Peroxiredoxin 1 (Prx1) is a dual-function enzyme by possessing Cys-independent catalase-like activity

Metabolomics and Transcriptomics Reveal the Effects of Different Fermentation Times on Antioxidant Activities of Ophiocordyceps sinensis

Ophiocordyceps sinensis is a fungus that is cultured through fermentation from wild Chinese cordyceps. While studies have examined its metabolites, the evaluation of its antioxidant capacity remains to be conducted. The antioxidant results of O. sinensis indicate that the ferric ion-reducing antioxidant power (FRAP), antioxidant capacity (2.74 ± 0.12 μmol Trolox/g), 2,2-diphenyl-1-picrylhydrazyl (DPPH•) free radical scavenging rate (60.21 ± 0.51%), and the hydroxyl free radical scavenging rate (91.83 ± 0.68%) reached a maximum on day 30. Using LC-MS/MS to measure the metabolites on D24, D30, and D36, we found that the majority of the differential accumulated metabolites (DAMs) primarily accumulate in lipids, organoheterocyclic compounds, and organic acids and their derivatives. Notably, the DAMs exhibiting high peaks include acetylcarnitine, glutathione, linoleic acid, and L-propionylcarnitine, among others. The transcriptome analysis results indicate that the differentially expressed genes (DEGs) exhibiting high expression peaks on D30 primarily included lnaA, af470, and ZEB1; high expression peaks on D24 comprised SPBC29A3.09c and YBT1; high expression peaks on D36 included dtxS1, PA1538, and katG. The combined analysis revealed significant and extremely significant positive and negative correlations between all the DAMs and DEGs. The primary enriched pathways (p < 0.05) included glutathione metabolism, tryptophan metabolism, carbon metabolism, biosynthesis of secondary metabolites, and phenylalanine metabolism. The metabolic pathway map revealed that the DAMs and DEGs influencing the antioxidant activity of O. sinensis were significantly up-regulated on D30 but down-regulated on D36. The correlation analysis suggests that an increase in the content of DEGs and DAMs promotes an increase in the levels of enzyme and non-enzyme substances, ultimately enhancing the antioxidant capacity of O. sinensis. These findings serve as a reference of how DAMs and DEGs affect the antioxidant activity of O. sinensis. This may contribute to the enhanced development and application of O. sinensis.

Cold-adapted characteristics and gene knockout of alkyl hydroperoxide reductase subunit C in Antarctic Psychrobacter sp. ANT206

Alkyl hydroperoxide reductase subunit C (AhpC) contributes to the cellular defense against reactive oxygen species. However, it remains understudied in psychrophiles. Amino acid comparison demonstrated that AhpC from Psychrobacter sp. ANT206 (ANT206) (PsAhpC) revealed fewer numbers of Lys and more numbers of Gly, which might have favored higher flexibility at low temperature. The recombinant PsAhpC (rPsAhpC) was most active at 25 °C and retained 35% of its residual activity at 0 °C, indicating that it was a cold-adapted enzyme. Additionally, rPsAhpC demonstrated significant salt tolerance, sustaining its activity in the presence of 4.0 M NaCl. Molecular dynamics simulations indicated that PsAhpC had comparatively loose conformation, which facilitated reactions at low temperatures. Subsequently, an ahpc knockout mutant was constructed, and the growth rate of the knockout mutant significantly decreased, suggesting that ahpc might be crucial for the growth of ANT206 at low temperatures. The findings provide a robust foundation for further investigation into the structural features and catalytic characterization of cold-adapted AhpC. The structural characteristics of PsAhpC and its cold tolerance and salt tolerance may be applied to stress resistance breeding of various organisms.

Recent Progress on Peroxidase Modification and Application

Peroxdiase is one of the member of oxireductase super family, which has a broad substrate range and a variety of reaction types, including hydroxylation, epoxidation or halogenation of unactivated C-H bonds, and aromatic group or biophenol compounds. Here, we summarized the recently discovered enzymes with peroxidation activity, and focused on the special structures, sites, and corresponding strategies that can change the peroxidase catalytic activity, stability, and substrate range. The comparison of the structural differences between these natural enzymes and the mimic enzymes of binding nanomaterials and polymer materials is helpful to expand the application of peroxidase in industry. In addition, we also reviewed the catalytic application of peroxidase in the synthesis of important organic molecules and the degradation of pollutants.

Molecular characterization, immune functions and DNA protective effects of peroxiredoxin-1 gene in Antheraea pernyi

Peroxiredoxins are antioxidant proteins that detoxify peroxynitrite, hydrogen peroxide, and organic hydroperoxides, impacting various physiological processes such as immune responses, apoptosis, cellular homeostasis, and so on. In the present study, we identified and characterized peroxiredoxin 1 from Antheraea pernyi (thereafter designated as ApPrx-1) that encodes a predicted 195 amino acid residue protein with a 21.8 kDa molecular weight. Quantitative real-time PCR analysis revealed that the mRNA level of ApPrx-1 was highest in the hemocyte, fat body, and midgut. Immune-challenged larval fat bodies and hemocytes showed increased ApPrx-1 transcript. Moreover, ApPrx-1 expression was induced in hemocytes and the whole body of A. pernyi following exogenous H2O2 administration. A DNA cleavage assay performed using recombinant ApPrx-1 protein showed that rApPrx-1 protein manifests the ability to protect supercoiled DNA damage from oxidative stress. To test the rApPrx-1 protein antioxidant activity, the ability of the rApPrx-1 protein to remove H2O2 was assessed in vitro using rApPrx-1 protein and DTT, while BSA + DDT served as a control group. The results revealed that ApPrx-1 can efficiently remove H2O2 in vitro. In the loss of function analysis, we found that ApPrx-1 significantly increased the levels of H2O2 in ApPrx-1-depleted larvae compared to the control group. We also found a significantly lower survival rate in the larvae in which ApPrx-1 was knocked down. Interestingly, the antibacterial activity was significantly higher in the ApPrx-1 depleted larvae, compared to the control. Collectively, evidence strongly suggests that ApPrx-1 may regulate physiological activities and provides a reference for further studies to validate the utility of the key genes involved in reliving oxidative stress conditions and regulating the immune responses of insects.

Conditional knockout mouse model reveals a critical role of peroxiredoxin 1 in oral leukoplakia carcinogenesis

Peroxiredoxin 1 (Prx1) is an antioxidant protein that may promote the carcinogenesis in oral leukoplakia (OLK). To investigate the effect of Prx1 on the oral mucosal epithelium of OLK, we generated a Prx1 conditional knockout (cKO) mouse model. The mRNA and gRNA were generated using the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) technique. An infusion cloning method was used to construct a homologous recombination vector. To obtain the F0 generation mice, fertilized eggs of C57BL/6J mice were microinjected with Cas9 mRNA, gRNA, and a donor vector. Polymerase chain reaction (PCR) amplification and sequencing were used to identify F1 generation mice. Using the cyclization recombination-enzyme-locus of the X-overP1 (Cre-loxP) system, we created a Prx1 cKO mouse model, and the effectiveness of the knockout was confirmed through immunohistochemistry. We examined the influence of Prx1 knockout on the occurrence of OLK in mice by constructing a model of tongue mucosa carcinogenesis induced by 4-nitroquinoline-1-oxide (4NQO). Prx1 modification was present in the F1 generation, as evidenced by PCR amplification and sequencing. Prx1flox/flox: Cre + mice exhibited normal growth and fertility. Immunohistochemical analysis revealed that tongue epithelial cells in Prx1flox/flox: Cre + mice displayed a distinct deletion of Prx1. An examination of the heart, liver, spleen, lung, and kidney tissues revealed no visible histological changes. Histological analysis showed a reduction in the occurrence of the malignant transformation of OLK in the tongue tissues of Prx1flox/flox: Cre + mice. Ki67 immunostaining showed that Prx1 knockout significantly inhibited cell proliferation in the tongue epithelial. Our research developed a conditional knockout mouse model for Prx1. The obtained results provide insights into the function of Prx1 in the development of oral cancer and emphasize its potential as a therapeutic target for precancerous oral lesions.

Molecular characterization and functional analysis of peroxiredoxin 1 (Prx1) from roughskin sculpin (Trachidermus fasciatus)

Peroxiredoxin1(Prx1), also known as natural killer enhancing factor A (NKEF-A), is a crucial antioxidant involving in various cellular activities and immune response against bacterial and viral infection in fish. In the present study, a full-length Prx1 cDNA sequence (TfPrx1) was firstly cloned from roughskin sculpin (Trachidermus fasciatus), which was composed of 1044 bp nucleotides encoding a peptide of 199 amino acids with a molecular weight of 22.35 kDa and a theoretical pI of 6.42, respectively. The predicted peptide was a typical 2-cys Prx containing two conserved characteristic motifs 43FYPLDFTFVCPTEI56 and 170GEVCPA175 with the two conserved peroxidatic and resolving cysteine residuals forming disulfide bond. Quantitative real-time PCR analysis showed that TfPrx1 was ubiquitously expressed in all tested tissues with the highest expression in the intestine. It could be significantly induced following LPS injection and heavy metal exposure. Recombinant TfPrx1 (rTfPrx1) displayed insulin disulfide reduction and ROS-scavenging activity in a concentration-dependent manner, and further exhibited DNA and cytoprotective effects under oxidative stress. These results suggested that TfPrx1 protein may play an important role in fish immune protection from oxidative damage.

Peroxiredoxin-2 gene in Antheraea pernyi modulates immune functions and protect DNA damage

Peroxiredoxins have been shown to protect insects from oxidative damage and to play a role in the immune system. In the present study, we cloned and characterized the Antheraea pernyi peroxiredoxin 2 (ApPrx-2) gene, then assessed its functional roles. The ApPrx-2 gene has a 687 bp open reading frame that encodes a protein with 288 amino acid residues. Quantitative real-time PCR analysis revealed that the mRNA levels of ApPrx-2 were highest in the hemocytes. Immune challenge assay revealed that ApPrx-2 transcription could be induced after microbial challenge. A DNA cleavage assay employing recombinant ApPrx-2 protein and a metal-catalyzed oxidation system showed that rApPrx-2 protein could protect supercoiled DNA against oxidative stress. The protein antioxidant activity of rApPrx-2 was examined, and it was found that rApPrx-2 exhibited a high level of antioxidant activity by removing H2O2. In addition, ApPrx-2 knockdown larvae had higher H2O2 levels and a lower survival rate when compared to controls. Interestingly, the antibacterial activity was significantly higher in ApPrx-2 depleted larvae compared with control. Overall, our findings indicate that ApPrx-2 may be involved in a range of physiological functions of A. pernyi, as it protects supercoiled DNA from oxidative stress and regulates antibacterial activity.

Antifungal Peptide P852 Effectively Controls Fusarium oxysporum, a Wilt-Causing Fungus, by Affecting the Glucose Metabolism and Amino Acid Metabolism as well as Damaging Mitochondrial Function

Fusarium oxysporum causes wilt disease, which causes huge economic losses to a wide range of agricultural cash crops. Antifungal peptide P852 is an effective biocide. However, the mechanism of direct inhibition of pathogenic fungus needs to be explored. The proteomics and transcriptomics results showed that P852 mainly affected intracellular pathways such as glucose metabolism, amino acid metabolism, and oxidoreductase activity in F. oxysporum. P852 disrupts the intracellular oxidative equilibrium in F. oxysporum, and transmission electron microscopy observed mitochondrial swelling, disruption of membrane structure, and leakage of contents. Decreased mitochondrial membrane potential, mitochondrial cytochrome c leakage, and reduced ATP production were also detected. These results suggest that P852 is able to simultaneously inhibit intracellular metabolism and disrupt the mitochondrial function of F. oxysporum, exerting its inhibitory effects in multiple pathways together. The present study provides some insights into the multitargeted mechanism of fungus inhibition of antifungal lipopeptide substances produced by Bacillus spp.

Silica-Calcium-Alginate Hydrogels for the Co-Immobilization of Glucose Oxidase and Catalase to Reduce the Glucose in Grape Must

Higher temperatures due to climate change are causing greater sugar production in grapes and more alcoholic wines. The use of glucose oxidase (GOX) and catalase (CAT) in grape must is a biotechnological green strategy to produce reduced-alcohol wines. GOX and CAT were effectively co-immobilized by sol-gel entrapment in silica-calcium-alginate hydrogel capsules. The optimal co-immobilization conditions were achieved at a concentration of the colloidal silica, sodium silicate and sodium alginate of 7.38%, 0.49% and 1.51%, respectively, at pH 6.57. The formation of a porous silica-calcium-alginate structure was confirmed by environmental scanning electron microscopy and the elemental analysis of the hydrogel by X-ray spectroscopy. The immobilized GOX showed a Michaelis-Menten kinetic, while the immobilized CAT fits better to an allosteric model. Immobilization also conferred superior GOX activity at low pH and temperature. The capsules showed a good operational stability, as they could be reused for at least 8 cycles. A substantial reduction of 26.3 g/L of glucose was achieved with encapsulated enzymes, which corresponds to a decrease in potential alcoholic strength of must of about 1.5% vol. These results show that co-immobilized GOX and CAT in silica-calcium-alginate hydrogels is a promising strategy to produce reduced-alcohol wines.

Identification of Mycoparasitism-Related Genes against the Phytopathogen Botrytis cinerea via Transcriptome Analysis of Trichoderma harzianum T4

Trichoderma harzianum is a well-known biological control agent (BCA) that is effective against a variety of plant pathogens. In previous studies, we found that T. harzianum T4 could effectively control the gray mold in tomatoes caused by Botrytis cinerea. However, the research on its biocontrol mechanism is not comprehensive, particularly regarding the mechanism of mycoparasitism. In this study, in order to further investigate the mycoparasitism mechanism of T. harzianum T4, transcriptomic sequencing and real-time fluorescence quantitative PCR (RT-qPCR) were used to identify the differentially expressed genes (DEGs) of T. harzianum T4 at 12, 24, 48 and 72 h of growth in the cell wall of B. cinerea (BCCW) or a sucrose medium. A total of 2871 DEGs and 2148 novel genes were detected using transcriptome sequencing. Through GO and KEGG enrichment analysis, we identified genes associated with mycoparasitism at specific time periods, such as encoding kinases, signal transduction proteins, carbohydrate active enzymes, hydrolytic enzymes, transporters, antioxidant enzymes, secondary metabolite synthesis, resistance proteins, detoxification genes and genes associated with extended hyphal longevity. To validate the transcriptome data, RT-qCPR was performed on the transcriptome samples. The RT-qPCR results show that the expression trend of the genes was consistent with the RNA-Seq data. In order to validate the screened genes associated with mycoparasitism, we performed a dual-culture antagonism test on T. harzianum and B. cinerea. The results of the dual-culture RT-qPCR showed that 15 of the 24 genes were upregulated during and after contact between T. harzianum T4 and B. cinerea (the same as BCCW), which further confirmed that these genes were involved in the mycoparasitism of T. harzianum T4. In conclusion, the transcriptome data provided in this study will not only improve the annotation information of gene models in T. harzianum T4 genome, but also provide important transcriptome information regarding the process of mycoparasitism at specific time periods, which can help us to further understand the mechanism of mycoparasitism, thus providing a potential molecular target for T. harzianum T4 as a biological control agent.

Molecular characterization, immune expression, and functional delineation of peroxiredoxin 1 in Epinephelus akaara

Peroxiredoxin 1 is a member of the typical 2-Cys peroxiredoxin family, which serves diverse functions in gene expression, immune and inflammatory responses, and tumor progression. In this study, we aimed to analyze the structural, functional, and immunomodulatory properties of peroxiredoxin 1 from Epinephelus akaara (EaPrx1). The open reading frame of EaPrx1 is 597 base pairs in length, encoding 198 amino acids, with a molecular weight of approximately 22 kDa. The in silico analysis revealed that EaPrx1 shares a conserved thioredoxin fold and signature motifs that are critical for its catalytic activity and oligomerization. Further, EaPrx1 is closely related to Epinephelus lanceolatus Prx1 and clustered in the Fishes group of the vertebrate clade, revealing that EaPrx1 was conserved throughout evolution. In terms of tissue distribution, a high level of EaPrx1 expression was observed in the spleen, brain, and blood tissues. Likewise, in immune challenge experiments, significant transcriptional modulations of EaPrx1 upon lipopolysaccharide, polyinosinic:polycytidylic acid, and nervous necrosis virus injections were noted at different time points, indicating the immunological role of EaPrx1 against pathogenic infections. In the functional analysis, rEaPrx1 exhibited substantial DNA protection, insulin disulfide reduction, and tissue repair activities, which were concentration-dependent. EaPrx1/pcDNA™ 3.1 (+)-transfected fathead minnow cells revealed high cell viability upon arsenic toxicity, indicating the heavy metal detoxification activity of EaPrx1. Taken together, the transcriptional and functional studies imply critical roles of EaPrx1 in innate immunity, redox regulation, apoptosis, and tissue-repair processes in E. akaara.

Molecular Characterization of a New Tetrodotoxin-Binding Protein, Peroxiredoxin-1, from Takifugu bimaculatus

Pufferfish are considered a culinary delicacy but require careful preparation to avoid ingestion of the highly toxic tetrodotoxin (TTX), which accumulates in certain tissues. In this study, the tissue distribution of peroxiredoxin-1 from Takifugu bimaculatus was investigated. The peroxiredoxin-1 protein was obtained by in vitro recombinant expression and purification. The recombinant protein had a strong ability to scavenge hydroxyl radicals, protect superhelical DNA plasmids from oxidative damage, and protect L929 cells from H₂O₂ toxicity through in vitro antioxidant activity. In addition, we verified its ability to bind to tetrodotoxin using surface plasmon resonance techniques. Further, recombinant proteins were found to facilitate the entry of tetrodotoxin into cells. Through these analyses, we identified, for the first time, peroxiredoxin-1 protein from Takifugu bimaculatus as a potential novel tetrodotoxin-binding protein. Our findings provide a basis for further exploration of the application of peroxiredoxin-1 protein and the molecular mechanisms of tetrodotoxin enrichment in pufferfish.

Intertwined associations between oxidative and nitrosative stress and endocannabinoid system pathways: Relevance for neuropsychiatric disorders

The endocannabinoid system (ECS) appears to regulate metabolic, cardiovascular, immune, gastrointestinal, lung, and reproductive system functions, as well as the central nervous system. There is also evidence that neuropsychiatric disorders are associated with ECS abnormalities as well as oxidative and nitrosative stress pathways. The goal of this mechanistic review is to investigate the mechanisms underlying the ECS's regulation of redox signalling, as well as the mechanisms by which activated oxidative and nitrosative stress pathways may impair ECS-mediated signalling. Cannabinoid receptor (CB)1 activation and upregulation of brain CB2 receptors reduce oxidative stress in the brain, resulting in less tissue damage and less neuroinflammation. Chronically high levels of oxidative stress may impair CB1 and CB2 receptor activity. CB1 activation in peripheral cells increases nitrosative stress and inducible nitric oxide (iNOS) activity, reducing mitochondrial activity. Upregulation of CB2 in the peripheral and central nervous systems may reduce iNOS, nitrosative stress, and neuroinflammation. Nitrosative stress may have an impact on CB1 and CB2-mediated signalling. Peripheral immune activation, which frequently occurs in response to nitro-oxidative stress, may result in increased expression of CB2 receptors on T and B lymphocytes, dendritic cells, and macrophages, reducing the production of inflammatory products and limiting the duration and intensity of the immune and oxidative stress response. In conclusion, high levels of oxidative and nitrosative stress may compromise or even abolish ECS-mediated redox pathway regulation. Future research in neuropsychiatric disorders like mood disorders and deficit schizophrenia should explore abnormalities in these intertwined signalling pathways.

A Large-Scale Multiple Genome Comparison of Acidophilic Archaea (pH ≤ 5.0) Extends Our Understanding of Oxidative Stress Responses in Polyextreme Environments

Acidophilic archaea thrive in anaerobic and aerobic low pH environments (pH < 5) rich in dissolved heavy metals that exacerbate stress caused by the production of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), hydroxyl radical (OH) and superoxide (O2−). ROS react with lipids, proteins and nucleic acids causing oxidative stress and damage that can lead to cell death. Herein, genes and mechanisms potentially involved in ROS mitigation are predicted in over 200 genomes of acidophilic archaea with sequenced genomes. These organisms are often be subjected to simultaneous multiple stresses such as high temperature, high salinity, low pH and high heavy metal loads. Some of the topics addressed include: (1) the phylogenomic distribution of these genes and what this can tell us about the evolution of these mechanisms in acidophilic archaea; (2) key differences in genes and mechanisms used by acidophilic versus non-acidophilic archaea and between acidophilic archaea and acidophilic bacteria and (3) how comparative genomic analysis predicts novel genes or pathways involved in oxidative stress responses in archaea and likely horizontal gene transfer (HGT) events.

Assessment of Potential Prognostic Value of Peroxiredoxin 1 in Oral Squamous Cell Carcinoma

Purpose

The role of the peroxiredoxin (PRDX) family in oral squamous cell carcinoma (OSCC) remains unclear. This study aimed to investigate the expression of PRDXs and their effects on the prognosis in OSCC.

Methods

The expression of PRDXs and their effects on prognosis were analysed in 216 OSCC samples from The Cancer Genome Atlas (TCGA) database. OSCC tissues and adjacent noncancerous tissues (ANTs) were obtained from 68 clinical patients. Quantitative real-time (qRT)-PCR, Western blot, and immunohistochemical (IHC) staining were used to verify the relationship between the expression level of PRDX1 and different clinical features. Gene set enrichment analysis (GSEA) was used to examine the molecular mechanism of PRDX1 in OSCC.

Results

PRDX1 was found to be the only gene in PRDX family that highly expressed in OSCC samples and affected the prognosis of patients with OSCC. PRDX1 expression was significantly related to tumor stage, lymphatic metastasis, and pathological grade. A nomogram consisting of tumor stage, N stage, and PRDX1 level was constructed. GSEA showed that high expression of PRDX1 involved many cancer-related molecular functions and signaling pathways.

Conclusion

PRDX1 may play an important role in the occurrence and development of OSCC, and may be a potential new target for OSCC treatment.

Tandem Mass Tag-Based Quantitative Proteomic Analysis of Chicken Bursa of Fabricius Infected With Reticuloendotheliosis Virus

Reticuloendotheliosis virus (REV) is a type C avian retrovirus that causes immunosuppression, dwarf syndrome, and lymphoma in infected hosts. In this study, we used tandem mass tag (TMT) labeling and liquid chromatography–tandem mass spectrometry (LC-MS/MS) to characterize protein alterations in chicken bursa of Fabricius, before and after REV infection at 7, 14, 21, and 28 days. Our data showed that 1,127, 999, 910, and 1,138 differentially expressed proteins were significantly altered at 7, 14, 21, and 28 days after REV infection, respectively. Morphological analysis showed that REV infection reduced in cortical lymphocytes, bursal follicle atrophy, and nuclear damage. Bioinformatics analysis indicated these proteins were mainly involved with immune responses, energy metabolism, cellular processes, biological regulation, metabolic processes, response to stimuli, and multicellular organismal process. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway cluster analysis showed that post-infection, proteins were enriched in the cell cycle, Wnt signaling, antigen processing and presentation, cytokine receptor interaction, adenosine 3′,5′-cyclic monophosphate signaling pathway, and NF-κB signaling. In addition, we observed that peroxiredoxin 4 (PRDX4), peroxiredoxin 6 (PRDX6), glutathione peroxidase 3 (GPX3), catalase (CAT), and peroxidasin (PXDN) were involved in oxidative stress. Some heat shock protein (HSP) family members such as HSPH1, DNAJA4, HSPA8, and HSPA4L also changed significantly after REV infection. These findings help clarify interactions between REV and the host and provides mechanistic insights on REV-induced host immunosuppression.

Epo-C12 inhibits peroxiredoxin 1 peroxidase activity

Epo-C12 is a synthetic derivative of epolactaene, isolated from Penicillium sp. BM 1689-P. Epo-C12 induces apoptosis in human acute lymphoblastoid leukemia BALL-1 cells. In our previous studies, seven proteins that bind to Epo-C12 were identified by a combination of pull-down experiments using biotinylated Epo-C12 (Bio-Epo-C12) and mass spectrometry. In the present study, the effect of Epo-C12 on peroxiredoxin 1 (Prx 1), one of the proteins that binds to Epo-C12, was investigated. Epo-C12 inhibited Prx 1 peroxidase activity. However, it did not suppress its chaperone activity. Binding experiments between Bio-Epo-C12 and point-mutated Prx 1s suggest that Epo-C12 binds to Cys⁵² and Cys⁸³ in Prx 1. The present study revealed that Prx 1 is one of the target proteins through which Epo-C12 exerts an apoptotic effect in BALL-1 cells.

Transcriptional modifications and the cytoprotective, DNA protective, and wound healing effects of peroxiredoxin-1 from Sebastes schlegelii

Peroxiredoxins are a group of thiol-specific antioxidant proteins that take six isoforms in vertebrates and allow the innate immune system to sense and detoxify reactive oxygen species. In this study, we identified and characterized the perxiredoxin-1 (SsPrdx1) cDNA sequence from the rockfish, Sebastes schlegelii. In silico analysis revealed that SsPrdx1 contained a 594 bp long open reading frame (ORF) encoding a protein of 198 amino acids, with a predicted molecular weight and theoretical isoelectric point of 21.97 kDa and 6.30, respectively. The SsPrdx1 gene comprised six exons linked by five introns, while peroxiredoxin signature motifs were found in the highly conserved third, fourth, and fifth exons. Phylogenetic analysis and sequence alignment suggested that SsPrdx1 is evolutionarily conserved and that its most closely related counterpart is Salarias fasciatus. Recombinant SsPrdx1 (rSsPrdx1) displayed supercoiled DNA protection and insulin disulfide reduction activities in a concentration-dependent manner, while cells transiently transfected with pcDNA3.1 (+)/SsPrdx1 exhibited significant cytoprotective effects under oxidative stress and wound healing activity. SsPrdx1 transcripts were constitutively expressed under normal physiological conditions, with the highest expression observed in the blood. Moreover, SsPrdx1 expression increased in the blood, spleen, and liver following immune provocation by LPS, poly I:C, and Streptococcus iniae injection. Thus, this study provides insights into the role of SsPrdx1 in rockfish immune protection.

Analyses of the expression, immunohistochemical properties and serodiagnostic potential of Schistosoma japonicum peroxiredoxin-4

Background

Schistosoma japonicum, which inhabits the mesenteric vein of the mammalian hosts for about 20 to 30 years, is subjected to the oxidative stresses from the host defense mechanism during their intra-mammalian stages. To counteract this host immune attack, the parasite utilizes their antioxidant system for survival inside the host. Peroxiredoxins (Prxs), thiol-specific antioxidant proteins, play an essential role for protecting the parasite against oxidative stress by reducing hydrogen peroxide to water. Only three types of 2-Cys Prxs have been previously characterized in S. japonicum whereas a fourth Prx has been identified for Schistosoma mansoni as Prx-4. A sequence coding homologous to this gene in the S. japonicum database was identified, characterized and expressed as recombinant SjPrx-4 protein (rSjPrx-4). Furthermore, rSjPrx-4 was evaluated in this study for its diagnostic potentials in detecting S. japonicum infection in humans.

Results

The gene found in the parasite genome contained 2 active-site cysteines with conserved sequences in the predicted amino acid (AA) sequence and showed 75% identity with that of the previously characterized Prx (TPx-1) of S. japonicum. The gene was expressed in different stages of schistosome life-cycle with highest transcription level in the adult male. The gene was cloned into a plasmid vector and then transfected into Escherichia coli for expression of rSjPrx-4. Anti-rSjPrx-4 mouse sera recognized native SjPrx-4 in egg and adult worm lysate by western blotting. The result of a mixed function oxidation assay in which rSjPrx-4 prevented the nicking of DNA from hydroxyl radicals confirmed its antioxidant activity. Subsequently, immunolocalization analysis showed the localization of SjPrx-4 inside the egg, on the tegument and in the parenchyma of the adult worm. Enzyme-linked immunosorbent assay results showed that rSjPrx-4 has 83.3% sensitivity and 87.8% specificity. Its diagnostic potential was further evaluated in combination with recombinant SjTPx-1 protein, yielding an improved sensitivity and specificity of 90% and 92.7%, respectively.

Conclusions

These results suggest that SjPrx-4 plays a role as an antioxidant dealing with oxidative stresses of S. japonicum, and its diagnostic potential improved by coupling it with SjTPx-1 is a proof for developing a serological test with better diagnostic performance for human schistosomiasis.

Uncovering a possible role of reactive oxygen species in magnetogenetics

Recent reports have shown that intracellular, (super)paramagnetic ferritin nanoparticles can gate TRPV1, a non-selective cation channel, in a magnetic field. Here, we report the effects of differing field strength and frequency as well as chemical inhibitors on channel gating using a Ca2+-sensitive promoter to express a secreted embryonic alkaline phosphatase (SEAP) reporter. Exposure of TRPV1-ferritin-expressing HEK-293T cells at 30 °C to an alternating magnetic field of 501 kHz and 27.1 mT significantly increased SEAP secretion by ~ 82% relative to control cells, with lesser effects at other field strengths and frequencies. Between 30-32 °C, SEAP production was strongly potentiated 3.3-fold by the addition of the TRPV1 agonist capsaicin. This potentiation was eliminated by the competitive antagonist AMG-21629, the NADPH oxidase assembly inhibitor apocynin, and the reactive oxygen species (ROS) scavenger N-acetylcysteine, suggesting that ROS contributes to magnetogenetic TRPV1 activation. These results provide a rational basis to address the heretofore unknown mechanism of magnetogenetics.

Plant catalases as NO and H2S targets

Catalase is a powerful antioxidant metalloenzyme located in peroxisomes which also plays a central role in signaling processes under physiological and adverse situations. Whereas animals contain a single catalase gene, in plants this enzyme is encoded by a multigene family providing multiple isoenzymes whose number varies depending on the species, and their expression is regulated according to their tissue/organ distribution and the environmental conditions. This enzyme can be modulated by reactive oxygen and nitrogen species (ROS/RNS) as well as by hydrogen sulfide (H2S). Catalase is the major protein undergoing Tyr-nitration [post-translational modification (PTM) promoted by RNS] during fruit ripening, but the enzyme from diverse sources is also susceptible to undergo other activity-modifying PTMs. Data on S-nitrosation and persulfidation of catalase from different plant origins are given and compared here with results from obese children where S-nitrosation of catalase occurs. The cysteine residues prone to be S-nitrosated in catalase from plants and from bovine liver have been identified. These evidences assign to peroxisomes a crucial statement in the signaling crossroads among relevant molecules (NO and H2S), since catalase is allocated in these organelles. This review depicts a scenario where the regulation of catalase through PTMs, especially S-nitrosation and persulfidation, is highlighted.

The interplay between oxidative stress and bioenergetic failure in neuropsychiatric illnesses: can we explain it and can we treat it?

Nitro-oxidative stress and lowered antioxidant defences play a key role in neuropsychiatric disorders such as major depression, bipolar disorder and schizophrenia. The first part of this paper details mitochondrial antioxidant mechanisms and their importance in reactive oxygen species (ROS) detoxification, including details of NO networks, the roles of H₂O₂ and the thioredoxin/peroxiredoxin system, and the relationship between mitochondrial respiration and NADPH production. The second part highlights and identifies the causes of the multiple pathological sequelae arising from self-amplifying increases in mitochondrial ROS production and bioenergetic failure. Particular attention is paid to NAD⁺ depletion as a core cause of pathology; detrimental effects of raised ROS and reactive nitrogen species on ATP and NADPH generation; detrimental effects of oxidative and nitrosative stress on the glutathione and thioredoxin systems; and the NAD⁺-induced signalling cascade, including the roles of SIRT1, SIRT3, PGC-1α, the FOXO family of transcription factors, Nrf1 and Nrf2. The third part discusses proposed therapeutic interventions aimed at mitigating such pathology, including the use of the NAD⁺ precursors nicotinamide mononucleotide and nicotinamide riboside, both of which rapidly elevate levels of NAD⁺ in the brain and periphery following oral administration; coenzyme Q₁₀ which, when given with the aim of improving mitochondrial function and reducing nitro-oxidative stress in the brain, may be administered via the use of mitoquinone, which is in essence ubiquinone with an attached triphenylphosphonium cation; and N-acetylcysteine, which is associated with improved mitochondrial function in the brain and produces significant decreases in oxidative and nitrosative stress in a dose-dependent manner.

Trxlp, a thioredoxin-like effector from Edwardsiella piscicida inhibits cellular redox signaling and nuclear translocation of NF-κB

Redox signaling and homeostasis are essential for cell survival and the immune response. Peroxiredoxin (Prx) modulates the level of H₂O₂ as a redox signal through H₂O₂ decomposition. The redox activity of thioredoxin (Trx) is required as a reducing equivalent to regenerate Prx. Edwardsiella piscicida is an opportunistic Gram-negative enteric pathogen that secretes a novel Trx-like effector protein, ETAE_2186 (Trxlp). Trxlp has unique structural properties compared with other Trx proteins. In enzymatic and binding assays, we confirmed Trxlp to be redox-inactive due to the low reactivity and flexibility of the resolving cysteine residue, C35, at the active site motif "³¹WCXXC³⁵". We identified key residues near the active site that are critical for reactivity and flexibility of C35 by site-directed mutagenesis analysis. NMR titration experiment demonstrated prolong inhibitory interaction of Trxlp with Prx1 resulting in the repression of Prx1-mediated H₂O₂ decomposition leading to increased ROS accumulation in infected host cells. Increased ROS in turn prevented nuclear translocation of NF-κB and inhibition of NF-κB target genes, leading to bacterial survival and enhanced replication inside host cells. Targeting Trxlp-mediated virulence promises to attenuate E. piscicida infection.

Obeticholic Acid Protects against Gestational Cholestasis-Induced Fetal Intrauterine Growth Restriction in Mice

Gestational cholestasis is a common disease and is associated with adverse pregnancy outcomes. However, there are still no effective treatments. We investigated the effects of obeticholic acid (OCA) on fetal intrauterine growth restriction (IUGR) during 17α-ethynylestradiol- (E2-) induced gestational cholestasis in mice. All pregnant mice except controls were subcutaneously injected with E2 (0.625 mg/kg) daily from gestational day (GD) 13 to GD17. Some pregnant mice were orally administered with OCA (5 mg/kg) daily from GD12 to GD17. As expected, OCA activated placental, maternal, and fetal hepatic FXR signaling. Additionally, exposure with E2 during late pregnancy induced cholestasis, whereas OCA alleviated E2-induced cholestasis. Gestational cholestasis caused reduction of fetal weight and crown-rump length and elevated the incidence of IUGR. OCA decreased the incidence of IUGR during cholestasis. Interestingly, OCA attenuated reduction of blood sinusoid area in placental labyrinth layer and inhibited downregulation of placental sodium-coupled neutral amino acid transporter- (SNAT-) 2 during cholestasis. Additional experiment found that OCA attenuated glutathione depletion and lipid peroxidation in placenta and fetal liver and placental protein nitration during cholestasis. Moreover, OCA inhibited the upregulation of placental NADPH oxidase-4 and antioxidant genes during cholestasis. OCA activated antioxidant Nrf2 signaling during cholestasis. Overall, we demonstrated that OCA treatment protected against gestational cholestasis-induced placental dysfunction and IUGR through suppressing placental oxidative stress and maintaining bile acid homeostasis.

Discovery of a Novel Periodontal Disease-Associated Bacterium

One of the world's most common infectious disease, periodontitis (PD), derives from largely uncharacterized communities of oral bacteria growing as biofilms (a.k.a. plaque) on teeth and gum surfaces in periodontal pockets. Bacteria associated with periodontal disease trigger inflammatory responses in immune cells, which in later stages of the disease cause loss of both soft and hard tissue structures supporting teeth. Thus far, only a handful of bacteria have been characterized as infectious agents of PD. Although deep sequencing technologies, such as whole community shotgun sequencing have the potential to capture a detailed picture of highly complex bacterial communities in any given environment, we still lack major reference genomes for the oral microbiome associated with PD and other diseases. In recent work, by using a combination of supervised machine learning and genome assembly, we identified a genome from a novel member of the Bacteroidetes phylum in periodontal samples. Here, by applying a comparative metagenomics read-classification approach, including 272 metagenomes from various human body sites, and our previously assembled draft genome of the uncultivated Candidatus Bacteroides periocalifornicus (CBP) bacterium, we show CBP's ubiquitous distribution in dental plaque, as well as its strong association with the well-known pathogenic "red complex" that resides in deep periodontal pockets.

Costimulatory Function of Cd58/Cd2 Interaction in Adaptive Humoral Immunity in a Zebrafish Model

CD58 and CD2 have long been known as a pair of reciprocal adhesion molecules involved in the immune modulations of CD8⁺ T and NK-mediated cellular immunity in humans and several other mammals. However, the functional roles of CD58 and CD2 in CD4⁺ T-mediated adaptive humoral immunity remain poorly defined. Moreover, the current functional observations of CD58 and CD2 were mainly acquired from in vitro assays, and in vivo investigation is greatly limited due to the absence of a Cd58 homology in murine models. In this study, we identified cd58 and cd2 homologs from the model species zebrafish (Danio rerio). These two molecules share conserved structural features to their mammalian counterparts. Functionally, cd58 and cd2 were significantly upregulated on antigen-presenting cells and Cd4⁺ T cells upon antigen stimulation. Blockade or knockdown of Cd58 and Cd2 dramatically impaired the activation of antigen-specific Cd4⁺ T and mIgM⁺ B cells, followed by the inhibition of antibody production and host defense against bacterial infections. These results indicate that CD58/CD2 interaction was required for the full activation of CD4⁺ T-mediated adaptive humoral immunity. The interaction of Cd58 with Cd2 was confirmed by co-immunoprecipitation and functional competitive assays by introducing a soluble Cd2 protein. This study highlights a new costimulatory mechanism underlying the regulatory network of adaptive immunity and makes zebrafish an attractive model organism for the investigation of CD58/CD2-mediated immunology and disorders. It also provides a cross-species understanding of the evolutionary history of costimulatory signals from fish to mammals as a whole.

Hyperoxidation of Peroxiredoxins: Gain or Loss of Function?

SIGNIFICANCE

In 2003, structural studies revealed that eukaryotic 2-Cys peroxiredoxins (Prx) have evolved to be sensitive to inactivation of their thioredoxin peroxidase activity by hyperoxidation (sulfinylation) of their peroxide-reacting catalytic cysteine. This was accompanied by the unexpected discovery, that the sulfinylation of this cysteine was reversible in vivo and the identification of a new enzyme, sulfiredoxin, that had apparently co-evolved specifically to reduce hyperoxidized 2-Cys Prx, restoring their peroxidase activity. Together, these findings have provided the impetus for multiple studies investigating the purpose of this reversible, Prx hyperoxidation. Recent Advances: It has been suggested that inhibition of the thioredoxin peroxidase activity by hyperoxidation can both promote and inhibit peroxide signal transduction, depending on the context. Prx hyperoxidation has also been proposed to protect cells against reactive oxygen species (ROS)-induced damage, by preserving reduced thioredoxin and/or by increasing non-peroxidase chaperone or signaling activities of Prx.

CRITICAL ISSUES

Here, we will review the evidence in support of each of these proposed functions, in view of the in vivo contexts in which Prx hyperoxidation occurs, and the role of sulfiredoxin. Thus, we will attempt to explain the basis for seemingly contradictory roles for Prx hyperoxidation in redox signaling.

FUTURE DIRECTIONS

We provide a rationale, based on modeling and experimental studies, for why Prx hyperoxidation should be considered a suitable, early biomarker for damaging levels of ROS. We discuss the implications that this has for the role of Prx in aging and the detection of hyperoxidized Prx as a conserved feature of circadian rhythms. Antioxid. Redox Signal. 28, 574-590.

Genomic footprints of dryland stress adaptation in Egyptian fat-tail sheep and their divergence from East African and western Asia cohorts

African indigenous sheep are classified as fat-tail, thin-tail and fat-rump hair sheep. The fat-tail are well adapted to dryland environments, but little is known on their genome profiles. We analyzed patterns of genomic variation by genotyping, with the Ovine SNP50K microarray, 394 individuals from five populations of fat-tail sheep from a desert environment in Egypt. Comparative inferences with other East African and western Asia fat-tail and European sheep, reveal at least two phylogeographically distinct genepools of fat-tail sheep in Africa that differ from the European genepool, suggesting separate evolutionary and breeding history. We identified 24 candidate selection sweep regions, spanning 172 potentially novel and known genes, which are enriched with genes underpinning dryland adaptation physiology. In particular, we found selection sweeps spanning genes and/or pathways associated with metabolism; response to stress, ultraviolet radiation, oxidative stress and DNA damage repair; activation of immune response; regulation of reproduction, organ function and development, body size and morphology, skin and hair pigmentation, and keratinization. Our findings provide insights on the complexity of genome architecture regarding dryland stress adaptation in the fat-tail sheep and showcase the indigenous stocks as appropriate genotypes for adaptation planning to sustain livestock production and human livelihoods, under future climates.