The ESCRT machinery

Do caveolae regulate signaling pathways? The broad spectrum of signaling pathways sensitive to caveolae or caveolins is remarkable, with impacts on gene expression, cell proliferation, anchorage dependence of cell growth, directional cell migration, extracellular matrix remodeling, and so on. Since caveolins are also found outside of caveolae, some of the functions assigned to caveolin may not be related to caveolae, but it is clear that caveolae directly regulate numerous signaling pathways. Two types of mechanism have been described by which caveolae finetune or activate/deactivate signaling cascades. One is the differential lateral plasma membrane distribution of signaling molecules within or outside of caveolae. The second is the movement of caveolae residents between the cell surface and interior due to the translocation of caveolae between the plasma membrane and the endomembrane system, where caveolae presumably lose their characteristic shape. In both cases, the change in localization results in different signaling outputs. Signaling molecules (membrane receptors, non-receptor kinases and adaptors) can be recruited to caveolae through direct binding to caveolins or by caveolin-independent mechanisms.