| 1. |
- Gong, Feng, et al.
(författare)
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Processing of macromolecular heparin by heparanase
- 2003
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 278:37, s. 35152-35158
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Tidskriftsartikel (refereegranskat)abstract
- Heparanase is an endo-glucuronidase expressed in a variety of tissues and cells that selectively cleaves extracellular and cell-surface heparan sulfate. Here we propose that this enzyme is involved also in the processing of serglycin heparin proteoglycan in mouse mast cells. In this process, newly synthesized heparin chains (60-100 kDa) are degraded to fragments (10-20 kDa) similar in size to commercially available heparin (Jacobsson, K. G., and Lindahl, U. (1987) Biochem. J. 246, 409-415). A fraction of these fragments contains the specific pentasaccharide sequence required for high affinity binding to antithrombin implicated with anticoagulant activity. Rat skin heparin, which escapes processing in vivo, was used as a substrate in reaction with recombinant human heparanase. An incubation product of commercial heparin size retained the specific pentasaccharide sequence, although oligosaccharides (3-4 kDa) containing this sequence could be degraded by the same enzyme. Commercial heparin was found to be a powerful inhibitor (I50 approximately 20 nM expressed as disaccharide unit, approximately 0.7 nM polysaccharide) of heparanase action toward antithrombin-binding oligosaccharides. Cells derived from a serglycin-processing mouse mastocytoma expressed a protein highly similar to other mammalian heparanases. These findings strongly suggest that the intracellular processing of the heparin proteoglycan polysaccharide chains is catalyzed by heparanase, which primarily cleaves target structures distinct from the antithrombin-binding sequence.
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| 2. |
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| 3. |
- Jendresen, Charlotte B., et al.
(författare)
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Overexpression of Heparanase Lowers the Amyloid Burden in Amyloid-beta Precursor Protein Transgenic Mice
- 2015
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 290:8, s. 5053-5064
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Tidskriftsartikel (refereegranskat)abstract
- Heparan sulfate (HS) and HS proteoglycans (HSPGs) colocalize with amyloid-beta (A beta) deposits in Alzheimer disease brain and in A beta precursor protein (A beta PP) transgenic mouse models. Heparanase is an endoglycosidase that specifically degrades the unbranched glycosaminoglycan side chains of HSPGs. The aim of this study was to test the hypothesis that HS and HSPGs are active participators of A beta pathogenesis in vivo. We therefore generated a double-transgenic mouse model overexpressing both human heparanase and human A beta PP harboring the Swedish mutation (tgHpa*Swe). Overexpression of heparanase did not affect A beta PP processing because the steady-state levels of A beta(1-40), A beta(1-42), and soluble A beta PP beta were the same in 2- to 3-month-old double-transgenic tgHpa*Swe and single-transgenic tgSwe mice. In contrast, the Congo red-positive amyloid burden was significantly lower in 15-month-old tgHpa*Swe brain than in tgSwe brain. Likewise, the A beta burden, measured by A beta(x-40) and A beta(x-42) immunohistochemistry, was reduced significantly in tgHpa*Swe brain. The intensity of HS-stained plaques correlated with the A beta(x-42) burden and was reduced in tgHpa*Swe mice. Moreover, the HS-like molecule heparin facilitated A beta(1-42)-aggregation in an in vitro Thioflavin T assay. The findings suggest that HSPGs contribute to amyloid deposition in tgSwe mice by increasing A beta fibril formation because heparanase-induced fragmentation of HS led to a reduced amyloid burden. Therefore, drugs interfering with A beta-HSPG interactions might be a potential strategy for Alzheimer disease treatment.
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| 4. |
- Jia, Juan, et al.
(författare)
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Lack of L-iduronic acid in heparan sulfate affects interaction with growth factors and cell signaling
- 2009
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 284:23, s. 15942-15950
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Tidskriftsartikel (refereegranskat)abstract
- Glucuronyl C5-epimerase (Hsepi) catalyzes the conversion of D-glucuronic acid to L-iduronic acid in heparan sulfate (HS) biosynthesis. Disruption of the Hsepi gene in mouse yielded a lethal phenotype with selective organ defects, but had remarkably little effect on other organ systems. We have approached the underlying mechanisms by examining the course and effects of FGF2 signaling in a mouse embryonic fibroblast (MEF) cell line derived from the Hsepi-/- mouse. The HS produced by these cells is devoid of IdoA residues, but shows upregulated N- and 6-O-sulfation compared to wildtype (WT) MEF HS. In medium fortified with 10% FCS the Hsepi-/- MEFs proliferated and migrated similar to WT cells. Under starvation conditions both cell types showed attenuated proliferation and migration, that could be restored by addition of FGF2 to WT cells whereas Hsepi-/- cells were resistant. Moreover, ERK phosphorylation following FGF2 stimulation was delayed in Hsepi-/- compared to WT cells. Assessment of HS-growth factor interaction by nitrocellulose filter trapping revealed strikingly aberrant binding property of FGF2 and glia-derived neurotropic factor (GDNF) to Hsepi-/- but not to WT HS. GDNF has a key role in kidney development, defective in Hsepi-/- mice. By contrast, Hsepi-/- and WT HS interacted similarly and in conventional mode with FGF10. These findings correlate defective function of growth factors with their mode of HS interaction, and may help explain the partly modest organ phenotypes observed after genetic ablation of selected enzymes in HS biosynthesis.
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| 5. |
- Kurup, Sindhulakshmi, et al.
(författare)
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Characterization of anti-heparan sulfate phage display antibodies AO4B08 and HS4E4
- 2007
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 282:29, s. 21032-21042
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Tidskriftsartikel (refereegranskat)abstract
- Heparan sulfates (HS) are linear carbohydrate chains, covalently attached to proteins, that occur on essentially all cell surfaces and in extracellular matrices. HS chains show extensive structural heterogeneity and are functionally important during embryogenesis and in homeostasis due to their interactions with various proteins. Phage display antibodies have been developed to probe HS structures, assess the availability of protein-binding sites, and monitor structural changes during development and disease. Here we have characterized two such antibodies, AO4B08 and HS4E4, previously noted for partly differential tissue staining. AO4B08 recognized both HS and heparin, and was found to interact with an ubiquitouys, N-, 2-O-, and 6-O-sulfated saccharide motif, including an internal 2-O-sulfate group. HS4E4 turned out to preferentially recognize low-sulfated HS motifs containing iduronic acid, and N-sulfated as well as N-acetylated glucosamine residues. Contrary to AO4B08, HS4E4 did not bind highly O-sulfated structures such as found in heparin.
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| 6. |
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| 7. |
- Li, Jin-Ping, et al.
(författare)
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Biosynthesis of heparin / heparan sulfate : cDNA cloning and expression of D-glucuronyl C5-epimerase from bovine lung
- 1997
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Ingår i: Journal of Biological Chemistry. - : Elsevier BV. - 0021-9258 .- 1083-351X. ; 272:44, s. 28158-28163
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Tidskriftsartikel (refereegranskat)abstract
- Glucuronyl C5-epimerases catalyze the conversion of D-glucuronic acid (GlcUA) to L-iduronic acid (IdceA) units during the biosynthesis of glycosaminoglycans. An epimerase implicated in the generation of heparin/heparan sulfate was previously purified to homogeneity from bovine liver (Campbell, P., Hannesson, H. H., Sandbäck, D., Rodén, L., Lindahl, U., and Li, J.-p. (1994) J. Biol. Chem. 269, 26953-26958). The present report describes the molecular cloning and functional expression of the lung enzyme. The cloned enzyme contains 444 amino acid residues and has a molecular mass of 49,905 Da. N-terminal sequence analysis of the isolated liver enzyme showed this species to be a truncated form lacking a 73-residue N-terminal domain of the deduced amino acid sequence. The coding cDNA insert was cloned into a baculovirus expression vector and expressed in Sf9 insect cells. Cells infected with recombinant epimerase showed a 20-30-fold increase in enzyme activity, measured as release of 3H2O from a polysaccharide substrate containing C5-3H-labeled hexuronic acid units. Furthermore, incubation of the expressed protein with the appropriate (GlcUA-GlcNSO3)n substrate resulted in conversion of approximately 20% of the GlcUA units into IdceA residues. Northern analysis implicated two epimerase transcripts in both bovine lung and liver tissues, a dominant approximately 9-kilobase (kb) mRNA and a minor approximately 5-kb species. Mouse mastocytoma cells showed only the approximately 5-kb transcript. A comparison of the cloned epimerase with the enzymes catalyzing an analogous reaction in alginate biosynthesis revealed no apparent amino acid sequence similarity.
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| 8. |
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| 9. |
- Noborn, Fredrik, et al.
(författare)
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Heparan sulfate/heparin-HDL interaction dissociates serum amyloid A (SAA) from HDL-SAA complex leading to SAA aggregation
- 2012
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:30, s. 25669-25677
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation-related (AA) amyloidosis is a severe clinical disorder characterized by the systemic deposition of the acute-phase reactant serum amyloid A (SAA). SAA is normally associated with the high-density lipoprotein (HDL) fraction in plasma, but under yet unclear circumstances, the apolipoprotein is converted into amyloid fibrils. AA amyloid and heparan sulfate (HS) display an intimate relationship in situ, suggesting a role for HS in the pathogenic process. This study reports that HS dissociates SAA from HDLs isolated from inflamed mouse plasma. Application of surface plasmon resonance spectroscopy and molecular modeling suggests that HS simultaneously binds to two apolipoproteins of HDL, SAA and ApoA-I, and thereby induce SAA dissociation. The activity requires a minimum chain length of 12-14 sugar units, proposing an explanation to previous findings that short HS fragments preclude AA amyloidosis. The results address the initial events in the pathogenesis of AA amyloidosis.
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| 10. |
- O'Callaghan, Paul, et al.
(författare)
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Microglial Heparan Sulfate Proteoglycans Facilitate the Cluster-of-Differentiation 14 (CD14)/Toll-like Receptor 4 (TLR4)-Dependent Inflammatory Response
- 2015
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 290:24, s. 14904-14914
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Tidskriftsartikel (refereegranskat)abstract
- Microglia rapidly mount an inflammatory response to pathogens in the central nervous system (CNS). Heparan sulfate proteoglycans (HSPGs) have been attributed various roles in inflammation. To elucidate the relevance of microglial HSPGs in a pro-inflammatory response we isolated microglia from mice overexpressing heparanase (Hpa-tg), the HS-degrading endoglucuronidase, and challenged them with lipopolysaccharide (LPS), a bacterial endotoxin. Prior to LPS-stimulation, the LPS-receptor cluster-of-differentiation 14 (CD14) and Toll-like receptor 4 (TLR4; essential for the LPS response) were similarly expressed in Ctrl and Hpa-tg microglia. However, compared with Ctrl microglia, Hpa-tg cells released significantly less tumor necrosis factor-α (TNFα), essentially failed to up-regulate interleukin-1β (IL1β) and did not initiate synthesis of proCD14. Isolated primary astroyctes expressed TLR4, but notably lacked CD14 and in contrast to microglia, LPS challenge induced a similar TNFα response in Ctrl and Hpa-tg astrocytes, while neither released IL1β. The astrocyte TNFα-induction was thus attributed to CD14-independent TLR4 activation and was unaffected by the cells HS status. Equally, the suppressed LPS-response in Hpa-tg microglia indicated a loss of CD14-dependent TLR4 activation, suggesting that microglial HSPGs facilitate this process. Indeed, confocal microscopy confirmed interactions between microglial HS and CD14 in LPS-stimulated microglia and a potential HS-binding motif in CD14 was identified. We conclude that microglial HSPGs facilitate CD14-dependent TLR4 activation and that heparanase can modulate this mechanism.
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