title: Landscape of histone modifications in a sponge reveals the origin of animalcis-regulatory complexity.
abstract: Combinatorial patterns of histone modifications regulate developmental and cell type-specific gene expression and underpin animal complexity, but it is unclearwhenthis regulatory system evolved. By analysing histone modifications in a morphologically-simple, early branching animal, the spongeAmphimedonqueenslandica, we show that the regulatory landscape used by complex bilaterians was already in place at the dawn of animal multicellularity. This includes distal enhancers, repressive chromatin and transcriptional units marked by H3K4me3 that vary with levels of developmental regulation. Strikingly,Amphimedonenhancers are enriched in metazoan-specific microsyntenic units, suggesting that their genomic location is extremely ancient and likely to place constraints on the evolution of surrounding genes. These results suggest that the regulatory foundation for spatiotemporal gene expression evolved prior to the divergence of sponges and eumetazoans, and was necessary for the evolution of animal multicellularity.
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Federico
authors.identifier: http://orcid.org/0000-0001-5111-8816
authors.initials: F
authors.lastname: Gaiti
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Katia
authors.initials: K
authors.lastname: Jindrich
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Selene L
authors.initials: SL
authors.lastname: Fernandez-Valverde
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Kathrein E
authors.initials: KE
authors.lastname: Roper
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Degnan
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, Australia.
authors.forename: Miloš
authors.identifier: http://orcid.org/0000-0002-7564-0868
authors.initials: M
authors.lastname: Tanurdžić
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005786:Gene Expression Regulation; D042421:Histone Code; D011161:Porifera / Q000235:genetics*
keywords: A. queenslandica; cis-regulation; developmental biology; enhancers; evolution of multicellularity; evolutionary biology; gene expression; genomics; histone modifications; stem cells