SYVN1/GPX5 axis affects ischemia/reperfusion induced apoptosis of AC16 cells by regulating ROS generation.

Ischemia/reperfusion (I/R) induced injury is a major cause of coronary heart disease (CHD). Increased production of reactive oxygen species (ROS) can lead to an I/R injury in CHD, and the ROS level can be regulated by Glutathione peroxidase (GPX) enzyme family. In this study, we investigated the role and underlying molecular mechanism of GPX5 in I/R-induced AC16 cells. We found that the serum level of GPX5 was down-regulated in patients with CHD and I/R-induced AC16 cells. Overexpression of GPX5 inhibited I/R-induced apoptosis by suppressing the production of ROS. On the other hand, knock-down of GPX5 promoted apoptosis in AC16 cells by up-regulating the level of ROS. Furthermore, we found that GPX5 was regulated by synovial apoptosis inhibitor 1 (SYVN1)-mediated ubiquitination in AC16 cells. In I/R-induced AC16 cells, the expression of SYVN1 was up-regulated, and SYVN1 knock-down decreased the ROS levels and apoptotic rate but increased GPX5 levels. Moreover, GPX5 knockdown promoted ROS production and apoptosis, while its effects were attenuated by SYVN1 knockdown. Furthermore, SYVN1 was up-regulated while GPX5 was down-regulated in the myocardial tissue of I/R-injured rats. Taken together, our data demonstrate that GPX5 inhibits I/R-induced apoptosis of AC16 cells by down-regulating ROS level, and its stabilization is regulated by SYVN1-mediated ubiquitination.