Wnt and EGF pathways act together to induce C. elegans male hook development

Dev Biol. 2009 Mar 15;327(2):419-32. doi: 10.1016/j.ydbio.2008.12.023. Epub 2008 Dec 30.


Comparative studies of vulva development between Caenorhabditis elegans and other nematode species have provided some insight into the evolution of patterning networks. However, molecular genetic details are available only in C. elegans and Pristionchus pacificus. To extend our knowledge on the evolution of patterning networks, we studied the C. elegans male hook competence group (HCG), an equivalence group that has similar developmental origins to the vulval precursor cells (VPCs), which generate the vulva in the hermaphrodite. Similar to VPC fate specification, each HCG cell adopts one of three fates (1 degree, 2 degrees, 3 degrees), and 2 degrees HCG fate specification is mediated by LIN-12/Notch. We show that 2 degrees HCG specification depends on the presence of a cell with the 1 degree fate. We also provide evidence that Wnt signaling via the Frizzled-like Wnt receptor LIN-17 acts to specify the 1 degree and 2 degrees HCG fate. A requirement for EGF signaling during 1 degree fate specification is seen only when LIN-17 activity is compromised. In addition, activation of the EGF pathway decreases dependence on LIN-17 and causes ectopic hook development. Our results suggest that WNT plays a more significant role than EGF signaling in specifying HCG fates, whereas in VPC specification EGF signaling is the major inductive signal. Nonetheless, the overall logic is similar in the VPCs and the HCG: EGF and/or WNT induce a 1 degree lineage, and LIN-12/NOTCH induces a 2 degrees lineage. Wnt signaling is also required for execution of the 1 degree and 2 degrees HCG lineages. lin-17 and bar-1/beta-catenin are preferentially expressed in the presumptive 1 degree cell P11.p. The dynamic subcellular localization of BAR-1-GFP in P11.p is concordant with the timing of HCG fate determination.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / metabolism
  • Body Patterning / physiology*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Caenorhabditis elegans* / anatomy & histology
  • Caenorhabditis elegans* / embryology
  • Caenorhabditis elegans* / metabolism
  • Cell Lineage
  • Embryonic Induction
  • Epidermal Growth Factor / genetics
  • Epidermal Growth Factor / metabolism*
  • Frizzled Receptors / genetics
  • Frizzled Receptors / metabolism
  • Male
  • Mutation
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction / physiology*
  • Wnt Proteins / genetics
  • Wnt Proteins / metabolism*


  • Biomarkers
  • Caenorhabditis elegans Proteins
  • Frizzled Receptors
  • Recombinant Fusion Proteins
  • Wnt Proteins
  • Epidermal Growth Factor