Abstract 14145: The Zinc Transporter ZIP7 Plays a Critical Role in Ferrotposis Induced by Ischemia/Reperfusion in Mouse Hearts

Abstract

Background: Although ferroptosis has been proposed to play a role in myocardial ischemia/reperfusion (I/R) injury, the exact molecular mechanism by which ferroptosis is induced by I/R remains unclear. Hypothesis: We tested the hypothesis that upregulation of the zinc transporter ZIP7 at reperfusion triggers ferroptosis by downregulating the mitochondrial GPX4 (mtGPX4) via the guanine-rich sequence-binding factor 1 (GRSF1) and increasing mitochondrial iron accumulation through inhibition of the mitochondrial iron importer degradation. Aims: To determine if ZIP7 plays a role in I/R-induced ferroptosis and to investigate the underlying molecular mechanism. Methods: Mouse hearts were subjected to I/R in vivo . The cardiac-specific Slc39a7 conditional knockout mice (ZIP7 cKO) were generated by adopting the CRISPR/Cas9 system. Adult mouse cardiomyocytes were isolated enzymatically. Ferroptosis was evaluated by detecting PTGS2, MDA, and BODIPY C11. Mitochondrial Fe 2+ was determined with Mito-FerroGreen fluorescent probe. Results: I/R upregulated ZIP7 expression and induced ferroptosis as indicated by the increases in PTGS2 mRNA expression (290.90 ± 52.78 % of control), MDA (152.10 ± 15.07 % of control) and BODIPY C11 (130.68 ± 5.52 % of control) levels, which was prevented by ZIP7 cKO. ZIP7 cKO also mitigated doxorubicin-induced ferroptosis. ZIP7 cKO upregulated mtGPX4 expression (123.40±3.26 % of I/R) and increased mitochondrial GRSF1 expression (150.90±8.51 % of I/R) at reperfusion. In addition, knockout of GRSF1 inhibited GPX4 expression (54.73±5.44 % of control). Moreover, ZIP7 cKO prevented the accumulation of Fe 2+ within mitochondria (44.15±2.46 % of I/R) and promoted the degradation of SLC25A37 (62.57±8.03% of I/R) and SLC25A28 (69.82±3.10 % of I/R) at reperfusion. Conclusions: Upregulation of ZIP7 contributes to the induction of ferroptosis at reperfusion presumably by reducing mtGPX4 expression via GRSF1and increasing Fe 2+ accumulation within mitochondria through inhibition of SLC25A37 and SLC25A28 degradation.