Mechanics of spreading cells probed by atomic force microscopy

Area of Science:

• Cell biology
• Biophysics
• Mechanobiology

Background:

• Cellular adhesion and motility are crucial for tissue homeostasis and morphogenesis.
• Cells require membrane deformability and reservoirs to manage morphological changes during adhesion and spreading.
• Alterations in cellular mechanics during cell spreading are not well understood.

Purpose of the Study:

• To investigate changes in cortical and plasma membrane mechanics during cell adhesion and spreading.
• To characterize the relationship between membrane tension, area, and cell morphology.
• To understand how cells regulate membrane area to cope with mechanical stress.

Main Methods:

• Atomic force microscopy to measure cortical and plasma membrane mechanics.
• Force measurements over time to monitor spreading progress.
• Fluorescence microscopy to visualize plasma membrane structure.

Main Results:

• Significant changes in cortical tension, membrane tension, and membrane area occur during initial cell adhesion.
• Cortical and membrane tension stabilize at the expense of excess membrane area as cells spread.
• Cell spreading is initiated by a transient tension drop, compensated by reduced membrane area.
• Inhibiting cytoskeletal integrity, membrane tension, or excess surface area perturbs cell spreading.

Conclusions:

• Single cells dynamically adjust their membrane area in response to changes in membrane tension.
• Excess membrane reservoirs, like invaginations, facilitate membrane supply during adhesion.
• Cell spreading involves a coordinated regulation of mechanical properties and membrane dynamics.