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Signaling Mechanisms of Protease‐Activate Receptor‐1 Mediated Phosphorylation of Endothelial Nitric Oxide Synthase
Author(s) -
Watts Vabren L.,
Eguchi Satoru,
Motley Evangeline D.
Publication year - 2008
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.22.1_supplement.1215.6
Subject(s) - enos , phosphorylation , microbiology and biotechnology , nitric oxide , thrombin , nitric oxide synthase , nitric oxide synthase type iii , chemistry , signal transduction , receptor , protease activated receptor , umbilical vein , biochemistry , biology , medicine , endocrinology , platelet , in vitro
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. Ser1177 is a positive regulatory site when phosphorylated, whereas, Thr495 phosphorylation negatively regulates eNOS activity. The mechanism for eNOS Thr495 phosphorylation by PAR agonists is 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 the phosphorylation of eNOS Thr495 in human umbilical vein endothelial cells. Both agonists phosphorylated Thr495 in a time‐ and concentration‐dependent manner. Also, cells pretreated with the PAR‐1 inhibitor, SCH79797, showed a significant decrease in thrombin and TFLLR‐induced phosphorylation of eNOS Thr495. Inhibition of Rho with C3 exoenzyme and Rho‐Kinase with Y‐27632 also caused a significant decrease in thrombin and TFLLR‐induced Thr495 phosphorylation. This suggests that PAR‐1 phosphorylates eNOS Thr495 via activation of G12/13. These findings will contribute to understanding the signaling pathways that regulate eNOS‐induced nitric oxide production. NIH‐SCORE.