The P2X7 receptor is a target of p53 and regulates haematopoiesis following radiation-induced genotoxic stress

Head and neck cancer treatments typically involve a combination of surgery and radiotherapy, often leading to collateral damage to nearby tissues causing unwanted side effects. Radiation damage to salivary glands frequently leads to irreversible dysfunction by poorly understood mechanisms. The P2X7 receptor (P2X7R) is a ligand-gated ion channel activated by extracellular ATP released from damaged cells as “danger signals.” P2X7R activation initiates apoptosis and is involved in numerous inflammatory disorders. In this study, we utilized P2X7R knockout (P2X7R−/−) mice to determine the role of the receptor in radiation-induced salivary gland damage. Results indicate a dose-dependent increase in γ-radiation-induced ATP release from primary parotid gland cells of wild-type but not P2X7R−/− mice. Despite these differences, apoptosis levels are similar in parotid glands of wild-type and P2X7R−/− mice 24–72 h after radiation. However, γ-radiation caused elevated prostaglandin E2 (PGE2) release from primary parotid cells of wild-type but not P2X7R−/− mice. To attempt to uncover the mechanism underlying differential PGE2 release, we evaluated the expression and activities of cyclooxygenase and PGE synthase isoforms. There were no consistent trends in these mediators following radiation that could explain the reduction in PGE2 release in P2X7R−/− mice. Irradiated P2X7R−/− mice have stimulated salivary flow rates similar to unirradiated controls, whereas irradiated wild-type mice have significantly decreased salivary flow rates compared with unirradiated controls. Notably, treatment with the P2X7R antagonist A438079 preserves stimulated salivary flow rates in wild-type mice following γ-radiation. These data suggest that P2X7R antagonism is a promising approach for preventing γ-radiation-induced hyposalivation.

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Phosphorylation of the Mdm2 oncoprotein by the c-Abl tyrosine kinase regulates p53 tumor suppression and the radiosensitivity of mice

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1611798114 ◽

2016 ◽

Vol 113 (52) ◽

pp. 15024-15029 ◽

Cited By ~ 5

Author(s):

Michael I. Carr ◽

Justine E. Roderick ◽

Hong Zhang ◽

Bruce A. Woda ◽

Michelle A. Kelliher ◽

...

Keyword(s):

Bone Marrow ◽

Dna Damage ◽

Tumor Suppression ◽

Bone Marrow Failure ◽

Genotoxic Stress ◽

Whole Body ◽

Atm Kinase ◽

Radiation Induced

The p53 tumor suppressor acts as a guardian of the genome by preventing the propagation of DNA damage-induced breaks and mutations to subsequent generations of cells. We have previously shown that phosphorylation of the Mdm2 oncoprotein at Ser394 by the ATM kinase is required for robust p53 stabilization and activation in cells treated with ionizing radiation, and that loss of Mdm2 Ser394 phosphorylation leads to spontaneous tumorigenesis and radioresistance in Mdm2S394A mice. Previous in vitro data indicate that the c-Abl kinase phosphorylates Mdm2 at the neighboring residue (Tyr393) in response to DNA damage to regulate p53-dependent apoptosis. In this present study, we have generated an Mdm2 mutant mouse (Mdm2Y393F) to determine whether c-Abl phosphorylation of Mdm2 regulates the p53-mediated DNA damage response or p53 tumor suppression in vivo. The Mdm2Y393F mice develop accelerated spontaneous and oncogene-induced tumors, yet display no defects in p53 stabilization and activity following acute genotoxic stress. Although apoptosis is unaltered in these mice, they recover more rapidly from radiation-induced bone marrow ablation and are more resistant to whole-body radiation-induced lethality. These data reveal an in vivo role for c-Abl phosphorylation of Mdm2 in regulation of p53 tumor suppression and bone marrow failure. However, c-Abl phosphorylation of Mdm2 Tyr393 appears to play a lesser role in governing Mdm2-p53 signaling than ATM phosphorylation of Mdm2 Ser394. Furthermore, the effects of these phosphorylation events on p53 regulation are not additive, as Mdm2Y393F/S394A mice and Mdm2S394A mice display similar phenotypes.

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Musashi expression in intestinal stem cells attenuates radiation-induced decline in intestinal permeability and survival in Drosophila

Scientific Reports ◽

10.1038/s41598-020-75867-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Amit Sharma ◽

Kazutaka Akagi ◽

Blaine Pattavina ◽

Kenneth A. Wilson ◽

Christopher Nelson ◽

...

Keyword(s):

Intestinal Permeability ◽

Rna Binding ◽

Genotoxic Stress ◽

Intestinal Stem Cells ◽

Potential Therapeutic Target ◽

Environmental Agents ◽

Radiation Induced ◽

Molecular Effects ◽

Effects Of Radiation ◽

Permeability Assay

Abstract Exposure to genotoxic stress by environmental agents or treatments, such as radiation therapy, can diminish healthspan and accelerate aging. We have developed a Drosophila melanogaster model to study the molecular effects of radiation-induced damage and repair. Utilizing a quantitative intestinal permeability assay, we performed an unbiased GWAS screen (using 156 strains from the Drosophila Genetic Reference Panel) to search for natural genetic variants that regulate radiation-induced gut permeability in adult D. melanogaster. From this screen, we identified an RNA binding protein, Musashi (msi), as one of the possible genes associated with changes in intestinal permeability upon radiation. The overexpression of msi promoted intestinal stem cell proliferation, which increased survival after irradiation and rescued radiation-induced intestinal permeability. In summary, we have established D. melanogaster as an expedient model system to study the effects of radiation-induced damage to the intestine in adults and have identified msi as a potential therapeutic target.

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Stra13 is induced by genotoxic stress and regulates ionizing‐radiation‐induced apoptosis

EMBO Reports ◽

10.1038/sj.embor.7400912 ◽

2007 ◽

Vol 8 (4) ◽

pp. 401-407 ◽

Cited By ~ 33

Author(s):

Tin Htwe Thin ◽

Li Li ◽

Teng‐Kai Chung ◽

Hong Sun ◽

Reshma Taneja

Keyword(s):

Ionizing Radiation ◽

Genotoxic Stress ◽

Radiation Induced ◽

Induced Apoptosis

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Necdin modulates proliferative cell survival of human cells in response to radiation-induced genotoxic stress

BMC Cancer ◽

10.1186/1471-2407-12-234 ◽

2012 ◽

Vol 12 (1) ◽

Cited By ~ 3

Author(s):

Julie Lafontaine ◽

Guergana Tchakarska ◽

Francis Rodier ◽

Anne-Marie Mes-Masson

Keyword(s):

Cell Survival ◽

Genotoxic Stress ◽

Human Cells ◽

Radiation Induced ◽

Proliferative Cell

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CDC42 Gtpase Activation Affects Hela Cell DNA Repair and Proliferation Following UV Radiation-Induced Genotoxic Stress

Journal of Cellular Biochemistry ◽

10.1002/jcb.25166 ◽

2015 ◽

Vol 116 (9) ◽

pp. 2086-2097 ◽

Cited By ~ 10

Author(s):

Liv G. Ascer ◽

Yuli T. Magalhaes ◽

Gisele Espinha ◽

Juliana H. Osaki ◽

Renan C. Souza ◽

...

Keyword(s):

Dna Repair ◽

Hela Cell ◽

Uv Radiation ◽

Genotoxic Stress ◽

Radiation Induced ◽

Gtpase Activation

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Restraining Akt1 Phosphorylation Attenuates the Repair of Radiation-Induced DNA Double-Strand Breaks and Reduces the Survival of Irradiated Cancer Cells

International Journal of Molecular Sciences ◽

10.3390/ijms19082233 ◽

2018 ◽

Vol 19 (8) ◽

pp. 2233 ◽

Cited By ~ 6

Author(s):

Klaudia Szymonowicz ◽

Sebastian Oeck ◽

Adam Krysztofiak ◽

Jansje van der Linden ◽

George Iliakis ◽

...

Keyword(s):

Cancer Cells ◽

Genotoxic Stress ◽

Strand Break ◽

Effector Proteins ◽

Dna Double Strand Breaks ◽

Dsb Repair ◽

Dna Double Strand Break ◽

Neutral Comet Assay ◽

Radiation Induced ◽

Clonogenic Cell

The survival kinase protein kinase B (Akt) participates in the regulation of essential subcellular processes, e.g., proliferation, growth, survival, and apoptosis, and has a documented role in promoting resistance against genotoxic stress including radiotherapy, presumably by influencing the DNA damage response and DNA double-strand break (DSB) repair. However, its exact role in DSB repair requires further elucidation. We used a genetic approach to explore the consequences of impaired phosphorylation of Akt1 at one or both of its key phosphorylation sites, Threonine 308 (T308) or Serine 473 (S473), on DSB repair and radiosensitivity to killing. Therefore, we overexpressed either the respective single or the double phosphorylation-deficient mutants (Akt1-T308A, Akt1-S473A, or Akt1-T308A/S473A) in TRAMPC1 murine prostate cancer cells (TrC1) and measured the DSB repair kinetics and clonogenic cell survival upon irradiation. Only the expression of the Akt1-T308A/S473A induced a significant delay in the kinetics of DSB repair in irradiated TrC1 as determined by the γH2A.X (H2A histone family, member X) assay and the neutral comet assay, respectively. Moreover, Akt1-T308A/S473A-expressing cells were characterized by increased radiosensitivity compared to Akt1-WT (wild type)-expressing cells in long-term colony formation assays. Our data reveal that Akt1’s activation state is important for the cellular radiation response, presumably by modulating the phosphorylation of effector proteins involved in the regulation of DSB repair.

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