Evidence of a novel aggrecan‐degrading activity in cartilage: Studies of mice deficient in both ADAMTS‐4 and ADAMTS‐5

Abstract

Objective. To characterize aggrecan catabolism and the overall phenotype in mice deficient in both ADAMTS-4 and ADAMTS-5 (TS-4/TS-5 ⌬-cat) activity.Methods. Femoral head cartilage from the joints of TS-4/TS-5 ⌬-cat mice and wild-type mice were cultured in vitro, and aggrecan catabolism was stimulated with either interleukin-1␣ (IL-1␣) or retinoic acid. Total aggrecan release was measured, and aggrecanase activity was examined by Western blotting using neoepitope antibodies for detecting cleavage at EGE 373 Conclusion. An aggrecanase other than ADAMTS-4 and ADAMTS-5 is expressed in mouse cartilage and is up-regulated by retinoic acid but not IL-1␣. The novel aggrecanase appears to have different substrate specificity from either ADAMTS-4 or ADAMTS-5, cleaving E-G bonds but not E-A bonds. Neither ADAMTS-4 nor ADAMTS-5 is required for normal skeletal development or aggrecan turnover in cartilage.Loss of aggrecan from cartilage is an early event in arthritis that precedes radiographic evidence of cartilage destruction. It is driven primarily by aggrecanases that cleave at a number of sites in the aggrecan core protein. In diseased tissue, the most important cleavage site is in the interglobular domain (IGD), between the N-terminal G1 and G2 globular domains. Aggrecan binding to hyaluronan via its G1 domain tethers aggrecan in the matrix, and cleavage in the IGD results in loss of the entire glycosaminoglycan-containing region, with an associated loss of aggrecan function. The term aggrecanase was first used to describe the activity that cleaves aggrecan in the IGD between E 373 and A 374 (1-3). Aggrecan fragments that are cleaved at this site have been identified in synovial fluid from patients with osteoarthritis, inflammatory joint disease, and/or knee injury (4,5). Matrix metalloproteinases (MMPs) cleave in the IGD between N 341 and F 342 (6), and fragments

Chondrocytic EphrinB2 promotes cartilage destruction by osteoclasts in endochondral ossification

“…5B). Hypertrophic chondrocytes also promote the destruction of growth plate cartilage by expression of a number of catabolic enzymes, including the matrix metalloproteinases (MMPs) MMP13 (Johansson et al, 1997) and MMP9 (Shinoda et al, 2008;Golovchenko et al, 2013) and the aggrecanases ADAMTS4 and ADAMTS5 (Glasson et al, 2004;Rogerson et al, 2008). We reasoned that, since ephrin B2 deletion was targeted to osteoblasts and chondrocytes, the lack of cartilage destruction in Osx1Cre.…”

Versican Processing by a Disintegrin-like and Metalloproteinase Domain with Thrombospondin-1 Repeats Proteinases-5 and -15 Facilitates Myoblast Fusion

“…Despite combinatorial deletion of five alleles of three Adamts genes in mice (Adamst5, Adamts20, and Adamts9), skeletal muscle dysfunction was not elucidated (20). Adamts4 and Adamts5 combinatorial knockout mice have been previously reported as having no overt skeletal muscle myopathy (20,47) further suggesting a compensating role for Adamts15 during skeletal muscle development.…”

Metalloproteinases and Metalloproteinase Inhibitors in Age-Related Diseases

“…Conversely, the role of ADAMTS-4 as aggrecanase appears more evident in humans [441,442]. It has then been observed that ADAMTS-4 mRNA is induced in chondrocytes by IL-1 [443], while Adamts-4/Adamts-5 double knockout mice are protected from cartilage degradation by IL-1, but not by retinoic acid, suggesting that other aggrecans apart from ADAMTS-4 and -5 are capable of retinoic acid-induced cartilage breakdown, at least in animal models [444]. In addition, suppressing ADAMTS-4 and/or ADAMTS-5 in human cartilage explants, via transfection of these ADAMTSs by siRNAs, significantly decreased aggrecan release and catabolism induced by a combination of IL-1 , TNF-and oncostatin M [441].…”