Mechanical conditions preventing live cell extrusion during primary neurulation in amniotes

Area of Science:

• Developmental Biology
• Biophysics
• Cell Biology

Background:

• Primary neurulation forms the neural tube, a complex process requiring coordinated forces.
• Disruption of MARCKS protein leads to neural tube closure defects and apical cell extrusion.

Purpose of the Study:

• To investigate the mechanism of "live cell extrusion" in neural tube defects.
• To identify the mechanical factors causing cell extrusion during neurulation.

Main Methods:

• Utilized an energy-based vertex model of pseudostratified epithelia.
• Employed a continuum description of simplified epithelium.
• Analyzed the role of cell-cell and interfacial surface tensions.

Main Results:

• Demonstrated that cell extrusion occurs without apoptosis ("live cell extrusion").
• Showed that reduced apical/basal surface tension relative to cell-cell interfaces elicits extrusion.
• Derived a power law for epithelial stability based on cell density and surface tension.

Conclusions:

• Altered single-cell forces and polarization can cause tissue-scale instabilities during development.
• Mechanical instability, specifically related to surface tension, explains live cell extrusion.
• Findings provide insights into developmental defects and epithelial tissue mechanics.