A wound-induced Wnt expression program controls planarian regeneration polarity

Area of Science:

• Developmental Biology
• Regenerative Biology
• Planarian Biology

Background:

• Tissue regeneration requires specifying new tissue identity.
• The role of wound signaling in repatterning regenerating tissues remains unclear.
• Planarian head-tail regeneration polarity, dependent on Wnt signaling, serves as a model for studying tissue identity.

Purpose of the Study:

• To investigate the role of wound signaling in planarian regeneration polarity.
• To determine if wound signals provide input into tissue repatterning during regeneration.
• To elucidate the function of Smed-wntP-1 and Smed-wntP-2 in establishing regeneration polarity.

Main Methods:

• Analyzing gene expression patterns (Smed-wntP-1, Smed-wntP-2) after wounding in planarians.
• Inhibiting Smed-wntP-1 and Smed-wntP-2 to observe effects on regeneration polarity.
• Performing experiments with and without neoblast stem cells to assess gene function independence.

Main Results:

• Smed-wntP-1 is rapidly and broadly induced by wounds, and its new expression is required for regeneration polarity.
• Smed-wntP-2 expression is induced subsequent to Smed-wntP-1 and localized to posterior wounds.
• Wnt gene expression changes occur independently of neoblast stem cells, suggesting an instructive role in polarity.
• Inhibition of Smed-wntP-2 exacerbates polarity defects caused by Smed-wntP-1 inhibition.

Conclusions:

• Wound-induced signaling, specifically through Wnt pathway genes, plays a crucial role in specifying regeneration polarity.
• The Wnt signaling pathway acts instructively to reset body axis features during regeneration.
• This wound-induced input is independent of neoblast stem cells, suggesting a direct role in pattern formation.