FGF signaling regulates Wnt ligand expression to control vulval cell lineage polarity in C. elegans.
The interpretation of extracellular cues leading to the polarization of intracellular components and asymmetric cell divisions is a fundamental part of metazoan organogenesis. The Caenorhabditis elegans vulva, with its invariant cell lineage and interaction of multiple cell signaling pathways, provides an excellent model for the study of cell polarity within an organized epithelial tissue. Here, we show that the fibroblast growth factor (FGF) pathway acts in concert with the Frizzled homolog LIN-17 to influence the localization of SYS-1, a component of the Wnt/β-catenin asymmetry pathway, indirectly through the regulation of cwn-1. The source of the FGF ligand is the primary vulval precursor cell (VPC) P6.p, which controls the orientation of the neighboring secondary VPC P7.p by signaling through the sex myoblasts (SMs), activating the FGF pathway. The Wnt CWN-1 is expressed in the posterior body wall muscle of the worm as well as in the SMs, making it the only Wnt expressed on the posterior and anterior sides of P7.p at the time of the polarity decision. Both sources of cwn-1 act instructively to influence P7.p polarity in the direction of the highest Wnt signal. Using single molecule fluorescence in situ hybridization, we show that the FGF pathway regulates the expression of cwn-1 in the SMs. These results demonstrate an interaction between FGF and Wnt in C. elegans development and vulval cell lineage polarity, and highlight the promiscuous nature of Wnts and the importance of Wnt gradient directionality within C. elegans.
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Paul J
PJ
Minor
Ting-Fang
TF
He
Chang Ho
CH
Sohn
Anand R
AR
Asthagiri
Paul W
PW
Sternberg
D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D019070:Cell Lineage; D016764:Cell Polarity; D005260:Female; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008024:Ligands; D008954:Models, Biological; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D021381:Protein Transport; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014844:Vulva / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D008024:Ligands; D051153:Wnt Proteins; D051176:beta Catenin; D049452:Green Fluorescent Proteins; D005346:Fibroblast Growth Factors
C. elegans; Cell polarity; FGF; Vulval development; Wnt