Meeting Abstract

P2-66  Friday, Jan. 6 15:30 – 17:30  Secreted frizzled related protein is a putative downstream target of PaxB in the freshwater sponge, Ephydatia muelleri HALL, C*; RODRIGUEZ, M; WEI, A; WICTOR, E; GAZI, A; GARCIA, J; GENTILE, G; RIVERA, A; HILL, A; Univ. of Richmond, Richmond; Univ. of Richmond, Richmond; Univ. of Pacific, Stockton; Univ. of Pacific, Stockton; Univ. of Richmond, Richmond; Univ. of Richmond, Richmond; Univ. of Richmond, Richmond; Univ. of Pacific, Stockton; Univ. of Richmond, Richmond ahill2@richmond.edu http://biology.richmond.edu/research/research-labs/april-hill-lab.html

The Wnt Signaling pathway and the Pax/Six gene network both play important roles in establishing the sponge body plan and aquiferous system. Using computational approaches to identify transcription factor binding motifs in sponge genomes, we located putative PaxB binding sites upstream of a Secreted Frizzled Related Protein (SFRP) gene in Ephydatia muelleri. The EmSFRP contains a Frizzled domain with predicted glycosylation site as well as a Netrin domain. EmSFRP is expressed throughout development, but with highest levels in juvenile sponges. Knockdown of EmPaxB expression by RNAi results in decreased expression of EmSFRP, supporting that PaxB directly or indirectly regulates SFRP in sponges. Interestingly, knockdown of EmSFRP using dsRNA leads to ectopic oscula formation during development, as has been reported when GSK3 is inhibited by LiCl in this species. This data supports a hypothesis that EmSFRP may act as an antagonist of Wnt signaling in E. muelleri and that the regulation of the Wnt pathway by the Pax/Six network may have been established before sponges diverged from the rest of the metazoans.