Carbon monoxide induces a late preconditioning-mimetic cardioprotective and antiapoptotic milieu in the myocardium

A growing body of evidence indicates that carbon monoxide (CO), once perceived merely as a poisonous gas, exerts antiapoptotic and cytoprotective effects. Using a water-soluble CO-releasing molecule (CORM) tricarbonylchloro(glycinato)ruthenium(II) (CORM-3), we previously reported that CO induces a delayed protection against myocardial infarction similar to that observed in the late phase of ischemic preconditioning (PC). In the current study, we investigated the molecular mechanisms underlying this cardioprotective effect. The impact on apoptotic signaling pathways was first examined in the setting of ischemia/reperfusion injury. Mice were pretreated with CORM-3 or iCORM-3 (which does not release CO) and subjected to coronary occlusion/reperfusion 24h later. In mice that received CORM-3, there was a significant reduction in markers of apoptosis (cleaved lamin A, cleaved caspase-3, and cleaved PARP-1) after ischemia/reperfusion injury. To elucidate the mechanism of CORM-3-induced cardioprotection we further examined the activation of transcription factors and induction of cardioprotective and apoptosis modulating proteins. Infusion of CORM-3 rapidly activated the stress-responsive transcription factors nuclear factor kappaB (NF-κB), signal transducers and activators of transcription (STAT)1, STAT3, and NF-E2-related factor-2 (Nrf2). This was followed 24h later by upregulation of cardioprotective proteins (heme oxygenase-1 [HO-1], cyclooxygenase-2 [COX-2], and extracellular superoxide dismutase [Ec-SOD]) and antiapoptotic proteins involving both the mitochondria-mediated (Mcl-1) and the death receptor-mediated (c-FLIP _S and c-FLIP _L) apoptosis pathways. We conclude that CO released by CORM-3 triggers a cardioprotective signaling cascade that recruits the transcription factors NF-κB, STAT1/3, and Nrf2 with a subsequent increase in cardioprotective and antiapoptotic molecules in the myocardium leading to the late PC-mimetic infarct-sparing effects. This article is part of a Special Issue entitled 'Possible Editorial'.