scholarly journals DNA Methylation Inhibitor 5-Aza-2′-Deoxycytidine Induces Reversible Genome-Wide DNA Damage That Is Distinctly Influenced by DNA Methyltransferases 1 and 3B

2007 ◽  
Vol 28 (2) ◽  
pp. 752-771 ◽  
Author(s):  
Stela S. Palii ◽  
Beth O. Van Emburgh ◽  
Umesh T. Sankpal ◽  
Kevin D. Brown ◽  
Keith D. Robertson
Keyword(s):  
Dna Methylation ◽  
Dna Damage ◽  
Tumor Cells ◽  
Dna Damage Response ◽  
Dna Methyltransferases ◽  
Dependent Manner ◽  
Antitumor Effects ◽  
Checkpoint Kinase ◽  
Genome Wide ◽  
Damage Response

ABSTRACT Genome-wide DNA methylation patterns are frequently deregulated in cancer. There is considerable interest in targeting the methylation machinery in tumor cells using nucleoside analogs of cytosine, such as 5-aza-2′-deoxycytidine (5-azadC). 5-azadC exerts its antitumor effects by reactivation of aberrantly hypermethylated growth regulatory genes and cytoxicity resulting from DNA damage. We sought to better characterize the DNA damage response of tumor cells to 5-azadC and the role of DNA methyltransferases 1 and 3B (DNMT1 and DNMT3B, respectively) in modulating this process. We demonstrate that 5-azadC treatment results in growth inhibition and G2 arrest—hallmarks of a DNA damage response. 5-azadC treatment led to formation of DNA double-strand breaks, as monitored by formation of γ-H2AX foci and comet assay, in an ATM (ataxia-telangiectasia mutated)-dependent manner, and this damage was repaired following drug removal. Further analysis revealed activation of key strand break repair proteins including ATM, ATR (ATM-Rad3-related), checkpoint kinase 1 (CHK1), BRCA1, NBS1, and RAD51 by Western blotting and immunofluorescence. Significantly, DNMT1-deficient cells demonstrated profound defects in these responses, including complete lack of γ-H2AX induction and blunted p53 and CHK1 activation, while DNMT3B-deficient cells generally showed mild defects. We identified a novel interaction between DNMT1 and checkpoint kinase CHK1 and showed that the defective damage response in DNMT1-deficient cells is at least in part due to altered CHK1 subcellular localization. This study therefore greatly enhances our understanding of the mechanisms underlying 5-azadC cytotoxicity and reveals novel functions for DNMT1 as a component of the cellular response to DNA damage, which may help optimize patient responses to this agent in the future.

scholarly journals Genome-wide screen of human bromodomain-containing proteins identifies Cecr2 as a novel DNA damage response protein

2012 ◽  
Vol 34 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Seul-Ki Lee ◽  
Eun-Jung Park ◽  
Han-Sae Lee ◽  
Ye Seul Lee ◽  
Jongbum Kwon
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Genome Wide ◽  
Damage Response

scholarly journals ATF4-Mediated Upregulation of REDD1 and Sestrin2 Suppresses mTORC1 Activity during Prolonged Leucine Deprivation

2019 ◽  
Vol 150 (5) ◽  
pp. 1022-1030 ◽  
Author(s):  
Dandan Xu ◽  
Weiwei Dai ◽  
Lydia Kutzler ◽  
Holly A Lacko ◽  
Leonard S Jefferson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dna Damage ◽  
Amino Acid ◽  
Protein Kinase ◽  
Dna Damage Response ◽  
Dependent Manner ◽  
Mouse Embryo Fibroblasts ◽  
Damage Response ◽  
Mtorc1 Activation ◽  
In Cells

ABSTRACT Background The protein kinase target of rapamycin (mTOR) in complex 1 (mTORC1) is activated by amino acids and in turn upregulates anabolic processes. Under nutrient-deficient conditions, e.g., amino acid insufficiency, mTORC1 activity is suppressed and autophagy is activated. Intralysosomal amino acids generated by autophagy reactivate mTORC1. However, sustained mTORC1 activation during periods of nutrient insufficiency would likely be detrimental to cellular homeostasis. Thus, mechanisms must exist to prevent amino acids released by autophagy from reactivating the kinase. Objective The objective of the present study was to test whether mTORC1 activity is inhibited during prolonged leucine deprivation through ATF4-dependent upregulation of the mTORC1 suppressors regulated in development and DNA damage response 1 (REDD1) and Sestrin2. Methods Mice (8 wk old; C57Bl/6 × 129SvEV) were food deprived (FD) overnight and one-half were refed the next morning. Mouse embryo fibroblasts (MEFs) deficient in ATF4, REDD1, and/or Sestrin2 were deprived of leucine for 0–16 h. mTORC1 activity and ATF4, REDD1, and Sestrin2 expression were assessed in liver and cell lysates. Results Refeeding FD mice resulted in activation of mTORC1 in association with suppressed expression of both REDD1 and Sestrin2 in the liver. In cells in culture, mTORC1 exhibited a triphasic response to leucine deprivation, with an initial suppression followed by a transient reactivation from 2 to 4 h and a subsequent resuppression after 8 h. Resuppression occurred concomitantly with upregulated expression of ATF4, REDD1, and Sestrin2. However, in cells lacking ATF4, neither REDD1 nor Sestrin2 expression was upregulated by leucine deprivation, and resuppression of mTORC1 was absent. Moreover, in cells lacking either REDD1 or Sestrin2, mTORC1 resuppression was attenuated, and in cells lacking both proteins resuppression was further blunted. Conclusions The results suggest that leucine deprivation upregulates expression of both REDD1 and Sestrin2 in an ATF4-dependent manner, and that upregulated expression of both proteins is involved in resuppression of mTORC1 during prolonged leucine deprivation.

scholarly journals Ribosomal protein L6 (RPL6) is recruited to DNA damage sites in a poly(ADP-ribose) polymerase–dependent manner and regulates the DNA damage response

2018 ◽  
Vol 294 (8) ◽  
pp. 2827-2838 ◽  
Author(s):  
Chuanzhen Yang ◽  
Weicheng Zang ◽  
Yapeng Ji ◽  
Tingting Li ◽  
Yongfeng Yang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ribosomal Protein ◽  
Dna Damage Response ◽  
Dependent Manner ◽  
Damage Response

scholarly journals Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells

2013 ◽  
Vol 288 (23) ◽  
pp. 16212-16224 ◽  
Author(s):  
Elvira Crescenzi ◽  
Zelinda Raia ◽  
Francesco Pacifico ◽  
Stefano Mellone ◽  
Fortunato Moscato ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Cells ◽  
Dna Damage Response ◽  
Critical Role ◽  
Wild Type ◽  
Down Regulation ◽  
Senescent Phenotype ◽  
Response To Chemotherapy ◽  
Damage Response ◽  
Wild Type P53

Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype.

Coordinated Chromatin-Association of Fanconi Anemia Network Proteins Requires Replication-Coupled DNA Damage Recognition.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 723-723
Author(s):  
Alexandra Sobeck ◽  
Stacie Stone ◽  
Bendert deGraaf ◽  
Vincenzo Costanzo ◽  
Johan deWinter ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Response ◽  
Fanconi Anemia ◽  
Bone Marrow Failure ◽  
S Phase ◽  
Dependent Manner ◽  
Core Complex ◽  
Damage Response ◽  
Crosslinking Agents

Abstract Fanconi anemia (FA) is a genetic disorder characterized by hypersensitivity to DNA crosslinking agents and diverse clinical symptoms, including developmental anomalies, progressive bone marrow failure, and predisposition to leukemias and other cancers. FA is genetically heterogeneous, resulting from mutations in any of at least eleven different genes. The FA proteins function together in a pathway composed of a mulitprotein core complex that is required to trigger the DNA-damage dependent activation of the downstream FA protein, FANCD2. This activation is thought to be the key step in a DNA damage response that functionally links FA proteins to major breast cancer susceptibility proteins BRCA1 and BRCA2 (BRCA2 is FA gene FANCD1). The essential function of the FA proteins is unknown, but current models suggest that FA proteins function at the interface between cell cycle checkpoints, DNA repair and DNA replication, and are likely to play roles in the DNA damage response during S phase. To provide a platform for dissecting the key functional events during S-phase, we developed cell-free assays for FA proteins based on replicating extracts from Xenopus eggs. We identified the Xenopus homologs of human FANCD2 (xFANCD2) and several of the FA core complex proteins (xCCPs), and biochemically characterized these proteins in replicating cell-free extracts. We found that xCCPs and a modified isoform of xFANCD2 become associated with chromatin during normal and disrupted DNA replication. Blocking initiation of replication with geminin demonstrated that association of xCCPs and xFANCD2 with chromatin occurs in a strictly replication-dependent manner that is enhanced following DNA damage by crosslinking agents or by addition of aphidicolin, an inhibitor of replicative DNA polymerases. In addition, chromatin binding of xFANCD2, but not xBRCA2, is abrogated when xFANCA is quantitatively depleted from replicating extracts suggesting that xFANCA promotes the loading of xFANCD2 on chromatin. The chromatin-association of xFANCD2 and xCCPs is diminished in the presence of caffeine, an inhibitor of checkpoint kinases. Taken together, our data suggest a model in which the ordered loading of FA proteins on chromatin is required for processing a subset of DNA replication-blocking lesions that are resolved during late stages of replication.

M2, a novel anthracenedione, elicits a potent DNA damage response that can be subverted through checkpoint kinase inhibition to generate mitotic catastrophe

2011 ◽  
Vol 82 (11) ◽  
pp. 1604-1618 ◽  
Author(s):  
Benny J. Evison ◽  
Mile Pastuovic ◽  
Rebecca A. Bilardi ◽  
Robert A. Forrest ◽  
Paul P. Pumuye ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Mitotic Catastrophe ◽  
Kinase Inhibition ◽  
Checkpoint Kinase ◽  
Damage Response

scholarly journals ATM regulates a DNA damage response posttranscriptional RNA operon in lymphocytes

Blood ◽  
2011 ◽  
Vol 117 (8) ◽  
pp. 2441-2450 ◽  
Author(s):  
Krystyna Mazan-Mamczarz ◽  
Patrick R. Hagner ◽  
Yongqing Zhang ◽  
Bojie Dai ◽  
Elin Lehrmann ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Ataxia Telangiectasia ◽  
Rna Binding ◽  
Critical Role ◽  
Cell Cycle Checkpoints ◽  
Dependent Manner ◽  
Damage Response ◽  
Multiple Cell

Abstract Maintenance of genomic stability depends on the DNA damage response, a biologic barrier in early stages of cancer development. Failure of this response results in genomic instability and high predisposition toward lymphoma, as seen in patients with ataxia-telangiectasia mutated (ATM) dysfunction. ATM activates multiple cell-cycle checkpoints and DNA repair after DNA damage, but its influence on posttranscriptional gene expression has not been examined on a global level. We show that ionizing radiation modulates the dynamic association of the RNA-binding protein HuR with target mRNAs in an ATM-dependent manner, potentially coordinating the genotoxic response as an RNA operon. Pharmacologic ATM inhibition and use of ATM-null cells revealed a critical role for ATM in this process. Numerous mRNAs encoding cancer-related proteins were differentially associated with HuR depending on the functional state of ATM, in turn affecting expression of encoded proteins. The findings presented here reveal a previously unidentified role of ATM in controlling gene expression posttranscriptionally. Dysregulation of this DNA damage response RNA operon is probably relevant to lymphoma development in ataxia-telangiectasia persons. These novel RNA regulatory modules and genetic networks provide critical insight into the function of ATM in oncogenesis.

Sign in / Sign up

Export Citation Format

Share Document