A Comprehensive Transcriptomic and Proteomic Analysis of Hydra Head Regeneration

Area of Science:

• * Molecular Biology
• * Developmental Biology
• * Regenerative Medicine

Background:

• * The freshwater polyp *Hydra* sp. possesses exceptional regenerative abilities.
• * Understanding *Hydra*'s regeneration mechanisms can offer insights into stem cell biology and tissue repair.

Purpose of the Study:

• * To investigate the molecular mechanisms underlying stem cell-based regeneration in *Hydra* polyps.
• * To identify key genes and signaling pathways involved in *Hydra* head regeneration.

Main Methods:

• * Integrative transcriptomic and proteomic/phosphoproteomic analysis.
• * Stable isotope labeling by amino acids in cell culture (SILAC).

Main Results:

• * Identified two distinct molecular cascades: early injury response and later signaling-driven patterning.
• * Discovered protein stabilization and transcript upregulation in the early injury phase, followed by Wnt and TGF-beta signaling activation.
• * Observed moderate overlap between proteomic and transcriptomic responses, suggesting decoupled transcriptional and translational regulation.
• * Found no major role for interstitial stem cells or their derivatives in head regeneration.
• * Noted enrichment of recent genes in early regeneration and conserved genes in later stages, with transposon insertions in early-response genes.

Conclusions:

• * *Hydra* regeneration is orchestrated by distinct early and late molecular phases.
• * Decoupled transcriptional and translational regulation plays a role in the regenerative process.
• * Genetic dynamicity, including recent genes and transposon activity, is crucial for *Hydra*'s regeneration.
• * Interstitial stem cells are not the primary drivers of *Hydra* head regeneration.