Mechanotransduction at the basis of endothelial barrier function

Destabilization of cell-cell contacts involved in the maintenance of endothelial barrier function can lead to increased endothelial permeability. This increase in endothelial permeability results in an anarchical movement of fluid, solutes and cells outside the vasculature and into the surrounding tissues, thereby contributing to various diseases such as stroke or pulmonary edema. Thus, a better understanding of the molecular mechanisms regulating endothelial cell junction integrity is required for developing new therapies for these diseases. In this review, we describe the mechanotransduction mechanism at the basis of adherens junction strengthening at endothelial cell-cell contacts. More particularly, we report on the emerging role of α-catenin and EPLIN that act as a mechanotransmitter of myosin-IIgenerated traction forces. The interplay between α-catenin, EPLIN and the myosin-II machinery initiates the junctional recruitment of vinculin and α-actinin leading to a drastic remodeling of the actin cytoskeleton and to cortical actin ring reshaping. The pathways initiated by tyrosine phosphorylation of VE-cadherin at the basis of endothelial cell-cell junction remodeling is also reported, as it may be interrelated to α-catenin/ EPLIN-mediated mechanotransduction mechanisms. We also describe the junctional mechanosensory complex composed of PECAM-1, VE-cadherin and VEGFR2 that is able to transmit signaling pathway under the onset of shear stress. This mechanosensing mechanism, involved in the earliest events promoting atherogenesis, is required for endothelial cell alignment along flow direction.