TY - JOUR. T1 - Suppression of replication fork progression in low-dose-specific p53-dependent S-phase DNA damage checkpoint. AU - Shimura, T.. AU - Toyoshima, M.. AU - Adiga, S. K.. AU - Kunoh, T.. AU - Nagai, H.. AU - Shimizu, N.. AU - Inoue, M.. AU - Niwa, O.. PY - 2006/9/28. Y1 - 2006/9/28. N2 - The S-phase DNA damage checkpoint is activated by DNA damage to delay DNA synthesis allowing time to resolve the replication block. We previously discovered the p53-dependent S-phase DNA damage checkpoint in mouse zygotes fertilized with irradiated sperm. Here, we report that the same p53 dependency holds in mouse embryonic fibroblasts (MEFs) at low doses of irradiation. DNA synthesis in p53 wild-type (WT) MEFs was suppressed in a biphasic manner in which a sharp decrease below 2.5 Gy was followed by a more moderate decrease up to 10 Gy. In contrast, p53-/- MEFs exhibited radioresistant DNA synthesis below 2.5 Gy whereas the cells retained the moderate suppression above 5 Gy. DNA fiber analysis ...
The Mre11-Rad50-Nbs1 (MRN) complex has many biological functions: processing of double-strand breaks in meiosis, homologous recombination, telomere maintenance, S-phase checkpoint, and genome stability during replication. In the S-phase DNA damage checkpoint, MRN acts both in activation of checkpoint signaling and downstream of the checkpoint kinases to slow DNA replication. Mechanistically, MRN, along with its cofactor Ctp1, is involved in 5 resection to create single-stranded DNA that is required for both signaling and homologous recombination. However, it is unclear whether resection is essential for all of the cellular functions of MRN. To dissect the various roles of MRN, we performed a structure-function analysis of nuclease dead alleles and potential separation-of-function alleles analogous to those found in the human disease ataxia telangiectasia-like disorder, which is caused by mutations in Mre11. We find that several alleles of rad32 (the fission yeast homologue of mre11), along with
Cells were treated with either UVA or TMP/UVA. a Sequential IP demonstrates association of early-replicating Alu sequences with DONSON and late-replicating Satellite 3 sequences with FANCM. LINE-1 elements replicate throughout the S phase and are found in all fractions. Representative blot (n = 3). b DONSON interaction with the H3K4me3 euchromatin mark is more frequent in early S phase cells than in late S phase, while there is little interaction with the H3K9me3 heterochromatin mark in either stage. Sorted early and late S phase cells were examined by PLA. Scored nuclei: PLA between GFP-D: H3K4me3 of early S phase = 67, late S phase = 64, PLA between GFP-D: H3K9me3 of early S phase = 70, late S phase = 85, from three biological replicates. Data are mean ± s.e.m. c FANCM interaction with H3K9me3 heterochromatin mark is biased toward late S phase, while there is low interaction frequency with H3K4me3 in either stage. Scored nuclei: PLA between FANCM: H3K4me3 of early S phase = 64, late S phase = ...
CDC25A plays a role in the unperturbed cell cycle (Ben-Yehoyada et al., 2007); to address the concern that the CDC25A siRNA was slowing down replication, which would affect the result, we pulsed cells with BrdU after 48 h of CDC25A siRNA transfection and chased the cells for 8 h. Flow cytometric analysis revealed that the progression through S phase at these time points was largely unaffected by the lower cellular concentration of CDC25A (Fig. S3 E). Thus, repression of DNA damage after CDC25A depletion is not caused by markedly slowed progression through S phase or G1-phase arrest.. Finally, we asked whether CDC25A accumulation could be an important determinant of the proliferative capability of cells depleted for CHK1 because coknockdown of CDC25A with CHK1 abolished the majority of DNA damage. Importantly, TIG-3-tert cells depleted for CHK1 proliferated very poorly, whereas this phenotype was partly rescued by codepletion of CDC25A. In fact, cells depleted for both CDC25A and CHK1 ...
BioAssay record AID 609847 submitted by ChEMBL: Cell cycle arrest in human HeLaS3 cells assessed as accumulation at S phase at 150 uM after 48 hrs using propidium iodide staining by flow cytometry (Rvb = 19.62%).
To achieve faithful replication of the genome once in each cell cycle, reinitiation of S phase is prevented in G(2) and origins are restricted from refiring within S phase. We have investigated the block to rereplication during G(2) in fission yeast. The DNA synthesis that occurs when G(2)/M cyclin-dependent kinase (CDK) activity is depleted has been assumed to be repeated rounds of S phase without mitosis, but this has not been demonstrated to be the case. We show here that on G(2)/M CDK depletion in G(2), repeated S phases are induced, which are correlated with normal G(1)/S transcription and attainment of doublings in cell size. Mostly normal mitotic S-phase origins are utilized, although at different efficiencies, and replication is essentially equal across the genome. We conclude that CDK inhibits reinitiation of S phase during G(2), and if G(2)/M CDK is depleted, replication results from induction of a largely normal S-phase program with only small differences in origin usage and efficiency ...
In Saccharomyces cerevisiae, a single cyclin-dependent kinase, Cdc28, regulates both G1/S and G2/M phase transitions by associating with stage-specific cyclins. During progression through S phase and G2/M, Cdc28 is activated by the B-type cyclins Clb1-6. Because of functional redundancy, specific roles for individual Clbs have been difficult to assign. To help genetically define such roles, strains carrying a cdc28(ts) allele, combined with single CLB deletions were studied. It is assumed that by limiting the activity of the kinase, these strains would be rendered more sensitive to loss of individual Clbs. By this approach, a novel phenotype associated with CLB5 mutation was observed. Homozygous cdc28-4(ts) clb5 diploids are not viable at room temperature. Cells are defective in spindle positioning, leading to migration of undivided nuclei into the bud. Occasionally, misplaced spindles are observed in cdc28-4 clb5 haploids; additional deletion of CLB6 causes full penetrance. Thus, CLB5 brings ...
numerous post-translational modifications lead to stabil- In contrast to the key role of p53 in maintenance of the isation of the p53 protein and activation of its DNA-induced G1 arrest, no specific roles for p53 or p21 sequence-specific DNA binding [9,30]. Only then can p53 have been implicated in the control of the intra-S-phase efficiently stimulate transcription of cell-cycle inhibitors checkpoint. This is perhaps not so surprising as the such as p21 (Figure 2). Furthermore, the p21 protein has to S-phase checkpoint, manifested by a decreased rate of accumulate to levels sufficiently high to inhibit the CDK- DNA synthesis after generation of DSBs, is by definition a containing complexes, before cell-cycle progression transient phenomenon [5]. The absence of the mainte- becomes efficiently blocked. Although p53 has recently nance component during S phase, contrary to the G1 and been described binding to 5′ untranslated region of CDK4 G2 checkpoints, might be beneficial for the cells by ...
ABSTRACTAims:Breast cancer is the major diagnosed cancer and the leading reason of cancer related death among women, and the tumor size is one of the risk factors. Therefore, it is significant to reveal the principle of breaking the subtle homeostasis of cell cycle and sustaining chronic proliferati
Faithful duplication and segregation of undamaged DNA is critical to the survival of all organisms and prevention of oncogenesis in multicellular organisms. To ensure inheritance of intact DNA, cells rely on checkpoints. Checkpoints alter cellular processes in the presence of DNA damage preventing cell cycle transitions until replication is completed or DNA damage is repaired. Several checkpoints are specific to S-phase. The S-M replication checkpoint prevents mitosis in the presence of unreplicated DNA. Rather than outright halting replication, the S-phase DNA damage checkpoint slows replication in response to DNA damage. This checkpoint utilizes two general mechanisms to slow replication. First, this checkpoint prevents origin firing thus limiting the number of replication forks traversing the genome in the presence of damaged DNA. Second, this checkpoint slows the progression of the replication forks. Inhibition of origin firing in response to DNA damage is well established, however when this thesis
To maintain genome stability, DNA replication occurs only once in each cell cycle. This is achieved by the cell cycle-dependent licensing control that permits assembly of prereplication complexes (pre-RCs) at replication origins only once per cell cycle (Mendez and Stillman, 2003; Diffley, 2004; Nishitani and Lygerou, 2004; Blow and Dutta, 2005; Arias and Walter, 2007). On exit from metaphase, the minichromosome maintenance (MCM) 2-7 complex is recruited to replication origins to establish pre-RCs. Once replication is activated by the Cdks and Cdc7/Dbf4 kinase, pre-RCs are disassembled and the reassociation of MCM proteins with origins is not permitted until the completion of mitosis.. Regulation of Cdt1 activity during the cell cycle is critical for the prevention of reassembly of pre-RCs within a single cell cycle (Blow and Dutta, 2005; Arias and Walter, 2007). When cells enter S phase, Cdt1 is ubiquitinated and degraded (Nishitani et al., 2001; Li et al., 2003; Zhong et al., 2003; Arias and ...
In the absence of Rif1, this mid‐S‐phase architecture is not formed, allowing Cdc7 kinase to gain access in early‐S‐phase to the origins that would normally not be activated until mid‐S‐phase. This would explain the increased Cdc7‐dependent phosphorylation of the target proteins and hyper‐loading of Cdc45 and PCNA onto chromatin in Rif1‐depleted cells at early‐S‐phase (Figure 1). As a result of loss of mid‐S replication domains, replication timing domain structures may undergo genome‐wide alteration. It should be noted that replication timing is generally more centred to mid‐S in the absence of Rif1, although mid‐S replication foci pattern is lost and all the replication foci appear to adopt the early‐S‐like pattern (Supplementary Figure S9). This effect of Rif1 on replication timing is similar to what we observed in fission yeast rif1Δ mutant, where some early‐firing origins are delayed and late‐firing/dormant origins are fired earlier (Hayano et al, ...
Clinical experience has shown that mammary carcinomas can be classified according to their type of progression into slow-growing and fast-growing ones, where the terms
A stochastic model for interpreting BrdUrd DNA FCM-derived data is proposed. The model is based on branching processes and describes the progression of the DNA distribution of BrdUrd-labelled cells through the cell cycle. With the main focus on estimating the S phase duration and its variation, the DNA replication rate is modelled by a piecewise linear function, while assuming a gamma distribution for the S phase duration. Estimation of model parameters was carried out using maximum likelihood for data from two different cell lines. The results provided quite a good fit to the data, suggesting that stochastic models may be a valuable tool for analysing this kind of data.
Cyclin-dependent Kinase Inhibitor (CKI); Inhibitor Of Cdc28-Clb Kinase Complexes That Controls G1/S Phase Transition, Preventing Premature S Phase And Ensuring Genomic Integrity; Phosphorylated By Clb5/6-Cdk1 And Cln1/2-Cdk1 Kinase Which Regulate Timing Of Sic1p Degradation; Phosphorylation Targets Sic1p For SCF(CDC4)-dependent Turnover; Functional Homolog Of Mammalian Kip1
The precise replication of the genome and the continuous surveillance of its integrity are essential for survival and the avoidance of various diseases. Cells respond to DNA damage by activating a complex network of the so-called checkpoint pathways to delay their cell-cycle progression and repair t …
In this study we show that CPS and nordihydrocapsiate (CPT) inhibit early and late events in T cell activation, including CD69, CD25 and ICAM-1 cell surface expression, progression to the S phase of the cell cycle and proliferation in response to TCR and CD28 co-engagement ...
Cells divide with remarkable fidelity, allowing complex organisms to develop and possess longevity. Checkpoint controls contribute by ensuring that genome duplication and segregation occur without error so that genomic instability, associated with developmental abnormalities and a hallmark of most human cancers, is avoided. S-phase checkpoints prevent cell division while DNA is replicating. Budding yeast Mec1p and Rad53p, homologues of human checkpoint kinases ATM/ATR and Chk2, are needed for this control system. How Mec1p and Rad53p prevent mitosis in S phase is not known. Here we provide evidence that budding yeasts avoid mitosis during S phase by regulating the anaphase-promoting complex (APC) specificity factor Cdc20p: Mec1p and Rad53p repress the accumulation of Cdc20p in S phase. Because precocious Cdc20p accumulation causes anaphase onset and aneuploidy, Cdc20p concentrations must be precisely regulated during each and every cell cycle. Catastrophic mitosis induced by Cdc20p in S phase ...
TY - JOUR. T1 - SU9516, a cyclin-dependent kinase 2 inhibitor, promotes accumulation of high molecular weight E2F complexes in human colon carcinoma cells. AU - Yu, Bo. AU - Lane, Maureen E.. AU - Wadler, Scott. PY - 2002/10/1. Y1 - 2002/10/1. N2 - The E2F family plays a critical role in the expression of genes required for entry into and progression through S phase. E2F-mediated transcription is repressed by the tumor suppressor retinoblastoma protein (pRb), which results in sequestration of E2F in a multiprotein complex that includes pRb. Derepression of E2F results from a series of complex phosphorylation events mediated by cyclin D/cdk4 and cyclin E/cdk2. We have employed a novel 3-substituted indolinone compound, 3-[1-(3H-imidazol-4-yl)-meth-(Z)-ylidene]-5-methoxy-1,3-dihydro-indol-2-one (SU9516), which selectively inhibits cdk2 activity (Lane et al., Cancer Res 2001;61:6170-7) to investigate these events. Electrophoretic mobility gel shift assays were performed on SU9516-treated and ...
Muktadir S. Hossain completed his Ph.D. at the University of Tokyo, Japan in 2004 where he showed that quiescent (G0) phase cells of multicellular eukaryotes like mammals and insects require DNA topoisomeras II enzyme for the re-entry into the cell cycle, whereas the unicellular eukaryotes like yeast do not. The title of his Ph.D. dissertation is "Requirement for DNA topoisomerase II during the G0-to-S phase transition in mammalian and insect cells". In the University of Tokyo as a Ph.D. student, he participated in the isolation of temperature-sensitive mutants of the pathogenic bacterium, Staphylococcus aureus. In the University of Tokyo as a Ph.D. student, he also showed that the DNA double-strand break-inducing drugs that are used to treat cancner can induce myogenic differentiation in cultured cells of the fruit fly, Drosophila melanogaster. In the University of Tokyo as a Research Assistant, he established the larvae of the silk moth, Bombyx mori as animal model to study purified toxins ...
Synchronized VSMCs were obtained by the method of double-thymidine block,colchicine treatment and serum starvation . Synchronized growth was monitored by flow cytometry. All the synchronized VSMCs distribution ration were 89.22% (±3.54%) at G0 phase, (66.74±7.16%) at G1/S phase, (63.24±4.06)% at S phase and (51.64±11.18)% at G2/M phase. The expression of ORC1 mRNA and CyclinA in a quiescent stage of VSMC was not significantly found, After synchronized, peaked(50.4%) at G2/M of CyclinA, and decreased(1.03%) at G2/M of ORC1, CyclinA in preventing the ORC1 from bind during G2/Mphase. The expression of ORC1 protein and CyclinA had a same change as ORC1 mRNA and CyclinA in different cell cycles of VSMC by flow cytometry (P,0.001). ...
Chromosome replication is a key event in the eukaryotic cell division cycle. During S phase the entire genome must be faithfully duplicated with the minimum of errors. The many thousands of replication forks involved in this process must be co-ordinated to ensure that despite the very large quantities of DNA involved, no section of DNA is left unreplicated and no section of DNA is replicated more than once. Cells achieve this by having a distinct stage that occurs prior to S phase when replication origins are "licensed" for replication. At the onset of S phase, replication forks are initiated only at these licensed replication origins. As initiation occurs at each origin, the licence is removed, thereby ensuring that it fires only once in each cell cycle. Mistakes made in this process may cause irreversible genetic modifications that could ultimately lead to the cells becoming cancerous. Many early stage cancer cells have lost the ability to correctly down-regulate the licensing system, ...
p21CDKN1A does not interfere with loading of PCNA at DNA replication sites, but inhibits subsequent binding of DNA polymerase delta at the G1/S phase transition.
BioAssay record AID 461873 submitted by ChEMBL: Cell cycle arrest in human HeLa cells assessed as increase in S phase accumulation at 10 uM after 24 hrs by FACS analysis.
E, CAL120 cells were either untreated or pretreated with gemcitabine for 24 hours followed by treatment with AZD7762 and /or MK-1775 for an additional 2 hours (top) or 8 hours (bottom), before lysis. Western blot analysis of Cyclin B1, CDK1 (phospho-Y15 and total) expression, and β-tubulin as loading control. F, induction of the intra-S-phase checkpoint was not affected by WEE1 inhibition. CAL120 cells were pulse-labeled with 10 μmol/L BrdU for 30 minutes, washed (W), and then treated with 1 μmol/L camptothecin (CPT) for 30 minutes. After CPT removal (0 hours), BrdU-labeled S-phase cells (BrdU+ , indicated by boxed area) were monitored at the indicated time points in the absence (iii) or presence of MK-1775 (iv) or AZD7762 as a positive control (v). Control cells (ctr) were not exposed to CPT and cultured in the absence (i) or presence of MK-1775 (ii). Arrowheads indicate delayed S-phase progression.. ...
Fidelity of histone gene regulation, and ultimately of histone protein biosynthesis, is obligatory for packaging of newly replicated DNA into chromatin. Control of histone gene expression within the 3‐dimensional context of nuclear organization is reflected by two well documented observations....
The end of the S phase of the cell cycle leads to G2 phase, which in turns leads to the M phase or mitosis. During G2 phase, there must be an increasing amount of molecules needed for M phase. G2 phase has been traditionally regarded as a transitional phase between S and M phases. However, during G2 phase, it is checked if any error occurred during DNA replication and if the DNA has been completely replicated. If something went wrong during S phase, M phase does not start until the errors are repaired. It is of great importance the detection of errors before M phase starts, otherwise they will be inherited by the daughter cells. During G2 phase, cell increases the size, and centrosomes of animal cells, duplicated during S phase too, are positioned at opposite locations of the cytoplasm for starting the polymerization of the mitotic spindle during M phase. ...
TY - JOUR. T1 - Rapid cell cycle analysis. II. Phase durations and dispersions from computer analysis of RC curves.. AU - Gray, J. W.. AU - Bogart, E.. AU - Gavel, D. T.. AU - George, Y. S.. AU - Moore, D. H.. PY - 1983/9. Y1 - 1983/9. N2 - In this paper, we present a procedure for the rapid, quantitative estimation of the G1, S, and G2 + M phase durations and dispersions and the growth fraction for asynchronously growing cell populations. In this procedure, the cell population is pulse-labelled with a radioactive DNA precursor at the beginning of the analysis and then sampled periodically. The samples are dispersed, stained with a DNA specific dye, and processed through a cell sorter where cells from mid-S phase and G1 phase are sorted. The radioactivity per cell (RC) is determined for each sorted sample. In addition, the variation in the rate of incorporation of the radioactive DNA precursor across S phase is determined and the fractions of cells in the G1, S, and G2 + M phase are estimated ...
Replication times for all important chromosome bands, of both types R and Q (277 structures) are analysed. - The R-bands form a group of structures whose DNA replicates during the early S-phase, while
Flow-cytometric analysis was used to examine the cell cycle characteristics of BMKs from each of the three genotypes ( Fig. 4A), and the data shown are representative of three independently derived cultures from each genotype. LSL-K-rasG12D BMKs infected with Ad-Cre displayed a higher percentage of cells in G1 and S phases (40.8% and 15.2%, respectively) than control cells (33.4% and 11.5%, respectively). We believe that this is indicative of an increased rate of exit from G2-M and increased cellular proliferation, as supported by data obtained from daily cell counts in LSL-K-rasG12D BMKs (see Fig. 4C and below). Importantly, Ad-Cre-infected Rac1flox/flox BMKs displayed similar growth kinetics to LSL-K-rasG12D BMKs (39.6% of cells in the G1 phase and 13.5% in the S phase compared with controls at 34.9% in the G1 phase and 11.6% in the S phase). Thus, in BMK cells, loss of Rac1 function alone is not lethal and is compatible with proliferation. In contrast, following Ad-Cre infection, ...
Components and dynamics of DNA replication complexes in S. cerevisiae: Redistribution of MCM proteins and Cdc45p during S phase ...
Dates: 7 - 10 May 2018 Registration: 26 Mar 18 Abstract: 12 Feb 18 Event webpage: www.embo-embl-symposia.org/symposia/2018/EES18-02/index.html Aim:There has been tremendous progress in the past few years regarding our understanding of DNA replication in eukaryotes, both yeast and mammals. Many important questions in the field are poised to be answered within the next decade. These include understanding DNA replication at the biochemical and three-dimensional protein structure levels. In addition, studies using high throughput technologies at the cellular and organismal levels are poised to answer how accurate replication of the genome is ensured by controlling origin firing in space and time.Several human diseases, including cancer, have already been linked to DNA replication stress, a term that refers to perturbations in DNA replication. Thus, a better understanding of how cells respond to DNA replication stress will help us understand disease development and responses to therapy. By bringing ...
Malignant proliferation is the fundamental trait of tumor cells. The initiation of DNA replication represents a key process for cell proliferation, and has a marked impact on tumorigenesis and progression (19,21). The factors that promote DNA replication are organized in multiprotein complexes that coordinately help to recognize regions of origin, unwind DNA and promote replisome formation (21). The data in this study showed that SIX1 could modulate the expression of several genes related to DNA replication, thus accelerating G1 to S phase progression, promoting the proliferation of cervical cancer cells in vitro, and promoting the growth of cervical cancer in vivo.. The expression of SIX1 was closely correlated with the progression of cervical cancer as shown by our data. High levels of SIX1 expression were observed in almost all regions that developed intraepithelial neoplasia, suggesting that SIX1 might play an important role in tumorigenesis and progression of cervical cancer. Our data ...
As its role in tumor progression emerges, the PI3K/PKB (Akt) pathway presents an appealing cancer therapeutic target. Recent studies have investigated the mechanisms underlying the tumor-promoting effects of this pathway. PKB triggers a network that positively regulates G1/S cell cycle progression t …
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Wet-lab validated real-time PCR primer assays for your biological pathway of interest. Select your gene target of interest using an interactive pathway map, and select your plate.
Tweet. End Sociable. Related posts:. 1The Institute of Science in Society raises serious concerns about the Cauliflower Mosaic Viral Promoter found in commercial GMOS. A recently released study by Podevain and du Jardin in 2012…. A major consequence of mutant p53 degradation in tumor cells after glucose deprivation is the loss of a critical check on the autophagic process that results in increased autophagy and leads to cell death (Fig. 1). Importantly, wild type p53 has been previously demonstrated to protect cells from glucose deprivation through induction of a reversible G1/S phase cell cycle arrest, suggesting that normal tissues will respond to glucose shortage differently than tumors harboring mutant p53.1. fig ft0fig mode=article f1. Taken together, these findings strongly indicate that some tumor-promoting forms of mutant p53 can be targeted for autophagic degradation through glucose restriction. These exciting results could be tested in the clinic by randomizing patients with tumors ...
Above the next 36 h, we quantified by movement cytometry the fee of EdU nucleotide analogue incor poration through the cells and their overall DNA content, which allowed us to assign cells to G0G1, S, and G2M phases of your cell cycle. Inhibitors,Modulators,Libraries When compared to cells transfected using a manage non focusing on microRNA, cells transfected with miR 29 contained fewer cells in G0G1 and even more cells in S phase at twenty and 24 h publish transfec tion. At 28 and 32 h right after trans fection, cells transfected with miR 29 contained fewer cells in S phase and much more cells in G2M phase than people transfected with all the control. miR 29 overexpression as a result hastens re entry to the cell cycle from a quiescent state. To additional check out the results of miR 29 expression within the cell cycle, we transfected miR 29 or maybe a negative control microRNA into asynchronously cycling fibroblasts.. Forty eight hours post transfection, miR 29 transfection led to extra cells ...
Precise coordination of the S and M phases of the eukaryotic cell cycle is critical not only for normal cell division, but also for effective growth arrest under conditions of stress. When damaged, a cell must communicate signals to both the mitotic
MITOSIS: The division of chromosomes in the nucleus. S phase: duplication of DNA. (to form two complete copies of each chromosome).
Wellbutrin (bupropion) is an energizer used to treat significant depressive issue and occasional full of feeling issue. This medication works by obstructing the reuptake of norepinephrine and dopamine in the mind, in this way adjusting particular normal s
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If you have a question about this talk, please contact Kathryn Gooch.. Abstract not available. This talk is part of the Seminars at the Department of Biochemistry series.. ...
Cdc7-Dbf4 is an essential protein kinase complex required for every single origin firing. As a target of the intra-S checkpoint, Cdc7 kinase activity has also been implicated in the response to replication fork stress, with a role in translesion DNA synthesis (TLS). We have examined the role of Cdc7 in the regulation of replication forks, particularly in response to MMS, which normally stalls replication forks and inhibits late origin firing. We find that replication forks proceed as fast as with no damage along an MMS-damaged template both in cdc7as3 and cdc7-1/mcm5-bob1 cells. However the DNA synthesis in cdc7-1/mcm5-bob1 in MMS is defective, indicated by the slower recovery after MMS by PFGE, suggesting the replication is incomplete. These deregulated forks did not rely on TLS pathway but are dependent on both helicase and E3 ligase function of Rad5 for continued fork progression along MMS-damaged DNA, demonstrating a role for Rad5 at the replication fork. Phosphorylation of MCM2 by DDK was ...
The cellular response to DNA damage is critical for maintenance of genomic integrity and inhibition of tumorigenesis. Mutations or aberrant expression of the E3 ubiquitin ligase EDD have been observed in a number of carcinomas and we recently reported that EDD modulates activity of the DNA damage checkpoint kinase, CHK2. Here, we demonstrate that EDD is necessary for G(1)/S and intra S phase DNA damage checkpoint activation and for the maintenance of G(2)/M arrest after double strand DNA breaks. Defective checkpoint activation in EDD-depleted cells led to radio-resistant DNA synthesis, premature entry into mitosis, accumulation of polyploid cells, and cell death via mitotic catastrophe. In addition to decreased CHK2 activation in EDD-depleted cells, the expression of several key cell cycle mediators including Cdc25A/C and E2F1 was altered, suggesting that these checkpoint defects may be both CHK2-dependent and -independent. These data support a role for EDD in the maintenance of genomic stability,
Genomic instability plays a key role in driving cancer development. It is already found in precancerous lesions and allows the acquisition of additional cancerous features. A major source of genomic instability in early stages of tumorigenesis is DNA replication stress. Normally, origin licensing and activation, as well as replication fork progression, are tightly regulated to allow faithful duplication of the genome. Aberrant origin usage and/or perturbed replication fork progression leads to DNA damage and genomic instability. Oncogene activation is an endogenous source of replication stress, disrupting replication regulation and inducing DNA damage. Oncogene-induced replication stress and its role in cancer development have been studied comprehensively, however its molecular basis is still unclear. Here, we review the current understanding of replication regulation, its potential disruption and how oncogenes perturb the replication and induce DNA damage leading to genomic instability in cancer.
The aim of the present work was to investigate the occurrence of the cell cycle during germination as related to thermodormancy in barley (Hordeum vulgare L., cv. Pewter) grains in relation with abscisic acid (ABA) by: (i) flow cytometry to determine the progression of the cell cycle; and (ii) reverse transcription-PCR to characterize the expression of some important genes involved in cell-cycle regulation. In dry embryos, cells are mostly (82%) arrested in G1 phase of the cell cycle, the remaining cells being in the G2 (17%) or S phase (0.9%). Germination at 20 °C was associated with an increase in the nuclei population in G2 and S (up to 32.5-44.5 and 9.2-11.3%, respectively, after 18-24h). At 30 °C, partial reactivation of the cell cycle occurred in embryos of dormant grains that did not germinate. Incubation with 50mM hydroxyurea suggests that thermodormancy resulted in a blocking of the nuclei in the S phase. In dry dormant grains, transcripts of CDKA1, CYCA3, KRP4, and WEE1 were present, while
TY - JOUR. T1 - A mammalian bromodomain protein, Brd4, interacts with replication factor C and inhibits progression to S phase. AU - Maruyama, Tetsuo. AU - Farina, Andrea. AU - Dey, Anup. AU - Cheong, JaeHun. AU - Bermudez, Vladimir P.. AU - Tamura, Tomohiko. AU - Sciortino, Selvaggia. AU - Shuman, Jon. AU - Hurwitz, Jerard. AU - Ozato, Keiko. PY - 2002/9. Y1 - 2002/9. N2 - Brd4 belongs to the BET family of nuclear proteins that carry two bromodomains implicated in the interaction with chromatin. Expression of Brd4 correlates with cell growth and is induced during early G1 upon mitogenic stimuli. In the present study, we investigated the role of Brd4 in cell growth regulation. We found that ectopic expression of Brd4 in NIH 3T3 and HeLa cells inhibits cell cycle progression from G1 to S. Coimmunoprecipitation experiments showed that endogenous and transfected Brd4 interacts with replication factor C (RFC), the conserved five-subunit complex essential for DNA replication. In vitro analysis showed ...
Authors: Abad, Mar , Ciudad, Juana , Rincon, Manuel R. , Silva, Isabel , Paz‐Bouza, José I. , Lopez, Antonio , Alonso, Alberto G. , Bullon, Agustin , Orfao, Alberto Article Type: Research Article Abstract: In the present study the prognostic value of both DNA ploidy and the proliferative activity of tomour cells were studied in a series of 76 consecutive patients suffering from gastric tumours. DNA ploidy and the proliferative index (as measured by the percentage of S‐phase cells) were determined by flow cytometry using fresh tumour specimens. The presence of DNA aneuploid clones by flow cytometry was detected in 62% of the cases (mean DNA index of 1.63\pm 0.46 ; range 1.08-2.92), the mean proportion of S‐phase cells being of 18.4\pm 11.5\% . In comparison with diploid cases, aneuploid tumours …showed a higher proliferative activity (cases with more than 15% S‐phase cells: 18.4% versus 6.1%, p=0.0001 ) as well as a higher incidence of node involvement (95% versus 68%, p=0.001 ). By ...