Knock down of caveolin-1 affects morphological and functional hallmarks of human endothelial cells

Caveolin-1 (CAV1) is the principal structural component of caveolae which functions as scaffolding protein for the integration of a variety of signaling pathways. In this study, we investigated the involvement of CAV1 in endothelial cell functions and show that siRNA-induced CAV1 silencing in the human EC line EA.hy926 induces distinctive morphological changes, such as a marked increase in cell size and formation of stress fibers. Design-based stereology was employed in this work to make unbiased quantification of morphometric properties such as volume, length and surface of CAV1 silenced vs. control cells. In addition, we showed that down regulation CAV1 affects cell cycle progression at G1/S phase transition most likely by perturbation of AKT signaling. With the aim to assess the contribution of CAV1 to typical biological processes of EC, we report here that CAV1 targeting affected cell migration and matrix metalloproteinases (MMPs) activity, and reduced angiogenesis in response to VEGF, in vitro. Taken together our data suggest that the proper expression of CAV1 is important not only for maintaining the appropriate morphology and size of endothelial cells but it might represent a prospective molecular target for studying key biological mechanisms such as senescence and tumorigenesis.