Molecular signature of an ancient organizer regulated by Wnt/\u03b2-catenin signalling during primary body axis patterning in Hydra

Puli Chandramouli Reddy,Suyog Ubhe,Saurabh J Pradhan,Sanjeev Galande,Amol Kolte,Akhila Gungi

doi:10.1038/s42003-019-0680-3

Puli Chandramouli Reddy, Suyog Ubhe + Show 4 more

Open Access

https://doi.org/10.1038/s42003-019-0680-3

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Abstract

Wnt/β-catenin signalling has been shown to play a critical role during head organizer formation in Hydra. Here, we characterized the Wnt signalling regulatory network involved in formation of the head organizer. We found that Wnt signalling regulates genes that are important in tissue morphogenesis. We identified that majority of transcription factors (TFs) regulated by Wnt/β-catenin signalling belong to the homeodomain and forkhead families. Silencing of Margin, one of the Wnt regulated homeodomain TFs, results in loss of the ectopic tentacle phenotype typically seen upon activation of Wnt signalling. Furthermore, we show that the Margin promoter is directly bound and regulated by β-catenin. Ectopic expression of Margin in zebrafish embryos results in body axis abnormalities suggesting that Margin plays a role in axis patterning. Our findings suggest that homeobox TFs came under the regulatory umbrella of Wnt/β-catenin signalling presumably resulting in the evolution of primary body axis in animal phyla.

Highlights

Wnt/β-catenin signalling has been shown to play a critical role during head organizer formation in Hydra
It has been reported that expansion of Wnt ligands took place before the Cnidaria–Bilateria split resulting in 11 Wnts in Hydra
We have demonstrated the conserved role of selected transcription factors in early embryonic axis patterning in vertebrates using the zebrafish model system

Summary

Introduction

Wnt/β-catenin signalling has been shown to play a critical role during head organizer formation in Hydra. Differential expression analysis of Wnt activated polyps using the custom hybrid transcriptome assembly demonstrated that 5261 transcripts are dysregulated (Fig. 1d, Supplementary Data 1). 88 unique TFs are differentially regulated by activation of Wnt signalling (Fig. 2a, Supplementary Data 2).

Results

Conclusion