Ancient animal microRNAs and the evolution of tissue identity

Item Type:	Article
Title:	Ancient animal microRNAs and the evolution of tissue identity
Creators Name:	Christodoulou, F. and Raible, F. and Tomer, R. and Simakov, O. and Trachana, K. and Klaus, S. and Snyman, H. and Hannon, G.J. and Bork, P. and Arendt, D.
Abstract:	The spectacular escalation in complexity in early bilaterian evolution correlates with a strong increase in the number of microRNAs. To explore the link between the birth of ancient microRNAs and body plan evolution, we set out to determine the ancient sites of activity of conserved bilaterian microRNA families in a comparative approach. We reason that any specific localization shared between protostomes and deuterostomes (the two major superphyla of bilaterian animals) should probably reflect an ancient specificity of that microRNA in their last common ancestor. Here, we investigate the expression of conserved bilaterian microRNAs in Platynereis dumerilii, a protostome retaining ancestral bilaterian features, in Capitella, another marine annelid, in the sea urchin Strongylocentrotus, a deuterostome, and in sea anemone Nematostella, representing an outgroup to the bilaterians. Our comparative data indicate that the oldest known animal microRNA, miR-100, and the related miR-125 and let-7 were initially active in neurosecretory cells located around the mouth. Other sets of ancient microRNAs were first present in locomotor ciliated cells, specific brain centres, or, more broadly, one of four major organ systems: central nervous system, sensory tissue, musculature and gut. These findings reveal that microRNA evolution and the establishment of tissue identities were closely coupled in bilaterian evolution. Also, they outline a minimum set of cell types and tissues that existed in the protostome-deuterostome ancestor.
Keywords:	Brain, Cilia, Conserved Sequence, Digestive System, Evolution, In Situ Hybridization, MicroRNAs, Molecular Sequence Data, Organ Specificity, Phylogeny, Polychaeta, Sea Anemones, Sea Urchins, Animals, Annelida
Source:	Nature
ISSN:	0028-0836
Publisher:	Nature Publishing Group
Volume:	463
Number:	7284
Page Range:	1084-1088
Date:	25 February 2010
Official Publication:	https://doi.org/10.1038/nature08744
PubMed:	View item in PubMed

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