Unique precipitation and exocytosis of a calcium salt of <i>myo</i>‐inositol hexakisphosphate in larval <i>Echinococcus granulosu</i>s

Irigoı́n, Florencia; Casaravilla, Cecilia; Iborra, Francisco J.; Sim, Robert B.; Ferreira, Fernando; Díaz, Álvaro

doi:10.1002/jcb.20262

Cited by 34 publications

(39 citation statements)

References 20 publications

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“…Ins P 6 binds strongly to Ca 2+ , and its solubility limit in the presence of millimolar levels of Ca 2+ is less than 1 μM [36,38]. However, the (insoluble) Ca 2+ salt of Ins P 6 has been found to exist naturally, for example, as a component of the extracellular coat around the parasitic cestode Echinococcus granulosus [45] to which it can be transported as nanometre diameter granules [46]. From these observations, it seems that the most plausible mechanism for cellular Ins P 6 uptake is endocytotic absorption (possibly as a Ca 2+ –Ins P 6 precipitate), accompanied by dephosphorylation within the cell.…”

Section: Discussionmentioning

confidence: 99%

Do mammals make all their own inositol hexakisphosphate?

Letcher

Schell

Irvine

2008

Biochemical Journal

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A highly specific and sensitive mass assay for inositol hexakisphosphate (InsP6) was characterized. This centres around phosphorylating InsP6 with [32P]ATP using a recombinant InsP6 kinase from Giardia lambia, followed by HPLC of the 32P-labelled products with an internal [3H]InsP7 standard. This assay was used to quantify InsP6 levels in a variety of biological samples. Concentrations of InsP6 in rat tissues varied from 10–20 μM (assuming 64% of wet weight of tissue is cytosol water), whereas using the same assumption axenic Dictyostelium discoideum cells contained 352±11 μM InsP6. HeLa cells were seeded at low density and grown to confluence, at which point they contained InsP6 levels per mg of protein similar to rat tissues. This amounted to 1.952±0.117 nmol InsP6 per culture dish, despite the cells being grown in serum shown to contain no detectable (less than 20 pmol per dish) InsP6. These results demonstrate that mammalian cells synthesize all their own InsP6. Human blood was analysed, and although the white cell fraction contained InsP6 at a concentration comparable with other tissues, in serum and platelet-free plasma no InsP6 was detected (<1 nM InsP6). Human urine was also examined, and also contained no detectable (<5 nM) InsP6. These results suggest that dietary studies purporting to measure InsP6 at micromolar concentrations in human plasma or urine may not have been quantifying this inositol phosphate. Therefore claims that administrating InsP6 in the diet or applying it topically can produce health benefits by increasing extracellular InsP6 levels may require reassessment.

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Section: Discussionmentioning

confidence: 99%

Do mammals make all their own inositol hexakisphosphate?

Letcher

Schell

Irvine

2008

Biochemical Journal

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“…The resulting fine powders were carefully rehydrated in pyrogen-free PBS containing 30 mM EDTA (1 ml for every 2 mg dry mass) to extract the calcium Ins P 6 deposits (10), sequentially filtered through 85- and 23-μm gauze, and then extensively washed in pyrogen-free PBS, with centrifuging at 3,000 × g for 5 min each time. The dehydration was carried out either with ethanol and acetone as described previously (9) (EA-pLL) or by freeze-drying (FD-pLL). In addition, we tested pLL prepared by a method that did not involve a dehydration step, namely, shredding with a Tissue-ruptor blender (Qiagen) and then applying mild sonication (SS-pLL).…”

Section: Methodsmentioning

confidence: 99%

“…In E. granulosus, but probably not in the other species, the LL additionally contains dispersed nanodeposits of the calcium salt of inositol hexakisphosphate (8–10). The mucin backbones, deduced from the germinal layer transcriptome (2, 11, 12), comprise highly glycosylated domains and short nonglycosylated N-terminal extensions.…”

Section: Introductionmentioning

confidence: 99%

Unconventional Maturation of Dendritic Cells Induced by Particles from the Laminated Layer of Larval Echinococcus granulosus

et al. 2014

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The larval stage of the cestode parasite Echinococcus granulosus causes hydatid disease in humans and livestock. This infection is characterized by the growth in internal organ parenchymae of fluid-filled structures (hydatids) that elicit surprisingly little inflammation in spite of their massive size and persistence. Hydatids are protected by a millimeter-thick layer of mucin-based extracellular matrix, termed the laminated layer (LL), which is thought to be a major factor determining the host response to the infection. Host cells can interact both with the LL surface and with materials that are shed from it to allow parasite growth. In this work, we analyzed the response of dendritic cells (DCs) to microscopic pieces of the native mucin-based gel of the LL (pLL). In vitro, this material induced an unusual activation state characterized by upregulation of CD86 without concomitant upregulation of CD40 or secretion of cytokines (interleukin 12 [IL-12], IL-10, tumor necrosis factor alpha [TNF-α], and IL-6). When added to Toll-like receptor (TLR) agonists, pLL-potentiated CD86 upregulation and IL-10 secretion while inhibiting CD40 upregulation and IL-12 secretion. In vivo, pLL also caused upregulation of CD86 and inhibited CD40 upregulation in DCs. Contrary to expectations, oxidation of the mucin glycans in pLL with periodate did not abrogate the effects on cells. Reduction of disulfide bonds, which are known to be important for LL structure, strongly diminished the impact of pLL on DCs without altering the particulate nature of the material. In summary, DCs respond to the LL mucin meshwork with a “semimature” activation phenotype, both in vitro and in vivo.

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“…Treating E. granulosus HW with calcium chelators dissolves the calcium InsP 6 deposits (Irigoín et al 2002(Irigoín et al , 2004. Being initially interested in proteins associated with these deposits, we prepared extracts using EGTA-or EDTA-containing buffer from intact hydatids obtained by experimental infection of mice.…”

Section: R E S U L T Smentioning

confidence: 99%

Phagocyte-specific S100 proteins in the local response to theEchinococcus granulosuslarva

et al. 2012

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SUMMARYInfection by larvalEchinococcus granulosusis usually characterized by tight inflammatory control. However, various degrees of chronic granulomatous inflammation are also observed, reaching a high point in infection of cattle by the most prevalent parasite strain worldwide, which is not well adapted to this host species. In this context, epithelioid and multinucleated giant macrophages surround the parasite, and the secreted products of these cells often associate with the larval wall. The phagocyte-specific S100 proteins, S100A8, S100A9 and S100A12, are important non-conventionally secreted amplifiers of inflammatory responses. We have analysed by proteomics and immunohistochemistry the presence of these proteins at theE. granulosuslarva-host interface. We found that, in the context of inflammatory control as observed in human infections, the S100 proteins are not abundant, but S100A9 and S100A8 can be expressed by eosinophils distal to the parasite. In the granulomatous inflammation context as observed in cattle infections, we found that S100A12 is one of the most abundant host-derived, parasite-associated proteins, while S100A9 and S100A8 are not present at similarly high levels. As expected, S100A12 derives mostly from the epithelioid and multinucleated giant cells. S100A12, as well as cathepsin K and matrix metalloproteinase-9, also expressed byE. granulosus-elicited epithelioid cells, are connected to the Th17 arm of immunity, which may therefore be involved in this granulomatous response.

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Unique precipitation and exocytosis of a calcium salt of myo‐inositol hexakisphosphate in larval Echinococcus granulosus

Cited by 34 publications

References 20 publications

Do mammals make all their own inositol hexakisphosphate?

Do mammals make all their own inositol hexakisphosphate?

Unconventional Maturation of Dendritic Cells Induced by Particles from the Laminated Layer of Larval Echinococcus granulosus

Phagocyte-specific S100 proteins in the local response to theEchinococcus granulosuslarva

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