β-Catenin Asymmetries after All Animal/Vegetal- Oriented Cell Divisions in Platynereis dumerilii Embryos Mediate Binary Cell-Fate Specification

• Published in: Developmental cell Vol. 13; no. 1; pp. 73 - 86
• Main Authors: Schneider, Stephan Q., Bowerman, Bruce
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 01.07.2007; Cell Press
• Subjects: Animals; Annelida; beta Catenin - metabolism; Biological and medical sciences; Caenorhabditis elegans; Cell cycle, cell proliferation; Cell differentiation, maturation, development, hematopoiesis; Cell Lineage - physiology; Cell Nucleus - physiology; Cell physiology; DEVBIO; Embryo, Nonmammalian - cytology; Embryo, Nonmammalian - physiology; EVO_ECOL; Evolution, Molecular; Fundamental and applied biological sciences. Psychology; Metazoa; Molecular and cellular biology; Molecular Sequence Data; Nematoda; Phylogeny; Platynereis dumerilii; Polychaeta - cytology; Polychaeta - embryology; Signal Transduction - physiology; Telophase - physiology; Wnt Proteins - metabolism; DEVBIO; EVO_ECOL; Asymmetry; Cell fate; β Catenin; Cell division; Development; Animal vegetal axis; Invertebrata; Annelida
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2007.05.002

In response to Wnt signaling during animal development, β-catenin accumulates in nuclei to mediate the transcriptional activation of target genes. Here, we show that a highly conserved β-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 β-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 β-catenin accumulation in Platynereis causes animal-pole sister cells, which normally have low nuclear β-catenin levels, to adopt the fate of their vegetal-pole sisters, which normally have high nuclear β-catenin levels. The presence of reiterative and functionally important β-catenin asymmetries in two distantly related animal phyla suggests an ancient metazoan origin of a β-catenin-mediated binary cell-fate specification module.