Meeting Abstract
37.2 Sunday, Jan. 5 08:15 The ins and outs of beta-catenin mediated binary cell fate specification SCHNEIDER, SQ*; BASTIN, BR; PRUITT, MM; LETCHER, EJ; CHOU, H; Iowa State University; Iowa State University; Iowa State University; Iowa State University; Iowa State University sqs@iastate.edu
In the spiralian annelid Platynereis dumerilii each embryonic cell division oriented along the animal-vegetal axis is accompanied by higher nuclear accumulation of beta-catenin in the vegetal-pole daughter cell. As in the distantly related C. elegans where the Wnt/beta-catenin pathway is activated after every anterior-posterior oriented cell division, these observed reiterative asymmetries appear to convey lineage specific cell fate decisions. Ectopic activation of beta-catenin in animal-pole daughters causes the animal-pole daughter cell to adopt the fate of its vegetal-pole daughter cell. However, in contrast to the highly derived Wnt/beta-catenin activation mechanism in C.elegans, individual components of the Wnt/beta-catenin signal transduction pathways are highly conserved in Platynereis. To gain insights into mechanism and contribution of reiterative beta-catenin asymmetries to segregate cell fates in a spiral cleaving embryo and the formation of the annelid body plan, we (1) defined the stereotyped sister cell asymmetries (as observed by different cell sizes, cell cycle times, and beta-catenin activation patterns) in each cell division cycle until the 220 cell stage, (2) deployed a variety of RNA-seq based approaches to identify genes that comprise the reiterative Wnt/beta-catenin activation mechanisms and potential downstream targets in normal and compromised embryos, and (3) mapped the expression of Wnt pathway components (ligands, receptors, intracellular components, potential target genes) into distinct cell lineages. Our analysis provides the first comprehensive view of spatial and temporal inputs and outputs of Wnt signaling into embryos utilizing a spiral-mode of cell divisions to segregate cell fates.
