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Relationship: 2683


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

dimerization, AHR/ARNT leads to Increase, slincR expression

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
Aryl hydrocarbon receptor activation leading to early life stage mortality via sox9 repression induced impeded craniofacial development adjacent Moderate Moderate Prarthana Shankar (send email) Under development: Not open for comment. Do not cite Under Review
Aryl hydrocarbon receptor activation leading to early life stage mortality via sox9 repression induced cardiovascular toxicity adjacent Moderate Moderate Prarthana Shankar (send email) Under development: Not open for comment. Do not cite Under Review

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
zebrafish Danio rerio High NCBI
mouse Mus musculus High NCBI
human Homo sapiens Moderate NCBI

Sex Applicability

An indication of the the relevant sex for this KER. More help
Sex Evidence
Unspecific High

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help
Term Evidence
Embryo High
Development High

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
  • Dimerization of Ahr/ARNT take place when the ligand-activated Ahr translocates to the nucleus from the cytoplasm. 

  • The Ahr/ARNT heterodimer can recognize aryl hydrocarbon response elements (AHREs), also known as xenobiotic response elements (XREs) or dioxin response elements (DREs), in the promoter region of downstream genes to regulate gene expression (Schmidt and Bradfield 1996). The target genes can either increase or decrease in their expression.

  • slincR expression significantly increases when zebrafish are exposed to TCDD, and the slincR promoter includes the core AHRE (5’-T/GCGTG-3’) in multiple locations (Garcia et al., 2017), suggesting that slincR is a direct downstream target of the Ahr/ARNT heterodimer.

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

Evidence gathered for this KER is primarily from two main studies, (Garcia et al., 2017) and (Garcia et al., 2018), that discovered and described slincR in zebrafish.  

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help
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
  • Eight putative AHREs have been identified in the slincR promoter of the zebrafish gene (Garcia et al., 2017).

  • The potential orthologs of slincR in the mouse and human genomes also have conserved AHREs (Garcia et al., 2018).

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
  • Certain PAHs, such as fluoranthene, phenanthrene, and 9-methylanthracene that significantly induce cyp1a greater than log2FC = 2, indicating that Ahr has been activated, do not induce slincR expression in zebrafish (Garcia et al., 2018).

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

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
  • Ahr activation (and thus, the dimerization of Ahr/ARNT) resulting in significant slincR induction of expression has only been investigated in zebrafish and mice (Garcia et al., 2017; Garcia et al., 2018).


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

Garcia GR, Goodale BC, Wiley MW, La Du JK, Hendrix DA, Tanguay RL. 2017. In vivo characterization of an ahr-dependent long noncoding rna required for proper sox9b expression. Mol Pharmacol. 91(6):609-619.

Garcia GR, Shankar P, Dunham CL, Garcia A, La Du JK, Truong L, Tilton SC, Tanguay RL. 2018. Signaling events downstream of ahr activation that contribute to toxic responses: The functional role of an ahr-dependent long noncoding rna (slincr) using the zebrafish model. Environ Health Perspect. 126(11):117002.

Prasch AL, Tanguay RL, Mehta V, Heideman W, Peterson RE. 2006. Identification of zebrafish arnt1 homologs: 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity in the developing zebrafish requires arnt1. Mol Pharmacol. 69(3):776-787.

Schmidt JV, Bradfield CA. 1996. Ah receptor signaling pathways. Annu Rev Cell Dev Biol. 12:55-89.

Shankar P, McClure RS, Waters KM, Tanguay RL. 2021. Gene co-expression network analysis in zebrafish reveals chemical class specific modules. BMC Genomics. 22(1):658.