Pidsley
- Institute of Psychiatry, King's College London, United Kingdom
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100
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Horváth S, Janka Z, Mirnics K. Analyzing schizophrenia by DNA microarrays. Biol Psychiatry 2011; 69:157-62. [PMID: 20801428 PMCID: PMC2994975 DOI: 10.1016/j.biopsych.2010.07.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/12/2010] [Accepted: 07/14/2010] [Indexed: 01/20/2023]
Abstract
To understand the pathological processes of schizophrenia, we must embrace the analysis of the diseased human brain: we will never be able to recapitulate the pathology of uniquely human disorders in an animal model. Based on the outcome of the transcriptome profiling experiments performed to date, it appears that schizophrenia is associated with a global gene expression disturbance across many cortical regions. In addition, transcriptome changes are present in multiple cell types, including specific subclasses of principal neurons, interneurons, and oligodendrocytes. Furthermore, transcripts related to synaptic transmission, energy metabolism, and inhibitory neurotransmission are routinely found underexpressed in the postmortem brain tissue of subjects with schizophrenia. To put these transcriptome data in biological context, we must make our data publicly available and report our findings in a proper, expanded Minimum Information About a Microarray Experiment format. Cell-type specific expression profiling and sequencing-based transcript assessments should be expanded, with particular attention to understanding splice-variant changes in various mental disorders. Deciphering the pathophysiology of mental disorders depends on integrating data from across many research fields and techniques. Leads from postmortem transcriptome profiling will be essential to generate model animals, perform tissue culture experiments, and develop or evaluate novel drugs to treat this devastating disorder.
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Affiliation(s)
- Szatmár Horváth
- Department of Psychiatry, Vanderbilt University, Nashville, TN 37232, USA,Department of Psychiatry, University of Szeged, 6725 Szeged, Hungary
| | - Zoltán Janka
- Department of Psychiatry, University of Szeged, 6725 Szeged, Hungary
| | - Károly Mirnics
- Department of Psychiatry, Vanderbilt University, Nashville, TN 37232, USA,Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232, USA,Correspondence: Karoly Mirnics, Department of Psychiatry, Vanderbilt University, 8130A MRB III, 465 21st Avenue South, Nashville TN 37232, USA, , Office phone: 615-936-1074, http://mirnicslab.vanderbilt.edu/mirnicslab/
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