Polychaetoid/ZO-1 strengthens cell junctions under tension while localizing differently than core adherens junction...

Area of Science:

• Cell Biology
• Developmental Biology
• Biophysics

Background:

• Embryonic development involves significant cell shape changes and movements, requiring dynamic linkages between cell-cell junctions and the actomyosin cytoskeleton.
• This linkage is mediated by mechanosensitive multiprotein complexes, but the precise mechanisms and roles of individual proteins are still being elucidated.

Approach:

• Combined genetic, cell biological, and modeling approaches to study the function of *Drosophila* Polychaetoid (Pyd), the homolog of mammalian ZO-1.
• Utilized structured illumination microscopy to visualize the molecular architecture of cell-cell junctions during dynamic cellular events.

Key Points:

• Polychaetoid (Pyd) reinforces cell junctions under tension and is essential for facilitating cell rearrangements during embryonic development.
• Pyd is critical for maintaining junctional contractility, as its absence leads to stalled cell rearrangements.
• Structured illumination microscopy revealed distinct localization patterns: cadherin-catenin and Cno are enriched in puncta, while Pyd localizes to strands extending from core junctional proteins.

Conclusions:

• Pyd plays a crucial role in reinforcing cell-cell junctions and enabling dynamic cell movements necessary for shaping the embryonic body plan.
• The findings suggest a complex protein network at the junction-cytoskeletal interface, where different proteins exhibit distinct localizations and functions to establish robust cellular connections.