Dynamic loading enhances integrative meniscal repair in the presence of interleukin-1
57
Citation
73
Reference
10
Related Paper
Citation Trend
Keywords:
Aggrecanase
Strain (injury)
Meniscus
The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs), enzymes that play central roles in the degradation of extracellular matrix components. The balance between MMPs and TIMPs is important in the maintenance of tissues, and its disruption affects tissue homoeostasis. Four related TIMPs (TIMP-1 to TIMP-4) can each form a complex with MMPs in a 1:1 stoichiometry with high affinity, but their inhibitory activities towards different MMPs are not particularly selective. The three-dimensional structures of TIMP-MMP complexes reveal that TIMPs have an extended ridge structure that slots into the active site of MMPs. Mutation of three separate residues in the ridge, at positions 2, 4 and 68 in the amino acid sequence of the N-terminal inhibitory domain of TIMP-1 (N-TIMP-1), separately and in combination has produced N-TIMP-1 variants with higher binding affinity and specificity for individual MMPs. TIMP-3 is unique in that it inhibits not only MMPs, but also several ADAM (a disintegrin and metalloproteinase) and ADAMTS (ADAM with thrombospondin motifs) metalloproteinases. Inhibition of the latter groups of metalloproteinases, as exemplified with ADAMTS-4 (aggrecanase 1), requires additional structural elements in TIMP-3 that have not yet been identified. Knowledge of the structural basis of the inhibitory action of TIMPs will facilitate the design of selective TIMP variants for investigating the biological roles of specific MMPs and for developing therapeutic interventions for MMP-associated diseases.
Aggrecanase
ADAMTS
Matrix metalloproteinase inhibitor
Cite
Citations (90)
The loss of aggrecan from cartilage that occurs during normal turnover and joint pathology involves the proteolytic actions of matrix metalloproteinases (MMPs) and "aggrecanase". This definitive statement is tempered, however, by not knowing precisely which members of the MMP family are involved, and not knowing the molecular identity of aggrecanase. Since its discovery in 1991, over 120 papers and conference reports have described the catalytic actions and expression of the putative aggrecanase in animal models, in vitro systems and human disease. Modulation of aggrecanase expression by cytokines and retinoate has been examined and studies exploring the relationship between aggrecanase and MMP activities in cartilage are ongoing. Many of these studies have been facilitated by the development of novel antibodies and new substrates. This chapter will review the relatively short history of aggrecanase and its role in cartilage proteoglycan degradation.
Aggrecanase
Aggrecan
Cite
Citations (3)
Aggrecan degradation is an important factor in the erosion of articular cartilage in arthritis. Aggrecanase is a newly cloned enzyme which degrades the core protein of aggrecan between the Glu 373 and Ala 374, a site different from the matrix metalloproteinases cleavage site, Asn 341～Phe 342. The discovery of aggrecanase and searching for its inhibitors will accelerate the development of therapeutic agents for arthritis.
Aggrecanase
Aggrecan
Cleavage (geology)
Cite
Citations (1)
Aggrecan
Aggrecanase
Arthropathy
Cite
Citations (10)
Abstract Aggrecanases are key matrix-degrading enzymes that act by cleaving aggrecan at the Glu373-Ala374 site. While these fragments have been detected in osteoarthritis (OA) and rheumatoid arthritis (RA) cartilage and synovial fluid, no information is available on the regulation or expression of the two key aggrecanases (aggrecanase-1 and aggrecanase-2) in synovial tissue (ST) or fibroblast-like synoviocytes (FLS). The aggrecanase-1 gene was constitutively expressed by both RA and OA FLS. Real-time PCR demonstrated that TGF-β significantly increased aggrecanase-1 gene expression in FLS. Aggrecanase-1 induction peaked after 24 h of TGF-β stimulation. The expression of aggrecanase-1 mRNA was significantly greater in RA ST than in OA or nonarthritis ST. Aggrecanase-2 mRNA and protein were constitutively produced by nonarthritis, OA, and RA FLS but were not increased by IL-1, TNF-α, or TGF-β. Furthermore, OA, RA, and nonarthritis ST contained similar amounts of immunoreactive aggrecanase-2. The major form of the aggrecanase-2 enzyme was 70 kDa in nonarthritis ST, whereas a processed 53-kDa form was abundant in RA ST. Therefore, aggrecanase-1 and -2 are differentially regulated in FLS. Both are constitutively expressed, but aggrecanase-1 is induced by cytokines, especially TGF-β. In contrast, aggrecanase-2 protein may be regulated by a post-translational mechanism in OA and RA ST. Synovial and FLS production of aggrecanase can contribute to cartilage degradation in RA and OA.
Aggrecanase
Aggrecan
Cite
Citations (167)
The importance of aggrecanase versus matrix metalloproteinase (MMP) enzymic activities in the degradation of aggrecan in normal and osteoarthritic (OA) articular cartilage in vitro was studied in order to further our understanding of the potential role of these two enzyme activities in aggrecan catabolism during the pathogenesis of cartilage degeneration. Porcine and bovine articular cartilage was maintained in explant culture for up to 20 days in the presence or absence of the catabolic stimuli retinoic acid, interleukin-1 or tumour necrosis factor-α. Release of proteoglycan from cartilage was measured as glycosaminoglycan (GAG) release using a colorimetric assay. Analysis of proteoglycan degradation products, both released into culture media and retained within the cartilage matrix, was performed by Western blotting using antibodies specific for the N- and C-terminal neoepitopes generated by aggrecanase- and MMP-related catabolism of the interglobular domain of the aggrecan core protein (IGD). In addition, studies determining the mRNA expression for MMP-3 and MMP-13 in these same cultures were undertaken. These analyses indicated that all three catabolic agents stimulated the release of > 80% of the GAG from the articular cartilage over 4 days. The degree of GAG release corresponded to an increase in aggrecanase-generated aggrecan catabolites released into the media and retained within the cartilage. Importantly, there was no evidence for the release of MMP-generated aggrecan metabolites into the medium, nor the accumulation of MMP-generated catabolites within the tissue in these same cultures. Expression of the mRNAs for two MMPs known to be capable of degrading the aggrecan IGD, MMP-3 and MMP-13, was detected. However, increased expression of these MMPs was not correlated with aggrecan degradation. Analyses using porcine cartilage, cultured with or without catabolic stimulation for 12 h to 20 days, indicated that primary cleavage of the IGD by aggrecanase was responsible for release of aggrecan metabolites at both the early and late time points of culture. Cultures of late-stage OA human articular cartilage samples indicated that aggrecanase activity was upregulated in the absence of catabolic stimulation when compared with normal porcine or bovine cartilage. In addition, even in this late-stage degenerate cartilage, aggrecanase and not MMP activity was responsible for the release of the majority of aggrecan from the cartilage. This study demonstrates that the release of aggrecan from both normal and OA cartilage in response to catabolic stimulation in vitro involves a primary cleavage by aggrecanase and not MMPs.
Aggrecanase
Aggrecan
Catabolism
Type II collagen
Cite
Citations (96)
Loss of aggrecan from articular cartilage is an early and critical event in the pathogenesis of osteoarthritis (OA) and is enzymatically mediated by aggrecanase activity. Since the discovery of aggrecanase-1 (ADAMTS-4) and aggrecanase-2 (ADAMTS-5), both members of the "a disintegrin and metalloproteinase with thrombospondin motif" family of proteinases, other members of the family have been reported to have aggrecanase activity, as currently defined, including ADAMTS-1, -8, -9, -15 and -16. Understanding whether these other ADAMTS members are in fact genuine in vivo aggrecanases will be important for the development of therapeutic agents that aim to block aggrecan degradation. The goal of this review is to look at the current definition of "aggrecanase activity", and define its strengths, weaknesses and suitability for determining which ADAMTS, are aggrecanases that participate in aggrecan catabolism in OA. In addition, we propose a more comprehensive definition of aggrecanase activity, based on 6 criteria that encompass both biochemical and biological characteristics of the endogenous aggrecanase activity detected in vitro and in vivo. Finally, using these criteria, we propose which ADAMTSs should be classified as aggrecanases and therefore be considered as drug targets for the development of chondroprotective OA treatments.
Aggrecanase
ADAMTS
Aggrecan
Cite
Citations (36)
The release of aggrecan catabolites from cartilage is an early event in the pathogenesis of degenerative joint diseases. The enzymes involved in this process are unknown, controversial, and the subject of intense investigation. In this paper we have utilized a recombinant substrate containing the interglobular domain (IGD) of aggrecan to study specifically aggrecanaseversus matrix metalloproteinase (MMP) catabolism in this domain of aggrecan. Our studies have shown that (i) there are species differences in the expression of latent versus active MMP activity on the aggrecan IGD; (ii) interleukin-1α exposure induces both aggrecanase and MMP activities, whereas retinoic acid induces only aggrecanase activity and inhibits the MMP activity on the aggrecan IGD; (iii) activators of latent MMP activity (p-aminophenylmercuric acetate and trypsin) significantly reduce aggrecanase activity; (iv) the time course of the appearance of aggrecanase versus the MMP catabolism of aggrecan IGD differs; (v) aggrecanase is a protease with metalloprotease characteristics; however (vi) the physiological (tissue) inhibitors of MMPs show weak inhibition (TIMP-1) or no inhibition (TIMP-2) of aggrecanase activity. Collectively, these studies show that aggrecanase and MMP catabolism of the aggrecan IGD are independent and uncoupled.
Aggrecanase
Aggrecan
Immunoglobulin D
Proteolysis
Catabolism
Cite
Citations (64)
Erosion of cartilage is a major feature of joint diseases, i.e., osteoarthritis and rheumatoid arthritis, which leads with time to a loss of joint function. Proteolytic cleavage of the aggrecan core protein is a key event in the progress of these joint diseases. Aggrecan degradation has been believed to be mediated by a putative proteinase, aggrecanase. We identified aggrecanase activity in conditioned medium from explant culture of bovine nasal cartilage stimulated by retinoic acid. The activity was partially purified more than 10,000-fold. The enzyme cleaves at the aggrecanase site (Glu(373)-Ala(374)) but not at the MMP site (Asn(341)-Phe(342)) in the interglobular domain of the aggrecan. It also cleaves at Glu(1971)-Leu(1972), which is located in the gap region in the chondroitin sulfate attachment region prior to the aggrecanase site. The enzyme is a typical Ca(2+)-dependent metalloproteinase with a unique salt-dependency and is inhibited by several hydroxamate-based inhibitors for matrix metalloproteinases. Heparin and chondroitin sulfate inhibited the enzyme in a dose-dependent manner, suggesting that the large carbohydorate in aggrecan is important for substrate recognition by aggrecanase.
Aggrecanase
Aggrecan
Cite
Citations (57)
Aggrecanase
Cleavage (geology)
Aggrecan
Proteolysis
Cite
Citations (19)