Targeting Dynamin 2 as a Novel Pathway to Inhibit Cardiomyocyte Apoptosis Following Oxidative Stress.

BACKGROUND/AIMS Inhibition of Drp-1-mediated mitochondrial fission limits reactive oxygen species (ROS) production and apoptosis in cardiomyocytes subjected to ischemia/reperfusion injury. It remains unknown if Dynamin 2 inhibition results in similar protective effects. Here we studied the role of Dynamin 2 in cardiomyocyte oxidative stress-induced apoptosis and ROS production. METHODS The effect of lentiviral shRNA (lv5-shRNA) mediated Dynamin 2 knockdown on apopotosis, mitochondria, and ROS production were studied in neonatal mouse cardiomycytes, which were further treated with either selective Drp1 inhibitor mdivi-1 or the Dynamin 2/Drp1 inhibitor Dynasore. Apoptosis was evaluated by flow cytometry. Mitochondrial morphology and transmembrane potential (ΔΨm) were studied by confocal microscopy, and ROS production was detected by dichlorofluorescein diacetate. RESULTS Inhibition of Drp1 and Dynamin 2 protected against mitochondrial fragmentation, maintained ΔΨm, attenuated cellular ROS production and limited apoptosis. Moreover, Lv5-shRNA mediated knockdown of Dynamin 2 alleviated mitochondrial fragmentation, and reduced both ROS production and oxidative stress-induced apoptosis. The protective effects of Dynamin 2 knockdown were enhanced by Dynasore, indicating an added benefit. CONCLUSIONS Oxidative stress-induced apoptosis and ROS production are attenuated by not only Drp1 inhibition but also Dynamin 2 inhibition, implicating Dynamin 2 as a mediator of oxidative stress in cardiomyocytes.