Abstract 16552: Hydrogen Sulfide-Mediated Reduction of Enos Tyrosine Phosphorylation:Implications for Cardioprotection
Introduction: Hydrogen sulfide (H2S) exhibits beneficial effects in the cardiovascular system. Many of its actions have been shown to depend on endogenously produced nitric oxide (NO) and extensive cross-talk between H2S and NO signaling has been shown to occur in the heart and blood vessels.
Hypothesis: Herein, we investigated a novel mechanism of H2S-NO interaction in the ischemic heart. We sought to evaluate whether H2S modulates proline rich kinase 2 (PYK2)-induced eNOS phoshporylation and to evaluate the functional role of the H2S/PYK2/eNOS axis on myocardial injury.
Methods & Results: Exposure of differentiated H9c2 cardiomyocytes to H2O2 increased PYK2 phosphorylation on its activator site and promoted inhibition of eNOS activity by increasing Y657 phosphorylation. The effect of H2O2 was blocked by treatment with a H2S donor. Cell viability assays revealed increased cell survival of H9c2 under oxidative stress or oxygen-glucose deprivation/recovery injury upon PYK2 silencing; this effect was reversed by inhibiting NO production. Inhibiting endogenous H2S production by AOAA, increased PYK2 and eNOS phosphorylation in cells exposed to H2O2. In contrast, incubation of cells with L-cycteine (a substrate for H2S generation), lead to a reversal of the H2O2 effects. Silencing PYK2 restored cell viability in cells treated with AOAA. In vivo ischemia-reperfusion resulted in PYK2 and eNOS Y657 phosphorylation during early reperfusion; under these conditions, reduced NO levels were observed, as judged by the decrease in tissue cGMP levels. Inhibition of PYK2 by PF-431396 reduced eNOS Y657 phosphorylation and increased cGMP in early reperfusion. Na2S administration reduced reactive oxygen species formation leading to reduced PYK2 and eNOS Y657 phosphorylation. Pharmacological blockade of PYK2 or inhibition of PYK2 activation by Na2S reduced infarct size in mice (36.8±2.0% for control group, 18.0±0.9% for PF-431396 group and 17.8±1.6% for Na2S group, p<0.05). Co-administration of the PYK2 inhibitor and Na2S did not exert any additional beneficial effects on infarct size (20.2±2.5%).
Conclusions: Our study identifies H2S as a regulator of the PYK2/eNOS axis in myocardial infarction and proposes PYK2 as a therapeutic target for cardioprotection.
Author Disclosures: S. Bibli: None. A. Chatzianastasiou: None. A. Papapetropoulos: None.
- © 2016 by American Heart Association, Inc.