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Event: 1512

Key Event Title

A descriptive phrase which defines a discrete biological change that can be measured. More help

Unfolded Protein Response

Short name

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Biological Context

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Level of Biological Organization
Molecular

Cell term

The location/biological environment in which the event takes place.The biological context describes the location/biological environment in which the event takes place. For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable. For individual/population events, the organ context is not applicable. Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Organ term

Key Event Components

The KE, as defined by a set structured ontology terms consisting of a biological process, object, and action with each term originating from one of 14 biological ontologies (Ives, et al., 2017; https://aopwiki.org/info_pages/2/info_linked_pages/7#List). Biological process describes dynamics of the underlying biological system (e.g., receptor signalling).Biological process describes dynamics of the underlying biological system (e.g., receptor signaling). The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signaling by that receptor). Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description. To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons. If a desired term does not exist, a new term request may be made via Term Requests. Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add. Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE.Clicking on the name of the AOP will bring you to the individual page for that AOP. More help

AOP Name	Role of event in AOP	Point of Contact	Author Status
CYP2E1 activation and formation of protein adducts leading to neurodegeneration	KeyEvent	Jelle Broeders (send email)	Under development: Not open for comment. Do not cite
Inhibition of N-linked glycosylation leads to liver injury	KeyEvent	Marvin Martens (send email)	Under development: Not open for comment. Do not cite
Calcium overload driven development of parkinsonian motor deficits	KeyEvent	Julia Meerman (send email)	Under development: Not open for comment. Do not cite

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 KE.In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help

Life Stages

An indication of the the relevant life stage(s) for this KE. More help

Sex Applicability

An indication of the the relevant sex for this KE. More help

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. More help

The endoplasmic reticulum is responsible for the synthesis of proteins that are secreted from the cell. The folding of these proteins inside the endoplasmic reticulum is a precise mechanism, however the folding capacity is limited. Building block for the folding of the proteins are chaperones and foldases. Stress in the endoplasmic reticulum starts when the demand for protein folding increases over the protein folding capacity. Another factor is the accumulation of unfolded proteins in the endoplasmic reticulum which can cause stress. The stress leads to the activation of the UPR. Three effectors are released: ATF6, IRE1 and PERK. During the release chaperone BiP (GRP78) is removed from the effectors which maintain them in inactive state. The role of the unfolded protein response is to maintain the protein homeostasis in the endoplasmic reticulum.

Description from EU-ToxRisk:

Activation of UPR sensors (IRE1/PERK/ATF6) -> activation of transcription factors (XBP1/ATF4/ATF6f) -> activation of downstream targets (CHOP &Bip)

How It Is Measured or Detected

A description of the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements.These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA). Do not provide detailed protocols. More help

GRP78 can be used as a biomarker for endoplasmic stress and as discussed before this protein is released from the effector when the unfolded protein reaction occurs. The detection of the GRP78 protein is possible with the use of 2D gel electrophoresis in combination with proteomics. Proteins are extracted from cells, which were incubated with a toxicant, and sampled on the 2D gel. Separation is done based on the protein size and the pH value. Because of the low abundance the GRP78 protein can also be made visible with immunohistochemistry and imaging using an anti-GRP78 antibody. The protein of interest form the 2D gel can be purified and cleaned for the identification with mass spectrometry.

Description from EU-ToxRisk:

Activation of the sensors, transcription factors and targets can be measured through several assays (Takayanagi, et al 2013) and fluorescent reporter cell lines (Wink et al., 2014)

Domain of Applicability

A description of the scientific basis for the indicated domains of applicability and the WoE calls (if provided). More help

References

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

Yang, F. & Luo, J. Endoplasmic reticulum stress and ethanol neurotoxicity. Biomolecules 5, 2538–2553 (2015).

Guan, M. et al. MDA-9 and GRP78 as potential diagnostic biomarkers for early detection of melanoma metastasis. Tumour Biol. 36, 2973–82 (2015).

Foufelle, F. & Fromenty, B. Role of endoplasmic reticulum stress in drug-induced toxicity. Pharmacol. Res. Perspect. 4, e00211 (2016).

Takayanagi, S., Fukuda, R., Takeuchi, Y., Tsukada, S., & Yoshida, K. (2013). Gene regulatory network of unfolded protein response genes in endoplasmic reticulum stress. Cell Stress and Chaperones, 18(1), 11–23. https://doi.org/10.1007/s12192-012-0351-5

Wink, S., Hiemstra, S., Huppelschoten, S., Danen, E., Niemeijer, M., Hendriks, G., … Van De Water, B. (2014). Quantitative high content imaging of cellular adaptive stress response pathways in toxicity for chemical safety assessment. Chemical Research in Toxicology, 27(3), 338–355. https://doi.org/10.1021/tx4004038