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Relationship: 3174

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

Decreased, INSL3 leads to Impaired inguinoscrotal phase

Upstream event

The causing Key Event (KE) in a Key Event Relationship (KER). More help

Decreased, INSL3

Downstream event

The responding Key Event (KE) in a Key Event Relationship (KER). More help

Impaired inguinoscrotal phase

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
Decreased Insulin-like peptide 3 (INSL3) leads to Malformation, cryptorchidism - maldescended testis	non-adjacent	High	Not Specified	John Frisch (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 Do not cite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 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
mammals	mammals	Moderate	NCBI

Sex Applicability

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

Sex	Evidence
Male	High

Life Stage Applicability

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

Term	Evidence
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

In this key event relationship we are focused on the decrease in Insulin-like 3 peptide (INSL3) gene expression, and corresponding impairment of inguinoscrotal phase of testes descent. Here we focus on the indirect relationship of gene expression to abnormal development. INSL3 is responsible for development of the gubernaculum and subsequent testicular descent via activation of the GREAT (LGR8) receptor. Literature suggests that androgen levels are responsible for proper development of the cranial suspensory ligament and the gubernaculum (Zimmerman et al. 1999; Nef and Parada 1999 Wilson et al. 2007), but whether testosterone and/or other androgens are the causative hormone(s) has not been determined.

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

This Key Event Relationship was developed as part of an Environmental Protection Agency effort to represent putative AOPs from peer-reviewed literature which were heretofore unrepresented in the AOP-Wiki. Palermo et al. (2021) focused on identifying Adverse Outcome Pathways associated with adverse male reproductive outcomes from phthalate exposure through review of existing literature, and provided initial network analysis.

Authors of KER 3174 did a further evaluation of published peer-reviewed literature to provide additional evidence in support of the key event relationship.

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

Predominantly in laboratory mammal studies, INSL3 gene expression has been studied via toxicant exposure as well as contrasting wild-type strains to strains with decreased INSL3 and related gene function, and consistently shown impairment of inguinoscrotal descent during development. INSL3 regulates the development of the gubernaculum and subsequent testicular descent through signalling activated by binding to GREAT (LGR8) receptor.

Empirical Evidence

Provides specific (citable) evidence that supports the idea of a change in the upstream KE (KEupstream) leading to, or being associated with, a subsequent change in the downstream KE (KEdownstream), assuming the perturbation of KEupstream is sufficient. More help

Species	Duration	Dose	Decreased INSL3?	Impaired inguinoscrotal phase?	Summary	Citation
Mouse (Mus musculus)	3 months	Knock-out gene study.	yes	yes	Mice, various cell lines with wild-type and knock-out gene expression of INSL3 and GREAT, decreased INSL3 expression resulting in impaired inguinoscrotal phase, identified GREAT (LGR8) as key receptor.	Bogatcheva et al. (2003)
Mouse (Mus musculus)	16 days	Knock-out gene study.	yes	yes	Mice, various cell lines with wild-type and knock-out gene expression of INSL3 and RXFP2, decreased INSL3 expression resulting in impaired inguinoscrotal phase.	Kaftanovskaya et al. (2011)
Mouse (Mus musculus)	6 weeks	Knock-out gene study.	yes	yes	Mice, various cell lines with wild-type and knock-out gene expression of INSL3, decreased INSL3 expression resulting in impaired inguinoscrotal phase.	Nef and Parada (1999)
Rat (Rattus norvegicus)	8 days	1 g/kg/day DEHP, DBP, BBP in utero	yes	yes	Sprague-Dawley rats, DEHP, DBP, BBP decreased INSL3 expression resulting in impaired inguinoscrotal phase; 200 mg/kg/d vinclozin, 100 mg/kg/d linuron, 250 mg/kg/d prochlaz did not affect INSL3 as predicted.	Wilson et al. (2004)
Rat (Rattus norvegicus)	120 days	750 mg/kg/day DEHP in utero, followed through development	yes	yes	Wistar rats, decreased INSL3 expression resulting in impaired inguinoscrotal phase; as predicted Sprague-Dawley rats had neither decreased INSL3 nor impaired inguinoscrotal phase.	Wilson et al. (2007)
Mouse (Mus musculus)	12 weeks	Knock-out gene study.	yes	yes	Mice, various cell lines with wild-type and knock-out gene expression of INSL3, decreased INSL3 expression resulting in impaired inguinoscrotal phase.	Zimmerman et al. (1999)

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

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

Quantitative Understanding of the Linkage

Captures information that helps to define how much change in the upstream KE, and/or for how long, is needed to elicit a detectable and defined change in the downstream KE. More help

Response-response Relationship

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

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

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

Life Stage: Occurs during development.

Sex: Applies to males.

Taxonomic: Most representative studies have been done in mammals (humans, lab mice, lab rats); plausible for all vertebrates.

References

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

Bogatcheva, N.V., Truong, A., Feng, S., Engel, W., Adham, I.M., and Agoulnik, A.I. 2003. GREAT/LGR8 Is the Only Receptor for Insulin-Like 3 Peptide. Molecular Endocrinology 17(12):2639–2646.

Kaftanovskaya, E.M., Feng, S., Huang, Z., Tan, Y., Barbara, A.M., Kaur, S., Troung, A., Gorlov, I.P., and Agoulnik, A.I. 2011. Suppression of Insulin-Like3 Receptor Reveals the Role of β-Catenin and Notch Signaling in Gubernaculum Development. Molecular Endocrinology 25: 170–183.

Nef, S. and Parada, L.F. 1999. Cryptorchidism in mice mutant for Insl3. Nature Genetics 22: 295-299.

Palermo, C.M., Foreman, J.E., Wikoff, D.S., and Lea, I. 2021. Development of a putative adverse outcome pathway network for male rat reproductive tract abnormalities with specific considerations for the androgen sensitive window of development. Current Research in Toxicology 2: 254–271.

Wilson, V.S., Lambright, C., Furr, J., Ostby, J., Wood, C., Held, G., and Gray, Jr., L.E. 2004. Phthalate ester-induced gubernacular lesions are associated with reduced insl3 gene expression in the fetal rat testis. Toxicology Letters 146: 207–215.

Wilson, V.S., Howdeshell, K.L., Lambright, C.S., Furr, J., and Gray, Jr., L.E. 2007. Differential expression of the phthalate syndrome in male Sprague–Dawley and Wistar rats after in utero DEHP exposure. Toxicology Letters 170: 177–184.

Zimmermann, S., Steding, G., Emmen, J.M.A., Brinkmann, A.O., Nayernia, K., Holstein, A.F., Engel, W., and Adham, I.M. 1999. Targeted Disruption of the Insl3 Gene Causes Bilateral Cryptorchidism. Molecular Endocrinology 13(5): 681-691.

NOTE: Italics indicate edits from John Frisch