title: Structural molecular components of septate junctions in cnidarians point to the origin of epithelial junctions in eukaryotes.
abstract: Septate junctions (SJs) insure barrier properties and control paracellular diffusion of solutes across epithelia in invertebrates. However, the origin and evolution of their molecular constituents in Metazoa have not been firmly established. Here, we investigated the genomes of early branching metazoan representatives to reconstruct the phylogeny of the molecular components of SJs. Although Claudins and SJ cytoplasmic adaptor components appeared successively throughout metazoan evolution, the structural components of SJs arose at the time of Placozoa/Cnidaria/Bilateria radiation. We also show that in the scleractinian coral Stylophora pistillata, the structural SJ component Neurexin IV colocalizes with the cortical actin network at the apical border of the cells, at the place of SJs. We propose a model for SJ components in Cnidaria. Moreover, our study reveals an unanticipated diversity of SJ structural component variants in cnidarians. This diversity correlates with gene-specific expression in calcifying and noncalcifying tissues, suggesting specific paracellular pathways across the cell layers of these diploblastic animals.
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco pganot@centrescientifique.mc.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ganot
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco.
authors.forename: Didier
authors.initials: D
authors.lastname: Zoccola
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco.
authors.forename: Eric
authors.initials: E
authors.lastname: Tambutté
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Voolstra
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
authors.forename: Manuel
authors.initials: M
authors.lastname: Aranda
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco.
authors.forename: Denis
authors.initials: D
authors.lastname: Allemand
authors.affiliation: Marine Biology Department, Centre Scientifique de Monaco, Quai Antoine Premier, Monaco.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Tambutté
mesh_terms: D000818:Animals; D003063:Cnidaria / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology / Q000379:methods; D004847:Epithelial Cells / Q000502:physiology*; D056890:Eukaryota / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D016678:Genome; D007365:Intercellular Junctions / Q000235:genetics / Q000378:metabolism*; D008957:Models, Genetic; D010802:Phylogeny; D062725:Tight Junction Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D062725:Tight Junction Proteins
keywords: Capsaspora; Claudin; Contactin; Coracle; DSCAM; Epitheliozoa; MAGUK; Monosiga; Na+/K+ ATPase transporter; Nbl4; Neurexin; Neuroglian; corals; ctenophores; para-cellular pathway; permselectivity; poriferans