MitomiR-504 alleviates the copper-induced mitochondria-mediated apoptosis by suppressing Bak1 expression in porcine jejunal epithelial cells.

Copper (Cu), an environmental heavy metal pollutant, has been widely researched in its toxicology. Recently, an increasing number of mitochondrial microRNAs (mitomiRs) have been shown to involve in the metabolic regulation. However, the underlying mechanisms of mitomiRs on regulating apoptosis under Cu exposure are still unclear. Here, we proved that Cu induced mitochondria-mediated apoptosis in porcine jejunal epithelial cells, concomitant with distinct reduction of mitomiR-504 in vivo and in vitro. The miR-504 mimic notably enhanced the mRNA and protein expressions of Bak1, Bax, Cleaved-caspase3 and Caspase-9, and significantly decreased the apoptosis rate and Bcl-2 mRNA and protein levels, indicating that overexpression of mitomiR-504 attenuated the Cu-induced mitochondria-mediated apoptosis. Besides, Bak1 was confirmed as a direct target of mitomiR-504 by the bioinformatics analysis and dual-luciferase reporter assay. Subsequently, transfection of siRNA targeting Bak1 significantly enhanced the alleviating effect of miR-504 mimic on the Cu-induced mitochondria-mediated apoptosis. Overall, these suggested that overexpression of mitomiR-504 alleviated the Cu-induced mitochondria-mediated apoptosis in jejunal epithelial cells by suppressing Bak1 expression. These findings are conducive to elucidating the mechanism of Cu-induced jejunal epithelial pathologies, providing a new research idea for the Cu toxicology.

NAC alleviative ferroptosis in diabetic nephropathy via maintaining mitochondrial redox homeostasis through activating SIRT3-SOD2/Gpx4 pathway.

Diabetic nephropathy (DN) is known as a major microvascular complication in type 1 diabetes. The effect of insulin treatment alone on controlling blood glucose is unsatisfactory. N-acetylcysteine (NAC), a chemical agent with thiol group, is found to confer a protective effect in renal injury. However, whether NAC combined with insulin treatment can further enhance the therapeutic effect in DN remains unclear. Here, we firstly used large mammal beagle as DN model to explore the effect of NAC combined with insulin treatment on DN during 120 d. Our results showed that NAC further alleviated mitochondrial oxidative damage and ferroptosis by enhancing activity of mitochondria GSH and maintaining mitochondrial redox homeostasis in DN. Additionally, the upregulated acetylation level of SOD2 was further abrogated by NAC treatment. In MDCK cells, NAC reduced high glucose (HG)-caused ferroptosis via activating Gpx4 expression. Of note, inhibition of Gpx4 by FIN56 abolished the protective effects of NAC on HG-induced ferroptosis. More importantly, 3-TYP reversed the effect of NAC on the mitochondria ROS under HG treatment, as well as eliminated its following beneficial effects for ferroptosis against HG-stimulated cells. These results reveal that NAC attenuated ferroptosis in DN via maintaining mitochondrial redox homeostasis through activating SIRT3-SOD2-Gpx4 signaling pathway.

Toxicological mechanism of large amount of copper supplementation: Effects on endoplasmic reticulum stress and mitochondria-mediated apoptosis by Nrf2/HO-1 pathway-induced oxidative stress in the porcine myocardium.

Copper (Cu) is an essential micronutrient that is required by all living organisms. However, Cu can also be a potentially toxic metal if excessive dietary supplementation occurs. The current study aimed to investigate the mechanism of Cu toxicity in the cardiomyocytes of large mammal pigs. Here, we used pigs to explore Cu toxicity in the control group (10 mg/kg Cu) and treatment groups (125 mg/kg and 250 mg/kg Cu) for a period of 80 days. Consequently, we identified that large amount intake of Cu led to in oxidative damage, and activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1)-mediated antioxidant pathway, indicating an imbalanced redox status in the myocardium. Furthermore, Cu exposure activated endoplasmic reticulum (ER) stress through upregulating levels of glucose-regulated protein 78 (GRP78), c-Jun N-terminal kinase (JNK), glucose-regulated protein 94 (GRP94), X-box binding protein 1 (XBP1), and C/EBP homologous protein (CHOP). Additionally, mitochondrial fission and fusion homeostasis was disrupted and the copy number of mitochondrial DNA (mtDNA) was reduced under Cu exposure. Furthermore, Cu exposure could induce apoptosis, evidenced by the increased terminal deoxynucleotidyl transferase biotin-d UTP nick end labeling (TUNEL)-positive staining, the upregulated expression levels of Cytoplasm-cytochrome C (Cytc), Bcl-2-associated X protein (Bax), and Cleaved-caspase3, and decreased expression level of B-cell lymphoma-2 (Bcl-2) and Mitochondrial-cytc. In summary, large amount of Cu could trigger Nrf2/HO-1 pathway-mediated oxidative stress, which promotes ER stress and mitochondrial damage pathways, causing apoptosis in cardiomyocytes.

Endoplasmic Reticulum Stress Contributes to Copper-Induced Pyroptosis via Regulating the IRE1α-XBP1 Pathway in Pig Jejunal Epithelial Cells.

Copper (Cu) is a common additive in food products, which poses a potential concern to animal and human health when it is in excess. Here, we investigated the relationship between endoplasmic reticulum (ER) stress and pyroptosis in Cu-induced toxicity of jejunum in vivo and in vitro. In in vivo experiments, excess intake of dietary Cu caused ER cavity expansion, elevated fluorescence signals of GRP78 and Caspase-1, and increased the mRNA and protein expression levels related to ER stress and pyroptosis in pig jejunal epithelium. Simultaneously, similar effects were observed in IPEC-J2 cells under excess Cu treatment. Importantly, 4-phenylbutyric acid (ER stress inhibitor) and MKC-3946 (IRE1α inhibitor) significantly inhibited the ER stress-triggered IRE1α-XBP1 pathway, which also alleviated the Cu-induced pyroptosis in IPEC-J2 cells. In general, these results suggested that ER stress participated in regulating Cu-induced pyroptosis in jejunal epithelial cells via the IRE1α-XBP1 pathway, which provided a novel view into the toxicology of Cu.

Feasibility of using ammonium iron (II) sulphate to passivate hexavalent chromium in polluted soil.

ABSTRACTThe use of ammonium iron (II) sulphate ((NH4)2Fe(SO4)2) to remediate soil contaminated with Cr (VI) was assessed. (NH4)2Fe(SO4)2 effectively remediated soil contaminated with Cr (VI) and, acted as a fertilizer by supplying nitrogen because it contains ammonium. The effects of the (NH4)2Fe(SO4)2 dose, water content, pH of the soil and the contact time were investigated. The amount of Cr (VI) leached from the most-polluted soil, determined using a leaching toxicity procedure using optimized conditions, was 347.64 mg kg-1 when the soil was untreated and 6.74 mg kg-1 when the soil was treated with (NH4)2Fe(SO4)2. Bio-utilizable Cr contributed 59.44% and 0.16% of the total Cr contents of the untreated and treated soil, respectively. The relatively stable Cr species contributed 24.92% and 98.38% of the total Cr contents of the untreated and treated soil, respectively. The results indicated that adding (NH4)2Fe(SO4)2 markedly decreased the risk of Cr being released from heavily contaminated soil by decreasing the availability of Cr in the soil. Overall, the results indicated that adding (NH4)2Fe(SO4)2 causes some Cr (VI) in contaminated soil to be reduced to Cr (III), and to form a precipitate, which decreases the risk of Cr being released. (NH4)2Fe(SO4)2 can be applied to soil contaminated with Cr (VI) on a large scale because it is cheap and simple to achieve.

Mitochondrial miR-1285 regulates copper-induced mitochondrial dysfunction and mitophagy by impairing IDH2 in pig jejunal epithelial cells.

Copper (Cu), a hazardous heavy metal, can lead to toxic effects on host physiology. Recently, specific mitochondria-localized miRNAs (mitomiRs) were shown to modulate mitochondrial function, but the underlying mechanisms remain undefined. Here, we identified mitomiR-1285 as an important molecule regulating mitochondrial dysfunction and mitophagy in jejunal epithelial cells under Cu exposure. Mitochondrial dysfunction and mitophagy were the important mechanisms of Cu-induced pathological damage in jejunal epithelial cells, which were accompanied by significant increase of mitomiR-1285 in vivo and in vitro. Knockdown of mitomiR-1285 significantly attenuated Cu-induced mitochondrial respiratory dysfunction, ATP deficiency, mitochondrial membrane potential reduction, mitochondrial reactive oxygen species accumulation, and mitophagy. Subsequently, bioinformatics analysis and luciferase reporter assay demonstrated that IDH2 was a direct target of mitomiR-1285. RNA interference of IDH2 dramatically reversed the effect that mitomiR-1285 knockdown relieved mitochondrial dysfunction and mitophagy induced by Cu, and the opposite effect was shown by overexpression of IDH2. Therefore, our results suggested that mitomiR-1285 aggravated Cu-induced mitochondrial dysfunction and mitophagy via suppressing IDH2 expression. These findings identified the important mechanistic connection between mitomiRs and mitochondrial metabolism under Cu exposure, providing a new insight into Cu toxicology.