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Caveolin‐1 nitrosation and degradation results in eNOS uncoupling, endothelial dysfunction, and nitrate tolerance (851.18)
Author(s) -
Mao Mao,
Varadarajan Sudhahar,
Fukai Tohru,
Bakhshi Farnaz,
Chernaya Olga,
Dudley Samuel,
Minshall Rich,
Bonini Marcelo
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.851.18
Subject(s) - enos , peroxynitrite , caveolin 1 , nitric oxide , mg132 , chemistry , nitric oxide synthase type iii , endothelial dysfunction , vasodilation , oxidative stress , endothelium , medicine , microbiology and biotechnology , endocrinology , pharmacology , biochemistry , nitric oxide synthase , proteasome , proteasome inhibitor , biology , enzyme , superoxide
Prolonged treatment with nitroglycerin (GTN) has been shown to induce nitrate tolerance and cross‐tolerance. However, much of the mechanism of how GTN leads to tolerance remains unknown. Recent evidence indicates that GTN induced endothelial‐dependent vasodilation requires endothelial nitric oxide synthase (eNOS) activation. Thus, we hypothesized that eNOS dysfunction as a result of continuous GTN exposure might underlie nitrate tolerance. Caveolin‐1 (CAV‐1) is known to interact with eNOS and regulate eNOS function. Loss of caveolin‐1 results in eNOS hyper‐activation which evolves into eNOS dysfunction and converts the enzyme into a source of oxidative stress. In this study we investigated the roles of CAV‐1 and eNOS in tolerance. We report that when endothelial cells are continuously exposed to GTN, eNOS becomes a source of peroxynitrite secondary to CAV‐1 depletion. We demonstrate that CAV‐1 is nitrosated and degraded in both GTN treated endothelial cells and animal tissues which parallels a marked increase in eNOS phosphorylation (Ser 1177) and accumulation of monomeric eNOS. We also demonstrate in endothelial cells that although CAV‐1 mRNA level is not changed, ubiquitination on the protein is increased with GTN, and that treatment of the proteasome inhibitor MG132 partially restores CAV‐1 levels which indicates that GTN‐induced CAV‐1 loss is due to post‐translational modification‐dependent degradation. We also confirmed that eNOS is dysfunctional in the CAV‐1 knockout mouse, which is naturally tolerant to pharmacologically relevant doses of GTN. Moreover, we show that elevated production of peroxynitrite from dysregulated eNOS is abolished upon rescue of CAV‐1 expression suggesting that eNOS may be uncoupled in the absence of CAV‐1. Taken together, these results imply that GTN‐induced CAV‐1 depletion and subsequent eNOS dysfunction can give rise to nitrate tolerance. Grant Funding Source : Supported by American Heart Association (AHA)