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Relationship: 2856
Title
Increase, DNA strand breaks leads to Altered Signaling
Upstream event
Downstream event
Key Event Relationship Overview
AOPs Referencing Relationship
Taxonomic Applicability
Sex Applicability
Sex | Evidence |
---|---|
Male | Moderate |
Female | Low |
Life Stage Applicability
Term | Evidence |
---|---|
Juvenile | Low |
Adult | Moderate |
Key Event Relationship Description
DNA strand breaks can lead to altered signaling of various pathways through the DNA damage response. DNA strand breaks, which are a form of DNA damage, can induce ataxia telangiectasia mutated (ATM) and ATM/RAD3-related (ATR), two phosphoinositide 3-kinase (PI3K)-related serine/threonine kinases (PIKKs) (Abner and McKinnon, 2004; Lee and McKinnon, 2007; Nagane et al., 2021; Sylvester et al., 2018; Thadathil et al., 2019; Wang et al., 2020; Wang et al., 2017). Following DNA strand breaks, DNA damage response cellular signaling can phosphorylate downstream proteins and activate several transcription factors and pathways (Wang et al., 2017). Spontaneous DNA strand breaks from endogenous sources will induce signaling as a normal response to facilitate DNA repair. However, excessive DNA damage induced by a stressor will result in increased activation of these pathways and subsequent harmful downstream effects. Signaling pathways induced by DNA strand breaks include p53/p21 (Abner and McKinnon, 2004; Baselet et al., 2018; Lee and McKinnon, 2007; Nagane et al., 2021; Sylvester et al., 2018; Thadathil et al., 2019; Wang et al., 2020; Wang et al., 2017), caspase (Abner and McKinnon, 2004; Baselet et al., 2019; Wang et al., 2020; Wang et al., 2016) and mitogen-activated protein kinase (MAPK) family pathways (Ghahremani et al., 2002; Nagane et al., 2021).
Evidence Collection Strategy
The strategy for collating the evidence on radiation stressors to support the relationship is described in Kozbenko et al 2022. Briefly, a scoping review methodology was used to prioritize studies based on a population, exposure, outcome, endpoint statement.
Evidence Supporting this KER
Overall weight of evidence: Moderate
Biological Plausibility
There is strong evidence supporting the link between DNA strand breaks leading to altered signaling pathways. Single strand breaks (SSBs) or double strand breaks (DSBs) in DNA from both endogenous and exogenous sources can induce the DNA damage response, which can result in the induction of various signaling pathways (Baselet et al., 2019). DNA strand breaks are well known to lead to the activation of ATM and ATR as part of the normal DNA damage response (Abner and McKinnon, 2004; Baselet et al., 2019; Lee and McKinnon, 2007; Nagane et al., 2021; Sylvester et al., 2018; Thadathil et al., 2019; Wang et al., 2020; Wang et al., 2017; Wang et al., 2016). While ATM tends to be recruited to DSBs, ATR is recruited by many types of DNA damage including both DSBs and SSBs (Maréchal and Zou, 2013; Wang et al., 2017). Following a DNA DSB, the Mre11-Rad50-Nbs1 (MRN) complex senses and directly binds to the DNA ends at the site of the break, which subsequently activates ATM (Lee and McKinnon, 2007; Maréchal and Zou, 2013). Following a DNA SSB, resection of the damaged strand by apurinic/apyrimidinic endonuclease (APE)1/APE2 is followed by coating the single-stranded DNA with replication protein A (RPA), where the recruitment of the ATR-ATR interacting protein (ATRIP) complex and the activation of ATR occurs (Caldecott, 2022; Maréchal and Zou, 2013).
ATM and ATR can phosphorylate over 700 proteins (Nagane et al., 2021), and phosphorylation of key signaling proteins by ATM/ATR will alter signaling in their respective pathways. High levels of DNA strand breaks induced by exogenous stressors will enhance ATM/ATR activation and subsequently further activate downstream signaling, leading to downstream consequences. The extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 MAPK subfamily pathways can be phosphorylated and activated by ATM/ATR (Ghahremani et al., 2002; Nagane et al., 2021). Additionally, ATM/ATR can phosphorylate p53 on serine 15 to enhance the stability of p53, leading to activation of the p53 pathway and changes in the transcriptional activity of p53 (Abner and McKinnon, 2004; Baselet et al., 2019; Lee and McKinnon, 2007; Nagane et al., 2021; Sylvester et al., 2018; Thadathil et al., 2019; Wang et al., 2020; Wang et al., 2017; Wang et al., 2016). The apoptosis pathway downstream of p53 can also be activated by DNA strand breaks (Abner and McKinnon, 2004; Baselet et al., 2019; Lee and McKinnon, 2007; Thadathil et al., 2019; Wang et al., 2020).
Empirical Evidence
Evidence for this relationship was collected from studies using in vivo mouse and rat models as well as in vitro mouse-derived, rat-derived and human-derived cell models. The stressors used to support this relationship include 137Cs gamma rays and X rays. Markers of DNA strand breaks in this KER include p53 binding protein 1 (53BP1), phosphorylation of H2AX (γ-H2AX), phosphorylation of ATR (p-ATR) and phosphorylation of ATM (p-ATM). Altered signaling was measured mostly by the protein expression of the p53/p21 and apoptosis pathways.
Dose Concordance
A few studies have indicated a dose concordance between the increase in DNA strand breaks and altered signaling pathways. X-ray irradiation of rat cortical neurons showed increased DNA damage markers, γ-H2AX, p-ATM and p-ATR and increased levels of signaling proteins, including p21, p-p53 and cleaved caspase 3 at both doses of 8 and 32 Gy (Sabirzhanov et al., 2020). 137Cs gamma irradiated cerebromicrovascular endothelial cells (CMVECs) and rat hippocampal neurons showed increased DNA strand breaks, measured by comet assay, at 2-10 Gy, and increased caspase 3/7 activity at 2, 4 and 6 Gy (Ungvari et al., 2013).
Time Concordance
Many studies demonstrate that DNA strand breaks occur before altered signaling in a time course. Although both KEs can occur quickly, Gionchiglia et al. (2021) showed in mice that γ-H2AX and p53BP1 foci were increased as early as 15 minutes after 10 Gy of X-ray irradiation while cleaved caspase 3 did not increase until 30 minutes after irradiation. In HT22 hippocampal neurons irradiated with 12 Gy of X-rays, γ-H2AX and p-ATM were increased at 30 minutes post-irradiation while p53 was increased after 1 h and caspase 3 was increased after 48 h (Zhang et al., 2017). Similarly, rat cortical neurons irradiated with 8 Gy of X-rays showed increased p-ATM, γ-H2AX and p-ATR after 30 minutes, while p-p53, p21 and cleaved caspase 3 did not increase until 3 or 6 h post-irradiation (Sabirzhanov et al., 2020). Multiple studies using human- and rat-derived endothelial cells irradiated with 4 Gy of 137Cs gamma rays show increased DNA strand breaks at 1 h post-irradiation, with altered signaling to p53 and p21 at 6 h and to caspase 3/7 at 18 h post-irradiation (Kim et al., 2014; Park et al., 2022; Ungvari et al., 2013). In a longer-term study irradiating human lung microvascular endothelial cells (HMVEC-L) with 15 Gy of X-rays, increased DNA strand breaks were observed at 14 days post-irradiation, while altered signaling in the p53 pathway was observed at 21 days post-irradiation (Lafargue et al., 2017).
Incidence concordance
A few studies have demonstrated an incidence concordance between DNA strand breaks and altered signaling at equivalent doses. Following X-ray irradiation of mice, DNA damage markers, γ-H2AX and p53BP1, increased by 10, 15 and 5-fold in different region of the brain, while cleaved caspase 3 signaling molecule increased by 1.4 and 2.6-fold (Gionchiglia et al., 2021). Gamma ray irradiation of Wistar rats showed a 6-fold increase in DNA damage marker compared to a 0.2-fold decrease in (B-cell lymphoma 2) Bcl-2 and a 2- to 4-fold increase in signaling proteins p53, Bcl-2-associated protein X (Bax) and caspase 3/8/9 (El-Missiry et al., 2018).
Essentiality
Some studies show that preventing an increase in DNA strand breaks will restore signaling. Treatment with mesenchymal stem cell-conditioned medium (MSC-CM) reduced γ-H2AX, decreased the levels of p53, Bax, cleaved caspase 3 and increased the levels of Bcl-2 in HT22 cells irradiated with 10 Gy of X-rays (Huang et al., 2021). The inhibition of microRNA (miR)-711 decreased levels of DNA damage markers, p-ATM, p-ATR and γ-H2AX, and decreased signaling molecules including p-p53, p21 and cleaved caspase 3 (Sabirzhanov et al., 2020).
Uncertainties and Inconsistencies
None identified
Known modulating factors
Modulating factor |
Details |
Effects on the KER |
References |
Media |
MSC-CM |
Treatment decreased γ-H2AX, p53, the Bax/Bcl-2 ratio and cleaved caspase 3 in irradiated neurons. |
Huang et al., 2021 |
Genetic |
miR-711 |
miR-711 inhibition reduced the DNA damage response including p-ATM, p-ATR, and γ-H2AX. It also decreased signaling molecules including p-p53, p21, and cleaved caspase 3. |
Sabirzhanov et al., 2020 |
Drug |
Minocycline |
Treatment with minocycline in irradiated neurons reduced the DNA damage response through reduced γ-H2AX and p-ATM. Caspase 3 was also inhibited by minocycline, but p53 was not changed. |
Zhang et al., 2017 |
Drug |
Metformin |
Treatment reduced p-ATM, p-p53 and p21 levels, but did not change the level of 53BP1 in irradiated HAECs. |
Park et al., 2022 |
Quantitative Understanding of the Linkage
The tables below provide some representative examples of quantitative linkages between the two key events. All data that is represented is statistically significant unless otherwise indicated.
Response-response Relationship
Dose Concordance
Reference |
Experiment Description |
Result |
Sabirzhanov et al., 2020 |
In vitro. Rat cortical neurons were exposed to 2, 8 and 32 Gy X-rays. DNA damage was determined by γ-H2AX staining and western blot analysis of p-ATM and p-ATR. Altered signaling was determined by levels of p-p53, p21, cleaved caspase 3, measured by Western blot. |
Irradiated primary cortical neurons showed increased γ-H2AX by 30-fold at both 8 and 32 Gy but not at 2 Gy. p-ATM was increased at all doses, increasing about 15-fold at 8 and 32 Gy. Signaling molecules including p-p53, p21, and cleaved caspase 3 were increased at all doses. |
Ungvari et al., 2013 |
In vitro. CMVECs and rat hippocampal neurons were irradiated with 137Cs gamma rays. DNA strand breaks were assessed with the comet assay. Caspase 3/7 activity was determined by an assay kit. |
DNA damage increased at all doses (2-10 Gy). In the control, less than 5% of DNA was in the tail while by 6 Gy 35% of the DNA was in the tail in CMVECs and 25% was in the tail in neurons. In CMVECs, 2, 4, and 6 Gy increased caspase 3/7 activity 5- to 6-fold. |
Incidence Concordance
Reference |
Experiment Description |
Result |
El-Missiry et al., 2018 |
In vivo. Wistar rats were irradiated with 4 Gy of 137Cs gamma rays (0.695 cGy/s). DNA damage was assessed with a comet assay. Multiple signaling proteins were assessed with assay kits. |
The tail moment increased 6-fold while signaling proteins including p53, Bax, and caspases 3/8/9 increased 2- to 4-fold, and Bcl-2 decreased 0.2-fold. |
Gionchiglia et al., 2021 |
In vivo. CD1 and B6/129 mice were irradiated with 10 Gy of X-rays. γ-H2AX and 53BP1 foci were quantified with immunofluorescence. Cleaved caspase 3 positive cells were measured with immunofluorescence. |
γ-H2AX and p53BP1 foci increased about 10-fold in the forebrain and cerebral cortex, about 15-fold in the hippocampus and about 5-fold in the subventricular zone (SVZ)/ rostral migratory stream (RMS)/ olfactory bulb (OB). Cleaved caspase 3 increased 1.4-fold in the cerebral cortex and hippocampus and 2.6-fold in the SVZ/RMS/OB. |
Time-scale
Time Concordance
Reference |
Experiment Description |
Result |
Zhang et al., 2017 |
In vitro. HT22 cells were irradiated with 12 Gy of X-rays (1.16 Gy/min). p-ATM, γ-H2AX, cleaved caspase 3 and p53 were measured with Western blot. |
p-ATM and γ-H2AX were increased 4.4-fold and 3.2-fold, respectively, 30 minutes after 12 Gy. p53 was increased 4.6-fold at 1 h post-irradiation. A 9-fold increase in cleaved caspase 3 was observed 48 h post-irradiation. |
Gionchiglia et al., 2021 |
In vivo. CD1 and B6/129 mice were irradiated with 10 Gy of X-rays. γ-H2AX and 53BP1 foci were quantified with immunofluorescence in neurons. Cleaved caspase 3 positive neurons were measured with immunofluorescence. |
At both 15 and 30 minutes post-irradiation, γ-H2AX and p53BP1 foci increased. However, cleaved caspase 3 increased at 30 minutes but not at 15 minutes. |
Sabirzhanov et al., 2020 |
In vitro. Rat cortical neurons were exposed to 2, 8 and 32 Gy X-rays. DNA damage was determined by γ-H2AX staining and western blot analysis of p-ATM and p-ATR. Altered signaling was determined by levels of p-p53, p21, cleaved caspase 3, measured by Western blot. |
DNA damage occurred as early as 30 min post 8 Gy irradiation, indicated by increased p-ATM, γ-H2AX and p-ATR. Signaling molecules p-p53, p21 and cleaved caspase 3 increased at 3 or 6h post-irradiation. |
Park et al., 2022 |
In vitro. Human aortic endothelial cells (HAECs) were irradiated with 4 Gy of 137Cs gamma rays (3.5 Gy/min). γ-H2AX was measured with western blot. p-ATM and 53BP1 were determined with immunofluorescence. p-p53 and p21 were measured with Western blot. |
γ-H2AX, p-ATM, and 53BP1 were shown increased at 1 h post-irradiation, while p-p53 and p21 were increased at 6 h post-irradiation. |
Kim et al., 2014 |
In vitro. Human umbilical vein endothelial cells (HUVECs) were irradiated with 4 Gy 137Cs gamma rays. DNA damage was determined by γ-H2AX. p21 and p53 were measured by Western blot. |
γ-H2AX foci greatly increased at 1 and 6 h post-irradiation, while p-p53 and p21 were increased at 6 h post-irradiation. |
Ungvari et al., 2013 |
In vitro. CMVECs and rat hippocampal neurons were irradiated with 2-6 Gy of 137Cs gamma rays. DNA strand breaks were assessed with the comment assay. Caspase 3/7 activity was determined by an assay kit. |
DNA damage in neurons and CMVECs increased at 1 h post-irradiation, while caspase 3/7 activity increased the greatest at 18 h post-irradiation in CMVECs. |
Lafargue et al., 2017 |
In vitro. HMVEC-L were irradiated with 15 Gy of X-rays. γ-H2AX foci were assessed with immunofluorescence. p-ATM and ATM were assessed with Western blot. Signaling proteins including p53, p21 and p16 were assessed with western blot. |
Without irradiation, most cells had 0 or 1 γ-H2AX foci, while 14 days after 15 Gy, most cells had 2-6 γ-H2AX foci. The ratio of p-ATM/ATM was also increased 14 days after 15 Gy. p53, p21, and p16 were all increased at 21 days after 15 Gy. |
Known Feedforward/Feedback loops influencing this KER
None identified
Domain of Applicability
Evidence for this relationship is predominantly from studies using rat- and mouse-derived cells, with some in vivo evidence in mice and rats. There is in vivo evidence in male animals, but no in vivo studies specify the use of female animals. In vivo evidence is from adult models.
References
Abner, C. W. and P. J. McKinnon. (2004), "The DNA double-strand break response in the nervous system", DNA Repair, Vol. 3/8–9, Elsevier, Amsterdam, https://doi.org/10.1016/j.dnarep.2004.03.009.
Baselet, B. et al. (2019), "Pathological effects of ionizing radiation: endothelial activation and dysfunction", Cellular and Molecular Life Sciences, Vol. 76/4, Springer Nature, https://doi.org/10.1007/s00018-018-2956-z.
Caldecott, K. W. (2022), “DNA single-strand break repair and human genetic disease”, Trends in Cell Biology, 32(9), Elsevier, Amsterdam, https://doi.org/10.1016/j.tcb.2022.04.010
El-Missiry, M. A. et al. (2018), "Neuroprotective effect of epigallocatechin-3-gallate (EGCG) on radiation-induced damage and apoptosis in the rat hippocampus", International Journal of Radiation Biology, Vol. 94/9, Informa, London, https://doi.org/10.1080/09553002.2018.1492755.
Ghahremani, H. et al. (2002), “Interaction of the c-Jun/JNK Pathway and Cyclin-dependent Kinases in Death of Embryonic Cortical Neurons Evoked by DNA Damage”, Journal of Biological Chemistry, Vol. 277/38, Elsevier, Amsterdam, https://doi.org/10.1074/jbc.M204362200
Gionchiglia, N. et al. (2021), "Association of Caspase 3 Activation and H2AX γ Phosphorylation in the Aging Brain: Studies on Untreated and Irradiated Mice", Biomedicines, Vol. 9/9, MDPI, Basel, https://doi.org/10.3390/biomedicines9091166.
Huang, Y. et al. (2021), "Mesenchymal Stem Cell-Conditioned Medium Protects Hippocampal Neurons From Radiation Damage by Suppressing Oxidative Stress and Apoptosis", Dose-Response, Vol. 19/1, SAGE publications, https://doi.org/10.1177/1559325820984944.
Kozbenko, T. et al. (2022), “Deploying elements of scoping review methods for adverse outcome pathway development: a space travel case example”, International Journal of Radiation Biology, Vol. 98/12. https://doi.org/10.1080/09553002.2022.2110306
Kim, K. S. et al. (2014), "Characterization of DNA damage-induced cellular senescence by ionizing radiation in endothelial cells", International Journal of Radiation Biology, Vol. 90/1, Informa, London, https://doi.org/10.3109/09553002.2014.859763.
Lafargue, A. et al. (2017), "Ionizing radiation induces long-term senescence in endothelial cells through mitochondrial respiratory complex II dysfunction and superoxide generation", Free Radical Biology and Medicine, Vol. 108, Elsevier, Amsterdam, https://doi.org/10.1016/j.freeradbiomed.2017.04.019.
Lee, Y. and P. J. McKinnon. (2007), "Responding to DNA double strand breaks in the nervous system", Neuroscience, Vol. 145/4, Elsevier, Amsterdam, https://doi.org/10.1016/j.neuroscience.2006.07.026.
Maréchal, A. and L. Zou. “DNA damage sensing by the ATM and ATR kinases”, Cold Spring Harbor Perspectives in Biology, 5(9), Cold Spring Harbor Laboratory Press, https://doi.org/10.1101/cshperspect.a012716
Nagane, M. et al. (2021), "DNA damage response in vascular endothelial senescence: Implication for radiation-induced cardiovascular diseases", Journal of Radiation Research, Vol. 62/4, Oxford University Press, Oxford, https://doi.org/10.1093/jrr/rrab032.
Park, J.-W. et al. (2022), "Metformin alleviates ionizing radiation-induced senescence by restoring BARD1-mediated DNA repair in human aortic endothelial cells", Experimental Gerontology, Vol. 160, Elsevier, Amsterdam, https://doi.org/10.1016/j.exger.2022.111706.
Sabirzhanov, B. et al. (2020), "Irradiation-Induced Upregulation of miR-711 Inhibits DNA Repair and Promotes Neurodegeneration Pathways", International Journal of Molecular Sciences, Vol. 21/15, MDPI, Basel, https://doi.org/10.3390/ijms21155239.
Sylvester, C. B. et al. (2018), "Radiation-Induced Cardiovascular Disease: Mechanisms and Importance of Linear Energy Transfer", Frontiers in Cardiovascular Medicine, Vol. 5, Fronteirs, https://doi.org/10.3389/fcvm.2018.00005.
Thadathil, N. et al. (2019), "DNA double-strand breaks: a potential therapeutic target for neurodegenerative diseases", Chromosome Research, Vol. 27/4, Springer Nature, https://doi.org/10.1007/s10577-019-09617-x.
Ungvari, Z. et al. (2013), "Ionizing Radiation Promotes the Acquisition of a Senescence-Associated Secretory Phenotype and Impairs Angiogenic Capacity in Cerebromicrovascular Endothelial Cells: Role of Increased DNA Damage and Decreased DNA Repair Capacity in Microvascular Radiosensitivity", The journals of gerontology. Series A, Biological sciences and medical sciences, Vol. 68/12, Oxford University Press, Oxford, https://doi.org/10.1093/gerona/glt057.
Wang, Q. et al. (2020), "Radioprotective Effect of Flavonoids on Ionizing Radiation-Induced Brain Damage", Molecules, Vol. 25/23, MDPI, Basel, https://doi.org/10.3390/molecules25235719.
Wang, H. et al. (2017), "Chronic oxidative damage together with genome repair deficiency in the neurons is a double whammy for neurodegeneration: Is damage response signaling a potential therapeutic target?", Mechanisms of Ageing and Development, Vol. 161, Elsevier, Amsterdam, https://doi.org/10.1016/j.mad.2016.09.005.
Wang, Y., M. Boerma and D. Zhou. (2016), "Ionizing Radiation-Induced Endothelial Cell Senescence and Cardiovascular Diseases", Radiation Research, Vol. 186/2, BioOne, https://doi.org/10.1667/RR14445.1.
Zhang, L. et al. (2017), "The inhibitory effect of minocycline on radiation-induced neuronal apoptosis via AMPKα1 signaling-mediated autophagy", Scientific Reports, Vol. 7/1, Springer Nature, https://doi.org/10.1038/s41598-017-16693-8.