The alkaline cleavage and borohydride reduction of cartilage proteoglycan.
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ABSTRACT:
SUBMITTER: Robinson HC
PROVIDER: S-EPMC1177724 | biostudies-other | 1973 Jul
REPOSITORIES: biostudies-other
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Project description:BackgroundAlthough proteoglycan (PG) is one of the major components of cartilage matrices, its biological function is not fully elucidated.MethodsThe objectives of this study were to investigate the proliferation and differentiation of chondrocytes embedded in atelocollagen gel with exogenous cartilage PG (PG-atelocollagen gel) in vitro, and also to evaluate the repair of cartilage defects by PG-atelocollagen gel in vivo. In the in vitro study, rabbit chondrocytes were cultured in the PG-atelocollagen gel. Cell proliferation and mRNA expression levels were measured, and gels were histologically evaluated. In the in vivo study, cultured PG-atelocollagen gel containing chondrocytes were transplanted into full-thickness articular cartilage defects in rabbit knees, and evaluated macroscopically and histologically.ResultsFor the in vitro study, chondrocyte proliferation in 5.0 mg/ml PG-atelocollagen gel was enhanced, and the gene expression of Col2a1 and Aggrecan were decreased. In contrast, chondrocyte proliferation in 0.1 and 1.0 mg/ml PG-atelocollagen gel was not enhanced. The gene expression of Aggrecan in 0.1 and 1.0 mg/ml PG-atelocollagen gel was increased. For the in vivo study, the histological average total score of the 0.1 mg/ml PG-atelocollagen gel was significantly better than that of the group without PG.ConclusionsAlthough the appropriate concentration of PG has not been defined, this study suggests the efficacy of PG for cartilage repair.
| S-EPMC3311805 | biostudies-literature
Project description:The action of purified rabbit bone stromelysin was investigated on proteoglycan aggregates from pig laryngeal cartilage. The enzyme caused a rapid fall in viscosity of proteoglycan aggregate solution (6 mg/ml), and the products of a partial digest (60% loss of relative viscosity) and a complete digest (95% loss of relative viscosity) were characterized. Analysis by gel chromatography on Sepharose 2B under associative conditions showed that 95% of the glycosaminoglycans in the complete digest were in small-sized fragments, whereas most of the hyaluronan-binding G1 domain and link protein remained intact and bound to hyaluronan. In contrast, there was extensive digestion of the G2 domain which resulted in 76% loss in its detection by immunoassay. Analysis of the partial digest also showed considerable loss (40%) of detection of the G2 domain, but the glycosaminoglycan-rich fragments were much larger than in the complete digest. There was also much less cleavage to create small fragments containing the G1 domain. This was evident on SDS/PAGE analysis where a 58 kDa G1 domain fragment was abundant in the complete digest, but was only present in small amounts in the partial digest. There was also only very limited conversion of link protein from a 44 kDa form to a 40 kDa form. The digestion of proteoglycan aggregate (6 mg/ml) by stromelysin was unaffected by the addition of a high concentration of extra chondroitin sulphate chains (14 mg/ml), and the digestion of proteoglycan monomer showed that the G1 domain was resistant to stromelysin digestion even when not bound to hyaluronan and link protein. The results show that stromelysin degrades the proteoglycan protein core with major cleavages close to, but not within, the G1 domain, and extensive cleavage in other regions. Experiments with purified collagenase, a metalloproteinase structurally related to stromelysin, showed that it too cleaved proteoglycan at several sites within the glycosaminoglycan-rich region of the core protein. Metalloproteinase attack on proteoglycan thus not only occurs with stromelysin but also with collagenase.
| S-EPMC1151507 | biostudies-other
Project description:Purpose: One of the essential requirements in maintaining the normal joint motor function is the perfect tribological property of the articular cartilage. Many cartilage regeneration strategies have been developed for treatment in early stages of osteoarthritis, but there is little information on how repaired articular cartilage regains durability. The identification of biomarkers that can predict wear resistant property is critical to advancing the success of cartilage regeneration therapies. Proteoglycan 4 (PRG4) is a macromolecule distributing on the chondrocyte surface that contributes to lubrication. In this study, we investigate if PRG4 expression is associated with tribological properties of regenerated cartilage, and is able to predict its wear resistant status. Methods: Two different strategies including bone marrow enrichment plus microfracture (B/BME-MFX) and microfracture alone (B-MFX) of cartilage repair in sheep were used. PRG4 expression and a series of tribological parameters on regenerated cartilage were rigorously examined and compared. Results: Highly and continuously expression of PRG4 in regenerated cartilage surface was negatively correlated with each tribological parameter (P<0.0001, respectively). Multivariate analysis showed that PRG4 expression was the key predictor that contributed to the promotion of cartilage wear resistance. Conclusion: Higher PRG4 expression in regenerated cartilage is significantly associated with wear resistance improvement. PRG4 may be useful for predicting the wear resistant status of regenerated cartilage and determining the optimal cartilage repair strategy.
| S-EPMC7052906 | biostudies-literature
Project description:In this work, sodium borohydride was used as a strong reductant of traces of platinum complex ions. The investigations of the kinetics of redox reaction between platinum(IV) chloride complex ions and sodium borohydride were carried out. For the first time, the kinetic experiments were carried out in a basic medium (pH~13), which prevents NaBH4 from decomposition and suppresses the release of hydrogen to the environment. The rate constants of Pt(IV) reduction to Pt(II) ions under different temperatures and concentrations of chloride ions conditions were determined. In alkaline solution (pH~13), the values of enthalpy and entropy of activation are 29.6 kJ/mol and -131 J/mol K. It was also found that oxygen dissolved in the solution strongly affects kinetics of the reduction process. Using collected results, the reduction mechanism was suggested. For the first time, the appearance of diborane as an intermediate product during Pt(IV) ions reduction was suggested. Moreover, the influence of oxygen present in the reacting solution on the rate of reduction reaction was also shown.
| S-EPMC8201063 | biostudies-literature
Project description:BackgroundRheumatoid arthritis (RA) is an autoimmune disease of the synovial joints. The autoimmune character of RA is underscored by prominent production of autoantibodies such as those against IgG (rheumatoid factor), and a broad array of joint tissue-specific and other endogenous citrullinated proteins. Anti-citrullinated protein antibodies (ACPA) can be detected in the sera and synovial fluids of RA patients and ACPA seropositivity is one of the diagnostic criteria of RA. Studies have demonstrated that RA T cells respond to citrullinated peptides (epitopes) of proteoglycan (PG) aggrecan, which is one of the most abundant macromolecules of articular cartilage. However, it is not known if the PG molecule is citrullinated in vivo in human cartilage, and if so, whether citrulline-containing neoepitopes of PG (CitPG) can contribute to autoimmunity in RA.MethodsCitPG was detected in human cartilage extracts using ACPA+ RA sera in dot blot and Western blot. Citrullination status of in vitro citrullinated recombinant G1 domain of human PG (rhG1) was confirmed by antibody-based and chemical methods, and potential sites of citrullination in rhG1 were explored by molecular modeling. CitPG-specific serum autoantibodies were quantified by enzyme-linked immunosorbent assays, and CitPG was localized in osteoarthritic (OA) and RA cartilage using immunohistochemistry.FindingsSera from ACPA+ RA patients reacted with PG purified from normal human cartilage specimens. PG fragments (mainly those containing the G1 domain) from OA or RA cartilage extracts were recognized by ACPA+ sera but not by serum from ACPA- individuals. ACPA+ sera also reacted with in vitro citrullinated rhG1 and G3 domain-containing fragment(s) of PG. Molecular modeling suggested multiple sites of potential citrullination within the G1 domain. The immunohistochemical localization of CitPG was different in OA and RA cartilage.ConclusionsCitPG is a new member of citrullinated proteins identified in human joints. CitPG could be found in both normal and diseased cartilage specimens. Antibodies against CitPG may trigger or augment arthritis by forming immune complexes with this autoantigen in the joints of ACPA+ RA patients.
| S-EPMC4778950 | biostudies-literature
Project description:The first use of a dinuclear UIII/UIII complex in the activation of small molecules is reported. The octadentate Schiff-base pyrrole, anthracene-hinged 'Pacman' ligand LA combines two strongly reducing UIII centres and three borohydride ligands in [M(THF)4][{U(BH4)}2(?-BH4)(LA)(THF)2] 1-M, (M = Li, Na, K). The two borohydride ligands bound to uranium outside the macrocyclic cleft are readily substituted by aryloxide ligands, resulting in a single, weakly-bound, encapsulated endo group 1 metal borohydride bridging the two UIII centres in [{U(OAr)}2(?-MBH4)(LA)(THF)2] 2-M (OAr = OC6H2t Bu3-2,4,6, M = Na, K). X-ray crystallographic analysis shows that, for 2-K, in addition to the endo-BH4 ligand the potassium counter-cation is also incorporated into the cleft through ?5-interactions with the pyrrolides instead of extraneous donor solvent. As such, 2-K has a significantly higher solubility in non-polar solvents and a wider U-U separation compared to the 'ate' complex 1. The cooperative reducing capability of the two UIII centres now enforced by the large and relatively flexible macrocycle is compared for the two complexes, recognising that the borohydrides can provide additional reducing capability, and that the aryloxide-capped 2-K is constrained to reactions within the cleft. The reaction between 1-Na and S8 affords an insoluble, presumably polymeric paramagnetic complex with bridging uranium sulfides, while that with CS2 results in oxidation of each UIII to the notably high UV oxidation state, forming the unusual trithiocarbonate (CS3)2- as a ligand in [{U(CS3)}2(?-?2:?2-CS3)(LA)] (4). The reaction between 2-K and S8 results in quantitative substitution of the endo-KBH4 by a bridging persulfido (S2)2- group and oxidation of each UIII to UIV, yielding [{U(OAr)}2(?-?2:?2-S2)(LA)] (5). The reaction of 2-K with CS2 affords a thermally unstable adduct which is tentatively assigned as containing a carbon disulfido (CS2)2- ligand bridging the two U centres (6a), but only the mono-bridged sulfido (S)2- complex [{U(OAr)}2(?-S)(LA)] (6) is isolated. The persulfido complex (5) can also be synthesised from the mono-bridged sulfido complex (6) by the addition of another equivalent of sulfur.
| S-EPMC6094157 | biostudies-literature
Project description:Salmon cartilage proteoglycan fractions have recently gained favor as ingredients of functional food and cosmetics. An optimal hot water method to extract proteoglycan from salmon cartilage has recently been developed. The extracted cartilage includes hyaluronan and collagen in addition to proteoglycan as counterparts that interact with each other. In this study, biochemical analyses and atomic force microscopical analysis revealed global molecular images of proteoglycan in the hot water extract. More than seventy percent of proteoglycans in this extract maintained their whole native structures. Hyaluronan purified from the hot water extract showed a distribution with high molecular weight similar to hyaluronan considered to be native hyaluronan in cartilage. The current data is evidence of the quality of this hot water cartilage extract.
| S-EPMC8056930 | biostudies-literature
Project description:Proteoglycan as isolated from bovine nasal septa is a partially aggregated complex containing linking factors. Two essential factors can be separated from proteoglycan subunits and resolved in a CsCl density gradient. Chondroitinase digestion of the purified proteoglycan subunits does not interfere with their aggregation when the linking factors are added.
| S-EPMC1177708 | biostudies-other
Project description:Aging is a main risk factor for osteoarthritis (OA). FoxO transcription factors protect against cellular and organismal aging, and FoxO expression in cartilage is reduced with aging and in OA. To investigate the role of FoxO in cartilage, Col2Cre-FoxO1, 3, and 4 single knockout (KO) and triple KO mice (Col2Cre-TKO) were analyzed. Articular cartilage in Col2Cre-TKO and Col2Cre-FoxO1 KO mice was thicker than in control mice at 1 or 2 months of age. This was associated with increased proliferation of chondrocytes of Col2Cre-TKO mice in vivo and in vitro. OA-like changes developed in cartilage, synovium, and subchondral bone between 4 and 6 months of age in Col2Cre-TKO and Col2Cre-FoxO1 KO mice. Col2Cre-FoxO3 and FoxO4 KO mice showed no cartilage abnormalities until 18 months of age when Col2Cre-FoxO3 KO mice had more severe OA than control mice. Autophagy and antioxidant defense genes were reduced in Col2Cre-TKO mice. Deletion of FoxO1/3/4 in mature mice using Aggrecan(Acan)-CreERT2 (AcanCreERT-TKO) also led to spontaneous cartilage degradation and increased OA severity in a surgical model or treadmill running. The superficial zone of knee articular cartilage of Col2Cre-TKO and AcanCreERT-TKO mice exhibited reduced cell density and markedly decreased Prg4 In vitro, ectopic FoxO1 expression increased Prg4 and synergized with transforming growth factor-? stimulation. In OA chondrocytes, overexpression of FoxO1 reduced inflammatory mediators and cartilage-degrading enzymes, increased protective genes, and antagonized interleukin-1? effects. Our observations suggest that FoxO play a key role in postnatal cartilage development, maturation, and homeostasis and protect against OA-associated cartilage damage.
| S-EPMC6204214 | biostudies-literature
Project description:The negatively charged proteoglycans (PG) provide compressive resistance to articular cartilage by means of their fixed charge density (FCD) and high osmotic pressure (?(PG)), and the collagen network (CN) provides the restraining forces to counterbalance ?(PG). Our objectives in this work were to: 1), account for collagen intrafibrillar water when transforming biochemical measurements into a FCD-?(PG) relationship; 2), compute ?(PG) and CN contributions to the compressive behavior of full-thickness cartilage during bovine growth (fetal, calf, and adult) and human adult aging (young and old); and 3), predict the effect of depth from the articular surface on ?(PG) in human aging. Extrafibrillar FCD (FCD(EF)) and ?(PG) increased with bovine growth due to an increase in CN concentration, whereas PG concentration was steady. This maturation-related increase was amplified by compression. With normal human aging, FCD(EF) and ?(PG) decreased. The ?(PG)-values were close to equilibrium stress (?(EQ)) in all bovine and young human cartilage, but were only approximately half of ?(EQ) in old human cartilage. Depth-related variations in the strain, FCD(EF), ?(PG), and CN stress profiles in human cartilage suggested a functional deterioration of the superficial layer with aging. These results suggest the utility of the FCD-?(PG) relationship for elucidating the contribution of matrix macromolecules to the biomechanical properties of cartilage.
| S-EPMC3175069 | biostudies-literature