Characterization of the antioxidant enzyme, thioredoxin peroxidase, from the carcinogenic human liver fluke, Opisthorchis viverrini

Abstract

The human liver fluke, Opisthorchis viverrini, induces inflammation of the hepatobiliary system. Despite being constantly exposed to inimical oxygen radicals released from inflammatory cells, the parasite survives for many years. The mechanisms by which it avoids oxidative damage are unknown. In this study, thioredoxin peroxidase (TPx), a member of the peroxiredoxin superfamily, was cloned from an O. viverrini cDNA library. O. viverrini TPx cDNA encoded a polypeptide of 212 amino acid residues, of molecular mass 23.57 kDa. The putative amino acid sequence shared 60-70% identity with TPXs from other helminths and from mammals, and phylogenetic analysis revealed a close relationship between TPxs from O. viverrini and other trematodes. Recombinant O. viverrini TPx was expressed as soluble protein in Escherichia coli.The recombinant protein dimerized, and its antioxidant activity was deduced by observing protection of nicking of supercoiled plasmid DNA by hydroxyl radicals. Antiserum raised against O. viverrini TPx recognized native proteins from egg, metacercaria and adult developmental stages of the liver fluke and excretory-secretory products released by adult O. viverrini. Immunolocalization studies revealed ubiquitous expression of TPx in O. viverrini organs and tissues. TPx was also detected in bile fluid and bile duct epithelial cells surrounding the flukes two weeks after infection of hamsters with O. viverrini. In addition, TPx was observed in the secondary (small) bile ducts where flukes cannot reach due to their large size. These results suggested that O. viverrini TPx plays a significant role in protecting the parasite against damage induced by reactive oxygen species from inflammation.

Identification, genomic organization, and oxidative stress response of a sigma class glutathione S-transferase gene (AccGSTS1) in the honey bee, Apis cerana cerana

“…As sigma class proteins have been shown to be involved in lipid peroxidation in Drosophila (Agianian et al 2003), we next determined the antioxidant properties of AccGSTS1 by measuring the removal of H 2 O 2 in a reaction mixture with DTT as an electron donor (Suttiprapa et al 2008). As shown in Fig.…”

A comparative proteomic analysis of bile for biomarkers of cholangiocarcinoma

“…Western blot analysis was performed as previously described. 17 Briefly, 5 µL of bile sample was separated by 15% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with 20 mA for 2 h. Separated proteins were then transferred to nitrocellulose membrane. Non-specific binding was blocked by incubating membrane in 5% skimmed milk in PBS with 0.05% Tween 20 (PBST) at 25°C for 1 h. The membrane was then incubated for 1 h with 1:1000 diluted rabbit anti-alpha 1 antitrypsin antibody (polyclonal, ab9373; Abcam) in 2% skimmed milk in PBST at 25°C.…”

Functional Genes and Proteins of Clonorchis sinensis

“…C. sinensis-infection provokes inflammation, hyperplasia of the biliary epithelium and periductal fibrosis of intrahepatic bile ducts [2]. Furthermore, C. sinensis infection can initiate the development of cholangiocarcinoma in biliary epithelial cells in the presence of chronic inflammation and hyperplastic proliferation [3,4]. In fact, it has been shown epidemiologically that clonorchiasis increases the prevalence of cholangiocarcinoma in endemic areas [5].…”

“…It is obvious that the ES products of C. sinensis contain components that provoke pathologic changes in biliary epithelium, and molecules produced by C. sinensis have been shown to stimulate inflammation and the productions of endogenous bioreactive radicals in epithelial cells, and these radicals not only cause DNA damage but inhibit the repair of DNA damage, and thus, promote mutation [3,5]. The molecules responsible and the pathologic progress occurring in and around the biliary tract have long been of research interest.…”