Caveolin-1 stabilizes ATP7A, a copper transporter for extracellular SOD, in vascular tissue to maintain endothelial function

• Published in: American Journal of Physiology: Cell Physiology 2020-11, Vol.319 (5), p.C933-C944
• Main Authors: Sudhahar, Varadarajan, Okur, Mustafa Nazir, O'Bryan, John P, Minshall, Richard D, Fulton, David, Ushio-Fukai, Masuko, Fukai, Tohru
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants; Aorta - cytology; Aorta - metabolism; ATP7A protein; Caveolae; Caveolin; Caveolin 1 - deficiency; Caveolin 1 - genetics; Caveolin-1; Copper; Copper - pharmacology; Copper Transport Proteins - genetics; Copper Transport Proteins - metabolism; Copper-Transporting ATPases - genetics; Copper-Transporting ATPases - metabolism; Endothelial cells; Endothelial Cells - cytology; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Endothelium; Fibroblasts; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; Gene Expression Regulation; Gene transfer; Lipid rafts; Male; Mesenteric Arteries - cytology; Mesenteric Arteries - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; mRNA; NAD(P)H oxidase; Nitric oxide; Nitric-oxide synthase; Oxidants; Oxidative Stress; Primary Cell Culture; Proteasome Endopeptidase Complex - metabolism; Proteasomes; Proteins; Proteolysis; Signal Transduction; Smooth muscle; Superoxide dismutase; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Superoxide Dismutase-1 - genetics; Superoxide Dismutase-1 - metabolism; Supplements; Transgenic mice; Ubiquitination; Ubiquitination - drug effects; Vasodilation; Vasodilation - drug effects
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00151.2020

Caveolin-1 (Cav-1) is a scaffolding protein and a major component of caveolae/lipid rafts. Previous reports have shown that endothelial dysfunction in Cav-1-deficient (Cav-1 ) mice is mediated by elevated oxidative stress through endothelial nitric oxide synthase (eNOS) uncoupling and increased NADPH oxidase. Oxidant stress is the net balance of oxidant generation and scavenging, and the role of Cav-1 as a regulator of antioxidant enzymes in vascular tissue is poorly understood. Extracellular SOD (SOD3) is a copper (Cu)-containing enzyme that is secreted from vascular smooth muscle cells/fibroblasts and subsequently binds to the endothelial cells surface, where it scavenges extracellular [Formula: see text] and preserves endothelial function. SOD3 activity is dependent on Cu, supplied by the Cu transporter ATP7A, but whether Cav-1 regulates the ATP7A-SOD3 axis and its role in oxidative stress-mediated vascular dysfunction has not been studied. Here we show that the activity of SOD3, but not SOD1, was significantly decreased in Cav-1 vessels, which was rescued by re-expression of Cav-1 or Cu supplementation. Loss of Cav-1 reduced ATP7A protein, but not mRNA, and this was mediated by ubiquitination of ATP7A and proteasomal degradation. ATP7A bound to Cav-1 and was colocalized with SOD3 in caveolae/lipid rafts or perinucleus in vascular tissues or cells. Impaired endothelium-dependent vasorelaxation in Cav-1 mice was rescued by gene transfer of SOD3 or by ATP7A-overexpressing transgenic mice. These data reveal an unexpected role of Cav-1 in stabilizing ATP7A protein expression by preventing its ubiquitination and proteasomal degradation, thereby increasing SOD3 activity, which in turn protects against vascular oxidative stress-mediated endothelial dysfunction.