Abstract
Invadopodia and podosomes have been intensively studied because of their involvement in the degradation of extracellular matrix. As both structures have been studied mostly on thin matrices, their commonly reported shapes and characteristics may differ from those in vivo.
To assess the morphology of invadopodia in a complex 3D environment, we observed invadopodial formation in cells grown on a dense matrix based on cell-free dermis. We have found that invadopodia differ in morphology when cells grown on the dermis-based matrix and thin substrates are compared.
The cells grown on the dermis-based matrix display invadopodia which are formed by a thick protruding base rich in F-actin, phospho-paxillin, phospho-cortactin and phosphotyrosine signal, from which numerous thin filaments protrude into the matrix. The protruding filaments are composed of an F-actin core and are free of phospho-paxillin and phospho-cortactin but capped by phosphotyrosine signal.