In this study, we present results demonstrating that mechanotransduction by vascular endothelial cadherin (VEcadherin, also known as CDH5) complexes in endothelial cells triggers local cytoskeletal remodeling, and also activates global signals that alter peripheral intercellular junctions and disrupt cell-cell contacts far from the site of force application. Prior studies have documented the impact of actomyosin contractile forces on adherens junction remodeling, but the role of VE-cadherin in force sensation and its ability to influence endothelial cell and tissue mechanics globally have not been demonstrated. Using mechanical manipulation of VEcadherin bonds and confocal imaging, we demonstrate VE-cadherinbased mechanotransduction. We then demonstrate that it requires homophilic VE-cadherin ligation, an intact actomyosin cytoskeleton, Rho-associated protein kinase 1 (ROCK1) and phosphoinositide 3-kinase. VE-cadherin-mediated mechanotransduction triggered local actin and vinculin recruitment, as well as global signals that altered focal adhesions and disrupted peripheral intercellular junctions. Confocal imaging revealed that VE-cadherin-specific changes appear to propagate across cell junctions to disrupt distant interendothelial junctions. These results demonstrate the central role of VE-cadherin adhesions and the actomyosin cytoskeleton within an integrated, mechanosensitive network that both induces local cytoskeletal remodeling at the site of force application and regulates the global integrity of endothelial tissues.

The findings presented here demonstrate the role of a-catenin in cadherin-based adhesion and mechanotransduction in different mechanical contexts. Bead-twisting measurements in conjunction with imaging, and the use of different cell lines and a-catenin mutants reveal that the acute local mechanical manipulation of cadherin bonds triggers vinculin and actin recruitment to cadherin adhesions in an actin-and a-catenin-dependent manner. The modest effect of a-catenin on the two-dimensional binding affinities of cell surface cadherins further suggests that forceactivated adhesion strengthening is due to enhanced cadherincytoskeletal interactions rather than to a-catenin-dependent affinity modulation. Complementary investigations of cadherin-based rigidity sensing also suggest that, although a-catenin alters traction force generation, it is not the sole regulator of cell contractility on compliant cadherin-coated substrata.

Microencapsulated API restored normoglycemia for more than 1 year in spontaneously diabetic NODs given dual CoB. To our knowledge, this is the first study to document long-term normalized HbA1c, porcine C peptide, and near normal glucose tolerance in immunosuppressed diabetic NOD mice transplanted intraperitoneally with microencapsulated API. Our study suggests that transplantation of microencapsulated porcine islet xenografts may be a future treatment for patients with type 1 diabetes mellitus.

No abstract

SummaryThis study investigated the impact of cadherin binding differences on both cell sorting and GTPase activation. The use of N-terminal domain point mutants of Xenopus C-cadherin enabled us to quantify binding differences and determine their effects on cadherindependent functions without any potential complications arising as a result of differences in cytodomain interactions. Dynamic cell-cell binding measurements carried out with the micropipette manipulation technique quantified the impact of these mutations on the twodimensional binding affinities and dissociation rates of cadherins in the native context of the cell membrane. Pairwise binding affinities were compared with in vitro cell-sorting specificity and ligation-dependent GTPase signaling. Two-dimensional affinity differences greater than five-fold correlated with cadherin-dependent in vitro cell segregation, but smaller differences failed to induce cell sorting.Comparison of the binding affinities with GTPase signaling amplitudes further demonstrated that differential binding also proportionally modulates intracellular signaling. These results show that differential cadherin affinities have broader functional consequences than merely controlling cell-cell cohesion.