Cytoskeletal Regulation of Podosome-Focal Adhesion Balance in GM-CSF- and Flt3L-Derived Dendritic Cells.

Dendritic cells (DCs) are key antigen-presenting cells essential for the initiation of immune responses. Their migration is tightly regulated by adhesive structures, including podosomes and focal adhesions (FAs), allowing for interactions with the extracellular matrix (ECM) for coordinated cell movement. The organization and dynamics of these structures are controlled by actin and microtubule cytoskeletons; however, the mechanisms governing their balance in distinct DC subsets are not completely understood. In this study, we investigated cytoskeletal regulation of the interplay between podosomes and FAs in GM-CSF-derived inflammatory-like DCs (GM-BMDCs) and Flt3L-derived conventional DCs (FL-BMDCs). GM-BMDCs showed a higher capacity to form podosomes compared with FL-BMDCs, which exhibited fewer and less prominent structures. Actin depolymerization resulted in the complete loss of podosomes, whereas disruption of microtubules induced podosome reorganization and altered the structure of FAs. Importantly, cytoskeletal perturbation in both DC subsets led to podosome dissolution, highlighting the requirement of cytoskeletal integrity for their maintenance. Furthermore, actin integrity was essential for podosome-mediated ECM degradation and efficient migration of GM-BMDCs, while microtubules fine-tuned the balance between podosome and focal adhesion dynamics, thereby regulating DC motility.