Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P16104 (H2AX)
 3,930 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Selenium (Se) compounds, which are the most extensively studied cancer chemopreventive agents, induce apoptotic death of tumor cells. In the current study, we show that selenite-induced apoptosis involves DNA damage. We showed that selenite-induced apoptosis as evidenced by cleavage of poly(ADP-ribose) polymerase was reduced in NIH 3T3 cells treated with ATM small interfering RNA, suggesting the involvement of the DNA damage regulator ATM. Consistent with ATM/ATR involvement, selenite was also shown to stimulate Ser-139 phosphorylation of the ATM/ATR substrate H2AX. Selenite-induced apoptosis was shown to involve DNA topoisomerase II (Top II) as selenite-induced apoptosis was reduced in Top II-deficient HL-60/MX2 cells and in HL-60 cells co-treated with the Top II catalytic inhibitor ICRF-193. Using purified human recombinant Top II, selenite was shown to induce reversible Top II cleavage complexes in vitro. In the aggregate, these results suggest that selenite-induced apoptosis, which involves ATM/ATR and Top II, is likely to be because of DNA damage.
 ...
PMID:DNA damage-mediated apoptosis induced by selenium compounds. 1276 54

BRCA1 is a central component of the DNA damage response mechanism and defects in BRCA1 confer sensitivity to a broad range of DNA damaging agents. BRCA1 is required for homologous recombination and DNA damage-induced S and G(2)/M phase arrest. We show here that BRCA1 is required for ATM- and ATR-dependent phosphorylation of p53, c-Jun, Nbs1 and Chk2 following exposure to ionizing or ultraviolet radiation, respectively, and is also required for ATM phosphorylation of CtIP. In contrast, DNA damage-induced phosphorylation of the histone variant H2AX is independent of BRCA1. We also show that the presence of BRCA1 is dispensable for DNA damage-induced phosphorylation of Rad9, Hus1 and Rad17, and for the relocalization of Rad9 and Hus1. We propose that BRCA1 facilitates the ability of ATM and ATR to phosphorylate downstream substrates that directly influence cell cycle checkpoint arrest and apoptosis, but that BRCA1 is dispensable for the phosphorylation of DNA-associated ATM and ATR substrates.
 ...
PMID:A subset of ATM- and ATR-dependent phosphorylation events requires the BRCA1 protein. 1277

We have developed stable cell lines expressing green fluorescent protein fusion proteins containing polyglutamine repeats of various lengths under tetracycline control. The expression of the expanded (43Q) repeat protein resulted in aggregate formation in a time-dependent fashion. The accumulation of aggregates did not induce apoptosis, although the survival of these cells was critically dependent on the presence of serum and growth factors. However, the expression of 43Q expanded protein strongly activated the ataxia telangiectasia mutated kinase/ATM and Rad3-related kinase (ATM/ATR)-dependent DNA damage response, as shown by selective phosphorylation of ATM substrates. This activation was dependent on 43 CAG protein expression, reversible and sensitive to caffeine and reducing agents. Similarly, we found phosphorylated ATM substrates in fibroblasts from Huntington's disease or SCA-2 patients. Oxidative stress induced accumulation of ATM/ATR phosphorylated protein in HD and SCA-2 patients, but not in normal controls. Furthermore, a significant phosphorylation of H2AX was shown by fibroblasts from patients. We conclude that polyglutamine induces ATM/ATR-dependent DNA damage response through accumulation of reactive oxygen species. ATM activation can be used to monitor the disease in vivo.
 ...
PMID:DNA damage induced by polyglutamine-expanded proteins. 1291 85

We report cytologic and genetic data indicating that telomere dysfunction induces a DNA damage response in mammalian cells. Dysfunctional, uncapped telomeres, created through inhibition of TRF2, became associated with DNA damage response factors, such as 53BP1, gamma-H2AX, Rad17, ATM, and Mre11. We refer to the domain of telomere-associated DNA damage factors as a Telomere Dysfunction-Induced Focus (TIF). The accumulation of 53BP1 on uncapped telomeres was reduced in the presence of the PI3 kinase inhibitors caffeine and wortmannin, which affect ATM, ATR, and DNA-PK. By contrast, Mre11 TIFs were resistant to caffeine, consistent with previous findings on the Mre11 response to ionizing radiation. A-T cells had a diminished 53BP1 TIF response, indicating that the ATM kinase is a major transducer of this pathway. However, in the absence of ATM, TRF2 inhibition still induced TIFs and senescence, pointing to a second ATM-independent pathway. We conclude that the cellular response to telomere dysfunction is governed by proteins that also control the DNA damage response. TIFs represent a new tool for evaluating telomere status in normal and malignant cells suspected of harboring dysfunctional telomeres. Furthermore, induction of TIFs through TRF2 inhibition provides an opportunity to study the DNA damage response within the context of well-defined, physically marked lesions.
 ...
PMID:DNA damage foci at dysfunctional telomeres. 1295 59

Cellular recovery from ionizing radiation (IR)-induced damage involves poly(ADP-ribose) polymerase (PARP-1 and PARP-2) activity, resulting in the induction of a signalling network responsible for the maintenance of genomic integrity. In the present work, a charged particle microbeam delivering 3.2 MeV protons from a Van de Graaff accelerator has been used to locally irradiate mammalian cells. We show the immediate response of PARPs to local irradiation, concomitant with the recruitment of ATM and Rad51 at sites of DNA damage, both proteins being involved in DNA strand break repair. We found a co-localization but no connection between two DNA damage-dependent post-translational modifications, namely poly(ADP-ribosyl)ation of nuclear proteins and phosphorylation of histone H2AX. Both of them, however, should be considered and used as bona fide immediate sensitive markers of IR damage in living cells. This technique thus provides a powerful approach aimed at understanding the interactions between the signals originating from sites of DNA damage and the subsequent activation of DNA strand break repair mechanisms
 ...
PMID:Local DNA damage by proton microbeam irradiation induces poly(ADP-ribose) synthesis in mammalian cells. 1296 Apr 8

Histone H2AX is phosphorylated on Ser-139 by ATM kinase in response to damage that induces dsDNA breaks. Immunocytochemical detection of phosphorylated H2AX (gammaH2AX), thus, reveals the presence of dsDNA breaks in chromatin. Multiparameter cytometry was presently used to correlate the appearance of gammaH2AX with: a. cell cycle phase; b. caspase-3 activation; and c. apoptosis-associated DNA fragmentation in individual human leukemic HL-60 cells treated with the DNA topoisomerase I (topo1) inhibitors topotecan (TPT) and camptothecin (CPT) or with the topo2 inhibitor mitoxantrone (MTX). In response to TPT or CPT maximal increase of gammaH2AX immunofluorescence was seen in S-phase cells by 90 min. In contrast, following MTX treatment the maximal rise of gammaH2AX was detected at 2 h in G1 cells and the cell cycle phase specificity was much less apparent. A linear relationship between the drug concentration and increase of gammaH2AX immunofluorescence was seen only up to 200 nM TPT; a decline in gammaH2AX was apparent at a concentration range between 0.4 and 1.6 microM TPT. Thus, the intensity of gammaH2AX immunofluorescence, as a marker of cell survival following TPT treatment, can be used only within a limited range of drug concentration. Following treatment with TPT, CPT or MTX the peak of H2AX phosphorylation preceded caspase-3 activation and the appearance of apoptosis-associated DNA fragmentation, both selective to S-phase cells. Progression of apoptosis was paralleled by a decrease in gammaH2AX immunofluorescence. The data also indicate that regardless whether treated with inhibitors of topo1 or topo2, at comparable levels of dsDNA breaks, the cells replicating DNA have a higher proclivity to undergo apoptosis compared to G1 or G2/M cells.
 ...
PMID:DNA damage induced by DNA topoisomerase I- and topoisomerase II-inhibitors detected by histone H2AX phosphorylation in relation to the cell cycle phase and apoptosis. 1450 78

Cell cycle checkpoints that monitor DNA damage and spindle assembly are essential for the maintenance of genetic integrity, and drugs that target these checkpoints are important chemotherapeutic agents. We have examined how cells respond to DNA damage while the spindle-assembly checkpoint is activated. Single cell electrophoresis and phosphorylation of histone H2AX indicated that several chemotherapeutic agents could induce DNA damage during mitotic block. DNA damage during mitotic block triggered CDC2 inactivation, histone H3 dephosphorylation, and chromosome decondensation. Cells did not progress into G1 but seemed to retract to a G2-like state containing 4N DNA content, with stabilized cyclin A and cyclin B1 binding to Thr14/Tyr15-phosphorylated CDC2. The loss of mitotic cells was not due to cell death because there was no discernible effect on caspase-3 activation, DNA fragmentation, or viability. Extensive DNA damage during mitotic block inactivated cyclin B1-CDC2 and prevented G1 entry when the block was removed. The mitotic DNA damage responses were independent of p53 and pRb, but they were dependent on ATM. CDC25A that accumulated during mitosis was rapidly destroyed after DNA damage in an ATM-dependent manner. Ectopic expression of CDC25A or nonphosphorylatable CDC2 effectively inhibited the dephosphorylation of histone H3 after DNA damage. Hence, although spindle disruption and DNA damage provide conflicting signals to regulate CDC2, the negative regulation by the DNA damage checkpoint could overcome the positive regulation by the spindle-assembly checkpoint.
 ...
PMID:DNA damage during the spindle-assembly checkpoint degrades CDC25A, inhibits cyclin-CDC2 complexes, and reverses cells to interphase. 1451 13

NFBD1/MDC1 (mediator of DNA damage checkpoint 1) is a nuclear factor with an amino-terminal FHA (forkhead-associated) domain and a tandem repeat of BRCT (breast cancer susceptibility gene-1 carboxyl terminus) domains. We have previously shown that NFBD1 is an early participant in DNA damage signaling pathways and that ionizing radiation-induced nuclear foci (IRIF) of NFBD1 colocalize with several DNA checkpoint signaling and repair factors. We report here that NFBD1 physically associates with ATM, p53, components of the MRE11-RAD50-NBS1 (MRN) complex, and gamma-H2AX. An overexpressed FHA domain-containing fragment of NFBD1 binds to endogenous NFBD1 and components of the MRN complex, but not to gamma-H2AX. This fragment interferes with IRIF formation by endogenous NFBD1, MRE11, or NBS1. A BRCT domain-containing fragment of NFBD1 binds to gamma-H2AX and 53BP1, but not to components of the MRN complex, and abolishes IRIF formation by NFBD1, MRE11, NBS1, 53BP1, CHK2 phospho-T68, gamma-H2AX, and possible ATM/ATR substrates recognized by anti-phospho-SQ/TQ antibody. These results suggest that NFBD1 is an ATM/ATR-dependent organizer that recruits DNA checkpoint signaling and repair proteins to the sites of DNA damage.
 ...
PMID:NFBD1/MDC1 regulates ionizing radiation-induced focus formation by DNA checkpoint signaling and repair factors. 1451 63

We used a proteomic approach to identify phosphopeptide-binding modules mediating signal transduction events in the DNA damage response pathway. Using a library of partially degenerate phosphopeptides, we identified tandem BRCT (BRCA1 carboxyl-terminal) domains in PTIP (Pax transactivation domain-interacting protein) and in BRCA1 as phosphoserine- or phosphothreonine-specific binding modules that recognize substrates phosphorylated by the kinases ATM (ataxia telangiectasia-mutated) and ATR (ataxia telangiectasia- and RAD3-related) in response to gamma-irradiation. PTIP tandem BRCT domains are responsible for phosphorylation-dependent protein localization into 53BP1- and phospho-H2AX (gamma-H2AX)-containing nuclear foci, a marker of DNA damage. These findings provide a molecular basis for BRCT domain function in the DNA damage response and may help to explain why the BRCA1 BRCT domain mutation Met1775 --> Arg, which fails to bind phosphopeptides, predisposes women to breast and ovarian cancer.
 ...
PMID:BRCT repeats as phosphopeptide-binding modules involved in protein targeting. 1457 10

Severe levels of hypoxia (oxygen concentrations of less that 0.02%) have been shown to induce a rapid S-phase arrest. The mechanism behind hypoxia-induced S-phase arrest is unclear, we show here that it was not mediated by a shortage of nucleosides and was not dependent on p53, p21 or Hif 1alpha status. The drugs aphidicolin and hydroxyurea both induce rapid replication arrest and have been used throughout the literature to study the ATR-mediated response to stalled replication. We have shown previously that hypoxia induces ATR-dependent phosphorylation of p53, Chk1 and histone H2AX. Using comet-assays to detect DNA-damage we found that both aphidicolin and hydroxyurea induced significant levels of DNA-damage while hypoxia did not. Here we show that like aphidicolin and hydroxyurea, hypoxia induces phosphorylation of Nbs1 at serine 343 and Rad17 serine 645. Hypoxia-dependent phosphorylation of Nbs1 and Rad17 was ATM-independent and therefore likely to be a result of the ATR kinase activity. In contrast, p53 was phosphorylated differentially in response to the three treatments considered here. p53 was phosphorylated at serine 15 in response to all three treatments but was only phosphorylated at serine 20 in response to the drug treatments. We propose that treatment with either aphidicolin or hydroxyurea leads to not only replication arrest but also DNA-damage and therefore both ATM and ATR-mediated signaling. In contrast replication arrest induced by severe hypoxia is sensed exclusively through ATR, with ATM only having a role to play after re-oxygenation.
 ...
PMID:Comparison of hypoxia-induced replication arrest with hydroxyurea and aphidicolin-induced arrest. 1464 37


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>