JNK signalling is necessary for a Wnt- and stem cell-dependent regeneration programme

Area of Science:

• Developmental Biology
• Regenerative Medicine
• Molecular Biology

Background:

• Regeneration integrates new and old tissues in adult organisms.
• Conserved signaling pathways orchestrate both development and regeneration.
• The JNK signaling cascade's role in planarian regeneration requires further investigation.

Purpose of the Study:

• To investigate the role of the conserved JNK signaling cascade in planarian posterior regeneration.
• To understand how JNK signaling influences the establishment of posterior Wnt expression.
• To explore potential rescue mechanisms for regeneration defects caused by JNK pathway abrogation.

Main Methods:

• RNA interference (RNAi) to abrogate JNK signaling.
• Pharmacological inhibition of JNK signaling.
• Analysis of posterior and polarity marker expression.
• Assessment of stem cell-dependent Wnt expression.
• Overactivation of Hedgehog (Hh) and Wnt signaling pathways for rescue experiments.

Main Results:

• Abrogation of JNK signaling blocks planarian posterior regeneration and posterior marker expression.
• Early injury-induced polarity marker expression remains unaffected.
• The stem cell-dependent phase of posterior Wnt expression is not established upon JNK pathway disruption.
• Overactivation of Hh or Wnt signaling rescues the posterior regeneration defect by promoting Wnt activity.

Conclusions:

• JNK signaling is essential for establishing stem cell-dependent Wnt expression during planarian posterior regeneration.
• The interaction between JNK and Wnt signaling in posterior regeneration may be conserved across species, including vertebrates.
• This conserved interaction is proposed to be instructive for planarian posterior regeneration.