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Hexavalent chromium (Cr(VI)) is a hazardous substance that poses significant risks to environmental ecosystems and animal organisms. However, the specific consequences of Cr(VI) exposure in terms of liver damage remain incompletely understood. This study aims to elucidate the mechanism by which Cr(VI) disrupts mitochondrial dynamics, leading to hepatic injury in ducks. Forty-eight healthy 8-day-old ducks were divided into four groups and subjected to diets containing varying doses of Cr(VI) (0, 9.28, 46.4, and 232 mg/kg) for 49 days. Our results demonstrated that Cr(VI) exposure resulted in disarranged liver lobular vacuolation, along with increasing the serum levels of ALT, AST, and AKP in a dose-dependent manner, which indicated liver damage. Furthermore, Cr(VI) exposure induced oxidative stress by reducing the activities of T-SOD, SOD, GSH-Px, GSH, and CAT, while increasing the contents of MDA and H 2 O 2 . Moreover, Cr(VI) exposure downregulated the activities of CS and MDH, resulting in energy disturbance, as evidenced by the reduced AMPK/p-AMPK ratio and PGC-1α protein expression. Additionally, Cr(VI) exposure disrupted mitochondrial dynamics through decreased expression of OPA1, Mfn1, and Mfn2 and increased expression of Drp-1, Fis1, and MFF proteins. This disruption ultimately triggered mitochondria-mediated apoptosis, as evidenced by elevated levels of caspase-3, Cyt C, and Bax, along with decreased expression of Bcl-2 and the Bcl-2/Bax ratio, at both the protein and mRNA levels. In summary, this study highlights that Cr(VI) exposure induces oxidative stress, inhibits the AMPK-PGC-1α pathway, disrupts mitochondrial dynamics, and triggers liver cell apoptosis in ducks.

The accumulation of copper (Cu) in the organisms could lead to kidney damage by causing mitochondrial dysfunction. Given that mitochondria are one of the targets of Cu poisoning, this study aimed to investigate the role of mitophagy in Cu-induced mitochondrial dysfunction in renal tubular epithelial cells to understand the mechanism of Cu nephrotoxicity. Hence, the cells were treated with different concentrations of Cu sulfate (CuSO 4 ) (0, 100, and 200 μM), and mitophagy inhibitor (Cyclosporine A, 0.5 μM) and/or 200 μM CuSO 4 in the combination for 12 h. Results showed that Cu caused mitochondrial swelling, vacuoles, and cristae fracture; increased the number of mitochondrial and lysosome fluorescent aggregation points; upregulated the mRNA levels of mitophagy-associated genes (LC3A, LC3B, P62, BNIP3, NIX, OPTN, NDP52, Cyp D LAMP1, and LAMP2) and protein levels of LC3II/LC3I, BNIP3, and NIX, downregulated the mRNA and protein levels of P62; reduced the mitochondrial membrane potential (MMP), ATP content, mitochondrial respiratory control rate (RCR), mitochondrial respiratory control rate (OPR), and the mRNA and protein levels of PGC-1α, TOMM20, and Mfn2, but increased the mRNA and protein levels of Drp1. Besides, cotreatment with Cu and CsA dramatically decreased the level of mitophagy, but increased mitochondrial division, further reduced MMP, ATP content, RCR, and OPR, mitochondrial fusion and thereby reduced mitochondrial biogenesis. Taken together, these data indicated that Cu exposure induced BNIP3/NIX-dependent mitophagy in duck renal tubular epithelial cells, and inhibition of mitophagy aggravated Cu-induced mitochondrial dysfunction., (© 2022 Wiley Periodicals LLC.)

Copper (Cu) as a transition metal can be toxic to public and ecosystem health at high level, but the specific mechanism of Cu-evoked nephrotoxicity remains elusive. Here, we first revealed the crosstalk between mitofusin2 (Mfn2)-dependent mitochondria-associated endoplasmic reticulum membrane (MAM) dynamics and autophagy in duck renal tubular epithelial cells under Cu exposure. Primary duck renal tubular epithelial cells were treated with 100 and 200 μM Cu sulfate for 12 h and exposed to lentivirus to deliver mitofusin2 (Mfn2). We found that excessive Cu disrupted MAM integrity, decreased the mitochondrial calcium level, co-localization of IP3R and VDAC1, the mRNA levels of PACS2, Mfn2, IP3R and MCU, and Mfn2 and VDAC1 protein levels, causing MAM dysfunction. Furthermore, Mfn2 overexpression ameliorated Cu-induced MAM dysfunction, and increased Cu-evoked autophagy in duck renal tubular epithelial cells accompanied with the elevation of autophagosomes number, ROS level, LC3 puncta, Atg5 and LC3B mRNA levels, and Beclin1, Atg14, LC3BII/LC3BI protein levels. Accordingly, our data proved that excessive Cu could trigger MAM dysfunction and autophagy in duck renal tubular epithelial cells, and Cu-induced autophagy could be activated through Mfn2-dependent MAM, providing evidence on the toxicological exploration mechanisms of Cu., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Copper (Cu) is a vital micronutrient required for numerous fundamental biological processes, but excessive Cu poses potential detrimental effects on public and ecosystem health. However, the molecular details linking endoplasmic reticulum (ER) stress and apoptosis in duck renal tubular epithelial cells have not been fully elucidated. In this study, duck renal tubular epithelial cells exposed to Cu sulfate (CuSO 4 ) (0, 100 and 200 μM) and a PERK inhibitor (GSK2606414, GSK, 1 μM) for 12 h were used to investigate the crosstalk between ER stress and apoptosis under Cu exposure. Cell and ER morphological and functional characteristics, intracellular calcium (Ca 2+ ) levels, apoptotic rates, ER stress and apoptosis-related mRNA and protein levels were examined. The results showed that excessive Cu could cause ER expansion and swelling, increase the expression levels of ER stress-associated genes (PERK, eIF2α, ATF4 and CHOP) and proteins (p-PERK and CHOP), induce intracellular Ca 2+ overload, upregulate the expression levels of apoptosis-associated genes (Bax, Bak1, Caspase9 and Caspase3) and the cleaved-Caspase3 protein, downregulate Bcl-xl and Bcl2 mRNA levels and trigger apoptosis. PERK inhibitor treatment could ameliorate the above changed factors caused by Cu. In conclusion, these findings indicate that excessive Cu could trigger ER stress via activation of the PERK/ATF4/CHOP signaling pathway and that ER stress might aggravate Cu-induced apoptosis in duck renal tubular epithelial cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The aim of this study was to investigate the crosstalk between oxidative stress and autophagy through the ROS/HO-1/NQO1 pathway caused by copper (Cu). Duck renal tubular epithelial cells were treated in Cu sulfate (CuSO 4 ) (0, 100 and 200 μM) for 12 h, and in the combination of CuSO 4 (200 μM) and reactive oxygen species (ROS) scavenger (butyl hydroxyanisole, BHA, 100 μM), or HO-1 inhibitor (zinc protoporphyrin, ZnPP, 10 μM) for 12 h. Results revealed that Cu could significantly elevate the levels of intracellular ROS, superoxide dismutase, hydrogen peroxide, malondialdehyde, glutathione, simultaneously reduce catalase and glutathione peroxidase levels, and upregulate HO-1, SOD-1, CAT, NQO1, GCLM mRNA levels and HO-1, SOD-1 protein levels. Additionally, Cu could observably increase the number of autophagosomes, acidic vesicle organelles (AVOs) and LC3 puncta; upregulate mRNA levels of mTOR, Beclin-1, ATG7, ATG5, ATG3, LC3II and protein levels of Beclin-1, LC3II/LC3I, downregulate LC3I mRNA level. Both treatments with BHA and ZnPP could significantly alleviate the changes of antioxidant indexes levels and ROS accumulation, reduce the increase of the number of autophagosomes, AVOs and LC3 puncta, and mitigate the above changed oxidative stress and autophagy related mRNA and protein levels induced by Cu. In summary, our findings indicated that excessive Cu could induce oxidative stress and autophagy by activating the ROS/HO-1/NQO1 pathway, and inhibition of HO-1 might attenuate Cu-induced oxidative stress and autophagy in duck renal tubular epithelial cells., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Cadmium (Cd) and high Molybdenum (Mo) can lead to adverse reactions on animals, but the co-induced toxicity of Mo and Cd to liver in ducks was not well understood. To investigate the co-induced toxic effects of Mo combined with Cd on mitochondrial oxidative stress and apoptosis in duck livers. 240 healthy 11-day-old ducks were randomly divided into 6 groups (control, LMo group, HMo group, Cd group, LMoCd group and HMoCd group). After being treated for 30, 60, 90 and 120 days, liver mitochondrial antioxidant indexes, ceruloplasmin (CP), metallothionein (MT), Bak-1 and Caspase-3 genes mRNA expression levels, and ultrastructural changes were evaluated. The results showed that total antioxidative capacity (T-AOC), catalase (CAT), superoxide dismutase (SOD) and xanthine oxidase (XOD) activities in experimental groups were decreased, whereas malondialdehyde (MDA) content and nitric oxide synthase (NOS) activity were increased compared with control group, and these changes of co-treated groups were more obvious in the later period of the experiment. The mRNA expression levels of CP, Bak-1 and Caspase-3 were up-regulated in experimental groups compared with control group and showed significant difference between co-treated groups and single treated groups. The mRNA expression level of MT in Cd group was higher than that in co-treated groups. Additionally, ultrastructural changes showed karyopyknosis, mitochondrial swelling, vacuolation and disruption of mitochondrial cristae in co-treated groups. Taken together, it was suggested that dietary Mo and Cd might lead to mitochondrial oxidative stress and apoptosis in duck livers, and it showed a possible synergistic relationship between the two elements., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The aims of this study were determining the co-induced effects of dietary Cadmium (Cd) and high intake of Molybdenum (Mo) on renal toxicity in ducks. 240 healthy 11-day-old ducks were randomly divided into 6 groups, which were treated with Mo or/and Cd at different doses added to the basal diet for 120 days. Ducks of control group were fed with basal diet, LMo and HMo groups were fed with 15mg/kg Mo and 100mg/kg Mo respectively; ducks of Cd group were provided with 4mg/kg Cd which was added into basal diet. Two combination groups were treated with 15mg/kg Mo+4mg/kg Cd and 100mg/kg Mo+4mg/kg Cd respectively. On days 30, 60, 90 and 120, the mRNA expression levels of inflammatory cytokines and contents of trace elements were detected. In addition, transmission electron microscopic examination was used for ultrastructural studies. The results indicated that the mRNA expression levels of tumor necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), and cyclooxygenase-2 (COX-2) showed an upward tendency in treatment groups in comparison with control group, and in the later period of the experiment it showed a significant rise in joint groups compared with the Mo and Cd group (P<0.01); the contents of copper (Cu) and iron (Fe) decreased in joint groups in the later period (P<0.05) while the contents of Mo and Cd significantly increased (P<0.01); zinc (Zn) and selenium (Se) concentration had a slight downtrend in treated groups, but showed no significant difference (P>0.05). The ultrastructural analysis showed that kidney tissues were severely injured in joint groups on day 120. These results suggested that the combination of Mo and Cd could aggravate damages to the kidney. In addition, dietary of Mo or/and Cd caused the decrease of Cu, Fe, Zn, and Se contents, inflammatory response and pathological lesions whose mechanism is somehow linked with Mo and Cd deposition in kidney., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Molybdenum (Mo) is an essential element for human beings and animals; however, high dietary intake of Mo can lead to adverse reactions. Cadmium (Cd) is harmful to health. To investigate the toxicity of Mo combined with Cd in duck kidneys, 240 ducks were randomly divided into six groups and treated with a commercial diet containing Mo, Cd or Mo combined with Cd. Kidneys were collected on days 30, 60, 90 and 120 for determining the expression of heat shock proteins (HSPs), including HSP60, HSP70 and HSP90 in the kidney through quantitative RT-PCR. We also determined the antioxidant activity indexes in the kidney mitochondria. Moreover, kidney tissues at 120 days were subjected to histopathological analysis with the optical microscope. The results indicated that the expression of HSPs was highly significantly (P < 0.01) upregulated in the kidneys of the combination groups and the Cd group. Exposure to Cd and a high dose of Mo decreased the total antioxidative capacity and the activity of xanthine oxidase, while malondialdehyde levels and the activity of nitric oxide synthase increased compared with those of the control groups in the kidney mitochondria. This was particularly evident at 90 and 120 days. Histopathological lesions included congestion and bleeding in the renal interstitium, swelling of the distal convoluted tubule epithelial cells, granular degeneration and blister degeneration in the renal tubular epithelial cells. These results suggest that a combination of Mo and Cd leads to greater tissue damage and has a synergistic effect on kidney damage. Oxidative damage of kidney mitochondria may be a potential nephrotoxicity mechanism of molybdenum and cadmium, and the high expression of HSPs may play a role in the resistance of kidney toxicity induced by Mo and Cd.

Cadmium (Cd) is an occupational and environmental pollutant, which mainly causes nephrotoxicity by damaging renal proximal tubular cells. To evaluate the effects of Cd on pyroptosis and the relationship between pyroptosis and apoptosis in duck renal tubular epithelial cells, the cells were cultured with 3CdSO 4 ·8H 2 O (0, 2.5, 5.0, or 10.0 μM Cd), N-acetyl-L-cysteine (NAC) (100.0 μM), Z-YVAD-FMK (10.0 μM) or the combination of Cd and NAC or Z-YVAD-FMK for 12 h, and then cytotoxicity was assessed. The results evidenced that Cd significantly increased the releases of interleukin-18 (IL-18) and interleukin-1β (IL-1β), lactate dehydrogenase (LDH) and nitric oxide (NO), relative conductivity and cellular reactive oxygen species (ROS) level. Simultaneously, Cd also markedly upregulated NLRP3, Caspase-1, ASC, NEK7, IL-1β and IL-18 mRNA levels and NLRP3, Caspase-1 p20, GSDMD and ASC protein levels. Additionally, NAC notably improved the changes of above indicators induced by Cd. Combined treatment with Cd and Z-YVAD-FMK remarkably elevated Bcl-2 mRNA and protein levels, inhibited p53, Bax, Bak-1, Cyt C, Caspase-9 and Caspase-3 mRNA levels and p53, Bax, Bak-1, Caspase-9/cleaved Caspase-9 and Caspase-3/cleaved Caspase-3 protein levels, increased mitochondrial membrane potential (MMP), decreased apoptosis ratio and cell damage compared to treatment with Cd alone. Taken together, Cd exposure induces duck renal tubular epithelial cell pyroptosis through ROS/NLRP3/Caspase-1 signaling pathway, and inhibiting Caspase-1 dependent pyroptosis attenuates Cd-induced apoptosis. Image 1 • Cadmium (Cd) toxicity was evaluated in duck renal tubular epithelial cells. • Cd could induce pyroptosis via ROS/NLRP3/Caspase-1 pathway. • N-acetyl-L-cysteine (NAC) could inhibit pyroptosis induced by Cd. • Inhibiting Caspase-1-dependent pyroptosis might weaken Cd induced-apoptosis. [ABSTRACT FROM AUTHOR]