Competence and commitment of Caenorhabditis elegans vulval precursor cells.
Multipotent Caenorhabditis elegans vulval precursor cells (VPCs) choose among three fates (1 degrees, 2 degrees, and 3 degrees ) in response to two intercellular signals: the EGF family growth factor LIN-3 induces 1 degrees fates at high levels and 2 degrees fates at low levels; and a signal via the receptor LIN-12 induces 2 degrees fates. If the level of LIN-3 signal is reduced by a lin-3 hypomorphic mutation, the daughters of the VPC closest to the anchor cell (AC), P6.p, are induced by the AC. By expressing LIN-3 as a function of time in LIN-3-deficient animals, we find that both VPCs and the daughters of VPCs are competent to respond to LIN-3, and VPC daughters lose competence after fusing with the hypodermis. We also demonstrate that the daughters of VPCs specified to be 2 degrees can respond to LIN-3, indicating that 2 degrees VPCs are not irreversibly committed. We propose that maintenance of VPC competence after the first cell cycle and the prioritization of the 1 degrees fate help ensure that P6.p will become 1 degrees. This mechanism of competence regulation might have been maintained from ancestral nematode species that used induction both before and after VPC division and serves to maximize the probability that a functional vulva is formed.
Howard Hughes Medical Institute and Division of Biology, California Institute of Technology, Pasadena, California, 91125, USA.
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D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D002453:Cell Cycle; D019070:Cell Lineage; D004627:Embryonic Induction; D004815:Epidermal Growth Factor; D005260:Female; D015801:Helminth Proteins / Q000378:metabolism / Q000494:pharmacology; D006918:Hydroxyurea / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008957:Models, Genetic; D010375:Pedigree; D051880:Receptors, Notch; D015398:Signal Transduction; D013234:Stem Cells; D013696:Temperature; D013997:Time Factors; D014844:Vulva / Q000166:cytology / Q000196:embryology* / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; C082460:Lin-12 protein, C elegans; D008565:Membrane Proteins; D051880:Receptors, Notch; C075912:Lin-3 protein, C elegans; D004815:Epidermal Growth Factor; D006918:Hydroxyurea