Dynamic Polarization of the Multiciliated Planarian Epidermis between Body Plan Landmarks

Area of Science:

• Developmental Biology
• Cell Biology
• Regenerative Medicine

Background:

• Polarity is a fundamental biological principle, crucial for organizing cells and tissues.
• Understanding how global body plan polarity influences local cell polarity is a key challenge in developmental biology.
• Planarian flatworms offer a unique model for studying polarity due to their remarkable regenerative capabilities and anatomical plasticity.

Purpose of the Study:

• To investigate the interplay between global body plan polarity and local cell polarity in planarian flatworms.
• To elucidate the molecular mechanisms coordinating polarity across different organizational scales.
• To establish a framework for understanding how cellular polarity aligns with body plan landmarks.

Main Methods:

• Quantitative analysis of ciliary rootlet orientation in planarian epidermis.
• Mathematical modeling to rationalize observed polarity fields and responses to experimental manipulations.
• Investigation of core Planar Cell Polarity (PCP) and Frizzled/Dishevelled (Ft/Ds) signaling pathways.

Main Results:

• A dynamic polarity field was identified, with distinct head and tail determinants for anteroposterior (A/P) polarization.
• Body margin acts as a determinant for mediolateral (M/L) polarization.
• Mathematical models supported the superposition of independent A/P and M/L polarity fields.
• Core PCP and Ft/Ds pathways were identified as molecular mediators of these polarity fields.

Conclusions:

• A framework for aligning cellular polarity vectors with planarian body plan landmarks was established.
• The core PCP and Ft/Ds pathways function as evolutionarily conserved modules for 2D tissue polarization.
• This study provides insights into the fundamental principles of biological organization and regeneration.