Origin of Metazoan Cadherin Diversity and the Antiquity of the Classical Cadherin/Β-Catenin Complex
Origin of metazoan cadherin diversity and the antiquity of the classical cadherin/β-catenin complex Scott Anthony Nicholsa, Brock William Robertsb, Daniel Joseph Richterb, Stephen Robert Faircloughb, and Nicole Kingb,1 aDepartment of Biological Sciences, University of Denver, Denver, CO 80208; and bDepartment of Molecular and Cell Biology, University of California, Berkeley, CA 94720 Edited by Masatoshi Takeichi, RIKEN, Kobe, Japan, and approved June 20, 2012 (received for review December 19, 2011) The evolution of cadherins, which are essential for metazoan multi- flamingo, dachsous, fat, and fat-like cadherins regulate planar cellularity and restricted to metazoans and their closest relatives, cell polarity in organisms as disparate as Drosophila and mouse has special relevance for understanding metazoan origins. To re- (20–22). Members of the protocadherin family have diverse construct the ancestry and evolution of cadherin gene families, we functions that include mechanosensation in stereocilia and reg- analyzed the genomes of the choanoflagellate Salpingoeca rosetta, ulation of nervous system development (23, 24). It is not known the unicellular outgroup of choanoflagellates and metazoans Cap- whether the bilaterian roles of these cadherin families had al- saspora owczarzaki, and a draft genome assembly from the homo- ready evolved in the last common ancestor of metazoans, and it scleromorph sponge Oscarella carmela. Our finding of a cadherin is not clear how these cadherin families themselves originated. gene in C. owczarzaki reveals that cadherins predate the diver- To date, only one cadherin family—the hedgling family—is gence of the C. owczarzaki, choanoflagellate, and metazoan line- inferred to have been present in the last common ancestor of ages.
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