Dynamics of podosome stiffness revealed by atomic force microscopy

Area of Science:

• Cell Biology
• Biophysics
• Biomaterials Science

Background:

• Podosomes are actin-rich cellular structures essential for macrophage functions like matrix interaction and degradation.
• Understanding podosome biophysics is key to elucidating their role in cell migration and tissue remodeling.

Purpose of the Study:

• To investigate the physical properties and dynamic behavior of podosomes in living macrophages.
• To explore the relationship between podosome structure, mechanical properties, and F-actin/myosin II activity.

Main Methods:

• Utilized soft lithography, atomic force microscopy (AFM), and correlative fluorescence microscopy.
• Micropatterned fibrinogen substrates were used to confine podosome formation for AFM analysis.
• Measured podosome height and stiffness in living human macrophages.

Main Results:

• Podosome height was measured at 578 ± 209 nm and stiffness at 43.8 ± 9.3 kPa.
• Podosome physical properties were independent of the underlying matrix composition.
• Time-lapse AFM demonstrated periodic stiffness variations linked to F-actin and myosin II activity.

Conclusions:

• Atomic force microscopy enables nanoscale characterization of podosome biophysical properties in living cells.
• Podosome dynamics involve complex stiffness variations regulated by cytoskeletal components.
• This AFM-based approach provides new avenues for studying podosome mechanics in health and disease.