title: C. elegans Rb, NuRD, and Ras regulate lin-39-mediated cell fusion during vulval fate specification.
abstract: The tumor suppressor Rb and the NuRD (nucleosome remodeling and histone deacetylation) complex have been implicated in transcriptional repression during cell cycle progression and cell fate specification. The Rb/E2F complex physically interacts with and thus recruits the NuRD complex to actively repress transcription. Caenorhabditis elegans counterparts of Rb, E2F/DP, and some NuRD complex components appear to function in a common class B synthetic Multivulva (synMuv) pathway to antagonize RTK/Ras signaling during vulval fate specification. Therefore, it has been suggested that they function together in a single complex to repress vulva-specific gene transcription. However, little is known about the in vivo interactions between these class B synMuv genes and their relationships with other pathways in specific cellular processes during vulval development. We show that C. elegans Rb/E2F and NuRD complexes antagonize Ras activity by controlling a lin-39 Hox-mediated cell fusion event that regulates the competence of vulval cells. Interestingly, Rb/E2F and NuRD complexes exhibit very different genetic properties. While the NuRD complex negatively regulates lin-39 Hox activity, likely by downregulating its expression, RB/E2F appears to play dual roles in regulating lin-39: a negative role in controlling its activity and a previously uncharacterized positive role in regulating its expression.
authors.affiliation: Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Han
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D002459:Cell Fusion; D019070:Cell Lineage; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D005260:Female; D017238:Genes, Helminth; D006655:Histone Deacetylases / Q000502:physiology*; D018398:Homeodomain Proteins / Q000502:physiology*; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D014157:Transcription Factors / Q000502:physiology*; D014844:Vulva / Q000166:cytology* / Q000254:growth & development; D018631:ras Proteins / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D018398:Homeodomain Proteins; D014157:Transcription Factors; C493765:efl-1 protein, C elegans; C108673:lin-39 protein, C elegans; D006655:Histone Deacetylases; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D018631:ras Proteins