scholarly journals Age-related changes in the composition, the molecular stoichiometry and the stability of proteoglycan aggregates extracted from human articular cartilage

2003 ◽  
Vol 370 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Terri WELLS ◽  
Catherine DAVIDSON ◽  
Matthias MÖRGELIN ◽  
Joseph L.E. BIRD ◽  
Michael T. BAYLISS ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Chloride Concentration ◽  
Human Articular Cartilage ◽  
Guanidinium Chloride ◽  
Link Protein ◽  
Molar Ratios ◽  
Age Related ◽  
Proteoglycan Aggregates ◽  
High Concentrations ◽  
The Stability

The heterogeneity of the components of proteoglycan aggregates, their stoichiometry within the aggregate and the aggregates’ stability was investigated in normal human articular cartilage specimens (age-range newborn to 63 years). Proteoglycans were extracted from tissue by sequentially extracting them with PBS alone, PBS containing oligosaccharides of hyaluronan, and PBS containing solutions of increasing guanidinium chloride concentration (1M, 2M, 3M and 4M). A high proportion of each of the components of the proteoglycan aggregate, i.e. uronic acid, sulphated glycosaminoglycan, hyaluronan binding domain of aggrecan (G1-domain), link protein (LP) and hyaluronan, was extracted from immature cartilage by PBS alone and PBS containing oligosaccharides of hyaluronan. This was in marked contrast to adult cartilage, which required high concentrations of guanidinium chloride for the efficient extraction of these components. The molar ratios of total G1-domain:LP and the G1-domain associated with aggrecan:LP also differed markedly between immature and mature cartilage and between each of the sequential extracts. The concentration of LP was less than that of the G1-domain in all extracts of cartilage from individuals over 13 years, but this was particularly noticeable in the 1M guanidinium chloride extracts, and it was surmised that a deficiency in LP produces unstable aggregates in situ. The fragmentation of LP, which is known to occur with advancing age, did not influence the extractability of LP, and fragments were present in each of the sequential extracts. Therefore the generally accepted model of proteoglycan aggregation presented in the literature, which is mostly derived from analysis of immature animal cartilage, cannot be used to describe the structure and organization of aggregates in adult human articular cartilage, where a heterogeneous population of complexes exist that have varying degrees of stability.

scholarly journals Age-related changes in the synthesis of link protein and aggrecan in human articular cartilage: implications for aggregate stability

1998 ◽  
Vol 337 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Mark C. BOLTON ◽  
Jayesh DUDHIA ◽  
Michael T. BAYLISS
Keyword(s):  
Articular Cartilage ◽  
De Novo ◽  
Core Protein ◽  
Buoyant Density ◽  
Aggregate Stability ◽  
Exchange Chromatography ◽  
Human Articular Cartilage ◽  
Post Translational Modification ◽  
Link Protein ◽  
Age Related

The rates of incorporation of radiolabelled leucine into aggrecan and link protein have been measured in human articular cartilage of different ages. Aggrecan and link protein were purified in the A1 fraction of CsCl gradients as a result of their ability to form high-buoyant-density proteoglycan aggregates with hyaluronic acid. Separation of the aggrecan from the link protein was achieved by Mono Q anion-exchange chromatography. The rates of synthesis of both aggrecan and link protein decreased with age. The age-related decrease in synthesis of aggrecan was paralleled by a decrease in the rate of sulphate incorporation into glycosaminoglycan chains. The synthesis of link protein decreased with age to a greater extent than that of aggrecan such that the ratio of the rates of link protein to aggrecan synthesis decreased from 1 in immature cartilage to 0.2 in mature cartilage. The age-related decrease in link protein synthesis is controlled at least in part by transcriptional or post-trancriptional mechanisms, as shown by the accompanying age-related decrease in link-protein mRNA. The absence of any age-related decrease in aggrecan mRNA suggests that the decrease in synthesis of aggrecan core protein is controlled by a translational mechanism. Measurement of the total tissue content of aggrecan and link protein by radioimmunoassay revealed an age-related increase in the accumulation of these matrix proteins, even though their de novo synthesis was decreasing. This illustrates the importance that the regulation of extracellular post-translational modification also has in controlling the overall turnover of the cartilage matrix.

scholarly journals Quantification of aggrecan and link-protein mRNA in human articular cartilage of different ages by competitive reverse transcriptase-PCR

1996 ◽  
Vol 319 (2) ◽  
pp. 489-498 ◽  
Author(s):  
Mark C BOLTON ◽  
Jayesh DUDHIA ◽  
Michael T BAYLISS
Keyword(s):  
Articular Cartilage ◽  
Reverse Transcriptase ◽  
Mrna Expression ◽  
Northern Hybridization ◽  
Human Articular Cartilage ◽  
Rt Pcr ◽  
Link Protein ◽  
Reverse Transcriptase Pcr ◽  
Age Related ◽  
Age Related Changes

A competitive reverse transcriptase–PCR (RT-PCR) assay has been developed for the quantification of particular mRNA species in human articular cartilage. Competitor RNA species were synthesized that differed from the amplified target sequence only by the central insertion of an EcoRI restriction site. By using known amounts of synthetic target and competitor RNA, it was shown that competitor RNA molecules designed in this way are reverse-transcribed and amplified with equal efficiency to the target of interest. Furthermore quantification could be performed during the plateau phase of the PCR, which was necessary when using ethidium bromide fluorescence as a detection system. The inhibition of aggrecan and link-protein mRNA expression by interleukin 1 or tumour necrosis factor in monolayers of human articular chondrocytes quantified by this competitive RT-PCR method compared favourably with Northern hybridization studies. The main advantage of this technique is that it can be used to quantify levels of mRNA with RNA extracted directly from 100 mg wet weight of human articular cartilage. Age-related changes in aggrecan and link-protein mRNA were therefore quantified in human articular cartilage directly after dissection from the joint. The concentration of link-protein mRNA was higher in immature cartilage than in mature cartilage when expressed relative to the amount of glyceraldehyde-3-phosphate dehydrogenase mRNA, but no age-related changes were observed in aggrecan mRNA expression. The ratio of aggrecan to link-protein mRNA was higher in mature cartilage than in immature tissue. These age-related differences in the molecular stoichiometry of aggrecan and link-protein mRNA might have implications with respect to the regulation of the formation and the stability of the proteoglycan aggregates in cartilage.

scholarly journals Age-related changes in the content of the C-terminal region of aggrecan in human articular cartilage

1996 ◽  
Vol 313 (3) ◽  
pp. 933-940 ◽  
Author(s):  
Jayesh DUDHIA ◽  
Catherine M. DAVIDSON ◽  
Terri M. WELLS ◽  
Demis H. VYNIOS ◽  
Timothy E. HARDINGHAM ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Terminal Region ◽  
Human Articular Cartilage ◽  
Amino Acid Residues ◽  
Turnover Rates ◽  
Human Cartilage ◽  
Age Related ◽  
Sds Page ◽  
High Concentrations ◽  
Age Related Changes

The content of the C-terminal region of aggrecan was investigated in samples of articular cartilage from individuals ranging in age from newborn to 65 years. This region contains the globular G3 domain which is known to be removed from aggrecan in mature cartilage, probably by proteolytic cleavage, but the age-related changes in its abundance in human cartilage have not been described previously. The analysis was performed by immunosorbant assay using an antiserum (JD5) against recombinant protein expressed from a cDNA clone encoding the terminal 598 amino acid residues of human aggrecan, on crude extracts of cartilage without further purification of aggrecan. The results showed that the content of the C-terminal region decreased with age relative to the G1 domain content (correlation coefficient = 0.463). This represented a 92% fall in the content of this region of the molecule from newborn to 65 years of age. Furthermore, when the G1 content of the cartilage extracts was corrected to only include the G1 attached to aggrecan and to exclude the G1 fragments which accumulate as a by-product of normal aggrecan turnover (free G1), the age-related decrease in the C-terminal region remained very pronounced. Analysis by composite agarose/PAGE showed that the number of subpopulations of aggrecan resolved increased from one in newborn to three in adult cartilage. All of these reacted with an antiserum to the human G1 domain, but only the slowest migrating species reacted with the C-terminal region antiserum (JD5). Similar analysis by SDS/PAGE confirmed the presence of high-molecular-mass (200 kDa) proteins reactive with JD5, but no reactive fragments of lower electrophoretic mobility were detected. In contrast, when probed with the antiserum to the human G1 domain, the immunoblots showed protein species corresponding to the free G1 and G1-G2 fragments, which were present at high concentrations in adult cartilage. The results suggest that the loss of the C-terminal region is not directly part of the process of aggrecan turnover, but it is a slow independent matrix process that occurs more extensively with aging as turnover rates become slower. Young cartilage with the fastest turnover contains least molecules lacking the C-terminal region, whereas in old tissue with slow turnover few molecules retain this region. An increase in the cleavage of this region with age may also contribute to this change. The content of the C-terminal region may thus give a measure of the abundance of newly synthesized aggrecan.

scholarly journals Age-related decrease in the link-stability of proteoglycan aggregates formed by articular chondrocytes

1984 ◽  
Vol 220 (1) ◽  
pp. 337-340 ◽  
Author(s):  
A H K Plaas ◽  
J D Sandy
Keyword(s):  
Protein Synthesis ◽  
Articular Cartilage ◽  
Proliferative Activity ◽  
Monolayer Culture ◽  
Articular Chondrocytes ◽  
Link Protein ◽  
Age Related ◽  
Link Stability ◽  
Proteoglycan Aggregates

Chondrocytes were isolated from the articular cartilage of rabbits aged between 6 and 50 weeks and labelled with [35S]sulphate after 48 h in monolayer culture. The percentage of the total proteoglycan monomers synthesized by each culture that were present as link-stabilized aggregates was shown to be about 83% at 6, 9 and 12 weeks, 73% at 15 weeks, 48% at 30 weeks and 32% at 50 weeks. The proliferative activity of the cells in culture also decreased markedly with the age of the donor. The results suggest that aging of chondrocytes in vivo is accompanied by a decrease in their capacity for link-protein synthesis.

scholarly journals Age-related accumulation of Maillard reaction products in human articular cartilage collagen

2000 ◽  
Vol 350 (2) ◽  
pp. 381 ◽  
Author(s):  
Nicole VERZIJL ◽  
Jeroen DEGROOT ◽  
Esther OLDEHINKEL ◽  
Ruud A. BANK ◽  
Suzanne R. THORPE ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Maillard Reaction ◽  
Maillard Reaction Products ◽  
Human Articular Cartilage ◽  
Reaction Products ◽  
Age Related

scholarly journals The properties of proteoglycan prepared from human articular cartilage by using associative caesium chloride gradients of high and low starting densities

1985 ◽  
Vol 232 (1) ◽  
pp. 111-117 ◽  
Author(s):  
M T Bayliss ◽  
P J Roughley
Keyword(s):  
Hyaluronic Acid ◽  
Articular Cartilage ◽  
Proteinase Inhibitors ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Human Articular Cartilage ◽  
Adult Human ◽  
Cscl Density Gradient ◽  
Proteoglycan Aggregates ◽  
Hyaluronic Acid Binding

Proteoglycan was extracted from adult human articular cartilage from both the knee and the hip, and A1 preparations were prepared by CsCl-density-gradient centrifugation at starting densities of 1.69 and 1.5 g/ml. Irrespective of whether the cartilage was diced to 1 mm cubes or sectioned to 20 micron slices there was always a lower proportion of both protein and proteoglycan aggregate in the A1 preparation prepared at 1.69 g/ml. Furthermore, the addition of exogenous hyaluronic acid to the extracts before centrifugation did not improve the yield of aggregate at 1.69 g/ml. These results were not affected by the presence of proteinase inhibitors in the extraction medium. It appears that adult human articular cartilage contains a high proportion of low-density proteoglycan subunits and hyaluronic acid-binding proteins that make most of the re-formed proteoglycan aggregates of a lower density than is usually encountered with younger human and mammalian hyaline cartilages.

scholarly journals Age-related changes in the composition and structure of human articular-cartilage proteoglycans

1978 ◽  
Vol 176 (3) ◽  
pp. 683-693 ◽  
Author(s):  
M T Bayliss ◽  
S Y Ali
Keyword(s):  
Hyaluronic Acid ◽  
Articular Cartilage ◽  
Age Groups ◽  
Human Articular Cartilage ◽  
Human Cartilage ◽  
Keratan Sulphate ◽  
Age Related ◽  
Composition And Structure ◽  
Normal Human ◽  
Cartilage Proteoglycans

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.

scholarly journals Biosynthesis of proteoglycan in vitro by cartilage from human osteochondrophytic spurs

1982 ◽  
Vol 206 (2) ◽  
pp. 329-341 ◽  
Author(s):  
Charles J. Malemud ◽  
Victor M. Goldberg ◽  
Roland W. Moskowitz ◽  
Lee L. Getzy ◽  
Robert S. Papay ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Articular Cartilage ◽  
Deae Cellulose ◽  
Culture Conditions ◽  
Human Articular Cartilage ◽  
Guanidinium Chloride ◽  
Tissue Slices ◽  
Keratan Sulphate ◽  
Defined Culture

Proteoglycan biosynthesis by human osteochondrophytic spurs (osteophytes) obtained from osteoarthritic femoral heads at the time of surgical joint replacement was studied under defined culture conditions in vitro. Osteophytes were primarily present in two anatomic locations, marginal and epi-articular. Minced tissue slices were incubated in the presence of [35S]sulphate or [14C]glucosamine. Osteophytes incorporated both labelled precursors into proteoglycan, which was subsequently characterized by CsCl-isopycnic-density-gradient ultracentrifugation and chromatography on Sepharose CL-2B. The material extracted with 0.5m-guanidinium chloride showed 78.1% of [35S]sulphate in the A1 fraction after centrifugation. Only 23.0% of the [35S]sulphate in this A1 fraction was eluted in the void volume of Sepharose CL-2B under associative conditions. About 60–80% of the [35S]sulphate in the tissue 4m-guanidinium chloride extract was associated with monomeric proteoglycan (fraction D1). The average partition coefficient (Kav.) of the proteoglycan monomer on Sepharose CL-2B was 0.28–0.33. Approx. 12.4% of this monomer formed stable aggregates with high-molecular-weight hyaluronic acid in vitro. Sepharose CL-2B chromatography of fractions with lower buoyant densities (fractions D2–D4) demonstrated elution profiles on Sepharose CL-2B substantially different than that of fraction D1, indicative of the polydisperse nature of the newly synthesized proteoglycan. Analysis of the composition and chain size of the glycosaminoglycans showed the following: (1) preferential elution of both [35S]sulphate and [14C]glucosamine in the 0.5m-LiCl fraction on DEAE-cellulose; (2) the predominant sulphated glycosaminoglycan was chondroitin 6-sulphate (60–70%), with 9–11% keratan sulphate in the monomer proteoglycan; (3) Kav. values of 0.38 on Sephadex G-200 and 0.48 on Sepharose CL-6B were obtained with papain-digested and NaBH4-treated D1 monomer respectively. A comparison of the synthetic with endogenous glycosaminoglycans indicated similar types. These studies indicated that human osteophytes synthesized in vitro sulphated proteoglycans with some characteristics similar to those of mature human articular cartilage, notably in the size of their proteoglycan monomer and predominance of chondroitin 6-sulphate. They differed from articular cartilage primarily in the lack of substantial quantities of keratan sulphate and aggregation properties associated with monomer interaction with hyaluronic acid.

Sign in / Sign up

Export Citation Format

Share Document