title: Evolutionary conservation of the eumetazoan gene regulatory landscape.
abstract: Despite considerable differences in morphology and complexity of body plans among animals, a great part of the gene set is shared among Bilateria and their basally branching sister group, the Cnidaria. This suggests that the common ancestor of eumetazoans already had a highly complex gene repertoire. At present it is therefore unclear how morphological diversification is encoded in the genome. Here we address the possibility that differences in gene regulation could contribute to the large morphological divergence between cnidarians and bilaterians. To this end, we generated the first genome-wide map of gene regulatory elements in a nonbilaterian animal, the sea anemone Nematostella vectensis. Using chromatin immunoprecipitation followed by deep sequencing of five chromatin modifications and a transcriptional cofactor, we identified over 5000 enhancers in the Nematostella genome and could validate 75% of the tested enhancers in vivo. We found that in Nematostella, but not in yeast, enhancers are characterized by the same combination of histone modifications as in bilaterians, and these enhancers preferentially target developmental regulatory genes. Surprisingly, the distribution and abundance of gene regulatory elements relative to these genes are shared between Nematostella and bilaterian model organisms. Our results suggest that complex gene regulation originated at least 600 million yr ago, predating the common ancestor of eumetazoans.
authors.affiliation: Department of Molecular Evolution and Development, Center for Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria.
authors.forename: Michaela
authors.initials: M
authors.lastname: Schwaiger
authors.forename: Anna
authors.initials: A
authors.lastname: Schönauer
authors.forename: André F
authors.initials: AF
authors.lastname: Rendeiro
authors.forename: Carina
authors.initials: C
authors.lastname: Pribitzer
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schauer
authors.forename: Anna F
authors.initials: AF
authors.lastname: Gilles
authors.forename: Johannes B
authors.initials: JB
authors.lastname: Schinko
authors.forename: Eduard
authors.initials: E
authors.lastname: Renfer
authors.forename: David
authors.initials: D
authors.lastname: Fredman
authors.forename: Ulrich
authors.initials: U
authors.lastname: Technau
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004742:Enhancer Elements, Genetic; D019143:Evolution, Molecular; D005786:Gene Expression Regulation / Q000235:genetics*; D053263:Gene Regulatory Networks / Q000235:genetics*; D016678:Genome; D010802:Phylogeny; D012615:Sea Anemones