Identification and characterization of peroxiredoxin 1 from Lateolabrax japonicus under biotic and abiotic stresses

Molecular characterization, cytoprotective, DNA protective, and immunological assessment of peroxiredoxin-1 (Prdx1) from yellowtail clownfish (Amphiprion clarkii)

Peroxiredoxin-1 (Prdx1) is a thiol-specific antioxidant enzyme that detoxifies reactive oxygen species (ROS) and regulates the redox status of cells. In this study, the Prdx1 cDNA sequence was isolated from the pre-established Amphiprion clarkii (A. clarkii) (AcPrdx1) transcriptome database and characterized structurally and functionally. The AcPrdx1 coding sequence comprises 597 bp and encodes 198 amino acids with a molecular weight of 22.1 kDa and a predicted theoretical isoelectric point of 6.3. AcPrdx1 is localized and functionally available in the cytoplasm and nucleus of cells. The TXN domain of AcPrdx1 comprises two peroxiredoxin signature VCP motifs, which contain catalytic peroxidatic (Cp-C52) and resolving cysteine (CR-C173) residues. The constructed phylogenetic tree and sequence alignment revealed that AcPrdx1 is evolutionarily conserved, and its most closely related counterpart is Amphiprion ocellaris. Under normal physiological conditions, AcPrdx1 was ubiquitously detected in all tissues examined, with the most robust expression in the spleen. Furthermore, AcPrdx1 transcripts were significantly upregulated in the spleen, head kidney, and blood after immune stimulation by polyinosinic:polycytidylic acid (poly (I:C)), lipopolysaccharide (LPS), and Vibrio harveyi injection. Recombinant AcPrdx1 (rAcPrdx1) demonstrated antioxidant and DNA protective properties in a concentration-dependent manner, as evidenced by insulin disulfide reduction, peroxidase activity, and metal-catalyzed oxidation (MCO) assays, whereas cells transfected with pcDNA3.1(+)/AcPrdx1 showed significant cytoprotective function under oxidative and nitrosative stress. Overexpression of AcPrdx1 in fathead minnow (FHM) cells led to a lower viral copy number following viral hemorrhagic septicemia virus (VHSV) infection, along with upregulation of several antiviral genes. Collectively, this study provides insights into the function of AcPrdx1 in defense against oxidative stressors and its role in the immune response against pathogenic infections in A. clarkii.

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.

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.

Peroxiredoxin 1 of Procambarus clarkii govern immune responses during pathogen infection

Members of the peroxiredoxin family are involved in a wide variety of physiological processes, including the ability to combat the effects of oxidative stress and immune responses, among others. Here, we cloned the cDNA of Procambarus clarkii Peroxiredoxin 1 (designated as PcPrx-1) and investigated its biological role in immune system functions in relation to microbial pathogens. The PcPrx-1 cDNA had 744 base pairs in an open reading frame that encoded 247 amino acid residues and contained a PRX_Typ2cys domain. The analysis of tissue specific expression patterns revealed that PcPrx-1 expression was ubiquitous in all tissues. In addition, the mRNA transcript of PcPrx-1 was found to be highest in the hepatopancreas. There was a significant upregulation of PcPrx-1 gene transcripts after exposure to LPS, PGN, and Poly I:C, but the transcription patterns were different after pathogen challenge. Double-stranded RNA was used to knockdown PcPrx-1, which resulted in a striking change in the expression of all the tested P. clarkii immune-associated genes, including lectin, Toll, cactus, chitinase, phospholipase, and sptzale. On the whole, these results suggest that PcPrx-1 is important to confer innate immunity against pathogens by governing the expression of critical transcripts that encode immune-associated genes.

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.

Vitamin C regulates the production of reactive oxygen species through Wnt10b signaling in the gill of zebrafish

In this study, the mechanism that vitamin C (VC) regulates the production of reactive oxygen species (ROS) through Wnt10b signaling was investigated in the gill of zebrafish (Danio rerio). The results showed that 0.5 and 1.0 g/kg VC diets induced the gene expression of Wnt10b, β-catenin, SOD, CAT, and GSH-PX in gill. In addition, VC decreased the levels of H₂O₂, O₂^·- and ·OH, whereas the activities of SOD, CAT, and GSH-PX were increased by VC in the gill of zebrafish. To evaluate the role of Wnt10b in regulating oxidative stress, Wnt10b RNA was further interfered and the gene expression and activities of antioxidant enzymes were detected in gill. The result of Wnt10b RNA interference showed that Wnt10b signaling played a key role in regulating the gene expression of SOD, CAT, and GSH-PX. In all, VC may regulate the production of ROS through Wnt10b signaling in the gill of zebrafish (Danio rerio).

Identification of co-chaperone Cdc37 in Penaeus monodon: coordination with Hsp90 can reduce cadmium stress-induced lipid peroxidation

Cell division cycle 37 (Cdc37) is an important cytoplasmic phosphoprotein, which usually functions as a complex with heat shock protein 90 (Hsp90), to effectively reduce the damage caused by heavy metals, such as cadmium (Cd), in aquatic animals. The high toxicity of Cd in aquatic systems generally has a deleterious effect on healthy farming of shrimps. In the present study, a novel Cdc37 gene from Penaeus monodon was identified and designated as PmCdc37. Following exposure to Cd stress, the expression levels of PmCdc37 were upregulated at the transcriptional level in both the hepatopancreas and hemolymph. RNA interference and recombinant protein injection experiments were carried out to determine the function of PmCdc37 in P. monodon following Cd exposure. To clarify the correlations between PmCdc37 and PmHsp90, the respective recombinant proteins were expressed in vitro, and the ATPase activity of PmHsp90, with or without PmCdc37, was assessed. Moreover, a pull-down assay was conducted to detect the correlation between PmCdc37 and PmHsp90. After analyzing the expression patterns of PmHsp90 following Cd challenge, whether PmHsp90 can promote the ability of PmCdc37 to resist Cd stress or not was investigated. The results showed that formation of a PmHsp90/PmCdc37 complex protected shrimp against Cd stress-induced damage. Moreover, we also confirmed that PmSOD is involved in Cd stress, and that the PmHsp90/PmCdc37 complex can regulate SOD enzymatic activity. PmSOD was involved in decreasing the MDA content in shrimp hemolymph caused by Cd stress. We concluded that during exposure to Cd, the PmHsp90/PmCdc37 complex increases SOD enzyme activity, and in turn decreases the MDA content, thereby protecting shrimp against the damage caused by Cd stress. The present studies contribute to understanding the molecular mechanism underlying resistance to Cd stress in shrimp.

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.

Characterization of a classical 2-cysteine peroxiredoxin1 gene from Chinese soft-shelled turtle Pelodiscus sinensis with its potent antioxidant properties and putative immune response

Peroxiredoxin family members could function in host defense against oxidative stress, and modulate immune response. In the present study, a 2-cysteine peroxiredoxin gene named PsPrx1 was isolated from Chinese soft-shelled turtle Pelodiscus sinensis. The PsPrx1 cDNA was composed of 1130 bp, consisted of 199 amino acid residues and included a Redoxin and AphC-TSA domain. As detected by qPCR, PsPrx1 was ubiquitously expressed in the examined tissues with the higher levels in liver and spleen. Upon the immune challenge with A. jandaei bacteria and oxidative stress with ammonia pressure, both mRNA and protein expression level in liver could be significantly enhanced. The results of immunohistochemical examinations showed PsPrx1 was mainly distributed at the junction between the hepatic cells. The general functional properties of PsPrx1 were confirmed using purified rPsPrx1 protein. From the results, rPsPrx1 protein was confirmed to exhibit antioxidant activity and antibacterial properties. The potential for scavenging extracellular H₂O₂ was evidenced by the purified rPsPrx1 protein in vitro system. In the mixed-function oxidase assay, rPsPrx1 also exhibited a dose-dependent inhibition of DNA damage. These results suggest that rPsPrx1 was implicated defense against microbial pathogens and oxidants, and would provide important information to further understand the functional mechanism of Prx1 in P. sinensis immunity.

Molecular characterization and functional activity of Prx1 in grass carp (Ctenopharyngodon idella)

Peroxiredoxin (Prx) family are known as an important antioxidant enzyme as the first line of defense against oxidative damage, and also involved in immune responses following viral and bacterial infection. Here, a full-length Prx1 cDNA sequence (CiPrx1) was cloned from grass carp (Ctenopharyngodon idella), which was 1029 bp, including a 5'-terminal untranslated region (UTR) of 121 bp, a 3'-UTR of 272 bp, an open reading frame of 600 bp encoding 199 amino acids with molecular weight of 22.21 kDa and isoelectric point of 6.30. CiPrx1 shares 80.8-99% protein sequence similarity with Prx1 of other fishes. The conserved peroxidase catalytic center "FYPLDFTFVCPTEI" and "GEVCPA" were observed in the sequence of CiPrx1; this indicated that it was a member of 2-Cys Prx. Subcellular localization of CiPrx1 was only strongly distributed in the cytoplasm. Quantitative real-time PCR (RT-qPCR) assays revealed that CiPrx1 mRNA was ubiquitously detected in all tested tissues, and the expression was comparatively high in liver, gill and spleen. Further, the expression of CiPrx1 can be induced by grass carp reovirus (GCRV), lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (Poly I:C) infection in the different tissues. Moreover, the recombinant CiPrx1 (rCiPrx1) protein was found a potential antioxidant enzyme, that could inhibit DNA damage from oxidants. Altogether, our results imply that CiPrx1 is associated with defending against virus and bacteria pathogens and oxidants in grass carp.