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dna%2Bdamage


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  • Growth arrest DNA damage-inducible gene 45 gamma expression as a prognostic and predictive biomarker in hepatocellular carcinoma. 26172295

    Growth arrest DNA damage-inducible gene 45 (GADD45) family proteins play a crucial role in regulating cellular stress responses and apoptosis. The present study explored the prognostic and predictive role of GADD45γ in hepatocellular carcinoma (HCC) treatment. GADD45γ expression in HCC cells was examined using quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. The control of GADD45γ transcription was examined using a luciferase reporter assay and chromatin immunoprecipitation. The in vivo induction of GADD45γ was performed using adenoviral transfer. The expression of GADD45γ in HCC tumor tissues from patients who had undergone curative resection was measured using qRT-PCR. Sorafenib induced expression of GADD45γ mRNA and protein, independent of its RAF kinase inhibitor activity. GADD45γ induction was more prominent in sorafenib-sensitive HCC cells (Huh-7 and HepG2, IC50 6-7 μM) than in sorafenib-resistant HCC cells (Hep3B, Huh-7R, and HepG2R, IC50 12-15 μM). Overexpression of GADD45γ reversed sorafenib resistance in vitro and in vivo, whereas GADD45γ expression knockdown by using siRNA partially abrogated the proapoptotic effects of sorafenib on sorafenib-sensitive cells. Overexpression of survivin in HCC cells abolished the antitumor enhancement between GADD45γ overexpression and sorafenib treatment, suggesting that survivin is a crucial mediator of antitumor effects of GADD45γ. GADD45γ expression decreased in tumors from patients with HCC who had undergone curative surgery, and low GADD45γ expression was an independent prognostic factor for poor survival, in addition to old age and vascular invasion. The preceding data indicate that GADD45γ suppression is a poor prognostic factor in patients with HCC and may help predict sorafenib efficacy in HCC.
    문서 타입:
    Reference
    카탈로그 번호:
    17-371
    제품명:
    EZ-ChIP™
  • Growth arrest and DNA-damage-inducible, beta (GADD45b)-mediated DNA demethylation in major psychosis. 22048458

    Aberrant neocortical DNA methylation has been suggested to be a pathophysiological contributor to psychotic disorders. Recently, a growth arrest and DNA-damage-inducible, beta (GADD45b) protein-coordinated DNA demethylation pathway, utilizing cytidine deaminases and thymidine glycosylases, has been identified in the brain. We measured expression of several members of this pathway in parietal cortical samples from the Stanley Foundation Neuropathology Consortium (SFNC) cohort. We find an increase in GADD45b mRNA and protein in patients with psychosis. In immunohistochemistry experiments using samples from the Harvard Brain Tissue Resource Center, we report an increased number of GADD45b-stained cells in prefrontal cortical layers II, III, and V in psychotic patients. Brain-derived neurotrophic factor IX (BDNF IXabcd) was selected as a readout gene to determine the effects of GADD45b expression and promoter binding. We find that there is less GADD45b binding to the BDNF IXabcd promoter in psychotic subjects. Further, there is reduced BDNF IXabcd mRNA expression, and an increase in 5-methylcytosine and 5-hydroxymethylcytosine at its promoter. On the basis of these results, we conclude that GADD45b may be increased in psychosis compensatory to its inability to access gene promoter regions.
    문서 타입:
    Reference
    카탈로그 번호:
    AB1511
  • DNA damage signaling, impairment of cell cycle progression, and apoptosis triggered by 5-ethynyl-2'-deoxyuridine incorporated into DNA. 24115313

    The "click chemistry" approach utilizing 5-ethynyl-2'-deoxyuridine (EdU) as a DNA precursor was recently introduced to assess DNA replication and adapted to flow- and imaging-cytometry. In the present study, we observed that EdU, once incorporated into DNA, induces DNA damage signaling (DDS) such as phosphorylation of ATM on Ser1981, of histone H2AX on Ser139, of p53 on Ser15, and of Chk2 on Thr68. It also perturbs progression of cells through the cell cycle and subsequently induces apoptosis. These effects were observed in non-small cell lung adenocarcinoma A549 as well as in B-cell human lymphoblastoid TK6 and WTK1 cells, differing in the status of p53 (wt versus mutated). After 1 h EdU pulse-labeling, the most affected was cells progression through the S phase subsequent to that at which they had incorporated EdU. This indicates that DNA replication using the template containing incorporated EdU is protracted and triggers DDS. Furthermore, progression of cells having DNA pulse-labeled with EdU led to accumulation of cells in G2 , likely by activating G2 checkpoint. Consistent with the latter was activation of p53 and Chk2. Although a correlation was observed in A549 cells between the degree of EdU incorporation and the extent of γH2AX induction, such correlation was weak in TK6 and WTK1 cells. The degree of perturbation of the cell cycle kinetics by the incorporated EdU was different in the wt p53 TK6 cells as compared to their sister WTK1 cell line having mutated p53. The data are thus consistent with the role of p53 in modulating activation of cell cycle checkpoints in response to impaired DNA replication. The confocal microscopy analysis of the 3D images of cells exposed to EdU for 1 h pulse and then grown for 24 or 48 h revealed an increased number of colocalized γH2AX and p53BP1 foci considered to be markers of DNA double-strand breaks and enlarged nuclei.
    문서 타입:
    Reference
    카탈로그 번호:
    05-636
    제품명:
    Anti-phospho-Histone H2A.X (Ser139) Antibody, clone JBW301
  • DNA damage responses in Drosophila nbs mutants with reduced or altered NBS function. 19395318

    The MRN complex, composed of MRE11, RAD50 and NBS, plays important roles in responding to DNA double-strand breaks (DSBs). In metazoans, functional studies of genes encoding these proteins have been challenging because complete loss-of-function mutations are lethal at the organismal level and because NBS has multiple functions in DNA damage responses. To study functions of Drosophila NBS in DNA damage responses, we used a separation-of-function mutation that causes loss of the forkhead-associated (FHA) domain. Loss of the FHA domain resulted in hypersensitivity to ionizing radiation and defects in gap repair by homologous recombination, but had only a small effect on the DNA damage checkpoint response and did not impair DSB repair by end joining. We also found that heterozygosity for an nbs null mutation caused reduced gap repair and loss of the checkpoint response to low-dose irradiation. These findings shed light on possible sources of the cancer predisposition found in human carriers of NBN mutations.
    문서 타입:
    Reference
    카탈로그 번호:
    06-570
    제품명:
    Anti-phospho-Histone H3 (Ser10) Antibody, Mitosis Marker
  • DNA damage promotes histone deacetylase 4 nuclear localization and repression of G2/M promoters, via p53 C-terminal lysines. 16293626

    Repression of G(2)/M promoters after DNA damage is an active mechanism that requires the p53 tumor suppressor. We have recently found that histone deacetylase 4 (HDAC4) is recruited on NF-Y-dependent repressed promoters. In this report, we describe the relationship between p53 and HDAC4 recruitment following DNA damage using immunofluorescence, chromatin immunoprecipitation, and transfection experiments. HDAC4 shuttles from the cytoplasm into the nucleus, following DNA damage, independently of the activation of p53 and becomes associated with promoters through a p53-dependent mechanism. The C-terminal lysines of p53, which are acetylated and methylated, are required for HDAC4 recruitment and transcriptional repression. Trichostatin treatment, but not HDAC4 functional inactivation, relieves the adriamycin-mediated repression of G(2)/M promoters. Our results indicate that HDAC4 is a component of the DNA damage response and that post-translational modifications of p53 are important for repression of G(2)/M genes.
    문서 타입:
    Reference
    카탈로그 번호:
    Multiple
    제품명:
    Multiple
  • DNA Damage Signaling Is Induced in the Absence of Epstein-Barr Virus (EBV) Lytic DNA Replication and in Response to Expression of ZEBRA. 25950714

    Epstein Barr virus (EBV), like other oncogenic viruses, modulates the activity of cellular DNA damage responses (DDR) during its life cycle. Our aim was to characterize the role of early lytic proteins and viral lytic DNA replication in activation of DNA damage signaling during the EBV lytic cycle. Our data challenge the prevalent hypothesis that activation of DDR pathways during the EBV lytic cycle occurs solely in response to large amounts of exogenous double stranded DNA products generated during lytic viral DNA replication. In immunofluorescence or immunoblot assays, DDR activation markers, specifically phosphorylated ATM (pATM), H2AX (γH2AX), or 53BP1 (p53BP1), were induced in the presence or absence of viral DNA amplification or replication compartments during the EBV lytic cycle. In assays with an ATM inhibitor and DNA damaging reagents in Burkitt lymphoma cell lines, γH2AX induction was necessary for optimal expression of early EBV genes, but not sufficient for lytic reactivation. Studies in lytically reactivated EBV-positive cells in which early EBV proteins, BGLF4, BGLF5, or BALF2, were not expressed showed that these proteins were not necessary for DDR activation during the EBV lytic cycle. Expression of ZEBRA, a viral protein that is necessary for EBV entry into the lytic phase, induced pATM foci and γH2AX independent of other EBV gene products. ZEBRA mutants deficient in DNA binding, Z(R183E) and Z(S186E), did not induce foci of pATM. ZEBRA co-localized with HP1β, a heterochromatin associated protein involved in DNA damage signaling. We propose a model of DDR activation during the EBV lytic cycle in which ZEBRA induces ATM kinase phosphorylation, in a DNA binding dependent manner, to modulate gene expression. ATM and H2AX phosphorylation induced prior to EBV replication may be critical for creating a microenvironment of viral and cellular gene expression that enables lytic cycle progression.
    문서 타입:
    Reference
    카탈로그 번호:
    Multiple
    제품명:
    Multiple
  • DNA damage response is suppressed by the high cyclin-dependent kinase 1 activity in mitotic mammalian cells. 21878640

    DNA damage response (DDR) is vital for genomic stability, and its deficiency is linked to tumorigenesis. Extensive studies in interphase (G(1)-S-G(2)) mammalian cells have revealed the mechanisms of DDR in great detail; however, how mitotic cells respond to DNA damage remains less defined. We report here that a full DDR is suppressed in mitotic mammalian cells until telophase/cytokinesis. Although early DDR markers such as the phosphorylations of ataxia telangiectasia mutated (ATM) and histone H2A.x (H2AX) can be readily detected, the ionizing radiation-induced foci (IRIF) formation of late DDR markers such as breast cancer type 1 susceptibility protein (BRCA1) and p53-binding protein 1 (53BP1) are absent until the telophase/cytokinesis stage. We further showed that the IR-induced ubiquitination cascade around DNA damage sites did not occur in mitotic cells, which explains, at least in part, why BRCA1 and 53BP1 cannot be recruited to the damaged sites. These observations indicate that DDR is suppressed in mitotic cells after the step of γH2AX formation. Not surprisingly, we found that the absence of a full DDR in mitotic cells was associated with the high cyclin-dependent kinase 1 (CDK1) activities. More 53BP1 IRIF could be detected when the irradiated mitotic cells were treated with a CDK1 inhibitor. Further, the activation of CDK5 in interphase cells impedes the formation of 53BP1 IRIF. Together, these results suggest that the DDR is suppressed by the high CDK1 activity in mitotic mammalian cells.
    문서 타입:
    Reference
    카탈로그 번호:
    05-636
    제품명:
    Anti-phospho-Histone H2A.X (Ser139) Antibody, clone JBW301
  • DNA damage recognition in the rat zygote following chronic paternal cyclophosphamide exposure. 17872895

    The detrimental effects of preconceptional paternal exposure to the alkylating anticancer agent, cyclophosphamide, include aberrant epigenetic programming, dysregulated zygotic gene activation, and abnormalities in the offspring that are transmitted to the next generation. The adverse developmental consequences of genomic instabilities transmitted via the spermatozoon emphasize the need to elucidate the mechanisms by which the early embryo recognizes DNA damage in the paternal genome. Little information exists on DNA damage detection in the zygote. We assessed the impact of paternal cyclophosphamide exposure on phosphorylated H2AX (gammaH2AX) and poly(ADP-ribose) polymerase-1(PARP-1), biomarkers of DNA damage, to determine the capacity in the rat zygote to recognize genomic damage and initiate a response to DNA lesions. An amplified biphasic gammaH2AX response was triggered in the paternal pronucleus in zygotes sired by drug-treated males; the maternal genome was not affected. PARP-1 immunoreactivity was substantially elevated in both parental genomes, coincident with the second phase of gammaH2AX induction in embryos sired by cyclophosphamide-exposed spermatozoa. Thus, paternal exposure to a DNA damaging agent rapidly activates signals implemental for DNA damage recognition in the zygote. Inefficient repair of DNA lesions may lead to persistent alterations of the histone code and chromatin integrity, resulting in aberrant embryogenesis. We propose that the response of the early embryo to disturbances in spermatozoal genomic integrity plays a vital role in determining its outcome.
    문서 타입:
    Reference
    카탈로그 번호:
    05-636
    제품명:
    Anti-phospho-Histone H2A.X (Ser139) Antibody, clone JBW301
  • DNA damage response induced by tobacco smoke in normal human bronchial epithelial and A549 pulmonary adenocarcinoma cells assessed by laser scanning cytometry. 19658174

    Cigarette smoke (CS) is a major cause of lung cancer and a contributor to the development of a wide range of other malignancies. There is an acute need to develop a methodology that can rapidly assess the potential carcinogenic properties of the genotoxic agents present in CS. We recently reported that exposure of normal human bronchial epithelial cells (NHBEs) or A549 pulmonary carcinoma cells to CS induces the activation of ATM through its phosphorylation on Ser1981 and phosphorylation of histone H2AX on Ser139 (gammaH2AX) most likely in response to the formation of potentially carcinogenic DNA double-strand breaks (DSBs). To obtain a more complete view of the DNA damage response (DDR) we explored the correlation between ATM activation, H2AX phosphorylation, activation of Chk2 through its phosphorylation on Thr68, and phosphorylation of p53 on Ser15 in NHBE and A549 cell exposed to CS. Multiparameter analysis by laser scanning cytometry made it possible to relate these DDR events, detected immunocytochemically, with cell cycle phase. The CS-dose-dependent induction and increase in the extent of phosphorylation of ATM, Chk2, H2AX, and p53 were seen in both cell types. ATM and Chk2 were phosphorylated approximately 1 h prior to phosphorylation of H2AX and p53. The dephosphorylation of ATM, Chk2, and H2AX was seen after 2 h following CS exposure. The dose-dependency and kinetics of DDR were essentially similar in both cell types, which provide justification for the use of A549 cells in the assessment of genotoxicity of CS in lieu of normal bronchial epithelial cells. The observation that DDR was more pronounced in S-phase cells is consistent with the mechanism of induction of DSBs occurring as a result of collision of replication forks with primary lesions such as DNA adducts that can be caused by CS-generated oxidants. The cytometric assessment of CS-induced DDR provides a means to estimate the genotoxicity of CS and to explore the mechanisms of the response as a function of cell cycle phase and cell type.
    문서 타입:
    Reference
    카탈로그 번호:
    05-740
    제품명:
    Anti-phospho-ATM (Ser1981) Antibody, clone 10H11.E12