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Relationship: 2020

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 to estrogen receptor (ER)-α leads to Induction of GATA3 expression

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Binding to estrogen receptor (ER)-α
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help
Induction of GATA3 expression

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 to estrogen receptor (ER)-α in immune cells leading to exacerbation of systemic lupus erythematosus (SLE) adjacent Moderate Moderate Yasuharu Otsubo (send email) Under development: Not open for comment. Do not cite Under Development

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

Sex Applicability

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

Life Stage Applicability

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

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

The hormone binding domain (HBD) of the ERα is required not only for binding ligand but also to form stable homodimers of the protein and mediate transcriptional activation by the receptor.  There are two ligand-dependent signaling pathway.  One is “classical” and the other is “tethered” pathway.  A direct genomic interaction occurs between the ER ligand complex and specific sequences of DNA known as estrogen response elements (ERE) (Parker MG. 1993, Goldstein RA. 1993, Sasson S. 1991, Brandt ME. 1997).  Transcriptional activation by ERα is mediated by two distinct activation functions: the constitutively active AF-1 domain, located in the N-terminal domain of the receptor protein, and the ligand-dependent AF-2 domain, located in the C-terminal domain of the receptor protein (Delaunay F. 2000).  This is called “classical” signaling pathway.  In addition to above classical mechanism, ligand-activated ERα interact with other transcription factor complexes and bind to non-EREs by attaching to other transcription factors and not with ERE directly. (Carolyn MK. 2001).  This is also called “tethered” signaling pathway.  The transcription factors GATA3 and STAT6 are essential for the establishment and/or maintenance of these interactions (Spilianakis and Flavell, 2004).  In the tethered pathway, STAT6-ER fusion protein induce GATA-3 mRNA expression.  Furthermore, in mammary gland but not in immune cells, GATA3 and ERα regulate each other and, along with FOXA1, can nucleate a remodeling complex at heterochromatic enhancer regions of ERα target genes, leading to the opening and epigenetic marking of sites for active transcription (Eeckhoute J. 2007, Kong SL. 2011).  Alone, FOXA1 or ERα are not sufficient to fully open the chromatin, supporting a bona fide pioneer activity for GATA3 (Eeckhoute J. 2007, Kong SL. 2011).

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 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

STAT6-ER fusion protein (STAT6:ER) induce expression of GATA-3 mRNAs in presence of 4-Hydroxytamoxifen (4-HT), estrogen analogue (Kurata H. 1999, Zhu J. 2001).  Furthermore, A constitutively active form of Stat6 (STAT6VT) introduced GATA3 expression and resulted in both Th2 differentiation and enhanced cell expansion without IL-4 (Zhu J. 2001, Horiuchi S. 2011).  CD4 T cells from Stat6-knockout mice are not able to drive Th2 differentiation and cell expansion under ThN conditions with added IL-4 (Zhu J. 2001).  Therefore, it is considered that activated STAT6 after ligand-biniding to ERα induce GATA3 expression in immune cells.

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

The “tethered” pathway is confirmed indirectly using artificial STAT6-ER fusion protein but not endogenous STAT6.  It remains unknown whether the “classical” pathway is utilized after binding to ERα in immune cells.

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

The Th1/Th2 shift is one of the most important immunologic changes during the menstrual cycle and gestation.  Immune activity shifts across the menstrual cycle, with higher follicular-phase Th1 cell activity and higher luteal-phase Th2 cell activity (Tierney KL. 2015).  This is due to the progressive increase of estrogens, which reach peak level in the third trimester of pregnancy. At these high levels, estrogens suppress the Th1-mediated responses and stimulate Th2-mediated immunologic responses (Doria A. 2006).  The effects of ERα signaling on T cells appear to be estrogen-dose dependent, i.e., low doses of estrogen stimulate a Th1 response, but higher doses promote a Th2 response (Priyanka HP. 2013).

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

MIE:

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KE XX:

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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

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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

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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

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References

List of the literature that was cited for this KER description. More help
  1. Parker MG, Arbuckle N, Dauvois S, Danielian P, White R. Structure and function of the estrogen receptor. Ann N Y Acad Sci. 1993. 684:119-26.
  2. Goldstein RA, Katzenellenbogen JA, Wolynes PG, et al. Three-dimensional model for the hormone binding domains of steroid receptors. Proc Natl Acad Sci. 1993;90 (21):9949-53.
  3. Sasson S. Equilibrium binding analysis of estrogen agonists and antagonists: relation to the activation of the estrogen receptor. Pathol Biol (Paris). 1991;39(1):59-69.
  4. Brandt ME, Vickery LE. Cooperativity and dimerization of recombinant human estrogen receptor hormone-binding domain. J Biol Chem. 1997;272(8):4843-9.
  5. Delaunay, F., Pettersson, K., Tujague, M., and Gustafsson, J. A. (2000). Functional Differences between the Amino-Terminal Domains of Estrogen Receptors α and β. Molecular Pharmacology 58: 584-590.
  6. Carolyn MK. Estrogen receptor interaction with estrogen response elements. Nucleic Acids Res. 2001 Jul 15; 29(14): 2905-2919.
  7. Spilianakis CG & Flavell RA, Long-range intrachromosomal interactions in the T helper type 2 cytokine locus. Nature Immunology. 2004; 5: 1017-1027.
  8. Eeckhoute J, Positive Cross-Regulatory Loop Ties GATA-3 to Estrogen Receptor α Expression in Breast Cancer. Cancer Res. 2007; 67(13):6477-83.
  9. Kong SL, Cellular reprogramming by the conjoint action of ERα, FOXA1, and GATA3 to a ligand‐inducible growth state. Mol Syst Biol (2011)7:526
  10. Kurata, H., Lee, H. J., O’Garra, A. and Arai, N. (1999). Ectopic expression of activated STAT6 induces the expression of Th2-specific cytokines and transcription factors in developing Th1 cells. Immunity 11: 677-688.
  11. Zhu, J., Guo, L., Watson, C. J., Hu-Li, J. and Paul, W. E. (2001). STAT6 is necessary and sufficient for IL-4's role in Th2 differentiation and cell expansion. The Journal of Immunology 166(12): 7276-7281.
  12. Horiuchi S, Genome-wide analysis reveals unique regulation of transcription of Th2-specific genes by GATA3. (2011) J Immunol. 1;186(11):6378-89.
  13. Lambert KC, Curran EM, et al. Estrogen receptor alpha (ERalpha) deficiency in macrophages results in increased stimulation of CD4+ T cells while 17beta-estradiol acts through ERalpha to increase IL-4 and GATA-3 expression in CD4+ T cells independent of antigen presentation. J Immunol. 2005; 175(9): 5716-23.
  14. Kamogawa, Y., Lee, H.J., Johnston, J.A., McMahon, M., O’Garra, A., and Arai, N. (1998). Cutting Edge: A conditionally active form of STAT6 can mimic certain effects of IL-4. J. Immunol. 161, 1074-1077.
  15. Tierney, K. L., Julia, R. H. and Gregory, E. D. (2015). Sexual activity modulates shifts in Th1/Th2 cytokine profile across the menstrual cycle: An observational study. Fertility and Sterility 104 (6): 1513-1521.
  16. Doria, A., Iaccarino, L., Sarzi-Puttini, P., Ghirardello, A., Zampieri, S., Arienti, S., Cutolo, M. and Todesco, S. (2006). Estrogens in pregnancy and systemic lupus erythematosus. Annals of the New York Academy of Sciences 1069: 247-256.
  17. Priyanka HP, Krishnan HC, Singh RV, Hima L, Thyagarajan S. Estrogen modulates in vitro T cell responses in a concentration- and receptor-dependent manner: effects on intracellular molecular targets and antioxidant enzymes. Mol Immunol. 2013;56(4):328-39.