Meeting Abstract

99.5  Monday, Jan. 6 14:30  Temporal and spatial expression of the Frizzled gene family in a spiral-cleaving embryo BASTIN, B.R.*; CHOU, H.; PRUITT, M.M.; SCHNEIDER, S.Q.; Iowa State University; Iowa State University; Iowa State University; Iowa State University brbastin@iastate.edu

Wnt signal transduction pathways are highly conserved in most metazoans and involved in many developmental processes from cell fate specification to axis formation. Proteins with Frizzled cysteine rich domains play key roles within these pathways: Frizzleds as Wnt ligand receptors transmitting signaling events and Secreted Frizzled Related Proteins (SFRPs) as Wnt signal modulators. Comparative genomic analysis revealed that four distinct frizzled receptor genes and two SFRP genes were present in the last common bilaterian ancestor. Currently, little is known about the complement and roles of the Frizzled gene family in spiralians, a large group of animal phyla including mollusks and annelids. We made use of embryos of the marine annelid Platynereis dumerilii whose cell lineage has been described, and where canonical wnt/beta-catenin signaling was previously implicated to distinguish between sister cell fates throughout early development. We found that the genome of P. dumerilii retained copies of the four Frizzled and two SFRP ancestral genes as well as an additional Frizzled-related gene. Here we utilize stage specific RNA-seq and in situ hybridization to define the temporal and spatial expression of each of these genes during early development. Those expressed early exhibit either a polarized expression along the animal-vegetal axis or cell lineage specific expression. As has also been found in cnidarians and echinoderms, Frizzled1/2/7 transcripts are most prominent and maternally provided. This is the first comprehensive analysis of Frizzled and Frizzled related genes in a spiral-cleaving embryo, and a first glimpse at how these potent developmental regulators may influence patterning in spiralians.