ADAMTS-5 Deficiency Does Not Block Aggrecanolysis at Preferred Cleavage Sites in the Chondroitin Sulfate-Rich Region of Aggrecan

J Biol Chem. 2007 Mar 23;282(12):8632-40. doi: 10.1074/jbc.M605750200. Epub 2007 Jan 25.

Abstract

In the mouse, proteolysis in the aggrecan interglobular domain is driven by ADAMTS-5, and mice deficient in ADAMTS-5 catalytic activity are protected against aggrecan loss and cartilage damage in experimental models of arthritis. Here we show that despite ablation of ADAMTS-5 activity, aggrecanolysis can still occur at two preferred sites in the chondroitin sulfate-rich region. Retinoic acid was more effective than interleukin-1alpha (IL) in promoting cleavage at these sites in ADAMTS-5-deficient cartilage. These results suggest that cleavage at preferred sites in the chondroitin sulfate-rich region is mediated by ADAMTS-4 or an aggrecanase other than ADAMTS-5. Following retinoic acid or IL-1alpha stimulation of cartilage explants, aggrecan fragments in medium and extracts contained SELE(1279) or FREEE(1467) C-terminal sequences. Some SELE(1279) and FREEE(1467) fragments were retained in the cartilage, with intact G1 domains. Other SELE(1279) fragments were released into the medium and co-migrated with the (374)ALGS neoepitope, indicating they were aggrecanase-derived fragments. In contrast none of the FREEE(1467) fragments released into the medium co-migrated with the (374)ALGS neoepitope, suggesting that, despite their size, these fragments were not products of aggrecanase cleavage in the interglobular domain. ADAMTS-5, but not ADAMTS-1, -4, or -9, was up-regulated 8-fold by retinoic acid and 17-fold by IL-1alpha treatment. The data show that whereas ADAMTS-5 is entirely responsible for cleavage in the interglobular domain, cleavage in the chondroitin sulfate-rich region is driven either by ADAMTS-4, which compensates for loss of ADAMTS-5 in this experimental system, or possibly by another aggrecanase. The data show that there are differential aggrecanase activities with preferences for separate regions of the core protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAM Proteins / deficiency
  • ADAM Proteins / genetics*
  • ADAM Proteins / physiology*
  • ADAMTS4 Protein
  • ADAMTS5 Protein
  • Aggrecans / chemistry*
  • Amino Acid Sequence
  • Animals
  • Cartilage / metabolism
  • Chondrocytes / metabolism
  • Chondroitin Sulfates / chemistry*
  • Epitopes / chemistry
  • Interleukin-1alpha / metabolism
  • Mice
  • Molecular Sequence Data
  • Procollagen N-Endopeptidase / physiology
  • Protein Binding
  • Protein Structure, Tertiary

Substances

  • Aggrecans
  • Epitopes
  • Interleukin-1alpha
  • Chondroitin Sulfates
  • ADAM Proteins
  • ADAMTS5 Protein
  • Adamts5 protein, mouse
  • Procollagen N-Endopeptidase
  • ADAMTS4 Protein
  • Adamts4 protein, mouse