Regulation of patulin-induced oxidative stress processes in the fission yeast Schizosaccharomyces pombe

Molecular Response of Meyerozyma guilliermondii to Patulin: Transcriptomic-Based Analysis

Patulin (PAT), mainly produced by Penicillium expansum, is a potential threat to health. In recent years, PAT removal using antagonistic yeasts has become a hot research topic. Meyerozyma guilliermondii, isolated by our group, produced antagonistic effects against the postharvest diseases of pears and could degrade PAT in vivo or in vitro. However, the molecular responses of M. guilliermondii over PAT exposure and its detoxification enzymes are not apparent. In this study, transcriptomics is used to unveil the molecular responses of M. guilliermondii on PAT exposure and the enzymes involved in PAT degradation. The functional enrichment of differentially expressed genes indicated that the molecular response mainly includes the up-regulated expression of genes related to resistance and drug-resistance, intracellular transport, growth and reproduction, transcription, DNA damage repair, antioxidant stress to avoid cell damage, and PAT detoxification genes such as short-chain dehydrogenase/reductases. This study elucidates the possible molecular responses and PAT detoxification mechanism of M. guilliermondii, which could be helpful to further accelerate the commercial application of antagonistic yeast toward mycotoxin decontamination.

Removal of patulin by thiol-compounds: A review

Patulin (PAT) is a toxic mycotoxin usually contaminated apple juices, which leads to a serious food safety issue in the world. Thiol-compounds are a class of compounds containing the thiol (-SH) group themselves or obtained the -SH group by physical or chemical modification. They have the ability to efficiently remove patulin in apple juices with manifested negligible effects on juice quality. This review investigates the latest development in the removal of patulin using thiol-compounds, including the removal efficiencies and mechanisms of patulin, the factors influencing the removal efficiency of patulin, as well as the toxicities of thiol-compounds and safety of juices after detoxification. This review shows that thiol-compounds are promising materials for the removal or degradation of patulin in the contaminated juices.

Cardiotoxicity of patulin was found in H9c2 cells

Patulin (PAT) is a kind of mycotoxins that is universally found at rotten fruits, especially apples and apple products. Previous studies have shown that PAT has hepatotoxicity and nephrotoxicity. However, cardiotoxicity of PAT is rarely reported. Present study aimed at investigate the cardiotoxicity and relevant mechanisms of PAT on H9c2 cells. Cytotoxicity of PAT were evaluated by MTT assay and LDH. Hoechst 33258 staining was used to examine the nuclear morphology and AV/PI double staining was employed for apoptosis on H9c2 cells. Expression level of Caspase-3, Caspase-9, Bax, Bcl-2 were quantified to verify the potential mechanism of mitochondrial apoptosis pathway. The tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and interleukin 6 (IL-6) were quantified to determine the inflammatory response by using ELISA assay. ROS, SOD, MDA, GSH levels were measured to determine the oxidative stress status. Results demonstrated that PAT significantly induced cell injury, as evidenced by the down-regulated of cell viability, and the increase of LDH release. Hoesst33258 staining and flow cytometry showed that apoptosis rate was elevated by PAT. PAT treatment up-regulated the expression of Caspase-3, Caspase-9, Bax level and down-regulated the expression of Bcl-2 level. TNF-α, IL-1β, IL-6 levels showed that PAT increased the pro-inflammatory response. As PAT concentration increased, intracellular MDA, ROS content were elevated, while GSH content and the activity of SOD were significantly decreased. Thus, it is concluded that PAT may induce apoptosis of H9c2 cells through oxidative stress.

Molecular Aspects of Mycotoxins-A Serious Problem for Human Health

Mycotoxins are toxic fungal secondary metabolities formed by a variety of fungi (moulds) species. Hundreds of potentially toxic mycotoxins have been already identified and are considered a serious problem in agriculture, animal husbandry, and public health. A large number of food-related products and beverages are yearly contaminated by mycotoxins, resulting in economic welfare losses. Mycotoxin indoor environment contamination is a global problem especially in less technologically developed countries. There is an ongoing effort in prevention of mould growth in the field and decontamination of contaminated food and feed in order to protect human and animal health. It should be emphasized that the mycotoxins production by fungi (moulds) species is unavoidable and that they are more toxic than pesticides. Human and animals are exposed to mycotoxin via food, inhalation, or contact which can result in many building-related illnesses including kidney and neurological diseases and cancer. In this review, we described in detail the molecular aspects of main representatives of mycotoxins, which are serious problems for global health, such as aflatoxins, ochratoxin A, T-2 toxin, deoxynivalenol, patulin, and zearalenone.

The Aspergilli and Their Mycotoxins: Metabolic Interactions With Plants and the Soil Biota

Species of the highly diverse fungal genus Aspergillus are well-known agricultural pests, and, most importantly, producers of various mycotoxins threatening food safety worldwide. Mycotoxins are studied predominantly from the perspectives of human and livestock health. Meanwhile, their roles are far less known in nature. However, to understand the factors behind mycotoxin production, the roles of the toxins of Aspergilli must be understood from a complex ecological perspective, taking mold-plant, mold-microbe, and mold-animal interactions into account. The Aspergilli may switch between saprophytic and pathogenic lifestyles, and the production of secondary metabolites, such as mycotoxins, may vary according to these fungal ways of life. Recent studies highlighted the complex ecological network of soil microbiotas determining the niches that Aspergilli can fill in. Interactions with the soil microbiota and soil macro-organisms determine the role of secondary metabolite production to a great extent. While, upon infection of plants, metabolic communication including fungal secondary metabolites like aflatoxins, gliotoxin, patulin, cyclopiazonic acid, and ochratoxin, influences the fate of both the invader and the host. In this review, the role of mycotoxin producing Aspergillus species and their interactions in the ecosystem are discussed. We intend to highlight the complexity of the roles of the main toxic secondary metabolites as well as their fate in natural environments and agriculture, a field that still has important knowledge gaps.

Cytotoxic Action of Artemisinin and Scopoletin on Planktonic Forms and on Biofilms of Candida Species

We investigated the antifungal activities of purified plant metabolites artemisinin (Ar) and scopoletin (Sc) including inhibition, effects on metabolic activities, viability, and oxidative stress on planktonic forms and on preformed biofilms of seven Candida species. The characteristic minimum inhibitory concentration (MIC90) of Ar and Sc against Candida species ranged from 21.83-142.1 µg/mL and 67.22-119.4 µg/mL, respectively. Drug concentrations causing ≈10% CFU decrease within 60 minutes of treatments were also determined (minimum effective concentration, MEC10) using 100-fold higher CFUs than in the case of MIC90 studies. Cytotoxic effects on planktonic and on mature biofilms of Candida species at MEC10 concentrations were further evaluated with fluorescent live/dead discrimination techniques. Candida glabrata, Candida guilliermondii, and Candida parapsilosis were the species most sensitive to Ar and Sc. Ar and Sc were also found to promote the accumulation of intracellular reactive oxygen species (ROS) by increasing oxidative stress at their respective MEC10 concentrations against the tested planktonic Candida species. Ar and Sc possess dose-dependent antifungal action but the underlying mechanism type (fungistatic and fungicidal) is not clear yet. Our data suggest that Ar and Sc found in herbal plants might have potential usage in the fight against Candida biofilms.

S-Adenosylmethionine-Dependent Methyltransferase Helps Pichia caribbica Degrade Patulin

Patulin contamination not only is a menace to human health but also causes serious environmental problems worldwide due to the synthetic fungicides that are used to control it. This study focused on investigating the patulin degradation mechanism in Pichia caribbica at the molecular level. According to the results, P. caribbica (2 × 10⁶ cells/mL) was able to degrade patulin from 20 μg/mL to an undetectable level in 72 h. The RNA-seq data showed patulin-induced oxidative stress and responses in P. caribbica. The deletion of PcCRG1 led to a significant decrease in patulin degradation by P. caribbica, whereas the overexpression of PcCRG1 accelerated the degradation of patulin. The study identified that PcCRG1 protein had the ability to degrade patulin in vitro. Overall, we demonstrated that the patulin degradation process in P. caribbica was more than one way; PcCRG1 was an S-adenosylmethionine-dependent methyltransferase and played an important role in the patulin degradation process in P. caribbica.

Patulin in Apples and Apple-Based Food Products: The Burdens and the Mitigation Strategies

Apples and apple-based products are among the most popular foods around the world for their delightful flavors and health benefits. However, the commonly found mold, Penicillium expansum invades wounded apples, causing the blue mold decay and ensuing the production of patulin, a mycotoxin that negatively affects human health. Patulin contamination in apple products has been a worldwide problem without a satisfactory solution yet. A comprehensive understanding of the factors and challenges associated with patulin accumulation in apples is essential for finding such a solution. This review will discuss the effects of the pathogenicity of Penicillium species, quality traits of apple cultivars, and environmental conditions on the severity of apple blue mold and patulin contamination. Moreover, beyond the complicated interactions of the three aforementioned factors, patulin control is also challenged by the lack of reliable detection methods in food matrices, as well as unclear degradation mechanisms and limited knowledge about the toxicities of the metabolites resulting from the degradations. As apple-based products are mainly produced with stored apples, pre- and post-harvest strategies are equally important for patulin mitigation. Before storage, disease-resistance breeding, orchard-management, and elicitor(s) application help control the patulin level by improving the storage qualities of apples and lowering fruit rot severity. From storage to processing, patulin mitigation strategies could benefit from the optimization of apple storage conditions, the elimination of rotten apples, and the safe and effective detoxification or biodegradation of patulin.

The Response of Rhodotorula mucilaginosa to Patulin Based on Lysine Crotonylation

Patulin (PAT) is a mycotoxin produced by some Penicillium, Aspergillus, and Byssochlamys species. Rhodotorula mucilaginosa is able to degrade PAT in vivo as well as in vitro, up till date, the process and molecular mechanism(s) involved patulin degradation still remains unknown. Protein lysine crotonylation (Kcr) plays an important role in regulating chromatin dynamics, gene expression, and metabolic pathways in mammals and eukaryotes. Investigation of the Kcr changes accompanying degradation of patulin in R. mucilaginosa were observed to investigate the mechanisms of patulin inhibition. Tandem mass tag (TMT) labeling and Kcro affinity enrichment, followed by high-resolution LC-MS/MS analysis, were used to perform quantitative lysine crotonylome analysis on R. mucilaginosa. Consequently, 1691 lysine crotonylation sites in 629 protein groups were identified, among which we quantified 1457 sites in 562 proteins. Among the quantified proteins, 79 and 46 crotonylated proteins were up-regulated and down-regulated, respectively. The differentially up expressed modified proteins were mainly involved in tricarboxylic acid cycle and gluconeogenic pathway. The differentially down expressed Kcr proteins were mainly classified to ribosome and carbohydrate transport and metabolism. Bioinformatic analyses were performed to annotate the quantifiable lysine crotonylated targets. Moreover, interaction networks and high confidence domain architectures of crotonylated proteins were investigated with the aid of bioinformatic tools, and these results showed that there was an increase in the number of yeasts with crotonylated proteins. The results also provided information on the various roles of crotonylation, which are involved in PAT degradation.

Crosstalk between proteins expression and lysine acetylation in response to patulin stress in Rhodotorula mucilaginosa

The proteomic and lysine acetylation (Kac) changes, accompanying degradation of patulin in Rhodotorula mucilaginosa were analyzed using tandem mass tagging and N6-acetyllysine affinity enrichment followed by LC-MS/MS. Proteomic results showed that expression level of short-chain reductase protein and glutathione S-transferase involved in detoxification was significantly up-regulated. In addition, the expression levels of zinc-binding oxidoreductase and quinone oxidoreductase that are involved in antioxidant process, ABC transport and MFS transport responsible for chemical transport were activated when treated with patulin. The quantitative real time PCR (qRT-PCR) result also indicated these genes expression levels were increased when treated with patulin. Kac changes accompanying degradation of patulin in R. mucilaginosa were also observed. Totally, 130 Kac sites in 103 proteins were differentially expressed under patulin stress. The differentially up expressed modified proteins were mainly involved in tricarboxylic acid cycle and nuclear acid biosynthesis. The differentially down expressed Kac proteins were mainly classified to ribosome, oxidative phosphorylation, protein synthesis and defense to stress process. Our results suggest that patulin exposure prompt R. mucilaginosa to produce a series of actions to resist or degrade patulin, including Kac. In addition, the Kac information in R. mucilaginosa and Kac in response to patulin stress was firstly revealed.

Patulin Induced Oxidative Stress Mediated Apoptotic Damage in Mice, and its Modulation by Green Tea Leaves

BACKGROUND

The present study demonstrates the antioxidant and hepatic protective effects of Green tea leaves (GTL).

METHODS

The serum level of aspartate aminotransferase and alanine aminotransferase was analyzed. The liver antioxidant enzymes such as SOD, CAT, GPx, GR, GSH, lipid peroxidation and protein carbonyls, ROS content were estimated. The histology of liver tissue was observed and the protein expression of SOD, CAT, Caspase-3 and p53 was investigated by Western blotting.

RESULTS

Effectiveness of GTL extract in preventing patulin induced liver damage showed significant reduction in serum ALT and AST to 19% and 85% respectively, the increase in antioxidant levels and lipid peroxidation products with patulin treatment were also reduced with GTL supplementation. The patulin induced increase in hepatic protein carbonyls was significantly reduced by 141-111% with 100 and 200 mg/kg b.wt GTL and in ROS was significantly reduced by 171-140% with 100 and 200 mg/kg b.wt GTL administration respectively. Also showed protection against hepatic tissue damage and protein expression in mice.

CONCLUSION

This study showed remarkable antioxidant and hepatic protective effects of GTL.

Biodegradation Mechanisms of Patulin in Candida guilliermondii: An iTRAQ-Based Proteomic Analysis

Patulin, a potent mycotoxin, contaminates fruits and derived products worldwide, and is a serious health concern. Several yeast strains have shown the ability to effectively degrade patulin. However, the mechanisms of its biodegradation still remain unclear at this time. In the present study, biodegradation and involved mechanisms of patulin by an antagonistic yeast Candida guilliermondii were investigated. The results indicated that C. guilliermondii was capable of not only multiplying to a high population in medium containing patulin, but also effectively reducing patulin content in culture medium. Degradation of patulin by C. guilliermondii was dependent on the yeast cell viability, and mainly occurred inside cells. E-ascladiol was the main degradation product of patulin. An iTRAQ-based proteomic analysis revealed that the responses of C. guilliermondii to patulin were complex. A total of 30 differential proteins involved in 10 biological processes were identified, and more than two-thirds of the differential proteins were down-accumulated. Notably, a short-chain dehydrogenase (gi|190348612) was markedly induced by patulin at both the protein and mRNA levels. Our findings will provide a foundation to help enable the commercial development of an enzyme formulation for the detoxification of patulin in fruit-derived products.

Transcriptomic responses of the basidiomycete yeast Sporobolomyces sp. to the mycotoxin patulin

BACKGROUND

Patulin is a mycotoxin produced by Penicillium expansum, the causal agent of blue mold of stored pome fruits, and several other species of filamentous fungi. This mycotoxin has genotoxic, teratogenic and immunotoxic effects in mammals, and its presence in pome fruits and derived products represents a serious health hazard. Biocontrol agents in the Pucciniomycotina, such as the yeasts Sporobolomyces sp. strain IAM 13481 and Rhodosporidium kratochvilovae strain LS11, are able to resist patulin and degrade it into the less toxic compounds desoxypatulinic acid and ascladiol.

RESULTS

In this investigation we applied a transcriptomic approach based on RNAseq to annotate the genome of Sporobolomyces sp. IAM 13481 and then study the changes of gene expression in Sporobolomyces sp. exposed to patulin. Patulin treatment leads to ROS production and oxidative stress that result in the activation of stress response mechanisms controlled by transcription factors. Upregulated Sporobolomyces genes were those involved in oxidation-reduction and transport processes, suggesting the activation of defense mechanisms to resist patulin toxicity and expel the mycotoxin out of the cells. Other upregulated genes encoded proteins involved in metabolic processes such as those of the glutathione and thioredoxin systems, which are essential to restore the cellular redox homeostasis. Conversely, patulin treatment decreased the expression of genes involved in the processes of protein synthesis and modification, such as transcription, RNA processing, translation, protein phosphorylation and biosynthesis of amino acids. Also, genes encoding proteins involved in transport of ions, cell division and cell cycle were downregulated. This indicates a reduction of metabolic activity, probably due to the high energy requirement by the cells or metabolic arrest while recovering from the insult caused by patulin toxicity.

CONCLUSIONS

Complex mechanisms are activated in a biocontrol yeast in response to patulin. The genes identified in this study can pave the way to develop i) a biodetoxification process of patulin in juices and ii) a biosensor for the rapid and cost-effective detection of this mycotoxin.

Regulation of the antioxidant system in cells of the fission yeast Schizosaccharomyces pombe after combined treatment with patulin and citrinin

The effects of combined treatment with patulin (PAT) and citrinin (CTN) on Schizosaccharomyces pombe cells were investigated in acute toxicity tests. In comparison with the controls the exposure of fission yeast cells (10(7) cells ml(-1)) to PAT + CTN (250 μM each) for 1 h at a survival rate of 66.6% significantly elevated the concentration of total reactive oxygen species (ROS) via increased levels of peroxides without affecting the concentrations of superoxides or the hydroxyl radical. This treatment induced a 3.08-fold increase in the specific concentration of glutathione and elevated specific activities of catalase and glutathione S-transferase, while at the same time the activity of glutathione reductase decreased. The pattern of the ROS was the same as that induced by CTN (Máté et al., 2014), while the presence of PAT in the PAT + CTN combination treatment modified the activities of the antioxidant system (Papp et al., 2012) in comparison with the individual PAT or CTN treatment, suggesting toxin-specific regulation of glutathione and the enzymes of the antioxidant system and the possibility that the transcription factor (pap1 and atf1) -regulated processes might be influenced directly by ROS.

Core oxidative stress response in Aspergillus nidulans

BACKGROUND

The b-Zip transcription factor AtfA plays a key role in regulating stress responses in the filamentous fungus Aspergillus nidulans. To identify the core regulons of AtfA, we examined genome-wide expression changes caused by various stresses in the presence/absence of AtfA using A. nidulans microarrays. We also intended to address the intriguing question regarding the existence of core environmental stress response in this important model eukaryote.

RESULTS

Examination of the genome wide expression changes caused by five different oxidative stress conditions in wild type and the atfA null mutant has identified a significant number of stereotypically regulated genes (Core Oxidative Stress Response genes). The deletion of atfA increased the oxidative stress sensitivity of A. nidulans and affected mRNA accumulation of several genes under both unstressed and stressed conditions. The numbers of genes under the AtfA control appear to be specific to a stress-type. We also found that both oxidative and salt stresses induced expression of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of additional clusters. Moreover, certain clusters were down-regulated by the stresses tested.

CONCLUSION

Our data suggest that the observed co-regulations were most likely consequences of the overlapping physiological effects of the stressors and not of the existence of a general environmental stress response. The function of AtfA in governing various stress responses is much smaller than anticipated and/or other regulators may play a redundant or overlapping role with AtfA. Both stress inducible and stress repressive regulations of secondary metabolism seem to be frequent features in A. nidulans.

Cuscuta chinensis seeds water extraction protecting murine osteoblastic MC3T3-E1 cells against tertiary butyl hydroperoxide induced injury

ETHNOPHARMACOLOGICAL RELEVANCE

Cuscuta chinensis (C. chinensis) is a well-known traditional Chinese herb that has been used to treat heart disease, diabetes, liver injury, cancer, and aging.

MATERIALS AND METHODS

Murine osteoblastic MC3T3-E1 cells were treated with various concentrations of C. chinensis water extraction at different time intervals. The antioxidant effect of C. chinensis on MC3T3-E1 cells was evaluated using MTT and TUNEL assays. The effect of C. chinensis on cell cycle was analyzed by flow cytometry with propidium iodide. Lipid peroxidation was measured by the HPLC method. The cellular redox status was determined from the reduced glutathione to oxidized glutathione ratio (GSH/GSSG) and the enzymes involved in glutathione metabolism, including glutathione reductase (GR), Glutathione S-transferase (GST), and Glucose-6-phosphate dehydrogenase (G6PD). The changes in relative mitochondrial transmembrane potential (ΔΨm) in the MC3T3-E1 cells were analyzed with rhodamine 123 staining. Western blot analysis was used to evaluate the levels of cytochrome c (cyto c), Bax, Bcl-2, caspase 3, Sirt3, and IDH2 expressions.

RESULTS

The C. chinensis water extraction protects tertiary butyl hydroperoxide (TBHP)-treated MC3T3-E1 cells from death in a dose-dependent manner. C. chinensis treatment significantly inhibited the reactive oxygen species (ROS) generation, malondialdehyde (MDA) production, and increased the activity of superoxide dismutase (SOD), GR, GST, and G6PD. The release of cyto c from mitochondria was reduced by C. chinensis, which increased the expression of antiapoptotic IDH2, Sirt3, and Bcl-2 and decreased the expression of Bax, cyto c, and caspase 3.

CONCLUSIONS

C. chinensis modulated the oxidative stress-induced apoptosis in MC3T3-E1 cells, probably due to its antioxidant activity and functioning via mitochondria-dependent pathways.