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Abstract
The base excision repair system is vital to the repair of endogenous and exogenous DNA damage. This pathway is initiated by one of several DNA glycosylases that recognizes and excises specific DNA lesions in a coordinated fashion. Methyl-CpG Domain Protein 4 (MBD4) and Thymine DNA Glycosylase (TDG) are the two major G:T glycosylases that remove thymine generated by the deamination of 5-methylcytosine. Both of these glycosylases also remove a variety of other base lesions, including G:U and preferentially act at CpG sites throughout the genome. Many have questioned the purpose of seemingly redundant glycosylases, but new information has emerged to suggest MBD4 and TDG have diverse biological functions. MBD4 has been closely linked to apoptosis, while TDG has been clearly implicated in transcriptional regulation. This article reviews all of these developments, and discusses the consequences of germline and somatic mutations that lead to non-synonymous amino acid substitutions on MBD4 and TDG protein function. In addition, we report the finding of alternatively spliced variants of MBD4 and TDG and the results of functional studies of a tumor-associated variant of MBD4.
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da Costa NM, Hautefeuille A, Cros MP, Melendez ME, Waters T, Swann P, Hainaut P, Pinto LFR. Transcriptional regulation of thymine DNA glycosylase (TDG) by the tumor suppressor protein p53. Cell Cycle 2012; 11:4570-8. [PMID: 23165212 DOI: 10.4161/cc.22843] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Thymine DNA glycosylase (TDG) belongs to the superfamily of uracil DNA glycosylases (UDG) and is the first enzyme in the base-excision repair pathway (BER) that removes thymine from G:T mismatches at CpG sites. This glycosylase activity has also been found to be critical for active demethylation of genes involved in embryonic development. Here we show that wild-type p53 transcriptionally regulates TDG expression. Chromatin immunoprecipitation (ChIP) and luciferase assays indicate that wild-type p53 binds to a domain of TDG promoter containing two p53 consensus response elements (p53RE) and activates its transcription. Next, we have used a panel of cell lines with different p53 status to demonstrate that TDG mRNA and protein expression levels are induced in a p53-dependent manner under different conditions. This panel includes isogenic breast and colorectal cancer cell lines with wild-type or inactive p53, esophageal squamous cell carcinoma cell lines lacking p53 or expressing a temperature-sensitive p53 mutant and normal human bronchial epithelial cells. Induction of TDG mRNA expression is accompanied by accumulation of TDG protein in both nucleus and cytoplasm, with nuclear re-localization occurring upon DNA damage in p53-competent, but not -incompetent, cells. These observations suggest a role for p53 activity in TDG nuclear translocation. Overall, our results show that TDG expression is directly regulated by p53, suggesting that loss of p53 function may affect processes mediated by TDG, thus negatively impacting on genetic and epigenetic stability.
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53
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Thomson JP, Lempiäinen H, Hackett JA, Nestor CE, Müller A, Bolognani F, Oakeley EJ, Schübeler D, Terranova R, Reinhardt D, Moggs JG, Meehan RR. Non-genotoxic carcinogen exposure induces defined changes in the 5-hydroxymethylome. Genome Biol 2012; 13:R93. [PMID: 23034186 PMCID: PMC3491421 DOI: 10.1186/gb-2012-13-10-r93] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 10/03/2012] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Induction and promotion of liver cancer by exposure to non-genotoxic carcinogens coincides with epigenetic perturbations, including specific changes in DNA methylation. Here we investigate the genome-wide dynamics of 5-hydroxymethylcytosine (5hmC) as a likely intermediate of 5-methylcytosine (5mC) demethylation in a DNA methylation reprogramming pathway. We use a rodent model of non-genotoxic carcinogen exposure using the drug phenobarbital. RESULTS Exposure to phenobarbital results in dynamic and reciprocal changes to the 5mC/5hmC patterns over the promoter regions of a cohort of genes that are transcriptionally upregulated. This reprogramming of 5mC/5hmC coincides with characteristic changes in the histone marks H3K4me2, H3K27me3 and H3K36me3. Quantitative analysis of phenobarbital-induced genes that are involved in xenobiotic metabolism reveals that both DNA modifications are lost at the transcription start site, while there is a reciprocal relationship between increasing levels of 5hmC and loss of 5mC at regions immediately adjacent to core promoters. CONCLUSIONS Collectively, these experiments support the hypothesis that 5hmC is a potential intermediate in a demethylation pathway and reveal precise perturbations of the mouse liver DNA methylome and hydroxymethylome upon exposure to a rodent hepatocarcinogen.
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54
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Murphy KC, Volkert MR. Structural/functional analysis of the human OXR1 protein: identification of exon 8 as the anti-oxidant encoding function. BMC Mol Biol 2012; 13:26. [PMID: 22873401 PMCID: PMC3462732 DOI: 10.1186/1471-2199-13-26] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 07/24/2012] [Indexed: 12/27/2022] Open
Abstract
Background The human OXR1 gene belongs to a class of genes with conserved functions that protect cells from reactive oxygen species (ROS). The gene was found using a screen of a human cDNA library by its ability to suppress the spontaneous mutator phenotype of an E. coli mutH nth strain. The function of OXR1 is unknown. The human and yeast genes are induced by oxidative stress and targeted to the mitochondria; the yeast gene is required for resistance to hydrogen peroxide. Multiple spliced isoforms are expressed in a variety of human tissues, including brain. Results In this report, we use a papillation assay that measures spontaneous mutagenesis of an E. coli mutM mutY strain, a host defective for oxidative DNA repair. Papillation frequencies with this strain are dependent upon a G→T transversion in the lacZ gene (a mutation known to occur as a result of oxidative damage) and are suppressed by in vivo expression of human OXR1. N-terminal, C-terminal and internal deletions of the OXR1 gene were constructed and tested for suppression of the mutagenic phenotype of the mutM mutY strain. We find that the TLDc domain, encoded by the final four exons of the OXR1 gene, is not required for papillation suppression in E. coli. Instead, we show that the protein segment encoded by exon 8 of OXR1 is responsible for the suppression of oxidative damage in E. coli. Conclusion The protein segment encoded by OXR1 exon 8 plays an important role in the anti-oxidative function of the human OXR1 protein. This result suggests that the TLDc domain, found in OXR1 exons 12–16 and common in many proteins with nuclear function, has an alternate (undefined) role other than oxidative repair.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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Kamileri I, Karakasilioti I, Garinis GA. Nucleotide excision repair: new tricks with old bricks. Trends Genet 2012; 28:566-73. [PMID: 22824526 DOI: 10.1016/j.tig.2012.06.004] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/05/2012] [Accepted: 06/19/2012] [Indexed: 12/22/2022]
Abstract
Nucleotide excision repair (NER) is a major DNA repair pathway that ensures that the genome remains functionally intact and is faithfully transmitted to progeny. However, defects in NER lead, in addition to cancer and aging, to developmental abnormalities whose clinical heterogeneity and varying severity cannot be fully explained by the DNA repair deficiencies. Recent work has revealed that proteins in NER play distinct roles, including some that go well beyond DNA repair. NER factors are components of protein complexes known to be involved in nucleosome remodeling, histone ubiquitination, and transcriptional activation of genes involved in nuclear receptor signaling, stem cell reprogramming, and postnatal mammalian growth. Together, these findings add new pieces to the puzzle for understanding NER and the relevance of NER defects in development and disease.
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Affiliation(s)
- Irene Kamileri
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013, Heraklion, Crete, Greece
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56
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Swartzlander DB, Bauer NC, Corbett AH, Doetsch PW. Regulation of base excision repair in eukaryotes by dynamic localization strategies. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 110:93-121. [PMID: 22749144 DOI: 10.1016/b978-0-12-387665-2.00005-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This chapter discusses base excision repair (BER) and the known mechanisms defined thus far regulating BER in eukaryotes. Unlike the situation with nucleotide excision repair and double-strand break repair, little is known about how BER is regulated to allow for efficient and accurate repair of many types of DNA base damage in both nuclear and mitochondrial genomes. Regulation of BER has been proposed to occur at multiple, different levels including transcription, posttranslational modification, protein-protein interactions, and protein localization; however, none of these regulatory mechanisms characterized thus far affect a large spectrum of BER proteins. This chapter discusses a recently discovered mode of BER regulation defined in budding yeast cells that involves mobilization of DNA repair proteins to DNA-containing organelles in response to genotoxic stress.
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Affiliation(s)
- Daniel B Swartzlander
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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Rüegg J, Cai W, Karimi M, Kiss NB, Swedenborg E, Larsson C, Ekström TJ, Pongratz I. Epigenetic regulation of glucose transporter 4 by estrogen receptor β. Mol Endocrinol 2011; 25:2017-28. [PMID: 22016564 DOI: 10.1210/me.2011-1054] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Glucose transporter 4 (Glut4) is an important regulator of cellular glucose uptake in adipose tissue and skeletal muscle. The estrogen receptors α and β (ERα and ERβ) have been shown to regulate Glut4. However, the regulatory mechanisms are unclear, and there are conflicting results about the effects of the two ER isoforms on Glut4 activity. In this study we investigated how the lack of either ER isoform affects Glut4 expression in differentiated mouse embryonic fibroblasts. Our results demonstrate that Glut4 transcription is markedly reduced in cells lacking ERβ, both basally and upon induction by liver X receptor. These changes in Glut4 expression could not be explained by the lack of ERβ as ligand-activated transcription factor. They were rather brought about by hypermethylation of one single CpG in the Glut4 promoter in the ERβ-deficient cells. This CpG is part of an Sp1-binding site, and Sp1 binding was reduced by its methylation. Treatment with Sp1 inhibitor diminished Glut4 expression in wild-type, but not in ERβ-deficient cells, suggesting that reduced recruitment of Sp1 to the Glut4 promoter is responsible for the differences in Glut4 expression. Reintroduction of ERβ into ERβ-deficient cells partly restored Glut4 transcription and stabilized low DNA methylation after treatment with the DNA demethylating agent 5-Aza-2'-deoxycytidine. Our findings demonstrate the involvement of DNA methylation in Glut4 regulation and imply a novel function for ERβ in mediating epigenetic events and thereby regulating gene expression.
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Affiliation(s)
- Joëlle Rüegg
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, 141 57 Sweden.
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58
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Cortellino S, Xu J, Sannai M, Moore R, Caretti E, Cigliano A, Le Coz M, Devarajan K, Wessels A, Soprano D, Abramowitz LK, Bartolomei MS, Rambow F, Bassi MR, Bruno T, Fanciulli M, Renner C, Klein-Szanto AJ, Matsumoto Y, Kobi D, Davidson I, Alberti C, Larue L, Bellacosa A. Thymine DNA glycosylase is essential for active DNA demethylation by linked deamination-base excision repair. Cell 2011; 146:67-79. [PMID: 21722948 DOI: 10.1016/j.cell.2011.06.020] [Citation(s) in RCA: 595] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/17/2011] [Accepted: 06/12/2011] [Indexed: 01/19/2023]
Abstract
DNA methylation is a major epigenetic mechanism for gene silencing. Whereas methyltransferases mediate cytosine methylation, it is less clear how unmethylated regions in mammalian genomes are protected from de novo methylation and whether an active demethylating activity is involved. Here, we show that either knockout or catalytic inactivation of the DNA repair enzyme thymine DNA glycosylase (TDG) leads to embryonic lethality in mice. TDG is necessary for recruiting p300 to retinoic acid (RA)-regulated promoters, protection of CpG islands from hypermethylation, and active demethylation of tissue-specific developmentally and hormonally regulated promoters and enhancers. TDG interacts with the deaminase AID and the damage response protein GADD45a. These findings highlight a dual role for TDG in promoting proper epigenetic states during development and suggest a two-step mechanism for DNA demethylation in mammals, whereby 5-methylcytosine and 5-hydroxymethylcytosine are first deaminated by AID to thymine and 5-hydroxymethyluracil, respectively, followed by TDG-mediated thymine and 5-hydroxymethyluracil excision repair.
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Affiliation(s)
- Salvatore Cortellino
- Cancer Biology Program and Epigenetics and Progenitor Cells Keystone Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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59
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Schultz-Norton JR, Ziegler YS, Nardulli AM. ERα-associated protein networks. Trends Endocrinol Metab 2011; 22:124-9. [PMID: 21371903 DOI: 10.1016/j.tem.2010.11.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Revised: 11/30/2010] [Accepted: 11/30/2010] [Indexed: 11/21/2022]
Abstract
Estrogen receptor α (ERα) is a ligand-activated transcription factor that, upon binding hormone, interacts with specific recognition sequences in DNA. An extensive body of literature has documented the association of individual regulatory proteins with ERα. It has recently become apparent that, instead of simply recruiting individual proteins, ERα recruits interconnected networks of proteins with discrete activities that play crucial roles in maintaining the structure and function of the receptor, stabilizing the receptor-DNA interaction, influencing estrogen-responsive gene expression, and repairing misfolded proteins and damaged DNA. Together these studies suggest that the DNA-bound ERα serves as a nucleating factor for the recruitment of protein complexes involved in key processes including the oxidative stress response, DNA repair, and transcription regulation.
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Affiliation(s)
- Jennifer R Schultz-Norton
- Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, 407 South Goodwin Avenue, Urbana, IL 61801, USA
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60
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Smet-Nocca C, Wieruszeski JM, Léger H, Eilebrecht S, Benecke A. SUMO-1 regulates the conformational dynamics of thymine-DNA Glycosylase regulatory domain and competes with its DNA binding activity. BMC BIOCHEMISTRY 2011; 12:4. [PMID: 21284855 PMCID: PMC3040724 DOI: 10.1186/1471-2091-12-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 02/01/2011] [Indexed: 12/01/2022]
Abstract
Background The human thymine-DNA glycosylase (TDG) plays a dual role in base excision repair of G:U/T mismatches and in transcription. Regulation of TDG activity by SUMO-1 conjugation was shown to act on both functions. Furthermore, TDG can interact with SUMO-1 in a non-covalent manner. Results Using NMR spectroscopy we have determined distinct conformational changes in TDG upon either covalent sumoylation on lysine 330 or intermolecular SUMO-1 binding through a unique SUMO-binding motif (SBM) localized in the C-terminal region of TDG. The non-covalent SUMO-1 binding induces a conformational change of the TDG amino-terminal regulatory domain (RD). Such conformational dynamics do not exist with covalent SUMO-1 attachment and could potentially play a broader role in the regulation of TDG functions for instance during transcription. Both covalent and non-covalent processes activate TDG G:U repair similarly. Surprisingly, despite a dissociation of the SBM/SUMO-1 complex in presence of a DNA substrate, SUMO-1 preserves its ability to stimulate TDG activity indicating that the non-covalent interactions are not directly involved in the regulation of TDG activity. SUMO-1 instead acts, as demonstrated here, indirectly by competing with the regulatory domain of TDG for DNA binding. Conclusions SUMO-1 increases the enzymatic turnover of TDG by overcoming the product-inhibition of TDG on apurinic sites. The mechanism involves a competitive DNA binding activity of SUMO-1 towards the regulatory domain of TDG. This mechanism might be a general feature of SUMO-1 regulation of other DNA-bound factors such as transcription regulatory proteins.
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Affiliation(s)
- Caroline Smet-Nocca
- Institut de Recherche Interdisciplinaire, Université de Lille1 - Université de Lille2 - CNRS USR3078, Parc de la Haute Borne, 50 avenue de Halley, 59658 Villeneuve d'Ascq, France
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61
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Cortázar D, Kunz C, Selfridge J, Lettieri T, Saito Y, MacDougall E, Wirz A, Schuermann D, Jacobs AL, Siegrist F, Steinacher R, Jiricny J, Bird A, Schär P. Embryonic lethal phenotype reveals a function of TDG in maintaining epigenetic stability. Nature 2011; 470:419-23. [PMID: 21278727 DOI: 10.1038/nature09672] [Citation(s) in RCA: 286] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 11/17/2010] [Indexed: 12/18/2022]
Abstract
Thymine DNA glycosylase (TDG) is a member of the uracil DNA glycosylase (UDG) superfamily of DNA repair enzymes. Owing to its ability to excise thymine when mispaired with guanine, it was proposed to act against the mutability of 5-methylcytosine (5-mC) deamination in mammalian DNA. However, TDG was also found to interact with transcription factors, histone acetyltransferases and de novo DNA methyltransferases, and it has been associated with DNA demethylation in gene promoters following activation of transcription, altogether implicating an engagement in gene regulation rather than DNA repair. Here we use a mouse genetic approach to determine the biological function of this multifaceted DNA repair enzyme. We find that, unlike other DNA glycosylases, TDG is essential for embryonic development, and that this phenotype is associated with epigenetic aberrations affecting the expression of developmental genes. Fibroblasts derived from Tdg null embryos (mouse embryonic fibroblasts, MEFs) show impaired gene regulation, coincident with imbalanced histone modification and CpG methylation at promoters of affected genes. TDG associates with the promoters of such genes both in fibroblasts and in embryonic stem cells (ESCs), but epigenetic aberrations only appear upon cell lineage commitment. We show that TDG contributes to the maintenance of active and bivalent chromatin throughout cell differentiation, facilitating a proper assembly of chromatin-modifying complexes and initiating base excision repair to counter aberrant de novo methylation. We thus conclude that TDG-dependent DNA repair has evolved to provide epigenetic stability in lineage committed cells.
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Affiliation(s)
- Daniel Cortázar
- Department of Biomedicine, Institute of Biochemistry and Genetics, University of Basel, 4048 Basel, Switzerland
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Schär P, Fritsch O. DNA repair and the control of DNA methylation. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2011; 67:51-68. [PMID: 21141724 DOI: 10.1007/978-3-7643-8989-5_3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The successful establishment and stable maintenance of cell identity are critical for organismal development and tissue homeostasis. Cell identity is provided by epigenetic mechanisms that facilitate a selective readout of the genome. Operating at the level of chromatin, they establish defined gene expression programs during cell differentiation. Among the epigenetic modifications in mammalian chromatin, the 5'-methylation of cytosine in CpG dinucleotides is unique in that it affects the DNA rather than histones and the biochemistry of the DNA methylating enzymes offers a mechanistic explanation for stable inheritance. Yet, DNA methylation states appear to be more dynamic and their maintenance more complex than existing models predict. Also, methylation patterns are by far not always faithfully inherited, as best exemplified by human cancers. Often, these show widespread hypo- or hypermethylation across their genomes, reflecting an underlying epigenetic instability that may have contributed to carcinogenesis. The phenotype of unstable methylation in cancer illustrates the importance of quality control in the DNA methylation system and implies the existence of proof-reading mechanisms that enforce fidelity to DNA methylation in healthy tissue. Fidelity seems particularly important in islands of unmethylated CpG-rich sequences where an accurate maintenance of un- or differentially methylated states is critical for stable expression of nearby genes. Methylation proof-reading in such sequences requires a system capable of recognition and active demethylation of erroneously methylated CpGs. Active demethylation of 5-methylcytosine has been known to occur for long, but the underlying mechanisms have remained enigmatic and controversial. However, recent progress in this direction substantiates a role of DNA repair in such processes. This review will address general aspects of cytosine methylation stability in mammalian DNA and explore a putative role of DNA repair in methylation control.
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Affiliation(s)
- Primo Schär
- Institute of Biochemistry and Genetics, Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland.
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63
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Morgan MT, Maiti A, Fitzgerald ME, Drohat AC. Stoichiometry and affinity for thymine DNA glycosylase binding to specific and nonspecific DNA. Nucleic Acids Res 2010; 39:2319-29. [PMID: 21097883 PMCID: PMC3064789 DOI: 10.1093/nar/gkq1164] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Deamination of 5-methylcytosine to thymine creates mutagenic G·T mispairs, contributing to cancer and genetic disease. Thymine DNA glycosylase (TDG) removes thymine from these G·T lesions, and follow-on base excision repair yields a G·C pair. A previous crystal structure revealed TDG (catalytic domain) bound to abasic DNA product in a 2:1 complex, one subunit at the abasic site and the other bound to undamaged DNA. Biochemical studies showed TDG can bind abasic DNA with 1:1 or 2:1 stoichiometry, but the dissociation constants were unknown, as was the stoichiometry and affinity for binding substrates and undamaged DNA. We showed that 2:1 binding is dispensable for G·U activity, but its role in G·T repair was unknown. Using equilibrium binding anisotropy experiments, we show that a single TDG subunit binds very tightly to G·U mispairs and abasic (G·AP) sites, and somewhat less tightly G·T mispairs. Kinetics experiments show 1:1 binding provides full G·T activity. TDG binds undamaged CpG sites with remarkable affinity, modestly weaker than G·T mispairs, and exhibits substantial affinity for nonspecific DNA. While 2:1 binding is observed for large excess TDG concentrations, our findings indicate that a single TDG subunit is fully capable of locating and processing G·U or G·T lesions.
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Affiliation(s)
- Michael T Morgan
- Department of Biochemistry and Molecular Biology and Greenebaum Cancer Center, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
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64
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Smet-Nocca C, Wieruszeski JM, Melnyk O, Benecke A. NMR-based detection of acetylation sites in peptides. J Pept Sci 2010; 16:414-23. [PMID: 20572211 DOI: 10.1002/psc.1257] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Acetylation of histone tails as well as non-histone proteins was found to be a major component of the 'chromatin code' that regulates transcription through the recruitment of transcription factors, co-regulators and DNA-binding proteins. Acetylation can have several effects modifying protein-protein interactions, protein activity, localization and stability. Using NMR spectroscopy, we provide a simple way to detect acetyl moieties at the epsilon-amino function of lysine residues based on peptides derived from Histone H4 and TDG amino-terminal domains. Significant changes of acetyl-lysine resonances as compared to non-acetylated residues allow a direct identification of specific acetylated lysine. We also show that, in unfolded peptides, acetylation of lysine side chains leads to characteristic NMR signals that vary only weakly depending on the primary sequence or the total number of acetylated sites, indicating that the acetamide group does not establish any interactions with other residues. Furthermore, resonance changes upon acetylation are restricted to residues nearby the acetylation site, indicating that acetylation does not modify the overall peptide conformation.
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Affiliation(s)
- Caroline Smet-Nocca
- Institut de Recherche Interdisciplinaire, CNRS USR3078, Université de Lille1, Parc de la Haute Borne, 50 Avenue de Halley, 59658 Villeneuve d'Ascq Cedex, France.
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Abstract
DNA methylation is one of the best-characterized epigenetic modifications and has been implicated in numerous biological processes, including transposable element silencing, genomic imprinting and X chromosome inactivation. Compared with other epigenetic modifications, DNA methylation is thought to be relatively stable. Despite its role in long-term silencing, DNA methylation is more dynamic than originally thought as active DNA demethylation has been observed during specific stages of development. In the past decade, many enzymes have been proposed to carry out active DNA demethylation and growing evidence suggests that, depending on the context, this process may be achieved by multiple mechanisms. Insight into how DNA methylation is dynamically regulated will broaden our understanding of epigenetic regulation and have great implications in somatic cell reprogramming and regenerative medicine.
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Shimizu Y, Uchimura Y, Dohmae N, Saitoh H, Hanaoka F, Sugasawa K. Stimulation of DNA Glycosylase Activities by XPC Protein Complex: Roles of Protein-Protein Interactions. J Nucleic Acids 2010; 2010. [PMID: 20798892 PMCID: PMC2925305 DOI: 10.4061/2010/805698] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 06/09/2010] [Indexed: 11/20/2022] Open
Abstract
We showed that XPC complex, which is a DNA damage detector for nucleotide excision repair, stimulates activity of thymine DNA glycosylase (TDG) that initiates base excision repair. XPC appeared to facilitate the enzymatic turnover of TDG by promoting displacement from its own product abasic site, although the precise mechanism underlying this stimulation has not been clarified. Here we show that XPC has only marginal effects on the activity of E. coli TDG homolog (EcMUG), which remains bound to the abasic site like human TDG but does not significantly interacts with XPC. On the contrary, XPC significantly stimulates the activities of sumoylated TDG and SMUG1, both of which exhibit quite different enzymatic kinetics from unmodified TDG but interact with XPC. These results point to importance of physical interactions for stimulation of DNA glycosylases by XPC and have implications in the molecular mechanisms underlying mutagenesis and carcinogenesis in XP-C patients.
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Affiliation(s)
- Yuichiro Shimizu
- Cellular Physiology Laboratory, RIKEN Discovery Research Institute, Wako, Saitama 351-0198, Japan
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Smet-Nocca C, Wieruszeski JM, Chaar V, Leroy A, Benecke A. The thymine-DNA glycosylase regulatory domain: residual structure and DNA binding. Biochemistry 2010; 47:6519-30. [PMID: 18512959 DOI: 10.1021/bi7022283] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thymine-DNA glycosylases (TDGs) initiate base excision repair by debasification of the erroneous thymine or uracil nucleotide in G.T and G.U mispairs which arise at high frequency through spontaneous or enzymatic deamination of methylcytosine and cytosine, respectively. Human TDG has furthermore been shown to have a functional role in transcription and epigenetic regulation through the interaction with transcription factors from the nuclear receptor superfamily, transcriptional coregulators, and a DNA methyltransferase. The TDG N-terminus encodes regulatory functions, as it assures both G.T versus G.U specificity and contains the sites for interaction and posttranslational modification by transcription-related activities. While the molecular function of the evolutionarily conserved central catalytic domain of TDG in base excision repair has been elucidated by determination of its three-dimensional structure, the mechanisms by which the N-terminus exerts its regulatory roles, as well as the function of TDG in transcription regulation, remain to be understood. We describe here the residual structure of the TDG N-terminus in both contexts of the isolated domain and the entire protein. These studies lead to the characterization of a small structural domain in the TDG N-terminal region preceding the catalytic core and coinciding with the region of functional regulation of TDG's activities. This regulatory domain exhibits a small degree of organization and is implicated in dynamic molecular interactions with the catalytic domain and nonselective interactions with double-stranded DNA, providing a molecular explanation for the evolutionarily acquired G.T mismatch processing activity of TDG.
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Affiliation(s)
- Caroline Smet-Nocca
- Institut de Recherche Interdisciplinaire, USR CNRS 3078, Université de Lille 1, 1 rue du Professeur Calmette, 59021 Lille Cedex, France
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LSD1-mediated demethylation of histone H3 lysine 4 triggers Myc-induced transcription. Oncogene 2010; 29:3691-702. [PMID: 20418916 DOI: 10.1038/onc.2010.120] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Myc is a transcription factor that significantly contributes to cancer progression by modulating the expression of important genes through binding to a DNA sequence, CACGTG, called E-box. We find that on Myc binding to chromatin, the lysine-demethylating enzyme, LSD1, triggers a transient demethylation of lysine 4 in the histone H3. In addition, we demonstrate that Myc binds and recruits LSD1 to the E-box chromatin and the formation of this complex is stimulated by cAMP-PKA. Demethylation by LSD1 produces H(2)O(2), which locally oxidizes guanine and induces the recruitment of 8-oxoguanine-DNA glycosylase (OGG1) and of the nuclease Ape1 on the E-box chromatin. Inhibition of oxidation or silencing of LSD1, OGG1 or Ape1 significantly reduce transcription and inhibit mRNA accumulation of Myc-target genes. Collectively, these data highlight the role of transient LSD1-mediated demethylation of H3K4 leading to local DNA oxidation as driving force in the assembly of the Myc-induced transcription initiation complex.
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69
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Liu XP, Li CP, Hou JL, Liu YF, Liang RB, Liu JH. Expression and characterization of thymine-DNA glycosylase from Aeropyrum pernix. Protein Expr Purif 2010; 70:1-6. [DOI: 10.1016/j.pep.2009.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 10/04/2009] [Accepted: 10/06/2009] [Indexed: 10/20/2022]
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70
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Mohan RD, Litchfield DW, Torchia J, Tini M. Opposing regulatory roles of phosphorylation and acetylation in DNA mispair processing by thymine DNA glycosylase. Nucleic Acids Res 2009; 38:1135-48. [PMID: 19966277 PMCID: PMC2831317 DOI: 10.1093/nar/gkp1097] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
CpG dinucleotides are mutational hotspots associated with cancer and genetic diseases. Thymine DNA glycosylase (TDG) plays an integral role in CpG maintenance by excising mispaired thymine and uracil in a CpG context and also participates in transcriptional regulation via gene-specific CpG demethylation and functional interactions with the transcription machinery. Here, we report that protein kinase C α (PKCα) interacts with TDG and phosphorylates amino-terminal serine residues adjacent to lysines acetylated by CREB-binding protein (CBP) and p300 (CBP/p300). We establish that acetylation and phosphorylation are mutually exclusive, and their interplay dramatically alters the DNA mispair-processing functions of TDG. Remarkably, acetylation of the amino-terminal region abrogates high-affinity DNA binding and selectively prevents processing of G:T mispairs. In contrast, phosphorylation does not markedly alter DNA interactions, but may preserve G:T processing in vivo by preventing CBP-mediated acetylation. Mutational analysis suggests that the acetyl-acceptor lysines are not directly involved in contacting DNA, but may constitute a conformationally sensitive interface that modulates DNA interactions. These findings reveal opposing roles of CBP/p300 and PKCα in regulating the DNA repair functions of TDG and suggest that the interplay of these modifications in vivo may be critically important in the maintenance of CpG dinucleotides and epigenetic regulation.
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Affiliation(s)
- Ryan D Mohan
- Department of Physiology and Pharmacology, Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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71
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The interaction between thymine DNA glycosylase and nuclear receptor coactivator 3 is required for the transcriptional activation of nuclear hormone receptors. Mol Cell Biochem 2009; 333:221-32. [DOI: 10.1007/s11010-009-0223-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 06/25/2009] [Indexed: 10/20/2022]
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72
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Interaction of the replication proteins and the capsid protein of porcine circovirus type 1 and 2 with host proteins. Virology 2009; 386:122-31. [DOI: 10.1016/j.virol.2008.12.039] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 12/02/2008] [Accepted: 12/26/2008] [Indexed: 01/08/2023]
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73
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Finsterbusch T, Mankertz A. Porcine circoviruses--small but powerful. Virus Res 2009; 143:177-83. [PMID: 19647885 DOI: 10.1016/j.virusres.2009.02.009] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 02/15/2009] [Indexed: 01/31/2023]
Abstract
When porcine circovirus type 1 (PCV1) was isolated more than 40 years ago as a non-pathogenic contaminant of a porcine kidney cell line, enthusiasm and curiosity kept within reasonable limits. Virologists became more interested, when a second variant was isolated and termed PCV2, because PCV2 is linked to postweaning multisystemic wasting disease (PMWS), a new emerging multifactorial disease in swine. Both PCV1 and PCV2 are small and rather simply organized and express only few proteins. Therefore, it was expected that the factor(s) triggering PMWS should be easily identified, but more than one decade of PCV research has not yet singled out a molecule inducing the disease onset. Unravelling the molecular features of PCV and the channels through which the virus interacts with its host are key to manage, prevent and treat PMWS and other PCV-associated diseases. Since we have learned many aspects of the molecular biology of PCV in the last years, it is time for a résumé!
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Affiliation(s)
- Tim Finsterbusch
- Division of Viral Infections (FG12), Robert Koch-Institute, 13353 Berlin, Germany
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74
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Gehring M, Reik W, Henikoff S. DNA demethylation by DNA repair. Trends Genet 2009; 25:82-90. [PMID: 19144439 DOI: 10.1016/j.tig.2008.12.001] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 01/16/2023]
Abstract
Active DNA demethylation underlies key facets of reproduction in flowering plants and mammals and serves a general genome housekeeping function in plants. A family of 5-methylcytosine DNA glycosylases catalyzes plant demethylation via the well-known DNA base-excision-repair process. Although the existence of active demethylation has been known for a longer time in mammals, the means of achieving it remain murky and mammals lack counterparts to the plant demethylases. Several intriguing experiments have indicated, but not conclusively proven, that DNA repair is also a plausible mechanism for animal demethylation. Here, we examine what is known from flowering plants about the pathways and function of enzymatic demethylation and discuss possible mechanisms whereby DNA repair might also underlie global demethylation in mammals.
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Affiliation(s)
- Mary Gehring
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, Seattle, WA 98109, USA
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75
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Le Page Y, Menuet A, Kah O, Pakdel F. Characterization of a cis-acting element involved in cell-specific expression of the zebrafish brain aromatase gene. Mol Reprod Dev 2008; 75:1549-57. [PMID: 18288647 DOI: 10.1002/mrd.20892] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The cytochrome P450 Aromatase is the key enzyme catalyzing the conversion of androgens into estrogens. In zebrafish, the brain aromatase is encoded by cyp19b. Expression of cyp19b is restricted to radial glial cells bordering forebrain ventricles and is strongly stimulated by estrogens during development. At the promoter level, we have previously shown that an estrogen responsive element (ERE) is required for induction by estrogens. Here, we investigated the role of ERE flanking regions in the control of cell-specific expression. First, we show that a 20 bp length motif, named G x RE (glial x responsive element), acts in synergy with the ERE to mediate the estrogenic induction specifically in glial cells. Second, we demonstrate that, in vitro, this sequence binds factors exclusively present in glial or neuro-glial cells and is able to confer a glial specificity to an artificial estrogen-dependent gene. Taken together, these results contribute to the understanding of the molecular mechanisms allowing cyp19b regulation by estrogens and allowed to identify a promoter sequence involved in the strong estrogen inducibility of cyp19b which is specific for glial cells. The exceptional aromatase activity measured in the brain of teleost fish could rely on such mechanisms.
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Affiliation(s)
- Yann Le Page
- Université de Rennes 1, UMR CNRS 6026, Interactions Cellulaires et Moléculaires, Rennes, France
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76
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Kim EJ, Um SJ. Thymine–DNA glycosylase interacts with and functions as a coactivator of p53 family proteins. Biochem Biophys Res Commun 2008; 377:838-42. [DOI: 10.1016/j.bbrc.2008.10.058] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2008] [Accepted: 10/15/2008] [Indexed: 10/21/2022]
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77
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Active DNA demethylation and DNA repair. Differentiation 2008; 77:1-11. [PMID: 19281759 DOI: 10.1016/j.diff.2008.09.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 06/19/2008] [Accepted: 07/07/2008] [Indexed: 12/17/2022]
Abstract
DNA methylation on cytosine is an epigenetic modification and is essential for gene regulation and genome stability in vertebrates. Traditionally DNA methylation was considered as the most stable of all heritable epigenetic marks. However, it has become clear that DNA methylation is reversible by enzymatic "active" DNA demethylation, with examples in plant cells, animal development and immune cells. It emerges that "pruning" of methylated cytosines by active DNA demethylation is an important determinant for the DNA methylation signature of a cell. Work in plants and animals shows that demethylation occurs by base excision and nucleotide excision repair. Far from merely protecting genomic integrity from environmental insult, DNA repair is therefore at the heart of an epigenetic activation process.
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78
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Zhou J, Blue EK, Hu G, Herring BP. Thymine DNA glycosylase represses myocardin-induced smooth muscle cell differentiation by competing with serum response factor for myocardin binding. J Biol Chem 2008; 283:35383-92. [PMID: 18945672 DOI: 10.1074/jbc.m805489200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myocardin is a serum response factor (SRF) co-activator that regulates transcription of many smooth muscle-specific genes and is essential for development of vascular smooth muscle. We used a yeast two-hybrid screen, with myocardin as bait in a search for factors that regulate myocardin transcriptional activity. From this screen, thymine DNA glycosylase (TDG) was identified as a myocardin-associated protein. TDG was originally identified as an enzyme involved in base excision repair of T:G mismatches caused by spontaneous deamination of methylated cytosines. However, TDG has also been shown to act as a transcriptional co-activator or co-repressor. The interaction between TDG and myocardin was confirmed in vitro by glutathione S-transferase pull down and in vivo by co-immunoprecipitation assays. We found that TDG abrogates myocardin induced expression of smooth muscle-specific genes and represses the trans-activation of the promoters of myocardin of these genes. Overexpression of TDG in SMCs down-regulated smooth muscle marker expression. Conversely, depletion of endogenous TDG in SMCs increased smooth muscle-specific myosin heavy chain (SM MHC) and Telokin gene expression. Glutathione S-transferase pull-down assays demonstrated that TDG binds to a region of myocardin that includes the SRF binding domain. Furthermore, TDG was found to compete with SRF for binding to myocardin in vitro and in vivo, suggesting that TDG can inhibit expression of smooth muscle-specific genes, at least in part, through disrupting SRF/myocardin interactions. Finally, we demonstrated that the glycosylase activity of TDG is not required for its inhibitory effects on myocardin function. This study reveals a previously unsuspected role for the repair enzyme TDG as a repressor of smooth muscle differentiation via competing with SRF for binding to myocardin.
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Affiliation(s)
- Jiliang Zhou
- Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208, USA.
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79
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Baute J, Depicker A. Base excision repair and its role in maintaining genome stability. Crit Rev Biochem Mol Biol 2008; 43:239-76. [PMID: 18756381 DOI: 10.1080/10409230802309905] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
For all living organisms, genome stability is important, but is also under constant threat because various environmental and endogenous damaging agents can modify the structural properties of DNA bases. As a defense, organisms have developed different DNA repair pathways. Base excision repair (BER) is the predominant pathway for coping with a broad range of small lesions resulting from oxidation, alkylation, and deamination, which modify individual bases without large effect on the double helix structure. As, in mammalian cells, this damage is estimated to account daily for 10(4) events per cell, the need for BER pathways is unquestionable. The damage-specific removal is carried out by a considerable group of enzymes, designated as DNA glycosylases. Each DNA glycosylase has its unique specificity and many of them are ubiquitous in microorganisms, mammals, and plants. Here, we review the importance of the BER pathway and we focus on the different roles of DNA glycosylases in various organisms.
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Affiliation(s)
- Joke Baute
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Gent, Belgium
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80
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Boland MJ, Christman JK. Characterization of Dnmt3b:thymine-DNA glycosylase interaction and stimulation of thymine glycosylase-mediated repair by DNA methyltransferase(s) and RNA. J Mol Biol 2008; 379:492-504. [PMID: 18452947 PMCID: PMC2705441 DOI: 10.1016/j.jmb.2008.02.049] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 02/21/2008] [Accepted: 02/25/2008] [Indexed: 11/22/2022]
Abstract
Methylation of cytosine residues in CpG dinucleotides plays an important role in epigenetic regulation of gene expression and chromatin structure/stability in higher eukaryotes. DNA methylation patterns are established and maintained at CpG dinucleotides by DNA methyltransferases (Dnmt1, Dnmt3a, and Dnmt3b). In mammals and many other eukaryotes, the CpG dinucleotide is underrepresented in the genome. This loss is postulated to be the result of unrepaired deamination of cytosine and 5-methylcytosine to uracil and thymine, respectively. Two thymine glycosylases are believed to reduce the impact of 5-methylcytosine deamination. G/T mismatch-specific thymine-DNA glycosylase (Tdg) and methyl-CpG binding domain protein 4 can both excise uracil or thymine at U.G and T.G mismatches to initiate base excision repair. Here, we report the characterization of interactions between Dnmt3b and both Tdg and methyl-CpG binding domain protein 4. Our results demonstrate (1) that both Tdg and Dnmt3b are colocalized to heterochromatin and (2) reduction of T.G mismatch repair efficiency upon loss of DNA methyltransferase expression, as well as a requirement for an RNA component for correct T.G mismatch repair.
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Affiliation(s)
- Michael J. Boland
- Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE. 68198
| | - Judith K. Christman
- Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE. 68198
- The Eppley Institute for Research in Cancer & Allied Diseases, University of Nebraska Medical Center, Omaha, NE. 68198
- UNMC/Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE. 68198
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81
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Cyclical DNA methylation of a transcriptionally active promoter. Nature 2008; 452:45-50. [PMID: 18322525 DOI: 10.1038/nature06544] [Citation(s) in RCA: 646] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 12/12/2007] [Indexed: 12/12/2022]
Abstract
Processes that regulate gene transcription are directly under the influence of the genome organization. The epigenome contains additional information that is not brought by DNA sequence, and generates spatial and functional constraints that complement genetic instructions. DNA methylation on CpGs constitutes an epigenetic mark generally correlated with transcriptionally silent condensed chromatin. Replication of methylation patterns by DNA methyltransferases maintains genome stability through cell division. Here we present evidence of an unanticipated dynamic role for DNA methylation in gene regulation in human cells. Periodic, strand-specific methylation/demethylation occurs during transcriptional cycling of the pS2/TFF1 gene promoter on activation by oestrogens. DNA methyltransferases exhibit dual actions during these cycles, being involved in CpG methylation and active demethylation of 5mCpGs through deamination. Inhibition of this process precludes demethylation of the pS2 gene promoter and its subsequent transcriptional activation. Cyclical changes in the methylation status of promoter CpGs may thus represent a critical event in transcriptional achievement.
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82
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Guan X, Madabushi A, Chang DY, Fitzgerald ME, Shi G, Drohat AC, Lu AL. The human checkpoint sensor Rad9-Rad1-Hus1 interacts with and stimulates DNA repair enzyme TDG glycosylase. Nucleic Acids Res 2007; 35:6207-18. [PMID: 17855402 PMCID: PMC2094074 DOI: 10.1093/nar/gkm678] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Human (h) DNA repair enzyme thymine DNA glycosylase (hTDG) is a key DNA glycosylase in the base excision repair (BER) pathway that repairs deaminated cytosines and 5-methyl-cytosines. The cell cycle checkpoint protein Rad9–Rad1–Hus1 (the 9-1-1 complex) is the surveillance machinery involved in the preservation of genome stability. In this study, we show that hTDG interacts with hRad9, hRad1 and hHus1 as individual proteins and as a complex. The hHus1 interacting domain is mapped to residues 67–110 of hTDG, and Val74 of hTDG plays an important role in the TDG–Hus1 interaction. In contrast to the core domain of hTDG (residues 110–308), hTDG(67–308) removes U and T from U/G and T/G mispairs, respectively, with similar rates as native hTDG. Human TDG activity is significantly stimulated by hHus1, hRad1, hRad9 separately, and by the 9-1-1 complex. Interestingly, the interaction between hRad9 and hTDG, as detected by co-immunoprecipitation (Co-IP), is enhanced following N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) treatment. A significant fraction of the hTDG nuclear foci co-localize with hRad9 foci in cells treated with methylating agents. Thus, the 9-1-1 complex at the lesion sites serves as both a damage sensor to activate checkpoint control and a component of the BER.
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Affiliation(s)
| | | | | | | | | | | | - A-Lien Lu
- *To whom correspondence should be addressed. +1 410 706 4356+1 410 706 1787
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83
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Schultz-Norton JR, Walt KA, Ziegler YS, McLeod IX, Yates JR, Raetzman LT, Nardulli AM. The deoxyribonucleic acid repair protein flap endonuclease-1 modulates estrogen-responsive gene expression. Mol Endocrinol 2007; 21:1569-80. [PMID: 17488975 DOI: 10.1210/me.2006-0519] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The ligand-occupied estrogen receptor alpha (ERalpha) initiates changes in gene expression through its interaction with target DNA. The capacity of ERalpha to modulate gene expression is influenced by the association of the receptor with a variety of coregulatory proteins. To further understand the role of these coregulatory proteins in ERalpha-mediated transcription, we have isolated and identified proteins associated with ERalpha when it is bound to the consensus estrogen response element. One of the proteins identified in this complex, flap endonuclease-1 (FEN-1), is required for DNA replication and repair. We show that FEN-1 interacts directly with ERalpha and enhances the interaction of ERalpha with estrogen response element-containing DNA. More importantly, chromatin immunoprecipitation and RNA interference assays demonstrate that endogenously expressed FEN-1 associates with the native pS2 gene in MCF-7 cells and influences estrogen-responsive gene expression. Interestingly, estrogen differentially regulates expression of FEN-1 in mouse uterine epithelial, stromal, and myometrial cells. Together, our studies help to elucidate the functional consequence of the ERalpha-FEN-1 interaction and increase our understanding of the elaborate regulatory mechanisms that drive estrogen-responsive gene expression and DNA repair.
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Affiliation(s)
- Jennifer R Schultz-Norton
- Department of Molecular and Integrative Physiology, University of Illinois, Urbana, Illinois 61801, USA
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84
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The OXR domain defines a conserved family of eukaryotic oxidation resistance proteins. BMC Cell Biol 2007; 8:13. [PMID: 17391516 PMCID: PMC1847813 DOI: 10.1186/1471-2121-8-13] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 03/28/2007] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The NCOA7 gene product is an estrogen receptor associated protein that is highly similar to the human OXR1 gene product, which functions in oxidation resistance. OXR genes are conserved among all sequenced eukaryotes from yeast to humans. In this study we examine if NCOA7 has an oxidation resistance function similar to that demonstrated for OXR1. We also examine NCOA7 expression in response to oxidative stress and its subcellular localization in human cells, comparing these properties with those of OXR1. RESULTS We find that NCOA7, like OXR1 can suppress the oxidative mutator phenotype when expressed in an E. coli strain that exhibits an oxidation specific mutator phenotype. Moreover, NCOA7's oxidation resistance function requires expression of only its carboxyl-terminal domain and is similar in this regard to OXR1. We find that, in human cells, NCOA7 is constitutively expressed and is not induced by oxidative stress and appears to localize to the nucleus following estradiol stimulation. These properties of NCOA7 are in striking contrast to those of OXR1, which is induced by oxidative stress, localizes to mitochondria, and appears to be excluded, or largely absent from nuclei. CONCLUSION NCOA7 most likely arose from duplication. Like its homologue, OXR1, it is capable of reducing the DNA damaging effects of reactive oxygen species when expressed in bacteria, indicating the protein has an activity that can contribute to oxidation resistance. Unlike OXR1, it appears to localize to nuclei and interacts with the estrogen receptor. This raises the possibility that NCOA7 encodes the nuclear counterpart of the mitochondrial OXR1 protein and in mammalian cells it may reduce the oxidative by-products of estrogen metabolite-mediated DNA damage.
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85
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Mohan RD, Rao A, Gagliardi J, Tini M. SUMO-1-dependent allosteric regulation of thymine DNA glycosylase alters subnuclear localization and CBP/p300 recruitment. Mol Cell Biol 2006; 27:229-43. [PMID: 17060459 PMCID: PMC1800658 DOI: 10.1128/mcb.00323-06] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have demonstrated that the base excision repair enzyme thymine DNA glycosylase (TDG) mediates recruitment of histone acetyltransferases CREB-binding protein (CBP) and p300 to DNA, suggesting a plausible role for these factors in TDG-mediated repair. Furthermore, TDG was found to potentiate CBP/p300-dependent transcription and serve as a substrate for CBP/p300 acetylation. Here, we show that the small ubiquitin-like modifier 1 (SUMO-1) protein binding activity of TDG is essential for activation of CBP and localization to promyelocytic leukemia protein oncogenic domains (PODs). SUMO-1 binding is mediated by two distinct amino- and carboxy-terminal motifs (residues 144 to 148 and 319 to 322) that are negatively regulated by DNA binding via an amino-terminal hydrophilic region (residues 1 to 121). TDG is also posttranslationally modified by covalent conjugation of SUMO-1 (sumoylation) to lysine 341. Interestingly, we found that sumoylation of TDG blocks interaction with CBP and prevents TDG acetylation in vitro. Furthermore, sumoylation effectively abrogates intermolecular SUMO-1 binding and a sumoylation-deficient mutant accumulates in PODs, suggesting that sumoylation negatively regulates translocation to these nuclear structures. These findings suggest that TDG sumoylation promotes intramolecular interactions with amino- and carboxy-terminal SUMO-1 binding motifs that dramatically alter the biochemical properties and subcellular localization of TDG.
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Affiliation(s)
- Ryan D Mohan
- Department of Physiology and Pharmacology, Siebens-Drake Medical Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada N6G 2V4
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86
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Kress C, Thomassin H, Grange T. Active cytosine demethylation triggered by a nuclear receptor involves DNA strand breaks. Proc Natl Acad Sci U S A 2006; 103:11112-7. [PMID: 16840560 PMCID: PMC1544051 DOI: 10.1073/pnas.0601793103] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Indexed: 12/31/2022] Open
Abstract
Cytosine methylation at CpG dinucleotides contributes to the epigenetic maintenance of gene silencing. Dynamic reprogramming of DNA methylation patterns is believed to play a key role during development and differentiation in vertebrates. The mechanisms of DNA demethylation remain unclear and controversial. Here, we present a detailed characterization of the demethylation of an endogenous gene in cultured cells. This demethylation is triggered in a regulatory region by a transcriptional activator, the glucocorticoid receptor. We show that DNA demethylation is an active process, occurring independently of DNA replication, and in a distributive manner without concerted demethylation of cytosines on both strands. We demonstrate that the DNA backbone is cleaved 3' to the methyl cytidine during demethylation, and we suggest that a DNA repair pathway may therefore be involved in this demethylation.
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Affiliation(s)
- Clémence Kress
- Institut Jacques Monod du Centre National de la Recherche Scientifique, Universités Paris 6-7, Tour 43, 2, Place Jussieu, 75251 Paris Cedex 05, France
| | - Hélène Thomassin
- Institut Jacques Monod du Centre National de la Recherche Scientifique, Universités Paris 6-7, Tour 43, 2, Place Jussieu, 75251 Paris Cedex 05, France
| | - Thierry Grange
- Institut Jacques Monod du Centre National de la Recherche Scientifique, Universités Paris 6-7, Tour 43, 2, Place Jussieu, 75251 Paris Cedex 05, France
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87
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Morales-Ruiz T, Ortega-Galisteo AP, Ponferrada-Marín MI, Martínez-Macías MI, Ariza RR, Roldán-Arjona T. DEMETER and REPRESSOR OF SILENCING 1 encode 5-methylcytosine DNA glycosylases. Proc Natl Acad Sci U S A 2006; 103:6853-8. [PMID: 16624880 PMCID: PMC1458983 DOI: 10.1073/pnas.0601109103] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Indexed: 11/18/2022] Open
Abstract
Cytosine methylation is an epigenetic mark that promotes gene silencing and plays important roles in development and genome defense against transposons. Methylation patterns are established and maintained by DNA methyltransferases that catalyze transfer of a methyl group from S-adenosyl-L-methionine to cytosine bases in DNA. Erasure of cytosine methylation occurs during development, but the enzymatic basis of active demethylation remains controversial. In Arabidopsis thaliana, DEMETER (DME) activates the maternal expression of two imprinted genes silenced by methylation, and REPRESSOR OF SILENCING 1 (ROS1) is required for release of transcriptional silencing of a hypermethylated transgene. DME and ROS1 encode two closely related DNA glycosylase domain proteins, but it is unknown whether they participate directly in a DNA demethylation process or counteract silencing through an indirect effect on chromatin structure. Here we show that DME and ROS1 catalyze the release of 5-methylcytosine (5-meC) from DNA by a glycosylase/lyase mechanism. Both enzymes also remove thymine, but not uracil, mismatched to guanine. DME and ROS1 show a preference for 5-meC over thymine in the symmetric dinucleotide CpG context, where most plant DNA methylation occurs. Nevertheless, they also have significant activity on both substrates at CpApG and asymmetric sequences, which are additional methylation targets in plant genomes. These findings suggest that a function of ROS1 and DME is to initiate erasure of 5-meC through a base excision repair process and provide strong biochemical evidence for the existence of an active DNA demethylation pathway in plants.
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Affiliation(s)
| | | | | | | | - Rafael R. Ariza
- Departamento de Genética, Universidad de Córdoba, 14071 Córdoba, Spain
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88
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Abstract
Cytosine methylation is a common form of post-replicative DNA modification seen in both bacteria and eukaryotes. Modified cytosines have long been known to act as hotspots for mutations due to the high rate of spontaneous deamination of this base to thymine, resulting in a G/T mismatch. This will be fixed as a C-->T transition after replication if not repaired by the base excision repair (BER) pathway or specific repair enzymes dedicated to this purpose. This hypermutability has led to depletion of the target dinucleotide CpG outside of special CpG islands in mammals, which are normally unmethylated. We review the importance of C-->T transitions at non-island CpGs in human disease: When these occur in the germline, they are a common cause of inherited diseases such as epidermolysis bullosa and mucopolysaccharidosis, while in the soma they are frequently found in the genes for tumor suppressors such as p53 and the retinoblastoma protein, causing cancer. We also examine the specific repair enzymes involved, namely the endonuclease Vsr in Escherichia coli and two members of the uracil DNA glycosylase (UDG) superfamily in mammals, TDG and MBD4. Repair brings its own problems, since it will require remethylation of the replacement cytosine, presumably coupling repair to methylation by either the maintenance methylase Dnmt1 or a de novo enzyme such as Dnmt3a. Uncoupling of methylation from repair may be one way to remove methylation from DNA. We also look at the possible role of specific cytosine deaminases such as Aid and Apobec in accelerating deamination of methylcytosine and consequent DNA demethylation.
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Affiliation(s)
- C P Walsh
- Centre for Molecular Biosciences, School of Biomedical Sciences, University of Ulster, Northern Ireland
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89
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Lucey MJ, Chen D, Lopez-Garcia J, Hart SM, Phoenix F, Al-Jehani R, Alao JP, White R, Kindle KB, Losson R, Chambon P, Parker MG, Schär P, Heery DM, Buluwela L, Ali S. T:G mismatch-specific thymine-DNA glycosylase (TDG) as a coregulator of transcription interacts with SRC1 family members through a novel tyrosine repeat motif. Nucleic Acids Res 2005; 33:6393-404. [PMID: 16282588 PMCID: PMC1283525 DOI: 10.1093/nar/gki940] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 10/17/2005] [Accepted: 10/17/2005] [Indexed: 11/14/2022] Open
Abstract
Gene activation involves protein complexes with diverse enzymatic activities, some of which are involved in chromatin modification. We have shown previously that the base excision repair enzyme thymine DNA glycosylase (TDG) acts as a potent coactivator for estrogen receptor-alpha. To further understand how TDG acts in this context, we studied its interaction with known coactivators of nuclear receptors. We find that TDG interacts in vitro and in vivo with the p160 coactivator SRC1, with the interaction being mediated by a previously undescribed motif encoding four equally spaced tyrosine residues in TDG, each tyrosine being separated by three amino acids. This is found to interact with two motifs in SRC1 also containing tyrosine residues separated by three amino acids. Site-directed mutagenesis shows that the tyrosines encoded in these motifs are critical for the interaction. The related p160 protein TIF2 does not interact with TDG and has the altered sequence, F-X-X-X-Y, at the equivalent positions relative to SRC1. Substitution of the phenylalanines to tyrosines is sufficient to bring about interaction of TIF2 with TDG. These findings highlight a new protein-protein interaction motif based on Y-X-X-X-Y and provide new insight into the interaction of diverse proteins in coactivator complexes.
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Affiliation(s)
- Marie J. Lucey
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Dongsheng Chen
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Jorge Lopez-Garcia
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Stephen M. Hart
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Fladia Phoenix
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Rajai Al-Jehani
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - John P. Alao
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Roger White
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
| | - Karin B. Kindle
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
| | - Régine Losson
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
| | - Pierre Chambon
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
| | - Malcolm G. Parker
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
| | - Primo Schär
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - David M. Heery
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
| | - Lakjaya Buluwela
- Department of Oncology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- Institute of Reproductive and Developmental Biology, Imperial College LondonDu Cane Road, London W12 0NN, UK
- School of Pharmacy, University of Nottingham, University ParkNottingham NG7 2RD, UK
- Institut de Génétique et de Biologie Moléculaire et CellulaireBP10142, 67404 Illkirch-Cedex, France
- Institute of Molecular Cancer Research, University of ZurichAugust Forel Strasse 7, CH-8008 Zurich, Switzerland
| | - Simak Ali
- To whom correspondence should be addressed. Tel: +44 20 8383 3789; Fax: +44 20 8383 5830;
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90
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Araneda S, Pelloux S, Radicella JP, Angulo J, Kitahama K, Gysling K, Forray MI. 8-oxoguanine DNA glycosylase, but not Kin17 protein, is translocated and differentially regulated by estrogens in rat brain cells. Neuroscience 2005; 136:135-46. [PMID: 16182450 DOI: 10.1016/j.neuroscience.2005.06.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2004] [Revised: 06/17/2005] [Accepted: 06/22/2005] [Indexed: 11/24/2022]
Abstract
8-oxoguanine DNA glycosylase and Kin17 are proteins widely distributed and phylogenetically conserved in the CNS. 8-oxoguanine DNA glycosylase is a DNA repair enzyme that excises 7,8-dihydro-8-oxoguanine present in DNA damaged by oxidative stress. Kin17 protein is involved in DNA repair and illegitimate recombination in eukaryotic cells. The present study evaluates the effect of ovarian hormones on the expression of both proteins in the magnocellular paraventricular nucleus of the hypothalamus and the bed nucleus of the stria terminalis in female and male rat brains. In the paraventricular nucleus, ovariectomy induced a significant decrease in the number of 8-oxoguanine DNA glycosylase-positive nuclei as well as in their relative fluorescent intensity as compared with ovariectomized-estradiol treated and proestrous groups. Confocal microscopy observation demonstrated that oxoguanine DNA glycosylase protein is located in the Hoechst-dyed nuclei and cytoplasm in male and ovariectomized rats. Surprisingly, following estradiol administration to ovariectomized and proestrous rats, the 8-oxoguanine DNA glycosylase immunolabeling was observed in the nucleolus, the cytoplasm and the dendrites of cells, while Kin17 protein was always localized in the cell nuclei. In the bed nucleus of the stria terminalis, the number of 8-oxoguanine DNA glycosylase-positive nuclei during proestrous was significantly lower than the number obtained in males and ovariectomized rats and similar to the number of ovariectomized-estradiol-treated groups. In contrast to these observations, no significant differences were observed in the expression of kin17 protein. Our results suggest that estrogens differentially regulate the expression of 8-oxoguanine DNA glycosylase, but not that of Kin17 protein, in specific regions of the rat brain and that estradiol can translocate the 8-oxoguanine DNA glycosylase protein within nuclei and to other subcellular compartments.
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Affiliation(s)
- S Araneda
- Physiologie Intégrative, Cellulaire et Moléculaire, UMR5123 CNRS/UCB Lyon 1. Bat Raphaël Dubois, Campus La Doua, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.
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91
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Wada-Hiraike O, Yano T, Nei T, Matsumoto Y, Nagasaka K, Takizawa S, Oishi H, Arimoto T, Nakagawa S, Yasugi T, Kato S, Taketani Y. The DNA mismatch repair gene hMSH2 is a potent coactivator of oestrogen receptor alpha. Br J Cancer 2005; 92:2286-91. [PMID: 15886699 PMCID: PMC2361802 DOI: 10.1038/sj.bjc.6602614] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The DNA mismatch repair gene is a key regulator in the elimination of base–base mismatches and insertion/deletion loops (IDLs). Human MutS homologue 2 (hMSH2), originally identified as a human homologue of the bacterial MutS, is a tumour suppressor gene frequently mutated in hereditary nonpolyposis colorectal cancer. Hereditary nonpolyposis colorectal cancer is characterised by the early onset of colorectal cancer and the development of extracolonic cancers such as endometrial, ovarian, and urological cancers. Oestrogen receptor (ER) α and β are members of a nuclear receptor (NR) superfamily. Ligand-dependent transcription of ER is regulated by the p160 steroid receptor coactivator family, the thyroid hormone receptor-associated proteins/the vitamin D receptor-interacting proteins (TRAP/DRIP) mediator complex, and the TATA box-binding protein (TBP)-free TBP associated factor complex (TFTC) type histone acetyltransferase complex. Here, we report the interaction between ER α/β and hMSH2. Immunoprecipitation and glutathione-S-transferase pulldown assay revealed that ER α and hMSH2 interacted in a ligand-dependent manner, whereas ER β and hMSH2 interacted in a ligand-independent manner. Oestrogen receptor α/β bound to hMSH2 through the hMSH3/hMSH6 interaction domain of hMSH2. In a transient expression assay, hMSH2 potentiated the transactivation function of liganded ER α, but not that of ER β. These results suggest that hMSH2 may play an important role as a putative coactivator in ER α dependent gene expression.
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Affiliation(s)
- O Wada-Hiraike
- Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655, Japan.
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92
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Affiliation(s)
- J Christopher Fromme
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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93
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McCullough LD, Zeng Z, Blizzard KK, Debchoudhury I, Hurn PD. Ischemic nitric oxide and poly (ADP-ribose) polymerase-1 in cerebral ischemia: male toxicity, female protection. J Cereb Blood Flow Metab 2005; 25:502-12. [PMID: 15689952 DOI: 10.1038/sj.jcbfm.9600059] [Citation(s) in RCA: 262] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is well established that tissue damage and functional outcome after experimental or clinical stroke are shaped by biologic sex. We investigated the novel hypothesis that ischemic cell death from neuronally derived nitric oxide (NO) or poly-ADP ribose polymerase (PARP-1) activation is sexually dimorphic and that interruption of these molecular death pathways benefits only the male brain. Female neuronal nitric oxide synthase (nNOS) knockout (nNOS-/-) mice exhibited exacerbated histological injury after middle cerebral artery occlusion (MCAO) relative to wild-type (WT) females, unlike the protection observed in male nNOS-/- littermates. Similarly, treatment with the nNOS inhibitor (7-nitroindozole, 25 mg/kg) increased infarction in female C57Bl6 WT mice, but protected male mice. The mechanism for this sexually specific response is not mediated through changes in protein expression of endothelial NOS or inducible NOS, or differences in intraischemic cerebral blood flow. Unlike male PARP-1 knockouts (PARP1-/-), female PARP1-/- littermates sustained grossly increased ischemic damage relative to sex-matched WT mice. Treatment with a PARP inhibitor (PJ-34, 10 mg/kg) resulted in identical results. Loss of PARP-1 resulted in reversal of the neuroprotective activity by the female sex steroid, 17beta estradiol. These data suggest that the previously described cell death pathways involving NO and PARP ischemic neurotoxicity may be operant solely in male brain and that the integrity of nNO/PARP-1 signaling is paradoxically protective in the female.
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Affiliation(s)
- Louise D McCullough
- Department of Neurology, University of Connecticut Health Center, Farmington, Connecticut 06030-1840, USA.
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94
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Stivers JT. Response to Comment on "Uracil DNA Glycosylase Activity Is Dispensable for Immunoglobulin Class Switch". Science 2004; 306:2042; author reply 2042. [PMID: 15604391 DOI: 10.1126/science.1105225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- James T Stivers
- Department of Pharmacology, Johns Hopkins Medical School, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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95
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Choi Y, Harada JJ, Goldberg RB, Fischer RL. An invariant aspartic acid in the DNA glycosylase domain of DEMETER is necessary for transcriptional activation of the imprinted MEDEA gene. Proc Natl Acad Sci U S A 2004; 101:7481-6. [PMID: 15128940 PMCID: PMC409944 DOI: 10.1073/pnas.0402328101] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Helix-hairpin-helix DNA glycosylases are typically small proteins that initiate repair of DNA by excising damaged or mispaired bases. An invariant aspartic acid in the active site is involved in catalyzing the excision reaction. Replacement of this critical residue with an asparagine severely reduces catalytic activity but preserves enzyme stability and structure. The Arabidopsis DEMETER (DME) gene encodes a large 1,729-aa polypeptide with a 200-aa DNA glycosylase domain. DME is expressed primarily in the central cell of the female gametophyte. DME activates maternal allele expression of the imprinted MEDEA (MEA) gene in the central cell and is required for seed viability. We mutated the invariant aspartic acid at position 1304 in DME to asparagine (D1304N) to determine whether the catalytic activity of the DNA glycosylase domain is required for DME function in vivo. Transgenes expressing wild-type DME in the central cell rescue seed abortion caused by a mutation in the endogenous DME gene and activate maternal MEA:GFP transcription. However, transgenes expressing the D1304N mutant DME do not rescue seed abortion or activate maternal MEA:GFP transcription. Whereas ectopic expression of the wild-type DME polypeptide in pollen is sufficient to activate ectopic paternal MEA and MEA:GUS expression, equivalent expression of the D1304N mutant DME in pollen failed to do so. These results show that the conserved aspartic acid residue is necessary for DME to function in vivo and suggest that an active DNA glycosylase domain, normally associated with DNA repair, promotes gene transcription that is essential for gene imprinting.
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Affiliation(s)
- Yeonhee Choi
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616; and Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - John J. Harada
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616; and Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Robert B. Goldberg
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616; and Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Robert L. Fischer
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616; and Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
- To whom correspondence should be addressed. E-mail:
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