The zinc transporter ZIP7 controls cardiac ferroptosis by targeting mitochondria in the setting of ischemia/reperfusion

AIMS: While ferroptosis is demonstrated to be involved in myocardial ischemia/reperfusion (I/R) injury, the detailed mechanism is yet to be fully elucidated. Since the zinc transporter ZIP7 (Slc39a7) contributes to myocardial I/R injury by targeting mitochondria and inhibition of ZIP7 attenuates erastin-induced cell death, we hypothesized that upregulation of ZIP7 induces ferroptosis by targeting mitochondria in mouse hearts subjected to I/R. METHODS AND RESULTS: Mouse hearts or cardiomyocytes were subjected to I/R or hypoxia/reoxygenation (H/R). Doxorubicin (DOX) or I/R upregulated ZIP7and induced ferroptosis. DOX or I/R-induced ferroptosis and cardiac injury were attenuated by ZIP7 cKO (cardiac-specific conditional knockout). I/R resulted in downregulation of mitochondrial GPX4 (mtGPX4) and guanine-rich RNA sequence binding factor 1 (GRSF1) in a ZIP7 dependent manner. GRSF1 knockout (KO) or its shRNA inhibited mtGPX4 expression or activity, and the protective effect of ZIP7 cKO on I/R-induced ferroptosis and myocardial infarction was abolished by GRSF1 shRNA or ZIP7/mtGPX4 double knockout (DKO). Moreover, the mitochondrial iron importers SLC25A28 and SLC25A37 were upregulated by I/R, which was reversed by ZIP7 cKO. We further found that ZIP7 upregulates SLC25A28 and SLC25A37 by inhibiting PINK1-mediated mitophagy. In support, the protective effects of ZIP7 cKO on mitochondrial Fe2+ accumulation, ferroptosis, and cardiac injury were blocked by PINK1 siRNA or SLC25A37 siRNA. Finally, the anti-infarct effect of ZIP7 cKO was not improved by the ferroptosis inhibitor ferrostatin-1. CONCLUSIONS: ZIP7 upregulation triggers ferroptosis in I/R hearts through the antioxidant axis (GRSF1-mtGPX4) and the mitophagic axis (PINK1-SLC25A28/37). The inhibition of GRSF1 may lead to the downregulation of mtGPX4, whereas suppression of mitophagy may result in mitochondrial iron accumulation through the upregulation of SLC25A28 and SLC25A37.