GTBP, a 160-Kilodalton Protein Essential for Mismatch-binding Activity in Human Cells

Palombo, Fabio; Gallinari, Paola; Iaccarino, Ingram; Lettieri, Teresa; Hughes, Melya J.; D’Arrigo, Antonello; Truong, Oanh; Hsuan, J. Justin; Jiricny, Josef

doi:10.1126/science.7604265

Cited by 483 publications

(313 citation statements)

References 26 publications

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“…This conclusion gained support from transfection experiments we performed with SA 3T3 cells whose resistance to MNNG could be overcome by ectopic overexpression of MSH2. Since MMR also corrects spontaneously occurring G-T mismatches arising, for example, from deamination of 5-methylcytosine in DNA, 28 one might expect ES cells to show a lower spontaneous mutation frequency than somatic cells. This has indeed been found to be the case.…”

Section: Discussionmentioning

confidence: 99%

Mouse embryonic stem cells are hypersensitive to apoptosis triggered by the DNA damage O6-methylguanine due to high E2F1 regulated mismatch repair

Roos¹,

Christmann²,

Fraser

et al. 2007

Cell Death Differ

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Exposure of stem cells to genotoxins may lead to embryonic lethality or teratogenic effects. This can be prevented by efficient DNA repair or by eliminating genetically damaged cells. Using undifferentiated mouse embryonic stem (ES) cells as a pluripotent model system, we compared ES cells with differentiated cells, with regard to apoptosis induction by alkylating agents forming the highly mutagenic and killing DNA adduct O 6 -methylguanine. Upon treatment with N-methyl-N 0 -nitro-N-nitrosoguanidine (MNNG), ES cells undergo apoptosis at much higher frequency than differentiated cells, although they express a high level of the repair protein O 6 -methylguanine-DNA methyltransferase (MGMT). Apoptosis induced by MNNG is due to O 6 -methylguanine DNA adducts, since inhibition of MGMT sensitized ES cells. The high sensitivity of ES cells to O 6 -methylating agents is due to high expression of the mismatch repair proteins MSH2 and MSH6 (MutSa), which declines during differentiation. High MutSa expression in ES cells was related to a high hyperphosphorylated retinoblastoma (ppRb) level and E2F1 activity that upregulates MSH2, causing, in turn, stabilization of MSH6. Non-repaired O 6 -methylguanine adducts were shown to cause DNA doublestranded breaks, stabilization of p53 and upregulation of Fas/CD95/Apo-1 at significantly higher level in ES cells than in fibroblasts. The high apoptotic response of ES cells to O 6 -methylguanine adducts may contribute to reduction of the mutational load in the progenitor population.

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Section: Discussionmentioning

confidence: 99%

Mouse embryonic stem cells are hypersensitive to apoptosis triggered by the DNA damage O6-methylguanine due to high E2F1 regulated mismatch repair

Roos¹,

Christmann²,

Fraser

et al. 2007

Cell Death Differ

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“…BR140 shows similarity to a group of transcriptional coactivators, including the TAF250 subunit of TFIID 38 . MSH6 is mammalian MutS homolog essential for DNA mismatch repair 51 , which contains a PWWP domain at its extreme N-terminus. However, msh6 orthologs in S. cerevisiae, C. elegans and A. thaliana do not contain this domain.…”

Section: Coordinatesmentioning

confidence: 99%

The PWWP domain of mammalian DNA methyltransferase Dnmt3b defines a new family of DNA-binding folds

et al. 2002

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The PWWP domain is a weakly conserved sequence motif found in >60 eukaryotic proteins, including the mammalian DNA methyltransferases Dnmt3a and Dnmt3b. These proteins often contain other chromatin-association domains. A 135-residue PWWP domain from mouse Dnmt3b (amino acids 223-357) has been structurally characterized at 1.8 Å resolution. The N-terminal half of this domain resembles a barrel-like five-stranded structure, whereas the C-terminal half contains a five-helix bundle. The two halves are packed against each other to form a single structural module that exhibits a prominent positive electrostatic potential. The PWWP domain alone binds DNA in vitro, probably through its basic surface. We also show that recombinant Dnmt3b2 protein (a splice variant of Dnmt3b) and two N-terminal deletion mutants (Δ218 and Δ369) have approximately equal methyl transfer activity on unmethylated and hemimethylated CpG-containing oligonucleotides. The Δ218 protein, which includes the PWWP domain, binds DNA more strongly than Δ369, which lacks the PWWP domain.Genomic patterns of cytosine methylation at the C5 position play key roles in the organization and control of mammalian chromatin (reviewed in refs 1-3). Mammalian DNA methyltransferases (MTases) all contain a C-terminal catalytic region that is structurally and functionally homologous to bacterial MTases. The eukaryotic DNA MTases have been grouped into three families based on (i) distinctive properties of their N-terminal regions and (ii) intriguing differences in DNA substrate preferences. The first eukaryotic DNA MTase, Dnmt1, contains a large N-terminal regulatory region of ~1,000 amino acids and shows a preference for hemimethylated DNA in vitro [4][5][6] . Dnmt2, a relatively small protein, contains only the MTase domain, and its function is still unclear 7 . Recombinant Dnmt3 acts on unmethylated and hemimethylated DNA at equal rates in vitro 8,9 .The task of dissecting the functional roles of the N-terminal region of the different MTase families is just beginning. These regions vary widely in size and are probably responsible for the diverse biological functions of eukaryotic DNA MTases. These functions include the © 2002 Nature Publishing Group Correspondence should be addressed to X.C. xcheng@emory.edu. Competing interests statementThe authors declare that they have no competing financial interests. HHS Public Access Dnmt3 contains a PWWP domainThe sequences of Dnmt3 orthologs have been determined from human and mouse. They all contain an N-terminal variable region (~280 amino acids in Dnmt3a and ~220 amino acids in Dnmt3b), followed by three stretches of conserved regions: the PWWP motif, six repeats of a CXXC motif and a set of 10 motifs conserved among DNA MTase catalytic regions (Fig. 1a). The PWWP motif 28 was first identified in a gene family related to the hepatomaderived growth factor (HDGF) 29 and WHSC1 genes (Wolf-Hirschhorn Syndrome Candidate) 30 . The corresponding sequence in Dnmt3 is SWWP (Fig. 1b); only the last two positions of the motif...

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“…In recent years, the human homologues of the bacterial MMR enzymes have been discovered. To date, eight such genes have been identi®fed in humans, MLH1 (Bronner et al, 1994;Han et al, 1995), MSH2 Fishel et al, 1993;Peltomaki et al, 1993), MSH3 (Fujii and Shimada, 1989;Watanabe et al, 1996), MSH4 (PaquisFlucklinger et al, 1997), MSH5 (Edelmann et al, 1999;Her and Doggett, 1998), MSH6 (Drummond et al, 1995;Palombo et al, 1995;Papadopoulos et al, 1995), PMS1 (Horii et al, 1994;Nicolaides et al, 1994) and PMS2 (Narayanan et al, 1997;Nicolaides et al, 1994), but their mechanisms of action have not yet been fully elucidated. In humans MMR de®ciency was initially associated with the hereditary syndrome HNPCC (Hereditary Non-Polyposis Colorectal Cancer) (de la Chapelle and Peltomaki, 1995), a relatively common genetic condition that a ects 1 : 200 people.…”

Section: Introductionmentioning

confidence: 99%

DNA methylator and mismatch repair phenotypes are not mutually exclusive in colorectal cancer cell lines

et al. 2000

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A potential link between DNA repair and de novo methylation of exogenous sequences in colorectal cancer cell lines suggested that cells de®cient in mismatch repair (MMR 7 ) had an increased ability to silence the introduced virus promoter by DNA methylation due to the presence of a methylator phenotype (MET + ) (Lengauer et al., 1997a). We explored this relationship in more detail and found that although there was a clear di erence in the abilities of MMR + cells to express the viral promoter compared to their MMR 7 counterparts, this di erence was not consistently explained by levels of methylation in the viral promoter. Furthermore, we were unable to distinguish di erences between the levels of methylation of six endogenous known CpG islands or 100 random DNA fragments containing CCGG sites within the cells. No consistent di erences between the abilities of the cells to methylate the CpG island in exon 2 of the p16 gene were observed after transient demethylation by 5-aza-2'-deoxycytidine nor in the levels of expression of three human methyltransferase enzymes. Our results do not therefore support the existence of mutually exclusive DNA methylation (MET) and DNA repair (MMR) phenotypes. Oncogene (2000) 19, 943 ± 952.

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GTBP, a 160-Kilodalton Protein Essential for Mismatch-binding Activity in Human Cells

Cited by 483 publications

References 26 publications

Mouse embryonic stem cells are hypersensitive to apoptosis triggered by the DNA damage O6-methylguanine due to high E2F1 regulated mismatch repair

Mouse embryonic stem cells are hypersensitive to apoptosis triggered by the DNA damage O6-methylguanine due to high E2F1 regulated mismatch repair

The PWWP domain of mammalian DNA methyltransferase Dnmt3b defines a new family of DNA-binding folds

DNA methylator and mismatch repair phenotypes are not mutually exclusive in colorectal cancer cell lines

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