Dendritic cells (DCs) are specialized antigen-presenting cells (APCs) that play a central role in the initiation of immune responses. Immature DCs exhibit a slow, mesenchymal mode of migration, enabling efficient tissue surveillance and antigen uptake. Upon activation, they undergo maturation and switch to a rapid amoeboid migration mode, allowing efficient trafficking to lymph nodes and subsequent T cell activation.
DC migration is tightly linked to the presence and dynamics of adhesion structures, including podosomes, characteristic of immature DCs, and focal adhesions (FAs). These structures mediate interactions with the extracellular matrix (ECM), thereby regulating cell adhesion and motility. In addition, podosomes serve as sites of localized secretion of matrix metalloproteinases, facilitating ECM degradation and remodeling.
The organization and function of podosomes and FAs depend on the dynamics of the actin cytoskeleton, which provides structural support, and microtubules, which regulate their spatial organization and turnover. Despite their importance, the mechanisms governing cytoskeletal control of these structures remain incompletely understood.
In this study, we investigated how perturbations in actin and microtubule dynamics affect adhesion structure organization, proteolytic activity, and DC migration. Pharmacological inhibitors of the cytoskeleton combined with quantitative analysis of microscopy images were used to assess adhesion structures, ECM degradation, and 2D migration of murine DCs generated in the presence of GM-CSF.
Our results show that actin depolymerization leads to a complete loss of podosomes, whereas disruption of microtubule dynamics induces their reorganization and reversible elongation of focal adhesions, particularly evident after 2 h of inhibitor treatment. Actin cytoskeleton integrity is essential for ECM degradation and podosome-dependent migration, while microtubules play a modulatory role by regulating adhesion structure organization and DC motility.