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Kalani L, Kim BH, de Chavez AR, Roemer A, Mikhailov A, Merritt JK, Good KV, Chow RL, Delaney KR, Hendzel MJ, Zhou Z, Neul JL, Vincent JB, Ausió J. Testing the PEST hypothesis using relevant Rett mutations in MeCP2 E1 and E2 isoforms. Hum Mol Genet 2024:ddae119. [PMID: 39137370 DOI: 10.1093/hmg/ddae119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 07/19/2024] [Accepted: 08/07/2024] [Indexed: 08/15/2024] Open
Abstract
Mutations in methyl-CpG binding protein 2 (MeCP2), such as the T158M, P152R, R294X, and R306C mutations, are responsible for most Rett syndrome (RTT) cases. These mutations often result in altered protein expression that appears to correlate with changes in the nuclear size; however, the molecular details of these observations are poorly understood. Using a C2C12 cellular system expressing human MeCP2-E1 isoform as well as mouse models expressing these mutations, we show that T158M and P152R result in a decrease in MeCP2 protein, whereas R306C has a milder variation, and R294X resulted in an overall 2.5 to 3 fold increase. We also explored the potential involvement of the MeCP2 PEST domains in the proteasome-mediated regulation of MeCP2. Finally, we used the R294X mutant to gain further insight into the controversial competition between MeCP2 and histone H1 in the chromatin context. Interestingly, in R294X, MeCP2 E1 and E2 isoforms were differently affected, where the E1 isoform contributes to much of the overall protein increase observed, while E2 decreases by half. The modes of MeCP2 regulation, thus, appear to be differently regulated in the two isoforms.
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Affiliation(s)
- Ladan Kalani
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - Bo-Hyun Kim
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - Alberto Ruiz de Chavez
- Department of Biology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - Anastasia Roemer
- Departments of Oncology and Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 11560 University Ave, Edmonton, AB T6G 2H7, Canada
| | - Anna Mikhailov
- Molecular Neuropsychiatry & Development (MiND) Lab, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada
| | - Jonathan K Merritt
- Vanderbilt Kennedy Center, Departments of Pediatrics, Pharmacology, and Special Education, Vanderbilt University Medical Center and Vanderbilt University, 1211 Medical Center Dr, Nashville, TN 37232, United States
| | - Katrina V Good
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
- Molecular Neuropsychiatry & Development (MiND) Lab, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada
| | - Robert L Chow
- Department of Biology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - Kerry R Delaney
- Department of Biology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - Michael J Hendzel
- Departments of Oncology and Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 11560 University Ave, Edmonton, AB T6G 2H7, Canada
| | - Zhaolan Zhou
- Department of Genetics, Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, 3400 Civic Center Blvd, Philadelphia, PA 19104, United States
| | - Jeffrey L Neul
- Vanderbilt Kennedy Center, Departments of Pediatrics, Pharmacology, and Special Education, Vanderbilt University Medical Center and Vanderbilt University, 1211 Medical Center Dr, Nashville, TN 37232, United States
| | - John B Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada
- Institute of Medical Science, University of Toronto, 27 King's College Cir, Toronto, ON M5S 1A8, Canada
- Department of Psychiatry, University of Toronto, 27 King College Cir, Toronto, ON M5T 1R8, Canada
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
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Wang P, Meng Z, Deng K, Gao Z, Cai J. Vpr driving DNA methylation variation of CD4 + T cells in HIV-1 infection. Virol J 2024; 21:97. [PMID: 38671522 PMCID: PMC11046818 DOI: 10.1186/s12985-024-02363-5] [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: 02/04/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Despite the existence of available therapeutic interventions for HIV-1, this virus remains a significant global threat, leading to substantial morbidity and mortality. Within HIV-1-infected cells, the accessory viral protein r (Vpr) exerts control over diverse biological processes, including cell cycle progression, DNA repair, and apoptosis. The regulation of gene expression through DNA methylation plays a crucial role in physiological processes, exerting its influence without altering the underlying DNA sequence. However, a thorough examination of the impact of Vpr on DNA methylation in human CD4 + T cells has not been conducted. METHODS In this study, we employed base-resolution whole-genome bisulfite sequencing (WGBS), real-time quantitative RCR and western blot to explore the effect of Vpr on DNA methylation of host cells under HIV-1 infection. RESULTS We observed that HIV-1 infection leads to elevated levels of global DNA methylation in primary CD4 + T cells. Specifically, Vpr induces significant modifications in DNA methylation patterns, particularly affecting regions within promoters and gene bodies. These alterations notably influence genes related to immune-related pathways and olfactory receptor activity. Moreover, Vpr demonstrates a distinct ability to diminish the levels of methylation in histone genes. CONCLUSIONS These findings emphasize the significant involvement of Vpr in regulating transcription through the modulation of DNA methylation patterns. Together, the results of this investigation will considerably enhance our understanding of the influence of HIV-1 Vpr on the DNA methylation of host cells, offer potential avenues for the development of more effective treatments.
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Affiliation(s)
- Peipei Wang
- Department of Infectious Diseases, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Zhuoyue Meng
- Institute of Human Virology, Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Kai Deng
- Institute of Human Virology, Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Zhiliang Gao
- Department of Infectious Diseases, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Jinfeng Cai
- Institute of Human Virology, Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
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Kalani L, Kim BH, Vincent JB, Ausió J. MeCP2 ubiquitination and sumoylation, in search of a function†. Hum Mol Genet 2023; 33:1-11. [PMID: 37694858 DOI: 10.1093/hmg/ddad150] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 09/12/2023] Open
Abstract
MeCP2 (Methyl CpG binding protein 2) is an intrinsically disordered protein that binds to methylated genome regions. The protein is a critical transcriptional regulator of the brain, and its mutations account for 95% of Rett syndrome (RTT) cases. Early studies of this neurodevelopmental disorder revealed a close connection with dysregulations of the ubiquitin system (UbS), notably as related to UBE3A, a ubiquitin ligase involved in the proteasome-mediated degradation of proteins. MeCP2 undergoes numerous post-translational modifications (PTMs), including ubiquitination and sumoylation, which, in addition to the potential functional outcomes of their monomeric forms in gene regulation and synaptic plasticity, in their polymeric organization, these modifications play a critical role in proteasomal degradation. UbS-mediated proteasomal degradation is crucial in maintaining MeCP2 homeostasis for proper function and is involved in decreasing MeCP2 in some RTT-causing mutations. However, regardless of all these connections to UbS, the molecular details involved in the signaling of MeCP2 for its targeting by the ubiquitin-proteasome system (UPS) and the functional roles of monomeric MeCP2 ubiquitination and sumoylation remain largely unexplored and are the focus of this review.
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Affiliation(s)
- Ladan Kalani
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - Bo-Hyun Kim
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
| | - John B Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada
- Institute of Medical Science, University of Toronto, 27 King's College Cir, Toronto, ON M5S 1A8, Canada
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8W 2Y2, Canada
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Siqueira E, Kim BH, Reser L, Chow R, Delaney K, Esteller M, Ross MM, Shabanowitz J, Hunt DF, Guil S, Ausió J. Analysis of the interplay between MeCP2 and histone H1 during in vitro differentiation of human ReNCell neural progenitor cells. Epigenetics 2023; 18:2276425. [PMID: 37976174 PMCID: PMC10769555 DOI: 10.1080/15592294.2023.2276425] [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: 06/13/2023] [Accepted: 10/18/2023] [Indexed: 11/19/2023] Open
Abstract
An immortalized neural cell line derived from the human ventral mesencephalon, called ReNCell, and its MeCP2 knock out were used. With it, we characterized the chromatin compositional transitions undergone during differentiation, with special emphasis on linker histones. While the WT cells displayed the development of dendrites and axons the KO cells did not, despite undergoing differentiation as monitored by NeuN. ReNCell expressed minimal amounts of histone H1.0 and their linker histone complement consisted mainly of histone H1.2, H1.4 and H1.5. The overall level of histone H1 exhibited a trend to increase during the differentiation of MeCP2 KO cells. The phosphorylation levels of histone H1 proteins decreased dramatically during ReNCell's cell differentiation independently of the presence of MeCP2. Immunofluorescence analysis showed that MeCP2 exhibits an extensive co-localization with linker histones. Interestingly, the average size of the nucleus decreased during differentiation but in the MeCP2 KO cells, the smaller size of the nuclei at the start of differentiation increased by almost 40% after differentiation by 8 days (8 DIV). In summary, our data provide a compelling perspective on the dynamic changes of H1 histones during neural differentiation, coupled with the intricate interplay between H1 variants and MeCP2.Abbreviations: ACN, acetonitrile; A230, absorbance at 230 nm; bFGF, basic fibroblast growth factor; CM, chicken erythrocyte histone marker; CNS, central nervous system; CRISPR, clustered regulated interspaced short palindromic repeatsDAPI, 4,'6-diaminidino-2-phenylindole; DIV, days in vitro (days after differentiation is induced); DMEM, Dulbecco's modified Eagle medium; EGF, epidermal growth factor; ESC, embryonic stem cell; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GFAP, glial fibrillary acidic proteinHPLC, high-performance liquid chromatography; IF, immunofluorescence; iPSCs, induced pluripotent stem cells; MAP2, microtubule-associated protein 2; MBD, methyl-binding domain; MeCP2, methyl-CpG binding protein 2; MS, mass spectrometry; NCP, nucleosome core particle; NeuN, neuron nuclear antigen; NPC, neural progenitor cellPAGE, polyacrylamide gel electrophoresis; PBS, phosphate buffered saline; PFA, paraformaldehyde; PTM, posttranslational modification; RP-HPLC, reversed phase HPLC; ReNCells, ReNCells VM; RPLP0, ribosomal protein lateral stalk subunit P0; RT-qPCR, reverse transcription quantitative polymerase-chain reaction; RTT, Rett Syndrome; SDS, sodium dodecyl sulphate; TAD, topologically associating domain; Triple KO, triple knockout.
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Affiliation(s)
- Edilene Siqueira
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, Barcelona, Catalonia, Spain
- National Council for Scientific and Technological Development (CNPq), Brasilia, Federal District, Brazil
| | - Bo-Hyun Kim
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Larry Reser
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Robert Chow
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Kerry Delaney
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Manel Esteller
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, Barcelona, Catalonia, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, Spain
- Physiological Sciences Department, School of Medicine and Health Sciences, University of Barcelona (UB), Barcelona, Catalonia, Spain
| | - Mark M. Ross
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Jeffrey Shabanowitz
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Donald F. Hunt
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
- Department of Pathology, University of Virginia, Charlottesville, Virginia, USA
| | - Sonia Guil
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, Barcelona, Catalonia, Spain
- GermansTrias i Pujol Health Science Research Institute, Badalona, Barcelona, Catalonia, Spain
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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Arumugam T, Ramphal U, Adimulam T, Chinniah R, Ramsuran V. Deciphering DNA Methylation in HIV Infection. Front Immunol 2021; 12:795121. [PMID: 34925380 PMCID: PMC8674454 DOI: 10.3389/fimmu.2021.795121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/17/2021] [Indexed: 12/13/2022] Open
Abstract
With approximately 38 million people living with HIV/AIDS globally, and a further 1.5 million new global infections per year, it is imperative that we advance our understanding of all factors contributing to HIV infection. While most studies have focused on the influence of host genetic factors on HIV pathogenesis, epigenetic factors are gaining attention. Epigenetics involves alterations in gene expression without altering the DNA sequence. DNA methylation is a critical epigenetic mechanism that influences both viral and host factors. This review has five focal points, which examines (i) fluctuations in the expression of methylation modifying factors upon HIV infection (ii) the effect of DNA methylation on HIV viral genes and (iii) host genome (iv) inferences from other infectious and non-communicable diseases, we provide a list of HIV-associated host genes that are regulated by methylation in other disease models (v) the potential of DNA methylation as an epi-therapeutic strategy and biomarker. DNA methylation has also been shown to serve as a robust therapeutic strategy and precision medicine biomarker against diseases such as cancer and autoimmune conditions. Despite new drugs being discovered for HIV, drug resistance is a problem in high disease burden settings such as Sub-Saharan Africa. Furthermore, genetic therapies that are under investigation are irreversible and may have off target effects. Alternative therapies that are nongenetic are essential. In this review, we discuss the potential role of DNA methylation as a novel therapeutic intervention against HIV.
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Affiliation(s)
- Thilona Arumugam
- School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Upasana Ramphal
- School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
- Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine & Medical Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Theolan Adimulam
- School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Romona Chinniah
- School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Veron Ramsuran
- School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
- Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine & Medical Sciences, University of KwaZulu-Natal, Durban, South Africa
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Sharifi O, Yasui DH. The Molecular Functions of MeCP2 in Rett Syndrome Pathology. Front Genet 2021; 12:624290. [PMID: 33968128 PMCID: PMC8102816 DOI: 10.3389/fgene.2021.624290] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 02/08/2021] [Indexed: 12/13/2022] Open
Abstract
MeCP2 protein, encoded by the MECP2 gene, binds to DNA and affects transcription. Outside of this activity the true range of MeCP2 function is still not entirely clear. As MECP2 gene mutations cause the neurodevelopmental disorder Rett syndrome in 1 in 10,000 female births, much of what is known about the biologic function of MeCP2 comes from studying human cell culture models and rodent models with Mecp2 gene mutations. In this review, the full scope of MeCP2 research available in the NIH Pubmed (https://pubmed.ncbi.nlm.nih.gov/) data base to date is considered. While not all original research can be mentioned due to space limitations, the main aspects of MeCP2 and Rett syndrome research are discussed while highlighting the work of individual researchers and research groups. First, the primary functions of MeCP2 relevant to Rett syndrome are summarized and explored. Second, the conflicting evidence and controversies surrounding emerging aspects of MeCP2 biology are examined. Next, the most obvious gaps in MeCP2 research studies are noted. Finally, the most recent discoveries in MeCP2 and Rett syndrome research are explored with a focus on the potential and pitfalls of novel treatments and therapies.
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Affiliation(s)
- Osman Sharifi
- LaSalle Laboratory, Department of Medical Microbiology and Immunology, UC Davis School of Medicine, Davis, CA, United States
| | - Dag H Yasui
- LaSalle Laboratory, Department of Medical Microbiology and Immunology, UC Davis School of Medicine, Davis, CA, United States
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Good KV, Vincent JB, Ausió J. MeCP2: The Genetic Driver of Rett Syndrome Epigenetics. Front Genet 2021; 12:620859. [PMID: 33552148 PMCID: PMC7859524 DOI: 10.3389/fgene.2021.620859] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/05/2021] [Indexed: 12/24/2022] Open
Abstract
Mutations in methyl CpG binding protein 2 (MeCP2) are the major cause of Rett syndrome (RTT), a rare neurodevelopmental disorder with a notable period of developmental regression following apparently normal initial development. Such MeCP2 alterations often result in changes to DNA binding and chromatin clustering ability, and in the stability of this protein. Among other functions, MeCP2 binds to methylated genomic DNA, which represents an important epigenetic mark with broad physiological implications, including neuronal development. In this review, we will summarize the genetic foundations behind RTT, and the variable degrees of protein stability exhibited by MeCP2 and its mutated versions. Also, past and emerging relationships that MeCP2 has with mRNA splicing, miRNA processing, and other non-coding RNAs (ncRNA) will be explored, and we suggest that these molecules could be missing links in understanding the epigenetic consequences incurred from genetic ablation of this important chromatin modifier. Importantly, although MeCP2 is highly expressed in the brain, where it has been most extensively studied, the role of this protein and its alterations in other tissues cannot be ignored and will also be discussed. Finally, the additional complexity to RTT pathology introduced by structural and functional implications of the two MeCP2 isoforms (MeCP2-E1 and MeCP2-E2) will be described. Epigenetic therapeutics are gaining clinical popularity, yet treatment for Rett syndrome is more complicated than would be anticipated for a purely epigenetic disorder, which should be taken into account in future clinical contexts.
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Affiliation(s)
- Katrina V. Good
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - John B. Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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Genomic mosaicism in the pathogenesis and inheritance of a Rett syndrome cohort. Genet Med 2018; 21:1330-1338. [PMID: 30405208 PMCID: PMC6752670 DOI: 10.1038/s41436-018-0348-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 10/17/2018] [Indexed: 01/01/2023] Open
Abstract
PURPOSE To determine the role of mosaicism in the pathogenesis and inheritance of Rett and Rett-like disorders. METHODS We recruited 471 Rett and Rett-like patients. Panel-sequencing targeting MECP2, CDKL5, and FOXG1 was performed. Mosaicism was quantified in 147 patients by a Bayesian genotyper. Candidates were validated by amplicon sequencing and digital PCR. Germline mosaicism of 21 fathers with daughters carrying pathogenic MECP2 variants was further quantified. RESULTS Pathogenic variants of MECP2/CDKL5/FOXG1 were found in 324/471 (68.7%) patients. Somatic MECP2 mosaicism was confirmed in 5/471 (1.1%) patients, including 3/18 males (16.7%) and 2/453 females (0.4%). Three of the five patients with somatic MECP2 mosaicism had mosaicism at MECP2-Arg106. Germline MECP2 mosaicism was detected in 5/21 (23.8%) fathers. CONCLUSION This is the first systematic screening of somatic and paternal germline MECP2 mosaicism at a cohort level. Our findings indicate that somatic MECP2 mosaicism contributes directly to the pathogenicity of Rett syndrome, especially in male patients. MECP2-Arg106 might be a mosaic hotspot. The high proportion of paternal germline MECP2 mosaicism indicates an underestimated mechanism underlying the paternal origin bias of MECP2 variants. Finally, this study provides an empirical foundation for future studies of genetic disorders caused by de novo variations of strong paternal origin.
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Good KV, Martínez de Paz A, Tyagi M, Cheema MS, Thambirajah AA, Gretzinger TL, Stefanelli G, Chow RL, Krupke O, Hendzel M, Missiaen K, Underhill A, Landsberger N, Ausió J. Trichostatin A decreases the levels of MeCP2 expression and phosphorylation and increases its chromatin binding affinity. Epigenetics 2017; 12:934-944. [PMID: 29099289 DOI: 10.1080/15592294.2017.1380760] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
MeCP2 binds to methylated DNA in a chromatin context and has an important role in cancer and brain development and function. Histone deacetylase (HDAC) inhibitors are currently being used to palliate many cancer and neurological disorders. Yet, the molecular mechanisms involved are not well known for the most part and, in particular, the relationship between histone acetylation and MeCP2 is not well understood. In this paper, we study the effect of the HDAC inhibitor trichostatin A (TSA) on MeCP2, a protein whose dysregulation plays an important role in these diseases. We find that treatment of cells with TSA decreases the phosphorylation state of this protein and appears to result in a higher MeCP2 chromatin binding affinity. Yet, the binding dynamics with which the protein binds to DNA appear not to be significantly affected despite the chromatin reorganization resulting from the high levels of acetylation. HDAC inhibition also results in an overall decrease in MeCP2 levels of different cell lines. Moreover, we show that miR132 increases upon TSA treatment, and is one of the players involved in the observed downregulation of MeCP2.
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Affiliation(s)
- Katrina V Good
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Alexia Martínez de Paz
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Monica Tyagi
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Manjinder S Cheema
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Anita A Thambirajah
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada.,b Douglas Hospital Research Center , Department of Psychiatry , McGill University , Montréal , Québec H3G 1Y6 , Canada
| | - Taylor L Gretzinger
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Gilda Stefanelli
- c Department of Medical Biotechnology and Translational Medicine , University of Milan , Milan , Italy
| | - Robert L Chow
- d Department of Biology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Oliver Krupke
- d Department of Biology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
| | - Michael Hendzel
- e Department of Cell Biology , Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta , Canada.,f Department of Oncology and Department of Cell Biology , Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta , Canada
| | - Kristal Missiaen
- f Department of Oncology and Department of Cell Biology , Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta , Canada
| | - Alan Underhill
- f Department of Oncology and Department of Cell Biology , Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta , Canada
| | - Nicoletta Landsberger
- c Department of Medical Biotechnology and Translational Medicine , University of Milan , Milan , Italy
| | - Juan Ausió
- a Department of Biochemistry and Microbiology , University of Victoria , Victoria , BC , V8W 3P6 , Canada
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Stem Cell Technology for (Epi)genetic Brain Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 978:443-475. [PMID: 28523560 DOI: 10.1007/978-3-319-53889-1_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite the enormous efforts of the scientific community over the years, effective therapeutics for many (epi)genetic brain disorders remain unidentified. The common and persistent failures to translate preclinical findings into clinical success are partially attributed to the limited efficiency of current disease models. Although animal and cellular models have substantially improved our knowledge of the pathological processes involved in these disorders, human brain research has generally been hampered by a lack of satisfactory humanized model systems. This, together with our incomplete knowledge of the multifactorial causes in the majority of these disorders, as well as a thorough understanding of associated (epi)genetic alterations, has been impeding progress in gaining more mechanistic insights from translational studies. Over the last years, however, stem cell technology has been offering an alternative approach to study and treat human brain disorders. Owing to this technology, we are now able to obtain a theoretically inexhaustible source of human neural cells and precursors in vitro that offer a platform for disease modeling and the establishment of therapeutic interventions. In addition to the potential to increase our general understanding of how (epi)genetic alterations contribute to the pathology of brain disorders, stem cells and derivatives allow for high-throughput drugs and toxicity testing, and provide a cell source for transplant therapies in regenerative medicine. In the current chapter, we will demonstrate the validity of human stem cell-based models and address the utility of other stem cell-based applications for several human brain disorders with multifactorial and (epi)genetic bases, including Parkinson's disease (PD), Alzheimer's disease (AD), fragile X syndrome (FXS), Angelman syndrome (AS), Prader-Willi syndrome (PWS), and Rett syndrome (RTT).
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11
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MeCP2, A Modulator of Neuronal Chromatin Organization Involved in Rett Syndrome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 978:3-21. [PMID: 28523538 DOI: 10.1007/978-3-319-53889-1_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
From an epigenetic perspective, the genomic chromatin organization of neurons exhibits unique features when compared to somatic cells. Methyl CpG binding protein 2 (MeCP2), through its ability to bind to methylated DNA, seems to be a major player in regulating such unusual organization. An important contribution to this uniqueness stems from the intrinsically disordered nature of this highly abundant chromosomal protein in neurons. Upon its binding to methylated/hydroxymethylated DNA, MeCP2 is able to recruit a plethora of interacting protein and RNA partners. The final outcome is a highly specialized chromatin organization wherein linker histones (histones of the H1 family) and MeCP2 share an organizational role that dynamically changes during neuronal development and that it is still poorly understood. MeCP2 mutations alter its chromatin-binding dynamics and/or impair the ability of the protein to interact with some of its partners, resulting in Rett syndrome (RTT). Therefore, deciphering the molecular details involved in the MeCP2 neuronal chromatin arrangement is critical for our understanding of the proper and altered functionality of these cells.
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Claveria-Gimeno R, Abian O, Velazquez-Campoy A, Ausió J. MeCP2… Nature’s Wonder Protein or Medicine’s Most Feared One? CURRENT GENETIC MEDICINE REPORTS 2016. [DOI: 10.1007/s40142-016-0107-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Khrapunov S, Tao Y, Cheng H, Padlan C, Harris R, Galanopoulou AS, Greally JM, Girvin ME, Brenowitz M. MeCP2 Binding Cooperativity Inhibits DNA Modification-Specific Recognition. Biochemistry 2016; 55:4275-85. [PMID: 27420643 DOI: 10.1021/acs.biochem.6b00451] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Methyl-CpG binding protein 2 (MeCP2) is a multifunctional protein that guides neuronal development through its binding to DNA, recognition of sites of methyl-CpG (mCpG) DNA modification, and interaction with other regulatory proteins. Our study explores the relationship between mCpG and hydroxymethyl-CpG (hmCpG) recognition mediated by its mCpG binding domain (MBD) and binding cooperativity mediated by its C-terminal polypeptide. Previous study of the isolated MBD of MeCP2 documented an unusual mechanism by which ion uptake is required for discrimination of mCpG and hmCpG from CpG. MeCP2 binding cooperativity suppresses discrimination of modified DNA and is highly sensitive to both the total ion concentration and the type of counterions. Higher than physiological total ion concentrations completely suppress MeCP2 binding cooperativity, indicating a dominant electrostatic component to the interaction. Substitution of SO4(2-) for Cl(-) at physiological total ion concentrations also suppresses MeCP2 binding cooperativity, This effect is of particular note as the intracellular Cl(-) concentration changes during neuronal development. A related effect is that the protein-stabilizing solutes, TMAO and glutamate, reduce MeCP2 (but not isolated MBD) binding affinity by 2 orders of magnitude without affecting the apparent binding cooperativity. These observations suggest that polypeptide flexibility facilitates DNA binding by MeCP2. Consistent with this view, nuclear magnetic resonance (NMR) analyses show that ions have discrete effects on the structure of MeCP2, both MBD and the C-terminal domains. Notably, anion substitution results in changes in the NMR chemical shifts of residues, including some whose mutation causes the autism spectrum disorder Rett syndrome. Binding cooperativity makes MeCP2 an effective competitor with histone H1 for accessible DNA sites. The relationship between MeCP2 binding specificity and cooperativity is discussed in the context of chromatin binding, neuronal function, and neuronal development.
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Affiliation(s)
- Sergei Khrapunov
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Yisong Tao
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Huiyong Cheng
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Camille Padlan
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Richard Harris
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Aristea S Galanopoulou
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - John M Greally
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Mark E Girvin
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Michael Brenowitz
- Department of Biochemistry, ‡Departments of Neurology and Neuroscience, and §Department of Genetics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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Della Ragione F, Vacca M, Fioriniello S, Pepe G, D'Esposito M. MECP2, a multi-talented modulator of chromatin architecture. Brief Funct Genomics 2016; 15:420-431. [PMID: 27296483 DOI: 10.1093/bfgp/elw023] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has been a long trip from 1992, the year of the discovery of MECP2, to the present day. What is surprising is that some of the pivotal roles of MeCP2 were already postulated at that time, such as repression of inappropriate expression from repetitive elements and the regulation of pericentric heterochromatin condensation. However, MeCP2 performs many more functions. MeCP2 is a reader of epigenetic information contained in methylated (and hydroxymethylated) DNA, moving from the 'classical' CpG doublet to the more complex view addressed by the non-CpG methylation, which is a feature of the postnatal brain. MECP2 is a transcriptional repressor, although when it forms complexes with the appropriate molecules, it can become a transcriptional activator. For all of these aspects, Rett syndrome, which is caused by MECP2 mutations, is considered a paradigmatic example of a 'chromatin disorder'. Even if the hunt for bona-fide MECP2 target genes is far from concluded today, the role of MeCP2 in the maintenance of chromatin architecture appears to be clearly established. Taking a cue from the non-scientific literature, we can firmly attest that MeCP2 is a player with 'a great future behind it'*.*V. Gassmann 'Un grande avvenire dietro le spalle'. TEA Eds.
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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.
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Affiliation(s)
- Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6 Canada
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16
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Rett Syndrome Mutant Neural Cells Lacks MeCP2 Immunoreactive Bands. PLoS One 2016; 11:e0153262. [PMID: 27064487 PMCID: PMC4827835 DOI: 10.1371/journal.pone.0153262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/26/2016] [Indexed: 11/19/2022] Open
Abstract
Dysfunctions of MeCP2 protein lead to various neurological disorders such as Rett syndrome and Autism. The exact functions of MeCP2 protein is still far from clear. At a molecular level, there exist contradictory data. MeCP2 protein is considered a single immunoreactive band around 75 kDa by western-blot analysis but several reports have revealed the existence of multiple MeCP2 immunoreactive bands above and below the level where MeCP2 is expected. MeCP2 immunoreactive bands have been interpreted in different ways. Some researchers suggest that multiple MeCP2 immunoreactive bands are unidentified proteins that cross-react with the MeCP2 antibody or degradation product of MeCP2, while others suggest that MeCP2 post-transcriptional processing generates multiple molecular forms linked to cell signaling, but so far they have not been properly analyzed in relation to Rett syndrome experimental models. The purpose of this study is to advance understanding of multiple MeCP2 immunoreactive bands in control neural cells and p.T158M MeCP2e1 mutant cells. We have generated stable wild-type and p.T158M MeCP2e1-RFP mutant expressing cells. Application of N- and C- terminal MeCP2 antibodies, and also, RFP antibody minimized concerns about nonspecific cross-reactivity, since they react with the same antigen at different epitopes. We report the existence of multiple MeCP2 immunoreactive bands in control cells, stable wild-type and p.T158M MeCP2e1-RFP mutant expressing cells. Also, MeCP2 immunoreactive bands differences were found between wild-type and p.T158M MeCP2e1-RFP mutant expressing cells. Slower migration phosphorylated band around 70kDa disappeared in p.T158M MeCP2e1-RFP mutant expressing cells. These data suggest that threonine 158 could represent an important phosphorylation site potentially involved in protein function. Our results clearly indicate that MeCP2 antibodies have no cross-reactivity with similar epitopes on others proteins, supporting the idea that MeCP2 may exist in multiple different molecular forms and that molecular pattern variations derived from altered post-transcriptional processing may underlay Rett syndrome physiophatology.
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17
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MeCP2 regulation of cardiac fibroblast proliferation and fibrosis by down-regulation of DUSP5. Int J Biol Macromol 2016; 82:68-75. [DOI: 10.1016/j.ijbiomac.2015.10.076] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 01/07/2023]
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Linhoff MW, Garg SK, Mandel G. A high-resolution imaging approach to investigate chromatin architecture in complex tissues. Cell 2015; 163:246-55. [PMID: 26406379 DOI: 10.1016/j.cell.2015.09.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 05/22/2015] [Accepted: 08/11/2015] [Indexed: 01/08/2023]
Abstract
We present ChromATin, a quantitative high-resolution imaging approach for investigating chromatin organization in complex tissues. This method combines analysis of epigenetic modifications by immunostaining, localization of specific DNA sequences by FISH, and high-resolution segregation of nuclear compartments using array tomography (AT) imaging. We then apply this approach to examine how the genome is organized in the mammalian brain using female Rett syndrome mice, which are a mosaic of normal and Mecp2-null cells. Side-by-side comparisons within the same field reveal distinct heterochromatin territories in wild-type neurons that are altered in Mecp2-null nuclei. Mutant neurons exhibit increased chromatin compaction and a striking redistribution of the H4K20me3 histone modification into pericentromeric heterochromatin, a territory occupied normally by MeCP2. These events are not observed in every neuronal cell type, highlighting ChromATin as a powerful in situ method for examining cell-type-specific differences in chromatin architecture in complex tissues.
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Affiliation(s)
- Michael W Linhoff
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Saurabh K Garg
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Howard Hughes Medical Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Gail Mandel
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Howard Hughes Medical Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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Du Q, Luu PL, Stirzaker C, Clark SJ. Methyl-CpG-binding domain proteins: readers of the epigenome. Epigenomics 2015; 7:1051-73. [DOI: 10.2217/epi.15.39] [Citation(s) in RCA: 265] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
How DNA methylation is interpreted and influences genome regulation remains largely unknown. Proteins of the methyl-CpG-binding domain (MBD) family are primary candidates for the readout of DNA methylation as they recruit chromatin remodelers, histone deacetylases and methylases to methylated DNA associated with gene repression. MBD protein binding requires both functional MBD domains and methyl-CpGs; however, some MBD proteins also bind unmethylated DNA and active regulatory regions via alternative regulatory domains or interaction with the nucleosome remodeling deacetylase (NuRD/Mi-2) complex members. Mutations within MBD domains occur in many diseases, including neurological disorders and cancers, leading to loss of MBD binding specificity to methylated sites and gene deregulation. Here, we summarize the current state of knowledge about MBD proteins and their role as readers of the epigenome.
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Affiliation(s)
- Qian Du
- Epigenetics Research Laboratory, Genomics & Epigenetics Division, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - Phuc-Loi Luu
- Epigenetics Research Laboratory, Genomics & Epigenetics Division, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
| | - Clare Stirzaker
- Epigenetics Research Laboratory, Genomics & Epigenetics Division, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
- St Vincent's Clinical School, University of NSW, Darlinghurst, NSW 2010, Australia
| | - Susan J Clark
- Epigenetics Research Laboratory, Genomics & Epigenetics Division, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia
- St Vincent's Clinical School, University of NSW, Darlinghurst, NSW 2010, Australia
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Rietveld L, Stuss DP, McPhee D, Delaney KR. Genotype-specific effects of Mecp2 loss-of-function on morphology of Layer V pyramidal neurons in heterozygous female Rett syndrome model mice. Front Cell Neurosci 2015; 9:145. [PMID: 25941473 PMCID: PMC4403522 DOI: 10.3389/fncel.2015.00145] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 03/29/2015] [Indexed: 01/29/2023] Open
Abstract
Rett syndrome (RTT) is a progressive neurological disorder primarily caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). The heterozygous female brain consists of mosaic of neurons containing both wild-type MeCP2 (MeCP2+) and mutant MeCP2 (MeCP2-). Three-dimensional morphological analysis was performed on individually genotyped layer V pyramidal neurons in the primary motor cortex of heterozygous (Mecp2(+/-) ) and wild-type (Mecp2(+/+) ) female mice ( > 6 mo.) from the Mecp2(tm1.1Jae) line. Comparing basal dendrite morphology, soma and nuclear size of MeCP2+ to MeCP2- neurons reveals a significant cell autonomous, genotype specific effect of Mecp2. MeCP2- neurons have 15% less total basal dendritic length, predominantly in the region 70-130 μm from the cell body and on average three fewer branch points, specifically loss in the second and third branch orders. Soma and nuclear areas of neurons of mice were analyzed across a range of ages (5-21 mo.) and X-chromosome inactivation (XCI) ratios (12-56%). On average, MeCP2- somata and nuclei were 15 and 13% smaller than MeCP2+ neurons respectively. In most respects branching morphology of neurons in wild-type brains (MeCP2 WT) was not distinguishable from MeCP2+ but somata and nuclei of MeCP2 WT neurons were larger than those of MeCP2+ neurons. These data reveal cell autonomous effects of Mecp2 mutation on dendritic morphology, but also suggest non-cell autonomous effects with respect to cell size. MeCP2+ and MeCP2- neuron sizes were not correlated with age, but were correlated with XCI ratio. Unexpectedly the MeCP2- neurons were smallest in brains where the XCI ratio was highly skewed toward MeCP2+, i.e., wild-type. This raises the possibility of cell non-autonomous effects that act through mechanisms other than globally secreted factors; perhaps competition for synaptic connections influences cell size and morphology in the genotypically mosaic brain of RTT model mice.
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Affiliation(s)
- Leslie Rietveld
- Department of Biology, University of Victoria Victoria, BC, Canada
| | - David P Stuss
- Department of Biology, University of Victoria Victoria, BC, Canada
| | - David McPhee
- Department of Biology, University of Victoria Victoria, BC, Canada
| | - Kerry R Delaney
- Department of Biology, University of Victoria Victoria, BC, Canada
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Liyanage VRB, Zachariah RM, Davie JR, Rastegar M. Ethanol deregulates Mecp2/MeCP2 in differentiating neural stem cells via interplay between 5-methylcytosine and 5-hydroxymethylcytosine at the Mecp2 regulatory elements. Exp Neurol 2015; 265:102-17. [PMID: 25620416 DOI: 10.1016/j.expneurol.2015.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 12/23/2014] [Accepted: 01/18/2015] [Indexed: 11/29/2022]
Abstract
Methyl CpG Binding Protein 2 (MeCP2) is an important epigenetic factor in the brain. MeCP2 expression is affected by different environmental insults including alcohol exposure. Accumulating evidence supports the role of aberrant MeCP2 expression in ethanol exposure-induced neurological symptoms. However, the underlying molecular mechanisms of ethanol-induced MeCP2 deregulation remain elusive. To study the effect of ethanol on Mecp2/MeCP2 expression during neurodifferentiation, we established an in vitro model of ethanol exposure, using differentiating embryonic brain-derived neural stem cells (NSC). Previously, we demonstrated the impact of DNA methylation at the Mecp2 regulatory elements (REs) on Mecp2/MeCP2 expression in vitro and in vivo. Here, we studied whether altered DNA methylation at these REs is associated with the Mecp2/MeCP2 misexpression induced by ethanol. Binge-like and continuous ethanol exposure upregulated Mecp2/MeCP2, while ethanol withdrawal downregulated its expression. DNA methylation analysis by methylated DNA immunoprecipitation indicated that increased 5-hydroxymethylcytosine (5hmC) and decreased 5-methylcytosine (5mC) enrichment at specific REs were associated with upregulated Mecp2/MeCP2 following continuous ethanol exposure. The reduced Mecp2/MeCP2 expression upon ethanol withdrawal was associated with reduced 5hmC and increased 5mC enrichment at these REs. Moreover, ethanol altered global DNA methylation (5mC and 5hmC). Under the tested conditions, ethanol had minimal effects on NSC cell fate commitment, but caused changes in neuronal morphology and glial cell size. Taken together, our data represent an epigenetic mechanism for ethanol-mediated misexpression of Mecp2/MeCP2 in differentiating embryonic brain cells. We also show the potential role of DNA methylation and MeCP2 in alcohol-related neurological disorders, specifically Fetal Alcohol Spectrum Disorders.
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Affiliation(s)
- Vichithra Rasangi Batuwita Liyanage
- Regenerative Medicine Program, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada; Department of Biochemistry and Medical Genetics, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada.
| | - Robby Mathew Zachariah
- Regenerative Medicine Program, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada; Department of Biochemistry and Medical Genetics, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada.
| | - James Ronald Davie
- Department of Biochemistry and Medical Genetics, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada.
| | - Mojgan Rastegar
- Regenerative Medicine Program, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada; Department of Biochemistry and Medical Genetics, College of Medicine, Faculty of Health Sciences, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, Manitoba R3E 0J9, Canada.
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Ausió J, Paz AMD, Esteller M. MeCP2: the long trip from a chromatin protein to neurological disorders. Trends Mol Med 2014; 20:487-98. [DOI: 10.1016/j.molmed.2014.03.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 12/13/2022]
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Khrapunov S, Warren C, Cheng H, Berko E, Greally JM, Brenowitz M. Unusual characteristics of the DNA binding domain of epigenetic regulatory protein MeCP2 determine its binding specificity. Biochemistry 2014; 53:3379-91. [PMID: 24828757 PMCID: PMC4045320 DOI: 10.1021/bi500424z] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/08/2014] [Indexed: 02/04/2023]
Abstract
The protein MeCP2 mediates epigenetic regulation by binding methyl-CpG (mCpG) sites on chromatin. MeCP2 consists of six domains of which one, the methyl binding domain (MBD), binds mCpG sites in duplex DNA. We show that solution conditions with physiological or greater salt concentrations or the presence of nonspecific competitor DNA is necessary for the MBD to discriminate mCpG from CpG with high specificity. The specificity for mCpG over CpG is >100-fold under these solution conditions. In contrast, the MBD does not discriminate hydroxymethyl-CpG from CpG. The MBD is unusual among site-specific DNA binding proteins in that (i) specificity is not conferred by the enhanced affinity for the specific site but rather by suppression of its affinity for generic DNA, (ii) its specific binding to mCpG is highly electrostatic, and (iii) it takes up as well as displaces monovalent cations upon DNA binding. The MBD displays an unusually high affinity for single-stranded DNA independent of modification or sequence. In addition, the MBD forms a discrete dimer on DNA via a noncooperative binding pathway. Because the affinity of the second monomer is 1 order of magnitude greater than that of nonspecific binding, the MBD dimer is a unique molecular complex. The significance of these results in the context of neuronal function and development and MeCP2-related developmental disorders such as Rett syndrome is discussed.
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Affiliation(s)
- Sergei Khrapunov
- Department of Biochemistry and Department of
Genetics, Albert Einstein College of Medicine
of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United
States
| | - Christopher Warren
- Department of Biochemistry and Department of
Genetics, Albert Einstein College of Medicine
of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United
States
| | - Huiyong Cheng
- Department of Biochemistry and Department of
Genetics, Albert Einstein College of Medicine
of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United
States
| | - Esther
R. Berko
- Department of Biochemistry and Department of
Genetics, Albert Einstein College of Medicine
of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United
States
| | - John M. Greally
- Department of Biochemistry and Department of
Genetics, Albert Einstein College of Medicine
of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United
States
| | - Michael Brenowitz
- Department of Biochemistry and Department of
Genetics, Albert Einstein College of Medicine
of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United
States
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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.
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25
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Abstract
The role of epigenetics in human disease has become an area of increased research interest. Collaborative efforts from scientists and clinicians have led to a better understanding of the molecular mechanisms by which epigenetic regulation is involved in the pathogenesis of many human diseases. Several neurological and non-neurological disorders are associated with mutations in genes that encode for epigenetic factors. One of the most studied proteins that impacts human disease and is associated with deregulation of epigenetic processes is Methyl CpG binding protein 2 (MeCP2). MeCP2 is an epigenetic regulator that modulates gene expression by translating epigenetic DNA methylation marks into appropriate cellular responses. In order to highlight the importance of epigenetics to development and disease, we will discuss how MeCP2 emerges as a key epigenetic player in human neurodevelopmental, neurological, and non-neurological disorders. We will review our current knowledge on MeCP2-related diseases, including Rett Syndrome, Angelman Syndrome, Fetal Alcohol Spectrum Disorder, Hirschsprung disease, and Cancer. Additionally, we will briefly discuss about the existing MeCP2 animal models that have been generated for a better understanding of how MeCP2 impacts certain human diseases.
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Affiliation(s)
| | - Mojgan Rastegar
- Author to whom correspondence should be addressed; ; Tel.: +204-272-3108; Fax: +204-789-3900
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