Abstract
The aim of this study is to examine the role of thioredoxin-2 (Trx2) in autophagy and apoptosis during myocardial ischemia-reperfusion (I/R) injury in vitro. We employed the oxygen-glucose deprivation and reperfusion (OGD/R) model of H9c2 cells and used lentiviral infection to overexpress Trx2. H9c2 cell viability and injury assays were conducted using a Cell Counting Kit-8 (CCK-8) and alactate dehydrogenase (LDH) kit. The effects of Trx2 on autophagy and apoptosis were measured by transmission electron microscopy (TEM), western blot, and flow cytometry. Our results showed that the expression of Trx2 was significantly decreased at reperfusion 6 h after OGD 12 h treatment. Trx2 overexpression inhibited autophagy in H9c2 cells subjected to OGD/R. As the underlying mechanisms, both Akt kinase/the mammalian target of rapamycin (Akt/mTOR) and AMP-activated protein kinase (AMPK)/mTOR signaling pathways were involved in the regulation of Trx2 during autophagy, which was also mediated by reactive oxygen species (ROS). 3-methyladenine (3-MA), an inhibitor of autophagy, not only suppressed OGD/R-induced autophagy but also decreased apoptosis. As a classical autophagy sensitizer, rapamycin (Rapa) augmented autophagy as well as apoptosis. Additionally, we further demonstrated that Trx2 could alleviate OGD/R-induced apoptosis via mitochondrion-mediated intrinsic apoptotic pathway. In summary, our data indicated that Trx2 protects cardiomyocytes under OGD/R by inhibiting autophagy and apoptosis. Trx2 may be a crucial regulatory protein during I/R-induced cardiomyocyte injury and death.