Dynamic transposable element expression during Hydra head regeneration

Transposable elements (TEs) contribute to genome expansions, gene duplications, and the evolution of gene regulatory networks. Recent work has highlighted the role of TE domestication in contributing to regulatory programs during animal development. Likewise, a role for TEs in regeneration has been proposed but remains understudied. Hydra vulgaris is a cnidarian polyp with astonishing regenerative ability. Approximately 60% of the Hydra genome is made up of transposable elements with a recent LINE/CR1 expansion potentially contributing to their speciation. Previous studies identified signatures of TE expression during Hydra regeneration, but the specific TEs involved, and their temporal expression patterns remain unknown. Here, I used publicly available RNA-sequencing data from a time course of Hydra head regeneration to characterize TE expression patterns. 262 TEs with dynamic temporal expression over regeneration were identified. This analysis also revealed TEs with expression patterns similar to genes involved in wound repair and tissue repatterning. Some dynamically expressed TEs were in close genomic proximity to genes involved in apoptosis, extracellular matrix remodeling, and proteins that interact with regeneration signaling pathways. This study provides a set of candidate TEs for future investigation into the mechanistic role of TEs in regeneration.