Conservation and diversification of Wnt signaling function during the evolution of nematode vulva development.
Cell-fate specification and cell-cell signaling have been well studied during vulva development in Caenorhabditis elegans and provide a paradigm in evolutionary developmental biology. Pristionchus pacificus has been developed as a 'satellite' organism with an integrated physical and genetic map that allows detailed comparisons to C. elegans. A common aspect of vulva formation in both species is the polarization of the P7.p lineage, which is responsible for vulval symmetry. In C. elegans, Wnt signaling is crucial for P7.p cell-fate patterning; nothing is known about vulval symmetry in P. pacificus. We isolated mutations that disrupt polarization of the P7.p lineage in P. pacificus and found that the corresponding gene encodes a Frizzled-like molecule. In addition, mutations in Ppa-lin-17 (encoding Frizzled) and morpholino knock-down of Ppa-lin-44 (encoding Wnt), Ppa-egl-20 (encoding Wnt), Ppa-mig-5 (encoding Dsh), Ppa-apr-1 (encoding APC) and Ppa-bar-1 (encoding beta-catenin) results in gonad-independent vulva differentiation, indicating that these genes have a role in a negative signaling process. In contrast, in C. elegans, Wnt signaling has a positive role in vulva induction, and mutations in bar-1 result in a hypoinduced phenotype. Therefore, whereas the molecular mechanisms that generate vulval symmetry are conserved, the genetic control of vulva induction diversified during evolution.
Zheng
Min
M
Max-Planck Institut für Entwicklungsbiologie, Abteilung Evolutionsbiologie, Spemannstrasse 37-39, D-72076 Tübingen, Germany.
Messerschmidt
Daniel
D
Jungblut
Benno
B
Sommer
Ralf J
RJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014844:Vulva / Q000254:growth & development*; D051153:Wnt Proteins
D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051153:Wnt Proteins