title: Long-term up-regulation of eNOS and improvement of endothelial function by inhibition of the ubiquitin-proteasome pathway.
abstract: The ubiquitin-proteasome system is the major pathway for intracellular protein degradation in eukaryotic cells. Endothelial nitric oxide synthase (eNOS) is the key enzyme of vascular homeostasis involved in the pathophysiology of several cardiovascular diseases. The aim of our study was to investigate whether eNOS expression and activity are regulated by the proteasome. Bovine pulmonary artery endothelial cells (CPAE cells) were treated with the proteasome inhibitor MG132. MG132 (50-250 nmol/L) dose-dependently increased mRNA and protein levels of eNOS. Comparable results were obtained with other specific proteasome inhibitors, whereas the nonproteasomal calpain and cathepsin inhibitor ALLM had no effect. Efficacy of proteasome inhibition was evidenced by accumulation of poly-ubiquitinylated proteins and by measuring proteasomal activity in cell extracts. Cycloheximide prevented up-regulation of eNOS protein, indicating that post-translational stabilization of eNOS is not involved. eNOS activity was increased up to 2.8-fold (MG132 100 nmol/L, 48 h). Incubation of rat aortic rings with MG132 significantly enhanced endothelial-dependent vasorelaxation. Single MG132 treatment (100 nmol/L) induced long-term effects in CPAE cells, with increases of eNOS protein and activity for up to 10 days. Our results indicate that low-dose proteasome inhibition enhances eNOS expression and activity, and improves endothelial function.
authors.affiliation: Medizinische Klinik mit Schwerpunkt Kardiologie, Angiologie, Pneumologie, Humboldt-Universität Berlin, Charité, Campus Mitte, Schumannstr. 20-21, D-10117 Berlin, Germany. verena.stangl@charite.de
authors.forename: Verena
authors.initials: V
authors.lastname: Stangl
authors.forename: Mario
authors.initials: M
authors.lastname: Lorenz
authors.forename: Silke
authors.initials: S
authors.lastname: Meiners
authors.forename: Antje
authors.initials: A
authors.lastname: Ludwig
authors.forename: Cornelia
authors.initials: C
authors.lastname: Bartsch
authors.forename: Minoo
authors.initials: M
authors.lastname: Moobed
authors.forename: Angelika
authors.initials: A
authors.lastname: Vietzke
authors.forename: Hans-Tilmann
authors.initials: HT
authors.lastname: Kinkel
authors.forename: Gert
authors.initials: G
authors.lastname: Baumann
authors.forename: Karl
authors.initials: K
authors.lastname: Stangl
mesh_terms: D000818:Animals; D002417:Cattle; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D004790:Enzyme Induction / Q000187:drug effects*; D007976:Leupeptins / Q000494:pharmacology*; D008297:Male; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D046988:Proteasome Endopeptidase Complex; D011651:Pulmonary Artery; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D025801:Ubiquitin / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D014664:Vasodilation
chemical_list: D007976:Leupeptins; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D025801:Ubiquitin; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde