title: beta-Catenin asymmetries after all animal/vegetal- oriented cell divisions in Platynereis dumerilii embryos mediate binary cell-fate specification.
abstract: In response to Wnt signaling during animal development, beta-catenin accumulates in nuclei to mediate the transcriptional activation of target genes. Here, we show that a highly conserved beta-catenin in the annelid Platynereis dumerilii exhibits a reiterative, nearly universal embryonic pattern of nuclear accumulation remarkably similar to that observed in the nematode Caenorhabditis elegans. Platynereis exhibits beta-catenin sister-cell asymmetries after all cell divisions that occur along the animal/vegetal axis beginning early in embryogenesis, but not after two transverse divisions that establish bilateral symmetry in the trunk. Moreover, ectopic activation of nuclear beta-catenin accumulation in Platynereis causes animal-pole sister cells, which normally have low nuclear beta-catenin levels, to adopt the fate of their vegetal-pole sisters, which normally have high nuclear beta-catenin levels. The presence of reiterative and functionally important beta-catenin asymmetries in two distantly related animal phyla suggests an ancient metazoan origin of a beta-catenin-mediated binary cell-fate specification module.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Stephan Q
authors.initials: SQ
authors.lastname: Schneider
authors.forename: Bruce
authors.initials: B
authors.lastname: Bowerman
mesh_terms: D000818:Animals; D019070:Cell Lineage / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011077:Polychaeta / Q000166:cytology / Q000196:embryology*; D015398:Signal Transduction / Q000502:physiology*; D013692:Telophase / Q000502:physiology*; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D051153:Wnt Proteins; D051176:beta Catenin