Molecular cloning and immunolocalization of the 17 kDa myoglobin of Clonorchis sinensis

In vivo and in vitro studies using Clonorchis sinensis adult-derived total protein (CsTP) on cellular function and inflammatory effect in mouse and cell model

Clonorchis sinensis (C. sinensis) can induce a food-borne parasitic disease (clonorchiasis). Numerous studies have analyzed functional proteins, immunologic factors, pro-inflammatory cytokines, and cell signaling transduction that promote the development of clonorchiasis. In a previous study, it was shown that C. sinensis adult-derived total protein (CsTP) might be involved in the pathogenesis and development of liver fibrosis via bringing about Th2 immune response. In the present study, further investigation of CsTP on cellular function and inflammatory effect in vitro and in vivo has been elicited. CsTP induced inflammation and autophagy as evidenced by upregulation of TNF-α, IFN-γ, and autophagic markers LC3B and P62. Exposed to CsTP upregulated the antiapoptotic gene Bcl-2 expression, diminished the apoptosis induced by H₂O₂, but promoted the proliferation and migration of LX-2 cells in proper concentration range. Additionally, the protein levels of p-AKT and p-mTOR were repressed in response to CsTP, suggesting a correlation of blocking the activation of mTOR/AKT signaling pathway. These results revealed that CsTP might exacerbate hepatic pathological changes by regulating cell proliferation, apoptosis, autophagy, and inflammation in the liver and LX-2 cells. Some effects might be partially involved in the mTOR and AKT pathways.

Expression of Clonorchis sinensis GIIIsPLA2 protein in baculovirus-infected insect cells and its overexpression facilitating epithelial-mesenchymal transition in Huh7 cells via AKT pathway

Although prior studies confirmed that group III secretory phospholipase A₂ of Clonorchis sinensis (CsGIIIsPLA₂) had stimulating effect on liver fibrosis by binding to LX-2 cells, large-scale expression of recombinant protein and its function in the progression of hepatoma are worth exploring. Because of high productivity and low lipopolysaccharides (LPS) in the Sf9-baculovirus expression system, we firstly used this system to express the coding region of CsGIIIsPLA₂. The molecular weight of recombinant CsGIIIsPLA₂ protein was about 34 kDa. Further investigation showed that most of the recombinant protein presented intracellular expression in Sf9 insect cell nucleus and could be detected only into cell debris, which made the protein purification and further functional study difficult. Therefore, to study the role of CsGIIIsPLA₂ in hepatocellular carcinoma (HCC) progression, CsGIIIsPLA₂ overexpression Huh7 cell model was applied. Cell proliferation, migration, and the expression level of epithelial-mesenchymal transition (EMT)-related molecules (E-cadherin, N-cadherin, α-catenin, Vimentin, p300, Snail, and Slug) along with possible mechanism were measured. The results indicated that CsGIIIsPLA₂ overexpression not only inhibited cell proliferation and promoted migration and EMT but also enhanced the phosphorylation of AKT in HCC cells. In conclusion, this study supported that CsGIIIsPLA₂ overexpression suppressed cell proliferation and induced EMT through the AKT pathway.

Molecular characterization of severin from Clonorchis sinensis excretory/secretory products and its potential anti-apoptotic role in hepatocarcinoma PLC cells

BACKGROUND

Clonorchiasis, caused by the infection of Clonorchis sinensis (C. sinensis), is a kind of neglected tropical disease, but it is highly related to cholangiocarcinoma and hepatocellular carcinoma (HCC). It has been well known that the excretory/secretory products of C. sinensis (CsESPs) play key roles in clonorchiasis associated carcinoma. From genome and transcriptome of C. sinensis, we identified one component of CsESPs, severin (Csseverin), which had three putative gelsolin domains. Its homologues are supposed to play a vital role in apoptosis resistance of tumour cell.

METHODOLOGY/PRINCIPAL FINDINGS

There was significant similarity in tertiary structures between human gelsolin and Csseverin by bioinformatics analysis. We identified that Csseverin expressed at life stage of adult worm, metacercaria and egg by the method of quantitative real-time PCR and western blotting. Csseverin distributed in vitellarium and intrauterine eggs of adult worm and tegument of metacercaria by immunofluorence assay. We obtained recombinant Csseverin (rCsseverin) and confirmed that rCsseverin could bind with calciumion in circular dichroism spectrum analysis. It was demonstrated that rCsseverin was of the capability of actin binding by gel overlay assay and immunocytochemistry. Both Annexin V/PI assay and mitochondrial membrane potential assay of human hepatocarcinoma cell line PLC showed apoptosis resistance after incubation with different concentrations of rCsseverin. Morphological analysis, apoptosis-associated changes of mitochondrial membrane potential and Annexin V/PI apoptosis assay showed that co-incubation of PLC cells with rCsseverin in vitro led to an inhibition of apoptosis induced by serum-starved for 24 h.

CONCLUSIONS/SIGNIFICANCE

Collectively, the molecular properties of Csseverin, a molecule of CsESPs, were characterized in our study. rCsseverin could cause obvious apoptotic inhibition in human HCC cell line. Csseverin might exacerbate the process of HCC patients combined with C. sinensis infection.

Adult Opisthorchis felineus major protein fractions deduced from transcripts: comparison with liver flukes Opisthorchis viverrini and Clonorchis sinensis

The epidemiologically important liver flukes Opisthorchis felineus, Opisthorchis viverrini, and Clonorchis sinensis are of interest to health professionals, epidemiologists, pharmacologists, and molecular biologists. Recently the transcriptomes of the latter two species were intensively investigated. However our knowledge on molecular biology of O. felineus is scarce. We report the first results of the O. felineus transcriptome analysis. We isolated and annotated a total of 2560 expressed sequence tag (EST) sequences from adult O. felineus (deposited within the database of expressed sequence tags (dbEST), under accession numbers GenBank: JK624271-JK626790, JK006511-JK006547, JK649790-JK649792). Clustering and analysis resulted in the detection of 267 contigs. Of the protein sequences deduced from these, 82% had homologs in the NCBI (nr) protein database and 63% contained conserved domains, allowing the functions to be interpreted using the Gene Ontology terms. Comprehensive analysis of Opisthorchiidae- and Trematoda-specific substitutions within amino acid sequences deduced for the proteins myoglobin, vitelline precursor protein, cathepsin F, and 28kDa glutathione transferase was carried out. The gene set of the 32 ribosomal proteins for the three Opisthorchiidae species with the addition of available Schistosoma and Fasciola orthologs was created and is provided in the supplementary. The orthologous gene set created was used for inferring phylogeny within the Trematoda with special attention to interrelations within the Opisthorchiidae. The phylogenetic analysis revealed a closer relationship between C. sinensis and O. viverrini and some divergence of O. felineus from either O. viverrini or C. sinensis.

Identification and characterization of myophilin-like protein: a life stage and tissue-specific antigen of Clonorchis sinensis

Clonorchiasis, caused by Clonorchis sinensis infection, has been an important public health problem in China. More messages about biology and pathogenicity of C. sinensis will be better for development of new strategies for clonorchiasis control. In the current study, using data from the published genomic and cDNA sequences for C. sinensis, we identify a gene encoding a myophilin-like protein (Cs myophilin-like). The cDNA sequence is 573 bp in length which encoded a protein of 190 amino acids. DNA sequence of Cs myophilin-like consists of four extrons and three introns. By mapping the draft genome of C. sinensis, single copy of myophilin-like gene is annotated. Bioinformatic analysis shows Cs myophilin-like comprises a calponin homology domain and three actin binding surfaces. It expresses at the life stage of adult worm and metacercaria but not in eggs. It intensively distributes in muscular locations such as oral sucker and pharynx of adult worm and sucker of metacercaria. The transcript level of Cs myophilin-like in oral sucker and pharynx is significantly higher than that in the rest of adult worm. Moreover, recombinant Cs myophilin-like is obtained and of antigenicity and immunoreactivity. It can be probed by sera from patients infected with trematode or cestode. Our data suggests that Cs myophilin-like may be involved in the host tissue invasion besides regulating the contraction of smooth muscle and movement of worm body. Taken together, the stable and soluble expression in Escherichia coli and immunogenicity of recombinant Cs myophilin-like proteins suggest that Cs myophilin-like may be a potential candidate for vaccine and drug target for clonorchiasis.

Functional genes and proteins of Clonorchis sinensis

During the past several decades, researches on parasite genetics have progressed from biochemical and serodiagnostic studies to protein chemistry, molecular biology, and functional gene studies. Nowadays, bioinformatics, genomics, and proteomics approaches are being applied by Korean parasitology researchers. As for Clonorchis sinensis, investigations have been carried out to identify its functional genes using forward and reverse genetic approaches and to characterize the biochemical and biological properties of its gene products. The authors review the proteins of cloned genes, which include antigenic proteins, physiologic and metabolic enzymes, and the gene expression profile of Clonorchis sinensis.

Molecular characterization of two myoglobins of Paragonimus westermani

Myoglobins (Mbs), globin proteins, are present in high concentrations in trematodes. In Paragonimus westermani, 2 cDNAs were found to encode Mbs. The first clone, Pwmyo1, codes a total of 149 amino acids with a calculated mass of 16.6 kDa. The second, Pwmyo2, encodes a 146-amino acid protein with a calculated mass of 16.2 kDa. The predicted secondary structures showed the presence of 8 helices, which is the basic characteristic of Mbs. Sequence alignment revealed a high homology with the other trematode Mbs. The 2 clones contained the characteristic tyrosyl residues at helical positions B10 and distal E7, which are substitutions that have been previously shown to contribute to the high oxygen affinity of Mbs. Polyclonal antibodies against the recombinant Mbs were raised with no cross-reactivity observed. Immunolocalization revealed the proteins to be distributed generally throughout the parenchymal tissues, but absent from the tegument and reproductive organs. The cell mass of the eggs of the worm stained positive to Pwmyo2 but not Pwmyo1, suggesting the stage-specific expression of these Mbs.

COMPARISON OF GENE REPRESENTATION BETWEEN DIPLOID AND TRIPLOID PARAGONIMUS WESTERMANI BY EXPRESSED SEQUENCE TAG ANALYSES

Expressed sequence tag (EST) analysis of the diploid and triploid Paragonimus westermani genes was done to have a rapid and informative outlook of the gene-expression profiles of the parasites. Totals of 506 and 505 ESTs were generated from the diploid and triploid P. westermani cDNA libraries. Based on the BLASTx search results of the diploid P. westermani ESTs, 308 (60.9%) matched significantly with formerly identified genes and 198 (39.1%) showed no significant homology in the GenBank database. A similar homology pattern was shown from the triploid EST BLASTx search results with 346 (68.5%) sharing homology with previously identified genes and 159 (31.5%) showing no significant homology. The EST data from both libraries were analyzed and grouped into 9 categories. Comparison of the 2 EST pools revealed high similarities among the categories of the significantly matched genes. Single genes matched repeatedly were also observed in the 2 EST data. Some genes were found that are not yet characterized in P. westermani; these genes were matched by both the diploid and triploid ESTs. Further study of these genes may provide us with more understanding on the parasite's biology and their specific functions in the 2 strains.

Clonorchiasis: an update

Clonorchis sinensis, the Chinese or oriental liver fluke, is an important human parasite and is widely distributed in southern Korea, China (including Taiwan), Japan, northern Vietnam and the far eastern part of Russia. Clonorchiasis occurs in all parts of the world where there are Asian immigrants from endemic areas. The human and animal reservoir hosts (dogs, pigs, cats and rats) acquire the infection from the ingestion of raw fish containing infectious metacercariae. The first intermediate snail hosts are mainly species of Parafossarulus and Bithynia. Numerous species of freshwater fish serve as the second intermediate hosts of C. sinensis. Extensive studies of clonorchiasis during several decades in Japan, Korea, China and other countries have shown much progress in proving its morphological features including ultrastructure, biology, pathogenesis, epidemiology, clinical manifestations and chemotherapy. The present review deals with mainly current results obtained on the epidemiological, pathological and clinical aspects, as well as control measures in endemic areas. As for the complications of clonorchiasis, formation of calculi in the intrahepatic biliary passages is one of the most characteristic pathological features. It is sometimes accompanied by suppurative cholangitis, cholecystitis, cholangiohepatitis and ultimately can cause cholangiocarcinoma. Experimental results on the relationship to the occurrence of cholangiocarcinoma are presented. Clinical diagnosis by radiological findings including cholangiography, sonography and computerized tomography as well as magnetic resonance imaging for biliary or pancreatic ducts are outlined. Current studies on immunology and molecular biology of C. sinensis were introduced. Praziquantel is the drug of choice for clonorchiasis. The most effective regimen is 25 mg kg(-1) three times daily (total dose, 75 mg kg(-1)) administered orally at 5- to 6-h intervals over a single day. Prevention and control measures are also discussed.

Organ-specific antigens of Clonorchis sinensis

This study was carried out to find out specific proteins from different organs of Clonorchis sinensis. Crude extract, organ-specific and excretory-secretory (ES) proteins were analyzed by immunoblot with infected human sera. The bands of 7- and 17-kDa were main component of intestinal fluid and ES protein and commonly found in all organspecific proteins. The 17-kDa protein was observed from ES antigen, intestinal fluid, eggs and sperms, 26- and 28-kDa proteins were from the uterus, vitellaria, and ovary, and 34-, 37-, 43- and 50-kDa proteins were mainly from the testis and sperms. Serum of mice immunized with sperms reacted to the 50-kDa protein by immunoblotting and immunohistochemical staining showed a positive reaction at the seminal receptacle and seminiferous tubule. The present results show that the 7-kDa protein is a common antigen of every part or organ of C. sinensis, but different organs express their specific antigenic protein bands.