title: An inductive interaction in 4-cell stage C. elegans embryos involves APX-1 expression in the signalling cell.
abstract: During the 4-cell stage of C. elegans embryogenesis, the P2 blastomere provides a signal that allows two initially equivalent sister blastomeres, called ABa and ABp, to adopt different fates. Preventing P2 signalling in wild-type embryos results in defects in ABp development that are similar to those caused by mutations in the glp-1 and apx-1 genes, which are homologs of the Drosophila genes Notch and Delta, respectively. Previous studies have shown that GLP-1 protein is expressed in 4-cell stage embryos in both ABa and ABp. In this report, we show that APX-1 protein is expressed in the P2 blastomere and that a temperature-sensitive apx-1 mutant has a temperature-sensitive period between the 4-cell and 8-cell stages. We propose that APX-1 is part or all of the P2 signal that induces ABp to adopt a fate different than ABa.
authors.affiliation: Molecular and Cellular Biology Program, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Mickey
authors.forename: C C
authors.initials: CC
authors.lastname: Mello
authors.forename: M K
authors.initials: MK
authors.lastname: Montgomery
authors.forename: A
authors.initials: A
authors.lastname: Fire
authors.forename: J R
authors.initials: JR
authors.lastname: Priess
mesh_terms: D000818:Animals; D001757:Blastomeres / Q000502:physiology; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D004627:Embryonic Induction; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D012313:RNA; D015398:Signal Transduction; D015222:Sodium Channels
chemical_list: D029742:Caenorhabditis elegans Proteins; D008565:Membrane Proteins; D015222:Sodium Channels; C489774:apx-1 protein, C elegans; D012313:RNA