Mitochondrial glutaredoxin-2 (Glrx2) has been recognized as an important redox regulator in mammalian organs including heart. To date no investigations have addressed the potential role of Glrx2 in
cardiac disorders. The present study examined if myocardial overexpression of Glrx2 in the heart could rescue the cardiac cells from apoptosis and
necrosis induced by
ischemia and reperfusion. The human Glrx2 transgene was created by placing a full-length
cDNA fragment encoding human mitochondrial Glrx2 downstream to the 5' flanking sequence and promoter of the mouse
alpha-myosin heavy chain gene. The isolated hearts from Glrx2 transgenic mice and non-transgenic (wild type) littermates [on c57BL/6xC3H hybrid background] were subjected to 30 min of global
ischemia followed by 2 h of reperfusion via working mode. The hearts from Glrx2 transgenic mice displayed significantly improved contractile performance and reduced
myocardial infarct size and cardiomyocyte apoptosis. There was a reduction in
cytochrome c release and activation of
caspase 3 and
caspase 9. Glrx2 overexpression also reduced the
ischemia/reperfusion-mediated loss of mitochondrial
cardiolipin, decreased the activities of
reactive oxygen species (ROS) and preserved GSH/
GSSG ratio. Glrx2 mediated survival signal appeared to be stemmed from PI-3-kinase-Akt survival signaling pathway and involved the activation of redox sensitive
transcription factor NFkappaB and antiapoptotic
protein Bcl-2. The results indicated a crucial role of mitochondrial Glrx2 in cardioprotection.