During whole-body regeneration, a bisection injury can trigger two different types of regeneration. To understand the transcriptional regulation underlying this adaptive response we characterized transcript abundance and chromatin accessibility during oral and aboral regeneration in the cnidarian Hydra vulgaris. We found that the initial response to amputation at both wound sites is identical and includes widespread apoptosis and the activation of the oral-specifying Wnt signaling pathway. By 8 hours post-amputation, Wnt signaling became restricted to oral regeneration. Wnt pathway genes were also upregulated in puncture wounds and these wounds induced the formation of ectopic oral structures if pre-existing organizers were simultaneously amputated. Our work suggests that oral patterning is activated as part of a generic injury response in Hydra, and that alternative injury outcomes are dependent on signals from the surrounding tissue. Furthermore, Wnt signaling is likely part of a conserved wound response predating the split of cnidarians and bilaterians.
All code used in this study is available both as a git repository at github.com/cejuliano/jcazet_regeneration_patterning and on Dryad at doi.org/10.25338/B8S612. FASTQ files of raw ATAC-seq and RNA-seq reads, expression matrices for ATAC-seq and RNA-seq reads mapped to the Hydra 2.0 genome reference, consensus peak files, and bigwig genome tracks of individual and pooled ATAC-seq replicates are available through the Gene Expression Omnibus under the accession GSE152994. The Hydra 2.0 genome gene model IDs associated with the gene names used throughout this study are provided in Figure 1-Figure Supplement 8. Full differential gene expression results are available in Supplementary Files 1 and 2. Motif enrichment and variability results are available in Supplementary File 3.
Oral Regeneration Is the Default Pathway Triggered by Injury in HydraNCBI Gene Expression Omnibus, GSE152994.
Oral Regeneration Is the Default Pathway Triggered by Injury in HydraDryad Digital Repository, 10.25338/B8S612.
Stem cell differentiation trajectories in Hydra resolved at single cell resolutionNCBI Gene Expression Omnibus, GSE121617.
Generic and context-dependent gene modulations during Hydra whole body regenerationNCBI Gene Expression Omnibus, GSE111534.
- Celina Juliano
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Tatjana Piotrowski, Stowers Institute for Medical Research, United States
© 2021, Cazet et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.