Meeting Abstract

S5.4  Monday, Jan. 5  The ancestry of animal cell signaling genes NICHOLS, Scott A.; University of California, Berkeley nichols1@berkeley.edu

The evolution of cell signaling mechanisms is thought to have been a pre-requisite to the evolution of multicellularity and the diversification of animal body plans. Reconstructing the ancestry of these mechanisms is complicated by their complexity and by the functional diversity of their molecular components. With more than 20 known binding partners, beta-catenin is a prototype of a multifunctional signaling molecule. Among other functions, beta-catenin plays critical roles in canonical Wnt signaling and cadherin-mediated cell adhesion. By exploiting the phylogenetic position of sponges, I have employed comparative and functional genomic approaches to explore the ancestry of beta-catenin function in animals. Specifically, the comparative analysis of beta-catenin orthologs in sponges, placozoans, cnidarians, and bilaterians suggests that structural aspects of beta-catenin are more highly conserved than functionally important amino acid motifs in the unstructured N- and C-terminal regions. Nevertheless, this comparative sequence analysis suggests that the signaling and adhesive functions of beta-catenin (at least) evolved prior to the radiation of modern animals. To test this prediction I have employed a yeast two-hybrid screen to identify candidate binding partners of beta-catenin in the sponge Oscarella carmela. Here, I discuss the outcomes of this analysis and use in situ hybridization and immunohistochemical techniques to further explore the timing of expression and subcellular localization of beta-catenin and key binding partners throughout sponge development.