Event: 1754

Key Event Title


Sustained tissue damage / macrophage activation/ porcupine-induced Wnt secretion

Short name


Sustained tissue damage / macrophage activation/ porcupine-induced Wnt secretion

Biological Context


Level of Biological Organization

Organ term


Key Event Components


Process Object Action
Wnt protein secretion protein-serine O-palmitoleoyltransferase porcupine increased

Key Event Overview

AOPs Including This Key Event





Taxonomic Applicability


Term Scientific Term Evidence Link
Homo sapiens Homo sapiens High NCBI

Life Stages


Life stage Evidence
All life stages Moderate

Sex Applicability


Term Evidence
Unspecific High

Key Event Description


Porcupine, which is a trans-membrane endoplasmic reticulum O-acyl transferase, which is important for the secretion of Wnt ligands(Saha et al., 2016a). WNTs are secreted proteins that contain 22-24 conserved cysteine residues (Foulquier et al., 2018). The WNT molecules consist of molecular families including WNT1, WNT2, WNT2B/WNT13, WNT3, WNT4, WNT5A, WNT5B, WNT6, WNT7A, WNT7B, WNT8A, WNT8B, WNT10B, WNT11 and WNT16. (Clevers & Nusse, 2012; M. Katoh, 2001; Kusserow et al., 2005)

Wnt proteins consists of 350-400 amino acids (Saito-Diaz et al., 2013).

WNT ligands are known to trigger at least three different downstream signaling cascades including canonical WNT/beta-catenin signaling pathway, non-canonical WNT/Ca2+ pathway and planer cell polarity (PCP) pathway(De, 2011; Lai, Chien, & Moon, 2009; Willert & Nusse, 2012). WNTs bind to Frizzled proteins, which are seven-pass transmembrane receptors with an extracellular N-terminal cysteine-rich domain (Bhanot et al., 1996; Clevers, 2006). Wnt signaling begins with the binding of Wnt ligand towards the Frizzled receptors (Mohammed et al., 2016).

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). 

How It Is Measured or Detected


  • Secretion of WNT requires a number of other dedicated factors including the sortin receptor Wntless (WLS), which binds to Wnt and escorts it to the cell surface (Banziger et al., 2006; Ching & Nusse, 2006)
  • Wnt signaling is activated by the gene mutations of the signaling components (Ziv et al., 2017).
  • Wnt1, Wnt3a and Wnt5a protein expression are measured by immunoblotting using antibodies for Wnt1, Wnt3a and Wnt5a, respectively (J. Du et al., 2016; B. Wang et al., 2017).
  • WNT2, of which expression is detected by quantitative PCR, immunoblotting and immunohistochemistry, induces EMT (Zhou et al., 2016).
  • Frizzled receptor protein level on the cell surface is measured by flow cytometry with pan-FZD antibody (Jiang et al., 2015; Zeng et al., 2018). DVL protein level is measured by immunoblotting with anti-DVL2 antibody (Zeng et al., 2018).
  • Fzd mRNA level is measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR) (Zeng et al., 2018).
  • The up-regulation of WNT ligand expression occurs in Homo sapiens (B. Wang et al., 2017).
  • The Wnt genes play an important roles in the secretion from cells, glycosylation and tight association with the cell surface and extracellular matrix in Drosophila melanogaster (Willert & Nusse, 2012).

Domain of Applicability


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).

Evidence for Perturbation by Stressor


Radiation induces porcupine-induced Wnt secretion in macrophage (Saha et al., 2016a).



Banziger, C., Soldini, D., Schutt, C., Zipperlen, P., Hausmann, G., & Basler, K. (2006). Wntless, a conserved membrane protein dedicated to the secretion of Wnt proteins from signaling cells. Cell, 125(3), 509-522. doi:10.1016/j.cell.2006.02.049

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. doi:10.1038/382225a0

Ching, W., & Nusse, R. (2006). A dedicated Wnt secretion factor. Cell, 125(3), 432-433. doi:10.1016/j.cell.2006.04.018

Clevers, H. (2006). Wnt/beta-catenin signaling in development and disease. Cell, 127(3), 469-480. doi:10.1016/j.cell.2006.10.018

Clevers, H., & Nusse, R. (2012). Wnt/beta-catenin signaling and disease. Cell, 149(6), 1192-1205. doi:10.1016/j.cell.2012.05.012

De, A. (2011). Wnt/Ca2+ signaling pathway: a brief overview. Acta Biochim Biophys Sin (Shanghai), 43(10), 745-756. doi:10.1093/abbs/gmr079

Du, J., Zu, Y., Li, J., Du, S., Xu, Y., Zhang, L., . . . Yang, C. (2016). Extracellular matrix stiffness dictates Wnt expression through integrin pathway. Sci Rep, 6, 20395. doi:10.1038/srep20395

Foulquier, S., Daskalopoulos, E. P., Lluri, G., Hermans, K. C. M., Deb, A., & Blankesteijn, W. M. (2018). WNT Signaling in Cardiac and Vascular Disease. Pharmacol Rev, 70(1), 68-141. doi:10.1124/pr.117.013896

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. doi:10.1074/jbc.RA118.004434

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. doi:10.1016/j.molcel.2015.03.015

Katoh, M. (2001). Molecular cloning and characterization of human WNT3. International journal of oncology, 19(5), 977-982. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/11604997

Kusserow, A., Pang, K., Sturm, C., Hrouda, M., Lentfer, J., Schmidt, H. A., . . . Holstein, T. W. (2005). Unexpected complexity of the Wnt gene family in a sea anemone. Nature, 433(7022), 156-160. doi:10.1038/nature03158

Lai, S. L., Chien, A. J., & Moon, R. T. (2009). Wnt/Fz signaling and the cytoskeleton: potential roles in tumorigenesis. Cell Res, 19(5), 532-545. doi:10.1038/cr.2009.41

MacDonald, B. T., Tamai, K., & He, X. (2009). Wnt/beta-catenin signaling: components, mechanisms, and diseases. Dev Cell, 17(1), 9-26. doi:10.1016/j.devcel.2009.06.016

Mohammed, M. K., Shao, C., Wang, J., Wei, Q., Wang, X., Collier, Z., . . . Lee, M. J. (2016). Wnt/beta-catenin signaling plays an ever-expanding role in stem cell self-renewal, tumorigenesis and cancer chemoresistance. Genes Dis, 3(1), 11-40. doi:10.1016/j.gendis.2015.12.004

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. doi:10.1073/pnas.1618293114

Saha, S., Aranda, E., Hayakawa, Y., Bhanja, P., Atay, S., Brodin, N. P., . . . Pollard, J. W. (2016). Macrophage-derived extracellular vesicle-packaged WNTs rescue intestinal stem cells and enhance survival after radiation injury. Nature Communications, 7(1), 13096. doi:10.1038/ncomms13096

Saito-Diaz, K., Chen, T. W., Wang, X., Thorne, C. A., Wallace, H. A., Page-McCaw, A., & Lee, E. (2013). The way Wnt works: components and mechanism. Growth Factors, 31(1), 1-31. doi:10.3109/08977194.2012.752737

Wang, B., Tang, Z., Gong, H., Zhu, L., & Liu, X. (2017). Wnt5a promotes epithelial-to-mesenchymal transition and metastasis in non-small-cell lung cancer. Biosci Rep, 37(6). doi:10.1042/BSR20171092

Willert, K., & Nusse, R. (2012). Wnt proteins. Cold Spring Harb Perspect Biol, 4(9), a007864. doi:10.1101/cshperspect.a007864

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. doi:10.1073/pnas.1808575115

Zhou, Y., Huang, Y., Cao, X., Xu, J., Zhang, L., Wang, J., . . . Zheng, M. (2016). WNT2 Promotes Cervical Carcinoma Metastasis and Induction of Epithelial-Mesenchymal Transition. PLoS One, 11(8), e0160414. doi:10.1371/journal.pone.0160414

Ziv, E., Yarmohammadi, H., Boas, F. E., Petre, E. N., Brown, K. T., Solomon, S. B., . . . Erinjeri, J. P. (2017). Gene Signature Associated with Upregulation of the Wnt/beta-Catenin Signaling Pathway Predicts Tumor Response to Transarterial Embolization. J Vasc Interv Radiol, 28(3), 349-355 e341. doi:10.1016/j.jvir.2016.11.004