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Relationship: 2856

Title

A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

Increase, DNA strand breaks leads to Altered Signaling

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes.Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name Adjacency Weight of Evidence Quantitative Understanding Point of Contact Author Status OECD Status
Deposition of energy leads to vascular remodeling adjacent High Moderate Vinita Chauhan (send email) Open for citation & comment
Deposition of Energy Leading to Learning and Memory Impairment adjacent Moderate Low Vinita Chauhan (send email) Open for citation & comment

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER.  More help
Term Scientific Term Evidence Link
human Homo sapiens Low NCBI
mouse Mus musculus Moderate NCBI
rat Rattus norvegicus Moderate NCBI

Sex Applicability

An indication of the the relevant sex for this KER. More help
Sex Evidence
Male Moderate
Female Low

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help
Term Evidence
Juvenile Low
Adult Moderate

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help

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

Include a description of the approach for identification and assembly of the evidence base for the KER. For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings.  Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

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

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help

Overall weight of evidence: Moderate

Biological Plausibility
Addresses the biological rationale for a connection between KEupstream and KEdownstream.  This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured.   More help

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). 

Uncertainties and Inconsistencies
Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help

None identified

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references.  More help

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 

Response-response Relationship
Provides sources of data that define the response-response relationships between the KEs.  More help

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
Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help

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
Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

None identified

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help

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

List of the literature that was cited for this KER description. More help

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