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Variations in aggrecan structure modulate its susceptibility to aggrecanases
Peter J Roughley1, James Barnett, Fengrong Zuo
1Shriners Hospital for Children, 1529 Cedar Avenue, Montreal, Quebec, Canada H3G 1A6. proughley@shriners.mcgill.ca
The Biochemical Journal
|July 16, 2003
Summary
Aggrecanase-2 effectively cleaves aggrecan in the interglobular domain across ages, while aggrecanase-1 is less efficient on immature aggrecan. Cleavage efficiency varies by species, age, and aggrecanase type.
Area of Science:
- Biochemistry
- Molecular Biology
- Biomaterials Science
Background:
- Aggrecan is a major proteoglycan in cartilage, crucial for tissue structure and function.
- Aggrecanases are key enzymes involved in aggrecan degradation, implicated in cartilage diseases.
- Understanding aggrecanase activity is vital for developing treatments for cartilage degeneration.
Purpose of the Study:
- To investigate the in vitro degradation of aggrecan by aggrecanase-1 and aggrecanase-2.
- To compare the cleavage efficiency of aggrecanases on aggrecan from different species and ages.
- To determine the impact of aggrecan form (isolated vs. aggregate) on aggrecanase activity.
Main Methods:
- In vitro degradation assays using purified aggrecan and proteoglycan aggregates.
- Enzymatic digestion with recombinant aggrecanase-1 and aggrecanase-2.
- Analysis of cleavage products using SDS/PAGE and immunoblotting.
Main Results:
- Aggrecanase-2 showed consistent cleavage in the interglobular domain (IGD) of aggrecan from adult and immature sources (bovine and human).
- Aggrecanase-1 exhibited reduced efficiency in cleaving the IGD of immature aggrecan from both species.
- Both aggrecanases cleaved the chondroitin sulphate-rich domain 2 (CS2) of bovine aggrecan similarly across ages but were less effective on human aggrecan CS2.
- Neither aggrecanase cleaved link protein within proteoglycan aggregates.
Conclusions:
- Aggrecan cleavage by aggrecanases is influenced by the species and age of the aggrecan source.
- Aggrecanase-2 demonstrates broader substrate specificity for the IGD compared to aggrecanase-1, particularly with immature aggrecan.
- These findings highlight the differential activity of aggrecanases and are relevant for understanding cartilage matrix turnover and disease pathogenesis.