Low density lipoprotein receptor-related protein 1 (LRP1)-mediated endocytic clearance of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4): functional differences of non-catalytic domains of ADAMTS-4 and ADAMTS-5 in LRP1 binding

• Published in: The Journal of biological chemistry Vol. 289; no. 10; pp. 6462 - 6474
• Main Authors: Yamamoto, Kazuhiro, Owen, Kathryn, Parker, Andrew E, Scilabra, Simone D, Dudhia, Jayesh, Strickland, Dudley K, Troeberg, Linda, Nagase, Hideaki
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 07.03.2014
• Subjects: ADAM Proteins - chemistry; ADAM Proteins - genetics; ADAM Proteins - metabolism; ADAMTS4 Protein; ADAMTS5 Protein; Animals; Cartilage, Articular - metabolism; Catalytic Domain - genetics; Cell Biology; Cells, Cultured; Endocytosis; Half-Life; Humans; Low Density Lipoprotein Receptor-Related Protein-1 - metabolism; Osteoarthritis - metabolism; Procollagen N-Endopeptidase - chemistry; Procollagen N-Endopeptidase - genetics; Procollagen N-Endopeptidase - metabolism; Protein Binding; Sequence Deletion; Swine; Endocytosis; Aggrecanase; Extracellular Matrix; Osteoarthritis; Trafficking; Chondrocytes
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.545376

Degradation of the cartilage proteoglycan aggrecan is an early event in the development of osteoarthritis, and a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) and ADAMTS-5 are considered to be the major aggrecan-degrading enzymes. We have recently found that ADAMTS-5 is rapidly endocytosed via low density lipoprotein receptor-related protein 1 (LRP1) and degraded by chondrocytes. Here we report that this regulatory mechanism also applies to ADAMTS-4, although its rate of endocytosis is slower than that of ADAMTS-5. Domain deletion mutagenesis of ADAMTS-4 identified that the cysteine-rich and spacer domains are responsible for binding to LRP1, whereas the thrombospondin 1 and spacer domains are responsible in ADAMTS-5. The estimated t½ value of ADAMTS-4 endocytosis was about 220 min, whereas that of ADAMTS-5 was 100 min. The difference in half-lives between the two enzymes is explained by the 13-fold lower affinity of ADAMTS-4 for LRP1 compared with that of ADAMTS-5. Studies using soluble ligand binding clusters of LRP1 showed that ADAMTS-4 binds to clusters II and IV with similar KD,app values of 98 and 73 nm, respectively, whereas ADAMTS-5 binds to cluster II, III, and IV with KD,app values of 3.5, 41, and 9 nm, respectively. Thus, ADAMTS-5 competitively inhibits ADAMTS-4 endocytosis but not vice versa. This study highlights that the affinity between a ligand and LRP1 dictates the rate of internalization and suggests that LRP1 is a major traffic controller of the two aggrecanases, especially under inflammatory conditions, where the protein levels of ADAMTS-4 increase, but those of ADAMTS-5 do not.