ATP5A1 adenovirus

Under pathological conditions such as ischemia, diabetes, and sepsis, the protein levels and activities of calpain-1 and calpain-2 in cardiac mitochondria are increased, and transgenic overexpression of mitochondria-targeted calpain-1 induces dilated heart failure, highlighting the important role of increased mitochondrial calpains in mediating myocardial injury. Here, researchers generated transgenic mice that overexpressed mitochondria-targeted calpain inhibitors in cardiomyocytes. Transgenic overexpression of mitochondria-targeted calpain inhibitors significantly attenuated global ischemia/reperfusion-induced mitochondrial oxidative stress and cell death in isolated hearts and ameliorated mitochondrial oxidative stress, cell death, myocardial remodeling, and dysfunction in STZ-treated transgenic mice. The protective effects of mitochondria-targeted calpain inhibitors were associated with increased ATP5A1 protein expression and ATP synthase activity in isolated hearts subjected to global ischemia/reperfusion and in hearts of transgenic mice treated with STZ. In cultured rat myoblast H9c2 cells, overexpression of mitochondria-targeted calpain inhibitors maintained ATP5A1 protein levels and ATP synthase activity, prevented mitochondrial ROS generation, and reduced cell death after hypoxia/reoxygenation, whereas upregulation of ATP5A1 or scavenging of mitochondrial ROS by mito-TEMPO abolished mitochondrial ROS generation and reduced cell death. These results confirm the role of calpains in myocardial injury and suggest that selective inhibition of calpains in myocardial mitochondria by mitochondria-targeted calpain inhibitors is an effective strategy to mitigate myocardial injury and dysfunction in cardiac pathology.

Here, researchers determined whether overexpression of ATP5A1 would reduce mitochondrial ROS production and prevent cardiomyocyte death after H/R. H9c2 cells were infected with adenoviral vectors containing ATP5A1 (Ad-ATP5A1) or Ad-gal for 24 h, followed by 24 h of hypoxia and 24 h of reoxygenation (H/R). H/R induced an increase in mitochondrial ROS production in H9c2 cells, which was attenuated by infection with adenoviral vectors expressing ATP5A1 (Figure 1a, b). Overexpression of ATP5A1 reduced apoptosis as determined by caspase-3 activity (Figure 1c) and DNA fragmentation (Figure 1d), inhibited LDH release (Figure 1e), and increased viability of H9c2 cells after H/R (Figure 1f). Thus, overexpression of ATP5A1 reduced mitochondrial ROS production and H/R-induced cardiomyocyte death.

Figure 1. Effects of ATP5A1 overexpression in H9c2 cells following H/R. (Zheng D, et al., 2021)