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Pandey S, Pruitt K. Functional assessment of MeCP2 in Rett syndrome and cancers of breast, colon, and prostate. Biochem Cell Biol 2017; 95:368-378. [DOI: 10.1139/bcb-2016-0154] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ever since the first report that mutations in methyl-CpG-binding protein 2 (MeCP2) causes Rett syndrome (RTT), a severe neurological disorder in females world-wide, there has been a keen interest to gain a comprehensive understanding of this protein. While the classical model associated with MeCP2 function suggests its role in gene suppression via recruitment of co-repressor complexes and histone deacetylases to methylated CpG-sites, recent discoveries have brought to light its role in transcription activation, modulation of RNA splicing, and chromatin compaction. Various post-translational modifications (PTMs) of MeCP2 further increase its functional versatility. Involvement of MeCP2 in pathologies other than RTT, such as tumorigenesis however, remains poorly explored and understood. This review provides a survey of the literature implicating MeCP2 in breast, colon and prostate cancer.
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Affiliation(s)
- Somnath Pandey
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
| | - Kevin Pruitt
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
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Hashimoto Y, Zumwalt TJ, Goel A. DNA methylation patterns as noninvasive biomarkers and targets of epigenetic therapies in colorectal cancer. Epigenomics 2016; 8:685-703. [PMID: 27102979 DOI: 10.2217/epi-2015-0013] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Aberrant DNA methylation is frequently detected in gastrointestinal tumors, and can therefore potentially be used to screen, diagnose, prognosticate, and predict colorectal cancers (CRCs). Although colonoscopic screening remains the gold standard for CRC screening, this procedure is invasive, expensive, and suffers from poor patient compliance. Methylated DNA is an attractive choice for a biomarker substrate because CRCs harbor hundreds of aberrantly methylated genes. Furthermore, abundance in extracellular environments and resistance to degradation and enrichment in serum, stool, and other noninvasive bodily fluids, allows quantitative measurements of methylated DNA biomarkers. This article describes the most important studies that investigated the efficacy of serum- or stool-derived methylated DNA as population-based screening biomarkers in CRC, details several mechanisms and factors that control DNA methylation, describes a better use of prevailing technologies that discover novel DNA methylation biomarkers, and illustrates the diversity of demethylating agents and their applicability toward clinical impact.
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Affiliation(s)
- Yutaka Hashimoto
- Center for Translational Genomics & Oncology, Baylor Scott & White Research Institute & Sammons Cancer Center, Baylor University Medical Center, Dallas, TX, USA
| | - Timothy J Zumwalt
- Center for Translational Genomics & Oncology, Baylor Scott & White Research Institute & Sammons Cancer Center, Baylor University Medical Center, Dallas, TX, USA
| | - Ajay Goel
- Center for Translational Genomics & Oncology, Baylor Scott & White Research Institute & Sammons Cancer Center, Baylor University Medical Center, Dallas, TX, USA
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Abstract
The methyl-CpG binding proteins (MBPs) interpret the methylation of DNA and its components. The number of MBPs in the human body currently stands at 15, which are split into 3 branches, a reflection of the intricate mechanisms of gene regulation. Each branch utilizes a different mechanism for interacting with methylated DNA or its components. These interactions function to direct gene expression and maintain or alter DNA architecture. It is these functions that are commonly exploited in human disease. For this review, we will focus on each protein and any roles it may have in initiating, promoting, progressing, or inhibiting cancer. This will highlight common threads in the roles of these proteins, which will allow us to speculate on potentially productive directions for future research.
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Affiliation(s)
- Lee Parry
- School of Biosciences, Cardiff University, Cardiff, UK
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Hite KC, Adams VH, Hansen JC. Recent advances in MeCP2 structure and function. Biochem Cell Biol 2009; 87:219-27. [PMID: 19234536 DOI: 10.1139/o08-115] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in methyl DNA binding protein 2 (MeCP2) cause the neurodevelopmental disorder Rett syndrome (RTT). The mechanism(s) by which the native MeCP2 protein operates in the cell are not well understood. Historically, MeCP2 has been characterized as a proximal gene silencer with 2 functional domains: a methyl DNA binding domain and a transcription repression domain. However, several lines of new data indicate that MeCP2 structure and function relationships are more complex. In this review, we first discuss recent studies that have advanced understanding of the basic structural biochemistry of MeCP2. This is followed by an analysis of cell-based experiments suggesting MeCP2 is a regulator, rather than a strict silencer, of transcription. The new data establish MeCP2 as a multifunctional nuclear protein, with potentially important roles in chromatin architecture, regulation of RNA splicing, and active transcription. We conclude by discussing clinical correlations between domain-specific mutations and RTT pathology to stress that all structural domains of MeCP2 are required to properly mediate cellular function of the intact protein.
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Affiliation(s)
- Kristopher C Hite
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA.
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Henry I, Forlani S, Vaillant S, Muschler J, Choulika A, Nicolas JF. [LagoZ and LagZ, 2 genes depleted of CpG dinucleotides, derived from the LacZ gene for the study of epigenetic control]. COMPTES RENDUS DE L'ACADEMIE DES SCIENCES. SERIE III, SCIENCES DE LA VIE 1999; 322:1061-70. [PMID: 10656146 DOI: 10.1016/s0764-4469(99)00105-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The methylation of 5'CpG 3' dinucleotides within genes creates potential targets for protein complexes that bind to methylated DNA sequences and to histone deacetylases (MBD-HDAC). This can lead to transcriptional repression by modification of chromatic. To test the importance of this repression in vivo and to determine when during development these epigenetic controls are placed on genes, two novel genes have been engineered by directed mutagenesis of the CpG-rich LacZ gene that are depleted of (LagZ) or completely lacking (LagoZ) CpG sequences. We report that the expression (transcriptional and translational) of the three genes is indistinguishable in transient assays in cleaving mouse embryos. Therefore, the complete absence of CpG sequences within three kilobases of coding sequence is compatible with its maintenance in the nucleus and with its expression. These molecules can now be used to study the ontogenesis of the CpG-dependent repressive system in intact organisms.
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Affiliation(s)
- I Henry
- Unité de biologie moléculaire du développement, Institut Pasteur, Paris, France
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Volpe P, Iacovacci P, Butler RH, Eremenko T. 5-Methylcytosine in genes with methylation-dependent regulation. FEBS Lett 1993; 329:233-7. [PMID: 8365464 DOI: 10.1016/0014-5793(93)80228-m] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An asymmetric distribution of deoxy-5-methylcytidylic acid-inhibiting restriction sites (dcm-sites) takes place in ten human genes regulated by 5-methylcytosine. These genes are dcm-site enriched upstream and dcm-site poor downstream. Along them, there is a scattering of hypermethylatable introns and hypomethylatable exons with a common code: the 5mCpG dinucleotides characterize promoters; Gp5mCs characterize introns; Tp5mCs and Cp5mCs are in small concentrations in exons. Housekeeping genes contain more dcm-sites when compared with tissue-specific genes. This depends on the higher number of dcm-sites in their promoters and introns. In exons, the relatively lower number of dcm-sites is almost the same in both housekeeping and tissue-specific genes. Going from 5' to 3', the average frequency of occurrence of these sites per nucleotide units decreases in introns and increases in exons. This difference is highly discriminated for tissue-specific and less discriminated for housekeeping genes.
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Affiliation(s)
- P Volpe
- Department of Biology, University of Rome Tor Vergata, Italy
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Bruce J, Schwartz ML, Shneidman PS, Schlaepfer WW. Methylation and expression of neurofilament genes in tissues and in cell lines of the mouse. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1993; 17:269-78. [PMID: 8510499 DOI: 10.1016/0169-328x(93)90011-d] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The light (NF-L), mid-sized (NF-M) and heavy (NF-H) neurofilament (NF) genes were probed with methylation-sensitive restriction enzymes and patterns of methylation and expression of the NF genes were compared in tissues and cell lines of the mouse. The 5' regions of all three NF genes are identified as CpG islands that remain unmethylated in expressing and non-expressing tissues, although partial methylation occurs at -795 in NF-H and at -525 in NF-M. Methylation of the NF CpG islands is associated with the inactivation of NF genes in L cells and with the selective inactivation of NF-L and NF-M in Neuro 2a cells. We also show that methylation diminishes the ability of the NF promoters to drive transcription of a CAT reporter gene. Hence, the presence of CpG islands may be important in determining patterns of NF transcription in vitro. Moreover, the preservation of CpG islands may be an evolutionary link that bears upon the nature of the NF genes and the mechanisms that have evolved to limit NF expression.
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Affiliation(s)
- J Bruce
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical School, Philadelphia 19104-6079
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Cooper GE, Khattar NH, Bishop PL, Turker MS. At least two distinct epigenetic mechanisms are correlated with high-frequency "switching" for APRT phenotypic expression in mouse embryonal carcinoma stem cells. SOMATIC CELL AND MOLECULAR GENETICS 1992; 18:215-25. [PMID: 1496418 DOI: 10.1007/bf01233858] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A series of clones displaying high frequency "switching" phenotypes for expression of the adenine phosphoribosyltransferase (aprt) gene were previously isolated from the P19 mouse embryonal carcinoma stem cell line. Most clones contained only one aprt allele. We report here the characterization of each of these clones with regards to enzymatic activity, mRNA steady state levels, DNA methylation, and chromatin conformation. When clones were selected for resistance to the purine analog 2,6-diaminopurine, which requires markedly reduced levels of APRT enzymatic activity, two distinct classes were observed. The first class was associated with reduced or undetectable levels of aprt mRNA, hypermethylation of the 5' CpG island, and a closed chromatin conformation within this region. When clones of this class were selected for reacquisition of APRT enzymatic activity they were found to have increased mRNA levels, a hypomethylated CpG island, and an open chromatin conformation. In contrast, the second class of clones displayed wild-type levels of mRNA, CpG island hypomethylation, and an open chromatin conformation regardless of whether they were selected for the presence or absence of APRT enzymatic activity. The implications of these results for general mechanisms of epigenetic change in somatic cells and the possibility that expression of the mouse aprt gene may be developmentally regulated are discussed.
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Affiliation(s)
- G E Cooper
- Department of Microbiology & Immunology, University of Kentucky College of Medicine, Lexington 40536
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Kelleher JE, Daniel AS, Murray NE. Mutations that confer de novo activity upon a maintenance methyltransferase. J Mol Biol 1991; 221:431-40. [PMID: 1833555 DOI: 10.1016/0022-2836(91)80064-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DNA methyltransferases are not only sequence specific in their action, but they also differentiate between the alternative methylation states of a target site. Some methyltransferases are equally active on either unmethylated or hemimethylated DNA and consequently function as de novo methyltransferases. Others are specific for hemimethylated target sequences, consistent with the postulated role of a maintenance methyltransferase in perpetuating a pattern of DNA modification. The molecular basis for the difference between de novo and maintenance methyltransferase activity is unknown, yet fundamental to cellular activities that are affected by different methylation states of the genome. The methyltransferase activity of the type I restriction and modification system, EcoK, is the only known prokaryotic methyltransferase shown to be specific for hemimethylated target sequences. We have isolated mutants of Escherichia coli K-12 which are able to modify unmethylated target sequences efficiently in a manner indicative of de novo methyltransferase activity. Consistent with this change in specificity, some mutations shift the balance between DNA restriction and modification as if both activities now compete at unmethylated targets. Two genes encode the methyltransferase and all the mutations are loosely clustered within one of them.
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Affiliation(s)
- J E Kelleher
- Institute of Cell and Molecular Biology, University of Edinburgh, U.K
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Abstract
Cytosine methylation is associated with gene-silencing mechanisms in a number of eukaryotic organisms. Recent studies directed at the involvement of methylation in promoter inactivation, X-chromosome and duplicate sequence inactivation and in chromatin structure changes, are presented.
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Affiliation(s)
- P S Chomet
- Plant Biology Department, University of California Berkeley 94720
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Abstract
Methylated cytosine (m5C) in DNA appears to be an important modulator of the expression of some genes. There are several lines of evidence that gradual loss of m5C is relevant to in vitro cellular ageing: m5C loss occurs during cell culture; m5C loss is detectable at an early stage of culture; m5C loss appears to be related to cell division not just duration in culture; the rate of m5C loss appears to be related to in vitro lifespan of the cell strain in question; and the total loss of m5C during an in vitro lifespan is significant by comparison with induced-changes in m5C levels which effect cell growth, or cause cell-death in culture. Progressive loss of m5C in dividing cells may thus produce the multi-step cell division "clock" which underlies the Hayflick phenomenon.
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Affiliation(s)
- J Catania
- Department of Geriatric Medicine, University of Manchester, U.K
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Au KY, Yao CM, Cowan R, Ng SF. Programming of the macronucleus of Paramecium during asexual and sexual reproduction: A further study with cytidine analogues, dimethylsulfoxide, L-ethionine and N-butyric acid. Eur J Protistol 1990. [DOI: 10.1016/s0932-4739(11)80386-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Phillips RL, Kaeppler SM, Peschke VM. Do We Understand Somaclonal Variation? PROGRESS IN PLANT CELLULAR AND MOLECULAR BIOLOGY 1990. [DOI: 10.1007/978-94-009-2103-0_19] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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