Review of repair kinetics for DNA damage induced in eukaryotic cells in vitro by ionizing radiation

The aim of this study was to examine whether intermediate frequency (IF) magnetic field (MF) induces genotoxic effects or play a role in the induction of adaptive response after combined exposure to IF MF and ionizing radiation in leukocytes and in adrenocortical carcinoma cell line H295R. Cells were exposed to 250.8 kHz at the magnetic field strength of 80 A/m (equivalent to 100 µT magnetic flux density) for 20 hours alone, or exposed to IF MF for 20 hours and 24 hours later challenged with ionizing radiation (1.5 Gy X-ray). Evaluation of the DNA damage was performed with alkaline comet assay. Our results showed that there was no significant genotoxic effect of IF MF exposure compared to the controls in both cell types. Furthermore, results did not indicate a statistically significant change in DNA strand breaks in IF MF pre-exposed cells when they were subsequently exposed to 1.5 Gy. Consequently no adaptive response was detected.

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Vibrational spectroscopy in sensing radiobiological effects: analyses of targeted and non-targeted effects in human keratinocytes

Faraday Discussions ◽

10.1039/c5fd00208g ◽

2016 ◽

Vol 187 ◽

pp. 213-234 ◽

Cited By ~ 27

Author(s):

Aidan D. Meade ◽

Orla Howe ◽

Valérie Unterreiner ◽

Ganesh D. Sockalingum ◽

Hugh J. Byrne ◽

...

Keyword(s):

Dna Damage ◽

Ionizing Radiation ◽

Vibrational Spectroscopy ◽

Human Keratinocytes ◽

Mitogen Activated Protein Kinase ◽

Low Doses ◽

Damage Initiation ◽

Damage Sensing ◽

Radiobiological Effects

Modern models of radiobiological effects include mechanisms of damage initiation, sensing and repair, for those cells that directly absorb ionizing radiation as well as those that experience molecular signals from directly irradiated cells. In the former case, the effects are termed targeted effects while, in the latter, non-targeted effects. It has emerged that phenomena occur at low doses below 1 Gy in directly irradiated cells that are associated with cell-cycle-dependent mechanisms of DNA damage sensing and repair. Likewise in non-targeted bystander-irradiated cells the effect saturates at 0.5 Gy. Both effects at these doses challenge the limits of detection of vibrational spectroscopy. In this paper, a study of the sensing of both targeted and non-targeted effects in HaCaT human keratinocytes irradiated with gamma ray photons is conducted with vibrational spectroscopy. In the case of directly irradiated cells, it is shown that the HaCaT cell line does exhibit both hyperradiosensitivity and increased radioresistance at low doses, a transition between the two effects occurring at a dose of 200 mGy, and that cell survival and other physiological effects as a function of dose follow the induced repair model. Both Raman and FTIR signatures are shown to follow a similar model, suggesting that the spectra include signatures of DNA damage sensing and repair. In bystander-irradiated cells, pro- and anti-apoptotic signalling and mechanisms of ROS damage were inhibited in the mitogen-activated protein kinase (MAPK) transduction pathway. It is shown that Raman spectral profiles of bystander-irradiated cells are correlated with markers of bystander signalling and molecular transduction. This work demonstrates for the first time that both targeted and non-targeted effects of ionizing radiation damage are detected by vibrational spectroscopy in vitro.

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Immunochemical detection of DNA damage induction and repair at different cellular stages of spermatogenesis of the hamster after in vitro or in vivo exposure to ionizing radiation

Experimental Cell Research ◽

10.1016/0014-4827(91)90101-y ◽

1991 ◽

Vol 193 (2) ◽

pp. 303-309 ◽

Cited By ~ 43

Author(s):

A.A.W.M. Van Loon ◽

P.J. Den Boer ◽

G.P. Van Der Schans ◽

P. Mackenbach ◽

J.A. Grootegoed ◽

...

Keyword(s):

Dna Damage ◽

Ionizing Radiation ◽

Immunochemical Detection

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The principal phenolic and alcoholic components of wine protect human lymphocytes against hydrogen peroxide- and ionizing radiation-induced DNA damage in vitro

Mutagenesis ◽

10.1093/mutage/18.2.119 ◽

2003 ◽

Vol 18 (2) ◽

pp. 119-126 ◽

Cited By ~ 28

Author(s):

W. Greenrod ◽

M. Fenech

Keyword(s):

Hydrogen Peroxide ◽

Dna Damage ◽

Ionizing Radiation ◽

Human Lymphocytes ◽

Radiation Induced

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Can a nick promote partial genome re-replication?

10.1101/2020.11.14.381277 ◽

2020 ◽

Author(s):

Erik Johansson ◽

John F.X Diffley

Keyword(s):

Dna Damage ◽

Replication Fork ◽

Eukaryotic Cells ◽

Replication Origins ◽

Dna Breaks ◽

Replication Restart ◽

Dna Break ◽

Partial Genome ◽

Multiple Replication

AbstractSingle-stranded DNA breaks, including simple nicks, are amongst the most common forms of DNA damage in cells. They can be readily repaired by ligation; however, if a nick occurs just ahead of an approaching replisome, the outcome is a ‘collapsed’ replication fork in which the nick is converted into a single-ended double-strand DNA break. Attention has largely focused on the processes by which this broken end is used to prime replication restart. We realized that in eukaryotic cells, where replication initiates from multiple replication origins, a second fork converging on the collapsed fork offers additional opportunities for repair, but also generates a substrate that can promote localized re-replication. We have modelled this with purified proteins in vitro and have found that there is, indeed, an additional hazard that eukaryotic replisomes face. We discuss how this problem might be mitigated.

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Ionizing radiation induces ataxia telangiectasia mutated kinase (ATM)-mediated phosphorylation of LKB1/STK11 at Thr-366

Biochemical Journal ◽

10.1042/bj20021284 ◽

2002 ◽

Vol 368 (2) ◽

pp. 507-516 ◽

Cited By ~ 75

Author(s):

Gopal P. SAPKOTA ◽

Maria DEAK ◽

Agnieszka KIELOCH ◽

Nick MORRICE ◽

Aaron A. GOODARZI ◽

...

Keyword(s):

Dna Damage ◽

Protein Kinase ◽

Ionizing Radiation ◽

Ataxia Telangiectasia ◽

Cellular Responses ◽

Ataxia Telangiectasia Mutated ◽

Cancer Syndrome ◽

Phosphoinositide 3 Kinase

The serine/threonine protein kinase LKB1 functions as a tumour suppressor, and mutations in this enzyme lead to the inherited Peutz—Jeghers cancer syndrome. We previously found that LKB1 was phosphorylated at Thr-366 in vivo, a residue conserved in mammalian, Xenopus and Drosophila LKB1, located on a C-terminal non-catalytic moiety of the enzyme. Mutation of Thr-366 to Ala or Asp partially inhibited the ability of LKB1 to suppress growth of G361 melanoma cells, but did not affect LKB1 activity in vitro or LKB1 localization in vivo. As a first step in exploring the role of this phosphorylation further, we have generated a phosphospecific antibody specifically recognizing LKB1 phosphorylated at Thr-366 and demonstrate that exposure of cells to ionizing radiation (IR) induced a marked phosphorylation of LKB1 at Thr-366 in the nucleus. Thr-366 lies in an optimal phosphorylation motif for the phosphoinositide 3-kinase-like kinases DNA-dependent protein kinase (DNA-PK), ataxia telangiectasia mutated kinase (ATM) and ataxia telangiectasia-related kinase (ATR), which function as sensors for DNA damage in cells and mediate cellular responses to DNA damage. We demonstrate that both DNA-PK and ATM efficiently phosphorylate LKB1 at Thr-366 in vitro and provide evidence that ATM mediates this phosphorylation in vivo. This is based on the finding that LKB1 is not phosphorylated in a cell line lacking ATM in response to IR, and that agents which induce cellular responses via ATR in preference to ATM poorly induce phosphorylation of LKB1 at Thr-366. These observations provide the first link between ATM and LKB1 and suggest that ATM could regulate LKB1.

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Abstract MP233: Investigating Genotoxic-induced Innate Immune Pathways Leading To Heart Failure With Preserved Ejection Fraction For Developing Effective Treatments

Circulation Research ◽

10.1161/res.129.suppl_1.mp233 ◽

2021 ◽

Vol 129 (Suppl_1) ◽

Author(s):

Mohammad H Al-Khalaf ◽

David Smyth ◽

Gauri Akolkar ◽

Justin Williams ◽

Liyong Zhang ◽

...

Keyword(s):

Heart Failure ◽

Dna Damage ◽

Ionizing Radiation ◽

Ejection Fraction ◽

Cardiac Tissue ◽

Innate Immune ◽

Preserved Ejection Fraction ◽

Dna Breaks

Background: A hallmark of heart failure pathologies is excessive and cumulative DNA damage, leading to an increased and accelerated cardiac cellular senescence. We aimed to investigate the role of DNA breaks in inducing inflammation leading to adverse remodeling, premature senescence, and cardiac dysfunction leading to onset of Heart Failure with preserved Ejection Fraction (HFpEF), a specific type of disease prevalent in the aging population. Results: We use heart-focused ionizing radiation, a novel in vivo technique to induce aging related DNA damage and onset of diastolic dysfunction and HFpEF (n= 4-5 per group & per species; animals used: Rattus norvegicus and Mus musculus). We performed functional analysis, histological tissue assessment and molecular investigations to evaluate and validate this novel animal model technique. DNA damage response is upregulated in aging-related Heart Failure, and here demonstrated in our novel heart-focused radiation technique. Using in vitro ionizing radiation exposure alters cardiomyocyte morphology and activates inflammation, leading to upregulation of fibrosis and senescence markers. Finally using experimental inhibitor compounds targeting the cGAS-STING axis of innate immunity, we show effective attenuation of this relevant pathway, leading to decreased systemic inflammation, cardiomyocyte remodeling, and senescence associated with DNA damage injury. Conclusions: We present a novel technique to induce genotoxic outcomes and inflammation of the heart, leading to HFpEF pathology. We elucidate novel connections from the onset and accumulation of unresolved DNA damage, to activation of specialized innate immune cellular responses, and ultimately upregulation of cardiac tissue specific inflammation, fibrosis and senescence. Finally we demonstrate that antagonizing the cGAS-STING pathway could allow a precision medicine approach to treating genotoxic and inflammatory HFpEF.

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