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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

Increase, DNA strand breaks

Downstream event

The responding Key Event (KE) in a Key Event Relationship (KER). More help

Altered Signaling

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	Cataia Ives (send email)	Open for citation & comment
Deposition of Energy Leading to Learning and Memory Impairment	adjacent	Moderate	Low	Brendan Ferreri-Hanberry (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 Map 2.0

ID	Experimental Design	Species	Upstream Observation	Downstream Observation	Citation (first author, year)	Notes

Evidence Map

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

Title	First Author	Biological Plausibility	Dose Concordance	Temporal Concordance	Incidence Concordance

Biological Plausibility

Dose Concordance Evidence

Temporal Concordance Evidence

Incidence Concordance Evidence

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

Quantitative Understanding of the Linkage

Captures information that helps to define how much change in the upstream KE, and/or for how long, is needed to elicit a detectable and defined change in the downstream KE. More help

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

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.