1
|
Murphy MD, Heller EA. Convergent actions of stress and stimulants via epigenetic regulation of neural circuitry. Trends Neurosci 2022; 45:955-967. [PMID: 36280459 PMCID: PMC9671852 DOI: 10.1016/j.tins.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/21/2022] [Accepted: 10/01/2022] [Indexed: 11/17/2022]
Abstract
The dorsal striatum integrates prior and current information to guide appropriate decision-making. Chronic stress and stimulant exposure interferes with decision-making, and can confer similar cognitive and behavioral inflexibilities. This review examines the literature on acute and chronic regulation of the epigenome by stress and stimulants. Recent evidence suggests that exposures to stress and stimulants share similarities in the manners in which they regulate the dorsal striatum epigenome through DNA methylation, transposable element activity, and histone post-translational modifications. These findings suggest that chronic stress and stimulant exposure leads to the accumulation of epigenetic modifications that impair immediate and future neuron function and activity. Such epigenetic mechanisms represent potential therapeutic targets for ameliorating convergent symptoms of stress and addiction.
Collapse
Affiliation(s)
- Michael D Murphy
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA, 19104, USA; Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Elizabeth A Heller
- Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| |
Collapse
|
2
|
Veerappa A, Pendyala G, Guda C. A systems omics-based approach to decode substance use disorders and neuroadaptations. Neurosci Biobehav Rev 2021; 130:61-80. [PMID: 34411560 PMCID: PMC8511293 DOI: 10.1016/j.neubiorev.2021.08.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/23/2021] [Accepted: 08/14/2021] [Indexed: 11/15/2022]
Abstract
Substance use disorders (SUDs) are a group of neuropsychiatric conditions manifesting due to excessive dependence on potential drugs of abuse such as psychostimulants, opioids including prescription opioids, alcohol, inhalants, etc. Experimental studies have generated enormous data in the area of SUDs, but outcomes from such data have remained largely fragmented. In this review, we attempt to coalesce these data points providing an important first step towards our understanding of the etiology of SUDs. We propose and describe a 'core addictome' pathway that behaves central to all SUDs. Besides, we also have made some notable observations paving way for several hypotheses; MECP2 behaves as a master switch during substance use; five distinct gene clusters were identified based on respective substance addiction; a central cluster of genes serves as a hub of the addiction pathway connecting all other substance addiction clusters. In addition to describing these findings, we have emphasized the importance of some candidate genes that are of substantial interest for further investigation and serve as high-value targets for translational efforts.
Collapse
Affiliation(s)
- Avinash Veerappa
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Gurudutt Pendyala
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA; Department of Anesthesiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA; Child Health Research Institute, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Chittibabu Guda
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, USA; Center for Biomedical Informatics Research and Innovation, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
| |
Collapse
|
3
|
López AJ, Siciliano CA, Calipari ES. Activity-Dependent Epigenetic Remodeling in Cocaine Use Disorder. Handb Exp Pharmacol 2019; 258:231-263. [PMID: 31628597 DOI: 10.1007/164_2019_257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Substance use disorder (SUD) is a behavioral disorder characterized by cycles of abstinence, drug seeking, and relapse. SUD is characterized by aberrant learning processes which develop after repeated exposure to drugs of abuse. At the core of this phenotype is the persistence of symptoms, such as craving and relapse to drug seeking, long after the cessation of drug use. The neural basis of these behavioral changes has been linked to dysfunction in neural circuits across the brain; however, the molecular drivers that allow for these changes to persist beyond the lifespan of any individual protein remain opaque. Epigenetic adaptations - where DNA is modified to increase or decrease the probability of gene expression at key genes - have been identified as a mechanism underlying the long-lasting nature of drug-seeking behavior. Thus, to understand SUD, it is critical to define the interplay between neuronal activation and longer-term changes in transcription and epigenetic remodeling and define their role in addictive behaviors. In this review, we discuss the current understanding of drug-induced changes to circuit function, recent discoveries in epigenetic mechanisms that mediate these changes, and, ultimately, how these adaptations drive the persistent nature of relapse, with emphasis on adaptations in models of cocaine use disorder. Understanding the complex interplay between epigenetic gene regulation and circuit activity will be critical in elucidating the neural mechanisms underlying SUD. This, with the advent of novel genetic-based techniques, will allow for the generation of novel therapeutic avenues to improve treatment outcomes in SUD.
Collapse
Affiliation(s)
- Alberto J López
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.,Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Cody A Siciliano
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.,Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Erin S Calipari
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA. .,Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA. .,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA. .,Department of Molecular Physiology and Biophysics, Vanderbilt Institute for Infection, Immunology, and Infection, Vanderbilt University School of Medicine, Nashville, TN, USA. .,Department of Psychiatry and Behavioral Sciences, Vanderbilt Institute for Infection, Immunology, and Infection, Vanderbilt University School of Medicine, Nashville, TN, USA.
| |
Collapse
|
4
|
Cotto B, Li H, Tuma RF, Ward SJ, Langford D. Cocaine-mediated activation of microglia and microglial MeCP2 and BDNF production. Neurobiol Dis 2018; 117:28-41. [PMID: 29859319 PMCID: PMC6051925 DOI: 10.1016/j.nbd.2018.05.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 05/09/2018] [Accepted: 05/29/2018] [Indexed: 12/17/2022] Open
Abstract
The molecular substrates underlying cocaine reinforcement and addiction have been studied for decades, with a primary focus on signaling molecules involved in modulation of neuronal communication. Brain-derived neurotrophic factor (BDNF) is an important signaling molecule involved in neuronal dendrite and spine modulation. Methyl CpG binding protein 2 (MeCP2) binds to the promoter region of BDNF to negatively regulate its expression and cocaine can recruit MeCP2 to alter the expression of genes such as BDNF that are involved in synaptic plasticity. For several decades, BDNF has been implicated in mediating synaptic plasticity associated with cocaine abuse, and most studies report that neurons are the primary source for BDNF production in the brain. The current study assessed the effects of intravenous cocaine self-administration on microglial activation, and MeCP2 and BDNF expression in reward regions of the brain in vivo, as well as determined specific effects of cocaine exposure on MeCP2 and BDNF expression in human primary neurons and microglia. The results from this study highlight a distinct molecular pathway in microglia through which cocaine increases BDNF, including the phosphorylation of MeCP2 its subsequent translocation from the nucleus to the cytosol, which frees the BDNF promoter and permits its transcriptional activation. Results from these studies show for the first time that cocaine self-administration increases microglial activation, and that microglial MeCP2 is a sensitive target of cocaine resulting in increased release of BDNF from microglia, and possibly contributing to cocaine-induced synaptic plasticity.
Collapse
Affiliation(s)
- Bianca Cotto
- Department of Neuroscience, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Hongbo Li
- Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Ronald F Tuma
- Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Sara Jane Ward
- Department of Pharmacology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Dianne Langford
- Department of Neuroscience, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA.
| |
Collapse
|
5
|
Kumar R, Jain V, Kushwah N, Dheer A, Mishra KP, Prasad D, Singh SB. Role of DNA Methylation in Hypobaric Hypoxia-Induced Neurodegeneration and Spatial Memory Impairment. Ann Neurosci 2018; 25:191-200. [PMID: 31000957 DOI: 10.1159/000490368] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/24/2018] [Indexed: 12/19/2022] Open
Abstract
Hypobaric hypoxia (HH) is a major stress factor that is associated with physiological, biochemical, molecular and genomic alterations. Brain is the organ that reacts sensitively to oxygen deprivation, which leads to oxidative stress and cognitive function impairment. Our previous studies have reported that downregulation of brain derived neurotrophic factor (BDNF) leads to neurodegeneration and memory impairment. The aim of the present study was to investigate the effect of HH exposure on DNA methylation and its regulation in BDNF expression, neurodegeneration and spatial memory impairment. For this purpose, Sprague Dawley rats were exposed to HH at a simulated altitude of 25,000 feet for 14 days. Real-time polymerase chain reaction was used for transcriptional expression of DNA Methyltransferases (DNMTs) including DNMT1, DNMT3a and -DNMT3b, and immunoblotting was used for the translational expression of DNMT1, DNMT3a, DNMT3b, Methyl CpG binding protein 2 (MeCP2), pMeCP2 and BDNF in rat hippocampus. Additionally, neuronal morphology alteration and neurodegeneration in CA1 region of hippocampus were investigated though Cresyl violet (CV) staining and Fluoro-Jade C staining respectively. Results obtained suggested that HH exposure increased the expression of DNMT1 DNMT3b at the mRNA as well as protein level, whereas no significant change was observed in the level of DNMT3a. Furthermore, the level of pMeCP2 and BDNF were significantly decreased; however, the expression level of MeCP2 was significantly increased. The CV and Fluoro-Jade C-positive cells were significantly enhanced in the CA1 region of hippocampus in the HH exposed group as compared to unexposed rats. Thus, the present study concluded that HH decreases neuronal activation by the upregulation of DNA methylation and MeCP2 and decreased the expression of pMeCP2, which result in the downregulation of BDNF. The decreased BDNF expression is associated with neuronal loss and spatial memory impairment. This study highlights that DNMT inhibition could be an important therapeutic target for neurodegenerative diseases.
Collapse
Affiliation(s)
- Rahul Kumar
- Neurobiology Division, Defence Institute of Physiology and Allied Science (DIAPS), DRDO, New Delhi, India
| | - Vishal Jain
- Neurophysiology Division, Defence Institute of Physiology and Allied Science (DIAPS), DRDO, New Delhi, India
| | - Neetu Kushwah
- Neurobiology Division, Defence Institute of Physiology and Allied Science (DIAPS), DRDO, New Delhi, India
| | - Aastha Dheer
- Neurobiology Division, Defence Institute of Physiology and Allied Science (DIAPS), DRDO, New Delhi, India
| | - Kamla Prasad Mishra
- Directorate General Life Sciences, Defence research Development Organisation (DRDO), Government of India, DRDO Bhawan, Rajaji Marg, New Delhi, India
| | - Dipti Prasad
- Neurobiology Division, Defence Institute of Physiology and Allied Science (DIAPS), DRDO, New Delhi, India
| | - Shashi Bala Singh
- Directorate General Life Sciences, Defence research Development Organisation (DRDO), Government of India, DRDO Bhawan, Rajaji Marg, New Delhi, India
| |
Collapse
|
6
|
Vaillancourt K, Ernst C, Mash D, Turecki G. DNA Methylation Dynamics and Cocaine in the Brain: Progress and Prospects. Genes (Basel) 2017; 8:genes8050138. [PMID: 28498318 PMCID: PMC5448012 DOI: 10.3390/genes8050138] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/04/2017] [Indexed: 12/27/2022] Open
Abstract
Cytosine modifications, including DNA methylation, are stable epigenetic marks that may translate environmental change into transcriptional regulation. Research has begun to investigate DNA methylation dynamics in relation to cocaine use disorders. Specifically, DNA methylation machinery, including methyltransferases and binding proteins, are dysregulated in brain reward pathways after chronic cocaine exposure. In addition, numerous methylome-wide and candidate promoter studies have identified differential methylation, at the nucleotide level, in rodent models of cocaine abuse and drug seeking behavior. This review highlights the current progress in the field of cocaine-related methylation, and offers considerations for future research.
Collapse
Affiliation(s)
- Kathryn Vaillancourt
- Department of Psychiatry, McGill Group for Suicide Studies, Douglas Mental Health University Institute, McGill University, Verdun, QC H4H 1R3, Canada.
| | - Carl Ernst
- Department of Psychiatry, McGill Group for Suicide Studies, Douglas Mental Health University Institute, McGill University, Verdun, QC H4H 1R3, Canada.
| | - Deborah Mash
- Department of Neurology, University of Miami Miller School of Medicine, University of Miami, Coral Gables, FL 33146, USA.
| | - Gustavo Turecki
- Department of Psychiatry, McGill Group for Suicide Studies, Douglas Mental Health University Institute, McGill University, Verdun, QC H4H 1R3, Canada.
| |
Collapse
|
7
|
Ausió J. MeCP2 and the enigmatic organization of brain chromatin. Implications for depression and cocaine addiction. Clin Epigenetics 2016; 8:58. [PMID: 27213019 PMCID: PMC4875624 DOI: 10.1186/s13148-016-0214-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/20/2016] [Indexed: 12/21/2022] Open
Abstract
Methyl CpG binding protein 2 (MeCP2) is a highly abundant chromosomal protein within the brain. It is hence not surprising that perturbations in its genome-wide distribution, and at particular loci within this tissue, can result in widespread neurological disorders that transcend the early implications of this protein in Rett syndrome (RTT). Yet, the details of its role and involvement in chromatin organization are still poorly understood. This paper focuses on what is known to date about all of this with special emphasis on the relation to different epigenetic modifications (DNA methylation, histone acetylation/ubiquitination, MeCP2 phosphorylation and miRNA). We showcase all of the above in two particular important neurological functional alterations in the brain: depression (major depressive disorder [MDD]) and cocaine addiction, both of which affect the MeCP2 homeostasis and result in significant changes in the overall levels of these epigenetic marks.
Collapse
Affiliation(s)
- Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6 Canada
| |
Collapse
|
8
|
Cadet JL. Epigenetics of Stress, Addiction, and Resilience: Therapeutic Implications. Mol Neurobiol 2016; 53:545-560. [PMID: 25502297 PMCID: PMC4703633 DOI: 10.1007/s12035-014-9040-y] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/30/2014] [Indexed: 12/12/2022]
Abstract
Substance use disorders (SUDs) are highly prevalent. SUDs involve vicious cycles of binges followed by occasional periods of abstinence with recurrent relapses despite treatment and adverse medical and psychosocial consequences. There is convincing evidence that early and adult stressful life events are risks factors for the development of addiction and serve as cues that trigger relapses. Nevertheless, the fact that not all individuals who face traumatic events develop addiction to licit or illicit drugs suggests the existence of individual and/or familial resilient factors that protect these mentally healthy individuals. Here, I give a brief overview of the epigenetic bases of responses to stressful events and of epigenetic changes associated with the administration of drugs of abuse. I also discuss the psychobiology of resilience and alterations in epigenetic markers that have been observed in models of resilience. Finally, I suggest the possibility that treatment of addiction should involve cognitive and pharmacological approaches that enhance resilience in at risk individuals. Similar approaches should also be used with patients who have already succumbed to the nefarious effects of addictive substances.
Collapse
Affiliation(s)
- Jean Lud Cadet
- Molecular Neuropsychiatry Research Branch, DHHS/NIH/NIDA Intramural Research Program, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA.
| |
Collapse
|
9
|
Zimmermann CA, Hoffmann A, Raabe F, Spengler D. Role of mecp2 in experience-dependent epigenetic programming. Genes (Basel) 2015; 6:60-86. [PMID: 25756305 PMCID: PMC4377834 DOI: 10.3390/genes6010060] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/18/2015] [Accepted: 02/28/2015] [Indexed: 12/28/2022] Open
Abstract
Mutations in the X-linked gene MECP2, the founding member of a family of proteins recognizing and binding to methylated DNA, are the genetic cause of a devastating neurodevelopmental disorder in humans, called Rett syndrome. Available evidence suggests that MECP2 protein has a critical role in activity-dependent neuronal plasticity and transcription during brain development. Moreover, recent studies in mice show that various posttranslational modifications, notably phosphorylation, regulate Mecp2’s functions in learning and memory, drug addiction, depression-like behavior, and the response to antidepressant treatment. The hypothalamic-pituitary-adrenal (HPA) axis drives the stress response and its deregulation increases the risk for a variety of mental disorders. Early-life stress (ELS) typically results in sustained HPA-axis deregulation and is a major risk factor for stress related diseases, in particular major depression. Interestingly, Mecp2 protein has been shown to contribute to ELS-dependent epigenetic programming of Crh, Avp, and Pomc, all of these genes enhance HPA-axis activity. Hereby ELS regulates Mecp2 phosphorylation, DNA binding, and transcriptional activities in a tissue-specific and temporospatial manner. Overall, these findings suggest MECP2 proteins are so far underestimated and have a more dynamic role in the mediation of the gene-environment dialog and epigenetic programming of the neuroendocrine stress system in health and disease.
Collapse
Affiliation(s)
- Christoph A Zimmermann
- Max Planck Institute of Psychiatry, Translational Research, Kraepelinstr. 2-10, Munich 80804, Germany.
| | - Anke Hoffmann
- Max Planck Institute of Psychiatry, Translational Research, Kraepelinstr. 2-10, Munich 80804, Germany.
| | - Florian Raabe
- Max Planck Institute of Psychiatry, Translational Research, Kraepelinstr. 2-10, Munich 80804, Germany.
| | - Dietmar Spengler
- Max Planck Institute of Psychiatry, Translational Research, Kraepelinstr. 2-10, Munich 80804, Germany.
| |
Collapse
|
10
|
Li H, Chang Q. Regulation and function of stimulus-induced phosphorylation of MeCP2. FRONTIERS IN BIOLOGY 2014; 9:367-375. [PMID: 25568644 PMCID: PMC4283599 DOI: 10.1007/s11515-014-1330-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
DNA methylation-dependent epigenetic regulation plays important roles in the development and function of the mammalian nervous system. MeCP2 is a key player in recognizing methylated DNA and interpreting the epigenetic information encoded in different DNA methylation patterns. Mutations in the MECP2 gene cause Rett syndrome, a devastating neurological disease that shares many features with autism. One interesting aspect of MeCP2 function is that it can be phosphorylated in response to diverse stimuli. Insights into the regulation and function of MeCP2 phosphorylation will help improve our understanding of how MeCP2 integrates environmental stimuli in neuronal nuclei to generate adaptive responses and may eventually lead to treatments for patients.
Collapse
Affiliation(s)
- Hongda Li
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
- Genetics Training Program, University of Wisconsin-Madison, Madison, WI 53705,USA
| | - Qiang Chang
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
- Genetics Training Program, University of Wisconsin-Madison, Madison, WI 53705,USA
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53705, USA
| |
Collapse
|
11
|
Bellini E, Pavesi G, Barbiero I, Bergo A, Chandola C, Nawaz MS, Rusconi L, Stefanelli G, Strollo M, Valente MM, Kilstrup-Nielsen C, Landsberger N. MeCP2 post-translational modifications: a mechanism to control its involvement in synaptic plasticity and homeostasis? Front Cell Neurosci 2014; 8:236. [PMID: 25165434 PMCID: PMC4131190 DOI: 10.3389/fncel.2014.00236] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/27/2014] [Indexed: 12/02/2022] Open
Abstract
Although Rett syndrome (RTT) represents one of the most frequent forms of severe intellectual disability in females worldwide, we still have an inadequate knowledge of the many roles played by MeCP2 (whose mutations are responsible for most cases of RTT) and their relevance for RTT pathobiology. Several studies support a role of MeCP2 in the regulation of synaptic plasticity and homeostasis. At the molecular level, MeCP2 is described as a repressor capable of inhibiting gene transcription through chromatin compaction. Indeed, it interacts with several chromatin remodeling factors, such as HDAC-containing complexes and ATRX. Other studies have inferred that MeCP2 functions also as an activator; a role in regulating mRNA splicing and in modulating protein synthesis has also been proposed. Further, MeCP2 avidly binds both 5-methyl- and 5-hydroxymethyl-cytosine. Recent evidence suggests that it is the highly disorganized structure of MeCP2, together with its post-translational modifications (PTMs) that generate and regulate this functional versatility. Indeed, several reports have demonstrated that differential phosphorylation of MeCP2 is a key mechanism by which the methyl binding protein modulates its affinity for its partners, gene expression and cellular adaptations to stimuli and neuronal plasticity. As logic consequence, generation of phospho-defective Mecp2 knock-in mice has permitted associating alterations in neuronal morphology, circuit formation, and mouse behavioral phenotypes with specific phosphorylation events. MeCP2 undergoes various other PTMs, including acetylation, ubiquitination and sumoylation, whose functional roles remain largely unexplored. These results, together with the genome-wide distribution of MeCP2 and its capability to substitute histone H1, recall the complex regulation of histones and suggest the relevance of quickly gaining a deeper comprehension of MeCP2 PTMs, the respective writers and readers and the consequent functional outcomes.
Collapse
Affiliation(s)
- Elisa Bellini
- Division of Neuroscience, San Raffaele Rett Research Center, San Raffaele Scientific Institute Milan, Italy
| | - Giulio Pavesi
- Department of Biosciences, University of Milan Milan, Italy
| | - Isabella Barbiero
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Anna Bergo
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Chetan Chandola
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Mohammad S Nawaz
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Laura Rusconi
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Gilda Stefanelli
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Marta Strollo
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Maria M Valente
- Division of Neuroscience, San Raffaele Rett Research Center, San Raffaele Scientific Institute Milan, Italy
| | - Charlotte Kilstrup-Nielsen
- Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| | - Nicoletta Landsberger
- Division of Neuroscience, San Raffaele Rett Research Center, San Raffaele Scientific Institute Milan, Italy ; Section of Biomedical Research, Laboratory of Genetic and Epigenetic Control of Gene Expression, Department of Theoretic and Applied Sciences, University of Insubria Busto Arsizio, Italy
| |
Collapse
|
12
|
Abstract
Rett syndrome (RTT) is a severe and progressive neurological disorder, which mainly affects young females. Mutations of the methyl-CpG binding protein 2 (MECP2) gene are the most prevalent cause of classical RTT cases. MECP2 mutations or altered expression are also associated with a spectrum of neurodevelopmental disorders such as autism spectrum disorders with recent links to fetal alcohol spectrum disorders. Collectively, MeCP2 relation to these neurodevelopmental disorders highlights the importance of understanding the molecular mechanisms by which MeCP2 impacts brain development, mental conditions, and compromised brain function. Since MECP2 mutations were discovered to be the primary cause of RTT, a significant progress has been made in the MeCP2 research, with respect to the expression, function and regulation of MeCP2 in the brain and its contribution in RTT pathogenesis. To date, there have been intensive efforts in designing effective therapeutic strategies for RTT benefiting from mouse models and cells collected from RTT patients. Despite significant progress in MeCP2 research over the last few decades, there is still a knowledge gap between the in vitro and in vivo research findings and translating these findings into effective therapeutic interventions in human RTT patients. In this review, we will provide a synopsis of Rett syndrome as a severe neurological disorder and will discuss the role of MeCP2 in RTT pathophysiology.
Collapse
|
13
|
Nielsen DA, Utrankar A, Reyes JA, Simons DD, Kosten TR. Epigenetics of drug abuse: predisposition or response. Pharmacogenomics 2013; 13:1149-60. [PMID: 22909205 DOI: 10.2217/pgs.12.94] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Drug addiction continues to be a serious medical and social problem. Vulnerability to develop an addiction to drugs is dependent on genetic, environmental, social and biological factors. In particular, the interactions of environmental and genetic factors indicate the significance of epigenetic mechanisms, which have been found to occur in response to illicit drug use or as underlying factors in chronic substance abuse and relapse. Epigenetics is defined as the heritable and possibly reversible modifications in gene expression that do not involve alterations in the DNA sequence. This review discusses the various types of epigenetic modifications and their relevance to drug addiction to elucidate whether epigenetics is a predisposing factor, or a response to, developing an addiction to drugs of abuse.
Collapse
Affiliation(s)
- David A Nielsen
- Menninger Department of Psychiatry & Behavioral Sciences, Baylor College of Medicine & the Michael E DeBakey VA Medical Center, 2002 Holcombe Boulevard, Houston, TX 77030, USA.
| | | | | | | | | |
Collapse
|
14
|
Ciccarelli A, Calza A, Santoru F, Grasso F, Concas A, Sassoè-Pognetto M, Giustetto M. Morphine withdrawal produces ERK-dependent and ERK-independent epigenetic marks in neurons of the nucleus accumbens and lateral septum. Neuropharmacology 2013; 70:168-79. [PMID: 23347952 DOI: 10.1016/j.neuropharm.2012.12.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/30/2012] [Accepted: 12/14/2012] [Indexed: 01/29/2023]
Abstract
Epigenetic changes such as covalent modifications of histone proteins represent complex molecular signatures that provide a cellular memory of previously experienced stimuli without irreversible changes of the genetic code. In this study we show that new gene expression induced in vivo by morphine withdrawal occurs with concomitant epigenetic modifications in brain regions critically involved in drug-dependent behaviors. We found that naloxone-precipitated withdrawal, but not chronic morphine administration, caused a strong induction of phospho-histone H3 immunoreactivity in the nucleus accumbens (NAc) shell/core and in the lateral septum (LS), a change that was accompanied by augmented H3 acetylation (lys14) in neurons of the NAc shell. Morphine withdrawal induced the phosphorylation of the epigenetic factor methyl-CpG-binding protein 2 (MeCP2) in Ser421 both in the LS and the NAc shell. These epigenetic changes were accompanied by the activation of members of the ERK pathway as well as increased expression of the immediate early genes (IEG) c-fos and activity-regulated cytoskeleton-associated protein (Arc/Arg3.1). Using a pharmacological approach, we found that H3 phosphorylation and IEG expression were partially dependent on ERK activation, while MeCP2 phosphorylation was fully ERK-independent. These findings provide new important information on the role of the ERK pathway in the regulation of epigenetic marks and gene expression that may concur to regulate in vivo the cellular changes underlying the onset of the opioid withdrawal syndrome.
Collapse
Affiliation(s)
- Alessandro Ciccarelli
- University of Turin, Department of Neuroscience, C.so M. D'Azeglio 52, 10126 Turin, Italy
| | | | | | | | | | | | | |
Collapse
|
15
|
McCarthy DM, Brown AN, Bhide PG. Regulation of BDNF expression by cocaine. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2012; 85:437-46. [PMID: 23239946 PMCID: PMC3516887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors. It is expressed throughout the nervous system. A unique feature of the BDNF gene is the existence of multiple mRNA transcripts, all of which are translated into BDNF protein, suggesting a multilevel regulation of expression. In particular, the BDNF exon IV promoter region is a preferential target for epigenetic alterations, as it contains binding sites for CREB and MeCP2, two transcriptional regulators known to mediate epigenetic changes. Exposure to drugs of abuse is known to modulate epigenetic regulation of BDNF gene expression. This review will discuss how exposure to cocaine, one of the most addictive drugs known to mankind, can produce alterations in BDNF gene expression, especially in the mesolimbic dopaminergic system, which lead to alterations in the reward-mediated behaviors involved in addiction.
Collapse
Affiliation(s)
- Deirdre M. McCarthy
- To whom all correspondence should be
addressed: Deirdre M. McCarthy, Department of Biomedical Sciences, Florida State
University College of Medicine, 1115 West Call St., Tallahassee, FL 32306; Tele:
850-645-0263; Fax: 850-644-5781;
| | | | | |
Collapse
|
16
|
Abstract
MeCP2 (methyl CpG binding protein 2) is a key player in recognizing methylated DNA and interpreting the epigenetic information encoded in different DNA methylation patterns. The functional significance of MeCP2 to the mammalian nervous system is highlighted by the discovery that mutations in the MECP2 gene cause Rett syndrome (RTT), a devastating neurological disease that shares many features with autism. Synaptic scaling is a form of non-Hebbian homeostatic plasticity that allows neurons to regulate overall excitability in response to changes in network neuronal activity levels. While it is known that neuronal activity can induce phosphorylation of MeCP2 and that MeCP2 can regulate synaptic scaling, the molecular link between MeCP2 phosphorylation and synaptic scaling remains undefined. We show here that MeCP2 phosphorylation is specifically required for bicuculline-induced synaptic scaling down in mouse hippocampal neurons and this phenotype is mediated by mGluR5 (metabotropic glutamate receptor 5). Our results reveal an important function of MeCP2 in regulating neuronal homeostasis and may eventually help us understand how MECP2 mutations cause RTT.
Collapse
|
17
|
Archer T, Oscar-Berman M, Blum K, Gold M. Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry. ACTA ACUST UNITED AC 2012; 3:1000115. [PMID: 23264884 DOI: 10.4172/2157-7412.1000115] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions.
Collapse
Affiliation(s)
- Trevor Archer
- Department of Psychology, University of Gothenburg, Box 500, SE-40530 Gothenburg, Sweden
| | | | | | | |
Collapse
|