Zyxin contributes to coupling between cell junctions and contractile actomyosin networks during apical constriction

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Apical constriction is a fundamental cell shape change driving morphogenesis across animal development.
• Actomyosin network contractions are crucial for apical constriction, but the precise triggers and regulatory mechanisms remain unclear.
• Existing evidence suggests mechanical links between actomyosin and cell junctions, rather than actomyosin contraction alone, may initiate apical constriction.

Purpose of the Study:

• To identify genes regulating the dynamic linkage between actomyosin networks and cell junctions during C. elegans gastrulation.
• To investigate the role of candidate linker proteins, such as AFD-1/afadin and ZYX-1/zyxin, in this process.
• To understand how developmental patterning spatiotemporally regulates cell shape changes.

Main Methods:

• Utilized C. elegans gastrulation as a model system.
• Employed proteomic and transcriptomic approaches to identify candidate genes.
• Developed a semi-automated image analysis tool to quantify cell junction movement.
• Investigated the localization and function of α-catenin, β-catenin, AFD-1/afadin, and ZYX-1/zyxin.

Main Results:

• α-catenin and β-catenin did not move centripetally with actomyosin networks, indicating linkage regulation occurs at the cadherin-catenin complex level.
• ZYX-1/zyxin was identified as a key linker protein contributing to cell-cell junction movement.
• Transcriptional upregulation of ZYX-1/zyxin was observed in cells undergoing apical constriction.
• ZYX-1/zyxin facilitates the inward pulling of cell-cell junctions by actomyosin networks.

Conclusions:

• ZYX-1/zyxin is essential for effective apical constriction by linking actomyosin contractions to cell junctions.
• The study identified novel genes, including ZYX-1/zyxin, involved in C. elegans gastrulation.
• Spatiotemporal regulation of ZYX-1/zyxin expression highlights a mechanism for controlling cell shape changes during development.
• The role of zyxin in membrane-cytoskeleton linkage suggests conserved functions in apical constriction across species.