title: HOM-C genes, Wnt signaling and axial patterning in the C. elegans posterior ventral epidermis.
abstract: Wnt signaling and HOM-C/Hox genes pattern cell fate along the anterior/posterior axis in many animals. In general, Wnt signaling participates in establishing the anterior/posterior axis, whereas HOM-C genes confer regional identities to cells along the axis. However, recent work in non-bilaterial metazoans suggests that the ancestral patterning system relied on Wnts, with a later co-option of HOM-C genes to replace Wnts in regional patterning. Here we provide direct experimental support for this model from C. elegans, where a regional Wnt patterning system is uncovered in HOM-C gene mutants. Anterior/posterior patterning of P11/P12 cell fate in the C. elegans tail is normally dependent on the HOM-C gene egl-5/Abdominal-B. If the HOM-C gene mab-5/fushi tarazu is also mutant, however, a Wnt signal can promote P12 fate in the absence of egl-5. Furthermore, transcription of egl-5 in the P12.pa cell is influenced by an autoregulatory element that is essential in wild type, but not in mab-5 egl-5 double mutants, identifying regulatory parallels between P12 cell fate specification and egl-5 transcriptional regulation in the P12 lineage. Together, our results identify complex regulatory relationships among signaling pathways and HOM-C genes, and uncover a layering of patterning systems that may reflect their evolutionary history.
authors.affiliation: Molecular, Cellular and Developmental Biology Program, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Rashmi P
authors.initials: RP
authors.lastname: Kulkarni
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Hill
authors.forename: Helen M
authors.initials: HM
authors.lastname: Chamberlin
mesh_terms: D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000187:drug effects; D017173:Caenorhabditis elegans / Q000166:cytology / Q000187:drug effects / Q000196:embryology* / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002459:Cell Fusion; D019070:Cell Lineage / Q000187:drug effects; D017124:Conserved Sequence; D004742:Enhancer Elements, Genetic / Q000235:genetics; D000078404:Epidermal Cells; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004817:Epidermis / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005801:Genes, Homeobox; D017930:Genes, Reporter; D006706:Homeostasis / Q000187:drug effects; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D019076:Transgenes; D051153:Wnt Proteins / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D051153:Wnt Proteins; D004815:Epidermal Growth Factor