Multiple functions of let-23, a Caenorhabditis elegans receptor tyrosine kinase gene required for vulval induction.
The let-23 gene, which encodes a putative tyrosine kinase of the epidermal growth factor (EGF) receptor subfamily, has multiple functions during Caenorhabditis elegans development. We show that let-23 function is required for vulval precursor cells (VPCs) to respond to the signal that induces vulval differentiation: a complete loss of let-23 function results in no induction. However, some let-23 mutations that genetically reduce but do not eliminate let-23 function result in VPCs apparently hypersensitive to inductive signal: as many as five of six VPCs can adopt vulval fates, in contrast to the three that normally do. These results suggest that the let-23 receptor tyrosine kinase controls two opposing pathways, one that stimulates vulval differentiation and another that negatively regulates vulval differentiation. Furthermore, analysis of 16 new let-23 mutations indicates that the let-23 kinase functions in at least five tissues. Since various let-23 mutant phenotypes can be obtained independently, the let-23 gene is likely to have tissue-specific functions.
Aroian
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RV
Howard Hughes Medical Institute, Division of Biology, California Institute of Technology, Pasadena 91125.
Sternberg
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PW
D000483:Alleles; D000818:Animals; D002107:Caenorhabditis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D005816:Genetic Complementation Test; D009154:Mutation; D009928:Organ Specificity / Q000235:genetics; D010641:Phenotype; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D014844:Vulva / Q000166:cytology / Q000254:growth & development*
D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases