Abstract 21393: Nitric Oxide Regulates Pde5 Expression Through Its S-nitrosylation
We recently have found that PDE5 protein expression is regulated by oxidative stress in the failing heart. Since increased superoxide anion can reduce nitric oxide bioavailability, the purpose of this study was to determine whether decreased nitric oxide bioavailability could affect PDE5 expression. Subsequently, we determined the myocardial PDE5 expression in eNOS gene deficient (KO) mice and the result showed that myocardial PDE5 expression was significantly increased in eNOS KO mice. DDAH1 regulates NO production by degrading endogenous NOS inhibitors ADMA and L-NMMA. We have demonstrated that DDAH1 plays an essential role in degrading ADMA and L-NMMA, and DDAH1 gene deletion attenuated degradation of ADMA/L-NMMA to decrease NO production. We determined myocardial PDE5 expression in our DDAH1 KO mice, and the result demonstrated that DDAH1 KO caused increase of myocardial ADMA and L-NMMA, decrease of NO production and increase of PDE5 expression. To understand the molecular mechanism of nitric oxide in regulating PDE5 expression, we further tested the hypothesis that NO regulates PDE5a degradation through S-nitrosylation. Using both cardiac myocyte cell line HL-1 cells and neonatal myocytes, we found that NO donors (SNP, DETA-NO, GSNO) significantly decreased PDE5a protein expression, while NOS inhibitor (CAPTIO and LNAME) significantly increased PDE5a protein expression. The down regulation of PDE5a by NO donor GSNO in HL-1 cells was abolished by proteasome inhibitor MG132, indicating NO facilitates PDE5 degradation. NO donors (GSNO and SNP) increased S-nitrosylation of PDE5a in HL-1 cells as detected by biotin switch assay. Furthermore, PDE5 ubiquitination was increased in HL-1 cells in response to GSNO and MG132. Together, these findings indicate that nitric oxide not only increase cGMP production through activation of soluble guanylate cyclase, it also regulate cGMP content through regulation of PDE5 degradation and stability.
- © 2010 by American Heart Association, Inc.