Cathepsin B: an alternative protease for the generation of an aggrecan ‘metalloproteinase’ cleavage neoepitope

Mort, John S.; Magny, Marie-Claude; Lee, Eunice R.

doi:10.1042/bj3350491

Cited by 90 publications

(53 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In day-20 cartilage extracts, however, an increase in the anti-DIPEN immunoreactivity was evident in extracts of cartilage cultured in the presence of IL-1 ( Figure 5C). Given that no BC-14-reactive catabolites could be detected in the media of these day-20 IL-1 cultures, it seems likely that the increase in DIPEN was associated with secondary catabolism of aggrecanase-generated G1 fragments by MMPs or cathepsin B [35]. Confirmation of such a secondary cleavage was not possible using the present methodologies, since proteolysis of aggrecanase-generated G1 fragments by MMPs or cathepsin B would result in the release of a small 32 amino acid … ITEGE-terminating fragment.…”

Section: Aggrecan Catabolism Associated With Different Times Of Culturementioning

confidence: 97%

“…Taken together, these results raise the possibility that detection of the … DIPEN neoepitope in articular cartilage may not be solely due to primary MMP-generated aggrecan release from articular cartilage, but could also result from secondary cleavage of aggrecanase-generated metabolites. In addition, it has recently been demonstrated that the … DIPEN neoepitope can be generated in itro by cathepsin B, in addition to the MMPs [35]. The generation of … DIPEN by cathepsin B was observed principally at acidic pH ( 5.5) ; however, sufficient exopeptidase activity of this enzyme remained at more neutral pH to eventually generate this neoepitope [35].…”

Section: Figure 4 Western Blot Analysis Of Aggrecan Fragments Generatmentioning

confidence: 99%

“…In addition, it has recently been demonstrated that the … DIPEN neoepitope can be generated in itro by cathepsin B, in addition to the MMPs [35]. The generation of … DIPEN by cathepsin B was observed principally at acidic pH ( 5.5) ; however, sufficient exopeptidase activity of this enzyme remained at more neutral pH to eventually generate this neoepitope [35]. Cathepsin B has been detected in normal articular cartilage and levels of this enzyme are increased in osteoarthritic cartilage [36].…”

Section: Figure 4 Western Blot Analysis Of Aggrecan Fragments Generatmentioning

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

Self Cite

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: Aggrecan Catabolism Associated With Different Times Of Culturementioning

confidence: 97%

Section: Figure 4 Western Blot Analysis Of Aggrecan Fragments Generatmentioning

confidence: 99%

Section: Figure 4 Western Blot Analysis Of Aggrecan Fragments Generatmentioning

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

Self Cite

115

View full text Add to dashboard Cite

show abstract

“…This domain has a rod-shaped structure in which contains proteolytic cleavage sites susceptible to a variety of proteinases such as matrix metalloproteinases (MMPs), serine proteinases such as plasmin and leukocyte elastase, and acid proteinases such as cathepsin B (cysteine protease) (Fig 4) [1], [29], [30]. The IGD domain is encoded by exon 7 of aggrecan.…”

Section: The Inter-globular Domain (Igd)mentioning

confidence: 99%

Structure and function of aggrecan

et al. 2002

View full text Add to dashboard Cite

Aggrecan is the major proteoglycan in the articular cartilage. This molecule is important in the proper functioning of articular cartilage because it provides a hydrated gel structure (via its interaction with hyaluronan and link protein) that endows the cartilage with load-bearing properties. It is also crucial in chondroskeletal morphogenesis during development. Aggrecan is a multimodular molecule expressed by chondrocytes. Its core protein is composed of three globular domains (G1, G2, and G3) and a large extended region (CS) between G2 and G3 for glycosaminoglycan chain attachment. G1 comprises the amino terminus of the core protein. This domain has the same structural motif as link protein. Functionally, the G1 domain interacts with hyaluronan acid and link protein, forming stable ternary complexes in the extracellular matrix. G2 is homologous to the tandem repeats of G1 and of link protein and is involved in product processing. G3 makes up the carboxyl terminus of the core protein. It enhances glycosaminoglycan modification and product secretion. Aggrecan plays an important role in mediating chondrocyte-chondrocyte and chondrocyte-matrix interactions through its ability to bind hyaluronan.

show abstract

“…One is a matrix metalloproteinase (MMP)-sensitive site at VDIPEN 341 2F 342 FGVGG, which can be cleaved at neutral pH by any one of a range of MMPs, including MMP-1-3, -7-9, -13, -14, -19, and -20, and also by the combined endopeptidase and carboxypeptidase activity of cathepsin B at low pH (14). Proteolytic fragments of aggrecan resulting from cleavage at this site have been isolated from normal articular tissue (10,15) and synovial fluids (16 -18).…”

mentioning

confidence: 99%

ADAMTS4 Cleaves at the Aggrecanase Site (Glu373-Ala374) and Secondarily at the Matrix Metalloproteinase Site (Asn341-Phe342) in the Aggrecan Interglobular Domain

Westling

Fosang

Thompson

et al. 2002

Journal of Biological Chemistry

View full text Add to dashboard Cite

Aggrecan is the major cartilage hyalectan (1), which, together with the collagen network, provides this tissue with its unique mechanical properties of compressibility and stiffness (2-4). Extraction of aggrecan in its native form (5) and subsequent structural analysis (6) have revealed that the molecular organization of aggrecan is perfectly suited to its central functional role in articular cartilage. The N-terminal region of aggrecan is composed of two globular domains (G1 1 and G2) separated by the interglobular domain (IGD). G1 interacts with hyaluronan and link protein, thereby keeping the aggrecan molecule anchored within the cartilage tissue. Further interactions with other matrix components such as tenascin-R and fibulin-1 and fibulin-2 (7, 8) may occur through a third globular domain (G3) at the extreme C terminus of the core protein. The extended core protein between G2 and G3 is composed of a short keratan sulfate-rich region followed by a longer chondroitin sulfate-substituted domain. The charge repulsion and hydration of the long negatively charged glycosaminoglycan (GAG) chains are thought to maintain the C-terminal portions of aggrecan in an extended conformation (9). The swelling pressure of the aggrecan-link protein complex with hyaluronan is restrained by the tension in the collagen network; and together, these components form a fiber-reinforced concentrated gel within the cartilage, which transmits forces across the articular joint.In diseases characterized by cartilage degradation such as rheumatoid arthritis and osteoarthritis, increased aggrecan release from the cartilage occurs early (10, 11) and before the bulk of the collagen network is degraded (12). Proteolytic cleavage of aggrecan within the IGD separates the GAG-rich region from the hyaluronan-anchored G1 domain, resulting in GAG release from the cartilage matrix to the synovial fluid. Biomechanical tests on cartilage discs have shown that proteolysis within the IGD of aggrecan, and not cleavages near the C terminus, is primarily responsible for the loss of compressive resistance that accompanies interleukin-1-mediated degradation of the tissue (13). Identification of the proteinases responsible for this "destructive" cleavage of aggrecan has therefore been a major focus of experimentation in arthritis-related research.In this regard, two major cleavage sites that occur in vivo have been identified in the IGD of human aggrecan. One is a matrix metalloproteinase (MMP)-sensitive site at VDIPEN 341 2F 342 FGVGG, which can be cleaved at neutral pH by any one of a range of MMPs, including MMP-1-3, -7-9, -13,

show abstract

Cathepsin B: an alternative protease for the generation of an aggrecan ‘metalloproteinase’ cleavage neoepitope

Cited by 90 publications

References 21 publications

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

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

Structure and function of aggrecan

ADAMTS4 Cleaves at the Aggrecanase Site (Glu373-Ala374) and Secondarily at the Matrix Metalloproteinase Site (Asn341-Phe342) in the Aggrecan Interglobular Domain

Contact Info

Product

Resources

About