Mechanism of catabolism of aggrecan by articular cartilage

Ilic, Mirna Z.; Handley, Christopher J.; Robinson, H C; Mok, Meng Tuck

doi:10.1016/0003-9861(92)90144-l

Cited by 180 publications

(169 citation statements)

References 17 publications

Supporting

Mentioning

157

Contrasting

Order By: Relevance

“…Thus, in all cultures in which an increase in the release of aggrecan was detected using the DMMB assay (Table 1), there was an increase in BC-3-reactive metabolites. These results confirm previous findings demonstrating that catabolic stimulation of cartilage explants results in an increase in aggrecanase-generated aggrecan metabolites in the culture media [12,[20][21][22][23][24][25]. No BC-3-positive bands were observed above 250 kDa, indicating that the highmolecular-mass bands observed with MAb 2-B-6 had not been cleaved within the IGD.…”

Section: Proteoglycan Catabolism In 4-day Cultures Of Bovine and Porcsupporting

confidence: 91%

“…The proteoglycan metabolites released into Figure 1A) ranged in molecular mass from 250 kDa to approx. 90 kDa, as has been previously described [21]. In stimulated cultures there was a decrease in the high-molecularmass 2-B-6-positive bands ( Figure 1A) ; however, the banding pattern was not markedly different between the three catabolic agents, suggesting that similar cleavages of the core protein were occurring regardless of the stimuli used.…”

Section: Proteoglycan Catabolism In 4-day Cultures Of Bovine and Porcsupporting

confidence: 83%

“…In attempts to elucidate the actual sequence of catabolic events, researchers have studied in itro models of normal and accelerated aggrecan catabolism using either cartilage explants or chondrocyte monolayer cultures exposed to catabolic agents such as retinoic acid (RA), interleukin-1 (IL-1) or tumour necrosis factor-α (TNF) [12,[20][21][22][23][24][25]. However, no studies have simultaneously evaluated the generation of the N-and C-terminal neoepitopes which result from the action of both aggrecanase and MMPs in itro.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Aggrecanase versus matrix metalloproteinases in the catabolism of the interglobular domain of aggrecan in vitro

Little

Flannery

Hughes

et al. 1999

Biochemical Journal

115

View full text Add to dashboard Cite

The importance of aggrecanase versus matrix metalloproteinase (MMP) enzymic activities in the degradation of aggrecan in normal and osteoarthritic (OA) articular cartilage in vitro was studied in order to further our understanding of the potential role of these two enzyme activities in aggrecan catabolism during the pathogenesis of cartilage degeneration. Porcine and bovine articular cartilage was maintained in explant culture for up to 20 days in the presence or absence of the catabolic stimuli retinoic acid, interleukin-1 or tumour necrosis factor-α. Release of proteoglycan from cartilage was measured as glycosaminoglycan (GAG) release using a colorimetric assay. Analysis of proteoglycan degradation products, both released into culture media and retained within the cartilage matrix, was performed by Western blotting using antibodies specific for the N- and C-terminal neoepitopes generated by aggrecanase- and MMP-related catabolism of the interglobular domain of the aggrecan core protein (IGD). In addition, studies determining the mRNA expression for MMP-3 and MMP-13 in these same cultures were undertaken. These analyses indicated that all three catabolic agents stimulated the release of > 80% of the GAG from the articular cartilage over 4 days. The degree of GAG release corresponded to an increase in aggrecanase-generated aggrecan catabolites released into the media and retained within the cartilage. Importantly, there was no evidence for the release of MMP-generated aggrecan metabolites into the medium, nor the accumulation of MMP-generated catabolites within the tissue in these same cultures. Expression of the mRNAs for two MMPs known to be capable of degrading the aggrecan IGD, MMP-3 and MMP-13, was detected. However, increased expression of these MMPs was not correlated with aggrecan degradation. Analyses using porcine cartilage, cultured with or without catabolic stimulation for 12 h to 20 days, indicated that primary cleavage of the IGD by aggrecanase was responsible for release of aggrecan metabolites at both the early and late time points of culture. Cultures of late-stage OA human articular cartilage samples indicated that aggrecanase activity was upregulated in the absence of catabolic stimulation when compared with normal porcine or bovine cartilage. In addition, even in this late-stage degenerate cartilage, aggrecanase and not MMP activity was responsible for the release of the majority of aggrecan from the cartilage. This study demonstrates that the release of aggrecan from both normal and OA cartilage in response to catabolic stimulation in vitro involves a primary cleavage by aggrecanase and not MMPs.

show abstract

Section: Proteoglycan Catabolism In 4-day Cultures Of Bovine and Porcsupporting

confidence: 91%

Section: Proteoglycan Catabolism In 4-day Cultures Of Bovine and Porcsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Aggrecanase versus matrix metalloproteinases in the catabolism of the interglobular domain of aggrecan in vitro

Little

Flannery

Hughes

et al. 1999

Biochemical Journal

115

View full text Add to dashboard Cite

show abstract

“…However, since there is less structural and amino acid homology between the G1 and G2 domains than between the G1 domain and link protein, this seems unlikely (2). Studies analyzing the products of the catabolism of aggrecan in normal and diseased cartilage have shown that aggrecan is lost from cartilage by proteolytic cleavage at a specific site between the G1 and G2 domains of the core protein of this proteoglycan (31). This results in aggrecan fragments containing the G2 and GAG attachment regions being rapidly lost from the tissue, and because they do not contain the G1 domain, they will not show reactivity with these antibodies to the native G1 domain.…”

Section: Discussionmentioning

confidence: 99%

Presence of antibodies to native G1 domain of aggrecan core protein in synovial fluids from patients with various joint diseases

Karopoulos

Rowley

Ilic

et al. 1996

Arthritis & Rheumatism

Self Cite

View full text Add to dashboard Cite

Objective. To investigate the occurrence of IgG antibodies to aggrecan in synovial fluids (SF) from patients with arthritis and various articular diseases, and to determine the nature of epitopes present within aggrecan that react with these antibodies. Methods. SF samples were reacted with native aggrecan, reduced and alkylated aggrecan, chondroitin sulfate, and keratan sulfate, using dot‐blots and a novel enzyme‐linked immunosorbent assay (ELISA). The nature of the epitopes present on aggrecan was elucidated using Western blots and a competitive inhibition ELISA. Results. IgG antibodies to aggrecan were found in >50% of the SF samples tested. No IgG antibody reactivity was observed in serum from the same patients. The antibodies appeared to react predominantly with native aggrecan, and there was no disease specificity. It was shown that the epitopes to these antibodies were located within the N‐terminal region of the core protein. Conclusion. This study demonstrates the frequent occurrence of IgG antibodies to aggrecan in human SF. The major epitope is located in the G1 domain of the aggrecan core protein. These IgG antibodies appear to be produced locally within the synovial cavity, probably in response to various articular diseases, resulting in the loss of native aggrecan from articular cartilage.

show abstract

“…under conditions of normal and IL-1 stimulated turnover cartilage explants release aggrecan fragments with N-terminal sequences corresponding to cleavage between E373 and A374 [20][21][22]. The putative enzyme responsible for this cleavage has been named aggrecanase but its identity remains unknown.…”

Section: *Corresponding Author Fax: (61) (3) 9345 6668mentioning

confidence: 99%