A study on the synthesi and absorption of cholesterol in hydatid cysts (Echinococcus granulosus)

Frayha, George J.

doi:10.1016/0010-406x(68)90629-4

Cited by 30 publications

(9 citation statements)

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“…The fact that E. multilocularis and E. granulosus, like other parasitic flatworms, cannot de novo synthesize cholesterol and the majority of other lipid components, has already been firmly established by previous studies (19,20,35). This is supported by our own analyses of the first draft version of the E. multilocularis genome, which showed that genes for the majority of enzymes that are involved in cholesterol synthesis in other organisms (51) are absent in the cestode (data not shown).…”

Section: Discussionmentioning

confidence: 70%

“…As a consequence, they have to take up host-derived lipids during an infection. Particularly in the case of cholesterol, Frayha (19,20) already demonstrated that this compound cannot be synthesized by both E. multilocularis and E. granulosus and that at least E. granulosus incorporates radioactively labeled, hostderived cholesterol during experimental infection of mice. Although several Echinococcus proteins with fatty acid and hydrophobic ligand binding properties have been reported (12,25), none of these displayed cholesterol binding activities nor has, as yet, any cestode molecule been identified that interacts with components of the host's cholesterol transport machinery.…”

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confidence: 99%

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Molecular Characterization of EmABP, an Apolipoprotein A-I Binding Protein Secreted by the Echinococcus multilocularis Metacestode

Bernthaler

Epping

Schmitz³

et al. 2009

Infect Immun

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Cestodes are unable to synthesize de novo most of their own membrane lipids, including cholesterol, and have to take them up from the host during an infection. The underlying molecular mechanisms are so far unknown. Here we report the identification and characterization of a novel gene, Emabp, which is expressed by larval stages and adults of the fox tapeworm Echinococcus multilocularis. The encoded protein, EmABP, displays significant homologies to apolipoprotein A-I binding protein (AI-BP) of mammalian origin and to metazoan YjeF_N domain proteins. Like mammalian AI-BP, EmABP carries an export-directing signal sequence which is absent in predicted AI-BP orthologs from the related flatworms Schistosoma japonicum and Schmidtea mediterranea. Using a specific antibody and immunoprecipitation techniques, we demonstrate that EmABP is secreted into the extraparasitic environment and into the hydatid fluid of in vitro-cultivated metacestode vesicles. Furthermore, we show that apolipoprotein A-I (apoA-I), a major constituent of cholesterol-transporting high-density lipoproteins, is present in hydatid fluid. By pulldown experiments, we demonstrate that recombinantly expressed, purified EmABP interacts with purified human apoA-I and is able to precipitate apoA-I from human serum. On the basis of these features and the suggested function of AI-BP in cholesterol transport in higher eukaryotes, we propose a role for EmABP in cholesterol and lipid uptake mechanisms of larval E. multilocularis.

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Section: Discussionmentioning

confidence: 70%

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confidence: 99%

Molecular Characterization of EmABP, an Apolipoprotein A-I Binding Protein Secreted by the Echinococcus multilocularis Metacestode

Bernthaler

Epping

Schmitz³

et al. 2009

Infect Immun

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“…In this context is important to highlight that no enzymes for either fatty acid anabolism or squalene synthesis (the precursor of the whole family of animal sterols) have been found in the E. granulosus transcriptome (data base http://www.compsysbio.org/partigene/) or the Echinococcus multilocularis genome (unpublished observations, http://www.genedb.org/Homepage/Emultilocularis). In addition, metabolic studies have demonstrated that sterol synthesis in E. granulosus seems to stop at the level of farnesyl or nerolidol pyrophosphate and that the content of cholesterol in HCF derives from the cholesterol pool of the host [51], [52]. Thus, E. granulosus needs to take these lipids from its host.…”

Section: Discussionmentioning

confidence: 99%

Characterisation of the Native Lipid Moiety of Echinococcus granulosus Antigen B

et al. 2012

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Antigen B (EgAgB) is the most abundant and immunogenic antigen produced by the larval stage (metacestode) of Echinococcus granulosus. It is a lipoprotein, the structure and function of which have not been completely elucidated. EgAgB apolipoprotein components have been well characterised; they share homology with a group of hydrophobic ligand binding proteins (HLBPs) present exclusively in cestode organisms, and consist of different isoforms of 8-kDa proteins encoded by a polymorphic multigene family comprising five subfamilies (EgAgB1 to EgAgB5). In vitro studies have shown that EgAgB apolipoproteins are capable of binding fatty acids. However, the identity of the native lipid components of EgAgB remains unknown. The present work was aimed at characterising the lipid ligands bound to EgAgB in vivo. EgAgB was purified to homogeneity from hydatid cyst fluid and its lipid fraction was extracted using chloroform∶methanol mixtures. This fraction constituted approximately 40–50% of EgAgB total mass. High-performance thin layer chromatography revealed that the native lipid moiety of EgAgB consists of a variety of neutral (mainly triacylglycerides, sterols and sterol esters) and polar (mainly phosphatidylcholine) lipids. Gas-liquid chromatography analysis showed that 16∶0, 18∶0 and 18∶1(n-9) are the most abundant fatty acids in EgAgB. Furthermore, size exclusion chromatography coupled to light scattering demonstrated that EgAgB comprises a population of particles heterogeneous in size, with an average molecular mass of 229 kDa. Our results provide the first direct evidence of the nature of the hydrophobic ligands bound to EgAgB in vivo and indicate that the structure and composition of EgAgB lipoprotein particles are more complex than previously thought, resembling high density plasma lipoproteins. Results are discussed considering what is known on lipid metabolism in cestodes, and taken into account the Echinococcus spp. genomic information regarding both lipid metabolism and the EgAgB gene family.

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“…Like other cestodes, Echinococcus is not able to synthesize most of their own lipids de novo and therefore, the lipids from the host origin were taken up by the parasite for their survival (Smyth & McManus, 1989). Furthermore, the phospholipids of host origin in Hymenilepis diminuta (Ginger & Fairbairn, 1966) and the lack of de novo synthesis of cholesterol in larval cestodes (Frayha, 1968(Frayha, , 1974, suggests that these fractions in the cyst wall may also be of host origin. The high level of phospholipids in both types of cyst walls indicated their possible involvement in the reorganization and synthesis of membrane during growth of the cysts The differential distribution of phospholipid fractions, lysophosphatidylethanolamine and phosphatidylethanolamine in the fertile cyst wall as observed in the present study have also been recorded in higher concentration in other helminthes (Barrett, 1981, Abidi et al, 1989, whereas sphingomyelin and phosphatidylcholine were higher in the sterile cyst wall.…”

Section: Discussionmentioning

confidence: 99%

Comparative studies on the biochemical composition and polypeptide profiles of the cyst walls from sterile and fertile hydatid cysts of Echinococcus granulosus from buffalo host

Irshadullah

Rani

2011

Helminthologia

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88 SummaryIn the present study, biochemical composition and polypeptide profiles of the cyst walls of sterile and fertile hydatid cyst, collected from the lungs of naturally infected Bubalus bubalis have been investigated. Significant quantitative differences in various biochemical components as well as in protein banding patterns were observed between the two types of cyst walls, suggesting variations in their metabolic states. The cyst wall collected from fertile cysts had significantly less glycogen, lipids and triglycerides but more RNA and DNA as compared to sterile cyst wall. Among phospholipid fractions, lysophosphatidylethanolamine and phosphatidylethanolamine were significantly higher in the fertile, whereas, sphingomyelin showed higher values in the sterile cyst wall. The numbers of polypeptides resolved in the fertile cyst wall were more than those in sterile cyst wall possibly due to the presence of extra proteins required for production of brood capsules and protoscoleces. Detection of more polypeptides by silver than CBBR-250 staining could be due to high sensitivity of silver stain which also detects conjugated proteins such as lipo-, phospho-and glycoproteins. The characteristic polypeptides specific to either types of the cyst wall have the potential to be exploited for diagnostics.

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A study on the synthesi and absorption of cholesterol in hydatid cysts (Echinococcus granulosus)

Cited by 30 publications

References 10 publications

Molecular Characterization of EmABP, an Apolipoprotein A-I Binding Protein Secreted by the Echinococcus multilocularis Metacestode

Molecular Characterization of EmABP, an Apolipoprotein A-I Binding Protein Secreted by the Echinococcus multilocularis Metacestode

Characterisation of the Native Lipid Moiety of Echinococcus granulosus Antigen B

Comparative studies on the biochemical composition and polypeptide profiles of the cyst walls from sterile and fertile hydatid cysts of Echinococcus granulosus from buffalo host

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