The epidermal differentiation complex (EDC) is a cluster of genes encoding components of the skin barrier in terrestrial vertebrates. The human EDC is comprised of S100A genes, S100 Fused-Type Protein (SFTP) genes such as filaggrin, and Single-coding-exon EDC (SEDC) genes such as loricrin. The evolution of the EDC can be reconstructed by comparative analysis of genome sequences of phylogenetically diverse vertebrates. Here, we determined the presence and chromosmal arrangement of S100A, SFTP and SEDC genes in the latest releases of genome sequences from the main clades of amniotes (mammals, reptiles, birds), amphibians (frogs, salamanders, caecilians) and lungfish. S100A gene clusters were identified in all species investigated, and SFTP genes were found in amniotes and amphibians but not in fish. SEDC genes are present in high numbers (20-100) in mammals, reptiles and birds, whereas no SEDC genes exist in frogs, salamanders and lungfish. We show that 2-4 SEDCs are present in the EDC of caecilians (Amphibia: Gymnophiona). Comparative analysis of tissue transcriptomes indicated predominant expression of SEDC genes in the skin of caecilians. The proteins encoded by caecilian SEDC genes resemble human small proline-rich proteins and involucrin with regard to high contents of proline and potential sites of transglutamination, i.e. glutamine and lysine residues. The results of this study demonstrate that SEDC-type skin barrier genes are not restricted to amniotes and, therefore, appear to have originated during the evolutionary transition from fully aquatic to terrestrial life in a common ancestor of modern tetrapods.

LB031 - Comparative genomics suggests that the epidermal differentiation complex originated and diversified during the evolutionary transition from life in water to life on land

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.