scholarly journals The Polymerase η Translesion Synthesis DNA Polymerase Acts Independently of the Mismatch Repair System To Limit Mutagenesis Caused by 7,8-Dihydro-8-Oxoguanine in Yeast

2009 ◽  
Vol 29 (19) ◽  
pp. 5316-5326 ◽  
Author(s):  
Sarah V. Mudrak ◽  
Caroline Welz-Voegele ◽  
Sue Jinks-Robertson
Keyword(s):  
Dna Replication ◽  
Mismatch Repair ◽  
Dna Polymerase ◽  
Translesion Synthesis ◽  
Nuclear Antigen ◽  
Repair System ◽  
New Paradigm ◽  
Mismatch Repair System ◽  
Mutation Assay ◽  
Proliferating Cell

ABSTRACT Reactive oxygen species are ubiquitous mutagens that have been linked to both disease and aging. The most studied oxidative lesion is 7,8-dihydro-8-oxoguanine (GO), which is often miscoded during DNA replication, resulting specifically in GC → TA transversions. In yeast, the mismatch repair (MMR) system repairs GO·A mismatches generated during DNA replication, and the polymerase η (Polη) translesion synthesis DNA polymerase additionally promotes error-free bypass of GO lesions. It has been suggested that Polη limits GO-associated mutagenesis exclusively through its participation in the filling of MMR-generated gaps that contain GO lesions. In the experiments reported here, the SUP4-o forward-mutation assay was used to monitor GC → TA mutation rates in strains defective in MMR (Msh2 or Msh6) and/or in Polη activity. The results clearly demonstrate that Polη can function independently of the MMR system to prevent GO-associated mutations, presumably through preferential insertion of cytosine opposite replication-blocking GO lesions. Furthermore, the Polη-dependent bypass of GO lesions is more efficient on the lagging strand of replication and requires an interaction with proliferating cell nuclear antigen. These studies establish a new paradigm for the prevention of GO-associated mutagenesis in eukaryotes.

scholarly journals Phosphorylation of PCNA by EGFR inhibits mismatch repair and promotes misincorporation during DNA synthesis

2015 ◽  
Vol 112 (18) ◽  
pp. 5667-5672 ◽  
Author(s):  
Janice Ortega ◽  
Jessie Y. Li ◽  
Sanghee Lee ◽  
Dan Tong ◽  
Liya Gu ◽  
...  
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Mismatch Repair ◽  
Posttranslational Modifications ◽  
Growth Factor Receptor ◽  
Nuclear Antigen ◽  
Dna Mismatch ◽  
Epidermal Growth ◽  
Mismatch Recognition ◽  
Proliferating Cell

Proliferating cell nuclear antigen (PCNA) plays essential roles in eukaryotic cells during DNA replication, DNA mismatch repair (MMR), and other events at the replication fork. Earlier studies show that PCNA is regulated by posttranslational modifications, including phosphorylation of tyrosine 211 (Y211) by the epidermal growth factor receptor (EGFR). However, the functional significance of Y211-phosphorylated PCNA remains unknown. Here, we show that PCNA phosphorylation by EGFR alters its interaction with mismatch-recognition proteins MutSα and MutSβ and interferes with PCNA-dependent activation of MutLα endonuclease, thereby inhibiting MMR at the initiation step. Evidence is also provided that Y211-phosphorylated PCNA induces nucleotide misincorporation during DNA synthesis. These findings reveal a novel mechanism by which Y211-phosphorylated PCNA promotes cancer development and progression via facilitating error-prone DNA replication and suppressing the MMR function.

Fibroblast proliferation during myocardial development in rats is regulated by IGF-1 receptors

1995 ◽  
Vol 269 (3) ◽  
pp. H943-H951 ◽  
Author(s):  
K. Reiss ◽  
W. Cheng ◽  
J. Kajstura ◽  
E. H. Sonnenblick ◽  
L. G. Meggs ◽  
...  
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Proliferating Cell Nuclear Antigen ◽  
Cardiac Fibroblasts ◽  
Nuclear Antigen ◽  
Dna Polymerase Alpha ◽  
Myocardial Development ◽  
Left And Right ◽  
Proliferating Cell

To determine whether the growth of cardiac fibroblasts during development is modulated by the insulin-like growth factor (IGF)-1 receptor (IGF-1R), the expression of IGF-1, IGF-2, and IGF-1R was determined in fibroblasts from fetal and postnatal hearts. The expression of proliferating cell nuclear antigen (PCNA) and DNA polymerase-alpha was also evaluated in combination with the estimation of DNA replication. In comparison with fetal hearts, at postnatal day 21, fibroblast expression of IGF-1R mRNA, IGF-2, PCNA, and DNA polymerase-alpha was reduced by 77, 70, 80, and 86%, respectively. Moreover, IGF-1R protein decreased by 48% at 21 days. Bromodeoxyuridine labeling decreased by 88 and 89% in the left and right ventricle, respectively, at this time. Two different antisense oligodeoxynucleotides to IGF-1R reduced DNA replication by 60 and 44% in fibroblasts in culture. In addition, this intervention markedly attenuated the growth response of fibroblasts to IGF-1 or serum. In conclusion, the IGF-1R system appears to play a major role in the regulation of fibroblast growth in the heart in vivo.

scholarly journals Slipped Misalignment Mechanisms of Deletion Formation: In Vivo Susceptibility to Nucleases

1999 ◽  
Vol 181 (2) ◽  
pp. 477-482 ◽  
Author(s):  
Malgorzata Bzymek ◽  
Catherine J. Saveson ◽  
Vladimir V. Feschenko ◽  
Susan T. Lovett
Keyword(s):  
Mismatch Repair ◽  
Dna Polymerase ◽  
Repeated Sequences ◽  
Repair System ◽  
Dna Polymerase Iii ◽  
Exonuclease I ◽  
Polymerase Iii ◽  
Mismatch Repair System ◽  
Genetic Rearrangements

ABSTRACT Misalignment of repeated sequences during DNA replication can lead to deletions or duplications in genomic DNA. In Escherichia coli, such genetic rearrangements can occur at high frequencies, independent of the RecA-homologous recombination protein, and are sometimes associated with sister chromosome exchange (SCE). Two mechanisms for RecA-independent genetic rearrangements have been proposed: simple replication misalignment of the nascent strand and its template and SCE-associated misalignment involving both nascent strands. We examined the influence of the 3′ exonuclease of DNA polymerase III and exonuclease I on deletion via these mechanisms in vivo. Because mutations in these exonucleases stimulate tandem repeat deletion, we conclude that displaced 3′ ends are a common intermediate in both mechanisms of slipped misalignments. Our results also confirm the notion that two distinct mechanisms contribute to slipped misalignments: simple replication misalignment events are sensitive to DNA polymerase III exonuclease, whereas SCE-associated events are sensitive to exonuclease I. If heterologies are present between repeated sequences, the mismatch repair system dependent on MutS and MutH aborts potential deletion events via both mechanisms. Our results suggest that simple slipped misalignment and SCE-associated misalignment intermediates are similarly susceptible to destruction by the mismatch repair system.

scholarly journals Hypermutability of homonucleotide runs in mismatch repair and DNA polymerase proofreading yeast mutants.

1997 ◽  
Vol 17 (5) ◽  
pp. 2859-2865 ◽  
Author(s):  
H T Tran ◽  
J D Keen ◽  
M Kricker ◽  
M A Resnick ◽  
D A Gordenin
Keyword(s):  
Mismatch Repair ◽  
Dna Polymerase ◽  
Repair System ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Changes ◽  
Coding Sequences ◽  
Frameshift Mutations ◽  
Dna Polymerase Epsilon ◽  
Mismatch Repair System ◽  
Repair Defect

Homonucleotide runs in coding sequences are hot spots for frameshift mutations and potential sources of genetic changes leading to cancer in humans having a mismatch repair defect. We examined frameshift mutations in homonucleotide runs of deoxyadenosines ranging from 4 to 14 bases at the same position in the LYS2 gene of the yeast Saccharomyces cerevisiae. In the msh2 mismatch repair mutant, runs of 9 to 14 deoxyadenosines are 1,700-fold to 51,000-fold, respectively, more mutable for single-nucleotide deletions than are runs of 4 deoxyadenosines. These frameshift mutations can account for up to 99% of all forward mutations inactivating the 4-kb LYS2 gene. Based on results with single and double mutations of the POL2 and MSH2 genes, both DNA polymerase epsilon proofreading and mismatch repair are efficient for short runs while only the mismatch repair system prevents frameshift mutations in runs of > or = 8 nucleotides. Therefore, coding sequences containing long homonucleotide runs are likely to be at risk for mutational inactivation in cells lacking mismatch repair capability.

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