An ancestral Wnt-Brachyury feedback loop in axial patterning and recruitment of mesoderm-determining target genes.

Nature ecology & evolution 2022 Dec

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Transcription factors are crucial drivers of cellular differentiation during animal development and often share ancient evolutionary origins. The T-box transcription factor Brachyury plays a pivotal role as an early mesoderm determinant and neural repressor in vertebrates; yet, the ancestral function and key evolutionary transitions of the role of this transcription factor remain obscure. Here, we present a genome-wide target-gene screen using chromatin immunoprecipitation sequencing in the sea anemone Nematostella vectensis, an early branching non-bilaterian, and the sea urchin Strongylocentrotus purpuratus, a representative of the sister lineage of chordates. Our analysis reveals an ancestral gene regulatory feedback loop connecting Brachyury, FoxA and canonical Wnt signalling involved in axial patterning that predates the cnidarian-bilaterian split about 700 million years ago. Surprisingly, we also found that part of the gene regulatory network controlling the fate of neuromesodermal progenitors in vertebrates was already present in the common ancestor of cnidarians and bilaterians. However, while several endodermal and neuronal Brachyury target genes are ancestrally shared, hardly any of the key mesodermal downstream targets in vertebrates are found in the sea anemone or the sea urchin. Our study suggests that a limited number of target genes involved in mesoderm formation were newly acquired in the vertebrate lineage, leading to a dramatic shift in the function of this ancestral developmental regulator. © 2022. The Author(s), under exclusive licence to Springer Nature Limited.

Citation

Michaela Schwaiger, Carmen Andrikou, Rohit Dnyansagar, Patricio Ferrer Murguia, Periklis Paganos, Danila Voronov, Bob Zimmermann, Tatiana Lebedeva, Heiko A Schmidt, Grigory Genikhovich, Giovanna Benvenuto, Maria Ina Arnone, Ulrich Technau. An ancestral Wnt-Brachyury feedback loop in axial patterning and recruitment of mesoderm-determining target genes. Nature ecology & evolution. 2022 Dec;6(12):1921-1939