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Lockman S, Genung M, Sheikholeslami K, Sher AA, Kroft D, Buist M, Olson CO, Toor B, Rastegar M. Transcriptional Inhibition of the Mecp2 Promoter by MeCP2E1 and MeCP2E2 Isoforms Suggests Negative Auto-Regulatory Feedback that can be Moderated by Metformin. J Mol Neurosci 2024; 74:14. [PMID: 38277073 DOI: 10.1007/s12031-023-02177-0] [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: 08/31/2023] [Accepted: 12/29/2023] [Indexed: 01/27/2024]
Abstract
The epigenetic factor Methyl-CpG-Binding Protein 2 (MeCP2) is a nuclear protein that binds methylated DNA molecules (both 5-methylcytosine and 5-hydroxymethylcytosine) and controls gene transcription. MeCP2 is an important transcription factor that acts in a dose-dependent manner in the brain; thus, its optimal expression level in brain cells is important. As such, its deregulated expression, as well as gain- or loss-of-function mutation, lead to impaired neurodevelopment, and compromised structure and function of brain cells, particularly in neurons. Studies from others and us have characterized two well-recognized MeCP2 isoforms: MeCP2E1 and MeCP2E2. We have reported that in Daoy medulloblastoma brain cells, MeCP2E2 overexpression leads to MeCP2E1 protein degradation. Whether MeCP2 isoforms regulate the Mecp2 promoter regulatory elements remains unexplored. We previously showed that in Daoy cells, metformin (an anti-diabetic drug) induces MECP2E1 transcripts. However, possible impact of metformin on the Mecp2 promoter activity was not studied. Here, we generated stably transduced Daoy cell reporters to express EGFP driven by the Mecp2 promoter. Transduced cells were sorted into four EGFP-expressing groups (R4-to-R7) with different intensities of EGFP expression. Our results confirm that the Mecp2 promoter is active in Daoy cells, and that overexpression of either isoform inhibits the Mecp2 promoter activity, as detected by flow cytometry and luciferase reporter assays. Interestingly, metformin partially relieved the inhibitory effect of MeCP2E1 on the Mecp2 promoter, detected by flow cytometry. Taken together, our data provide important insight towards the regulation of MeCP2 isoforms at the promoter level, which might have biological relevance to the neurobiology of the brain.
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Affiliation(s)
- Sandhini Lockman
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Matthew Genung
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Kimia Sheikholeslami
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Annan Ali Sher
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Daniel Kroft
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Marjorie Buist
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Carl O Olson
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Brian Toor
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.
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Nejati-Koshki K, Roberts CT, Babaei G, Rastegar M. The Epigenetic Reader Methyl-CpG-Binding Protein 2 (MeCP2) Is an Emerging Oncogene in Cancer Biology. Cancers (Basel) 2023; 15:2683. [PMID: 37345019 PMCID: PMC10216337 DOI: 10.3390/cancers15102683] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 06/23/2023] Open
Abstract
Epigenetic mechanisms are gene regulatory processes that control gene expression and cellular identity. Epigenetic factors include the "writers", "readers", and "erasers" of epigenetic modifications such as DNA methylation. Accordingly, the nuclear protein Methyl-CpG-Binding Protein 2 (MeCP2) is a reader of DNA methylation with key roles in cellular identity and function. Research studies have linked altered DNA methylation, deregulation of MeCP2 levels, or MECP2 gene mutations to different types of human disease. Due to the high expression level of MeCP2 in the brain, many studies have focused on its role in neurological and neurodevelopmental disorders. However, it is becoming increasingly apparent that MeCP2 also participates in the tumorigenesis of different types of human cancer, with potential oncogenic properties. It is well documented that aberrant epigenetic regulation such as altered DNA methylation may lead to cancer and the process of tumorigenesis. However, direct involvement of MeCP2 with that of human cancer was not fully investigated until lately. In recent years, a multitude of research studies from independent groups have explored the molecular mechanisms involving MeCP2 in a vast array of human cancers that focus on the oncogenic characteristics of MeCP2. Here, we provide an overview of the proposed role of MeCP2 as an emerging oncogene in different types of human cancer.
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Affiliation(s)
- Kazem Nejati-Koshki
- Pharmaceutical Sciences Research Center, Ardabil University of Medical Sciences, Ardabil 85991-56189, Iran;
| | - Chris-Tiann Roberts
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada;
| | - Ghader Babaei
- Department of Clinical Biochemistry, Faculty of Medicine, Urmia University of Medical Sciences, Urmia 57157-89400, Iran;
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada;
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MeCP2 Is an Epigenetic Factor That Links DNA Methylation with Brain Metabolism. Int J Mol Sci 2023; 24:ijms24044218. [PMID: 36835623 PMCID: PMC9966807 DOI: 10.3390/ijms24044218] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/10/2023] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
DNA methylation, one of the most well-studied epigenetic modifications, is involved in a wide spectrum of biological processes. Epigenetic mechanisms control cellular morphology and function. Such regulatory mechanisms involve histone modifications, chromatin remodeling, DNA methylation, non-coding regulatory RNA molecules, and RNA modifications. One of the most well-studied epigenetic modifications is DNA methylation that plays key roles in development, health, and disease. Our brain is probably the most complex part of our body, with a high level of DNA methylation. A key protein that binds to different types of methylated DNA in the brain is the methyl-CpG binding protein 2 (MeCP2). MeCP2 acts in a dose-dependent manner and its abnormally high or low expression level, deregulation, and/or genetic mutations lead to neurodevelopmental disorders and aberrant brain function. Recently, some of MeCP2-associated neurodevelopmental disorders have emerged as neurometabolic disorders, suggesting a role for MeCP2 in brain metabolism. Of note, MECP2 loss-of-function mutation in Rett Syndrome is reported to cause impairment of glucose and cholesterol metabolism in human patients and/or mouse models of disease. The purpose of this review is to outline the metabolic abnormalities in MeCP2-associated neurodevelopmental disorders that currently have no available cure. We aim to provide an updated overview into the role of metabolic defects associated with MeCP2-mediated cellular function for consideration of future therapeutic strategies.
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Shevkoplyas D, Vuu YM, Davie JR, Rastegar M. The Chromatin Structure at the MECP2 Gene and In Silico Prediction of Potential Coding and Non-Coding MECP2 Splice Variants. Int J Mol Sci 2022; 23:ijms232415643. [PMID: 36555295 PMCID: PMC9779294 DOI: 10.3390/ijms232415643] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/30/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
Methyl CpG binding protein 2 (MeCP2) is an epigenetic reader that binds to methylated CpG dinucleotides and regulates gene transcription. Mecp2/MECP2 gene has 4 exons, encoding for protein isoforms MeCP2E1 and MeCP2E2. MeCP2 plays key roles in neurodevelopment, therefore, its gain- and loss-of-function mutations lead to neurodevelopmental disorders including Rett Syndrome. Here, we describe the structure, functional domains, and evidence support for potential additional alternatively spliced MECP2 transcripts and protein isoforms. We conclude that NCBI MeCP2 isoforms 3 and 4 contain certain MeCP2 functional domains. Our in silico analysis led to identification of histone modification and accessibility profiles at the MECP2 gene and its cis-regulatory elements. We conclude that the human MECP2 gene associated histone post-translational modifications exhibit high similarity between males and females. Between brain regions, histone modifications were found to be less conserved and enriched within larger genomic segments named as "S1-S11". We also identified highly conserved DNA accessibility regions in different tissues and brain regions, named as "A1-A9" and "B1-B9". DNA methylation profile was similar between mid-frontal gyrus of donors 35 days-25 years of age. Based on ATAC-seq data, the identified hypomethylated regions "H1-H8" intersected with most regions of the accessible chromatin (A regions).
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MeCP2 and transcriptional control of eukaryotic gene expression. Eur J Cell Biol 2022; 101:151237. [DOI: 10.1016/j.ejcb.2022.151237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/30/2022] [Accepted: 05/09/2022] [Indexed: 11/19/2022] Open
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Differential Sensitivity of the Protein Translation Initiation Machinery and mTOR Signaling to MECP2 Gain- and Loss-of-Function Involves MeCP2 Isoform-Specific Homeostasis in the Brain. Cells 2022; 11:cells11091442. [PMID: 35563748 PMCID: PMC9105805 DOI: 10.3390/cells11091442] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/15/2022] [Accepted: 04/19/2022] [Indexed: 12/25/2022] Open
Abstract
Eukaryotic gene expression is controlled at multiple levels, including gene transcription and protein translation initiation. One molecule with key roles in both regulatory mechanisms is methyl CpG binding protein 2 (MeCP2). MECP2 gain- and loss-of-function mutations lead to Rett Syndrome and MECP2 Duplication Syndrome, respectively. To study MECP2 gain-of-function, we generated stably transduced human brain cells using lentiviral vectors for both MECP2E1 and MECP2E2 isoforms. Stable overexpression was confirmed by Western blot and immunofluorescence. We assessed the impact of MeCP2E1-E2 gain-of-function on the MeCP2 homeostasis regulatory network (MECP2E1/E2-BDNF/BDNF-miR-132), mTOR-AKT signaling, ribosome biogenesis, markers of chromatin structure, and protein translation initiation. We observed that combined co-transduction of MeCP2 isoforms led to protein degradation of MeCP2E1. Proteosome inhibition by MG132 treatment recovered MeCP2E1 protein within an hour, suggesting its induced degradation through the proteosome pathway. No significant change was detected for translation initiation factors as a result of MeCP2E1, MeCP2E2, or combined overexpression of both isoforms. In contrast, analysis of human Rett Syndrome brains tissues compared with controls indicated impaired protein translation initiation, suggesting that such mechanisms may have differential sensitivity to MECP2 gain- and loss-of-function. Collectively, our results provide further insight towards the dose-dependent functional role of MeCP2 isoforms in the human brain.
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Drake DM, Wells PG. Novel mechanisms in alcohol neurodevelopmental disorders via BRCA1 depletion and BRCA1-dependent NADPH oxidase regulation. Redox Biol 2021; 48:102148. [PMID: 34736119 PMCID: PMC8577473 DOI: 10.1016/j.redox.2021.102148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/20/2021] [Accepted: 09/20/2021] [Indexed: 11/27/2022] Open
Abstract
The breast cancer 1 protein (BRCA1) facilitates DNA repair, preventing embryolethality and protecting the fetus from reactive oxygen species (ROS)-induced developmental disorders mediated by oxidatively damaged DNA. Alcohol (ethanol, EtOH) exposure during pregnancy causes fetal alcohol spectrum disorders (FASD), characterized by aberrant behaviour and enhanced ROS formation and proteasomal protein degradation. Herein, ROS-producing NADPH oxidase (NOX) activity was higher in Brca1 +/- vs. +/+ fetal and adult brains, and further enhanced by a single EtOH exposure. EtOH also enhanced catalase and proteasomal activities, while conversely reducing BRCA1 protein levels without affecting Brca1 gene expression. EtOH-initiated adaptive postnatal freezing behaviour was lost in Brca1 +/- progeny. Pretreatment with the free radical spin trap and ROS inhibitor phenylbutylnitrone blocked all EtOH effects, suggesting ROS-dependent mechanisms. This is the first in vivo evidence of NOX regulation by BRCA1, and of EtOH-induced, ROS-mediated depletion of BRCA1, revealing novel mechanisms of BRCA1 protection in FASD.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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Buist M, Fuss D, Rastegar M. Transcriptional Regulation of MECP2E1-E2 Isoforms and BDNF by Metformin and Simvastatin through Analyzing Nascent RNA Synthesis in a Human Brain Cell Line. Biomolecules 2021; 11:biom11081253. [PMID: 34439919 PMCID: PMC8391797 DOI: 10.3390/biom11081253] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 08/14/2021] [Accepted: 08/19/2021] [Indexed: 12/25/2022] Open
Abstract
Methyl CpG binding protein 2 (MeCP2) is the main DNA methyl-binding protein in the brain that binds to 5-methylcytosine and 5-hydroxymethyl cytosine. MECP2 gene mutations are the main origin of Rett Syndrome (RTT), a neurodevelopmental disorder in young females. The disease has no existing cure, however, metabolic drugs such as metformin and statins have recently emerged as potential therapeutic candidates. In addition, induced MECP2-BDNF homeostasis regulation has been suggested as a therapy avenue. Here, we analyzed nascent RNA synthesis versus steady state total cellular RNA to study the transcriptional effects of metformin (an anti-diabetic drug) on MECP2 isoforms (E1 and E2) and BNDF in a human brain cell line. Additionally, we investigated the impact of simvastatin (a cholesterol lowering drug) on transcriptional regulation of MECP2E1/E2-BDNF. Metformin was capable of post-transcriptionally inducing BDNF and/or MECP2E1, while transcriptionally inhibiting MECP2E2. In contrast simvastatin significantly inhibited BDNF transcription without significantly impacting MECP2E2 transcripts. Further analysis of ribosomal RNA transcripts confirmed that the drug neither individually nor in combination affected these fundamentally important transcripts. Experimental analysis was completed in conditions of the presence or absence of serum starvation that showed minimal impact for serum deprival, although significant inhibition of steady state MECP2E1 by simvastatin was only detected in non-serum starved cells. Taken together, our results suggest that metformin controls MECP2E1/E2-BDNF transcriptionally and/or post-transcriptionally, and that simvastatin is a potent transcriptional inhibitor of BDNF. The transcriptional effect of these drugs on MECP2E1/E2-BDNF were not additive under these tested conditions, however, either drug may have potential application for related disorders.
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Affiliation(s)
| | | | - Mojgan Rastegar
- Correspondence: ; Tel.: +1-(204)-272-3108; Fax: +1-(204)-789-3900
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Mathews E, Dewees K, Diaz D, Favero C. White matter abnormalities in fetal alcohol spectrum disorders: Focus on axon growth and guidance. Exp Biol Med (Maywood) 2021; 246:812-821. [PMID: 33423552 DOI: 10.1177/1535370220980398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fetal Alcohol Spectrum Disorders (FASDs) describe a range of deficits, affecting physical, mental, cognitive, and behavioral function, arising from prenatal alcohol exposure. FASD causes widespread white matter abnormalities, with significant alterations of tracts in the cerebral cortex, cerebellum, and hippocampus. These brain regions present with white-matter volume reductions, particularly at the midline. Neural pathways herein are guided primarily by three guidance cue families: Semaphorin/Neuropilin, Netrin/DCC, and Slit/Robo. These guidance cue/receptor pairs attract and repulse axons and ensure that they reach the proper target to make functional connections. In several cases, these signals cooperate with each other and/or additional molecular partners. Effects of alcohol on guidance cue mechanisms and their associated effectors include inhibition of growth cone response to repellant cues as well as changes in gene expression. Relevant to the corpus callosum, specifically, developmental alcohol exposure alters GABAergic and glutamatergic cell populations and glial cells that serve as guidepost cells for callosal axons. In many cases, deficits seen in FASD mirror aberrancies in guidance cue/receptor signaling. We present evidence for the need for further study on how prenatal alcohol exposure affects the formation of neural connections which may underlie disrupted functional connectivity in FASD.
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Affiliation(s)
- Erin Mathews
- Biology Department, Ursinus College, Collegeville, PA 19426-1000, USA
| | - Kevyn Dewees
- Biology Department, Ursinus College, Collegeville, PA 19426-1000, USA
| | - Deborah Diaz
- Biology Department, Ursinus College, Collegeville, PA 19426-1000, USA
| | - Carlita Favero
- Biology Department, Ursinus College, Collegeville, PA 19426-1000, USA
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Pejhan S, Rastegar M. Role of DNA Methyl-CpG-Binding Protein MeCP2 in Rett Syndrome Pathobiology and Mechanism of Disease. Biomolecules 2021; 11:75. [PMID: 33429932 PMCID: PMC7827577 DOI: 10.3390/biom11010075] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/01/2021] [Accepted: 01/03/2021] [Indexed: 12/16/2022] Open
Abstract
Rett Syndrome (RTT) is a severe, rare, and progressive developmental disorder with patients displaying neurological regression and autism spectrum features. The affected individuals are primarily young females, and more than 95% of patients carry de novo mutation(s) in the Methyl-CpG-Binding Protein 2 (MECP2) gene. While the majority of RTT patients have MECP2 mutations (classical RTT), a small fraction of the patients (atypical RTT) may carry genetic mutations in other genes such as the cyclin-dependent kinase-like 5 (CDKL5) and FOXG1. Due to the neurological basis of RTT symptoms, MeCP2 function was originally studied in nerve cells (neurons). However, later research highlighted its importance in other cell types of the brain including glia. In this regard, scientists benefitted from modeling the disease using many different cellular systems and transgenic mice with loss- or gain-of-function mutations. Additionally, limited research in human postmortem brain tissues provided invaluable findings in RTT pathobiology and disease mechanism. MeCP2 expression in the brain is tightly regulated, and its altered expression leads to abnormal brain function, implicating MeCP2 in some cases of autism spectrum disorders. In certain disease conditions, MeCP2 homeostasis control is impaired, the regulation of which in rodents involves a regulatory microRNA (miR132) and brain-derived neurotrophic factor (BDNF). Here, we will provide an overview of recent advances in understanding the underlying mechanism of disease in RTT and the associated genetic mutations in the MECP2 gene along with the pathobiology of the disease, the role of the two most studied protein variants (MeCP2E1 and MeCP2E2 isoforms), and the regulatory mechanisms that control MeCP2 homeostasis network in the brain, including BDNF and miR132.
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Affiliation(s)
| | - Mojgan Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R3E 0J9, Canada;
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Vriend J, Rastegar M. Ubiquitin ligases and medulloblastoma: genetic markers of the four consensus subgroups identified through transcriptome datasets. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165839. [PMID: 32445667 DOI: 10.1016/j.bbadis.2020.165839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/23/2020] [Accepted: 05/13/2020] [Indexed: 01/05/2023]
Abstract
The ubiquitin proteasome system regulates key cellular processes in normal and in cancer cells. Herein, we review published data on the role of ubiquitin ligases in the four major subgroups of medulloblastoma (MB). While conventional literature serves as an initial source of information on cellular pathways in MB, large publicly available datasets of gene expression can be used to add information not previously identified in the literature. By analysing the publicly available Cavalli dataset, we show that increased expression of ZNRF3 characterizes the WNT subgroup of MB. The ZNRF3 gene codes for an E3 ligase associated with WNT receptors. Loss of a copy of chromosome 6 in a subtype of the WNT group was associated with decreased expression of the gene encoding the E3 ligase RNF146. While the E3 ligase SMURF regulates SHH receptors, increased expression of the gene encoding the Cullin Ring E3 adaptor PPP2R2C was statistically a better genetic marker of the SHH group. Genes whose expression was statistically strongly related to Group 3 included the E3 ligase gene TRIM58, and the gene for the E3 ligase adaptor, PPP2R2B. Group 4 MB was associated with expression of genes encoding several E3 ligases and E3 ligase adaptors involved in ribosome biogenesis. Increased expression of the genes encoding the E3 ligase adaptors and transcription repressors ZBTB18 and ZBTB38 were also noted in subgroup 4. These data suggest that several E3 ligases and their adaptors should be investigated as therapeutic targets for subgroup specific MB brain tumors.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics and Regenerative Medicine Program, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
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Pejhan S, Del Bigio MR, Rastegar M. The MeCP2E1/E2-BDNF- miR132 Homeostasis Regulatory Network Is Region-Dependent in the Human Brain and Is Impaired in Rett Syndrome Patients. Front Cell Dev Biol 2020; 8:763. [PMID: 32974336 PMCID: PMC7471663 DOI: 10.3389/fcell.2020.00763] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/21/2020] [Indexed: 11/13/2022] Open
Abstract
Rett Syndrome (RTT) is a rare and progressive neurodevelopmental disorder that is caused by de novo mutations in the X-linked Methyl CpG binding protein 2 (MECP2) gene and is subjected to X-chromosome inactivation. RTT is commonly associated with neurological regression, autistic features, motor control impairment, seizures, loss of speech and purposeful hand movements, mainly affecting females. Different animal and cellular model systems have tremendously contributed to our current knowledge about MeCP2 and RTT. However, the majority of these findings remain unexamined in the brain of RTT patients. Based on previous studies in rodent brains, the highly conserved neuronal microRNA “miR132” was suggested to be an inhibitor of MeCP2 expression. The neuronal miR132 itself is induced by Brain Derived Neurotrophic Factor (BDNF), a neurotransmitter modulator, which in turn is controlled by MeCP2. This makes the basis of the MECP2-BDNF-miR132 feedback regulatory loop in the brain. Here, we studied the components of this feedback regulatory network in humans, and its possible impairment in the brain of RTT patients. In this regard, we evaluated the transcript and protein levels of MECP2/MeCP2E1 and E2 isoforms, BDNF/BDNF, and miR132 (both 3p and 5p strands) by real time RT-PCR, Western blot, and ELISA in four different regions of the human RTT brains and their age-, post-mortem delay-, and sex-matched controls. The transcript level of the studied elements was significantly compromised in RTT patients, even though the change was not identical in different parts of the brain. Our data indicates that MeCP2E1/E2-BDNF protein levels did not follow their corresponding transcript trends. Correlational studies suggested that the MECP2E1/E2-BDNF-miR132 homeostasis regulation might not be similarly controlled in different parts of the human brain. Despite challenges in evaluating autopsy samples in rare diseases, our findings would help to shed some light on RTT pathobiology, and obscurities caused by limited studies on MeCP2 regulation in the human brain.
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Affiliation(s)
- Shervin Pejhan
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Marc R Del Bigio
- Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Mojgan Rastegar
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
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Pejhan S, Siu VM, Ang LC, Del Bigio MR, Rastegar M. Differential brain region-specific expression of MeCP2 and BDNF in Rett Syndrome patients: a distinct grey-white matter variation. Neuropathol Appl Neurobiol 2020; 46:735-750. [PMID: 32246495 DOI: 10.1111/nan.12619] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 01/03/2020] [Accepted: 03/23/2020] [Indexed: 12/18/2022]
Abstract
INTRODUCTION AND OBJECTIVES Rett Syndrome (RTT) is a neurodevelopmental disorder caused by Methyl CpG Binding Protein 2 (MECP2) gene mutations. Previous studies of MeCP2 in the human brain showed variable and inconsistent mosaic-pattern immunolabelling, which has been interpreted as a reflection of activation-state variability. We aimed to study post mortem MeCP2 and BDNF (MeCP2 target) degradation and brain region-specific detection in relation to RTT pathophysiology. METHODS We investigated MeCP2 and BDNF stabilities in non-RTT human brains by immunohistochemical labelling and compared them in three brain regions of RTT and controls. RESULTS In surgically excised samples of human hippocampus and cerebellum, MeCP2 was universally detected. There was no significantly obvious difference between males and females. However, post mortem delay in autopsy samples had substantial influence on MeCP2 detection. Immunohistochemistry studies in RTT patients showed lower MeCP2 detection in glial cells of the white matter. Glial fibrillary acidic protein (GFAP) expression was also reduced in RTT brain samples without obvious change in myelin basic protein (MBP). Neurons did not show any noticeable decrease in MeCP2 detection. BDNF immunohistochemical detection showed an astroglial/endothelial pattern without noticeable difference between RTT and controls. CONCLUSIONS Our findings indicate that MeCP2 protein is widely expressed in mature human brain cells at all ages. However, our data points towards a possible white matter abnormality in RTT and highlights the importance of studying human RTT brain tissues in parallel with research on animal and cell models of RTT.
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Affiliation(s)
- S Pejhan
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - V M Siu
- Division of Medical Genetics, Department of Paediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - L C Ang
- Department of Pathology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - M R Del Bigio
- Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - M Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
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Amiri S, Davie JR, Rastegar M. Chronic Ethanol Exposure Alters DNA Methylation in Neural Stem Cells: Role of Mouse Strain and Sex. Mol Neurobiol 2020; 57:650-667. [PMID: 31414368 DOI: 10.1007/s12035-019-01728-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 07/31/2019] [Indexed: 12/13/2022]
Abstract
Prenatal alcohol exposure (PAE) is considered as a risk factor for the development of fetal alcohol spectrum disorders (FASD). Evidence indicates that PAE affects epigenetic mechanisms (such as DNA methylation) and alters the normal differentiation and development of neural stem cells (NSC) in the fetal brain. However, PAE effects depend on several factors such as sex and strain of the studied subjects. Here, we investigated whether murine sex and strain contribute to the effects of chronic ethanol exposure on DNA methylation machinery of differentiating NSC. Further, the effects of PAE on glial lineage (including both astrocytes and oligodendrocytes) in a sex- and strain-dependent manner have not been studied yet. To examine the effects of chronic ethanol exposure on gliogenesis, we exposed differentiating NSC to glio-inductive culture conditions. Applying a standard in vitro model system, we treated male and female differentiating NSC (obtained from the forebrain of CD1 and C57BL/6 embryos at embryonic day 14.5) with chronic ethanol exposure (70 mM) for 8 days. We show that ethanol induces global DNA hypomethylation, while altering the expression of DNA methylation-related genes in a sex- and strain-specific manner. The observed change in cellular DNA methylation levels was associated with altered expression of glial markers CNPASE, GFAP, and OLIG2 in CD1 (but not C57BL/6) cells. We conclude that the impact of ethanol effect on DNA methylation is dependent on cellular sex and strain. Also, ethanol impact on neural stem cell fate commitment was only detected in cells isolated from CD1 mouse strain, but not in C57BL/6 cells. The results of the current study provide evidence that sex and strain of rodents (C57BL/6 and CD1) during gestation are important factors, which affect alcohol effects on NSC differentiation and DNA methylation. Results of this study may also help in interpreting data on the developmental toxicity of many compounds during the gestational period.
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Affiliation(s)
- Shayan Amiri
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada
- Regenerative Medicine Program, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada
| | - James R Davie
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada.
- Regenerative Medicine Program, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada.
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Sheikholeslami K, Ali Sher A, Lockman S, Kroft D, Ganjibakhsh M, Nejati-Koshki K, Shojaei S, Ghavami S, Rastegar M. Simvastatin Induces Apoptosis in Medulloblastoma Brain Tumor Cells via Mevalonate Cascade Prenylation Substrates. Cancers (Basel) 2019; 11:cancers11070994. [PMID: 31319483 PMCID: PMC6678292 DOI: 10.3390/cancers11070994] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 02/07/2023] Open
Abstract
Medulloblastoma is a common pediatric brain tumor and one of the main types of solid cancers in children below the age of 10. Recently, cholesterol-lowering “statin” drugs have been highlighted for their possible anti-cancer effects. Clinically, statins are reported to have promising potential for consideration as an adjuvant therapy in different types of cancers. However, the anti-cancer effects of statins in medulloblastoma brain tumor cells are not currently well-defined. Here, we investigated the cell death mechanisms by which simvastatin mediates its effects on different human medulloblastoma cell lines. Simvastatin is a lipophilic drug that inhibits HMG-CoA reductase and has pleotropic effects. Inhibition of HMG-CoA reductase prevents the formation of essential downstream intermediates in the mevalonate cascade, such as farnesyl pyrophosphate (FPP) and gernaylgerany parophosphate (GGPP). These intermediates are involved in the activation pathway of small Rho GTPase proteins in different cell types. We observed that simvastatin significantly induces dose-dependent apoptosis in three different medulloblastoma brain tumor cell lines (Daoy, D283, and D341 cells). Our investigation shows that simvastatin-induced cell death is regulated via prenylation intermediates of the cholesterol metabolism pathway. Our results indicate that the induction of different caspases (caspase 3, 7, 8, and 9) depends on the nature of the medulloblastoma cell line. Western blot analysis shows that simvastatin leads to changes in the expression of regulator proteins involved in apoptosis, such as Bax, Bcl-2, and Bcl-xl. Taken together, our data suggests the potential application of a novel non-classical adjuvant therapy for medulloblastoma, through the regulation of protein prenylation intermediates that occurs via inhibition of the mevalonate pathway.
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Affiliation(s)
- Kimia Sheikholeslami
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada
- Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Annan Ali Sher
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada
| | - Sandhini Lockman
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada
| | - Daniel Kroft
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada
| | - Meysam Ganjibakhsh
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada
| | - Kazem Nejati-Koshki
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada
| | - Shahla Shojaei
- Department of Human Anatomy and Cell Sciences, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
| | - Saeid Ghavami
- Department of Human Anatomy and Cell Sciences, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada
- Research Institute of Oncology and Hematology, CancerCare Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Mojgan Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, BMSB 627, Winnipeg, MB R3E 0J9, Canada.
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DNA Methylation Contributes to the Differential Expression Levels of Mecp2 in Male Mice Neurons and Astrocytes. Int J Mol Sci 2019; 20:ijms20081845. [PMID: 31013990 PMCID: PMC6514911 DOI: 10.3390/ijms20081845] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 02/01/2023] Open
Abstract
Methyl CpG binding protein-2 (MeCP2) isoforms (E1 and E2) are important epigenetic regulators in brain cells. Accordingly, MeCP2 loss- or gain-of-function mutation causes neurodevelopmental disorders, including Rett syndrome (RTT), MECP2 duplication syndrome (MDS), and autism spectrum disorders (ASD). Within different types of brain cells, highest MeCP2 levels are detected in neurons and the lowest in astrocytes. However, our current knowledge of Mecp2/MeCP2 regulatory mechanisms remains largely elusive. It appears that there is a sex-dependent effect in X-linked MeCP2-associated disorders, as RTT primarily affects females, whereas MDS is found almost exclusively in males. This suggests that Mecp2 expression levels in brain cells might be sex-dependent. Here, we investigated the sex- and cell type-specific expression of Mecp2 isoforms in male and female primary neurons and astrocytes isolated from the murine forebrain. Previously, we reported that DNA methylation of six Mecp2 regulatory elements correlated with Mecp2 levels in the brain. We now show that in male brain cells, DNA methylation is significantly correlated with the transcript expression of these two isoforms. We show that both Mecp2 isoforms are highly expressed in male neurons compared to male astrocytes, with Mecp2e1 expressed at higher levels than Mecp2e2. Our data indicate that higher DNA methylation at the Mecp2 regulatory element(s) is associated with lower levels of Mecp2 isoforms in male astrocytes compared to male neurons.
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