API

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Relationship: 1765

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

Binding, SH/SeH proteins involved in protection against oxidative stress leads to Protection against oxidative stress, decreased

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Binding, SH/SeH proteins involved in protection against oxidative stress
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help
Protection against oxidative stress, decreased

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
Binding of electrophilic chemicals to SH(thiol)-group of proteins and /or to seleno-proteins involved in protection against oxidative stress during brain development leads to impairment of learning and memory adjacent Moderate Moderate Brendan Ferreri-Hanberry (send email) Open for citation & comment WPHA/WNT Endorsed

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
rat Rattus norvegicus NCBI
mouse Mus musculus NCBI
human Homo sapiens NCBI

Sex Applicability

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

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help
Term Evidence
All life stages 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

Thiol (SH) and selenol (SeH) compounds exhibit reactivity toward electrophiles and oxidants and have high binding affinities for metals (Higdon, 2012; Nagy, 2013; Winterbourn, 2008; Winther, 2014). Glutathione is a thiol-containing tripeptide acting as a cofactor for the enzyme peroxidase and thus serving as an indirect antioxidant donating the electrons necessary for its decomposition of H2O2, and is also involved in many other cellular functions (Kohen, 2002). Selenoproteins contain selenocysteine amino acid residues. The selenoprotein family is composed of proteins exerting diverse functions, among them several are oxidoreductases classified as antioxidant enzymes (Labunskyy, 2014; Reeves, 2009). Relevant for this KER there are two well-studied selenoprotein families which are described to be expressed in the brain; (i) the Glutathione Peroxidase (GPx) family, involved in detoxification of hydroperoxides; (ii) the Thioredoxin Reductase (TrxR) family, involved in the regeneration of reduced thioredoxin (Pillai, 2014), but also the less studied SelH, K, S, R, W, and P selenoproteins (Pisoschi, 2015; Reeves, 2009).

As summarized in the table 1, binding to the thiol/selenol groups of the selenoproteins cited above can result in structural modifications of these proteins, which in turn inhibits their catalytic activity and thereby reduces or blocks their metabolic capacity to neutralize reactive oxygen species (Fernandes, 1996; Rajanna, 1995). Similarly, binding to the thiol group of glutathione will decrease its anti-oxidant capacity.

Figure (Poole, 2015) Structures of cysteinyl and selenocysteinyl residues within proteins. The aminoacyl groups are shown to the left, with dotted lines representing peptide bonds to the next residue on either side. Both protonated (left) and deprotonated (right) forms of these amino acids are depicted with average pKa values.

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 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

Another important group of thiol-containing proteins are the metal-binging detoxifying metallothioneins. This protein family bind mercury and lead, and this binding thus serves as a protective mechanism and also protects against metal toxicity and oxidative stress (Aschner, 2006).

Lactational exposure to methylmercury (10 mg/L in drinking water) significantly increased cerebellar GSH level and GR activity. Possibly a compensatory response to mercury-induced oxidative stress (Franco, 2006).

MeHg was shown to inhibit cerebral thioredoxin reductase activity in vitro but not in brain of mice (Wagner et al., 2010). However, it has to be noted that the exposure of mice to MeHg was only 24h.

Inhibition og GR and GrX by Hg2+ and MeHg was observed on the puried protein, but not in HeLa cells incubated with the same concentrations for 24h (Carvahlo et al., 2008).

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

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

Experimental evidences has been observed in rat, mice and human cells (Agrawal, 2015; Meinerz, 2011; Branco, 2017)