Reexpression of caveolin-1 in endothelium rescues the vascular, cardiac, and pulmonary defects in global caveolin-1 knockout mice

Abstract

Caveolin-1 (Cav-1) is the principal structural component of caveolae organelles in smooth muscle cells, adipocytes, fi broblasts, epithelial cells, and endothelial cells (ECs). Cav-1 -defi cient (Cav-1 knockout [KO]) mice are viable and show increases of nitric oxide (NO) production in vasculature, cardiomyopathy, and pulmonary dysfunction. In this study, we generated EC-specifi c Cav-1 -reconstituted (Cav-1 RC) mice and reexamined vascular, cardiac, and pulmonary phenotypes. Cav-1 KO pulmonary arteries had decreased smooth muscle contractility and increased endothelial NO synthase activation and hypotension; the latter two effects were rescued completely in Cav-1 RC mice. Cav-1 KO mice exhibited myocardial hypertrophy, pulmonary hypertension, and alveolar cell hyperproliferation caused by constitutive activation of p42/44 mitogen-activated protein kinase and Akt. Interestingly, in Cav-1 RC mice, cardiac hypertrophy and pulmonary hypertension were completely rescued, whereas alveolar hyperplasia was partially recovered because of the lack of rescue of Cav-1 in bronchiolar epithelial cells. These results provide clear physiological evidence supporting the important role of cell type -specifi c Cav-1 expression governing multiple phenotypes in the vasculature, heart, and lung. 2374 REGULATION OF PARENCHYMAL FUNCTIONS BY ENDOTHELIAL CAVEOLIN-1 | Murata et al.WT arteries under resting and Ach-stimulated conditions (3 M for 3 min). Again, EC-specifi c Cav-1 RC suppressed this increase in cGMP. In all of the strains, the sensitivity of the soluble guanylyl cyclase was normal because the increases in cGMP production in response to the NO donor sodium nitroprusside (1 M for 3 min) were similar. channels; these eff ects are rescued by breeding global Cav-1 KO to EC-specifi c Cav-1 transgenic (TG) mice ( 15 ) to reconstitute Cav-1 (called Cav-1 RC) back into the endothelium ( 11,16 ). We show that EC-specifi c Cav-1 reconstitution corrects the abnormal vasomotion in vessels and the cardiac and pulmonary abnormalities observed in Cav-1 KO mice, demonstrating that the diverse cardiovascular phenotypes in these mice are attributable to caveolae in the endothelium and not to other cell types that express Cav-1. RESULTS Generation of TG mice expressing EC Cav-1 on a Cav-1 -defi cient backgroundTo assess the eff ects of Cav-1/caveolae on vascular, lung, and cardiac phenotypes, mice defi cient in Cav-1 were bred to TG mice expressing Cav-1 in ECs alone, as previously reported ( 11,16 ). Fig. 1 A documents Cav-1 protein expression in intrapulmonary arteries isolated from these mice. WT mice demonstrate the presence of Cav-1 ( Fig. 1 A , left column, green channel) predominantly in the endothelium and lower levels in smooth muscle ( n ϭ 5; Fig. 1 A, top, Cav-1 alone; middle, labeling of smooth muscle ␣ -actin [red] and nuclei [DAPI, blue]; bottom, merged images), whereas Cav-1 KO mice (middle column) lack Cav-1 immunostaining in both layers ( n ϭ 5). Reconstitution of Cav-1 into the endothelium generated by crossing Cav-1 KO...

Increased pulmonary vascular resistance and defective pulmonary artery filling in caveolin-1−/−mice

“…eNOS is activated in Cav1 Ϫ/Ϫ mice, and this can be reversed by endothelial-specific reconstitution of caveolin-1 expression (23). Even though caveolin-1 can interact with all three known NOS isoforms (12), their expression is not upregulated in the absence of caveolin-1 (8,28,40).…”

Role of caveolin-1 in endothelial BKCa channel regulation of vasoreactivity

“…Importantly, Cav-1 inhibits BK Ca channel activity in cultured ECs (35) through its scaffolding domain (amino acids 82-101: DGIWKASFTTFTVTKYWFYR); however, the role of Cav-1 in BK Ca channel function in native ECs has not been examined, and Cav-1 regulates BK Ca channels differently in other cell types. Cav-1 knockout mice develop cardiac hypertrophy, pulmonary hypertension, and systemic hypotension (24). Additionally, Cav-1 knockout mice demonstrate augmented endothelium-dependent relaxation (7,36) and decreased myogenic (1) and agonist-induced (7) vasoconstriction, which parallels observations in CH-exposed rats (9,11,16).…”

High-molecular-weight hyaluronan is a novel inhibitor of pulmonary vascular leakiness

“…CEM, also termed detergent-resistant membranes or caveolae, have been implicated in a variety of cellular functions, including potocytosis, cholesterol and Ca 2ϩ regulation, and signal transduction (27,42,43,47). Deletion of caveolin-1 expression in mice inhibits CEM (caveolae) formation in EC and promotes lung pathology (13,17,24,30,49,52,59).…”

“…CEM, also termed detergent-resistant membranes or caveolae, have been implicated in a variety of cellular functions, including potocytosis, cholesterol and Ca 2ϩ regulation, and signal transduction (27,42,43,47). Deletion of caveolin-1 expression in mice inhibits CEM (caveolae) formation in EC and promotes lung pathology (13,17,24,30,49,52,59).In this study, we utilized several novel techniques, including quantitative proteomic analysis and in vivo models of lung injury utilizing knockout mice and angiotensin I-converting enzyme (ACE) antibody-conjugated liposomal delivery of CD44 small interfering RNA (siRNA), to determine CD44/ CEM regulation of HMW-HA-mediated EC barrier function. Increased insights into mechanism(s) by which HMW-HA promotes increased EC barrier function will propel development of novel treatments for disorders characterized by marked vascular barrier disruption.…”