Macrophage podosomes assemble at the leading lamella by growth and fragmentation

Area of Science:

• Cell Biology
• Cytoskeleton Dynamics
• Cell Adhesion

Background:

• Podosomes are dynamic actin-rich adhesion structures found at the leading edge of cells like macrophages.
• Understanding podosome formation and regulation is crucial for comprehending cell migration and tissue remodeling.

Purpose of the Study:

• To investigate the mechanisms of podosome assembly and formation at the cell periphery.
• To determine the role of microtubules in podosome dynamics and polarized formation.

Main Methods:

• Quantitative four-dimensional microscopy was used to observe podosome assembly in cells expressing beta-actin-ECFP and L-fimbrin-EYFP.
• The effects of microtubule inhibitors (paclitaxel and demecolcine) on podosome turnover and formation were analyzed.

Main Results:

• Podosomes assemble de novo or via fission of precursor structures.
• A large podosome cluster precursor, containing actin, fimbrin, and integrin, was identified.
• Microtubule inhibitors disrupted podosome turnover and polarized formation but not actin turnover within podosomes.

Conclusions:

• Podosome assembly occurs through distinct de novo and fission pathways.
• Precursor podosome structures contribute to cell adhesion.
• Microtubules are critical for the polarized formation and dynamics of podosomes, influencing cell adhesion at the leading edge.