Targeted disruption of Pde3b, but not Pde3a, protects murine heart from ischemia/reperfusion injury: Proteomic approaches to possible mechanisms

Abstract

The Pde3 gene family contains two subfamilies, PDE3A and PDE3B, which are generated from distinct, but closely related, genes. Cilostazol, a PDE3 inhibitor, has been reported to protect rabbit and murine heart against ischemia/reperfusion (I/R) injury. Targeted disruption of Pde3b, but not Pde3a, protected the heart from I/R injury, with significantly improved postischemic recovery of left ventricular developed pressure and reduced infarct size.Cardioprotective signals are thought to be transmitted to mitochondria by specialized vesicular structures, signalosomes, which are assembled in caveolae and lipid rafts and contain various signaling molecules. We therefore performed a comprehensive characterization of ischemia‐induced caveolin‐enriched fractions (ICEF) in mitochondria preparations from Langendorff‐perfused hearts from WT and PDE3B KO mice before/after ischemia, using a combination of subcellular fractionation and isobaric tag for relative and absolute quantitation (iTRAQ). More than 500 ICEF proteins were identified; most of them were mitochondrial. Identified proteins were grouped according to their differential expression: i) no changes before/after ischemia and no differences in wild type and KO hearts, ii) changes after ischemia in both wild type and KO hearts, iii) changes after ischemia only in wild type hearts, and iv) changes after ischemia only in KO hearts. Furthermore, fractions containing the signalosomes were enriched in connexin 43‐containing mitochondrial populations, i.e. subsarcolemmal mitochondria (SSM), not interfibrillar mitochondria (IFM).In conclusion, these data suggest that targeted inactivation of Pde3b modifies composition of signalosomes associated with SSM to exert cardioprotective effects during I/R, and that PDE3B‐selective inhibitors might provide useful therapeutics to limit I/R injury.