Cardioprotective potential of transcription factor PRRX1 silencing against myocardial ischemia/reperfusion injury by regulating excessive mitophagy and ferroptosis through FKBP5-p38 MAPK axis

Myocardial ischemia/reperfusion (I/R) injury is a major cause of various adverse cardiovascular outcomes associated with excessive mitophagy and cardiomyocyte ferroptosis. Paired-related homeobox 1 (PRRX1) is a transcriptional factor involved in cardiovascular injury. However, whether and how PRRX1 regulates excessive mitophagy and cardiomyocyte ferroptosis during myocardial I/R injury remains unclear. Oxygen-glucose deprivation and reperfusion (OGD/R)-treated AC16 cardiomyocytes and myocardial I/R-induced rats were used as in vitro and in vivo models. Our results showed that PRRX1 expression was upregulated in AC16 cells after OGD/R treatment. PRRX1 silencing mitigated OGD/R-induced excessive mitophagy by increasing the mitochondrial membrane potential, adenosine triphosphate and p62 levels, and reducing LC3 II/I level in AC16 cells. In addition, PRRX1 knockdown attenuated OGD/R-induced lactate dehydrogenase (LDH) release and cardiomyocyte ferroptosis by decreasing reactive oxygen species, Fe2+ and acyl-CoA synthetase long-chain family member 4 (ACSL4) levels, and increasing glutathione (GSH) and glutathione peroxidase 4 (GPX4) levels. Furthermore, PRRX1 transcriptionally promoted FK506 binding protein 5 (FKBP5), and increased p38 MAPK activation in AC16 cells. FKBP5 overexpression reversed the effects of PRRX1 silencing on excessive mitophagy and cardiomyocyte ferroptosis in OGD/R-treated AC16 cells. These effects were mitigated by a p38 MAPK inhibitor. Finally, PRRX1 downregulation mitigated myocardial I/R injury by reducing heart infarction and creatine kinase-myocardial band (CK-MB) levels in rat models. These findings demonstrate that PRRX1 silencing attenuates OGD/R-induced excessive mitophagy and cardiomyocyte ferroptosis by decreasing FKBP5 expression and inactivating p38 MAPK signaling, indicating the cardioprotective potential of PRRX1 silencing in myocardial I/R injury.