scholarly journals Reduced Levels of DNA Polymerase δ Induce Chromosome Fragile Site Instability in Yeast

2008 ◽  
Vol 28 (17) ◽  
pp. 5359-5368 ◽  
Author(s):  
Francene J. Lemoine ◽  
Natasha P. Degtyareva ◽  
Robert J. Kokoska ◽  
Thomas D. Petes
Keyword(s):  
Dna Polymerase ◽  
Cancer Biology ◽  
Molecular Mechanisms ◽  
Fragile Site ◽  
Fragile Sites ◽  
Dna Lesions ◽  
Catalytic Subunit ◽  
Dna Breaks ◽  
Dna Polymerase Δ ◽  
Double Strand Dna Breaks

ABSTRACT Specific regions of genomes (fragile sites) are hot spots for the chromosome rearrangements that are associated with many types of cancer cells. Understanding the molecular mechanisms regulating the stability of chromosome fragile sites, therefore, has important implications in cancer biology. We previously identified two chromosome fragile sites in Saccharomyces cerevisiae that were induced in response to the reduced expression of Pol1p, the catalytic subunit of DNA polymerase α. In the study presented here, we show that reduced levels of Pol3p, the catalytic subunit of DNA polymerase δ, induce instability at these same sites and lead to the generation of a variety of chromosomal aberrations. These findings demonstrate that a change in the stoichiometry of replicative DNA polymerases results in recombinogenic DNA lesions, presumably double-strand DNA breaks.

scholarly journals Global analysis of genomic instability caused by DNA replication stress in Saccharomyces cerevisiae

2016 ◽  
Vol 113 (50) ◽  
pp. E8114-E8121 ◽  
Author(s):  
Dao-Qiong Zheng ◽  
Ke Zhang ◽  
Xue-Chang Wu ◽  
Piotr A. Mieczkowski ◽  
Thomas D. Petes
Keyword(s):  
Dna Replication ◽  
Genomic Instability ◽  
Dna Polymerase ◽  
Replication Stress ◽  
Dna Lesions ◽  
Chromosome Loss ◽  
Dna Breaks ◽  
Dna Polymerase Δ ◽  
Dna Replication Stress ◽  
Low Levels

DNA replication stress (DRS)-induced genomic instability is an important factor driving cancer development. To understand the mechanisms of DRS-associated genomic instability, we measured the rates of genomic alterations throughout the genome in a yeast strain with lowered expression of the replicative DNA polymerase δ. By a genetic test, we showed that most recombinogenic DNA lesions were introduced during S or G2 phase, presumably as a consequence of broken replication forks. We observed a high rate of chromosome loss, likely reflecting a reduced capacity of the low-polymerase strains to repair double-stranded DNA breaks (DSBs). We also observed a high frequency of deletion events within tandemly repeated genes such as the ribosomal RNA genes. By whole-genome sequencing, we found that low levels of DNA polymerase δ elevated mutation rates, both single-base mutations and small insertions/deletions. Finally, we showed that cells with low levels of DNA polymerase δ tended to accumulate small promoter mutations that increased the expression of this polymerase. These deletions conferred a selective growth advantage to cells, demonstrating that DRS can be one factor driving phenotypic evolution.

scholarly journals A Dual Face of APE1 in the Maintenance of Genetic Stability in Monocytes: An Overview of the Current Status and Future Perspectives

Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 643
Author(s):  
Gabriela Betlej ◽  
Ewelina Bator ◽  
Antoni Pyrkosz ◽  
Aleksandra Kwiatkowska
Keyword(s):  
Genetic Stability ◽  
Molecular Mechanisms ◽  
Excision Repair ◽  
Biological Significance ◽  
Dna Lesions ◽  
Current Status ◽  
Dna Breaks ◽  
Antioxidant Genes ◽  
Double Strand Dna Breaks ◽  
Base Excision

Monocytes, which play a crucial role in the immune system, are characterized by an enormous sensitivity to oxidative stress. As they lack four key proteins responsible for DNA damage response (DDR) pathways, they are especially prone to reactive oxygen species (ROS) exposure leading to oxidative DNA lesions and, consequently, ROS-driven apoptosis. Although such a phenomenon is of important biological significance in the regulation of monocyte/macrophage/dendritic cells’ balance, it also a challenge for monocytic mechanisms that have to provide and maintain genetic stability of its own DNA. Interestingly, apurinic/apyrimidinic endonuclease 1 (APE1), which is one of the key proteins in two DDR mechanisms, base excision repair (BER) and non-homologous end joining (NHEJ) pathways, operates in monocytic cells, although both BER and NHEJ are impaired in these cells. Thus, on the one hand, APE1 endonucleolytic activity leads to enhanced levels of both single- and double-strand DNA breaks (SSDs and DSBs, respectively) in monocytic DNA that remain unrepaired because of the impaired BER and NHEJ. On the other hand, there is some experimental evidence suggesting that APE1 is a crucial player in monocytic genome maintenance and stability through different molecular mechanisms, including induction of cytoprotective and antioxidant genes. Here, the dual face of APE1 is discussed.

scholarly journals Increased Common Fragile Site Expression, Cell Proliferation Defects, and Apoptosis following Conditional Inactivation of Mouse Hus1 in Primary Cultured Cells

2007 ◽  
Vol 18 (3) ◽  
pp. 1044-1055 ◽  
Author(s):  
Min Zhu ◽  
Robert S. Weiss
Keyword(s):  
Cell Cycle ◽  
Cultured Cells ◽  
Chromosomal Abnormalities ◽  
Fragile Site ◽  
Loxp Site ◽  
Fragile Sites ◽  
Cell Cycle Checkpoint ◽  
Dna Breaks ◽  
Common Fragile Sites ◽  
Histone H2ax

Targeted disruption of the mouse Hus1 cell cycle checkpoint gene results in embryonic lethality and proliferative arrest in cultured cells. To investigate the essential functions of Hus1, we developed a system for the regulated inactivation of mouse Hus1 in primary fibroblasts. Inactivation of a loxP site-flanked conditional Hus1 allele by using a cre-expressing adenovirus resulted in reduced cell doubling, cell cycle alterations, and increased apoptosis. These phenotypes were associated with a significantly increased frequency of gross chromosomal abnormalities and an S-phase–specific accumulation of phosphorylated histone H2AX, an indicator of double-stranded DNA breaks. To determine whether these chromosomal abnormalities occurred randomly or at specific genomic regions, we assessed the stability of common fragile sites, chromosomal loci that are prone to breakage in cells undergoing replication stress. Hus1 was found to be essential for fragile site stability, because spontaneous chromosomal abnormalities occurred preferentially at common fragile sites upon conditional Hus1 inactivation. Although p53 levels increased after Hus1 loss, deletion of p53 failed to rescue the cell-doubling defect or increased apoptosis in conditional Hus1 knockout cells. In summary, we propose that Hus1 loss leads to chromosomal instability during DNA replication, triggering increased apoptosis and impaired proliferation through p53-independent mechanisms.

PCNA and DNA Polymerase δ Catalytic Subunit fromSchizosaccharomyces pombeDo Not Interact Directly

1997 ◽  
Vol 231 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Isabelle Tratner ◽  
Karine Piard ◽  
Muriel Grenon ◽  
Mylène Perderiset ◽  
Giuseppe Baldacci
Keyword(s):  
Dna Polymerase ◽  
Catalytic Subunit ◽  
Dna Polymerase Δ

scholarly journals DNA synthesis by Pol η promotes fragile site stability by preventing under-replicated DNA in mitosis

2013 ◽  
Vol 201 (3) ◽  
pp. 395-408 ◽  
Author(s):  
Valérie Bergoglio ◽  
Anne-Sophie Boyer ◽  
Erin Walsh ◽  
Valeria Naim ◽  
Gaëlle Legube ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Dna Sequences ◽  
Molecular Mechanisms ◽  
Fragile Site ◽  
Fragile Sites ◽  
Nuclear Bodies ◽  
Replication Checkpoint ◽  
Genome Damage ◽  
Fork Stalling ◽  
The Stability

Human DNA polymerase η (Pol η) is best known for its role in responding to UV irradiation–induced genome damage. We have recently observed that Pol η is also required for the stability of common fragile sites (CFSs), whose rearrangements are considered a driving force of oncogenesis. Here, we explored the molecular mechanisms underlying this newly identified role. We demonstrated that Pol η accumulated at CFSs upon partial replication stress and could efficiently replicate non-B DNA sequences within CFSs. Pol η deficiency led to persistence of checkpoint-blind under-replicated CFS regions in mitosis, detectable as FANCD2-associated chromosomal sites that were transmitted to daughter cells in 53BP1-shielded nuclear bodies. Expression of a catalytically inactive mutant of Pol η increased replication fork stalling and activated the replication checkpoint. These data are consistent with the requirement of Pol η–dependent DNA synthesis during S phase at replication forks stalled in CFS regions to suppress CFS instability by preventing checkpoint-blind under-replicated DNA in mitosis.

scholarly journals Interaction of the retinoblastoma protein (pRb) with the catalytic subunit of DNA polymerase δ (p125)

Oncogene ◽  
2000 ◽  
Vol 19 (48) ◽  
pp. 5464-5470 ◽  
Author(s):  
Nancy A Krucher ◽  
Adam Zygmunt ◽  
Nayef Mazloum ◽  
Sama Tamrakar ◽  
John W Ludlow ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Retinoblastoma Protein ◽  
Catalytic Subunit ◽  
Dna Polymerase Δ

scholarly journals 53BP1 mediated recruitment of RASSF1A at ribosomal DNA breaks facilitates local ATM signal amplification

2021 ◽  
Author(s):  
Stavroula Tsaridou ◽  
Georgia Velimezi ◽  
Frances Willenbrock ◽  
Maria Chatzifrangkeskou ◽  
Andreas Panagopoulos ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Viability ◽  
Copy Number ◽  
Adaptor Proteins ◽  
Fragile Sites ◽  
Dna Lesions ◽  
Dna Breaks ◽  
Damage Response ◽  
Rdna Copy ◽  
Rdna Copy Number

DNA lesions occur across the genome and constitute a threat to cell viability; however, damage at specific genomic loci has a disproportionally greater impact on the overall genome stability. The ribosomal RNA gene repeats (rDNA) are emerging fragile sites due to repetitive nature, clustering and high transcriptional activity. Recent progress in understanding how the rDNA damage response is organized has highlighted the key role of adaptor proteins in the response. Here we identify that the scaffold and tumor suppressor, RASSF1A is recruited at sites of damage and enriched at rDNA breaks. Employing targeted nucleolar DNA damage, we find that RASSF1A recruitment requires ATM activity and depends on 53BP1. At sites of damage RASSF1A facilitates local ATM signal establishment and rDNA break repair. RASSF1A silencing, a common epigenetic event during malignant transformation, results in persistent breaks, rDNA copy number alterations and decreased cell viability. Meta-analysis of a lung adenocarcinoma cohort showed that RASSF1A epigenetic silencing leads in rDNA copy number discrepancies. Overall, we present evidence that RASSF1A acts as a DNA repair factor and offer mechanistic insight in how the nucleolar DNA damage response is organized.

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