scholarly journals Structure and metabolism of sulphated glycosaminoglycans in cultures of human fibroblasts. Structural characteristics of co-polymeric galactosaminoglycans in sequential extracts of fibroblasts during pulse-chase experiments

1979 ◽  
Vol 178 (2) ◽  
pp. 257-270 ◽  
Author(s):  
I Sjöberg ◽  
I Carlstedt ◽  
L Cöster ◽  
A Malmström ◽  
L A Fransson

1. Human embryonic lung and skin fibroblasts were allowed to incorporate 32SO42- or 35SO42- and D-[1-3H]glucosamine. After removal of the medium the monolayer was subjected to sequential extractions by using EDTA, brief trypsin digestion, extraction with dithiothreitol ofllowed by freeze–thawing and extraction with trichloroacetic acid. The heparan sulphate and galactosaminoglycan contents of the various extracts were estimated after deaminative cleavage of the former component. Heparan sulphate was the major component of the trypsin digest, whereas galactosaminoglycans were the dominant component of other fractions. 2. Galactosaminoglycans of the various fractions were subjected to chemical (periodate oxidation/alkaline elimination) and enzymic (chondroitinase-AC and -ABC, as well as testicular hyaluronidase) degradations. Galactosaminoglycans from the insoluble cell fraction and the dithiothreitol extract contained larger amounts of L-iduronic acid than did those of other fractions. 3. Pulse-chase experiments were performed with and without replating of the cells at the start of the chase period. Radioactive glycans were isolated from the various extracts during the chase period. The half-lives of glycans of the insoluble cell fraction and the dithioreitol extract were shorter (5–8h) than were those of the trypsin digest and the EDTA extract (22h and 11h respectively). After replating of the cells in chase medium, radioactive cell-associated glycans were secreted from the cells and could be recovered in the trypsin digest, the EDTA extract and the medium. Furthermore, 35S/3H ratios of glycans from all these fractions decreased during the chase period. The following conclusions were reached. The insoluble cell fraction contains the synthesis pool and some structural material, whereas the soluble cell fraction is the storage and degradation pool. The dithiothreitol extract appears to contain the immediate precursors of secreted material. The trypsin-released glycans comprise structural components as well as material destined for pinocytosis or secretion into the medium. The EDTA extract is considered to consist of glycans en route to the medium. 4. The two presumptive precursor pools were preferentially depleted of L-iduronic acid-rich galactosaminoglycans during the chase. Glycans recovered from the trypsin digest, the EDTA extract and the medium during the chase contained larger amounts of periodate-resistant uronic acid residues (D-glucuronic acid and/or L-iduronic acid O-sulphate) than did their precursors. It is proposed that polymer-level modifications of secreted glycans are partly responsible for the results.

1977 ◽  
Vol 167 (2) ◽  
pp. 383-392 ◽  
Author(s):  
Ingrid Sjöberg ◽  
Lars-Åke Fransson

Foetal human lung fibroblasts, grown in monolayer, were allowed to incorporate 35SO42− for various periods of time. 35S-labelled macromolecular anionic products were isolated from the medium, a trypsin digest of the cells in monolayer and the cell residue. The various radioactive polysaccharides were identified as heparan sulphate and a galactosaminoglycan population (chondroitin sulphate and dermatan sulphate) by ion-exchange chromatography and by differential degradations with HNO2 and chondroitinase ABC. Most of the heparan sulphate was found in the trypsin digest, whereas the galactosaminoglycan components were largely confined to the medium. Electrophoretic studies on the various 35S-labelled galactosaminoglycans suggested the presence of a separate chondroitin sulphate component (i.e. a glucuronic acid-rich galactosaminoglycan). The 35S-labelled galactosaminoglycans were subjected to periodate oxidation of l-iduronic acid residues followed by scission in alkali. A periodate-resistant polymer fraction was obtained, which could be degraded to disaccharides by chondroitinase AC. However, most of the 35S-labelled galactosaminoglycans were extensively degraded by periodate oxidation–alkaline elimination. The oligosaccharides obtained were essentially resistant to chondroitinase AC, indicating that the iduronic acid-rich galactosaminoglycans (i.e. dermatan sulphate) were composed largely of repeating units containing sulphated or non-sulphated l-iduronic acid residues. The l-iduronic acid residues present in dermatan sulphate derived from the medium and the trypsin digest contained twice as much ester sulphate as did material associated with the cells. The content of d-glucuronic acid was low and similar in all three fractions. The relative distribution of glycosaminoglycans among the various fractions obtained from cultured lung fibroblasts was distinctly different from that of skin fibroblasts [Malmström, Carlstedt, Åberg & Fransson (1975) Biochem. J.151, 477–489]. Moreover, subtle differences in co-polymeric structure of dermatan sulphate isolated from the two cell types could be detected.


1980 ◽  
Vol 191 (1) ◽  
pp. 103-110 ◽  
Author(s):  
Ingrid Sjöberg ◽  
Lars-Ȧke Fransson

1. 3H- and 35S-labelled heparan sulphate was isolated from monolayers of human lung fibroblasts and subjected to degradations by (a) deaminative cleavage and (b) periodate oxidation/alkaline elimination. Fragments were resolved by gel- and ion-exchange-chromatography. 2. Deaminative cleavage of the radioactive glycan afforded mainly disaccharides with a low content of ester-sulphate and free sulphate, indicating that a large part (approx. 80%) of the repeating units consisted of uronosyl-glucosamine-N-sulphate. Blocks of non-sulphated [glucuronosyl-N-acetyl glucosamine] repeats (3–4 consecutive units) accounted for the remainder of the chains. 3. By selective oxidation of glucuronic acid residues associated with N-acetylglucosamine, followed by scission in alkali, the radioactive glycan was degraded into a series of fragments. The glucuronosyl-N-acetylglucosamine-containing block regions yielded a compound N-acetylglucosamine–R, where R is the remnant of an oxidized and degraded glucuronic acid. Periodate-insensitive uronic acid residues were recovered in saccharides of the general structure glucosamine–(uronic acid–glucosamine)n–R. 4. Further degradations of these saccharides via deaminative cleavage and re-oxidations with periodate revealed that iduronic acid may be located in sequences such as glucosamine-N-sulphate→iduronic acid→N-acetylglucosamine. Occasionally the iduronic acid was sulphated. Blocks of iduronic acid-containing repeats may contain up to five consecutive units. Alternating arrangements of iduronic acid- and glucuronic acid-containing repeats were also observed. 5. 3H- and 35S-labelled heparan sulphates from sequential extracts of fibroblasts (medium, EDTA, trypsin digest, dithiothreitol extract, cell-soluble and cell-insoluble material) afforded similar profiles after both periodate oxidation/alkaline elimination and deaminative cleavage.


1975 ◽  
Vol 151 (3) ◽  
pp. 477-489 ◽  
Author(s):  
A Malström ◽  
I Carlstedt ◽  
L Åberg ◽  
L Å Fransson

The structure of dermatan [35S]sulphate-chondroitin [35S]sulphate copolymers synthesized and secreted by fibroblasts in culture was studied. 35S-labelled glycosaminoglycans were isolated from the medium, a trypsin digest of the cells and the cell residue after 72h of 35SO42-incorporation. The galactosaminoglycan component (dermatan sulphatechondroitin sulphate copolymers) was isolated and subjected to various degradation procedures including digestion with testicular hyaluronidase, chondroitinase-AC and-ABC and periodate oxidation followed by alkaline elimination. The galactosaminoglycans from the various sources displayed significant structural differences with regard to the distribution of various repeating units, i.e. IdUA-GalNAc-SO4 (L-iduronic acid-N-acetyl-galactosamine sulphate), GlcUA-GalNAc-SO4 (D-glucuronic acid-N-acetylgalactosamine-sulphate) and IdUA(-SO4)-GalNAc (L-iduronosulphate-N-acetylgalactosamine). The galactosaminoglycans of the cell residue contained larger amounts of IdUA-GalNAc-SO4 than did those isolated from the medium or those released by trypsin. In contrast, the glycans from the latter 2 sources contained large proportions of periodate-resistant repeat periods [GlcUA-GalNAc-SO4 and IdUA(-SO4)-GalNAc]. Periods containing L-iduronic acid sulphate were particularly prominent in copolymers found in the medium. Kinetic studies indicated that the 35S-labelled glycosaminoglycan of the cell residue accumulated radioactivity more slowly than did the glycans of other fractions, indicating that the material remaining with the cells was not exclusively a precursor of the secreted polymers. The presence of copolymers rich in glucuronic acid or iduronic acid sulphate residues in the soluble fractions may be the result of selective secretion from the cells. Alternatively, extracellular, polymer-level modifications such as C-5 inversion of L-iduronic acid to D-glucuronic acid, or sulphate rearrangements, would yield similar results.


1997 ◽  
Vol 322 (2) ◽  
pp. 499-506 ◽  
Author(s):  
Toshihiko TOIDA ◽  
Hisao YOSHIDA ◽  
Hidenao TOYODA ◽  
Ichiro KOSHIISHI ◽  
Toshio IMANARI ◽  
...  

This study presents a comparison of heparan sulphate chains isolated from various porcine and bovine tissues. 1H-NMR spectroscopy (500 MHz) was applied for structural and compositional studies on intact heparan sulphate chains. After enzymic digestion of heparan sulphate using heparin lyase I (EC 4.2.2.7) II and III (EC 4.2.2.8), the compositions of unsaturated disaccharides obtained were determined by analytical capillary electrophoresis. Correlations between the N-sulphated glucosamine residues and O-sulphation and between iduronic acid content and total sulphation were discovered using the data obtained by NMR and disaccharide analysis. Heparan sulphate chains could be classified into two groups based on the sulphation degree and the iduronic acid content. Heparan sulphate chains with a high degree of sulphation possessed also a significant number of iduronic acid residues and were isolated exclusively from porcine brain, liver and kidney medulla. The presence and amount of N-unsubstituted glucosamine residues (GlcNp) was established in all of the heparan sulphates examined. The structural context in which this residue occurs was demonstrated to be: high sulphation domain → 4)-β-d-GlcAp-(1 → 4)-α-d-GlcNp-(1 → 4)-β-d-GlcAp-(1 → low sulphation domain (where GlcNp is 2-amino-2-deoxyglucopyranose, and GlcAp is glucopyranosyluronic acid), based on the isolation and characterization of a novel, heparin lyase III-derived, GlcNp containing tetrasaccharide and hexasaccharide. The results presented suggest that structural differences may play a role in important biological events controlled by heparan sulphate in different tissues.


1974 ◽  
Vol 143 (2) ◽  
pp. 379-389 ◽  
Author(s):  
Lars-Åke Fransson ◽  
Lars Cöster ◽  
Birgitta Havsmark ◽  
Anders Malmström ◽  
Ingrid Sjöberg

Dermatan sulphate was degraded by testicular hyaluronidase and an oversulphated fraction was isolated by ion-exchange chromatography. This preparation, which contained fairly long segments derived from the non-reducing terminal portion of the molecule, was subjected to periodate oxidation under acidic conditions. The oxidized iduronic acid residues were cleaved by reduction-hydrolysis (Smith-degradation) (Fransson & Carlstedt, 1974) or by alkaline elimination. The oligosaccharides so obtained contained both GlcUA (glucuronic acid) and IdUA-SO4 (sulphated iduronic acid) residues. Copolymeric oligosaccharides obtained after alkaline elimination were cleaved by chondroitinase-AC into disaccharide and higher oligosaccharides. Since the corresponding oligosaccharides obtained by Smith-degradation were unaffected by this enzyme, it was concluded that the carbohydrate sequences were GalNAc-(IdUA-GalNAc)n-GlcUA-GalNAc. The iduronic acid-containing sequences were resistant to digestion with chondroitinase-ABC. It was demonstrated that the presence of unsulphated N-acetylgalactosamine residues in these sequences could be responsible for the observed effect. This information was obtained in an indirect way. Chemically desulphated dermatan sulphate was found to be a poor substrate for the chondroitinase-ABC enzyme. Moreover, digestion with chondroitinase-ABC of chondroitinase-AC-degraded dermatan sulphate released periodate-resistant iduronic acid-containing oligosaccharides. It is concluded that copolymeric sequences of the following structure are present in pig skin dermatan sulphate: [Formula: see text] N-acetylgalactosamine moieties surrounding IdUA-SO4 residues are unsulphated to a large extent.


1987 ◽  
Vol 245 (2) ◽  
pp. 543-550 ◽  
Author(s):  
D H Farrell ◽  
D D Cunningham

Protease nexin-1 (PN-1) is a proteinase inhibitor that is secreted by human fibroblasts in culture. PN-1 inhibits certain regulatory serine proteinases by forming a covalent complex with the catalytic-site serine residue; the complex then binds to the cell surface and is internalized and degraded. The fibroblast surface was recently shown to accelerate the rate of complex-formation between PN-1 and thrombin. The present paper demonstrates that the accelerative activity is primarily due to cell-surface heparan sulphate, with a much smaller contribution from chondroitin sulphate. This conclusion is supported by the effects of purified glycosaminoglycans on the second-order rate constant for the inhibition of thrombin by PN-1. Also, treatment of 35SO4(2-)-labelled cells with heparitin sulphate lyase or chondroitin sulphate ABC lyase demonstrated two discrete pools of 35S-labelled glycosaminoglycans; subsequent treatment of plasma membranes with these glycosidases showed that heparitin sulphate lyase treatment abolished about 80% of the accelerative activity and chondroitin sulphate ABC lyase removed the remaining 20%. These results show that two components are responsible for the acceleration of PN-1-thrombin complex-formation by human fibroblasts. Although dermatan sulphate is also present on fibroblasts, it did not accelerate the inhibition of thrombin by PN-1.


1983 ◽  
Vol 215 (1) ◽  
pp. 107-116 ◽  
Author(s):  
J T Gallagher ◽  
N Gasiunas ◽  
S L Schor

Human skin fibroblasts cultured on collagen gels produced two dermatan sulphate species, one, enriched in iduronic acid residues, that bound specifically to the collagenous fibres of the gel, the other, enriched in glucuronic acid, that accumulated in the culture medium. Collagen-binding and collagen-non-binding dermatan sulphates were also produced by cells grown on plastic surfaces, but in these cultures each constituent was released into the growth medium. Net synthesis of dermatan sulphate was 3-fold higher in cells maintained on collagen gels. In contrast, heparan sulphate synthesis was not influenced by the nature of the culture surface. The concentration of heparan sulphate in surface-membrane extracts was similar for cells grown on plastic and on collagen gels, but cells cultured on collagen showed a notable increase in the content of surface-membrane dermatan sulphate. The patterns of synthesis and distribution of sulphated glycosaminoglycans observed in skin fibroblasts maintained on collagen gels may reflect differentiated cellular functions.


1982 ◽  
Vol 201 (1) ◽  
pp. 233-240 ◽  
Author(s):  
Lars-Ȧke Fransson ◽  
Birgitta Havsmark ◽  
Vincenzo P. Chiarugi

1. Heparan sulphates from normal 3T3 fibroblasts are association-prone as indicated by their affinity for agarose gels substituted with cognate heparan sulphate species. Heparan sulphates from SV40-transformed or polyoma-virus-transformed cells have no affinity for the same gels. 2. Heparan sulphates from the medium, the pericellular and intracellular pools of normal, SV40-transformed and polyoma-transformed 3T3 cells were separated into four subfractions (HS1–HS4) by ion-exchange chromatography. In general, HS1–HS3 were found in cell-derived heparan sulphates, whereas HS3–HS4 were present in the medium. The heparan sulphates from transformed cells were more heterogeneous and of lower charge density than those from the normal counterpart. 3. Degradations via periodate oxidation/alkaline elimination yielded the oligomers glucosamine-(hexuronate–glucosamine)n-R with n=1–5 and a large proportion of N-sulphate groups. There was a large contribution of fragments n=4–5 from heparan sulphates of normal cells. These fragments were less common in low-sulphated heparan sulphates of transformed cells. In the case of medium-drived heparan sulphates all species had a low content of fragments n=4–5. 4. The size distribution of (glucuronate–N-acetylglucosamine)n regions was assessed after deaminative cleavage. It was broad and ranged from n=1–10 for all heparan sulphate species. In the case of medium-derived heparan sulphates there were distinct differences between normal and transformed cells. In the latter chains the N-acetyl-rich segments were both shorter and longer than in the normal case. The shape of the disaccharide peak was consistent with a lower content of O-sulphate in the heparan sulphates from transformed cells. 5. It was concluded that heparan sulphates from medium or transformed cells exhibit the greatest structural deviation from the normal case. The finding of lower proportions of extended, iduronate/glucuronate-bearing, N-sulphate-rich segments in heparan sulphates of transformed cells was particularly interesting in view of the fact that these elements have been associated with ability to self-interact.


2003 ◽  
Vol 372 (2) ◽  
pp. 371-380 ◽  
Author(s):  
Emanuel SMEDS ◽  
Hiroko HABUCHI ◽  
Anh-Tri DO ◽  
Eva HJERTSON ◽  
Helena GRUNDBERG ◽  
...  

Glycosaminoglycan heparan sulphate interacts with a variety of proteins, such as growth factors, cytokines, enzymes and inhibitors and, thus, influences cellular functions, including adhesion, motility, differentiation and morphogenesis. The interactions generally involve saccharide domains in heparan sulphate chains, with precisely located O-sulphate groups. The 6-O-sulphate groups on glucosamine units, supposed to be involved in various interactions of functional importance, occur in different structural contexts. Three isoforms of the glucosaminyl 6-O-sulphotransferase (6-OST) have been cloned and characterized [H. Habuchi, M. Tanaka, O. Habuchi, K. Yoshida, H. Suzuki, K. Ban and K. Kimata (2000) J. Biol. Chem. 275, 2859–2868]. We have studied the substrate specificities of the recombinant enzymes using various O-desulphated poly- and oligo-saccharides as substrates, and using adenosine 3′-phosphate 5′-phospho[35S]sulphate as sulphate donor. All three enzymes catalyse 6-O-sulphation of both -GlcA-GlcNS- and -IdoA-GlcNS- (where GlcA represents d-glucuronic acid, NS the N-sulphate group and IdoA the l-iduronic acid) sequences, with preference for IdoA-containing targets, with or without 2-O-sulphate substituents. 6-OST1 showed relatively higher activity towards target sequences lacking 2-O-sulphate, e.g. the -GlcA-GlcNS- disaccharide unit. Sulphation of such non-O-sulphated acceptor sequences was generally favoured at low acceptor polysaccharide concentrations. Experiments using partially O-desulphated antithrombin-binding oligosaccharide as the acceptor revealed 6-O-sulphation of N-acetylated as well as 3-O-sulphated glucosamine residues with each of the three 6-OSTs. We conclude that the three 6-OSTs have qualitatively similar substrate specificities, with minor differences in target preference.


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