scholarly journals Human DNA Polymerase η Is Required for Common Fragile Site Stability during Unperturbed DNA Replication

2009 ◽  
Vol 29 (12) ◽  
pp. 3344-3354 ◽  
Author(s):  
Laurie Rey ◽  
Julia M. Sidorova ◽  
Nadine Puget ◽  
François Boudsocq ◽  
Denis S. F. Biard ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Polymerase ◽  
Genome Stability ◽  
Fragile Site ◽  
S Phase ◽  
Human Cells ◽  
Common Fragile Site ◽  
Exogenous Dna ◽  
Human Dna

ABSTRACT Human DNA polymerase η (Pol η) modulates susceptibility to skin cancer by promoting translesion DNA synthesis (TLS) past sunlight-induced cyclobutane pyrimidine dimers. Despite its well-established role in TLS synthesis, the role of Pol η in maintaining genome stability in the absence of external DNA damage has not been well explored. We show here that short hairpin RNA-mediated depletion of Pol η from undamaged human cells affects cell cycle progression and the rate of cell proliferation and results in increased spontaneous chromosome breaks and common fragile site expression with the activation of ATM-mediated DNA damage checkpoint signaling. These phenotypes were also observed in association with modified replication factory dynamics during S phase. In contrast to that seen in Pol η-depleted cells, none of these cellular or karyotypic defects were observed in cells depleted for Pol ι, the closest relative of Pol η. Our results identify a new role for Pol η in maintaining genomic stability during unperturbed S phase and challenge the idea that the sole functional role of Pol η in human cells is in TLS DNA damage tolerance and/or repair pathways following exogenous DNA damage.

scholarly journals Role of inhibitory CDC2 phosphorylation in radiation-induced G2 arrest in human cells.

1996 ◽  
Vol 134 (4) ◽  
pp. 963-970 ◽  
Author(s):  
P Jin ◽  
Y Gu ◽  
D O Morgan
Keyword(s):  
Dna Damage ◽  
Chromatin Condensation ◽  
S Phase ◽  
Human Cells ◽  
G2 Arrest ◽  
Hela Cell Lines ◽  
Radiation Induced ◽  
G2 Delay ◽  
In Cells

The activity of the mitosis-promoting kinase CDC2-cyclin B is normally suppressed in S phase and G2 by inhibitory phosphorylation at Thr14 and Tyr15. This work explores the possibility that these phosphorylations are responsible for the G2 arrest that occurs in human cells after DNA damage. HeLa cell lines were established in which CDC2AF, a mutant that cannot be phosphorylated at Thr14 and Tyr15, was expressed from a tetracycline-repressible promoter. Expression of CDC2AF did not induce mitotic events in cells arrested at the beginning of S phase with DNA synthesis inhibitors, but induced low levels of premature chromatin condensation in cells progressing through S phase and G2. Expression of CDC2AF greatly reduced the G2 delay that resulted when cells were X-irradiated in S phase. However, a significant G2 delay was still observed and was accompanied by high CDC2-associated kinase activity. Expression of wild-type CDC2, or the related kinase CDK2AF, had no effect on the radiation-induced delay. Thus, inhibitory phosphorylation of CDC2, as well as additional undefined mechanisms, delay mitosis after DNA damage.

scholarly journals The role of Sp1 in the detection and elimination of cells with persistent DNA strand breaks

NAR Cancer ◽  
2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Polina S Loshchenova ◽  
Svetlana V Sergeeva ◽  
Sally C Fletcher ◽  
Grigory L Dianov
Keyword(s):  
Dna Damage ◽  
Cancer Therapy ◽  
Genome Stability ◽  
Dna Strand Breaks ◽  
Dna Lesions ◽  
Exogenous Dna ◽  
Strand Breaks ◽  
Specificity Factor ◽  
Dna Strand

Abstract Maintenance of genome stability suppresses cancer and other human diseases and is critical for organism survival. Inevitably, during a life span, multiple DNA lesions can arise due to the inherent instability of DNA molecules or due to endogenous or exogenous DNA damaging factors. To avoid malignant transformation of cells with damaged DNA, multiple mechanisms have evolved to repair DNA or to detect and eradicate cells accumulating unrepaired DNA damage. In this review, we discuss recent findings on the role of Sp1 (specificity factor 1) in the detection and elimination of cells accumulating persistent DNA strand breaks. We also discuss how this mechanism may contribute to the maintenance of physiological populations of healthy cells in an organism, thus preventing cancer formation, and the possible application of these findings in cancer therapy.

scholarly journals Human Mcm10 Regulates the Catalytic Subunit of DNA Polymerase-α and Prevents DNA Damage during Replication

2007 ◽  
Vol 18 (10) ◽  
pp. 4085-4095 ◽  
Author(s):  
Sharbani Chattopadhyay ◽  
Anja-Katrin Bielinsky
Keyword(s):  
Dna Damage ◽  
Dna Polymerase ◽  
S Phase ◽  
Human Cells ◽  
Replication Initiation ◽  
Catalytic Subunit ◽  
Drosophila Embryo ◽  
Minichromosome Maintenance ◽  
Α Subunit ◽  
Phase Entry

In Saccharomyces cerevisiae, minichromosome maintenance protein (Mcm) 10 interacts with DNA polymerase (pol)-α and functions as a nuclear chaperone for the catalytic subunit, which is rapidly degraded in the absence of Mcm10. We report here that the interaction between Mcm10 and pol-α is conserved in human cells. We used a small interfering RNA-based approach to deplete Mcm10 in HeLa cells, and we observed that the catalytic subunit of pol-α, p180, was degraded with similar kinetics as Mcm10, whereas the regulatory pol-α subunit, p68, remained unaffected. Simultaneous loss of Mcm10 and p180 inhibited S phase entry and led to an accumulation of already replicating cells in late S/G2 as a result of DNA damage, which triggered apoptosis in a subpopulation of cells. These phenotypes differed considerably from analogous studies in Drosophila embryo cells that did not exhibit a similar arrest. To further dissect the roles of Mcm10 and p180 in human cells, we depleted p180 alone and observed a significant delay in S phase entry and fork progression but little effect on cell viability. These results argue that cells can tolerate low levels of p180 as long as Mcm10 is present to “recycle” it. Thus, human Mcm10 regulates both replication initiation and elongation and maintains genome integrity.

scholarly journals Rev1 promotes replication through UV lesions in conjunction with DNA polymerases η, ι, and κ but not DNA polymerase ζ

2015 ◽  
Vol 29 (24) ◽  
pp. 2588-2602 ◽  
Author(s):  
Jung-Hoon Yoon ◽  
Jeseong Park ◽  
Juan Conde ◽  
Maki Wakamiya ◽  
Louise Prakash ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Crucial Role ◽  
Genome Stability ◽  
Dna Polymerases ◽  
Translesion Synthesis ◽  
Dna Lesions ◽  
Human Cells ◽  
Uv Lesions ◽  
Human And Mouse

Translesion synthesis (TLS) DNA polymerases (Pols) promote replication through DNA lesions; however, little is known about the protein factors that affect their function in human cells. In yeast, Rev1 plays a noncatalytic role as an indispensable component of Polζ, and Polζ together with Rev1 mediates a highly mutagenic mode of TLS. However, how Rev1 functions in TLS and mutagenesis in human cells has remained unclear. Here we determined the role of Rev1 in TLS opposite UV lesions in human and mouse fibroblasts and showed that Rev1 is indispensable for TLS mediated by Polη, Polι, and Polκ but is not required for TLS by Polζ. In contrast to its role in mutagenic TLS in yeast, Rev1 promotes predominantly error-free TLS opposite UV lesions in humans. The identification of Rev1 as an indispensable scaffolding component for Polη, Polι, and Polκ, which function in TLS in highly specialized ways opposite a diverse array of DNA lesions and act in a predominantly error-free manner, implicates a crucial role for Rev1 in the maintenance of genome stability in humans.

scholarly journals Role of DNA polymerase θ in tolerance of endogenous and exogenous DNA damage in mouse B cells

2005 ◽  
Vol 11 (2) ◽  
pp. 111-121 ◽  
Author(s):  
Akiko Ukai ◽  
Takako Maruyama ◽  
Shigenobu Mochizuki ◽  
Rika Ouchida ◽  
Keiji Masuda ◽  
...  
Keyword(s):  
Dna Damage ◽  
B Cells ◽  
Dna Polymerase ◽  
Exogenous Dna

scholarly journals DNA structure and the Werner protein modulate human DNA polymerase delta-dependent replication dynamics within the common fragile site FRA16D

2009 ◽  
Vol 38 (4) ◽  
pp. 1149-1162 ◽  
Author(s):  
Sandeep N. Shah ◽  
Patricia L. Opresko ◽  
Xiao Meng ◽  
Marietta Y. W. T. Lee ◽  
Kristin A. Eckert
Keyword(s):  
Dna Polymerase ◽  
Fragile Site ◽  
Dna Structure ◽  
Common Fragile Site ◽  
Dna Polymerase Delta ◽  
Human Dna ◽  
The Common ◽  
Werner Protein

scholarly journals Regulation of DNA Replication Licensing and Re-Replication by Cdt1

2021 ◽  
Vol 22 (10) ◽  
pp. 5195
Author(s):  
Hui Zhang
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Genome Stability ◽  
E3 Ligase ◽  
S Phase ◽  
Replication Initiation ◽  
Nuclear Antigen ◽  
Repair Synthesis ◽  
Ubiquitin E3 Ligase

In eukaryotic cells, DNA replication licensing is precisely regulated to ensure that the initiation of genomic DNA replication in S phase occurs once and only once for each mitotic cell division. A key regulatory mechanism by which DNA re-replication is suppressed is the S phase-dependent proteolysis of Cdt1, an essential replication protein for licensing DNA replication origins by loading the Mcm2-7 replication helicase for DNA duplication in S phase. Cdt1 degradation is mediated by CRL4Cdt2 ubiquitin E3 ligase, which further requires Cdt1 binding to proliferating cell nuclear antigen (PCNA) through a PIP box domain in Cdt1 during DNA synthesis. Recent studies found that Cdt2, the specific subunit of CRL4Cdt2 ubiquitin E3 ligase that targets Cdt1 for degradation, also contains an evolutionarily conserved PIP box-like domain that mediates the interaction with PCNA. These findings suggest that the initiation and elongation of DNA replication or DNA damage-induced repair synthesis provide a novel mechanism by which Cdt1 and CRL4Cdt2 are both recruited onto the trimeric PCNA clamp encircling the replicating DNA strands to promote the interaction between Cdt1 and CRL4Cdt2. The proximity of PCNA-bound Cdt1 to CRL4Cdt2 facilitates the destruction of Cdt1 in response to DNA damage or after DNA replication initiation to prevent DNA re-replication in the cell cycle. CRL4Cdt2 ubiquitin E3 ligase may also regulate the degradation of other PIP box-containing proteins, such as CDK inhibitor p21 and histone methylase Set8, to regulate DNA replication licensing, cell cycle progression, DNA repair, and genome stability by directly interacting with PCNA during DNA replication and repair synthesis.

scholarly journals Silencing of human DNA polymerase λ causes replication stress and is synthetically lethal with an impaired S phase checkpoint

2012 ◽  
Vol 41 (1) ◽  
pp. 229-241 ◽  
Author(s):  
Elisa Zucca ◽  
Federica Bertoletti ◽  
Ursula Wimmer ◽  
Elena Ferrari ◽  
Giuliano Mazzini ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Replication Stress ◽  
S Phase ◽  
Human Dna ◽  
Dna Polymerase Λ ◽  
Synthetically Lethal ◽  
S Phase Checkpoint

AMPK blocks chromatin activation and consequent R-loop formation to protect genome stability following acute starvation

2021 ◽  
Author(s):  
Bing Sun ◽  
McLean Sherrin ◽  
Richard Roy
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Germ Line ◽  
Critical Role ◽  
Significant Proportion ◽  
Loop Formation ◽  
C Elegans ◽  
Chromatin Activation ◽  
Acute Starvation

Abstract During periods of starvation organisms must modify both gene expression and metabolic pathways to adjust to the energy stress. We previously reported that C. elegans that lack AMPK have transgenerational reproductive defects that result from abnormally elevated H3K4me3 levels in the germ line following recovery from acute starvation1. Here we show that H3K4me3 is dramatically increased at promoters, driving aberrant transcription elongation that results in the accumulation of R-loops in the starved AMPK mutants. DRIP-seq analysis demonstrated that a significant proportion of the genome was affected by R-loop formation with a dramatic expansion in the number of R-loops at numerous loci, most pronounced at the promoter-TSS regions of genes in the starved AMPK mutants. The R-loops are transmissible into subsequent generations, likely contributing to the transgenerational reproductive defects typical of these mutants following starvation. Strikingly, AMPK null germ lines show considerably more RAD-51 foci at sites of R-loop formation, potentially sequestering it from its critical role at meiotic breaks and/or at sites of induced DNA damage. Our study reveals a previously unforeseen role of AMPK in maintaining genome stability following starvation, where in its absence R-loops accumulate, resulting in reproductive compromise and DNA damage hypersensitivity.

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