PINK1/Parkin-mediated mitophagy is involved in NaAsO2-induced apoptosis of human hepatic cells through activation of ERK signaling

The mitochondria-targeted antioxidant MitoQ ameliorates inorganic arsenic-induced DCs/Th1/Th2/Th17/Treg differentiation partially by activating PINK1-mediated mitophagy in murine liver

Inorganic arsenic is a well-established environmental toxicant linked to acute liver injury, fibrosis, and cancer. While oxidative stress, pyroptosis, and ferroptosis are known contributors, the role of PTEN-induced kinase 1 (PINK1)-mediated mitophagy in arsenic-induced hepatic immunotoxicity remains underexplored. Our study revealed that acute arsenic exposure prompts differentiation of hepatic dendritic cells (DCs) and T helper (Th) 1, Th2, Th17, and regulatory T (Treg) cells, alongside increased transcription factors and cytokines. Inorganic arsenic triggered liver redox imbalance, leading to elevated alanine transaminase (ALT), hydrogen peroxide (H2O2), malondialdehyde (MDA), and activation of nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1) pathway. PINK1-mediated mitophagy was initiated, and its inhibition exacerbates H2O2 accumulation while promoting DCs/Th1/Th2/Treg differentiation in the liver of arsenic-exposed mice. Mitoquinone (MitoQ) pretreatment relieved arsenic-induced acute liver injury and immune imbalance by activating Nrf2/HO-1 and PINK1-mediated mitophagy. To our knowledge, this is the first report identifying PINK1-mediated mitophagy as a protective factor against inorganic arsenic-induced hepatic DCs/Th1/Th2 differentiation. This study has provided new insights on the immunotoxicity of inorganic arsenic and established a foundation for exploring preventive and therapeutic strategies targeting PINK1-mediated mitophagy in acute liver injury. Consequently, the application of mitochondrial antioxidant MitoQ may offer a promising treatment for the metalloid-induced acute liver injury.

Study on the mechanism of arsenic-induced renal injury based on SWATH proteomics technology

BACKGROUND

Arsenic (As) poisoning is a worldwide endemic disease affecting thousands of people. As is excreted mainly through the renal system, and arsenic has toxic effects on the kidneys, but the mechanism has not been elucidated. In this study, the molecular basis of arsenic's nephrotoxicity was studied by using a high-throughput proteomics technique.

METHODS

Eight SD (Sprague-Dawley) rats, half male and half female, were fed an As diet containing 50 mg/kg NaAsO2. Age- and sex-matched rats fed with regular chow were used as controls. At the end of the experiment (90 days), kidney tissue samples were collected and assessed for pathological changes using hematoxylin-eosin staining. Proteomic methods were used to identify alterations in protein expression levels in kidney tissues, and bioinformatic analyses of differentially expressed proteins between arsenic-treated and control groups were performed. The expression of some representative proteins was validated by Western blot analysis.

RESULTS

NaAsO2 could induce renal injury. Compared with the control group, 112 proteins were up-regulated, and 46 proteins were down-regulated in the arsenic-treated group. These proteins were associated with the electron transport chain, oxidative phosphorylation, mitochondrial membrane, apoptosis, and proximal tubules, suggesting that the mechanisms associated with them were related to arsenic-induced kidney injury and nephrotoxicity. The expressions of Atp6v1f, Cycs and Ndufs1 were verified, consistent with the results of omics.

CONCLUSION

These results provide important evidence for arsenic-induced kidney injury and provide new insights into the molecular mechanism of arsenic-induced kidney injury.

The mechanism of nickel-induced autophagy and its role in nephrotoxicity

Nickel (Ni), an environmental health hazard, is nephrotoxic to humans, but the exact mechanism is unknown. This study aims to identify whether nephrotoxicity is associated with autophagy. Here, nickel chloride (NiCl2) increased autophagy in TCMK-1 cells. NiCl2 induces autophagy through Akt and AMPK/mTOR pathways. Next, oxidative stress was investigated in NiCl2-induced autophagy. The findings demonstrated that the antioxidant (NAC) or mitochondrial targeted antioxidant (Mito-TEMPO) attenuated NiCl2-induced autophagy, reversed the influence on AMPK-mTOR and Akt pathways. Additionally, our study examined the role of autophagy in NiCl2-induced nephrotoxicity. Autophagy inhibition with 3-MA could inhibit cell viability and increase apoptosis in the TCMK-1 cells, however, autophagy promotion with rapamycin relieved cytotoxicity and decreased apoptosis. Additionally, co-treatment with Z-VAD-FMK reduced cytotoxicity, but did not affect autophagy. Besides, NiCl2 can increase the level of mitophagy in vivo and vitro. Mitophagy inhibition could inhibit cell viability and increase apoptosis in the TCMK-1 cells, whereas, promotion of mitophagy could increase cell viability and decrease apoptosis. In summary, above-mentioned results showed that NiCl2 induces autophagy in TCMK-1 cells through oxidative stress-dependent AMPK/AKT-mTOR pathway, autophagy plays a role in reducing NiCl2-induced renal toxicity, and a major mechanism in autophagy's inhibitory effect on NiCl2-induced apoptosis may be mitophagy.

The interplay of mitophagy, autophagy, and apoptosis in cisplatin-induced kidney injury: involvement of ERK signaling pathway

AKI induced by CP chemotherapy remains an obstacle during patient treatments. Extracellular signal-regulated protein kinases 1/2 (ERK), key participants in CP-induced nephrotoxicity, are suggested to be involved in the regulation of mitophagy, autophagy, and apoptosis. Human renal proximal tubular cells (HK-2) and BALB/cN mice were used to determine the role of ERK in CP-induced AKI. We found that active ERK is involved in cell viability reduction during apoptotic events but exerts a protective role in the early stages of treatment. Activation of ERK acts as a maintainer of the mitochondrial population and is implicated in mitophagy initiation but has no significant role in its conduction. In the late stages of CP treatment when ATP is deprived, general autophagy that requires ERK activation is initiated as a response, in addition to apoptosis activation. Furthermore, activation of ERK is responsible for the decrease in reserve respiratory capacity and controls glycolysis regulation during CP treatment. Additionally, we found that ERK activation is also required for the induction of NOXA gene and protein expression as well as FoxO3a nuclear translocation, but not for the regular ERK-induced phosphorylation of FoxO3a on Ser294. In summary, this study gives detailed insight into the involvement of ERK activation and its impact on key cellular processes at different time points during CP-induced kidney injury. Inhibitors of ERK activation, including Mirdametinib, are important in the development of new therapeutic strategies for the treatment of AKI in patients receiving CP chemotherapy.

Assessing the double-edged of extracellular signal-regulated kinase/CCAAT-enhancer-binding protein beta signaling pathway in arsenic-induced skin damage and its potential foodborne interventions

Arsenic exposure is a major environmental public health challenge worldwide. As typical manifestations for arsenic exposure, the pathogenesis of arsenic-induced skin lesions has not been fully elucidated, as well as the lack of effective control measures. In this study, we first determined the short-term and high-dose arsenic exposure can increase the apoptosis rates, while long-term low-dose arsenic exposure decrease the apoptosis rates. Then, the HaCaT cells with knockdown and overexpression of CCAAT-enhancer-binding protein β (CEBPB) and extracellular signal-regulated kinase (ERK) were constructed. The results demonstrate that knockdown of CEBPB and ERK can reduce NaAsO2 -induced cell apoptosis by inhibiting ERK/CEBPB signaling pathway and vice versa. Further cells were treated with Kaji-Ichigoside F1 (KF1). The results clearly show that KF1 can decrease the arsenic-induced cell apoptosis rates and the expression of ERK/CEBPB signaling pathway-related genes. These results provide evidence that ERK/CEBPB signaling pathway acts as a double-edged sword in arsenic-induced skin damage. Another interesting finding was that KF1 can alleviate arsenic-induced skin cell apoptosis by inhibiting the ERK/CEBPB signaling pathway. This study will contribute to a deeper understanding of the mechanisms of arsenic-induced skin cell apoptosis, and our findings will help to identify a potential food-borne intervention in arsenic detoxification.

Arsenic Exposure-Induced Acute Kidney Injury by Regulating SIRT1/PINK1/Mitophagy Axis in Mice and in HK-2 Cells

Groundwater resources are often contaminated by arsenic, which poses a serious threat to human and animal's health. Some studies have demonstrated that acute arsenic exposure could induce kidney injury because the kidney is a key target organ for toxicity, but the exact mechanism remains unclear. Hence, we investigated the effect of SIRT1-/PINK1-mediated mitophagy on NaAsO2-induced kidney injury in vivo and in vitro. In our study, NaAsO2 exposure obviously induced renal tubule injury and mitochondrial dysfunction. Meanwhile, NaAsO2 exposure could inhibit the mRNA/protein level of SIRT1 and activate the mitophagy-related mRNA/protein levels in the kidney of mice. In HK-2 cells, we also confirmed that NaAsO2-induced nephrotoxicity depended on the activation of mitophagy. Moreover, the activation of SIRT1 by resveratrol alleviated NaAsO2-induced acute kidney injury via the activation of mitophagy in vivo and in vitro. Interestingly, the inhibition of mitophagy by cyclosporin A (CsA) further exacerbated NaAsO2-induced nephrotoxicity and inflammation in HK-2 cells. Taken together, our study found that SIRT1-regulated PINK1-/Parkin-dependent mitophagy was implicated in NaAsO2-induced acute kidney injury. In addition, we confirmed that PINK1-/Parkin-dependent mitophagy played a protective role against NaAsO2-induced acute kidney injury. Therefore, activation of SIRT1 and mitophagy may represent a novel therapeutic target for the prevention and treatment of NaAsO2-induced acute renal injury.

Assessing the potential molecular mechanism of arsenite-induced skin cell senescence

Arsenic exposure is a public health concern worldwide. Skin damage, as a typical lesion of arsenic exposure, the mechanism is still unknown. Studies have found that cellular senescence plays a key role in arsenic-induced skin damage, and the previous research found that the ERK/CEBPB signaling pathway may be an important molecular event of arsenic-induced skin cell senescence, but its specific mechanism is unknown. In this study, genetic engineering technology was used to construct stable HaCaT cell lines, and the role and mechanism of ERK/CEBPB signaling pathway in arsenic-induced HaCaT cell senescence were verified by knockdown and overexpression of ERK and CEBPB in both forward and backward. It was found that knockdown of CEBPB or ERK can downregulate the ERK/CEBPB signaling pathway and reduce arsenic-induced skin cell senescence. In contrast to knockdown, overexpression of CEBPB or ERK can upregulate the ERK/CEBPB signaling pathway and aggravate the senescence of skin cells caused by arsenic. These findings suggest that sodium arsenite can further promote SASP secretion and the expression of p53, p21 and p16 INK4a by activating the ERK/CEBPB signaling pathway, induce cell cycle arrest and trigger cellular senescence.

Mitochondrial Oxidative Stress Is the General Reason for Apoptosis Induced by Different-Valence Heavy Metals in Cells and Mitochondria

This review analyzes the causes and consequences of apoptosis resulting from oxidative stress that occurs in mitochondria and cells exposed to the toxic effects of different-valence heavy metals (Ag+, Tl+, Hg2+, Cd2+, Pb2+, Al3+, Ga3+, In3+, As3+, Sb3+, Cr6+, and U6+). The problems of the relationship between the integration of these toxic metals into molecular mechanisms with the subsequent development of pathophysiological processes and the appearance of diseases caused by the accumulation of these metals in the body are also addressed in this review. Such apoptosis is characterized by a reduction in cell viability, the activation of caspase-3 and caspase-9, the expression of pro-apoptotic genes (Bax and Bcl-2), and the activation of protein kinases (ERK, JNK, p53, and p38) by mitogens. Moreover, the oxidative stress manifests as the mitochondrial permeability transition pore (MPTP) opening, mitochondrial swelling, an increase in the production of reactive oxygen species (ROS) and H2O2, lipid peroxidation, cytochrome c release, a decline in the inner mitochondrial membrane potential (ΔΨmito), a decrease in ATP synthesis, and reduced glutathione and oxygen consumption as well as cytoplasm and matrix calcium overload due to Ca2+ release from the endoplasmic reticulum (ER). The apoptosis and respiratory dysfunction induced by these metals are discussed regarding their interaction with cellular and mitochondrial thiol groups and Fe2+ metabolism disturbance. Similarities and differences in the toxic effects of Tl+ from those of other heavy metals under review are discussed. Similarities may be due to the increase in the cytoplasmic calcium concentration induced by Tl+ and these metals. One difference discussed is the failure to decrease Tl+ toxicity through metallothionein-dependent mechanisms. Another difference could be the decrease in reduced glutathione in the matrix due to the reversible oxidation of Tl+ to Tl3+ near the centers of ROS generation in the respiratory chain. The latter may explain why thallium toxicity to humans turned out to be higher than the toxicity of mercury, lead, cadmium, copper, and zinc.

Recent insights into autophagy and metals/nanoparticles exposure

Some anthropogenic pollutants, such as heavy metals and nanoparticles (NPs), are widely distributed and a major threat to environmental safety and public health. In particular, lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and mercury (Hg) have systemic toxicity even at extremely low concentrations, so they are listed as priority metals in relation to their significant public health burden. Aluminum (Al) is also toxic to multiple organs and is linked to Alzheimer's disease. As the utilization of many metal nanoparticles (MNPs) gradually gain traction in industrial and medical applications, they are increasingly being investigated to address potential toxicity by impairing certain biological barriers. The dominant toxic mechanism of these metals and MNPs is the induction of oxidative stress, which subsequently triggers lipid peroxidation, protein modification, and DNA damage. Notably, a growing body of research has revealed the linkage between dysregulated autophagy and some diseases, including neurodegenerative diseases and cancers. Among them, some metals or metal mixtures can act as environmental stimuli and disturb basal autophagic activity, which has an underlying adverse health effect. Some studies also revealed that specific autophagy inhibitors or activators could modify the abnormal autophagic flux attributed to continuous exposure to metals. In this review, we have gathered recent data about the contribution of the autophagy/mitophagy mediated toxic effects and focused on the involvement of some key regulatory factors of autophagic signaling during exposure to selected metals, metal mixtures, as well as MNPs in the real world. Besides this, we summarized the potential significance of interactions between autophagy and excessive reactive oxygen species (ROS)-mediated oxidative damage in the regulation of cell survival response to metals/NPs. A critical view is given on the application of autophagy activators/inhibitors to modulate the systematic toxicity of various metals/MNPs.

Hepatorenal Toxicity of Inorganic Arsenic in White Pekin Ducks and Its Amelioration by Using Ginger

The toxic metalloid arsenic is known to cause liver and kidney injury in many humans and animals. The goal of this paper was to exemplify the antagonism of ginger against arsenic (As)-induced hepato-renal toxicity. In addition, the pathways Nrf2/Keap1 and NF/κB were studied to reveal the molecular mechanism of the stress. One hundred twenty 7-day-old White Pekin ducks were randomly allocated into five groups, having 24 birds in each. Each group contained three replicates having 8 birds in each replicate and maintained for 90 days. The groups were as follows: T-1 [control-basal diet with normal water], T-2 [T1 + As at 28 ppm/L of water], T-3 [T2 + ginger powder at 100 mg/kg feed], T-4 [T2 + ginger powder at 300 mg/kg feed], and T-5 [T2 + ginger powder at 1 g/kg feed]. It was observed that there was a significant increase in oxidative parameters whereas a significant decrease in antioxidant parameters in hepato-renal tissues in T-2. The exposure to As not only decreased the mRNA expression of antioxidant parameters like Nrf2, SOD-1, CAT, GPX, and HO-1and anti-inflammatory markers like IL-4 and IL-10 but also increased the m-RNA expression of NF-κB, Keap-1 and pro-inflammatory markers like IL-2, Il-6, IL-18, IL-1β, and TNF-α. There was also an accumulation of As in hepatic and renal tissue, confirmed by residual analysis of these tissues. By correlating the above parameters, As at 28 ppm showed significant toxic effects, and ginger powder at 1 g/kg feed effectively counteracted the toxic effects of As in ducks.

PINK1/Parkin-mediated mitophagy modulates cadmium-induced apoptosis in rat cerebral cortical neurons

Cadmium is a persistent environmental pollutant whose neurotoxicity is of serious concern. Mitochondrial dysfunction and its mediated mitophagy and apoptosis are considered key events in Cd-induced neurological pathologies, but the exact molecular mechanism has not been fully elucidated. The aim of this study was to investigate the relationship between Cd-induced mitophagy and apoptosis and their role in Cd-induced neuronal death. Using the mitophagy inhibitor cyclosporine A (CsA), we found that the extent of mitophagy mediated by the PTEN-induced putative kinase protein 1 (PINK1)/E3 ubiquitin ligase (Parkin) pathway decreased, whereas the level of apoptosis and cell death increased in rat cerebral cortical neurons in vitro. Consistent with this, the knockdown of PINK1 also exacerbated Cd-induced apoptosis and neuronal death. Furthermore, the results of the in vivo experiments showed that Cd simultaneously activated both mitophagy and apoptosis and that the suppression of mitophagy by CsA aggravated Cd-induced apoptosis. In summary, our results indicate that PINK1/Parkin-mediated mitophagy exerts an important neuroprotective effect by inhibiting Cd-mediated apoptosis in rat cerebral cortical neurons both in vitro and in vivo. This work may allow the development of new therapeutic strategies for Cd-induced central nervous system disorders.

The regulatory role and mechanism of autophagy in energy metabolism-related hepatic fibrosis

Hepatic fibrosis is a key pathological process of chronic liver diseases, caused by alcohol, toxic and aberrant energy metabolism. It progresses to cirrhosis or even hepatic carcinoma without effective treatment. Studies have shown that autophagy has important regulatory effects on hepatic stellate cells (HSCs) energy metabolism, and then affect the activation state of HSCs. Autophagy maintains hepatic energy homeostasis, and the dysregulation of autophagy can lead to the activation of HSCs and the occurrence and development of hepatic fibrosis. It is necessary to explore the mechanism of autophagy in energy metabolism-related hepatic fibrosis. Herein, the current study summarizes the regulating mechanisms of autophagy through different targets and signal pathways in energy metabolism-related hepatic fibrosis, and discusses the regulatory effect of autophagy by natural plant-derived, endogenous and synthetic compounds for the treatment of hepatic fibrosis. A better comprehension of autophagy in hepatic stellate cells energy metabolism-related hepatic fibrosis may provide effective intervention of hepatic fibrosis, explore the potential clinical strategies and promote the drug treatment of hepatic fibrosis.

Inorganic arsenic promotes apoptosis of human immortal keratinocytes through the TGF-β1/ERK signaling pathway

Chronic exposure to high-dose inorganic arsenic through groundwater, air, or food remains a major environmental public health issue worldwide. Apoptosis, a method of cell death, has recently become a hot topic of research in biology and medicine. Previous studies have demonstrated that extracellular signal-regulated kinase (ERK) is related to arsenic-induced apoptosis. However, the reports are contradictory, and the knowledge of the above-mentioned mechanisms and their mutual regulation remains limited. In this study, the associations between the TGF-β1/ERK signaling pathway and arsenic-induced cell apoptosis were confirmed using the HaCaT cell model. The relative expressions of the indicators of the TGF-β1/ERK signaling pathway, apoptosis-related genes (cytochrome C, caspase-3, caspase-9, cleaved caspase-3, cleaved caspase-9, and Bax), the mitochondrial membrane potential, and the total apoptosis rate were significantly increased (P < .05), while the expression of the antiapoptosis gene Bcl-2 was significantly decreased (P < .05) in cells of the group exposed to arsenic. Moreover, the results demonstrated that the ERK inhibitor (PD98059) and TGF-β1 inhibitor (LY364947) could inhibit the activation of the ERK signaling pathway, thereby reducing the mitochondrial membrane potential, the total apoptosis rate, and the expression of pro-apoptosis-related genes in the cells, while the expression of the antiapoptosis gene Bcl-2 was significantly increased (P < .05). By contrast, the recombinant human TGF-β1 could promote apoptosis of the HaCaT cells by increasing the activation of the ERK signaling pathway (P < .05). These results indicate that inorganic arsenic promotes the apoptosis of human immortal keratinocytes through the TGF-β1/ERK signaling pathway.

Dictyophora Polysaccharide Attenuates As-Mediated PINK1/Parkin Pathway-Induced Mitophagy in L-02 Cell through Scavenging ROS

Arsenic (As) is common in the human living environment and a certain amount of exposure to As can lead to liver damage; this toxic effect has been proved to be closely related to intracellular PINK1/Parkin pathway-mediated mitophagy. Dictyophora is an edible fungus that extracts polysaccharides with antioxidant and hepatoprotective effects. In the present study, we demonstrated that As induced the onset of mitophagy in hepatocytes by stimulating cellular production of ROS to activate PINK1/Parkin, and the extent of damage increased with increased As-induced toxicity. Dictyophora polysaccharide (DIP) has the ability to scavenge intracellular ROS, which can inhibit oxidative stress injury and inhibit the PINK/Parkin pathway through its receptors or efficacious proteins, thus preventing mitochondrial autophagy and alleviating the hepatotoxicity of As. In conclusion, our results indicate that DIP can reduce As-induced PINK1/Parkin pathway-mediated hepatic mitophagy through scavenging ROS and exert hepatoprotective effects, providing experimental data and theoretical basis for the development of medicinal value of Dictyophora as a dual-use food and medicinal fungus.

The Molecular Mechanism of Hepatic Lipid Metabolism Disorder Caused by NaAsO2 through Regulating the ERK/PPAR Signaling Pathway

Chronic arsenic exposure is a risk factor for human fatty liver disease, and the ERK signaling pathway plays an important role in the regulation of liver lipid metabolism. However, whether ERK plays a role in the progression of arsenic-induced liver lipid metabolism disorder and the specific mechanism remain unclear. Here, by constructing a rat model of liver lipid metabolism disorder induced by chronic arsenic exposure, we demonstrated that ERK might regulate arsenic-induced liver lipid metabolism disorders through the PPAR signaling pathway. Arsenic could upregulate the expression of PPARγ and CD36 in the rat liver, decrease the expression of PPARα and CPT-1 in the rat liver, increase the organ coefficient of the rat liver, decrease the content of TG in rat serum, and promote fat deposition in the rat liver. In the arsenic-induced rat model of hepatic lipid metabolism disorder, we found that the expression of p-ERK was increased. In order to further explore whether the ERK signaling pathway was involved in arsenic-induced liver lipid metabolism disorder, we exposed L-02 cells to different arsenic concentrations, and the results showed that arsenic significantly increased the expression of P-ERK in L-02 cells in a dose-dependent manner. We further treated L-02 cells with ERK inhibitors and found that the expression of TG, PPARα, and CPT-1 in L-02 cells increased, while the expression of P-ERK, PPARγ, and CD36 decreased. In conclusion, ERK may be involved in arsenic-induced liver lipid metabolism disorder by regulating the PPAR signaling pathway. These findings are expected to provide a new targeting strategy for arsenic-induced liver lipid metabolism disorder.

Assessing the Potential Value and Mechanism of Kaji-Ichigoside F1 on Arsenite-Induced Skin Cell Senescence

Chronic exposure to inorganic arsenic is a major environmental public health issue worldwide affecting more than 220 million of people. Previous studies have shown the correlation between arsenic poisoning and cellular senescence; however, knowledge regarding the mechanism and effective prevention measures has not been fully studied. First, the associations among the ERK/CEBPB signaling pathway, oxidative stress, and arsenic-induced skin cell senescence were confirmed using the HaCaT cell model. In the arsenic-exposed group, the relative mRNA and protein expressions of ERK/CEBPB signaling pathway indicators (ERK1, ERK2, and CEBPB), cell cycle-related genes (p21, p16^INK4a), and the secretion of SASP (IL-1α, IL-6, IL-8, TGF-β1, MMP-1, MMP-3, EGF, and VEGF) and the lipid peroxidation product (MDA) were significantly increased in cells (P < 0.05), while the activity of antioxidant enzyme (SOD, GSH-Px, and CAT) was significantly decreased (P < 0.05), and an increased number of cells accumulated in the G1 phase (P < 0.05). Further Kaji-ichigoside F1 intervention experiments showed that compared to that in the arsenic-exposed group, the expression level of the activity of antioxidant enzyme was significantly increased in the Kaji-ichigoside F1 intervention group (P < 0.05), but the indicators of ERK/CEBPB signaling pathway, cell cycle-related genes, and SASP were significantly decreased (P < 0.05), and the cell cycle arrest relieved to a certain extent (P < 0.05). Our study provides some limited evidence that the ERK/CEBPB signaling pathway is involved in low-dose arsenic-induced skin cell senescence, through regulating oxidative stress. The second major finding was that Kaji-ichigoside F1 can downregulate the ERK/CEBPB signaling pathway and regulate the balance between oxidation and antioxidation, alleviating arsenic-induced skin cell senescence. This study provides experimental evidence for further understanding of Kaji-ichigoside F1, a natural medicinal plant that may be more effective in preventing and controlling arsenic poisoning.

Arsenic and Human Health: Genotoxicity, Epigenomic Effects, and Cancer Signaling

Arsenic is a well-known element because of its toxicity. Humans as well as plants and animals are negatively affected by its exposure. Some countries suffer from high levels of arsenic in their tap water and soils, which is considered a primary arsenic-linked risk factor for living beings. Humans generally get exposed to arsenic by contaminated drinking waters, resulting in many health problems, ranging from cancer to skin diseases. On the other hand, the FDA-certified drug arsenic trioxide provides solutions for various diseases, including several types of cancers. This issue emphasizes the importance of speciation of the metalloid elements in terms of impacts on health. When species get exposed to arsenic, it affects the cells altering their involvement. It can lead to abnormalities in inflammatory mechanisms and the immune system which contribute to the negative impacts generated on the body. The poisoning originating from arsenic gives rise to various biological signs on the body which can be useful for the diagnosis. It is important to find true biomarkers for the detection of arsenic poisoning. In view of its application in medicine and biology, studies on understanding the biological activity of arsenic have increased. In this review, we aim at summarizing the current state of knowledge of arsenic and the mechanism behind its toxicity including genotoxicity, oxidative insults, epigenomic changes, and alterations in cellular signaling.

Investigating the Neurotoxic Impacts of Arsenic and the Neuroprotective Effects of Dictyophora Polysaccharide Using SWATH-MS-Based Proteomics

Arsenic (As) is one of the most important toxic elements in the natural environment. Currently, although the assessment of the potential health risks of chronic arsenic poisoning has received great attention, the research on the effects of arsenic on the brain is still limited. It has been reported that dictyophora polysaccharide (DIP), a common bioactive natural compound found in dietary plants, could reduce arsenic toxicity. Following behavioral research, comparative proteomics was performed to explore the molecular mechanism of arsenic toxicity to the hippocampi of SD (Sprague Dawley) rats and the protective effect of DIP. The results showed that exposure to arsenic impaired the spatial learning and memory ability of SD rats, while DIP treatment improved both the arsenic-exposed rats. Proteomic analysis showed that arsenic exposure dysregulated the expression of energy metabolism, apoptosis, synapse, neuron, and mitochondria related proteins in the hippocampi of arsenic-exposed rats. However, DIP treatment reversed or restored the expression levels of these proteins, thereby improving the spatial learning and memory ability of arsenic-exposed rats. This study is the first to use high-throughput proteomics to reveal the mechanism of arsenic neurotoxicity in rats as well as the protective mechanism of DIP against arsenic neurotoxicity.

Gestational exposure to environmental cadmium induces placental apoptosis and fetal growth restriction via Parkin-modulated MCL-1 degradation

Heavy metal cadmium (Cd), a classical environmental pollutant, causes placental apoptosis and fetal growth restriction (FGR), whereby the mechanism remains unclear. Here, our human case-control study firstly showed that there was a positive association of Parkin mitochondrial translocation, MCL-1 reduction, placental apoptosis, and all-cause FGR. Subsequently, Cd was administered to establish in vitro and in vivo models of placental apoptosis or FGR. Our models demonstrated that Parkin mitochondrial translocation was observed in Cd-administrated placental trophoblasts. Meaningfully, Parkin siRNA (siR) dramatically mitigated Cd-triggered apoptosis in placental trophoblasts. Mdivi-1 (M-1), an inhibitor for Parkin mitochondrial translocation, mitigated Cd-induced apoptosis in placental trophoblasts, which further ameliorated the effect of attenuated placental sizes in Cd-exposed mice. Furthermore, the interaction of MCL-1 with Parkin or Ub in Cd-stimulated cells was stronger than that in controls. MG132, an inhibitor for proteasome, abolished MCL-1 degradation in Cd-stimulated cells. Importantly, Parkin siR and M-1 memorably abolished the ubiquitin-dependent degradation of MCL-1 in placental trophoblasts. Interestingly, mito-TEMPO and melatonin, two mitochondria-targeted antioxidants, obviously rescued Cd-caused mitochondrial membrane potential (MMP) decrease, Parkin mitochondrial translocation, MCL-1 degradation, and apoptosis in placental trophoblasts. In conclusion, cadmium induces placental apoptosis and FGR via mtROS-mediated Parkin-modulated degradation of MCL-1.

Arsenic causes mitochondrial biogenesis obstacles by inhibiting the AMPK/PGC-1α signaling pathway and also induces apoptosis and dysregulated mitophagy in the duck liver

Arsenic is a dangerous metalloid-material which is known to cause liver injury in many animals and humans. However, little is known about the underlying mechanism of arsenic-induced hepatotoxicity in poultry. This study was executed to systematically investigate the potential role of mitochondrial biogenesis, mitophagy and apoptosis in duck hepatotoxicity caused by arsenic. Results showed that the body weight and liver coefficient of duck had distinct changed after arsenic-exposure, and the arsenic content in serum and liver also increased significantly in a dose-dependent manner. Meanwhile, histopathological examination and metabolomics results showed that arsenic-exposure caused severe steatosis and metabolism disorder in liver tissues. Furthermore, arsenic-exposure significantly inhibited AMPK/PGC-1α-mediated mitochondrial biogenesis, determined by the ultrastructure observation and down-regulation of p-AMPKα/AMPKα, PGC-1α, NRF1, NRF2, TFAM, TFB1M, TFB2M and COX-Ⅳ expression levels. Besides, arsenic-treatment obviously increased the levels of mitophagy (PINK1, Parkin, LC3, P62) and pro-apoptotic (Caspase-3, Caspase-9, Cleaved Caspase-3, Cytc, Bax, P53) indexes, and simultaneously resulted in reductions in anti-apoptosis index (Bcl-2). Overall, our findings provided evidences that arsenic-induced duck hepatotoxicity may be caused by a combination of impaired mitochondrial biosynthesis, mitophagy, and mitochondrial-dependent apoptosis. To our knowledge, this is the first report to systematically investigate the potential mechanism of arsenic-induced hepatotoxicity in poultry.

Curcumin alleviates arsenic-induced injury in duck skeletal muscle via regulating the PINK1/Parkin pathway and protecting mitochondrial function

Arsenic is a well-known environmental pollutant due to its toxicity, which can do harm to animals and human. Curcumin is a polyphenolic compound derived from turmeric, commonly accepted to have antioxidant properties. However, whether curcumin can ameliorate the damage caused by arsenic trioxide (ATO) in duck skeletal muscle remains largely unknown. Therefore, the present study aims to investigate the potential molecular mechanism of curcumin against ATO-induced skeletal muscle injury. The results showed that treating with curcumin could attenuate body weight loss induced by ATO and reduced arsenic content accumulation in the skeletal muscle of duck. Curcumin was also able to alleviated the oxidative stress triggered by ATO, which was manifested by the increase of T-AOC and SOD, and MDA decrease. Moreover, we observed that curcumin could ease mitochondrial damage and vacuolate degeneration of nucleus. Our further investigation found that ATO disrupted normal mitochondrial fission/fusion (Drp1, OPA1, Mfn1/2) and restrained mitochondrial biogenesis (PGC-1α, Nrf1/2, TFAM), while curcumin could promote mitochondrial fusion and activated PGC-1α pathway. Furthermore, curcumin was found that it could not only reduce the mRNA and protein levels of mitophagy (PINK1, Parkin, LC3, p62) and pro-apoptotic genes (p53, Bax, Caspase-3, Cytc), but also increased the levels of anti-apoptotic genes (Bcl-2). In conclusion, curcumin was able to alleviate ATO-induced skeletal muscle damage by improving mitophagy and preserving mitochondrial function, which can serve as a novel strategy to take precautions against ATO toxicity.

Protective Effect of Dictyophora Polysaccharides on Sodium Arsenite-Induced Hepatotoxicity: A Proteomics Study

The purpose of this study is to understand the mechanism of sodium arsenite (NaAsO₂)-induced apoptosis of L-02 human hepatic cells, and how Dictyophora polysaccharide (DIP) protects L-02 cells from arsenic-induced apoptosis. The results revealed that DIP pretreatment inhibited NaAsO₂ induced L-02 cells apoptosis by increasing anti-apoptotic Bcl-2 expression and decreasing pro-apoptotic Bax expression. Proteomic analysis showed that arsenic treatment disrupted the expression of metabolism and apoptosis associated proteins, including ribosomal proteins (RPs). After pretreatment with DIP, the expression levels of these proteins were reversed or restored. For the first time, it was observed that the significant decrease of cytoplasmic RPs and the increase of mitochondrial RPs were related to human normal cell apoptosis induced by arsenic. This is also the first report that the protective effect of DIP on cells was related to RPs. The results highlight the relationship between RPs and apoptosis, as well as the relationship between RPs and DIP attenuating arsenic-induced apoptosis.

Effect of PINK1 and Parkin gene silencing on sodium arsenite-induced mitophagy in normal rat liver cells (BRL-3A)

NaAsO₂-induced liver damage leads to autophagy, which plays an important role in cell quality control. Mitophagy plays an important role in hepatocyte damage, and PINK1 and Parkin constitute an important pathway in mitophagy. PINK1 selectively degrades abnormal mitochondria, and Parkin can recognize damaged mitochondria. However, the mechanism underlying the involvement of PINK1/Parkin in NaAsO₂-induced mitophagy is unclear. Transfection plasmids containing dsRNA were used to interfere with the expression of Parkin in the following groups: the empty plasmid group was established by add the empty plasmid only, the PINK1-knockdown (KD) group was established by adding 5 μg of PINK1 dsRNA and then by adding 10 mM NaAsO₂, and the Parkin-KD group was established by adding 5 μg of Parkin dsRNA and then by adding 10 mM NaAsO₂. The expression of PINK1 and Parkin in autophagy was detected by western blotting and immunofluorescence staining. The ultrastructures of autophagosomes and mitochondria were observed by transmission electron microscopy. The successful KD of PINK1 and Parkin aggravated the NaAsO₂-induced damage to mitophagy. The degeneration of mitochondrial vacuoles and the appearance of autophagosomes were detected in the NaAsO₂, NaAsO₂ + PINK1-KD and NaAsO₂ + Parkin-KD groups. NaAsO₂ can induce mitophagy in rat hepatocytes, and the silencing of PINK1 and Parkin can aggravate mitochondrial damage during this process. This study explored the mechanism of NaAsO₂-induced mitophagy in BRL-3A cells after PINK1 and Parkin gene silencing.

Arsenic or/and antimony induced mitophagy and apoptosis associated with metabolic abnormalities and oxidative stress in the liver of mice

Arsenic and antimony are coexisting cumulative environmental pollutants that cause severe and extensive biological toxicity. However, their interactions and toxic mechanisms in the liver remain to be fully elucidated. In this study, a total of sixty 4-week-old mice were divided into four groups and treated with 4 mg/kg arsenic trioxide (ATO) or/and 15 mg/kg antimony (Sb) for 60 days. The results demonstrated that biochemical indicators of hepatotoxicity (ALT, AST, ALP) were upregulated in all treated groups. Additionally, the oxidative burden of the liver was increased in the cotreated groups compared with the individual toxicant-treated groups. Meanwhile, mitochondrial injury, autophagosomes, hepatic-congestion and karyopyknosis were obviously observed in cotreated groups. Additionally, coupled with serum biochemical index (TG, TC), histopathology examination and metabolomics results, we found that cotreatment with ATO and Sb resulted in lipid metabolism disorder and steatosis of liver tissues. Our further investigation found that the levels of pro-apoptotic (Caspase-3, Caspase-9, Bax, P53, Cytc) and mitophagy (LC3-B, P62, PINK1, Parkin) indexes in the cotreated groups were markedly increased, whereas the levels of anti-apoptosis index (Bcl-2) were decreased. Collectively, these results show that co-exposure to ATO and Sb can cause abnormal liver energy metabolism and oxidative stress. Moreover, mitophagy and apoptosis play important roles in the mechanisms of arsenic/antimony cytotoxicity to mouse livers.

DHA Protects Hepatocytes from Oxidative Injury through GPR120/ERK-Mediated Mitophagy

Oxidative stress occurs in a variety of clinical liver diseases and causes cellular damage and mitochondrial dysfunction. The clearance of damaged mitochondria by mitophagy may facilitate mitochondrial biogenesis and enhance cell survival. Although the supplementation of docosahexaenoic acid (DHA) has been recognized to relieve the symptoms of various liver diseases, the antioxidant effect of DHA in liver disease is still unclear. The purpose of our research was to investigate the antioxidant effect of DHA in the liver and the possible role of mitophagy in this. In vitro, H₂O₂-induced injury was caused in AML12 cells. The results showed that DHA repressed the level of reactive oxygen species (ROS) induced by H₂O₂ and stimulated the cellular antioxidation response. Most notably, DHA restored oxidative stress-impaired autophagic flux and promoted protective autophagy. In addition, PINK/Parkin-mediated mitophagy was activated by DHA in AML12 cells and alleviated mitochondrial dysfunction. The ERK1/2 signaling pathway was inhibited during oxidative stress but reactivated by DHA treatment. It was proven that the expression of ERK1/2 was involved in the regulation of mitophagy by the ERK1/2 inhibitor. We further proved these results in vivo. DHA effectively alleviated the liver oxidative damage caused by CCl₄ and enhanced antioxidation capacity; intriguingly, autophagy was also activated. In summary, our data demonstrated that DHA protected hepatocytes from oxidative damage through GPR120/ERK-mediated mitophagy.

TLR4-NLRP3-GSDMD-Mediated Pyroptosis Plays an Important Role in Aggravated Liver Injury of CD38-/- Sepsis Mice

Clinically, severe bacterial infection can cause septicemia and multiple organ dysfunction syndrome, especially liver injury. CD38 is closely related to many inflammatory pathways, but its role in liver injury caused by bacterial infection remains unclear. The purpose of this study is to discuss the specific role of CD38 in bacterial liver injury. Eight-week-old male C57BL/6 mice (WT, CD38^−/− and CD38^−/−TLR4^mut) were used and stimulated with Escherichia coli (ATCC25922) or PBS, intraperitoneally. After 3 hours of bacterial stimulation, serum was collected to detect ALT and AST concentration, and liver tissue was harvested for hematoxylin and eosin staining and bacterial culture. The mRNA expressions of TLR4, NLRP3, IL-1β, IL-18, and GSDMD were quantitatively determined by RT-qPCR. The expressions of TLR4, MyD88, TRIF, NF-κB p65, NLRP3, GSDMD, and cytokines were detected by Western blot. The expression and localization of ERK1/2 were detected by immunohistochemistry and Western blot. The results showed that bacterial stimulation could upregulate the expression of inflammatory cytokines, leading to hepatic dysfunction. Moreover, bacterial stimulation of CD38-deficient mice can aggravate the inflammatory response, the expressions of TLR4, NF-κB, and ERK1/2 were significantly increased, and the biomarkers related to pyroptosis also manifested more obvious pyroptosis. However, TLR4 mutation significantly alleviated inflammation and pyroptosis in the liver caused by bacteria, on the basis of CD38 deficiency. Overall, CD38 knockout exacerbates bacteria-induced liver damage through TLR4-NLRP3-GSDMD-mediated pyroptosis.

Regulating glucose metabolism using nanomedicines for cancer therapy

The regulation of glucose metabolism is a research focus in cancer treatment. Glucose metabolism is essential for maintaining the growth and proliferation of tumor cells, thus offering us great opportunities for tumor treatment. Recently, much progress has been made in efficient cancer treatment by regulating the pathway of glucose metabolism with nanomedicines due to the rapid development of nanotechnology and promising drug targets. In this review, we first introduced the pathway of cell energy supply from the perspective of aerobic and anaerobic processes. Then, we discussed the recent research progress in regulating glucose metabolism for various tumor resistance strategies including heat resistance, multiple drug resistance, and hypoxia. Finally, we presented the prospects and challenges of developing multifunctional nanoagents for efficient chemotherapy, hyperthermia, dynamic therapy and so on by regulating glucose metabolism.