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Caveolin‐1 regulates eNOS derived superoxide production under condition of tetrahydrobiopterin depletion and oxidation
Author(s) -
Karuppiah Kanchana,
Druhan Lawrence,
Kearns Patrick,
Brabham Dione,
Cardounel Arturo
Publication year - 2009
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.23.1_supplement.628.10
Subject(s) - enos , superoxide , tetrahydrobiopterin , chemistry , biopterin , medicine , endocrinology , nitric oxide , biochemistry , microbiology and biotechnology , biology , nitric oxide synthase , enzyme
The paradoxical finding of a concomitant increase in eNOS expression and reduced endothelium‐dependent vasodilation has drawn attention to the fact that eNOS itself in pathological states may be a source of superoxide anions, a process which has been termed "eNOS uncoupling". eNOS uncoupling has been shown to result from oxidation of the critical NOS cofactor, tetrahydrobiopterin (BH4). In the current study, we identified caveolin‐1 as a novel regulator of eNOS derived superoxide under condition of both BH4 oxidation and depletion. In‐vitro results demonstrated that cav‐1 peptide was able to dose dependently inhibit eNOS derived superoxide with >70% inhibition observed at 400nM. Cellular studies demonstrated that pharmacological depletion of endothelial BH4 resulted in an 88% decrease in eNOS derived NO with no significant increase in eNOS derived superoxide. Immunoprecipitation studies demonstrated a 3 fold increase in cav‐1‐eNOS association following BH4 depletion which was hypothesized to sequester and thus prevent uncoupling of pterin‐free eNOS. This was verified using cav‐1 gene silencing techniques which demonstrated a 5 fold increase in eNOS derived superoxide following BH4 depletion. Similar finding were observed under conditions of hyperglycemia which are known to cause oxidation of BH4. These studies identify cav‐1 as a novel regulator of eNOS derived superoxide.