Role of heme oxygenase-1 in the cardioprotective effects of erythropoietin during myocardial ischemia and reperfusion

Abstract

of heme oxygenase-1 in the cardioprotective effects of erythropoietin during myocardial ischemia and reperfusion. Am J Physiol Heart Circ Physiol 296: H84 -H93, 2009; doi:10.1152/ajpheart.00372.2008.-We have recently demonstrated that erythropoietin (EPO) protects cardiomyocytes from apoptosis during myocardial ischemia-reperfusion (I/R). The objective of the present study was to investigate the role of heme oxygenase (HO)-1 in the antiapoptotic effects of EPO. Primary cultures of neonatal mouse cardiomyocytes were subjected to anoxiareoxygenation (A/R). Pretreatment with EPO significantly reduced apoptosis in A/R-treated cells. This reduction in apoptosis was preceded by an increase in the mRNA and protein expression of HO-1. Selective inhibition of HO-1 using chromium mesoporphyrin (CrMP) significantly diminished the ability of EPO to inhibit apoptosis. Cotreatment of EPO with SB-202190, an inhibitor of p38 activation, blocked the EPO-mediated HO-1 expression and antiapoptotic effects, suggesting a p38-dependent mechanism. The in vivo significance of p38 and HO-1 as mediators of EPO's cardioprotection was investigated in mice subjected to myocardial I/R. Pretreatment with EPO decreased infarct size as well as I/R-induced apoptosis in wild-type mice. However, these effects were significantly diminished in HO-1 Ϫ/Ϫ mice. Furthermore, EPO given during ischemia reduced infarct size in mice subjected to I/R, and this effect was blocked by CrMP treatment in wild-type mice. Moreover, inhibition of p38 diminished the cardioprotective effects of EPO. We conclude that upregulation of HO-1 expression via p38 signaling contributes to EPO-mediated cardioprotection during myocardial I/R. myocyte; apoptosis; myocardial infarction; p38 ERYTHROPOIETIN (EPO) has been shown to protect the heart from ischemia-reperfusion (I/R) injury (8, 11). After myocardial infarction, EPO improves cardiac function and reduces ventricular remodeling (41). Our laboratory has demonstrated an important role of protein kinase B (Akt) and endothelial nitric oxide (NO) synthase (eNOS)-derived NO production in the antiapoptotic effects of EPO during myocardial I/R (7). However, since EPO is known to activate multiple intracellular signaling pathways, it is possible that additional mechanisms are involved in EPO's cardioprotective effects.Heme oxygenase (HO) is the rate-limiting enzyme responsible for the breakdown of heme into free ferrous iron, carbon monoxide (CO), and biliverdin, which is ultimately converted to bilirubin. There are three known isoforms of HO. HO-1 is expressed ubiquitously and is inducible. HO-2 is constitutively active and expressed primarily in the brain and testes, and HO-3 is constitutively active as well, but less efficient than the other two oxygenases (47). HO-1 and its byproducts play an important role in regulating cardiomyocyte survival. To this end, the cardiac-specific overexpression of HO-1 reduces oxidative stress and cell death in the heart after myocardial I/R (49). Additionally, HO-1 is known to have a protective ...

Erythropoietin protects against hemorrhagic blood–brain barrier disruption through the effects of aquaporin-4

“…This implies that upregulation of AQP4 by EPO binding to EPOR may result from activation of JNK and p38-MAPK signal transduction pathways, which are known to be activated by EPO. [34][35][36] Several previous studies reported that a p38-MAPK inhibitor suppressed AQP4 upregulation induced by manganese treatment or hyperosmotic solutions. 16,17 Moreover, our recent study reveals that the JNK pathway was involved in VEGF's effect on AQP4 upregulation.…”

Molecular Basis of Cardioprotection

“…152 The stromal cell-derived factor-1α activates chemokine receptor 4 and reduces IS on exogenous administration, 153 and stromal cell-derived factor-1α is causally involved in IS reduction by RIPC. 154 Exogenous erythropoietin reduces IS when given before ischemia, 155 but also when given before reperfusion 156,157 with involvement of phosphatidylinositol (4,5)-bisphosphate 3-kinase (PI3K), ERK, p38, and heme oxy genase, but there is no evidence that erythropoietin is causally involved in the conditioning phenomena.…”

Endogenous Adenosine Selectively Modulates Oxidant Stressviathe A1Receptor in Ischemic Hearts

“…protective responses may harness HO-1 (1,5,63). We find that I=R rapidly induces HO-1 mRNA and tissue activity (within 45 min), an effect exaggerated by A 1 AR deletion (Fig.…”