Figure 7.

Models of podosome internal dynamics and podosome self-patterning. The integrins and associated proteins such as vinculin and paxillin surround the actin core and presumably induce the formation of a patch of cortactin/WASP-Arp2/3 that controls the actin polymerization. The actin core of the podosome is produced by the combined action of actin polymerization and actin severing. During osteoclastogenesis, rings start to from inside clusters and expand. The ring dynamics constantly induce the formation of new podosomes at its outer ridge while inhibiting new podosomes to form inside. This mechanism drives progressively the formation of podosomes at the cell periphery. A functional microtubule network is needed to stabilize the podosome belt at the cell periphery.