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Relationship: 964


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

Activation, EGFR leads to Activation, Sp1

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

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 High NCBI
mouse Mus musculus Moderate NCBI
rat Rattus norvegicus Moderate NCBI
dog Canis lupus familiaris Moderate NCBI

Sex Applicability

An indication of the the relevant sex for this KER. More help
Sex Evidence
Mixed Low

Life Stage Applicability

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

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 EGF receptor family comprises 4 members, EGFR (also referred to as ErbB1/HER1), ErbB2/Neu/HER2, ErbB3/HER3 and ErbB4/HER4, all of which are transmembrane glycoproteins with an extracellular ligand binding site and an intracellular tyrosine kinase domain. Receptor-ligand binding induces dimerization and internalization, subsequently leading to activation of the receptor through autophosphorylation (Higashiyama et al., 2008). Classical EGFR downstream signaling involves activation of Ras which subsequently initiates signal transduction through the Raf-1/MEK/ERK pathway. MAP kinase activation in turn promotes airway epithelial cell proliferation and differentiation (Lemjabbar et al., 2003; Kim et al., 2005; Hackel et al, 1999) and facilitates epithelial wound repair (Burgel, 2004; van Winkle et al., 1997; Allahverdian et al., 2010). EGFR signal transduction via the MAPK cascade also activates the transcription factor Sp1 (Di et al., 2012; Hewson et al., 2004; Lee et al., 2011; Perrais et al., 2002; Barbier et al., 2012; Oyanagi et al, 2016).

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

Increased Sp1 activity following EGFR activation is well-documented. EGFR ligands EGF and TGFa or TGFa in combination with polyI:C increase Sp1 activity in NCI-H292 cells, a human pulmonary mucoepidermoid carcinoma cell line, by directly activating EGFR (Perrais et al., 2002; Oyanagi et al., 2016; Song et al., 2017). Sp1 activation through EGFR/MAPK activation was also reported in human airway epithelial cells following stimulation with PMA (Hewson et al. 2004) and in a mouse influenza model (Barbier et al., 2012). In addition, treatment of A549 cells with cigarette smoke extract increased Sp1 expression and nuclear translocation, resulting in enhanced Sp1-DNA binding and promoter transactivation, which could be suppressed by pretreatment with the EGFR inhibitor AG1478 (Di et al., 2012).

Other studies demonstrate EGFR-mediated activation of Sp1 in rat GH4 pituitary tumor cells (Merchant et al., 1995), Madin-Darby canine kidney (MDCK) cells (Ikari et al., 2009), human HepG2 hepatocellular carcinoma cells (Zheng et al., 2001), and human esophageal carcinoma cell lines (Lu et al., 2010).

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

Signal transduction via the MAPK cascade subsequent to EGFR activation results in Sp1 activation, and this is well-documented (Di et al., 2012; Hewson et al., 2004; Lee et al., 2011; Perrais et al., 2002; Barbier et al., 2012; Oyanagi et al, 2016). 

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 described mechanism for this KER may specifically apply in the context of increased MUC5AC gene and protein expression, but not to that of MUC5B, another gel-forming mucin associated with mucus hypersecretion in the airways (Wu et al, 2007).

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

Treatment with 20 ng/mL EGF or TGFa for 24 h induced phosphorylation of Sp1, corresponding to a 2-3-fold increase in MUC2 and MUC5AC promoter activity, which was inhibited by 100 nM mithramycin A (a Sp1 inhibitor) (Perrais et al., 2002).

H292 cells infected with IAV at MOI=1 exhibited Sp1 activation as evidenced by a 1.5- to 5-fold increase in band shift and an approx. 3-fold increase in EGFR phosphorylation at 24 h post-infection (Barbier et al., 2012).

In human primary bronchial epithelial cells treated with 10 nM TCDD, Sp1 phosphorylation and MUC5AC promoter activity increased by ca. 2-fold and 4-fold, respectively, and increased promoter activity was abrogated in the presence of the EGFR inhibitor AG1478 (Lee et al., 2011).

In human A549 lung cancer cells treated with 3% cigarette smoke extract for 3 h, Sp1 expression increased approx. 2.5-fold in the nuclear fraction, and this correlated with a significant increase in Sp1-DNA complex formation. Pretreatment of cells with the EGFR inhibitor AG1478 decreased Sp1-DNA binding (Di et al., 2012).

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

Infection of H292 cells with influenza A virus (IVA) at MOI=1 resulted in increased EGFR phosphorylation, peaking at 24 h. This was accompanied by activation of Sp-1 as shown by EMSA (Barbier et al., 2012). 

Treatment of primary bronchial epithelial cells with 10 nM TCDD resulted in maximal EGFR phosphorylation after 30 min. TCDD treatment also led to a time-dependent increase in MUC5AC transcriptional promoter activity, peaking between 6 and 12 h. Sp1 involvement was demonstrated by treatment with the Sp1 inhibitor mithramycin A (Lee et al., 2011).

Treatment with 20 ng/mL EGF or TGFa induced phosphorylation of Sp1, corresponding to a 2-3-fold increase in MUC2 and MUC5AC promoter activity, after 24 hours which was inhibited by 100 nM mithramycin A (a Sp1 inhibitor) (Perrais et al., 2002).

Treatment of H292 cells with a combination of 4 ng/mL TGFa and 25 µg/mL polyI:C resulted in a ca. 3-fold increase in EGFR phosphorylation at 1 h. At 12 h, MUC5AC mRNA expression was induced, intracellular MUC5AC protein expression was increased by nearly 30% and secretion of MUC5AC into the cell culture medium rose approx. 4-fold. MUC5AC mRNA expression could be completely abolished by the Sp1 inhibitor mithramycin A (500 nM) (Oyanagi et al., 2016).

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

EGFR-mediated activation of Sp1 was reported in mouse (Hammoud et al., 2009; Lee et al., 2010), rat (Merchant et al., 1995; Mortensen et al., 1997), dog (Ikari et al., 2009; Ford et al., 1997) and human (Di et al., 2012; Hewson et al., 2004; Lee et al., 2011; Perrais et al., 2002; Barbier et al., 2012; Oyanagi et al, 2016).


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

Allahverdian, S., Wang, A., Singhera, G.K., Wong, B.W., and Dorscheid, D.R. (2010). Sialyl Lewis X modification of the epidermal growth factor receptor regulates receptor function during airway epithelial wound repair. Clin Exp Allergy 40, 607-618.

Barbier, D., Garcia-Verdugo, I., Pothlichet, J., Khazen, R., Descamps, D., Rousseau, K., Thornton, D., Si-Tahar, M., Touqui, L., Chignard, M., et al. (2012). Influenza A Induces the Major Secreted Airway Mucin MUC5AC in a Protease–EGFR–Extracellular Regulated Kinase–Sp1–Dependent Pathway. Am J. Respir Cell Mol Biol 47, 149–157.

Burgel, P., and Nadel, J. (2004). Roles of epidermal growth factor receptor activation in epithelial cell repair and mucin production in airway epithelium. Thorax 59, 992-996.

Di, Y.P., Zhao, J., and Harper, R. (2012). Cigarette smoke induces MUC5AC protein expression through the activation of Sp1. J Biol Chem 287, 27948-27958.

Ford, M.G., Valle, J.D., Soroka, C.J., and Merchant, J.L. (1997). EGF receptor activation stimulates endogenous gastrin gene expression in canine G cells and human gastric cell cultures. J Clin Invest 99, 2762–2771.

Hackel, P.O., Zwick, E., Prenzel, N., and Ullrich, A. (1999). Epidermal growth factor receptors: critical mediators of multiple receptor pathways. Curr Opin Cell Biol 11, 184-189.

Higashiyama, S., Iwabuki, H., Morimoto, C., Hieda, M., Inoue, H., and Matsushita, N. (2008). Membrane-anchored growth factors, the epidermal growth factor family: Beyond receptor ligands. Cancer Sci 99, 214-220.

Hammoud, L., Burger, D.E., Lu, X., and Feng, Q. (2009). Tissue inhibitor of metalloproteinase-3 inhibits neonatal mouse cardiomyocyte proliferation via EGFR/JNK/SP-1 signaling. Am J Physiol Cell Physiol 296, C735–C745.

Hewson, C., Edbrooke, M., and Johnston, S. (2004). PMA induces the MUC5AC respiratory mucin in human bronchial epithelial cells, via PKC, EGF/TGF-alpha, Ras/Raf, MEK, ERK and Sp1-dependent mechanisms. J Mol Biol 344, 683–695.

Ikari, A., Atomi, K., Takiguchi, A., Yamazaki, Y., Miwa, M., and Sugatani, J. (2009). Epidermal growth factor increases claudin-4 expression mediated by Sp1 elevation in MDCK cells. Biochem Biophys Res Commun 384, 306–310.

Kim, S., Schein, A.J., and Nadel, J.A. (2005). E-cadherin promotes EGFR-mediated cell differentiation and MUC5AC mucin expression in cultured human airway epithelial cells. Am J Physiol Lung Cell Mol Physiol 289, L1049-L1060.

Lee, S.J., Kim, C.E., Seo, K.W., and Kim, C.D. (2010). HNE-induced 5-LO expression is regulated by NF-{kappa}B/ERK and Sp1/p38 MAPK pathways via EGF receptor in murine macrophages. Cardiovasc Res 88, 352–359.

Lee, Y.C., Oslund, K.L., Thai, P., Velichko, S., Fujisawa, T., Duong, T., Denison, M.S., and Wu, R. (2011). 2,3,7,8-Tetrachlorodibenzo-p-dioxin–Induced MUC5AC Expression. Am J Respir Cell Mol Biol 45, 270–276.

Lemjabbar, H., Li, D., Gallup, M., Sidhu, S., Drori, E., and Basbaum, C. (2003). Tobacco smoke-induced lung cell proliferation mediated by tumor necrosis factor alpha-converting enzyme and amphiregulin. J Biol Chem 278, 26202-26207.

Lu, X.-F., Li, E.-M., Du, Z.-P., Xie, J.-J., Guo, Z.-Y., Gao, S.-Y., Liao, L.-D., Shen, Z.-Y., Xie, D., and Xu, L.-Y. (2010). Specificity protein 1 regulates fascin expression in esophageal squamous cell carcinoma as the result of the epidermal growth factor/extracellular signal-regulated kinase signaling pathway activation. Cell Mol Life Sci CMLS 67, 3313–3329.

Merchant, J.L., Shiotani, A., Mortensen, E.R., Shumaker, D.K., and Abraczinskas, D.R. (1995). Epidermal growth factor stimulation of the human gastrin promoter requires Sp1. J Biol Chem 270, 6314–6319.

Mortensen, E.R., Marks, P.A., Shiotani, A., and Merchant, J.L. (1997). Epidermal growth factor and okadaic acid stimulate Sp1 proteolysis. J Biol Chem 272, 16540–16547.

Oyanagi, T., Takizawa, T., Aizawa, A., Solongo, O., Yagi, H., Nishida, Y., Koyama, H., Saitoh, A., and Arakawa, H. (2016). Suppression of MUC5AC expression in human bronchial epithelial cells by interferon-γ. Allergol Int 66, 75-82.

Perrais, M., Pigny, P., Copin, M., Aubert, J., and Van Seuningen, I. (2002). Induction of MUC2 and MUC5AC mucins by factors of the epidermal growth factor (EGF) family is mediated by EGF receptor/Ras/Raf/extracellular signal-regulated kinase cascade and Sp1. J Biol Chem 277, 32258–32267.

Van Winkle, L.S., Isaac, J.M., and Plopper, C.G. (1997). Distribution of epidermal growth factor receptor and ligands during bronchiolar epithelial repair from naphthalene-induced Clara cell injury in the mouse. Am J Pathol 151, 443.

Wu, D.Y.-c., Wu, R., Reddy, S.P., Lee, Y.C., and Chang, M.M.-J. (2007). Distinctive epidermal growth factor receptor/extracellular regulated kinase-independent and-dependent signaling pathways in the induction of airway mucin 5B and mucin 5AC expression by phorbol 12-myristate 13-acetate. Am J Pathol 170, 20-32.

Zheng, X.-L., Matsubara, S., Diao, C., Hollenberg, M.D., and Wong, N.C.W. (2001). Epidermal Growth Factor Induction of Apolipoprotein A-I Is Mediated by the Ras-MAP Kinase Cascade and Sp1. J Biol Chem 276, 13822–13829.