Podosomes in endothelial cell-microenvironment interactions

Purpose of review The discovery of podosomes in endothelial cells during the process of angiogenesis in vivo opens a new era in vascular biology. Podosomes are actin-based microdomains located at the plasma membrane that have been extensively described but in vitro and in other cells. This review focuses on podosomes in endothelial cells and aims to rise hypotheses about when and how these structures mediate cell--microenvironment interactions. Recent findings A wealth of new information regarding podosome organization and functioning has been collected in simple 2D models. Characterization of their modular architecture has unravelled their mechanics. However, context matters and podosome characteristics and functioning are shaped by the microenvironment. Although matrix degradation was seen as the typical function of podosomes, mechanosensing now appears equally prominent and involved in setting of the proteolytic machinery. Endothelial podosomes breach the basement membrane, and are thus, involved in vascular remodelling. Summary In endothelial cells, podosomes are involved in breaking up the basement membrane, giving the cells the opportunity to invade adjacent tissues and to engage in new cell-cell interactions. Such functions are particularly relevant to vascular biology and the exploration of podosomes in in vivo settings should bring clues to many unanswered questions.