Hyaluronate degradation as an alternative mechanism for proteoglycan release from cartilage during interleukin-1β-stimulated catabolism (original) (raw)
Research Article| February 22 2002
∗Joint Diseases Laboratory, Shriners Hospital for Children, McGill University, Montreal, Quebec, Canada H3G 1A6
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∗Joint Diseases Laboratory, Shriners Hospital for Children, McGill University, Montreal, Quebec, Canada H3G 1A6
†Department of Surgery, McGill University, Montreal, Quebec, Canada H3G 1A6
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†Department of Surgery, McGill University, Montreal, Quebec, Canada H3G 1A6
‡Genetics Unit, Shriners Hospital for Children, Department of Surgery, McGill University, Montreal, Quebec, Canada H3G 1A6
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∗Joint Diseases Laboratory, Shriners Hospital for Children, McGill University, Montreal, Quebec, Canada H3G 1A6
†Department of Surgery, McGill University, Montreal, Quebec, Canada H3G 1A6
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Publisher: Portland Press Ltd
Received: April 20 2001
Revision Received: October 26 2001
Accepted: December 13 2001
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 362 (2): 473–479.
Revision Received:
October 26 2001
Accepted:
December 13 2001
Data presented previously suggest that release of components of the cartilage matrix, in response to catabolic agents, cannot be accounted for by proteolytic mechanisms alone. In the present study, the release of glycosaminoglycan-containing components from bovine nasal cartilage cultured in the presence of interleukin-1β, and from bovine nasal, fetal bovine epiphyseal and adult human articular cartilage cultured in the presence of retinoic acid, was accompanied by the loss of link protein and hyaluronate into the culture medium. Chromatographic analysis of the released hyaluronate showed it to be markedly reduced in size relative to that extracted from the corresponding tissue. It is proposed that, under stimulation by catabolic agents, two independent, but concurrent, mechanisms act to promote the release of aggrecan from the cartilage matrix. First, proteolytic cleavage of the aggrecan core protein results in the production of glycosaminoglycan-containing fragments that are free to diffuse from the tissue. Secondly, cleavage of hyaluronate renders portions of the proteoglycan aggregate small enough so that complexes of aggrecan (or fragments containing its G1 domain) and link protein are released from the tissue. It is likely that both mechanisms contribute to cartilage metabolism in normal physiology and pathology.
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The Biochemical Society, London ©2002
2002
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