LRP-1-mediated endocytosis regulates extracellular activity of ADAMTS-5 in articular cartilage

Kazuhiro Yamamoto, Linda Troeberg, Simone D Scilabra, Michele Pelosi, Christopher L Murphy, Dudley K Strickland, Hideaki Nagase

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Aggrecan is a major matrix component of articular cartilage, and its degradation is a crucial event in the development of osteoarthritis (OA). Adamalysin-like metalloproteinase with thrombospondin motifs 5 (ADAMTS-5) is a major aggrecan-degrading enzyme in cartilage, but there is no clear correlation between ADAMTS-5 mRNA levels and OA progression. Here, we report that post-translational endocytosis of ADAMTS-5 by chondrocytes regulates its extracellular activity. We found 2- to 3-fold reduced aggrecanase activity when ADAMTS-5 was incubated with live porcine cartilage, resulting from its rapid endocytic clearance. Studies using receptor-associated protein (RAP), a ligand-binding antagonist for the low-density lipoprotein receptor-related proteins (LRPs), and siRNA-mediated gene silencing revealed that the receptor responsible for ADAMTS-5 clearance is LRP-1. Domain-deletion mutagenesis of ADAMTS-5 identified that the noncatalytic first thrombospondin and spacer domains mediate its endocytosis. The addition of RAP to porcine cartilage explants in culture increased the basal level of aggrecan degradation, as well as ADAMTS-5-induced aggrecan degradation. Notably, LRP-1-mediated endocytosis of ADAMTS-5 is impaired in chondrocytes of OA cartilage, with ∼90% reduction in protein levels of LRP-1 without changes in its mRNA levels. Thus, LRP-1 dictates physiological and pathological catabolism of aggrecan in cartilage as a key modulator of the extracellular activity of ADAMTS-5.

Original languageEnglish
Pages (from-to)511-521
Number of pages11
JournalThe FASEB Journal
Volume27
Issue number2
Early online date11 Oct 2012
DOIs
Publication statusPublished - 1 Feb 2013

Keywords

  • ADAM Proteins/chemistry
  • ADAMTS5 Protein
  • Aged
  • Aggrecans/metabolism
  • Animals
  • Cartilage, Articular/metabolism
  • Endocytosis/physiology
  • Extracellular Matrix/metabolism
  • Female
  • Gene Knockdown Techniques
  • Humans
  • LDL-Receptor Related Protein-Associated Protein/metabolism
  • Low Density Lipoprotein Receptor-Related Protein-1/antagonists & inhibitors
  • Male
  • Middle Aged
  • Mutagenesis
  • Osteoarthritis/etiology
  • Protein Structure, Tertiary
  • RNA, Messenger/genetics
  • RNA, Small Interfering/genetics
  • Swine

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