Caveolae and non-caveolae lipid raft microdomains of human umbilical vein endothelial cells contain utrophin-associated protein complexes

Several studies have shown the importance of dystrophin-associated protein complex in the development of muscular dystrophies and dilated cardiomyopathy associated to vascular dysfunction. In vascular endothelium, dystrophin is substituted for utrophin (autosomal homolog of dystrophin); however, its role in this tissue is unknown. Therefore, it is important to obtain a more extensive knowledge of utrophin and its associated proteins in endothelial cells. In a previous study, we demonstrated the presence of utrophin-associated protein complex (UAPC) in human umbilical vein endothelial cells HUVEC, which interacts with caveolin-1 (Cav-1) and endothelial nitric oxide synthase (eNOS). Also, some of our observations suggested the presence of this complex in distinct membrane domains. Therefore, the aim of this study was to analyze the presence of the UAPC in caveolae and non-caveolae lipid rafts domains of HUVEC at baseline and with a mechanical stimulus. It was demonstrated, by subcellular fractionation and co-immunoprecipitation assays, the association of UAPC with Cav-1 and eNOS in caveolae domains, as well as its interaction with eNOS in non-caveolae lipid raft domains. Additionally, it was also observed that mechanical stress on endothelial cells induced activation and release of eNOS from both caveolae and non-caveolae lipid raft associated to UAPC. Together these results suggest that UAPC located in caveolae and non-caveolae lipid raft domains of HUVECs may have a mechanosensory function that could participate in the control of eNOS activity.