Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Proteoglycans”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1996

Proteoglycan synthesis in human and murine haematopoietic progenitor cell lines: isolation and characterization of a heparan sulphate proteoglycan as a major proteoglycan from the human haematopoietic cell line TF-1.

Proteoglycans of bone-marrow stromal cells and their extracellular matrix are important components of the microenvironment of haematopoietic tissues. Proteoglycans might also be involved in the interaction of haematopoietic stem and stromal cells. Recently, several studies have been reported on the proteoglycan synthesis of stromal cells, but little is known about the proteoglycan synthesis of haematopoietic stem or progenitor cells. Here we report on the isolation and characterization of proteoglycans from two haematopoietic progenitor cell lines, the murine FDCP-Mix A4 and the human TF-1 cell line. Proteoglycans were isolated from metabolically labelled cells and purified by several chromatographic steps, including anion-exchange and size-exclusion chromatography. Biochemical characterization was performed by electrophoresis or gel-filtration chromatography before and after digestion with glycosaminoglycan-specific enzymes or HNO2 treatment. Whereas FDCP-Mix A4 cells synthesize a homogeneous chondroitin 4-sulphate proteoglycan, isolation and characterization of proteoglycans from the human cell line TF-1 revealed, that TF-1 cells synthesize, in addition to a chondroitin sulphate proteoglycan, a heparan sulphate proteoglycan as major proteoglycan. For this heparan sulphate proteoglycan a core protein size of approx. 59 kDa was determined. Immunochemical analysis of this heparan sulphate proteoglycan revealed that it is not related to the syndecan family nor to glypican.

Animals↗
PubMed1991

Characterization of heparan sulfate proteoglycan from calf lens capsule and proteoglycans synthesized by cultured lens epithelial cells. Comparison with other basement membrane proteoglycans.

After extraction with 4 M guanidinium chloride and purification by DEAE-cellulose chromatography, the heparan sulfate proteoglycan (HSPG) of calf anterior lens capsule was found to consist of two immunologically related components (Mr = 340,000 and 250,000) which upon deglycosylation with trifluoromethanesulfonic acid yielded core proteins with Mr values of 170,000 and 145,000. The heparan sulfate chains were uniform in size (Mr = 14,000) and manifested a clustering of sulfate groups in a peripheral domain. From the decrease in Mr observed after heparitinase digestion, it could be estimated that 6 and 11 glycosaminoglycan chains were present in the Mr = 250,000 and 340,000 components respectively. The occurrence of N-linked oligosaccharides was evident from the size difference of the heparitinase- and trifluoromethane-sulfonic acid-treated proteoglycans (approximately 20 kDa), as well as from the presence of a substantial number of mannose residues; furthermore, interaction of the capsule proteoglycan with Bandeiraea simplicifolia I suggested that these carbohydrate units contains terminal alpha-D-Gal groups. Cultured lens epithelial cells deposited a single [35S]sulfate-labeled proteoglycan into their matrix (Mr = 400,000) which was immunologically related to the lens capsule proteoglycan and contained only heparan sulfate chains. In addition to this component, the medium from these cells contained an immunologically unrelated HSPG (Mr = 150,000) as well as a chondroitin sulfate proteoglycan (Mr = 240,000). Examination of bovine glomeruli indicated that, in addition to the previously described 200-kDa HSPG, an immunologically related 350-kDa component was also present. This size heterogeneity, which is comparable to that seen in the lens capsule, is most readily attributable to proteolytic processing of a precursor molecule. Studies with polyclonal antibodies demonstrated only limited cross-reactivities between the Engelbreth-Holms-Swarm proteoglycan and the components from lens capsule and glomerular basement membrane; since even the latter two differed somewhat in their antigenic sites, it would appear that cell- and species-dictated genetic differences as well as post-translational events contribute to the diversity observed in basement membrane HSPGs.

Amino Acids↗
PubMed1984

The effect of link protein on proteoglycan aggregate structure. An electron microscopic study of the molecular architecture and dimensions of proteoglycan aggregates reassembled from the proteoglycan monomers and link proteins of bovine fetal epiphyseal cartilage.

Proteoglycan monomer and link protein were prepared from bovine fetal epiphyseal cartilage. Proteoglycan aggregates were reassembled from proteoglycan monomers and hyaluronic acid in the presence or in the absence of link protein at pH 7 and at pH 5. The proteoglycan solutions were spread on nitrocellulose films and examined by electron microscopy. At pH 7, the aggregates formed in the presence of link protein showed dramatic differences in their dimensions, compared with the link protein-free aggregates. The link protein-containing aggregates were five times longer and contained three times as many monomers per aggregates. The mean distance between monomers was twice as long and the spacing between monomers was more regular in the link protein-containing aggregates. Essentially the same differences between link protein-free and link protein-containing proteoglycan aggregates were observed at pH 5. These results show that link protein increases proteoglycan aggregate size by facilitating the binding of more monomers to hyaluronic acid and influences the spacing of monomers along hyaluronic acid chains.

Animals↗
PubMed2004

Proteoglycans in human laryngeal cartilage. Identification of proteoglycan types in successive cartilage extracts with particular reference to aggregating proteoglycans.

The content, composition and structure of proteoglycans (PGs) in adult human laryngeal cartilage (HLC) were investigated. PGs were extracted from the tissue by using two different extraction protocols. In the first protocol, PGs were extracted under dissociative conditions, 4 M guanidine HCl (GdnHCl), and in the second protocol, sequentially, with phosphate buffered saline (PBS) and solutions of increasing GdnHCl concentration (0.5, 1, 2 and 4 M). Chemical and immunological analyses of dissociate extracts (first protocol) revealed the presence of four, at least, different types of PGs. Aggrecan was the major PG, versican, decorin and biglycan being in small amounts. Galactosaminoglycan-containing PGs (GalAGPGs) represented the vast majority of total PGs present in extracts of HLC. Differential digestion with chondroitinase ABC and AC II showed that the GalAGPGs from HLC contained a significant proportion of dermatan sulphate (DS). In addition, disaccharide analysis showed that 6-sulphated disaccharides predominated in chondroitin sulphate (CS) chains. The sequential extraction (second protocol) indicated that PBS extract contained very little amount of PGs. The 0.5, 1 and 2 M GdnHCl extracts contained 6.3%, 24.5% and 15.2% of total extracted PGs, respectively. Four molar GdnHCl extracted the larger proportion, about 53%, of total PGs. This extract contained almost only proteoglycan aggregate components i.e., G1 bearing aggrecan, hyaluronan and link protein. The characterization of the aggrecan showed that it constituted a polydisperse population of monomers with an average molecular mass of 720 kDa. The glycosaminoglycans (GAGs) present were chondroitin sulphate with a M(r) of 15 kDa, and keratan sulphate (KS) with a M(r) of 10 kDa, in proportions 84% and 16%, respectively.

Adult↗
PubMed1990

Cartilage proteoglycan-induced arthritis in BALB/c mice. Antibodies that recognize human and mouse cartilage proteoglycan and can cause depletion of cartilage proteoglycan with little or no synovitis.

Human fetal cartilage proteoglycan (PG) induces the development of an erosive polyarthritis and spondylitis in BALB/c mice. We have examined the properties of 3 monoclonal antibodies (MAb) to human fetal cartilage PG isolated from immunized mice that cross-react with mouse cartilage PG. Compared with sera from arthritic mice, which contain antibodies reactive with keratan sulfate, MAb 202 (IgG1) reacted only with a protein-related epitope that is distributed on both hyaluronic acid-binding and chondroitin sulfate-attachment regions. MAb 813 (IgG1) reacted with the same fragments and recognized an epitope with the immunologic characteristics of keratan sulfate. MAb 945 (IgM) remains to be further characterized. Introduction of hybridomas secreting MAb 202 and MAb 945 into irradiated mice resulted in the loss of PG from articular cartilage and from growth plate cartilage (with MAb 202 only), as revealed by a loss of staining with toluidine blue. There was no synovial hyperplasia with MAb 202, but some hyperplasia and mononuclear cell infiltration was seen with MAb 945. This was accompanied by the binding of immunoglobulins to articular cartilage, as demonstrated by immunofluorescence. The hybridoma secreting MAb 813 produced no cartilage changes or synovitis, and there was no immunoglobulin binding to cartilage. Polymorphonuclear leukocyte infiltration was never observed with these antibodies. These studies indicate that MAb reactive with mouse cartilage PG can cause the depletion of PG from hyaline cartilage by mechanisms that may be both complement dependent and complement independent. Antibodies may serve to release and expose PG antigen to immune cells, as well as causing a loss of the mechanical properties of cartilage that are PG dependent.

Animals↗
PubMed1988

Proteoglycans of the human intervertebral disc. Electrophoretic heterogeneity of the aggregating proteoglycans of the nucleus pulposus.

Nuclei pulposi were dissected from lumbar discs of radiologically normal human spines of cadavers aged 17, 20 and 21 years. Proteoglycans were extracted with 4 M guanidine hydrochloride (dissociative conditions) with proteinase inhibitors and isolated as A1 fractions by associative density-gradient centrifugation. Aggregating and non-aggregating proteoglycans were separated by Sepharose 2B chromatography. Both aggregating and non-aggregating proteoglycans contained a keratan sulphate-rich region as isolated by chondroitinase/trypsin/chymotrypsin digestion and Sepharose CL-6B chromatography. Agarose/acrylamide-gel electrophoresis of individual fractions of a Bio-Gel A-50m dissociative-column separation of the aggregating proteoglycans revealed two, well-separated bands: S and F, the slower and faster migrating bands respectively. The non-aggregating proteoglycan fractions were eluted under associative conditions (0.5 M-sodium acetate, pH 6.8) and migrated as a single band in the electrophoretic system. The gel-electrophoretic heterogeneity of the aggregating proteoglycans was still evident after hydroxylamine fragmentation and removal of the hyaluronate-binding portion of the molecule. Dissociative density-gradient centrifugation of the aggregating proteoglycans partially separated the Band-S proteoglycans from the Band-F population. Subsequent dissociative chromatography of the high-buoyant-density Band F proteoglycans permitted discrimination of this band into two gel-electrophoresis-distinguishable populations (Bands F-1 and F-2). Enzyme-linked immunosorbent assays with a monoclonal antibody that recognized keratan sulphate demonstrated that the D1 fraction containing the Band F-1 proteoglycans was enriched in keratan sulphate compared with the total aggregating or non-aggregating pool of proteoglycans. The proteoglycans of young adult nucleus pulposus could then be ascribed to one of four structurally and/or electrophoretically distinct populations: (1) the non-aggregating population, which comprised about 70% of the total extractable proteoglycans; (2) the aggregating pool, comprising: (a) Band F-1 proteoglycans, which had a relatively large hydrodynamic size, uronate/protein weight ratio, were enriched in keratan sulphate and had a high buoyant density; (b) Band S proteoglycans, which migrated slower in agarose/acrylamide gels, had a smaller hydrodynamic size, lower buoyant density and a lower uronate/protein ratio than the Band F-1 population; (c) Band F-2 proteoglycans, which were lower in buoyant density, smaller in hydrodynamic size and slightly faster in electrophoretic mobility than the Band F-1 proteoglycans.

Adolescent↗
PubMedDate not supplied

Metabolism and turnover of cell surface-associated heparan sulfate proteoglycan and chondroitin sulfate proteoglycan in normal and cholesterol-enriched macrophages.

Analysis of sulfur-35-labeled proteoglycans indicated that cholesterol-enriched pigeon peritoneal macrophages synthesized 42% more 35S-labeled proteoglycan when compared with control macrophages during a 24-hour incubation. Proteoglycan turnover was subsequently studied in radiolabeled macrophage cultures after a 1-, 3-, 6-, 12-, or 24-hour chase with fresh media. During the chase, intracellular proteoglycan disappeared rapidly, whereas there was a small accumulation of 35S-labeled proteoglycan in the media that plateaued at about 6 hours and remained relatively constant thereafter. Pericellular heparan sulfate proteoglycan and chondroitin sulfate proteoglycan disappeared throughout the chase and did not appear to accumulate in the media or in the intracellular compartment. The rapid disappearance of intracellular proteoglycans along with the relative lack in metabolism of media proteoglycans indicated that the majority of pericellular proteoglycans were metabolized via an intracellular degradative pathway. Kinetic analysis of pericellular proteoglycans revealed the presence of a single pool of heparan sulfate proteoglycan (half-life [t1/2] = 6.9 hours) and a single pool of chondroitin sulfate proteoglycan (t1/2 = 11.5 hours) in control macrophage cultures. Cholesterol-enriched macrophage cultures also contained a single pool of pericellular heparan sulfate proteoglycan (t1/2 = 7.3 hours) but contained two pools of chondroitin sulfate proteoglycan (t1/2 = 0.8 hour and 25.9 hours).

Animals↗
PubMed1992

Chondroitin sulfate proteoglycan and heparan sulfate proteoglycan production by cultured pigeon peritoneal macrophages.

Proteoglycan production was examined in cultures of thioglycollate-elicited peritoneal macrophages obtained from White Carneau and Show Racer pigeons. Following a 24-h incubation in the presence of [35S]sulfate and [3H]serine, total production and distribution of 35S-labeled proteoglycan into media (60-65%), pericellular (21-27%), and intracellular (13-14%) compartments was similar in White Carneau and Show Racer macrophage cultures. Media proteoglycans consisted of high-molecular-weight chondroitin sulfate proteoglycan, low-molecular-weight chondroitin sulfate proteoglycan, and heparan sulfate proteoglycan. High-molecular-weight chondroitin sulfate proteoglycan was predominantly 6-sulfated (80%) and contained a core protein larger than 200 kd, whereas low-molecular-weight chondroitin sulfate proteoglycan was 4-sulfated and contained a 28-kd core protein. Pericellular proteoglycan was similar in size to low-molecular-weight proteoglycan and consisted of a predominantly 6-sulfated (75%) chondroitin sulfate proteoglycan and heparan sulfate proteoglycan. Intracellular 35S-labeled chondroitin sulfate and heparan sulfate were smaller than media and pericellular proteoglycans, suggestive of intracellular degradative processing.

Animals↗
PubMed1990

Inventory of human skin fibroblast proteoglycans. Identification of multiple heparan and chondroitin/dermatan sulphate proteoglycans.

Heparan sulphate and chondroitin/dermatan sulphate proteoglycans of human skin fibroblasts were isolated and separated after metabolic labelling for 48 h with 35SO4(2-) and/or [3H]leucine. The proteoglycans were obtained from the culture medium, from a detergent extract of the cells and from the remaining 'matrix', and purified by using density-gradient centrifugation, gel and ion-exchange chromatography. The core proteins of the various proteoglycans were identified by electrophoresis in SDS after enzymic removal of the glycosaminoglycan side chains. Skin fibroblasts produce a number of heparan sulphate proteoglycans, with core proteins of apparent molecular masses 350, 250, 130, 90, 70, 45 and possibly 35 kDa. The major proteoglycan is that with the largest core, and it is principally located in the matrix. A novel proteoglycan with a 250 kDa core is almost entirely secreted or shed into the culture medium. Two exclusively cell-associated proteoglycans with 90 kDa core proteins, one with heparan sulphate and another novel one with chondroitin/dermatan sulphate, were also identified. The heparan sulphate proteoglycan with the 70 kDa core was found both in the cell layer and in the medium. In a previous study [Fransson, Carlstedt, Cöster & Malmström (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 5657-5661] it was suggested that skin fibroblasts produce a proteoglycan form of the transferrin receptor. However, the core protein of the major heparan sulphate proteoglycan now purified does not resemble this receptor, nor does it bind transferrin. The principal secreted proteoglycans are the previously described large chondroitin sulphate proteoglycan (PG-L) and the small dermatan sulphate proteoglycans (PG-S1 and PG-S2).

Chondroitin Sulfate Proteoglycans↗
PubMed1983

Heparan sulfate proteoglycans from mouse mammary epithelial cells. A putative membrane proteoglycan associates quantitatively with lipid vesicles.

Mouse mammary epithelial (NMuMG) cells produce both cellular and extracellular heparan sulfate-rich proteoglycans. A cellular proteoglycan, but no extracellular proteoglycans, associates quantitatively and vectorially with lipid vesicles, as assessed by column chromatography and centrifugation. This lipophilic cellular proteoglycan is extracted as an aggregate when cells are treated with 4 M guanidine HCl, but is extracted as a single component in the presence of detergent, suggesting that it aggregates with cellular lipid. An association with lipid is confirmed by intercalation of the proteoglycan into the bilayer of lipid vesicles. Formation of lipid vesicles in the presence of the proteoglycan causes the proteoglycan to have the chromatographic and sedimentation behavior of the vesicles while destruction of the vesicles with detergent nullifies this effect. The proteoglycan is intercalated nullifies this effect. The proteoglycan is intercalated into the vesicles with its glycosaminoglycan-containing domain exposed to the exterior since mild trypsin treatment quantitatively removes this portion of the proteoglycan from the vesicle. After cleavage from the vesicle, the released proteoglycan chromatographs with an apparent molecular size similar to that of the whole proteoglycan, but no longer aggregates with lipid. Thus, trypsin removes a lipophilic domain which is responsible for its interaction with lipid and presumably anchors the proteoglycan in cellular membranes.

Animals↗
PubMed1998

Identification of the principal proteoglycan-binding site in LDL. A single-point mutation in apo-B100 severely affects proteoglycan interaction without affecting LDL receptor binding.

The subendothelial retention of LDLs through their interaction with proteoglycans has been proposed to be a key process in the pathogenesis of atherosclerosis. In vitro studies have identified eight clusters of basic amino acids in delipidated apo-B100, the protein moiety of LDL, that bind the negatively charged proteoglycans. To determine which of these sites is functional on the surface of LDL particles, we analyzed the proteoglycan-binding activity of recombinant human LDL isolated from transgenic mice. Substitution of neutral amino acids for the basic amino acids residues in site B (residues 3359-3369) abolished both the receptor-binding and the proteoglycan-binding activities of the recombinant LDL. Chemical modification of the remaining basic residues caused only a marginal further reduction in proteoglycan binding, indicating that site B is the primary proteoglycan-binding site of LDL. Although site B was essential for normal receptor-binding and proteoglycan-binding activities, these activities could be separated in recombinant LDL containing single-point mutation. Recombinant LDL with a K3363E mutation, in which a glutamic acid had been inserted into the basic cluster RKR in site B, had normal receptor binding but interacted defectively with proteoglycans; in contrast, another mutant LDL, R3500Q, displayed defective receptor binding but interacted normally with proteoglycans. LDL with normal receptor-binding activity but with severely impaired proteoglycan binding will be a unique resource for analyzing the importance of LDL- proteoglycan interaction in atherogenesis. If the subendothelial retention of LDL by proteoglycans is the initial event in early atherosclerosis, then LDL with defective proteoglycan binding may have little or no atherogenic potential.

Amino Acid Substitution↗
PubMed1986

Glomerular proteoglycans in diabetes. Partial structural characterization and metabolism of de novo synthesized heparan-35SO4 and dermatan-35SO4 proteoglycans in streptozocin-induced diabetic rats.

The metabolism of glomerular proteoglycans was studied in an effort to understand the mechanisms leading to reduction of glomerular basement membrane (GBM) heparan sulfate (heparan-SO4) proteoglycan in diabetes. Glomeruli were isolated from control and streptozocin-induced diabetic rats after exposure to [35S]sulfate. A pool of rapidly metabolized 35S-glycosaminoglycans (GAG), predominantly heparan-35SO4, was present in GBMs from controls but not diabetics, whereas intact isolated glomeruli from the two groups contained similar quantities of 35S-macromolecules after 4 and 16 h in vitro. Glomeruli from diabetics contained less 35S-proteoglycan than controls after 16 h in vivo. A more rapid disappearance of [35S]sulfate from serum and an increased inorganic sulfate concentration in diabetes may account for this difference. Glomeruli from diabetics contained more heparan-35SO4 and less dermatan-35SO4 proteoglycan than control glomeruli in vitro. Diabetic glomerular heparan-35SO4 proteoglycan and its GAG chains had hydrodynamic sizes similar to controls (Mr, 13 and 1.25 X 10(4), respectively). A heparin-releasable heparan-35SO4 proteoglycan detected in isolated control glomeruli by gel electrophoresis was present in chase medium of glomeruli from diabetics in the absence of heparin. Two dermatan-35SO4 proteoglycans were synthesized in vitro. One had size and charge properties similar to glomerular heparan-35SO4 proteoglycan. A second, larger dermatan-35SO4 proteoglycan accumulated in tissue over 16 h. It was partially excluded from Sepharose CL-6B columns and eluted from Sepharose CL-4B columns at Kav = 0.32. The hydrodynamic sizes of both tissue forms of dermatan-35SO4 proteoglycans were similar in diabetics and controls. Differences in the biochemical characteristics of the major de novo synthesized glomerular proteoglycan pools could not be invoked to explain altered metabolism of GBM heparan sulfate in diabetic animals. These changes may result from diminished affinity of heparan sulfate proteoglycan for extracellular matrix or cell surfaces and may account for altered glomerular ultrafiltration properties in diabetes mellitus.

Animals↗
PubMed1989

Analysis of the proteoglycans synthesized by corneal explants from embryonic chicken. I. Characterization of the culture system with emphasis on stromal proteoglycan biosynthesis.

Corneal explants with scleral rims were freshly prepared from day 18 chicken embryos and incubated in vitro for 3 h in the presence of various radioactive precursors. Radiolabeled proteoglycans were isolated from the stromal tissue and culture medium for analysis. Two predominant proteoglycans were identified in corneal stroma. One contains dermatan sulfate and the other contains keratan sulfate; a structural analysis of each is reported in the accompanying paper (Midura, R.J., and Hascall, V.C. (1989) J. Biol. Chem. 264, 1423-1430). A minor keratan sulfate proteoglycan distinct from the major form, a small amount of heparan sulfate proteoglycan, and some sulfated glycoproteins were also detected in stromal extracts. The biosynthesis of the dermatan sulfate proteoglycan was stable in vitro and in ovo, whereas that of the major keratan sulfate proteoglycan was stable only in ovo. Various treatments were tried to maintain a high rate of keratan sulfate synthesis with time in culture. Cooling the corneal explants to 5 degrees C was the only treatment that reduced this decline in keratan sulfate synthesis in vitro to any significant extent. Three major proteoglycans were observed in the culture medium. Two were dermatan sulfate proteoglycan and appeared to be mainly derived from the scleral tissue surrounding the corneal explant. The third proteoglycan contained keratan sulfate. It was smaller in size and lower in charge density compared to the keratan sulfate proteoglycan found in the stroma, but both appeared to have similar core protein sizes. It seems likely that this proteoglycan was synthesized in the stroma and secreted into the medium. A small amount of heparan sulfate proteoglycan and some sulfated glycoproteins were also detected in the medium.

Animals↗
PubMed1984

Chondroitin/dermatan sulfate proteoglycan in human fetal membranes. Demonstration of an antigenically similar proteoglycan in fibroblasts.

A proteoglycan was isolated from fetal membranes which had been separated from human postpartum placenta. The glycosaminoglycan side chains (Mr = 55,000) were found to be composed of 75% chondroitin sulfate and 23% dermatan sulfate as determined by chondroitinase ABC or AC II digestion. NH2-terminal microsequencing of the intact proteoglycan revealed a single amino acid sequence of (sequence; see text) A rabbit antiserum raised against the intact proteoglycan reacted in sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting with Mr = 45,000 and 43,000 core polypeptides from chondroitinase-treated proteoglycan. Affinity-purified antibodies from this antiserum precipitated from human embryonic fibroblast culture fluid a proteoglycan which has an approximate Mr = 120,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This proteoglycan has on the average two polysaccharide side chains. As defined by chondroitinase digestion, these chains consist of 66% dermatan sulfate and 20% chondroitin sulfate. Digestion of the glycosaminoglycan with chondroitinase ABC converted the proteoglycan to a Mr = 45,000 major and a Mr = 43,000 minor core polypeptide. Tissue immunofluorescence localized the proteoglycan to interstitial matrices, suggesting that it is a product of mesenchymal cells. The methods we have devised for the purification of the fetal membrane proteoglycan in chemical amounts and the antibodies we have prepared against it will allow studies on the structural and functional properties of the proteoglycan and on the expression of immunologically cross-reactive proteoglycans by various cells and tissues.

Amino Acid Sequence↗
PubMed1999

Molecular self-recognition and adhesion via proteoglycan to proteoglycan interactions as a pathway to multicellularity: atomic force microscopy and color coded bead measurements in sponges.

During the emergence of multicellular organisms, molecular mechanisms evolved to allow maintenance of anatomical integrity and self-recognition. We propose that carbohydrates from proteoglycans, as the most peripheral cell surface, and matrix molecules might have provided these key adhesion and recognition functions. If so, the Porifera as the simplest metazoans alive today should retain, at least in part, proteoglycan adhesion and recognition mechanisms. Early work on cell adhesion of dissociated marine sponge cells provided important phenomenological evidence for cell sorting. Here is reviewed recent work on molecular mechanisms of cell recognition and adhesion mediated by cell surface proteoglycans purified from three marine sponge species, Microciona prolifera, Halichondria panicea, and Cliona celata. Biochemical characterization of isolated proteoglycans showed that each species expressed a unique type of primordial molecule named glyconectins. These proteoglycans displayed species-specific self-recognition and adhesion in color-coded bead, cell, and blotting assays. The specificity of homophilic proteoglycan to proteoglycan interactions in the Porifera approaches the binding selectivity of the evolutionarily advanced immunoglobulin superfamily system. Such xeno-selectivity may be a new paradigm for the molecular self-recognition, which was a fundamental requirement in the self/non-self discrimination during the emergence of multicellularity and further divergence of species. We have used atomic force microscopy (AFM) technology to directly measure intermolecular binding strength between individual pairs of ligand and receptor molecules in physiological solution. Homophilic glyconectin interactions were investigated by AFM after covalent attachment of the protein core to the sensor tip and to a flat surface, leaving the carbohydrates unmodified. AFM measurements of the binding strength between glyconectins indicated that one pair of molecules could theoretically hold the weight of 1,600 cells in physiological solution. These results provided the first essential and quantitative evidence that proteoglycan-proteoglycan binding can perform the adhesion function that we have assigned to it. Our investigations with purified proteoglycans from the marine sponge M. prolifera (glyconectin 1) using bead and cell adhesion assays have provided evidence that a new molecular mechanism of polyvalent and specific glycan-glycan binding between proteoglycans can mediate cell recognition and adhesion. Partial sequencing of the glycans has revealed two new cell adhesion carbohydrate structures: (3)GlcNAc(3OSO3)beta1-3Fuc and Pyr4,6Galbeta1-4GlcNAcbeta1-3Fuc.

Animals↗
PubMed2004

Immunocytochemistry of keratan sulfate proteoglycan and dermatan sulfate proteoglycan in porcine tooth-germ dentin.

Keratan sulfate proteoglycan and dermatan sulfate proteoglycan have been reported to inhibit collagen fibrillogenesis. We investigated their distribution in order to evaluate the role of proteoglycan in dentinogenesis. Specimens of porcine tooth-germ dentin and erupted teeth were the materials on which antibodies to keratin sulfate and dermatan sulfate proteoglycan were used. Predentin was found to be positive for both antibodies and the reaction ceased in the calcification front. Uniformly thick collagen fibrils (30-70 nm in diameter) were distributed in the predentin matrix, which would become intertubular dentin in the future. Both antibodies reacted positively along these fibrils. In contrast, along the surface layer of dentin in the tooth germ and that in erupted teeth, collagen fibrils of 10-300 nm in diameter were noted occasionally in dentinal tubules whose odontoblastic processes had disappeared and these heterogeneous fibrils were negative for both antibodies. Our findings suggest that keratan sulfate proteoglycan and dermatan sulfate proteoglycan distributed in the predentin inhibit calcification of collagen fibrils in the uncalcified matrix and disappear in the calcification front. It is further suggested that keratan sulfate proteoglycan and dermatan sulfate proteoglycan distributed along collagen fibrils in the predentin matrix maintain uniform thickness, whereas collagen fibrils in dentinal tubules varied in thickness because of the absence of involvement of both proteoglycans. Therefore, keratan sulfate proteoglycan and dermatan sulfate proteoglycan were thought to be involved in both calcification and matrix formation.

Animals↗
PubMed1986

Complexes of heparin proteoglycans, chondroitin sulfate E proteoglycans, and [3H]diisopropyl fluorophosphate-binding proteins are exocytosed from activated mouse bone marrow-derived mast cells.

The predominant [3H]diisopropyl fluorophosphate (DFP)-binding proteins that are released from the secretory granules of activated mouse bone marrow-derived mast cells (BMMC) are demonstrated to have an isoelectric point of approximately 9.1 and to be complexed to proteoglycans. Upon Sepharose CL-2B chromatography of the supernatants of calcium ionophore-activated BMMC, 67-78% of the total exocytosed [3H]DFP-binding proteins co-eluted in the excluded volume of the column as a greater than 1 X 10(7) Mr complex bound to 4-7% of the total exocytosed proteoglycans. The remainder of the exocytosed proteoglycans, which filtered in the included volume of the gel filtration column with a Kav of 0.66, contained chondroitin sulfate E glycosaminoglycans. After dissociation of the large Mr complexes of [3H]DFP-binding proteins-proteoglycans with 5 M NaCl and removal of the proteins via phenyl-Sepharose chromatography, the proteoglycans filtered from the Sepharose CL-2B column as a single peak with a Kav of 0.66. The susceptibility of 24-59% and 36-76% of the glycosaminoglycans in the large Mr complex to degradation by nitrous acid and chondroitinase ABC, respectively, indicated the presence of proteoglycans that contained heparin and chondroitin sulfate glycosaminoglycans. Disaccharide analysis revealed that the chondroitin sulfate in the high Mr complex was chondroitin sulfate E. Following chondroitinase ABC treatment of the large Mr complex, the residual heparin proteoglycans filtered on Sepharose CL-4B under dissociative conditions with the same Kav as the original, untreated proteoglycans. Thus, the protein-proteoglycan complexes that are exocytosed from activated mouse BMMC contain approximately equal amounts of proteoglycans of comparable size that bear either predominantly heparin or predominantly chondroitin sulfate E glycosaminoglycans. The demonstration of these secreted complexes indicates that the intragranular protease-resistant heparin and chondroitin sulfate E proteoglycans in the T cell factor-dependent BMMC bind serine proteases throughout the activation-secretion response.

Animals↗
PubMed1993

Independent effects of interleukin 1 on proteoglycan synthesis and proteoglycan breakdown of bovine articular cartilage in vitro.

We studied the effects of human recombinant interleukin-1 beta on proteoglycan metabolism of bovine articular cartilage in organ culture. IL-1 was more potent in inhibiting synthesis (IC50 4 ng/mL) than in stimulating breakdown of proteoglycans (EC50 200 ng/mL). Inhibition of proteoglycan synthesis began to plateau earlier (2 days) than stimulation of proteoglycan release (4 days). Both effects could be neutralized with a polyclonal anti-IL-1 beta antibody; however, higher antibody titers were required to block IL-1 effects on proteoglycan synthesis than to neutralize those on proteoglycan release. Chloroquine, but not hydrocortisone, blocked IL-1-mediated proteoglycan breakdown. Both drugs, however, augmented IL-1-induced inhibition of proteoglycan synthesis. Our data suggest that the effects of IL-1 on articular cartilage proteoglycan synthesis and proteoglycan breakdown can be regulated independently.

Animals↗