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Signaling mechanisms involved in protease‐activated receptor‐1 mediated nitric oxide production.
Author(s) -
Watts Vabren L,
Motley Evangeline D
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.816.8
Subject(s) - enos , phosphorylation , nitric oxide , thrombin , microbiology and biotechnology , nitric oxide synthase , receptor , chemistry , nitric oxide synthase type iii , signal transduction , agonist , biochemistry , medicine , pharmacology , biology , endocrinology , platelet
Protease‐activated receptors (PARs) are G protein‐coupled receptors that are known to regulate endothelial nitric oxide synthase (eNOS) activity by phosphorylating the enzyme at various sites. Phosphorylation of eNOS‐Thr495 negatively regulates eNOS activity by causing a decrease in nitric oxide (NO) production. Currently, the mechanisms for eNOS‐Thr495 phosphorylation by PAR agonists are unknown. In this study, we used a specific synthetic PAR‐1 activating peptide, TFLLR, and thrombin to assess the role of PAR‐1 involvement in NO production in endothelial cells. Both agonists phosphorylated Thr495 in a time‐ and concentration‐dependent manner. Also, cells pretreated with a PAR‐1 inhibitor, showed a significant decrease in thrombin and TFLLR‐induced phosphorylation of eNOS Thr495. Rho and Rho‐Kinase inhibitors also caused a significant decrease in PAR‐1‐induced Thr495 phosphorylation. In addition, we observed that both PAR‐1 agonists caused a significant decrease in nitrite production, whereas inhibition of PAR‐1, Rho, and ROCK caused a significant increase in PAR‐1 agonist‐mediated nitrite production. This suggests that PAR‐1 induces phosphorylation of eNOS‐Thr495 and inhibition of NO production via a Rho/ROCK dependent pathway. These findings will contribute to understanding the signaling pathways that regulate eNOS‐induced nitric oxide production. NIH‐NCRR 2G12RR03032.