title: Reciprocal signaling by Wnt and Notch specifies a muscle precursor in the C. elegans embryo.
abstract: The MS blastomere produces one-third of the body wall muscles (BWMs) in the C. elegans embryo. MS-derived BWMs require two distinct cell-cell interactions, the first inhibitory and the second, two cell cycles later, required to overcome this inhibition. The inductive interaction is not required if the inhibitory signal is absent. Although the Notch receptor GLP-1 was implicated in both interactions, the molecular nature of the two signals was unknown. We now show that zygotically expressed MOM-2 (Wnt) is responsible for both interactions. Both the inhibitory and the activating interactions require precise spatiotemporal expression of zygotic MOM-2, which is dependent upon two distinct Notch signals. In a Notch mutant defective only in the inductive interaction, MS-derived BWMs can be restored by preventing zygotic MOM-2 expression, which removes the inhibitory signal. Our results suggest that the inhibitory interaction ensures the differential lineage specification of MS and its sister blastomere, whereas the inductive interaction promotes the expression of muscle-specifying genes by modulating TCF and β-catenin levels. These results highlight the complexity of cell fate specification by cell-cell interactions in a rapidly dividing embryo.
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Scott M
authors.identifier: 0000-0002-3764-2811
authors.initials: SM
authors.lastname: Robertson
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Medina
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Marieke
authors.initials: M
authors.lastname: Oldenbroek
authors.affiliation: Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA rueyling.lin@utsouthwestern.edu.
authors.forename: Rueyling
authors.identifier: 0000-0001-6673-5286
authors.initials: R
authors.lastname: Lin
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001757:Blastomeres / Q000166:cytology / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D019070:Cell Lineage / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004627:Embryonic Induction / Q000235:genetics / Q000502:physiology; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009132:Muscles / Q000196:embryology; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D051820:TCF Transcription Factors / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000235:genetics / Q000502:physiology; D015053:Zygote / Q000166:cytology / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D050980:GATA Transcription Factors; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D051880:Receptors, Notch; D015222:Sodium Channels; D020825:T-Box Domain Proteins; D051820:TCF Transcription Factors; D014157:Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; C109211:END-1 protein, C elegans; C060620:Glp-1 protein, C elegans; C518000:MOM-2 protein, C elegans; C514535:TBX-35 protein, C elegans; C489774:apx-1 protein, C elegans; C428453:ref-1 protein, C elegans; C073702:skn-1 protein, C elegans
keywords: Body wall muscles; C. elegans; MS blastomere; Notch; Wnt; glp-1; mom-2