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Objective: Endothelial Cav-1 (caveolin-1) expression plays a relevant role during atherogenesis by controlling NO production, vascular inflammation, LDL (low-density lipoprotein) transcytosis, and extracellular matrix remodeling. Additional studies have identified cholesterol-rich membrane domains as important regulators of autophagy by recruiting ATGs (autophagy-related proteins) to the plasma membrane. Here, we investigate how the expression of Cav-1 in the aortic endothelium influences autophagy and whether enhanced autophagy contributes to the atheroprotective phenotype observed in Cav-1-deficient mice. Approach and Results: To analyze the impact of Cav-1 deficiency on regulation of autophagy in the aortic endothelium during the progression of atherosclerosis, we fed Ldlr -/- and Cav-1 -/- Ldlr -/- mice a Western diet and assessed autophagy in the vasculature. We observe that the absence of Cav-1 promotes autophagy activation in athero-prone areas of the aortic endothelium by enhancing autophagic flux. Mechanistically, we found that Cav-1 interacts with the ATG5-ATG12 complex and influences the cellular localization of autophagosome components in lipid rafts, which controls the autophagosome formation and autophagic flux. Pharmacological inhibition of autophagy attenuates the atheroprotection observed in Cav-1 -/- mice by increasing endothelial inflammation and macrophage recruitment, identifying a novel molecular mechanism by which Cav-1 deficiency protects against the progression of atherosclerosis., Conclusions: These results identify Cav-1 as a relevant regulator of autophagy in the aortic endothelium and demonstrate that pharmacological suppression of autophagic flux in Cav-1-deficient mice attenuates the atheroprotection observed in Cav-1 -/- mice. Additionally, these findings suggest that activation of endothelial autophagy by blocking Cav-1 might provide a potential therapeutic strategy for cardiovascular diseases including atherosclerosis.

Endothelial permeability measurements of intact vascular beds and monolayer cultures are used to describe transport of small molecules (ions, water, and nutrients), macromolecules and plasma protein across the vascular endothelia. Disruption of the endothelial barrier leads to vascular hyper-permeability and protein-rich edema which is a key hallmark of inflammation. Transport of the most abundant plasma protein, albumin, occurs by means of transcellular and paracellular pathways. In healthy, noninflamed vessels, endothelial cell-cell contacts significantly restrict the paracellular permeability of albumin, whereas its transcellular transport from the blood to the abluminal perivascular interstitium occurs via caveolae. Thus, caveolae-mediated transport is a primary determinant of the basal endothelial permeability properties. Increased paracellular permeability induced during inflammation is thought to be due to the opening of interendothelial cell-cell junctions and disruption of endothelial cell-matrix contacts within the vasculature. We recently demonstrated that caveolae-mediated transendothelial transport (transcytosis) of macromolecules through the microvascular endothelial barrier is also an important mechanism responsible for inflammation-evoked pulmonary vascular hyperpermeability and protein-rich edema formation. Moreover, caveolin-1, a structural and scaffolding protein required for caveolae formation and transcellular transport, also plays an important role in oxidant-induced paracellular hyperpermeability. This review highlights the methods used to assess transcellular and paracellular permeability properties of the intact mouse lung and cultured endothelial cell monolayers.

Currently, no single marker is sensitive and specific enough to be considered a reliable biomarker for prenatal alcohol exposure. To identify a proteomic signature profile for maternal alcohol consumption, we carried out high-throughput proteomics on maternal endothelial caveolae exposed to moderate binge-like alcohol conditions. In these specialized lipid-ordered microdomains that contain a rich assembly of proteins, we demonstrate that moderate binge-like alcohol resulted in a distinctive maternal caveolar proteomic signature with important proteins being dramatically decreased/knocked out in the alcoholic profile. These proteins span from histones and basic structural proteins like α tubulin to proteins involved in trafficking, deubiquitination, cell signaling, and cell-cell adhesion. The profile also suggests an important role for the mother and the uteroplacental compartment in the pathogenesis of fetal alcohol spectrum disorders (FASD). These data demonstrate that the caveolar proteomic signature created by alcohol shows a promising direction for early detection of FASD., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Several studies have emphasized the relevance of dystrophin-associated protein complex (DAPC) to maintain the vascular function. Previously we postulated the presence of an utrophin associated protein complex (UAPC) in endothelium from umbilical cord vessels. In the present work, we demonstrate that utrophin (UTR) indeed forms a complex, with beta-dystroglycan (DG), epsilon-sarcoglycan (SG), caveolin-1 (cav-1), and endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells (HUVEC) by co-immunoprecipitation analysis. Additionally, we observed an increment in the protein levels of epsilon-SG, beta-DG, UTR and cav-1 after mechanical stretching. Interestingly, this stimulus also induced eNOS up-regulation, activation and release from the UAPC, and led to a significant increase in nitric oxide (NO) production. Finally, we propose that UAPC in HUVECs may play an important role in the regulation of vascular tone.

Cephalic elevations in arterial pressure associated with microgravity and prolonged bed rest alter cerebrovascular autoregulation in humans. Using the head-down tail-suspended (HDT) rat to chronically induce headward fluid shifts and elevate cerebral artery pressure, previous work has likewise shown cerebral perfusion to be diminished. The purpose of this study was to test the hypothesis that 2 wk of HDT reduces cerebral artery vasodilation. To test this hypothesis, dose-response relations for endothelium-dependent (2-methylthioadenosine triphosphate and bradykinin) and endothelium-independent (nitroprusside) vasodilation were determined in vitro in middle cerebral arteries (MCAs) from HDT and control rats. All in vitro measurements were done in the presence and absence of the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (10(-5) M) and cyclooxygenase inhibitor indomethacin (10(-5) M). MCA caveolin-1 protein content was measured by immunoblot analysis. Endothelium-dependent vasodilation to 2-methylthioadenosine triphosphate and bradykinin were both lower in MCAs from HDT rats. These lower vasodilator responses were abolished with N(G)-nitro-L-arginine methyl ester but were unaffected by indomethacin. In addition, HDT was associated with lower levels of MCA caveolin-1 protein. Endothelium-independent vasodilation was not altered by HDT. These results indicate that chronic cephalic fluid shifts diminish endothelium-dependent vasodilation through alterations in the endothelial nitric oxide synthase signaling mechanism. Such decrements in endothelium-dependent vasodilation of cerebral arteries could contribute to the elevations in cerebral vascular resistance and reductions in cerebral perfusion that occur after conditions of simulated microgravity in HDT rats.

Polymorphic mutations in the Bone Morphogenetic Protein type II receptor (BMPrII) gene have been implicated in the development of familial primary pulmonary hypertension (PPH) however, the role BMPrII mutations play in the development of PH has not yet been elucidated. Endothelial caveolae are an important domain of hemodynamics containing eNOS, the serotonin transporter, and endothelin receptors. In this study we show by standard immunohistochemistry (IHC) that BMPrII is widely distributed in the vasculature of the rat lung, and more specifically distributed to both apical and basal membranes of the arteriolar endothelium by fluorescent IHC. We also examined compartmentalization of BMPrII in lipid fractions of plasma membranes isolated by silica based extraction from human pulmonary artery endothelial cells and rat lung endothelium. Density gradient centrifugation demonstrated BMPrII in separate caveolin-1 (cav-1) and non-cav-1 lipid rich fractions. Electron microscopy co-localized cav-1 and BMPrII in flask shaped membrane fragments. Three-dimensional fluorescence microscopy demonstrated BMPrII in discrete membrane foci, a portion of which were co-localized with cav-1, as well as in Golgi. Our findings indicate that BMPrII is located within lipid-dense fractions of pulmonary endothelial cell membranes with a portion present in caveolae suggesting potential dynamic regulatory structural relationships.