Synthetic reconstitution of planar polarity initiation reveals principles of symmetry breaking across scales.

Collective migration acts as the symmetry-breaking cue that initiates planar cell polarity across tissue scales in engineered epithelial cells.

• Why it matters: Understanding how tissues break symmetry to start PCP is crucial for revealing mechanisms of tissue morphogenesis and organization, yet this process remains largely unknown.
• What they did: Researchers reconstituted polarity initiation ex vivo with engineered epithelial cells, demonstrating that collective migration induces front-back enrichment of CELSR junctions and aligns multicellular polarity, with CELSR acting independently of VANGL-FZD interactions.
• The result: Findings show that morphogenetic events like collective migration serve as triggers for spatial pattern emergence, revealing principles of symmetry breaking across molecular, cellular, and tissue levels.