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Clonorchis sinensis omega-class glutathione transferases play major roles in the protection of the reproductive system during maturation and the response to oxidative stress.

ABSTRACT: BACKGROUND:Clonorchis sinensis causes a major food-borne helminthic infection. This species locates in mammalian hepatobiliary ducts, where oxidative stressors and hydrophobic substances are profuse. To adapt to the hostile micromilieu and to ensure its long-term survival, the parasite continuously produces a diverse repertoire of antioxidant enzymes including several species of glutathione transferases (GSTs). Helminth GSTs play pertinent roles during sequestration of harmful xenobiotics since most helminths lack the cytochrome P-450 detoxifying enzyme. METHODS:We isolated and analyzed the biochemical properties of two omega-class GSTs of C. sinensis (CsGSTo1 and CsGSTo2). We observed spatiotemporal expression patterns in accordance with the maturation of the worm's reproductive system. Possible biological protective roles of CsGSTos in these organs under oxidative stress were investigated. RESULTS:The full-length cDNAs of CsGSTo1 and 2 constituted 965 bp and 1,061 bp with open reading frames of 737 bp (246 amino acids) and 669 bp (223 amino acids). They harbored characteristic N-terminal thioredoxin-like and C-terminal ?-helical domains. A cysteine residue, which constituted omega-class specific active site, and the glutathione-binding amino acids, were recognized in appropriate positions. They shared 44 % sequence identity with each other and 14.8-44.8 % with orthologues/homologues from other organisms. Bacterially expressed recombinant proteins (rCsGSTo1 and 2) exhibited dehydroascorbate reductase (DHAR) and thioltransferase activities. DHAR activity was higher than thioltransferase activity. They showed weak canonical GST activity toward 1-chloro-2,4-dinitrobenzene. S-hexylglutathione potently and competitively inhibited the active-site at nanomolar concentrations (0.63 and 0.58 nM for rCsGSTo1 and 2). Interestingly, rCsGSTos exhibited high enzyme activity toward mu- and theta-class GST specific substrate, 4-nitrobenzyl chloride. Expression of CsGSTo transcripts and proteins increased beginning in 2-week-old juveniles and reached their highest levels in 4-week-old adults. The proteins were mainly expressed in the elements of the reproductive system, such as vitelline follicles, testes, seminal receptacle, sperm and eggs. Oxidative stressors induced upregulated expression of CsGSTos in these organs. Regardless of oxidative stresses, CsGSTos continued to be highly expressed in eggs. CsGSTo1 or 2 overexpressing bacteria demonstrated high resistance under oxidative killing. CONCLUSIONS:CsGSTos might be critically involved in protection of the reproductive system during maturation of C. sinensis worms and in response to oxidative conditions, thereby contributing to maintenance of parasite fecundity.

SUBMITTER: Kim JG

PROVIDER: S-EPMC4906895 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Clonorchis sinensis omega-class glutathione transferases play major roles in the protection of the reproductive system during maturation and the response to oxidative stress.

Kim Jeong-Geun JG Ahn Chun-Seob CS Kim Seon-Hee SH Bae Young-An YA Kwon Na-Young NY Kang Insug I Yang Hyun-Jong HJ Sohn Woon-Mok WM Kong Yoon Y

Parasites & vectors 20160613 1

<h4>Background</h4>Clonorchis sinensis causes a major food-borne helminthic infection. This species locates in mammalian hepatobiliary ducts, where oxidative stressors and hydrophobic substances are profuse. To adapt to the hostile micromilieu and to ensure its long-term survival, the parasite continuously produces a diverse repertoire of antioxidant enzymes including several species of glutathione transferases (GSTs). Helminth GSTs play pertinent roles during sequestration of harmful xenobiotic ...[more]

PMID: 27296469

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Project description:The small liver fluke Clonorchis sinensis causes hepatobiliary ductal infections in humans. Clonorchiasis is characterized histopathologically by ductal dysplasia, hyperplasia and metaplasia, which closely resembles cholangiocarcinoma (CCA). The disruption of programmed cell death is critical for malignant transformation, while molecular events underlying these phenomena have poorly been understood in clonorchiasis-related CCA tumorigenesis. We incorporated recombinant C. sinensis omega-class glutathione transferase (rCsGSTo) 1 or 2 into human intrahepatic biliary epithelial cells (HIBECs) and analyzed pathophysiological alterations of HIBECs upon the application of oxidative stress. rCsGSTos partially but significantly rescued HIBECs from cell death by inhibiting oxidative stress-induced apoptosis (p < 0.01). rCsGSTos modulated transcriptional levels of numerous genes. We analyzed 13 genes involved in programmed cell death (the upregulation of five antiapoptotic and two apoptotic genes, and the downregulation of one antiapoptotic and five apoptotic genes) and 11 genes associated with cell differentiation (the increase in seven and decrease in four genes) that showed significant modifications (p < 0.05). The induction profiles of the mRNA and proteins of these differentially regulated genes correlated well with each other, and mostly favored apoptotic suppression and/or cell differentiation. We detected increased active, phosphorylated forms of Src, PI3K/Akt, NF-κB p65, MKK3/6 and p38 MAPK, but not JNK and ERK1/2. CsGSTos were localized in the C. sinensis-infected rat cholangiocytes, where cytokeratin 19 was distributed. Our results demonstrated that CsGSTos excreted to the biliary lumen are internalized and accumulated in the host cholangiocytes. When cholangiocytes underwent oxidative stressful condition, CsGSTos appeared to be critically involved in both antiapoptotic process and the differentiation of host cholangiocytes through the regulation of target genes following the activation of responsible signal molecules.

Project description:Pathogenic helminths have evolved mechanisms to preserve reproductive function while surviving long-term in the host via robust protective responses. A protective role of antioxidant enzymes in preventing DNA degradation has long been proposed, but little evidence has been provided. Here, we show that omega-class glutathione transferases (GSTOs) are critical for maintaining viability by protecting the reproductive cell DNA of the carcinogenic liver fluke, Clonorchis sinensis. Clonorchis sinensis GSTO (CsGSTO) activities modified by changes in the GSH/GSSG and NADPH/NADP+ molar ratios suppressed the overproduction of reactive oxygen species. CsGSTO1 and CsGSTO2 catalyzed deglutathionylation under physiologic and low-stress conditions (GSH/GSSG ratio of 6:1 or higher) but promoted glutathionylation under high-stress conditions (GSH/GSSG ratio of 3:1 or lower). Gliotoxin-induced functional disruption of CsGSTOs in living C. sinensis reduced the GSH/GSSG molar ratio and increased the production of protein glutathionylation (PSSG) under physiologic and low-stress conditions, indicating that suppression of GSTO function did not affect deglutathionylation. However, the perturbation of CsGSTOs decreased the GSH/GSSG ratio but also reduced PSSG production under high oxidative stress, demonstrating that glutathionylation was impeded. In response to oxidative stimuli, C. sinensis decreased GSTO-specific dehydroascorbate reductase and thiol transferase activities and the GSH/GSSG ratio, while it increased the NADPH/NADP+ ratio and PSSG. CsGSTOs utilized GSH to regulate GSH/GSSG and NADPH/NADP+ recycling and triggered a redox signal leading to nuclear translocation. Nuclear-imported CsGSTOs were modified by glutathionylation to prevent DNA damage. Antibodies specific to CsGSTOs dose-dependently inhibited this process. Disruption of CsGSTOs or the depletion of GSH caused glutathionylation defects, leading to DNA degradation. Our results demonstrate that CsGSTOs and the GSH system play a previously unappreciated role in protecting DNA from oxidative stress.

Project description:BackgroundClonorchis sinensis causes chronic cumulative infections in the human hepatobiliary tract and is intimately associated with cholangiocarcinoma. Approximately 35 million people are infected and 600 million people are at risk of infections worldwide. C. sinensis excretory-secretory products (ESP) constitute the first-line effector system affecting the host-parasite interrelationship by interacting with bile fluids and ductal epithelium. However, the secretory behavior of C. sinensis in an environment close to natural host conditions is unclear. C. sinensis differs from Fasciola hepatica in migration to, and maturation in, the hepatic bile duct, implying that protein profile of the ESP of these two trematodes might be different from each other.Methodology/principal findingsWe conducted systemic approaches to analyze the C. sinensis ESP proteome and the biological reactivity of C. sinensis glutathione transferases (GSTs), such as global expression patterns and induction profiles under oxidative stress and host bile. When we observed ex host excretion behavior of C. sinensis in the presence of 10% host bile, the global proteome pattern was not significantly altered, but the amount of secretory proteins was increased by approximately 3.5-fold. Bioactive molecules secreted by C. sinensis revealed universal/unique features in relation to its intraluminal hydrophobic residing niche. A total of 38 protein spots identified abundantly included enzymes involved in glucose metabolism (11 spots, 28.9%) and diverse-classes of glutathione transferases (GSTs; 10 spots, 26.3%). Cathepsin L/F (four spots, 10.5%) and transporter molecules (three spots, 7.9%) were also recognized. The universal secretory proteins found in other parasites, such as several enzymes involved in glucose metabolism and oxygen transporters, were commonly detected. C. sinensis secreted less cysteine proteases and fatty acid binding proteins compared to other tissue-invading or intravascular trematodes. Interestingly, secretion of a 28 kDa ?-class GST (Cs28?GST3) was significantly affected by the host bile, involving reduced secretion of the 28 kDa species and augmented secretion of Cs28?GST3-related high-molecular-weight 85 kDa protein. Oxidative stressors induced upregulated secretion of 28 kDa Cs28?GST3, but not an 85 kDa species. A secretory 26 kDa ?-class GST (Cs26?GST2) was increased upon treatment with oxidative stressors and bile juice, while another 28 kDa ?-class GST (Cs28?GST1) showed negligible responses.Conclusions/significanceOur results represent the first analysis of the genuine nature of the C. sinensis ESP proteome in the presence of host bile mimicking the natural host environments. The behavioral patterns of migration and maturation of C. sinensis in the bile ducts might contribute to the secretion of copious amounts of diverse GSTs, but a smaller quantity and fewer kinds of cysteine proteases. The Cs28?GST1 and its paralog(s) detoxify endogenous oxidative molecules, while Cs28?GST3 and Cs26?GST2 conjugate xenobiotics/hydrophobic substances in the extracellular environments, which imply that diverse C. sinensis GSTs might have evolved for each of the multiple specialized functions.

Project description:BackgroundClonorchiasis is endemic in East and Southeast Asian countries. For a preventive strategy against infectious diseases, vaccination is the most effective. Here, we evaluated the molecular characteristics and immune responses of CsAg17 protein from Clonorchis sinensis, and investigated its protective effects against C. sinensis challenge.MethodsA cDNA clone encoding CsAg17 protein and containing a secretory signal peptide at the N-terminus was retrieved from the C. sinensis transcriptome bank. Recombinant CsAg17 B-cell epitope protein and cDNA vaccines were produced and their immune responses were evaluated in FVB mice. The proportional changes of CD3+/CD4+ and CD3+/CD8+ T cells were detected by flow cytometry, and immune effectors were measured by ELISA.ResultsThe CsAg17 mRNA was transcribed at a higher level in C. sinensis adults than in metacercariae. The CsAg17 protein was distributed in the sperms, oral and ventral suckers, and mesenchymal tissues of C. sinensis adults. In mice challenged with C. sinensis metacercariae, vaccination with CsAg17 protein and cDNA resulted in a reduction to 64% and 69% in worm burden, respectively. Both CsAg17 protein and cDNA vaccines increased the proportion of CD3+/CD4+ and CD3+/CD8+ T cells and stimulated the production of Th1 type cytokines such as interleukin (IL)-2, IL-12, and interferon-γ, while maintaining minimum levels of Th2 cytokines. The levels of IgG specific to CsAg17 protein steeply increased in the two vaccinated groups from 2 weeks after immunization. The liver tissue retained good morphology in the mice vaccinated with CsAg17 protein or cDNA, whereas severe inflammation and large serous cysts were observed in the liver of the unvaccinated mice.ConclusionsVaccination with CsAg17 protein and cDNA reduced the pathological changes in the bile duct and liver, and ameliorated the worm burden via cellular and humoral immune responses. Thus, they may serve as good vaccine candidates against C. sinensis infections.

Dataset Information

Clonorchis sinensis omega-class glutathione transferases play major roles in the protection of the reproductive system during maturation and the response to oxidative stress.

Publications

Clonorchis sinensis omega-class glutathione transferases play major roles in the protection of the reproductive system during maturation and the response to oxidative stress.

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