The activated ATM/AMPK/mTOR axis promotes autophagy in response to oxidative stress-mediated DNA damage co-induced by molybdenum and cadmium in duck testes

Environmentally relevant levels of Cd and Mo coexposure induces ferroptosis and excess ferritinophagy through AMPK/mTOR axis in duck myocardium

Cadmium (Cd) and excess molybdenum (Mo) are multiorgan toxic, but the detrimental impacts of Cd and/or Mo on poultry have not been fully clarified. Thence, a 16-week sub-chronic toxic experiment was executed with ducks to assess the toxicity of Cd and/or Mo. Our data substantiated that Cd and Mo coexposure evidently reduced GSH-Px, GSH, T-SOD, and CAT activities and elevated H2O2 and MDA concentrations in myocardium. What is more, the study suggested that Cd and Mo united exposure synergistically elevated Fe2+ content in myocardium and activated AMPK/mTOR axis, then induced ferroptosis by obviously upregulating ACSL4, PTGS2, and TFRC expression levels and downregulating SLC7A11, GPX4, FPN1, FTL1, and FTH1 expression levels. Additionally, Cd and Mo coexposure further caused excessive ferritinophagy by observably increasing autophagosomes, the colocalization of endogenous FTH1 and LC3, ATG5, ATG7, LC3II/LC3I, NCOA4, and FTH1 expression levels. In brief, this study for the first time substantiated that Cd and Mo united exposure synergistically induced ferroptosis and excess ferritinophagy by AMPK/mTOR axis, finally augmenting myocardium injure in ducks, which will offer an additional view on united toxicity between two heavy metals on poultry.

Irradiated tumour cell-derived microparticles upregulate MHC-I expression in cancer cells via DNA double-strand break repair pathway

Radiotherapy (RT) is used for over 50 % of cancer patients and can promote adaptive immunity against tumour antigens. However, the underlying mechanisms remain unclear. Here, we discovered that RT induces the release of irradiated tumour cell-derived microparticles (RT-MPs), which significantly upregulate MHC-I expression on the membranes of non-irradiated cells, enhancing the recognition and killing of these cells by T cells. Mechanistically, RT-MPs induce DNA double-strand breaks (DSB) in tumour cells, activating the ATM/ATR/CHK1-mediated DNA repair signalling pathway, and upregulating MHC-I expression. Inhibition of ATM/ATR/CHK1 reversed RT-MP-induced upregulation of MHC-I. Furthermore, phosphorylation of STAT1/3 following the activation of ATM/ATR/CHK1 is indispensable for the DSB-dependent upregulation of MHC-I. Therefore, our findings reveal the role of RT-MP-induced DSBs and the subsequent DNA repair signalling pathway in MHC-I expression and provide mechanistic insights into the regulation of MHC-I expression after DSBs.

Copper toxicity in the liver of broiler chicken: insights from metabolomics and AMPK-mTOR mediated autophagy perspective

Exposure to copper (Cu) has been associated with metabolic disorders in animals and humans, but the underlying mechanism remains unclear. One-day-old broiler chickens, numbering a total of 192, were nourished with dietary intakes that contained varying concentrations of Cu, specifically 11, 110, 220, and 330 mg/kg of Cu, for a period extending over a duration of 7 wk. As a result of the study, Cu exposure resulted in vacuolization, fragmentation of mitochondria cristae, and the increase of autophagosomes in hepatocytes. Metabolomics analysis illustrated that Cu caused a total of 59 different metabolites in liver, predominantly associated with the glycerophospholipid metabolic pathway, leading to metabolic disruption. Moreover, high-Cu diet markedly reduced the levels of AMPKα1, p-AMPKα1, mTOR, and p-mTOR and enhanced the expression levels of the autophagy-related factors (Atg5, Dynein, Beclin1, and LC3-II). Overall, Cu exposure caused chicken liver injury and resulted in disturbed metabolic processes and mediated autophagy primarily through the AMPK-mTOR axis.

Molybdenum and cadmium co-induce apoptosis and ferroptosis through inhibiting Nrf2 signaling pathway in duck (Anas platyrhyncha) testes

Cadmium (Cd) and high molybdenum (Mo) are injurious to the body. Previous research has substantiated that Cd and Mo exposure caused testicular injury of ducks, but concrete mechanism is not fully clarified. To further survey the toxicity of co-exposure to Cd and Mo in testis, 40 healthy 8-day-old Shaoxing ducks (Anas platyrhyncha) were stochasticly distributed to 4 groups and raised with basic diet embracing Cd (4 mg/kg Cd) or Mo (100 mg/kg Mo) or both. At the 16th wk, testis tissues were gathered. The characteristic ultrastructural changes related to apoptosis and ferroptosis were observed in Mo or Cd or both groups. Besides, Mo or Cd or both repressed nuclear factor erythroid 2-related factor 2 (Nrf2) pathway via decreasing Nrf2, Heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), Glutamate-cysteine ligase catalytic subunit (GCLC) and Glutamate-cysteine ligase modifier subunit (GCLM) mRNA expression of and Nrf2 protein expression, then stimulated apoptosis by elevating Bcl-2 antagonist/killer-1 (Bak-1), Bcl-2-associated X-protein (Bax), Cytochrome complex (Cyt-C), caspase-3 mRNA expression, cleaved-caspase-3 protein expression and apoptosis rate, as well as reducing B-cell lymphoma-2 (Bcl-2) mRNA expression and ratio of Bcl-2 to Bax, and triggered ferroptosis by upregulating Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), transferrin receptor (TFR1) and Prostaglandin-Endoperoxide Synthase 2 (PTGS2) expression levels, and downregulating ferritin heavy chain 1 (FTH1), ferritin light chain 1 (FTL1), ferroportin 1 (FPN1), solute carrier family 7 member 11 (SCL7A11) and glutathione peroxidase 4 (GPX4) expression levels. The most obvious changes of these indexes were observed in co-treated group. Altogether, the results announced that Mo or Cd or both evoked apoptosis and ferroptosis by inhibiting Nrf2 pathway in the testis of ducks, and co-exposure to Mo and Cd exacerbated these variations.

Luteolin Alleviates Cadmium-Induced Kidney Injury by Inhibiting Oxidative DNA Damage and Repairing Autophagic Flux Blockade in Chickens

Chickens are a major source of meat and eggs in human food and have significant economic value. Cadmium (Cd) is a common environmental pollutant that can contaminate feed and drinking water, leading to kidney injury in livestock and poultry, primarily by inducing the generation of free radicals. It is necessary to develop potential medicines to prevent and treat Cd-induced nephrotoxicity in poultry. Luteolin (Lut) is a natural flavonoid compound mainly extracted from peanut shells and has a variety of biological functions to defend against oxidative damage. In this study, we aimed to demonstrate whether Lut can alleviate kidney injury under Cd exposure and elucidate the underlying molecular mechanisms. Renal histopathology and cell morphology were observed. The indicators of renal function, oxidative stress, DNA damage and repair, NAD+ content, SIRT1 activity, and autophagy were analyzed. In vitro data showed that Cd exposure increased ROS levels and induced oxidative DNA damage and repair, as indicated by increased 8-OHdG content, increased γ-H2AX protein expression, and the over-activation of the DNA repair enzyme PARP-1. Cd exposure decreased NAD+ content and SIRT1 activity and increased LC3 II, ATG5, and particularly p62 protein expression. In addition, Cd-induced oxidative DNA damage resulted in PARP-1 over-activation, reduced SIRT1 activity, and autophagic flux blockade, as evidenced by reactive oxygen species scavenger NAC application. The inhibition of PARP-1 activation with the pharmacological inhibitor PJ34 restored NAD+ content and SIRT1 activity. The activation of SIRT1 with the pharmacological activator RSV reversed Cd-induced autophagic flux blockade and cell injury. In vivo data demonstrated that Cd treatment caused the microstructural disruption of renal tissues, reduced creatinine, and urea nitrogen clearance, raised MDA content, and decreased the activities or contents of antioxidants (GSH, T-SOD, CAT, and T-AOC). Cd treatment caused oxidative DNA damage and PARP-1 activation, decreased NAD+ content, decreased SIRT1 activity, and impaired autophagic flux. Notably, the dietary Lut supplement observably alleviated these alterations in chicken kidney tissues induced by Cd. In conclusion, the dietary Lut supplement alleviated Cd-induced chicken kidney injury through its potent antioxidant properties by relieving the oxidative DNA damage-activated PARP-1-mediated reduction in SIRT1 activity and repairing autophagic flux blockade.

Rat Hepatocytes Protect against Lead-Cadmium-Triggered Apoptosis Based on Autophagy Activation

Lead and cadmium are foodborne contaminants that threaten human and animal health. It is well known that lead and cadmium produce hepatotoxicity; however, defense mechanisms against the co-toxic effects of lead and cadmium remain unknown. We investigated the mechanism of autophagy (defense mechanism) against the co-induced toxicity of lead and cadmium in rat hepatocytes (BRL-3A cells). Cultured rat liver BRL-3A cell lines were co-cultured with 10, 20, 40 μM lead and 2.5, 5, 10 μM cadmium alone and in co-culture for 12 h and exposed to 5 mM 3-Methyladenine (3-MA), 10 μM rapamycin (Rapa), and 50 nM Beclin1 siRNA to induce cellular autophagy. Our results show that treatment of BRL-3A cells with lead and cadmium significantly decreased the cell viability, increased intracellular reactive oxygen species levels, decreased mitochondrial membrane potential levels, and induced apoptosis, which are factors leading to liver injury, and cell damage was exacerbated by co-exposure to lead-cadmium. In addition, the results showed that lead and cadmium co-treatment induced autophagy. We further observed that the suppression of autophagy with 3-MA or Beclin1 siRNA promoted lead-cadmium-induced apoptosis, whereas enhancement of autophagy with Rapa suppressed lead-cadmium-induced apoptosis. These results demonstrated that co-treatment with lead and cadmium induces apoptosis in BRL-3A cells. Interestingly, the activation of autophagy provides cells with a self-protective mechanism against induced apoptosis. This study provides insights into the role of autophagy in lead-cadmium-induced apoptosis, which may be beneficial for the treatment of lead-cadmium-induced liver injury.

Molybdenum exposure induces inflammatory response via the regulatory effects of lncRNA-00072124/miR-308/OSMR crosstalk on JAK/STAT axis in duck kidneys

Molybdenum (Mo) is an essential nutrient in living organisms. Although numerous researchers have noticed the health damage caused by excessive Mo, the underlying mechanism of excessive Mo-induced nephrotoxicity remains poorly understood. A gene crosstalk called competitive endogenous RNAs (ceRNAs) can interpret many regulatory mechanisms molecularly. But there are few researches have tried to explain the damage mechanism of excess Mo to organisms through ceRNAs network. To clarify this, the study explored the changes in lncRNAs and miRNAs expression profiles in the kidney of ducks exposed to excess Mo for 16 weeks. The sequencing results showed that Mo exposure caused differential expression of 144 lncRNAs and 14 miRNAs. The occurrence of inflammation through the JAK/STAT axis was observed and the lncRNA-00072124/miR-308/OSMR axis was verified by a double luciferase reporter assay. Overexpression of miR-308 and RNA interference of OSMR reduced Mo-induced inflammatory factors, while miR-308 knockdown showed the opposite effect. Simultaneously, lncRNA-00072124 affected OSMR function as a ceRNA. Taken together, these results concluded that Mo exposure activated the JAK/STAT axis and induced inflammation mediated by the lncRNA-00072124/miR-308/OSMR crosstalk. The results might provide new views for revealing the toxic effects of excess Mo in duck kidneys.

Activation of moderate autophagy promotes survival of fat graft

Clinically unpredictable retention following fat grafting remains outstanding problems because of the unrevealed mechanism of grafted fat survival. The role of autophagy, a process to maintain cellular homeostasis through recycling cellular debris, has yet been to be reported in fat grafting. This study aims to improve the survival of fat grafting through the autophagy. First, the relationship between cell death and autophagy in the early stage of fat grafting was evaluated through immunostaining, RNA sequencing, and western blot. Next, rapamycin, an autophagic agonist, was used for the culturing of adipose-derived stem cells and adipocytes during ischemia. Cell death, autophagy, and reactive oxygen species (ROS) were assayed. Finally, rapamycin was used to assist fat grafting in nude mice. The results demonstrated that the peak of cell death at the early stage of fat grafting was accompanied by a decrease in autophagy. In vitro, during ischemia, 25 nM was confirmed as the optimal dose of rapamycin that reduces cell death with enhanced autophagy and mitophagy, improved mitochondrial quality as well as decreased ROS accumulation. In vivo, promoted mitophagy, alleviated oxidative stress, and decreased cell apoptosis of rapamycin-treated fat grafts were observed in the early stage. In addition, rapamycin increased the survival of fat grafts with increased neovascularization and reduced fibrosis. We suggested that moderate autophagy induced by rapamycin contribute to enhanced ischemic tolerance and long term survival of fat grafts through mitochondrial quality control.

Co-exposure to molybdenum and cadmium evokes necroptosis and decreases apoptosis in duck myocardium

Superfluous molybdenum (Mo) and cadmium (Cd) in the environment are detrimental to organisms through their accumulation. The NF-κB/TNF-α axis plays a vital part in regulating necroptosis and apoptosis. However, the impacts of Mo and/or Cd on myocardium injury in ducks and the function of NF-κB/TNF-α axis are not clear in the process. In this research, ducks exposed to different dosages of Mo and/or Cd were applied as the study object. The findings substantiated that the accumulation of Mo and/or Cd caused elements imbalance and necroptosis in myocardial tissue. As p-NF-κB/TNF-α expression up-regulated, RIPK1/RIPK3/p-MLKL expression significantly increased in all treatment groups, while the expression of c-caspase-8/3 markedly decreased. Moreover, apoptosis rate obviously decreased in Cd treated groups and clearly elevated in Mo group. Mitochondria-mediated apoptosis was activated by excessive Mo and inhibited by Mo + Cd, but Cd exposure alone had little effect on it. Collectively, our research confirmed that Mo and/or Cd evoked necroptosis via NF-κB/TNF-α axis, and decreased death receptor-mediated apoptosis in duck myocardium, the impacts of Mo and/or Cd on mitochondrial-mediated apoptosis were different. These results are significant for studying toxicology of Mo and/or Cd and preserving the ecosystem.

SMYD3 Modulates AMPK-mTOR Signaling Balance in Cancer Cell Response to DNA Damage

Cells respond to DNA damage by activating a complex array of signaling networks, which include the AMPK and mTOR pathways. After DNA double-strand breakage, ATM, a core component of the DNA repair system, activates the AMPK-TSC2 pathway, leading to the inhibition of the mTOR cascade. Recently, we showed that both AMPK and mTOR interact with SMYD3, a methyltransferase involved in DNA damage response. In this study, through extensive molecular characterization of gastrointestinal and breast cancer cells, we found that SMYD3 is part of a multiprotein complex that is involved in DNA damage response and also comprises AMPK and mTOR. In particular, upon exposure to the double-strand break-inducing agent neocarzinostatin, SMYD3 pharmacological inhibition suppressed AMPK cascade activation and thereby promoted the mTOR pathway, which reveals the central role played by SMYD3 in the modulation of AMPK-mTOR signaling balance during cancer cell response to DNA double-strand breaks. Moreover, we found that SMYD3 can methylate AMPK at the evolutionarily conserved residues Lys411 and Lys424. Overall, our data revealed that SMYD3 can act as a bridge between the AMPK and mTOR pathways upon neocarzinostatin-induced DNA damage in gastrointestinal and breast cancer cells.

Low dosage fluorine ameliorates the bioaccumulation, hepatorenal dysfunction and oxidative stress, and gut microbiota perturbation of cadmium in rats

Many "hot spot" geographic areas around the world with soils and crops co-polluted with cadmium (Cd) and fluorine (F), two of the most representative pollutants in the environment. However, it still exists argumentative on the dose-effect relationship between F and Cd so far. To explore this, a rat model was established to evaluate the effects of F on Cd-mediated bioaccumulation, hepatorenal dysfunction and oxidative stress, and the disorder of intestinal microbiota as well. 30 healthy rats were randomly assigned to Control group (C group), Cd 1 mg/kg (Cd group), Cd 1 mg/kg and F 15 mg/kg (L group), Cd 1 mg/kg and F 45 mg/kg (M group), and Cd 1 mg/kg and F 75 mg/kg (H group) for 12 weeks by gavage. Our results showed that Cd exposure could accumulate in organs, cause hepatorenal function damage and oxidative stress, and disorder of gut microflora. However, different dosages of F showed various effects on Cd-induced damages in liver, kidney, and intestine, and only the low supplement of F showed a consistent trend. After low supplement of F, Cd levels were declined by 31.29% for liver, 18.31% for kidney, and 2.89% for colon, respectively. The serum aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (Cr), and N-acetyl-β-glucosaminidase (NAG) were significantly reduced (p < 0.01); The activity of superoxide dismutase (SOD) was elevated and mRNA expression level of NAD(P)H quinone oxidoreductase 1 (NQO1) was decreased in the liver and kidney (p < 0.05). Moreover, low F dosage up-regulated the abundance of Lactobacillus from 15.56% to 28.73% and the 6.23% of F/B ratio was declined to 3.70%. Collectively, this highlights that low dosage of F might be a potential strategy to ameliorate the hazardous effects by Cd-exposed in the environment.