Spatiotemporal dynamics of actin-rich adhesion microdomains: influence of substrate flexibility

• DOI: 10.1242/jcs.02838
• Publication Date: 2006-04-24T16:29:27Z
• Authors: Olivier Collin; Philippe Tracqui; Angélique Stephanou; Yves Usson; Jocelyne Clément...; Emmanuelle Planus
• Keywords: 0301 basic medicine; 570; Cytochalasin D; Time Factors; Surface Properties; Recombinant Fusion Proteins; Cell Culture Techniques; [SDV.CAN]Life Sciences [q-bio]/Cancer; MESH: Actins; MESH: Cell Adhesion; Mice; 03 medical and health sciences; [SDV.CAN] Life Sciences [q-bio]/Cancer; MESH: Nucleic Acid Synthesis Inhibitors; MESH: Recombinant Fusion Proteins; MESH: Cytoskeleton; Cell Adhesion; Animals; MESH: Animals; MESH: Mice; Cytoskeleton; Nucleic Acid Synthesis Inhibitors; MESH: Surface Properties; MESH: Cell Culture Techniques; MESH: Time Factors; Cell Membrane; Actins; MESH: Cytochalasin D; NIH 3T3 Cells; MESH: Cell Membrane; MESH: NIH 3T3 Cells

In this study we analyse the formation and dynamics of specific actin-rich structures called podosomes. Podosomes are very dynamic punctual adhesion sites tightly linked to the actin cytoskeleton. Mechanical properties of substrates are emerging as important physical modulators of anchorage-dependent processes involved in the cellular response. We investigate the influence of substrate flexibility on the dynamic properties of podosomes. We used mouse NIH-3T3 fibroblasts, transfected with GFP-actin and cultured on polyacrylamide collagen-coated substrates of varying stiffness. Static and dynamic features of cell morphologies associated with an optical flow analysis of the dynamics of podosomes revealed that: (1) they have constant structural properties, i.e. their shape factor and width do not change with the substrate flexibility; (2) the lifespan of podosomes and mean minimum distance between them depend on the substrate flexibility; (3) there is a variation in the displacement speed of the rosette of podosomes. Moreover, the rosettes sometimes appear as periodically emergent F-actin structures, which suggests that a two-level self-organisation process may drive first, the formation of clusters of podosomes and second, the organisation of these clusters into oscillating rings. Such dynamic features give new perspectives regarding the potential function of podosomes as mechanosensory structures.