| 1. |
- Deligny, Audrey, et al.
(author)
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NDST2 (N-Deacetylase/N-Sulfotransferase-2) Enzyme Regulates Heparan Sulfate Chain Length
- 2016
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 291:36, s. 18600-18607
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Journal article (peer-reviewed)abstract
- Analysis of heparan sulfate synthesized by HEK 293 cells overexpressing murine NDST1 and/or NDST2 demonstrated that the amount of heparan sulfate was increased in NDST2-but not in NDST1-overexpressing cells. Altered transcript expression of genes encoding other biosynthetic enzymes or proteoglycan core proteins could not account for the observed changes. However, the role of NDST2 in regulating the amount of heparan sulfate synthesized was confirmed by analyzing heparan sulfate content in tissues isolated from Ndst2(-/-) mice, which contained reduced levels of the polysaccharide. Detailed disaccharide composition analysis showed no major structural difference between heparan sulfate from control and Ndst2(-/-) tissues, with the exception of heparan sulfate from spleen where the relative amount of trisulfated disaccharides was lowered in the absence of NDST2. In vivo transcript expression levels of the heparan sulfate-polymerizing enzymes Ext1 and Ext2 were also largely unaffected by NDST2 levels, pointing to a mode of regulation other than increased gene transcription. Size estimation of heparan sulfate polysaccharide chains indicated that increased chain lengths in NDST2-overexpressing cells alone could explain the increased heparan sulfate content. A model is discussed where NDST2-specific substrate modification stimulates elongation resulting in increased heparan sulfate chain length.
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| 3. |
- Magalhaes, Ana, et al.
(author)
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The glycan receptors of Helicobacter pylori : decoding the pathways underlying gastric glycophenotype modulation
- 2016
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In: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 26:12, s. 1401-1402
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Journal article (peer-reviewed)abstract
- The gastrointestinal tract is covered by a complex extracellular mucus layer that protects the gastric epithelium fromexternal aggressions such as chemical agents, microorganismsand shear stress. Although this mucus barrier confers protec-tion against certain pathogens, it may also provide a niche formicrobial binding.Helicobacter pyloriexploits the host glycoconjugates present in the gastric mucus layer and lining thesurface epithelium of the gastric mucosa to colonize the stomach. Infection can persist for decades promoting chronicinflammation, and in a subset of individuals lesions cansilently progress to cancer. The secreted MUC5AC mucin isthe main component of the gastric mucus layer, andH. pyloriBabA-mediated binding to MUC5AC confers increased riskfor overt disease. We have shown that FUT2 determines theO-glycosylation pattern of Muc5ac, with Fut2 knock-outleading to a marked decrease inα1,2-fucosylated structuresand increased expression of the terminal type 1 glycan structure Lewisa. Importantly, for thefirst time, we structurallyvalidated the expression of Lewisain murine gastric mucosa(1). We further demonstrated that loss of mucin FUT2-mediated fucosylation impairs gastric mucosal binding ofH.pyloriBabA adhesin, which is a recognized feature of patho-genicity. UponH. pyloriinfection,concomitantly with tissueinflammation, there is a remodeling of the gastric glycopheno-type. We showed that increased expression of sialyl-Lewisa/xantigens is due to transcriptional up-regulation of theB3GNT5,B3GALT5,andFUT3genes. In addition, weobserved thatH. pyloriinfected individuals present a markedgastric local pro-inflammatory signature with significantlyhigher TNF-αlevels and demonstrated that TNF-induced activation of the NF-kappaB pathway results in B3GNT5 up-regulation (2). Furthermore, we showed that this gastric glycosylation shift, characterized by increased sialylation pat-terns, favors SabA-mediatedH. pyloriattachment to humaninflamed gastric mucosa. Our data provides clinically relevantinsights into the regulatory mechanisms underlyingH. pylorimodulation of host glycosylation machinery, and phenotypicalterations crucial for life-long infection and gastric disease.
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