Mitochondrial GPX4 acetylation is involved in cadmium-induced renal cell ferroptosis.

Increasing evidences demonstrate that environmental stressors are important inducers of acute kidney injury (AKI). This study aimed to investigate the impact of exposure to Cd, an environmental stressor, on renal cell ferroptosis. Transcriptomics analyses showed that arachidonic acid (ARA) metabolic pathway was disrupted in Cd-exposed mouse kidneys. Targeted metabolomics showed that renal oxidized ARA metabolites were increased in Cd-exposed mice. Renal 4-HNE, MDA, and ACSL4, were upregulated in Cd-exposed mouse kidneys. Consistent with animal experiments, the in vitro experiments showed that mitochondrial oxidized lipids were elevated in Cd-exposed HK-2 cells. Ultrastructure showed mitochondrial membrane rupture in Cd-exposed mouse kidneys. Mitochondrial cristae were accordingly reduced in Cd-exposed mouse kidneys. Mitochondrial SIRT3, an NAD+-dependent deacetylase that regulates mitochondrial protein stability, was reduced in Cd-exposed mouse kidneys. Subsequently, mitochondrial GPX4 acetylation was elevated and mitochondrial GPX4 protein was reduced in Cd-exposed mouse kidneys. Interestingly, Cd-induced mitochondrial GPX4 acetylation and renal cell ferroptosis were exacerbated in Sirt3-/- mice. Conversely, Cd-induced mitochondrial oxidized lipids were attenuated in nicotinamide mononucleotide (NMN)-pretreated HK-2 cells. Moreover, Cd-evoked mitochondrial GPX4 acetylation and renal cell ferroptosis were alleviated in NMN-pretreated mouse kidneys. These results suggest that mitochondrial GPX4 acetylation, probably caused by SIRT3 downregulation, is involved in Cd-evoked renal cell ferroptosis.

Arsenic exposure causes decline in sperm motility accompanied by energy metabolism disorders in mouse testes.

Arsenic (As) is a notorious environmental toxicant widely present in various natural environments. As exposure has been correlated with the decline in sperm motility. Yet, the mechanism has not been fully elucidated. Adult male C57 mice were given 0, 1, or 15 mg/L NaAsO2 for 10 weeks. The mature seminiferous tubules and sperm count were decreased in As-exposed mice. Sperm motility and several sperm motility parameters, including average path velocity (VAP), straight-line velocity (VSL), curvilinear velocity (VCL), beat-cross frequency (BCF), linearity (LIN), straightness (STR), and amplitude of lateral head displacement (ALH), were declined in As-exposed mice. RNA sequencing and transcriptomics analyses revealed that differentially expressed genes (DEGs) were mainly enriched in metabolic pathways. Untargeted metabolomics analyses indicated that energy metabolism was disrupted in As-exposed mouse testes. Gene set enrichment analysis showed that glycolysis and oxidative phosphorylation were disturbed in As-exposed mouse testes. As-induced disruption of testicular glucose metabolism and oxidative phosphorylation was further validated by RT-PCR and Western blotting. In conclusion, As exposure causes decline in sperm motility accompanied by energy metabolism disorders in mouse testes.

Mitochondria-derived reactive oxygen species are involved in renal cell ferroptosis during lipopolysaccharide-induced acute kidney injury.

Our earlier studies indicated that reactive oxygen species (ROS) were involved in lipopolysaccharide (LPS)-induced acute kidney injury (AKI). The present study aimed to explore the role of mitochondria-derived ROS on renal cell ferroptosis during LPS-induced AKI. Male CD-1 mice were intraperitoneally injected with LPS (2.0 mg/kg). Renal MDA and 4HNE residue, two markers of lipid peroxidation, were increased in LPS-exposed mice. Oxidized lipids were detected in LPS-treated human HK-2 cells. In vivo, ferroptosis-characteristic ultrastructure changes, including cell volume reduction, nuclear pyknosis and smaller mitochondria, were shown in renal cortex. In vitro, abnormal alteration of mitochondrial membrane potential was observed in LPS-treated human HK-2 cells. Ferrostatin-1, a specific inhibitor of ferroptosis, attenuated LPS-evoked renal lipid peroxidation, ferroptosis-characteristic mitochondrial damage and renal cell death. Mechanistically, mitochondria-derived ROS were elevated in LPS-stimulated HK-2 cells. MitoQ, a mitochondria-targeted antioxidant, almost completely scavenged LPS-stimulated mitochondrial ROS in human HK-2 cells. Moreover, pretreatment with MitoQ attenuated LPS-induced GSH depletion and lipid peroxidation in mouse kidney. Finally, pretreatment with MitoQ alleviated LPS-induced renal cell death and AKI. Taken together, these results suggest that mitochondria-derived ROS contribute, at least partially, to renal cell ferroptosis during LPS-induced AKI. Mitochondria-targeted antioxidants may be potential therapeutic agents for sepsis-induced AKI.