Reactive oxygen species impair Na+ transport and renal components of the renin-angiotensin-aldosterone system after paraquat poisoning.

Paraquat (1,1'-dimethyl-4,4'-bipyridyl dichloride) is an herbicide widely used worldwide and officially banned in Brazil in 2020. Kidney lesions frequently occur, leading to acute kidney injury (AKI) due to exacerbated reactive O2 species (ROS) production. However, the consequences of ROS exposure on ionic transport and the regulator local renin-angiotensin-aldosterone system (RAAS) still need to be elucidated at a molecular level. This study evaluated how ROS acutely influences Na+-transporting ATPases and the renal RAAS. Adult male Wistar rats received paraquat (20 mg/kg; ip). After 24 h, we observed body weight loss and elevation of urinary flow and serum creatinine. In the renal cortex, paraquat increased ROS levels, NADPH oxidase and (Na++K+)ATPase activities, angiotensin II-type 1 receptors, tumor necrosis factor-α (TNF-α), and interleukin-6. In the medulla, paraquat increased ROS levels and NADPH oxidase activity but inhibited (Na++K+)ATPase. Paraquat induced opposite effects on the ouabain-resistant Na+-ATPase in the cortex (decrease) and medulla (increase). These alterations, except for increased serum creatinine and renal levels of TNF-α and interleukin-6, were prevented by 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (tempol; 1 mmol/L in drinking water), a stable antioxidant. In summary, after paraquat poisoning, ROS production culminated with impaired medullary function, urinary fluid loss, and disruption of Na+-transporting ATPases and angiotensin II signaling.

Exosomes from senescent epithelial cells activate pulmonary fibroblasts via the miR-217-5p/Sirt1 axis in paraquat-induced pulmonary fibrosis.

BACKGROUND: Paraquat (PQ) is a widely used and highly toxic herbicide that poses a significant risk to human health. The main consequence of PQ poisoning is pulmonary fibrosis, which can result in respiratory failure and potentially death. Our research aims to uncover a crucial mechanism in which PQ poisoning induces senescence in epithelial cells, ultimately regulating the activation of pulmonary fibroblasts through the exosomal pathway. METHODS: Cellular senescence was determined by immunohistochemistry and SA-ß-Gal staining. The expression of miRNAs was measured by qPCR. Pulmonary fibroblasts treated with specific siRNA of SIRT1 or LV-SIRT1 were used to analysis senescent exosomes-mediated fibroblasts activation. Luciferase reporter assay and western blot were performed to elucidated the underlying molecular mechanisms. The effects of miR-217-5p antagomir on pulmonary fibrosis were assessed in PQ-poisoned mice models. RESULTS: Impairing the secretion of exosomes effectively mitigates the harmful effects of senescent epithelial cells on pulmonary fibroblasts, offering protection against PQ-induced pulmonary fibrosis in mice. Additionally, we have identified a remarkable elevation of miR-217-5p expression in the exosomes of PQ-treated epithelial cells, which specifically contributes to fibroblasts activation via targeted inhibition of SIRT1, a protein involved in cellular stress response. Remarkably, suppression of miR-217-5p effectively impaired senescent epithelial cells-induced fibroblasts activation. Further investigation has revealed that miR-217-5p attenuated SIRT1 expression and subsequently resulted in enhanced acetylation of ß-catenin and Wnt signaling activation. CONCLUSION: These findings highlight a potential strategy for the treatment of pulmonary fibrosis induced by PQ poisoning. Disrupting the communication between senescent epithelial cells and pulmonary fibroblasts, particularly by targeting the miR-217-5p/SIRT1/ß-catenin axis, may be able to alleviate the effects of PQ poisoning on the lungs.

Protective effects of natural compounds against paraquat-induced pulmonary toxicity: the role of the Nrf2/ARE signaling pathway.

Paraquat (PQ) is a toxic herbicide to humans. Once absorbed, it accumulates in the lungs. PQ has been well documented that the generation of reactive oxygen species (ROS) is the main mechanism of its toxicity. Oxidative damage of PQ in lungs is represented as generation of cytotoxic and fibrotic mediators, interruption of epithelial and endothelial barriers, and inflammatory cell infiltration. No effective treatment for PQ toxicity is currently available. Several studies have shown that natural compounds (NCs) have the potential to alleviate PQ-induced pulmonary toxicity, due to their antioxidant and anti-inflammatory effects. NCs function as protective agents through stimulation of nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathways. Elevation of Nrf2 levels leads to the expression of its downstream enzymes such as SOD, CAT, and HO-1. The hypothesized role of the Nrf2/ARE signaling pathway as the protective mechanism of NCs against PQ-induced pulmonary toxicity is reviewed.

Methyl viologen-induced changes in the Arabidopsis proteome implicate PATELLIN 4 in oxidative stress responses.

The photosynthesis-induced accumulation of reactive oxygen species in chloroplasts can lead to oxidative stress, triggering changes in protein synthesis, degradation, and the assembly/disassembly of protein complexes. Using shot-gun proteomics, we identified methyl viologen-induced changes in protein abundance in wild-type Arabidopsis and oxidative stress-hypersensitive fsd1-1 and fsd1-2 knockout mutants, which are deficient in IRON SUPEROXIDE DISMUTASE 1 (FSD1). The levels of proteins that are localized in chloroplasts and the cytoplasm were modified in all lines treated with methyl viologen. Compared with the wild-type, fsd1 mutants showed significant changes in metabolic protein and chloroplast chaperone levels, together with increased ratio of cytoplasmic, peroxisomal, and mitochondrial proteins. Different responses in proteins involved in the disassembly of photosystem II-light harvesting chlorophyll a/b binding proteins were observed. Moreover, the abundance of PATELLIN 4, a phospholipid-binding protein enriched in stomatal lineage, was decreased in response to methyl viologen. Reverse genetic studies using patl4 knockout mutants and a PATELLIN 4 complemented line indicate that PATELLIN 4 affects plant responses to oxidative stress by effects on stomatal closure.

Targeted upregulation of dMyc restricts JNK-mediated degeneration of dopaminergic neurons in the paraquat-induced Parkinson's disease model of Drosophila.

Parkinson's disease is the second most common neurodegenerative disease characterized by the loss of dopaminergic neurons in the brain. Parkinson's disease has both familial and sporadic cases of origin governed differentially by genetic and/or environmental factors. Different epidemiological studies have proposed an association between the pathogenesis of cancer and Parkinson's disease; however, a precise correlation between these two illnesses could not be established yet. In this study, we examined the disease-modifying property of dmyc (a Drosophila homolog of human cmyc proto-oncogene) in the paraquat-induced sporadic Parkinson's disease model of Drosophila. We report for the first time that targeted upregulation of dMyc significantly restricts paraquat-mediated neurotoxicity. We observed that paraquat feeding reduces the cellular level of dMyc. We further noted that targeted upregulation of dMyc in paraquat-exposed flies mitigates degeneration of dopaminergic neurons by reinstating the aberrantly activated JNK pathway, and this in turn improves the motor performance and survival rate of the flies. Our study provides the first evidence that improved cellular level of dMyc could efficiently minimize the neurotoxic effects of paraquat, which could be beneficial in designing novel therapeutic strategies against Parkinson's disease.

Paraquat (herbicide) as a cause of Parkinson's Disease.

The four features of Parkinson's disease (PD), which also manifests other non-motor symptoms, are bradykinesia, tremor, postural instability, and stiffness. The pathogenic causes of Parkinsonism include Lewy bodies, intracellular protein clumps of αsynuclein, and the degeneration of dopaminergic neurons in the substantia nigra's pars compacta region. The pathophysiology of PD is still poorly understood due to the complexity of the illness. The apoptotic cell death of neurons in PD, however, has been linked to a variety of intracellular mechanisms, according to a wide spectrum of study. The endoplasmic reticulum's stress, decreased levels of neurotrophic factors, oxidative stress, mitochondrial dysfunction, catabolic alterations in dopamine, and decreased activity of tyrosine hydroxylase are some of these causes. The herbicide paraquat has been used in laboratory studies to create a variety of PD pathological features in numerous in-vitro and in-vivo animals. Due to the unique neurotoxicity that paraquat causes, understanding of the pathophysiology of PD has changed. Parkinson's disease (PD) is more likely to develop among people exposed to paraquat over an extended period of time, according to epidemiological studies. Thanks to this paradigm, the hunt for new therapy targets for PD has expanded. In both in-vitro and in-vivo models, the purpose of this study is to summarise the relationship between paraquat exposure and the onset of Parkinson's disease (PD).

The Peptide DHα-(4-pentenyl)-ANPQIR-NH2 Exhibits Antifibrotic Activity in Multiple Pulmonary Fibrosis Models Induced by Particulate and Soluble Chemical Fibrogenic Agents.

Interstitial lung diseases (ILDs) are a group of restrictive lung diseases characterized by interstitial inflammation and pulmonary fibrosis. The incidence of ILDs associated with exposure to multiple hazards such as inhaled particles, fibers, and ingested soluble chemicals is increasing yearly, and there are no ideal drugs currently available. Our previous research showed that the novel and low-toxicity peptide DHα-(4-pentenyl)-ANPQIR-NH2 (DR3penA) had a strong antifibrotic effect on a bleomycin-induced murine model. Based on the druggability of DR3penA, we sought to investigate its effects on respirable particulate silicon dioxide (SiO2)- and soluble chemical paraquat (PQ)-induced pulmonary fibrosis in this study by using western blot, quantitative reverse-transcription polymerase chain reaction (RT-qPCR), immunofluorescence, H&E and Masson staining, immunohistochemistry, and serum biochemical assays. The results showed that DR3penA alleviated the extent of fibrosis by inhibiting the expression of fibronectin and collagen I and suppressed oxidative stress and epithelial-mesenchymal transition (EMT) in vitro and in vivo. Further study revealed that DR3penA may mitigate pulmonary fibrosis by negatively regulating the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway and mitogen-activated protein kinase (MAPK) pathway. Unexpectedly, through the conversion of drug bioavailability under different routes of administration, DR3penA exerted antifibrotic effects equivalent to those of the positive control drug pirfenidone (PFD) at lower doses. In summary, DR3penA may be a promising lead compound for various fibrotic ILDs. SIGNIFICANCE STATEMENT: Our study verified that DHα-(4-pentenyl)-ANPQIR-NH2 (DR3penA) exhibited positive antifibrotic activity in pulmonary fibrosis induced by silicon dioxide (SiO2) particles and soluble chemical paraquat (PQ) and demonstrated a low-dose advantage compared to the small-molecule drug pirfenidone (PFD). The peptide DR3penA can be further developed for the treatment of multiple fibrotic lung diseases.

Cannabidiol Protects Dopaminergic-like Neurons against Paraquat- and Maneb-Induced Cell Death through Safeguarding DJ-1CYS106 and Caspase 3 Independently of Cannabinoid Receptors: Relevance in Parkinson's Disease.

Parkinson's disease (PD), a progressive neurodegenerative movement disorder, has reached pandemic status worldwide. This neurologic disorder is caused primarily by the specific deterioration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNc). Unfortunately, there are no therapeutic agents that slow or delay the disease progression. Herein, menstrual stromal cell-derived dopamine-like neurons (DALNs) intoxicated with paraquat (PQ2+)/maneb (MB) were used as a model system to elucidate the mechanism by which CBD protects the neural cell from apoptosis in vitro. According to immunofluorescence microscopy, flow cytometry, cell-free assay, and molecular docking analysis, we demonstrate that CBD offers protection to DALNs against PQ2+ (1 mM)/MB (50 µM)-induced oxidative stress (OS) by simultaneously (i) decreasing reactive oxygen species (ROS: O2•-, H2O2), (ii) maintaining the mitochondrial membrane potential (ΔΨm), (iii) directly binding to stress sensor protein DJ-1, thereby blunting its oxidation from DJ-1CYS106-SH into DJ-1CYS106-SO3, and (iv) directly binding to pro-apoptotic protease protein caspase 3 (CASP3), thereby disengaging neuronal dismantling. Furthermore, the protective effect of CBD on DJ-1 and CASP3 was independent of CB1 and CB2 receptor signaling. CBD also re-established the Ca2+ influx in DALNs as a response to dopamine (DA) stimuli under PQ2+/MB exposure. Because of its powerful antioxidant and antiapoptotic effects, CBD offers potential therapeutic utility in the treatment of PD.

Role of NF-κB/IL-1ß Pathway and Caspase 3 in Mediating the Hepatoprotective Effect of Rutin against Paraquat-Induced Liver Toxicity in Male Rats.

One of the most common bipyridinium herbicides that can lead to liver toxicity is paraquat. Rutin is a bioflavonoid with antioxidant, anti-inflammatory, anti-hepatotoxic, and antimicrobial properties. The effect of rutin on paraquat-induced liver toxicity was examined in this study. 48 male rats were divided into six groups: the control group was given a normal diet; the non-treated group was given paraquat; the positive control group was given paraquat, and silymarin and the treatment groups were given paraquat and rutin at doses of 25, 50, and 100 mg/kg. After fourteen days, the rats were anesthetized by xylazine-ketamine, and fasting blood samples were obtained from their hearts to measure alkaline phosphatase (ALP), aspartate transaminase (AST), alanine transaminase (ALT), malondialdehyde (MDA), creatinine, lipid profile, antioxidant capacity, and carbonyl protein. The liver tissue was removed to measure the levels of catalase (CAT), superoxide dismutase (SOD), total protein, vitamin C, plus NF-κB, IL1ß, and caspase-3 gene expressions. Paraquat gavage in the untreated group (group 2) for 14 days in comparison with the control group induced a significant augmentation (p<0.05) in levels of lipid profile, AST, ALP, ALT, MDA, carbonyl protein, and also NF-κB, IL1ß, Caspase3 expressions. Treatment with rutin reduced the factors as mentioned above. Paraquat poisoning induced a substantial decline (p<0.05) in HDL content, FRAP level, CAT, and SOD activity of the liver compared to the control group. However, rutin oral treatment led to a substantial increase (p<0.05) in the level of these factors compared to the paraquat-only treated group. Based on the findings of the present study, it was found that rutin can be significantly effective in improving hepatotoxicity caused by paraquat.

The role of the antioxidant system and the photosynthetic behavior of paraquat-resistant Conyza sumatrensis in Brazil.

Greenhouse experiments were carried out aiming to characterize-morphologically and biochemically-resistant and susceptible plants of C. sumatrensis. Two experiments were carried out to evaluate the behavior of morphological variables such as leaf area, height, and dry biomass weight, without application of paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride). Other experiments were conducted with two rates of paraquat application (0 and 800 g a.i ha-1); physiological variables were assessed at 2, 4, and 24 h after application (HAA), and plants were collected at 4 HAA for biochemical analyses of antioxidant enzymes and cell membrane peroxidation level. Without herbicide application, paraquat-resistant populations had higher dry biomass, leaf area, liquid photosynthetic rate, carboxylation efficiency, and stomatal conductance. The recovery of the photosynthetic apparatus by resistant plants after paraquat application is rapid (16 HAA) and, in general, presents physiological improvements in terms of photosynthetic rate and carboxylation efficiency. After paraquat treatment, the antioxidant system enzymes of resistant plants showed increased activity and decreased membrane peroxidation, indicating that these enzymes play an important role in the resistance mechanism of these plants.

Insulin Signaling Disruption and INF-γ Upregulation Induce Aß1-42 and Hyperphosphorylated-Tau Proteins Synthesis and Cell Death after Paraquat Treatment of Primary Hippocampal Cells.

Acute and long-term paraquat (PQ) exposure produces hippocampal neurodegeneration and cognition decline. Although some mechanisms involved in these effects were found, the rest are unknown. PQ treatment, for 1 and 14 days, upregulated interferon-gamma signaling, which reduced insulin levels and downregulated the insulin pathway through phosphorylated-c-Jun N-terminal-kinase upregulation, increasing glucose levels and the production of Aß1-42 and phosphorylated-tau, by beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) overexpression and phosphorylated-GSK3ß (p-GSK3ß; ser9) level reduction, respectively, which induced primary hippocampal neuronal loss. This novel information on the PQ mechanisms leading to hippocampal neurodegeneration could help reveal the PQ actions that lead to cognition dysfunction.

Study of paraquat-induced pulmonary fibrosis using biomimetic micro-lung chips.

Paraquat (PQ) poisoning induces pulmonary fibrosisin vivo. The pathogenesis of pulmonary fibrosis is complex, which has prevented the development of specific treatments. Pulmonary fibrosis shows several characteristics including epithelial-mesenchymal transition (EMT), fibroblast activation, and extracellular matrix (ECM) deposition. To investigate pulmonary fibrosis, we designed a biomimetic multichannel micro-lung chip to imitate thein vivointerface between the lung epithelium and the lung interstitium. In our model, A549 (lung epithelial cells) and MRC-5 (fetal lung fibroblasts) cells were used to test the efficacy of our chip-based model. Rat tail type I collagen and hyaluronic acid were used to simulate ECM and to provide a 3D microenvironment. The micro-lung chips were cultured with PQ (0, 75, 150, 300, and 400µM). The viability of A549 and MRC-5 cells significantly decreased with increasing PQ concentrations. There were significant changes in surfactant proteins C (SP-C), alpha smooth muscle actin protein (α-SMA), and vimentin protein levels during PQ-induced pulmonary fibrosis. SP-C levels were decreased in A549 cells, while those ofα-SMA and vimentin were increased in A549 cells and MRC-5 cells treated with PQ in the micro-lung chip. We also designed a reference model without interaction between the lung epithelial cells and fibroblasts. Compared to the non-contact model, co-culturing A549 and MRC-5 cells in chips induced more severe EMT in A549 cells after treatment with 75µM PQ and together defended against PQ-induced damage. Thus, our novel co-culture micro-lung chip that models the lung epithelium and interstitium may provide a new approach for studying lung fibrosis and will facilitate drug development.

Antioxidant potential of Pediococcus pentosaceus strains from the sow milk bacterial collection in weaned piglets.

BACKGROUND: In modern animal husbandry, breeders pay increasing attention to improving sow nutrition during pregnancy and lactation to favor the health of neonates. Sow milk is a main food source for piglets during their first three weeks of life, which is not only a rich repository of essential nutrients and a broad range of bioactive compounds, but also an indispensable source of commensal bacteria. Maternal milk microorganisms are important sources of commensal bacteria for the neonatal gut. Bacteria from maternal milk may confer a health benefit on the host. METHODS: Sow milk bacteria were isolated using culturomics followed by identification using 16S rRNA gene sequencing. To screen isolates for potential probiotic activity, the functional evaluation was conducted to assess their antagonistic activity against pathogens in vitro and evaluate their resistance against oxidative stress in damaged Drosophila induced by paraquat. In a piglet feeding trial, a total of 54 newborn suckling piglets were chosen from nine sows and randomly assigned to three treatments with different concentrations of a candidate strain. Multiple approaches were carried out to verify its antioxidant function including western blotting, enzyme activity analysis, metabolomics and 16S rRNA gene amplicon sequencing. RESULTS: The 1240 isolates were screened out from the sow milk microbiota and grouped into 271 bacterial taxa based on a nonredundant set of 16S rRNA gene sequencing. Among 80 Pediococcus isolates, a new Pediococcus pentosaceus strain (SMM914) showed the best performance in inhibition ability against swine pathogens and in a Drosophila model challenged by paraquat. Pretreatment of piglets with SMM914 induced the Nrf2-Keap1 antioxidant signaling pathway and greatly affected the pathways of amino acid metabolism and lipid metabolism in plasma. In the colon, the relative abundance of Lactobacillus was significantly increased in the high dose SMM914 group compared with the control group. CONCLUSION: P. pentosaceus SMM914 is a promising probiotic conferring antioxidant capacity by activating the Nrf2-Keap1 antioxidant signaling pathway in piglets. Our study provided useful resources for better understanding the relationships between the maternal microbiota and offspring. Video Abstract.

[Dynamic changes of locus coeruleus damage in Parkinson's disease-like mice induced by paraquat].

Objective: To observe the dynamic changes of brainstem locus coeruleus (LC) damage in Parkinson' s disease (PD) -like mice by paraquat (PQ) . Methods: In October 2019, 36 male C57BL/6 mice were randomly divided into the exposure group and the control group, with 18 mice in each group. The mice in the exposure group were given intraperitoneal injection of 15 mg/kg PQ, and the mice in the control group were given intraperitoneal injection of 0.9% saline, twice a week for 8 weeks. Neurobehavioral changes (pole climbing test, swimming test, open field test, tail hanging test, high plus maze test and water maze test) were observed at 4 weeks, 6 weeks and 8 weeks, respectively, and the changes of motor ability, emotion and cognitive function were evaluated. The brain tissue of mice were taken and stained with Hematoxylin-Eosin (HE) to observe the pathological changes of LC. Nissl staining was used to detect the changes of neuronal Nissl bodies in LC. Immunohistochemistry (IHC) staining was used to detect the expression of neuron nuclear antigen (NeuN) , dopamine (DA) neurons and norepinephrine (NE) neuron markers tyrosine hydroxylase (TH) , α-synuclein (α-syn) in substantia nigra (SN) and LC. The expression levels of NeuN, TH and α-syn in the midbrain and brainstem were detected by Western blotting. TUNEL staining was used to detect neuronal apoptosis in LC. Results: Compared with the 4th week of PQ exposure group, the time of pole climbing and swimming immobility were gradually increased, the ratio of open arm residence time of high plus maze test and the number of times of the platform and the residence time of platform quadrant in water maze test were gradually decreased (P<0.05) in the exposure group with the progress of exposure time. The results of HE and Nissl staining showed that the neurons in LC gradually arranged loosely, the nucleus were deeply stained, the cytoplasm was pyknosis, and the number of Nissl bodies gradually decreased (P<0.05) in the exposure group with the progress of exposure time. IHC results showed that the number of NeuN and TH positive cells in SN and LC of mice were gradually decreased, and the positive expression of α-syn was gradually increased (P<0.05) in the exposure group with the progress of exposure time. Western blotting results showed that the expression levels of NeuN and TH in the midbrain and brainstem were gradually decreased, and the expression level of α-syn was gradually increased (P<0.05) in the exposure group with the progress of exposure time. TUNEL staining showed that the apoptosis rates of neurons in LC were gradually increased (P<0.05) in the exposure group with the progress of exposure time. Conclusion: PQ induces progressive damage in the LC area of PD-like mice, which may be caused by the abnormal accumulation of pathological α-syn in the LC area.

Small paraquat resistance proteins modulate paraquat and ABA responses and confer drought tolerance to overexpressing Arabidopsis plants.

Adaptation of higher plants to extreme environmental conditions is under complex regulation. Several small peptides have recently been described to modulate responses to stress conditions. The Small Paraquat resistance protein (SPQ) of Lepidium crassifolium has previously been identified due to its capacity to confer paraquat resistance to overexpressing transgenic Arabidopsis plants. Here, we show that overexpression of the closely related Arabidopsis SPQ can also enhance resistance to paraquat, while the Arabidopsis spq1 mutant is slightly hypersensitive to this herbicide. Besides being implicated in paraquat response, overexpression of SPQs enhanced sensitivity to abscisic acid (ABA), and the knockout spq1 mutant was less sensitive to ABA. Both Lepidium- and Arabidopsis-derived SPQs could improve drought tolerance by reducing water loss, stabilizing photosynthetic electron transport and enhancing plant viability and survival in a water-limited environment. Enhanced drought tolerance of SPQ-overexpressing plants could be confirmed by characterizing various parameters of growth, morphology and photosynthesis using an automatic plant phenotyping platform with RGB and chlorophyll fluorescence imaging. Our results suggest that SPQs can be regulatory small proteins connecting ROS and ABA regulation and through that influence responses to certain stresses.

Tracing brain genotoxic stress in Parkinson's disease with a novel single-cell genetic sensor.

To develop an in vivo tool to probe brain genotoxic stress, we designed a viral proxy as a single-cell genetic sensor termed PRISM that harnesses the instability of recombinant adeno-associated virus genome processing and a hypermutable repeat sequence-dependent reporter. PRISM exploits the virus-host interaction to probe persistent neuronal DNA damage and overactive DNA damage response. A Parkinson's disease (PD)-associated environmental toxicant, paraquat (PQ), inflicted neuronal genotoxic stress sensitively detected by PRISM. The most affected cell type in PD, dopaminergic (DA) neurons in substantia nigra, was distinguished by a high level of genotoxic stress following PQ exposure. Human alpha-synuclein proteotoxicity and propagation also triggered genotoxic stress in nigral DA neurons in a transgenic mouse model. Genotoxic stress is a prominent feature in PD patient brains. Our results reveal that PD-associated etiological factors precipitated brain genotoxic stress and detail a useful tool for probing the pathogenic significance in aging and neurodegenerative disorders.

The herbicide paraquat alters growth and melanin production on the Cryptococcus neoformans/Cryptococcus gattii species complex.

Paraquat (1,10-dimethyl-4,4-bipyridinium dichloride; PQ) is a free-radical producing herbicide that affects cell membranes and can upset the environmental balance of microorganisms present in soil, such as Cryptococcus spp. This study aimed to evaluate the in vitro activity of PQ against Cryptococcus spp. in planktonic and biofilm forms, as well as the protective effect of antioxidant agents against the antifungal effect of PQ and the kinetics of melanin production in response to PQ. Susceptibility to PQ was evaluated by microdilution. Cryptococcus sp. strains exposed to PQ were grown in media with ascorbic acid (AA) and glutathione (GSH). Melanin production was assessed in the presence of l-3,4-dihydroxyphenylalanine (l-DOPA) + PQ. The minimum inhibitory concentration of PQ against Cryptococcus spp. ranged from 8 to 256 µg/mL. Furthermore, PQ reduced biofilm formation. AA and GSH restored the fungal growth of Cryptococcus spp. exposed to PQ. In addition, l-DOPA + PQ delayed melanin production by 24 and 48 h for C. deuterogattii and C. neoformans sensu lato, respectively, suggesting that PQ induces a fitness trade-off in melanin production. Taken together, our data suggest that the antifungal effect of PQ against Cryptococcus spp. possibly exerts selective pressures interfering with biofilm formation and melanin production by these yeasts.

Stimulation of de novo glutathione synthesis by nitrofurantoin for enhanced resilience of hepatocytes.

Toxicity is not only a function of damage mechanisms, but is also determined by cellular resilience factors. Glutathione has been reported as essential element to counteract negative influences. The present work hence pursued the question how intracellular glutathione can be elevated transiently to render cells more resistant toward harmful conditions. The antibiotic nitrofurantoin (NFT) was identified to stimulate de novo synthesis of glutathione in the human hepatoma cell line, HepG2, and in primary human hepatocytes. In intact cells, activation of NFT yielded a radical anion, which subsequently initiated nuclear-factor-erythroid 2-related-factor-2 (Nrf2)-dependent induction of glutamate cysteine ligase (GCL). Application of siRNA-based intervention approaches confirmed the involvement of the Nrf2-GCL axis in the observed elevation of intracellular glutathione levels. Quantitative activation of Nrf2 by NFT, and the subsequent rise in glutathione, were similar as observed with the potent experimental Nrf2 activator diethyl maleate. The elevation of glutathione levels, observed even 48 h after withdrawal of NFT, rendered cells resistant to different stressors such as the mitochondrial inhibitor rotenone, the redox cycler paraquat, the proteasome inhibitors MG-132 or bortezomib, or high concentrations of NFT. Repurpose of the antibiotic NFT as activator of Nrf2 could thus be a promising strategy for a transient and targeted activation of the endogenous antioxidant machinery. Graphical abstract.

ABC transporter slr0982 affects response of Synechocystis sp. PCC 6803 to oxidative stress caused by methyl viologen.

The exposure of methyl viologen (a bipyridine salt) can lead to the production of reactive oxygen species, causing oxidative stress to organisms. ABC transporters have been reported to be involved in multi-drug resistance and have a role in MV detoxification. Here, we performed a protein structure simulation of the Slr0982 protein encoding ABC transporters, and confirmed that the region from Phe57 to Gln257 was the ABC transporter-type domain of the Slr0982 protein. The results of protein sequence alignment showed that Slr0982 protein was similar to Slr2108 protein (polysialic acid transport ATP-binding protein) and Slr0354 protein (ABC transporter). We reported that the mutation of slr0982 reduced the tolerance of Synechocystis sp. PCC 6803 to oxidative stress induced by methyl viologen. The deletion of slr0982 reduced the ability of cells to resist oxidative stress. Our data confirmed that the deletion of slr0982 could affect the concentration of exopolysaccharide and the expression of some genes related to carbohydrate metabolism, thus decreasing polysaccharide transport. Importantly, the exogenous addition of exopolysaccharide extracted from wild type can effectively reduce the oxidative damage to Δslr0982 by methyl viologen. This study expands the role of ABC transporters in MV-induced oxidative stress and provides an insight into the further analysis of the response of cyanobacteria to oxidative stress.

Paraquat exposure impairs porcine oocyte meiotic maturation.

Paraquat (PQ) is a heterocyclic pesticide that not only damages the testicular development and reduces the quality of semen, but also disturbs the secretion of hormones in the reproductive system. However, the effects of PQ on oocyte maturation and its toxic mechanism have not been yet fully clarified. Here we showed that PQ exposure could have toxic effects on porcine oocyte maturation. PQ exposure with 100 µM inhibited cumulus cell expansion and significantly reduced the rate of first polar body extrusion during oocyte maturation. PQ-exposed oocytes could not develop to the 2-cell and blastocyst stage. PQ exposure with 100 µM significantly increased abnormal spindle rate (65.2% ± 1.0%) and misaligned chromosome rate (63.2% ± 3.4%) compared to the control group (38.3% ± 1.0% and 38.4% ± 1.0%, respectively; P < 0.05). F-actin also exhibited reduced distribution in PQ-exposed oocytes (10.3% ± 1.0%) compared to the control group (14.4% ± 1.0%, P < 0.05). In addition, PQ exposure reduced the active mitochondria levels, but apparently increased the reactive oxygen species (ROS), rH2AX, and LC3 (autophagy marker) levels. qPCR analyses showed that PQ exposure caused the aberrant expression of genes associated with cumulus cell expansion, but did not affect the expression of apoptosis-related genes. Taken together, these results indicate that PQ exposure impaired oocyte nuclear and cytoplasmic maturation probably through oxidative stress.