The role of the actin cortex in maintaining cell shape

Area of Science:

• Cell Biology
• Biophysics
• Mechanobiology

Background:

• The plasma membrane and actin cortex are crucial for cellular responses to mechanical forces in vivo.
• The paired membrane-cortex structure influences cell shape and response to deformation.

Purpose of the Study:

• To investigate the deformation response of the HeLa cell membrane and actin cortex to localized forces.
• To characterize the time-dependent strain and morphological recovery of cells under mechanical stress.

Main Methods:

• Applying highly localized forces to HeLa cells.
• Direct visualization of deformation in the loading plane.
• Characterizing time-dependent strain and morphological recovery.

Main Results:

• Cells largely recovered their pre-deformed morphology within approximately 2 minutes, even under significant loading.
• Regions above large-volume nuclei exhibited softness with negligible impact on morphological recovery.
• Deformation resistance and recovery were primarily governed by the actin network and rho-kinase-mediated contractility.

Conclusions:

• The actin cortex plays a dominant role in cellular mechanical response and shape recovery.
• Rho-kinase-mediated contractility is a critical factor in regulating cell deformation resistance and recovery.
• Nuclear volume does not significantly impede the cell's ability to recover its shape after mechanical deformation.