Isolation of proteoglycans from human articular cartilage.
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ABSTRACT:
SUBMITTER: Bayliss MT
PROVIDER: S-EPMC1184201 | biostudies-other | 1978 Jan
REPOSITORIES: biostudies-other
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Project description:Full-depth plugs of adult human articular cartilage were cut into serial slices from the articular surface and analysed for their glycosaminoglycan content. The amount of chondroitin sulphate was highest in the mid-zone, whereas keratan sulphate increased progressively through the depth. Proteoglycans were isolated from each layer by extraction with 4M-guanidinium chloride followed by centrifugation in 0.4M-guanidinium chloride/CsCl at a starting density of 1.5 g/ml. The efficiency with which proteoglycans were extracted depended on slice thickness, and extraction was complete only when cartilage from each zone was sectioned at 20 microns or less. When thick sections (250 microns) were extracted, hyaluronic acid was retained in the tissue. Most of the proteoglycans, extracted from each layer under optimum conditions, could interact with hyaluronic acid to form aggregates, although the extent of aggregation was less in the deeper layers. Two pools of proteoglycan were identified in all layers by gel chromatography (Kav. 0.33 and 0.58). The smaller of these was rich in keratan sulphate and protein, and gradually increased in proportion through the cartilage depth. Chondroitin sulphate chain size was constant in all regions. The changes in composition and structure observed were consistent with the current model for hyaline-cartilage proteoglycans and were similar to those observed with increasing age in human articular cartilage.
| S-EPMC1154105 | biostudies-other
Project description:The composition of macroscopically normal hip articular cartilage obtained from dogs of various ages was studied. Pieces of cartilage with signs of degeneration were studied separately. In normal aging, the extraction yield of proteoglycans decreased; the keratan sulphate content of extracted proteoglycans increased and the chondroitin sulphate content decreased. The extracted proteoglycans were smaller in the older cartilage, mainly owing to a decrease in the chondroitin sulphate-rich region of the proteoglycan monomers. The hyaluronic acid-binding region and the keratan sulphaterich region were increased and the molar concentration of proteoglycan probably increase with increasing age. The degenerated cartilage had higher water content and the proteoglycans, as well as other tissue components, gave higher yields. The proteoglycan monomers from the degenerated cartilage were smaller than those from normal cartilage of the same age, and hence had a smaller chondroitin sulphate-rich region and some of the molecules also appeared to lack the hyaluronic acid-binding region. Increased proteolytic activity may be involved in the process of cartilage degeneration.
| S-EPMC1184203 | biostudies-other
Project description:Approx. 10% of the total proteoglycan content of normal young human articular cartilage was extracted under associative conditions with Dulbecco's PBS. Proteoglycans isolated from the extract by Q-Sepharose chromatography were separated by gel chromatography and characterized by gradient gel SDS/PAGE and immunoblotting. Three species of small proteoglycans, two main populations of aggrecan and a population of its smaller fragments were identified. The major populations of aggrecan contained chondroitin sulphate chains, all or part of the N-terminal G1 and G2 domains and, therefore, intact keratan sulphate domains. The larger population was estimated by gradient SDS/PAGE to have a molecular mass of approx. 600 kDa or greater. The second population had an apparent molecular mass of approx. 300-600 kDa. Core proteins derived from these populations of proteoglycans separated on SDS/PAGE into several clusters of bands in the range from 120 to approx. 360 kDa. The extract further contained smaller fragments which lacked chondroitin sulphate but reacted with antibodies against keratan sulphate, and against epitopes present in the G2 domain of aggrecan. The presence of the G2 domain in a broad range of populations of decreasing size indicated extensive cleavage of the aggrecan core protein within its chondroitin sulphate domain. These findings suggest that fragmentation of aggrecan probably occurs in vivo in normal articular cartilage of young individuals. Associative extracts also contained decorin, biglycan and fibromodulin. These were resolved from aggrecan by gel chromatography and identified by immunodetection.
| S-EPMC1134335 | biostudies-other
Project description:Dermatan sulphate proteoglycans were purified from juvenile human articular cartilage, with a yield of about 2 mg/g wet wt. of cartilage. Both dermatan sulphate proteoglycan I (DS-PGI) and dermatan sulphate proteoglycan II (DS-PGII) were identified and the former was present in greater abundance. The two proteoglycans could not be resolved by agarose/polyacrylamide-gel electrophoresis, but could be resolved by SDS/polyacrylamide-gel electrophoresis, which indicated average Mr values of 200,000 and 98,000 for DS-PGI and DS-PGII respectively. After digestion with chondroitin ABC lyase the Mr values of the core proteins were 44,000 for DS-PGI and 43,000 and 47,000 for DS-PGII, with the smaller core protein being predominant in DS-PGII. Sequence analysis of the N-terminal 20 amino acid residues reveals the presence of a single site for the potential substitution of dermatan sulphate at residue 4 of DS-PGII and two such sites at residues 5 and 10 for DS-PGI.
| S-EPMC1133347 | biostudies-other
Project description:Monoclonal antibodies were prepared that recognize different age-related epitopes on proteoglycan subunits of high buoyant density isolated from human epiphysial and articular cartilages. Antibody EFG-4 (IgG1) recognizes a proteinase-sensitive segment associated with the core protein. Antibody BCD-4 (IgG1) reacts with keratan sulphate bound to core protein. Both epitopes are minimally expressed in foetal cartilage and increase with age after birth to become maximally expressed in adult cartilage by about 30 years of age. In contrast, monoclonal antibody alpha HFPG-846 (IgM) recognizes a core-protein-related epitope that is maximally expressed in young foetal cartilage, declines up to birth and thereafter and is almost absent after about 30 years of age. Antibody alpha HFPG-846 was used to isolate by immuno-affinity chromatography two subpopulations of proteoglycan subunits from a 16-year-old-human cartilage proteoglycan subunit preparation. Only the antibody-unbound population showed a significant reaction with antibodies EGF-4 and BCD-4. The amino acid and carbohydrate compositions of these proteoglycan fractions were different, and one (antibody-bound) resembled those of foetal and the other (antibody-unbound) resembled those of adult proteoglycans isolated from 24-27-week-old-foetal and 52-56-year-old-adult cartilage respectively. These observations demonstrate that human cartilages contain at least two chemically and immunochemically distinct populations of proteoglycans, the proportions and content of which are age-dependent. It is likely that these populations represent the products of different genes, though their heterogeneity may be compounded by the result of different post-translation modifications.
| S-EPMC1146787 | biostudies-other
Project description:Monoclonal antibodies produced against chondroitinase-treated human adult cartilage proteoglycans were selected for their ability to recognize epitopes on native proteoglycans. Binding analyses revealed that four of these monoclonal antibodies (BCD-4, BCD-7, EFG-4 and KPC-190) each recognized a different epitope on the same proteoglycan molecule which represents a subpopulation of a high buoyant density (D1) fraction of human articular cartilage proteoglycans (10, 30, 50 and 60% in fetal-newborn, 1.5 years old, 15 years old and 52-56 years old cartilages, respectively). Analysis of epitope specificities revealed that BCD-7 and EFG-4 monoclonal antibodies recognized epitopes on proteoglycan monomer which are associated with the protein structure in that they are sensitive to cleavage by Pronase, papain and alkali treatment and do not include keratan sulphate, chondroitin sulphate or oligosaccharides. The BCD-4 and KPC-190 epitopes also proved to be sensitive to Pronase or papain digestion or to alkali treatment, but keratanase or endo-beta-galactosidase also reduced the immunoreactivity of these epitopes. These observations indicate that the BCD-4 and KPC-190 epitopes represent peptides substituted with keratan sulphate or keratan sulphate-like structures. The BCD-4 epitope is, however, absent from a keratan sulphate-rich fragment of human adult proteoglycan, while the other three epitopes were detected in this fragment. None of these four epitopes were detected in the link proteins of human cartilage, in the hyaluronic acid-binding region of human newborn cartilage proteoglycan, in Swarm rat chondrosarcoma proteoglycan, in chicken limb bud proteoglycan monomer and in the small dermatan sulphate-proteoglycan of bovine costal cartilage. EFG-4 and KPC-190 epitopes were not detected in human fetal cartilage proteoglycans, although fetal molecules contained trace amounts of epitopes reactive with BCD-4 and BCD-7 antibodies.
| S-EPMC1146523 | biostudies-other
Project description:This study presents direct experimental evidence for assessing the electrostatic and non-electrostatic contributions of proteoglycans to the compressive equilibrium modulus of bovine articular cartilage. Immature and mature bovine cartilage samples were tested in unconfined compression and their depth-dependent equilibrium compressive modulus was determined using strain measurements with digital image correlation analysis. The electrostatic contribution was assessed by testing samples in isotonic and hypertonic saline; the combined contribution was assessed by testing untreated and proteoglycan-depleted samples. Though it is well recognized that proteoglycans contribute significantly to the compressive stiffness of cartilage, results demonstrate that the combined electrostatic and non-electrostatic contributions may add up to more than 98% of the modulus, a magnitude not previously appreciated. Of this contribution, about two thirds arises from electrostatic effects. The compressive modulus of the proteoglycan-depleted cartilage matrix may be as low as 3kPa, representing less than 2% of the normal tissue modulus; experimental evidence also confirms that the collagen matrix in digested cartilage may buckle under compressive strains, resulting in crimping patterns. Thus, it is reasonable to model the collagen as a fibrillar matrix that can sustain only tension. This study also demonstrates that residual stresses in cartilage do not arise exclusively from proteoglycans, since cartilage remains curled relative to its in situ geometry even after proteoglycan depletion. These increased insights on the structure-function relationships of cartilage can lead to improved constitutive models and a better understanding of the response of cartilage to physiological loading conditions.
| S-EPMC2900255 | biostudies-literature
Project description:Proteoglycans (PGs), also known as a viscous lubricant, is the main component of the cartilage extracellular matrix (ECM). The loss of PGs is accompanied by the chronic degeneration of cartilage tissue, which is an irreversible degeneration process that eventually develops into osteoarthritis (OA). Unfortunately, there is still no substitute for PGs in clinical treatments. Herein, we propose a new PGs analogue. The Glycopolypeptide hydrogels in the experimental groups with different concentrations were prepared by Schiff base reaction (Gel-1, Gel-2, Gel-3, Gel-4, Gel-5 and Gel-6). They have good biocompatibility and adjustable enzyme-triggered degradability. The hydrogels have a loose and porous structure suitable for the proliferation, adhesion, and migration of chondrocytes, good anti-swelling, and reduce the reactive oxygen species (ROS) in chondrocytes. In vitro experiments confirmed that the glycopolypeptide hydrogels significantly promoted ECM deposition and up-regulated the expression of cartilage-specific genes, such as type-II collagen, aggrecan, and glycosaminoglycans (sGAG). In vivo, the New Zealand rabbit knee articular cartilage defect model was established and the hydrogels were implanted to repair it, the results showed good cartilage regeneration potential. It is worth noting that the Gel-3 group, with a pore size of 122 ± 12 μm, was particularly prominent in the above experiments, and provides a theoretical reference for the design of cartilage-tissue regeneration materials in the future. Graphical abstract Schematic diagram illustrating glycopolypeptide POD hydrogels to repair articular-cartilage defects.Image 1
| S-EPMC10205498 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2022-11-15 | GSE217871 | GEO
Project description:1. Analysis of the purified proteoglycans extracted from normal human articular cartilage with 4M-guanidinium chloride showed that there was an age-related increase in their content of protein and keratan sulphate. 2. The hydrodynamic size of the dissociated proteoglycans also decreased with advancing age, but there was little change in the proportion that could aggregate. 3. Results suggested that some extracts of aged-human cartilage had an increased content of hyaluronic acid compared with specimens from younger patients. 4. Dissociated proteoglycans, from cartilage of all age groups, bind to hyaluronic acid and form aggregates in direct proportion to the hyaluronic acid concentration. 5. Electrophoretic heterogeneity of the dissociated proteoglycans was demonstrated on polyacrylamide/agarose gels. The number of proteoglycan species observed was also dependent on the age of the patient.
| S-EPMC1186290 | biostudies-other