Contribution of cellular contractility to spatial and temporal variations in cellular stiffness

Area of Science:

• Cellular mechanics
• Biophysics
• Cytoskeletal dynamics

Background:

• Cellular stiffness is crucial for cell function.
• The actin cytoskeleton, particularly stress fibers, is known to contribute to cell mechanics.

Purpose of the Study:

• To investigate the relationship between cellular contractility and stiffness.
• To determine the role of the actin cytoskeleton in modulating cell mechanical properties.

Main Methods:

• Scanning probe microscopy to measure cellular stiffness.
• Immunofluorescence microscopy to observe actin stress fibers, myosin II, and vinculin.
• Pharmacological manipulation of cellular contractility using lysophosphatidic acid and Y-27632.

Main Results:

• Cellular stiffness directly correlates with cellular contractility; increased contractility leads to stiffening, while decreased contractility leads to softening.
• Variations in stiffness were observed in both stress fibers and the entire cell.
• Changes in cellular stiffness were primarily attributed to rearrangements of the actin network, particularly on the dorsal cell surface, involving myosin II and vinculin.

Conclusions:

• The actin cytoskeletal network and its contractility are key determinants of mechanical stability in adherent cells.
• Dynamic rearrangements within the actin network underlie the modulation of cellular stiffness.