New genomic data and analyses challenge the traditional vision of animal epithelium evolution

Belahbib Hassiba, Renard Emmanuelle, Santini Sébastien, Jourda Cyril, Claverie Jean-Michel, Borchiellini Carole, Le Bivic André. 2018. New genomic data and analyses challenge the traditional vision of animal epithelium evolution. BMC Genomics, 19:393, 15 p.

https://doi.org/10.1186/s12864-018-4715-9

Article de revue ; Article de recherche ; Article de revue à facteur d'impact Revue en libre accès total

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Quartile : Q2, Sujet : BIOTECHNOLOGY & APPLIED MICROBIOLOGY / Quartile : Q2, Sujet : GENETICS & HEREDITY

Résumé : Background: The emergence of epithelia was the foundation of metazoan expansion. Epithelial tissues are a hallmark of metazoans deeply rooted in the evolution of their complex developmental morphogenesis processes. However, studies on the epithelial features of non-bilaterians are still sparse and it remains unclear whether the last common metazoan ancestor possessed a fully functional epithelial toolkit or if it was acquired later during metazoan evolution. Results: To investigate the early evolution of animal epithelia, we sequenced the genome and transcriptomes of two new sponge species to characterize epithelial markers such as the E-cadherin complex and the polarity complexes for all classes (Calcarea, Demospongiae, Hexactinellida, Homoscleromorpha) of sponges (phylum Porifera) and compare them with their homologues in Placozoa and in Ctenophora. We found that Placozoa and most sponges possess orthologues of all essential genes encoding proteins characteristic of bilaterian epithelial cells, as well as their conserved interaction domains. In stark contrast, we found that ctenophores lack several major polarity complex components such as the Crumbs complex and Scribble. Furthermore, the E-cadherin ctenophore orthologue exhibits a divergent cytoplasmic domain making it unlikely to interact with its canonical cytoplasmic partners. Conclusions: These unexpected findings challenge the current evolutionary paradigm on the emergence of epithelia. Altogether, our results raise doubt on the homology of protein complexes and structures involved in cell polarity and adhesive-type junctions between Ctenophora and Bilateria epithelia.

Mots-clés libres : Epithelium evolution, Non-bilaterian animals, Cell polarity, Cell-cell junctions

Classification Agris : L10 - Génétique et amélioration des animaux
L52 - Physiologie animale - Croissance et développement

Champ stratégique Cirad : Hors axes (2014-2018)

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