The role of ADAM-TS4 (aggrecanase-1) and ADAM-TS5 (aggrecanase-2) in a model of cartilage degradation.
BACKGROUND
Cleavage of aggrecan between residues Glu(373)-Ala(374), which is believed to be a key event in aggrecan destruction in arthritic diseases, has been attributed to an enzymatic activity, aggrecanase. Two cartilage aggrecanases have been identified, aggrecanase-1 (ADAM-TS4) and aggrecanase-2 (ADAM-TS5) and both enzymes have been shown very efficiently to cleave soluble aggrecan at the Glu(373)-Ala(374) site.


OBJECTIVE
To determine whether ADAM-TS4 and/or ADAM-TS5 are the aggrecanases responsible for aggrecan catabolism following interleukin-1 (IL-1) and tumor necrosis factor (TNF) treatment of bovine articular cartilage.


RESULTS
(1) IL-1- and TNF-stimulated release of aggrecan was associated with cleavage of aggrecan within the C-terminus at the ADAM-TS4 and ADAM-TS5-sensitive sites, Glu(1480)-Gly(1481), Glu(1667)-Gly(1668), and Glu(1871)-Leu(1872). (2) The order of cleavage following IL-1 stimulation of cartilage explants was the same as when soluble aggrecan is digested with recombinant human ADAM-TS4 and ADAM-TS5. (3) Both constitutive and stimulated cleavage of aggrecan at the ADAM-TS4 and ADAM-TS5-sensitive sites in cartilage was blocked by a general metalloproteinase inhibitor but not by a MMP-specific inhibitor, and this inhibition correlated with inhibition of aggrecan release from cartilage. (4) PCR and Western blot analysis indicated that both ADAM-TS proteases are expressed in cartilage explants; ADAM-TS5 is constitutively expressed whereas ADAM-TS4 is induced following IL-1 and TNF treatment. (5) Immunodepletion of both ADAM-TS4 and ADAM-TS5 from bovine articular cartilage cultures following IL-1 stimulation resulted in a 90% reduction of aggrecanase activity in the culture medium.
Tortorella
M D
MD
DuPont Pharmaceuticals Company, Wilmington, DE 19880-0400, USA. micky.d.tortorella@pharmacia.com
Malfait
A M
AM
Deccico
C
C
Arner
E
E
D051722:ADAM Proteins; D000071121:ADAMTS4 Protein; D053674:Aggrecans; D000818:Animals; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000166:cytology / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins; D007375:Interleukin-1 / Q000502:physiology; D037181:Lectins, C-Type; D008666:Metalloendopeptidases / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011348:Procollagen N-Endopeptidase; D011509:Proteoglycans / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D007375:Interleukin-1; D037181:Lectins, C-Type; D011509:Proteoglycans; D019714:Tissue Inhibitor of Metalloproteinases; D014409:Tumor Necrosis Factor-alpha; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D011348:Procollagen N-Endopeptidase; D000071121:ADAMTS4 Protein