Activation of and dependence on ataxia telangiectasia mutated kinase in PTEN-deficient tumor cells.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 10553-10553
Author(s):  
Nuala McCabe ◽  
Steven M. Walker ◽  
Nicolas Goffard ◽  
Katarina Wikstrom ◽  
Caroline Greenan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Oxidative Stress ◽  
Ovarian Cancer ◽  
Dna Damage ◽  
Ataxia Telangiectasia ◽  
Clustering Analysis ◽  
Gene List ◽  
Hierarchical Clustering Analysis ◽  
Wild Type ◽  
Ataxia Telangiectasia Mutated

10553 Background: Loss of PTEN function has been widely reported to cause up-regulation of the PI3K/AKT signalling pathway resulting in increased cell growth, proliferation and survival. More recently it has been reported that PTEN null cells demonstrate genomic instability and have increased production of reactive oxygen species (ROS) and oxidative stress induced DNA damage. Ataxia Telangiectasia Mutated (ATM) is the primary response kinase, which responds to stalled DNA replication and DNA double strand breaks due to oxidative DNA damage. Methods: A metagene representing ATM activation was generated from cell line data and used to perform hierarchical clustering analysis of public DNA microarray profiling datasets of breast cancer, ovarian cancer and glioblastoma with known PTEN IHC/mutation status. Furthermore, we ask if ATM activation may be therapeutically exploited in PTEN null tumours using ATM specific siRNA and compounds in 2 PTEN isogenic cell line model systems. Results: We show that PTEN null cells have elevated levels of ROS, DNA damage and have endogenous activation of ATM, an enzyme important in responding to DNA damage resulting from oxidative stress. We hypothesised that PTEN deficient tumours may rely on ATM enzyme for survival. To investigate this we generated a 189-gene list representing ATM activation and used this to perform hierarchical clustering analysis of a breast cancer DNA microarray dataset. This list was able to significantly cluster tumours with known loss of PTEN expression (p=0.004). Furthermore, this gene list was able to segregate PTEN null/mutant tumours from PTEN wild-type tumours in 2 independent datasets of glioblastoma and ovarian cancer (p=0.015 and p=0.012). In addition, we found that inhibition of ATM using the selective inhibitor KU-55933 caused DNA damage, cell cycle arrest and apoptosis specifically in PTEN deficient cells when compared to PTEN wild-type cells. Conclusions: These observations suggest that ATM may represent a therapeutic target in PTEN deficient tumours and furthermore ATM activation may be the basis of a biomarker of PTEN status in human cancers.

scholarly journals Ataxia Telangiectasia Mutated Protein Kinase: A Potential Master Puppeteer of Oxidative Stress-Induced Metabolic Recycling

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Marguerite Blignaut ◽  
Sarah Harries ◽  
Amanda Lochner ◽  
Barbara Huisamen
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Protein Kinase ◽  
Ataxia Telangiectasia ◽  
Regulatory Protein ◽  
Protein Aggregates ◽  
Ataxia Telangiectasia Mutated ◽  
Damage Repair ◽  
Ataxia Telangiectasia Mutated Protein

Ataxia Telangiectasia Mutated protein kinase (ATM) has recently come to the fore as a regulatory protein fulfilling many roles in the fine balancing act of metabolic homeostasis. Best known for its role as a transducer of DNA damage repair, the activity of ATM in the cytosol is enjoying increasing attention, where it plays a central role in general cellular recycling (macroautophagy) as well as the targeted clearance (selective autophagy) of damaged mitochondria and peroxisomes in response to oxidative stress, independently of the DNA damage response. The importance of ATM activation by oxidative stress has also recently been highlighted in the clearance of protein aggregates, where the expression of a functional ATM construct that cannot be activated by oxidative stress resulted in widespread accumulation of protein aggregates. This review will discuss the role of ATM in general autophagy, mitophagy, and pexophagy as well as aggrephagy and crosstalk between oxidative stress as an activator of ATM and its potential role as a master regulator of these processes.

scholarly journals DNA Damage during Reoxygenation Elicits a Chk2-Dependent Checkpoint Response

2006 ◽  
Vol 26 (5) ◽  
pp. 1598-1609 ◽  
Author(s):  
Rachel A. Freiberg ◽  
Ester M. Hammond ◽  
Mary Jo Dorie ◽  
Scott M. Welford ◽  
Amato J. Giaccia
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Tumor Cell ◽  
Solid Tumors ◽  
Ataxia Telangiectasia ◽  
Clonogenic Survival ◽  
Ataxia Telangiectasia Mutated ◽  
Checkpoint Response ◽  
Opening And Closing ◽  
And Oxidative Stress

ABSTRACT Due to the abnormal vasculature of solid tumors, tumor cell oxygenation can change rapidly with the opening and closing of blood vessels, leading to the activation of both hypoxic response pathways and oxidative stress pathways upon reoxygenation. Here, we report that ataxia telangiectasia mutated-dependent phosphorylation and activation of Chk2 occur in the absence of DNA damage during hypoxia and are maintained during reoxygenation in response to DNA damage. Our studies involving oxidative damage show that Chk2 is required for G2 arrest. Following exposure to both hypoxia and reoxygenation, Chk2−/− cells exhibit an attenuated G2 arrest, increased apoptosis, reduced clonogenic survival, and deficient phosphorylation of downstream targets. These studies indicate that the combination of hypoxia and reoxygenation results in a G2 checkpoint response that is dependent on the tumor suppressor Chk2 and that this checkpoint response is essential for tumor cell adaptation to changes that result from the cycling nature of hypoxia and reoxygenation found in solid tumors.

scholarly journals Exposure of the cytoplasm to low-dose X-rays modifies ataxia telangiectasia mutated-mediated DNA damage responses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Munetoshi Maeda ◽  
Masanori Tomita ◽  
Mika Maeda ◽  
Hideki Matsumoto ◽  
Noriko Usami ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Ataxia Telangiectasia ◽  
Kinase Inhibitor ◽  
Surrogate Marker ◽  
X Rays ◽  
Ataxia Telangiectasia Mutated ◽  
Whole Cell ◽  
X Ray ◽  
Dna Damage Responses

AbstractWe recently showed that when a low X-ray dose is used, cell death is enhanced in nucleus-irradiated compared with whole-cell-irradiated cells; however, the role of the cytoplasm remains unclear. Here, we show changes in the DNA damage responses with or without X-ray microbeam irradiation of the cytoplasm. Phosphorylated histone H2AX foci, a surrogate marker for DNA double-strand breaks, in V79 and WI-38 cells are not observed in nucleus irradiations at ≤ 2 Gy, whereas they are observed in whole-cell irradiations. Addition of an ataxia telangiectasia mutated (ATM) kinase inhibitor to whole-cell irradiations suppresses foci formation at ≤ 2 Gy. ABL1 and p73 expression is upregulated following nucleus irradiation, suggesting the induction of p73-dependent cell death. Furthermore, CDKN1A (p21) is upregulated following whole-cell irradiation, indicating the induction of cell cycle arrest. These data reveal that cytoplasmic radioresponses modify ATM-mediated DNA damage responses and determine the fate of cells irradiated at low doses.

scholarly journals Escherichia coli MutM Suppresses Illegitimate Recombination Induced by Oxidative Stress

Genetics ◽  
1999 ◽  
Vol 151 (2) ◽  
pp. 439-446 ◽  
Author(s):  
Masaaki Onda ◽  
Katsuhiro Hanada ◽  
Hirokazu Kawachi ◽  
Hideo Ikeda
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Double Strand Breaks ◽  
Illegitimate Recombination ◽  
Recombination Analysis ◽  
Wild Type ◽  
Strand Breaks ◽  
In The Wild

Abstract DNA damage by oxidative stress is one of the causes of mutagenesis. However, whether or not DNA damage induces illegitimate recombination has not been determined. To study the effect of oxidative stress on illegitimate recombination, we examined the frequency of λbio transducing phage in the presence of hydrogen peroxide and found that this reagent enhances illegitimate recombination. To clarify the types of illegitimate recombination, we examined the effect of mutations in mutM and related genes on the process. The frequency of λbio transducing phage was 5- to 12-fold higher in the mutM mutant than in the wild type, while the frequency in the mutY and mutT mutants was comparable to that of the wild type. Because 7,8-dihydro-8-oxoguanine (8-oxoG) and formamido pyrimidine (Fapy) lesions can be removed from DNA by MutM protein, these lesions are thought to induce illegitimate recombination. Analysis of recombination junctions showed that the recombination at Hotspot I accounts for 22 or 4% of total λbio transducing phages in the wild type or in the mutM mutant, respectively. The preferential increase of recombination at nonhotspot sites with hydrogen peroxide in the mutM mutant was discussed on the basis of a new model, in which 8-oxoG and/or Fapy residues may introduce double-strand breaks into DNA.

scholarly journals Enhanced Phosphorylation of Transcription Factor Sp1 in Response to Herpes Simplex Virus Type 1 Infection Is Dependent on the Ataxia Telangiectasia-Mutated Protein

2007 ◽  
Vol 81 (18) ◽  
pp. 9653-9664 ◽  
Author(s):  
Satoko Iwahori ◽  
Noriko Shirata ◽  
Yasushi Kawaguchi ◽  
Sandra K. Weller ◽  
Yoshitaka Sato ◽  
...  
Keyword(s):  
Dna Damage ◽  
Transcription Factor ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Herpes Simplex Virus Type ◽  
Ataxia Telangiectasia ◽  
Ataxia Telangiectasia Mutated ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT The ataxia telangiectasia-mutated (ATM) protein, a member of the related phosphatidylinositol 3-like kinase family encoded by a gene responsible for the human genetic disorder ataxia telangiectasia, regulates cellular responses to DNA damage and viral infection. It has been previously reported that herpes simplex virus type 1 (HSV-1) infection induces activation of protein kinase activity of ATM and hyperphosphorylation of transcription factor, Sp1. We show that ATM is intimately involved in Sp1 hyperphosphorylation during HSV-1 infection rather than individual HSV-1-encoded protein kinases. In ATM-deficient cells or cells silenced for ATM expression by short hairpin RNA targeting, hyperphosphorylation of Sp1 was prevented even as HSV-1 infection progressed. Mutational analysis of putative ATM phosphorylation sites on Sp1 and immunoblot analysis with phosphopeptide-specific Sp1 antibodies clarified that at least Ser-56 and Ser-101 residues on Sp1 became phosphorylated upon HSV-1 infection. Serine-to-alanine mutations at both sites on Sp1 considerably abolished hyperphosphorylation of Sp1 upon infection. Although ATM phosphorylated Ser-101 but not Ser-56 on Sp1 in vitro, phosphorylation of Sp1 at both sites was not detected at all upon infection in ATM-deficient cells, suggesting that cellular kinase(s) activated by ATM could be involved in phosphorylation at Ser-56. Upon viral infection, Sp1-dependent transcription in ATM expression-silenced cells was almost the same as that in ATM-intact cells, suggesting that ATM-dependent phosphorylation of Sp1 might hardly affect its transcriptional activity during the HSV-1 infection. ATM-dependent Sp1 phosphorylation appears to be a global response to various DNA damage stress including viral DNA replication.

scholarly journals Tethering DNA Damage Checkpoint Mediator Proteins Topoisomerase IIβ-binding Protein 1 (TopBP1) and Claspin to DNA Activates Ataxia-Telangiectasia Mutated and RAD3-related (ATR) Phosphorylation of Checkpoint Kinase 1 (Chk1)

2011 ◽  
Vol 286 (22) ◽  
pp. 19229-19236 ◽  
Author(s):  
Laura A. Lindsey-Boltz ◽  
Aziz Sancar
Keyword(s):  
Dna Damage ◽  
Ataxia Telangiectasia ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Effector Proteins ◽  
Ataxia Telangiectasia Mutated ◽  
Checkpoint Kinase ◽  
Atr Kinase

The ataxia-telangiectasia mutated and RAD3-related (ATR) kinase initiates DNA damage signaling pathways in human cells after DNA damage such as that induced upon exposure to ultraviolet light by phosphorylating many effector proteins including the checkpoint kinase Chk1. The conventional view of ATR activation involves a universal signal consisting of genomic regions of replication protein A-covered single-stranded DNA. However, there are some indications that the ATR-mediated checkpoint can be activated by other mechanisms. Here, using the well defined Escherichia coli lac repressor/operator system, we have found that directly tethering the ATR activator topoisomerase IIβ-binding protein 1 (TopBP1) to DNA is sufficient to induce ATR phosphorylation of Chk1 in an in vitro system as well as in vivo in mammalian cells. In addition, we find synergistic activation of ATR phosphorylation of Chk1 when the mediator protein Claspin is also tethered to the DNA with TopBP1. Together, these findings indicate that crowding of checkpoint mediator proteins on DNA is sufficient to activate the ATR kinase.

scholarly journals Ataxia Telangiectasia Mutated Kinase Mediates NF-κB Serine 276 Phosphorylation and Interferon Expression via the IRF7-RIG-I Amplification Loop in Paramyxovirus Infection

2014 ◽  
Vol 89 (5) ◽  
pp. 2628-2642 ◽  
Author(s):  
Ling Fang ◽  
Sanjeev Choudhary ◽  
Bing Tian ◽  
Istvan Boldogh ◽  
Chunying Yang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Retinoic Acid ◽  
Dna Damage Response ◽  
Type I ◽  
Regulatory Factor ◽  
Ataxia Telangiectasia Mutated ◽  
Damage Response ◽  
Amplification Loop ◽  
Inducible Gene

ABSTRACTRespiratory syncytial virus (RSV) is a primary etiological agent of childhood lower respiratory tract disease. Molecular patterns induced by active infection trigger a coordinated retinoic acid-inducible gene I (RIG-I)-Toll-like receptor (TLR) signaling response to induce inflammatory cytokines and antiviral mucosal interferons. Recently, we discovered a nuclear oxidative stress-sensitive pathway mediated by the DNA damage response protein, ataxia telangiectasia mutated (ATM), in cytokine-induced NF-κB/RelA Ser 276 phosphorylation. Here we observe that ATM silencing results in enhanced single-strand RNA (ssRNA) replication of RSVand Sendai virus, due to decreased expression and secretion of type I and III interferons (IFNs), despite maintenance of IFN regulatory factor 3 (IRF3)-dependent IFN-stimulated genes (ISGs). In addition to enhanced oxidative stress, RSV replication enhances foci of phosphorylated histone 2AX variant (γH2AX), Ser 1981 phosphorylation of ATM, and IKKγ/NEMO-dependent ATM nuclear export, indicating activation of the DNA damage response. ATM-deficient cells show defective RSV-induced mitogen and stress-activated kinase 1 (MSK-1) Ser 376 phosphorylation and reduced RelA Ser 276 phosphorylation, whose formation is required for IRF7 expression. We observe that RelA inducibly binds the native IFN regulatory factor 7 (IRF7) promoter in an ATM-dependent manner, and IRF7 inducibly binds to the endogenous retinoic acid-inducible gene I (RIG-I) promoter. Ectopic IRF7 expression restores RIG-I expression and type I/III IFN expression in ATM-silenced cells. We conclude that paramyxoviruses trigger the DNA damage response, a pathway required for MSK1 activation of phospho Ser 276 RelA formation to trigger the IRF7-RIG-I amplification loop necessary for mucosal IFN production. These data provide the molecular pathogenesis for defects in the cellular innate immunity of patients with homozygous ATM mutations.IMPORTANCERNA virus infections trigger cellular response pathways to limit spread to adjacent tissues. This “innate immune response” is mediated by germ line-encoded pattern recognition receptors that trigger activation of two, largely independent, intracellular NF-κB and IRF3 transcription factors. Downstream, expression of protective antiviral interferons is amplified by positive-feedback loops mediated by inducible interferon regulatory factors (IRFs) and retinoic acid inducible gene (RIG-I). Our results indicate that a nuclear oxidative stress- and DNA damage-sensing factor, ATM, is required to mediate a cross talk pathway between NF-κB and IRF7 through mediating phosphorylation of NF-κB. Our studies provide further information about the defects in cellular and innate immunity in patients with inherited ATM mutations.

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