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Event: 1646

Key Event Title

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

Frizzled activation

Short name

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Frizzled activation

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Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. More help

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

Cell term
cell

Organ term

Organ term
organ

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

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

Term	Scientific Term	Evidence	Link
Homo sapiens	Homo sapiens	High	NCBI

Life Stages

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

Life stage	Evidence
All life stages	High

Sex Applicability

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

Term	Evidence
Unspecific	High

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

Wnt ligands bind to Frizzled (FZD) receptors which are seven transmembrane-domain protein receptors (Nile, Mukund, Stanger, Wang, & Hannoush, 2017). At least 10 FZD receptors are identified in human cells. FZD receptor is activated by Wnt ligand binding (MacDonald, Tamai, & He, 2009).

Dishevelled (DVL), a positive regulator of Wnt signaling, form the complex with FZD and lead to trigger the Wnt signaling together with Wnt coreceptor low-density lipoprotein (LDL) receptor-related protein 6 (LRP6) (Clevers & Nusse, 2012; X. Jiang, Charlat, Zamponi, Yang, & Cong, 2015). DVL, however, has a controversial role to promote Wnt receptor degradation (X. Jiang et al., 2015). Meanwhile, DVL-dependent regulation of FZD level is involved in mTORC1 signaling suppression via Wnt/beta-catenin signaling (H. Zeng et al., 2018).

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

Frizzled receptor protein level on the cell surface is measured by flow cytometry with pan-FZD antibody (X. Jiang et al., 2015; H. Zeng et al., 2018).
DVL protein level is measured by immunoblotting with anti-DVL2 antibody (H. Zeng et al., 2018).
Fzd mRNA level is measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR) (H. Zeng et al., 2018).

Domain of Applicability

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

Oligomerization of FZD and low-density lipoprotein receptor-related protein 5/6 (LRP5/6) activates Wnt/beta-catenin signaling in Homo sapiens. (Hua et al., 2018).

References

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

Bhanot, P., Brink, M., Samos, C. H., Hsieh, J.-C., Wang, Y., Macke, J. P., . . . Nusse, R. (1996). A new member of the frizzled family from Drosophila functions as a Wingless receptor. Nature, 382, 225. Retrieved from https://doi.org/10.1038/382225a0. doi:10.1038/382225a0

Clevers, H., & Nusse, R. (2012). Wnt/beta-catenin signaling and disease. Cell, 149(6), 1192-1205. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22682243. doi:10.1016/j.cell.2012.05.012

Hua, Y., Yang, Y., Li, Q., He, X., Zhu, W., Wang, J., & Gan, X. (2018). Oligomerization of Frizzled and LRP5/6 protein initiates intracellular signaling for the canonical WNT/beta-catenin pathway. J Biol Chem, 293(51), 19710-19724. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/30361437. doi:10.1074/jbc.RA118.004434

Janda, C. Y., Waghray, D., Levin, A. M., Thomas, C., & Garcia, K. C. (2012). Structural basis of Wnt recognition by Frizzled. Science, 337(6090), 59-64. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22653731. doi:10.1126/science.1222879

Jiang, X., Charlat, O., Zamponi, R., Yang, Y., & Cong, F. (2015). Dishevelled promotes Wnt receptor degradation through recruitment of ZNRF3/RNF43 E3 ubiquitin ligases. Mol Cell, 58(3), 522-533. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/25891077. doi:10.1016/j.molcel.2015.03.015

MacDonald, B. T., Tamai, K., & He, X. (2009). Wnt/beta-catenin signaling: components, mechanisms, and diseases. Dev Cell, 17(1), 9-26. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/19619488. doi:10.1016/j.devcel.2009.06.016

Nile, A. H., Mukund, S., Stanger, K., Wang, W., & Hannoush, R. N. (2017). Unsaturated fatty acyl recognition by Frizzled receptors mediates dimerization upon Wnt ligand binding. Proc Natl Acad Sci U S A, 114(16), 4147-4152. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/28377511. doi:10.1073/pnas.1618293114

Zeng, H., Lu, B., Zamponi, R., Yang, Z., Wetzel, K., Loureiro, J., . . . Cong, F. (2018). mTORC1 signaling suppresses Wnt/beta-catenin signaling through DVL-dependent regulation of Wnt receptor FZD level. Proc Natl Acad Sci U S A, 115(44), E10362-E10369. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/30297426. doi:10.1073/pnas.1808575115