Lineage‐specific evolution of cnidarian Wnt ligands. Issue 5 (14th August 2014)

• Record Type: Journal Article
• Authors: Hensel, Katrin; Lotan, Tamar; Sanders, Steve M.; Cartwright, Paulyn; Frank, Uri
• Is Part Of: Evolution & development. Volume 16:Issue 5(2014)
• Page Start: 259
• Page End: 269
• Publication Date: 2014-08-14
• Subjects: Evolution (Biology) -- Periodicals; Developmental biology -- Periodicals; 576.82
• DOI: 10.1111/ede.12089
• Languages: English
• ISSNs: 1520-541X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>SUMMARY</title> <sec id="ede12089-sec-0001" sec-type="section"> <p>We have studied the evolution of <italic>Wnt</italic> genes in cnidarians and the expression pattern of all <italic>Wnt</italic> ligands in the hydrozoan <italic>Hydractinia echinata</italic>. Current views favor a scenario in which 12 <italic>Wnt</italic> sub‐families were jointly inherited by cnidarians and bilaterians from their last common ancestor. Our phylogenetic analyses clustered all medusozoan genes in distinct, well‐supported clades, but many orthologous relationships between medusozoan <italic>Wnts</italic> and anthozoan and bilaterian <italic>Wnt</italic> genes were poorly supported. Only seven anthozoan genes, <italic>Wnt2</italic>, <italic>Wnt4</italic>, <italic>Wnt5</italic>, <italic>Wnt6</italic>, <italic>Wnt 10</italic>, <italic>Wnt11</italic>, and <italic>Wnt16</italic> were recovered with strong support with bilaterian genes and of those, only the <italic>Wnt2</italic>, <italic>Wnt5</italic>, <italic>Wnt11</italic>, <italic>and Wnt16</italic> clades also included medusozoan genes. Although medusozoan <italic>Wnt8</italic> genes clustered with anthozoan and bilaterian genes, this was not well supported. In situ hybridization studies revealed poor conservation of expression patterns of putative <italic>Wnt</italic> orthologs within Cnidaria. In polyps, only <italic>Wnt1</italic>, <italic>Wnt3</italic>, and <italic>Wnt7</italic> were expressed at the same position in the studied cnidarian models <italic>Hydra, Hydractinia</italic>, and <italic>Nematostella</italic>. Different expression patterns are consistent with divergent functions. Our data do not fully support previous assertions regarding <italic>Wnt</italic> gene homology, and suggest a more complex history of <italic>Wnt</italic> family genes than previously suggested. This includes high rates of sequence divergence and lineage‐specific duplications of <italic>Wnt</italic> genes within medusozoans, followed by functional divergence over evolutionary time scales.</p> </sec> </abstract>