The ADAMTS metalloproteinases

Elucidating the function of non catalytic domains of collagenases and aggrecanases

Metalloproteinases that degrade extracellular matrix molecules play important roles in development and progression of various diseases. Among them, collagenases are unique as they have an ability to degrade triple helical interstitial collagens into 3/4 and 1/4 fragments, a crucial step for collagenolysis in the tissue. Collagenases, consisting of a catalytic domain and a hemopexin domain, requires both domains for collagenolysis. The enzymes unwind triple helical collagen before they hydrolyze the peptide bonds. Aggrecanases are also multidomain metalloproteinases belonging to the ADAMTS family, and the noncatalytic ancillary domains also play an important role in recognition of aggrecan and their activities. Attenuation of collagenase and aggrecanase activities will be achieved by inhibitors or antibodies that interact directly with those noncatalytic ancillary domains (exosite inhibitors). Such molecules will be attractive for therapy as they will be highly selective because they are based on the unique mechanism of each proteinase.

Pathophysiology of the human intervertebral disc

Intervertebral disc degeneration is a common invalidating disorder that can affect the musculoskeletal apparatus in both younger and older ages. The chief component of the intervertebral disc is the highly organized extracellular matrix; maintenance of its organization is essential for correct spinal mechanics. The matrix components, mainly proteoglycans and collagens, undergo a slow and continuous cell-mediated turnover process that enables disc cells to adapt their environment to external stimuli. Cellular senescence and a history of chronic abnormal loading can upset this balance, leading to progressive tissue failure that results in disc degeneration. Although biological treatment approaches to disc repair are still far to come, advances in our understanding of disc biochemistry and in defining the role of genetic inheritance have provided a starting point for developing new concepts in the diagnosis, therapy and prevention of disc degeneration.

Functional differences of the catalytic and non-catalytic domains in human ADAMTS-4 and ADAMTS-5 in aggrecanolytic activity

ADAMTS-4 (aggrecanase-1) and ADAMTS-5 (aggrecanase-2) are multidomain metalloproteinases belonging to the ADAMTS family. We have previously reported that human ADAMTS-5 has much higher aggrecanolytic activity than human ADAMTS-4. To investigate the different proteolytic activity of the two enzymes, we generated a series of chimeras by exchanging various non-catalytic domains of the two proteinases. We found that the catalytic domain of ADAMTS-5 has higher intrinsic catalytic ability than that of ADAMTS-4. The studies also demonstrated that the non-catalytic domains of ADAMTS-5 are more effective modifiers than those of ADAMTS-4, making both catalytic domains more active against aggrecan, an Escherichia coli-expressed interglobular domain of aggrecan and fibromodulin. Addition of the C-terminal thrombospondin type I motif of ADAMTS-5 to the C terminus of ADAMTS-4 increased the activity of ADAMTS-4 against aggrecan and fibromodulin severalfold. In contrast to previous reports (Kashiwagi, M., Enghild, J. J., Gendron, C., Hughes, C., Caterson, B., Itoh, Y., and Nagase, H. (2004) J. Biol. Chem. 279, 10109-10119 and Gao, G., Plaas, A., Thompson, V. P., Jin, S., Zuo, F., and Sandy, J. D. (2004) J. Biol. Chem. 279, 10042-10051), our detailed investigation of the role of the C-terminal spacer domain of ADAMTS-4 indicated that full-length ADAMTS-4 is approximately 20-times more active against aggrecan than its spacer domain deletion mutant, even at the Glu373-Ala374 site of the interglobular domain. This discrepancy is most likely due to selective inhibition of full-length ADAMTS-4 by heparin, particularly for cleavage at the Glu373-Ala374 bond. However, removal of the spacer domain from ADAMTS-4 greatly enhanced more general proteolytic activity against non-aggrecan substrates, e.g. E. coli-expressed interglobular domain, fibromodulin, and carboxymethylated transferrin.

Multimodal signaling by the ADAMTSs (a disintegrin and metalloproteinase with thrombospondin motifs) promotes neurite extension

Aggregating proteoglycans (PG) bearing chondroitin sulfate (CS) side chains associate with hyaluronan and various secreted proteins to form a complex of extracellular matrix (ECM) that inhibits neural plasticity in the central nervous system (CNS). Chondroitinase treatment depletes PGs of their CS side chains and enhances neurite extension. Increasing evidence from in vivo models indicates that proteolytic cleavage of the PG core protein by members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family of glutamyl-endopeptidases also promotes neural plasticity. The purpose of this study was to determine whether proteolytic action of the ADAMTSs influences neurite outgrowth in cultured neurons. Transfection of primary rat neurons with ADAMTS4 cDNA induced longer neurites, whether the neurons were grown on a monolayer of astrocytes that secrete inhibitory PGs or on laminin/poly-L-lysine substrate alone. Similar results were found when neurons were transfected with a construct encoding a proteolytically inactive, point mutant of ADAMTS4. Addition of recombinant ADAMTS4 or ADAMTS5 protein to immature neuronal cultures also enhanced neurite extension in a dose-dependent manner, an effect demonstrated to be dependent on the activation of MAP ERK1/2 kinase. These results suggest that ADAMTS4 enhances neurite outgrowth via a mechanism that does not require proteolysis but is dependent on activation of the MAP kinase cascade. Thus a model to illustrate multimodal ADAMTS activity would entail proteolysis of CS-bearing PGs to create a loosened matrix environment more favorable for neurite outgrowth, and enhanced neurite outgrowth directly stimulated by ADAMTS signaling at the cell surface.

The roles of proteolytic enzymes in the development of tumour-induced bone disease in breast and prostate cancer

Tumour-induced bone disease is a common clinical feature of advanced breast and prostate cancer and is associated with considerable morbidity for the affected patients. Our understanding of the molecular mechanisms underlying the development of bone metastases is incomplete, but proteolytic enzymes are implicated in a number of processes involved in both bone metastasis and in normal bone turnover, including matrix degradation, cell migration, angiogenesis, tumour promotion and growth factor activation. Malignant as well as non-malignant cells in the primary and secondary sites express these enzymes, the activity of which may be regulated by soluble factors, cell- or matrix-associated components, as well as a number of cell signalling pathways. A number of secreted and cell surface-associated proteolytic enzymes are implicated in tumour-induced bone disease, including the matrix metalloproteinases, lysosomal cysteine proteinases and plasminogen activators. This review will introduce the role of proteolytic enzymes in normal bone turnover and give an overview of the studies in which their involvement and regulation in the development of bone metastases in breast and prostate cancer has been described. The results from trials involving protease inhibitors in clinical development will also be briefly discussed.

Epigenetic identification of ADAMTS18 as a novel 16q23.1 tumor suppressor frequently silenced in esophageal, nasopharyngeal and multiple other carcinomas

Tumor suppressor genes (TSGs) often locate at chromosomal regions with frequent deletions in tumors. Loss of 16q23 occurs frequently in multiple tumors, indicating the presence of critical TSGs at this locus, such as the well-studied WWOX. Herein, we found that ADAMTS18, located next to WWOX, was significantly downregulated in multiple carcinoma cell lines. No deletion of ADAMTS18 was detected with multiplex differential DNA-PCR or high-resolution 1-Mb array-based comparative genomic hybridization (CGH) analysis. Instead, methylation of the ADAMTS18 promoter CpG Island was frequently detected with methylation-specific PCR and bisulfite genome sequencing in multiple carcinoma cell lines and primary carcinomas, but not in any nontumor cell line and normal epithelial tissue. Both pharmacological and genetic demethylation dramatically induced the ADAMTS18 expression, indicating that CpG methylation directly contributes to the tumor-specific silencing of ADAMTS18. Ectopic ADAMTS18 expression led to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells lacking the expression. Thus, through functional epigenetics, we identified ADAMTS18 as a novel functional tumor suppressor, being frequently inactivated epigenetically in multiple carcinomas.

Aggrecanases and aggrecanase-generated fragments in the human intervertebral disc at early and advanced stages of disc degeneration

STUDY DESIGN

A comparative study of aggrecanases and aggrecan fragmentation profile in the human intervertebral disc at early and advanced stages of disc degeneration.

OBJECTIVE

To determine differences in the content of the aggrecanases and the profile of aggrecan fragmentation in early and advanced stages of disc degeneration using cadaveric human intervertebral discs.

SUMMARY OF BACKGROUND DATA

Aggrecanases and aggrecanase-generated aggrecan fragments have been found in human degenerated discs. However, the association between the grade of disc degeneration and the content of the aggrecanases and the profile of aggrecan fragments has not been well studied.

METHODS

A total of 108 cadaveric donor spines were assessed by MRI T2 imaging and graded based on the Thompson scale. Twelve donor spines (average age, 63 years), each specifically exhibiting 2 different stages (Grade 2 and Grade 4) of disc degeneration at different disc levels, were included in this study. After harvesting the preselected discs, tissue samples were obtained from the center of the nucleus pulposus (NP) and the middle zone of the anulus fibrosus (AF). The amount of the aggrecanases, specifically ADAMTS-4 and ADAMTS-5, and the pattern of aggrecan fragmentation in the isolated tissues were assessed by western blot using specific antibodies.

RESULTS

In both NP and the AF tissues, the amount of ADAMTS-4 detected was higher in disc tissues with a higher level of degeneration (Grade 4) than in Grade 2 disc tissues with a lower level of degeneration. However, the amount of ADAMTS-5 detected did not differ between the 2 disc tissue grades. The aggrecan fragmentation analysis of these samples demonstrated the presence of aggrecanase-mediated fragmentation in both groups; however, there was no apparent difference in the aggrecan fragmentation profile between discs at early and advanced stages of disc degeneration.

CONCLUSION

Aggrecanases are involved in aggrecanolysis at both the early and advanced stages of disc degeneration. The aggrecan fragmentation profile analysis demonstrates the involvement of aggrecanases, as well as that of matrix metalloproteinases and/or cathepsins, during disc degeneration.

ADAMTSL3/punctin-2, a gene frequently mutated in colorectal tumors, is widely expressed in normal and malignant epithelial cells, vascular endothelial cells and other cell types, and its mRNA is reduced in colon cancer

ADAMTSL3/punctin-2 is a secreted glycoprotein that resembles the ADAMTS proteases. Recently, identification of frequent ADAMTSL3 mutations in colorectal cancer suggested it might have a regulatory role in cellular homeostasis in colorectal epithelium or in pathways to colorectal malignancy. Here, we used in situ hybridization to validate ADAMTSL3 antibodies for IHC of a variety of normal and malignant tissues, including colon cancer. Quantitative real-time PCR (RTQ-PCR) was used to compare mRNA expression levels in colon carcinoma (n = 10) and adjacent normal colon. ADAMTSL3 is expressed in epithelial cells of the colon, fallopian tube, skin, breast, prostate, epididymis, liver, pancreatic islets and bile ducts, as well as by vascular endothelial cells, smooth muscle cells, fibroblasts, cortical and ganglionic neurons and cardiac myocytes. Malignant epithelial cells in colon cancer, as well as breast, prostate, renal and skin tumors expressed ADAMTSL3. Normal colon showed stronger immunostaining of surface than basal crypt epithelium and staining of a variety of cells within the lamina propria and submucosa. Colon carcinomas demonstrated weaker staining in tumor cells than normal colon epithelium and weak stromal staining. RTQ-PCR comparison of ADAMTSL3 mRNA in colon carcinoma and adjacent normal colon demonstrated a statistically significant reduction in the tumors, possibly reflecting their decreased stromal content and lack of complete differentiation of tumor samples. The major findings of these studies are that ADAMTSL3 is expressed in numerous tissues, suggesting a broader regulatory role than in colorectal epithelium alone, and that colorectal cancer has both structural mutations as well as decreased expression of ADAMTSL3.

Emerging roles of proteases in tumour suppression

Proteases have long been associated with cancer progression because of their ability to degrade extracellular matrices, which facilitates invasion and metastasis. However, recent studies have shown that these enzymes target a diversity of substrates and favour all steps of tumour evolution. Unexpectedly, the post-trial studies have also revealed proteases with tumour-suppressive effects. These effects are associated with more than 30 different enzymes that belong to three distinct protease classes. What are the clinical implications of these findings?

VEGF induces Tie2 shedding via a phosphoinositide 3-kinase/Akt dependent pathway to modulate Tie2 signaling

OBJECTIVE

Tie2 and its ligands, the angiopoietins (Ang), are required for embryonic and postnatal angiogenesis. Previous studies have demonstrated that Tie2 is proteolytically cleaved, resulting in the production of a 75-kDa soluble receptor fragment (sTie2). We investigated mechanisms responsible for Tie2 shedding and its effects on Tie2 signaling and endothelial cellular responses.

METHODS AND RESULTS

sTie2 bound both Ang1 and Ang2 and inhibited angiopoietin-mediated Tie2 phosphorylation and antiapoptosis. In human umbilical vein endothelial cells, Tie2 shedding was both constitutive and induced by treatment with PMA or vascular endothelial growth factor (VEGF). Constitutive and VEGF-inducible Tie2 shedding were mediated by PI3K/Akt and p38 MAPK. Tie2 shedding was blocked by pharmacological inhibitors of either PI3K or Akt as well as by overexpression of the lipid phosphatase PTEN. In contrast, sTie2 shedding was enhanced by overexpression of either dominant negative PTEN, which increased Akt phosphorylation, or constitutively active, myristoylated Akt.

CONCLUSIONS

These findings demonstrate that VEGF regulates angiopoietin-Tie2 signaling by inducing proteolytic cleavage and shedding of Tie2 via a novel PI3K/Akt-dependent pathway. These results suggest a previously unrecognized mechanism by which VEGF may inhibit vascular stabilization to promote angiogenesis and vascular remodeling.

Matrix metalloproteinases in neuromuscular disease

Matrix metalloproteinases (MMPs), a family of zinc-dependent endoproteinases, are effector molecules in the breakdown of the blood-brain and blood-nerve barrier, and promote neural tissue invasion by leukocytes in inflammatory diseases of the central and peripheral nervous systems. Moreover, MMPs play an important role in synaptic remodeling, neuronal regeneration, and remyelination. Recent work concerning MMPs in patients with neuropathy, myopathy, spinal cord injury, and amyotrophic lateral sclerosis (ALS), and in corresponding animal models, is discussed in this review.

The ADAMTS12 metalloproteinase exhibits anti-tumorigenic properties through modulation of the Ras-dependent ERK signalling pathway

Members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family of proteolytic enzymes are implicated in a variety of physiological processes, such as collagen maturation, organogenesis, angiogenesis, reproduction and inflammation. Moreover, deficiency or overexpression of certain ADAMTS proteins is directly involved in serious human diseases, including cancer. However, the functional roles of other family members, such as ADAMTS12, remain unknown. Here, by using different in vitro and in vivo approaches, we have evaluated the possible role of ADAMTS12 in the development and progression of cancer. First, we show that expression of ADAMTS12 in Madin-Darby canine kidney (MDCK) cells prevents the tumorigenic effects of hepatocyte growth factor (HGF) by blocking the activation of the Ras-MAPK signalling pathway and that this regulation involves the thrombospondin domains of the metalloproteinase. We also show that addition of recombinant human ADAMTS12 to bovine aortic endothelial cells (BAE-1 cells) abolishes their ability to form tubules upon stimulation with vascular endothelial growth factor (VEGF). Additionally, tumours induced in immunodeficient SCID mice injected with A549 cells overexpressing ADAMTS12 show a remarkable growth deficiency in comparison with tumours formed in animals injected with parental A549 cells. Overall, our data suggest that ADAMTS12 confers tumour-protective functions upon cells that produce this proteolytic enzyme.

Screening of potential a disintegrin and metalloproteinase with thrombospondin motifs-4 inhibitors using a collagen model fluorescence resonance energy transfer substrate

The major components of the cartilage extracellular matrix are type II collagen and aggrecan. Type II collagen provides cartilage with its tensile strength, whereas the water-binding capacity of aggrecan provides compressibility and elasticity. Aggrecan breakdown leads to an increase in proteolytic susceptibility of articular collagen; hence, aggrecan may also have a protective effect on type II collagen. Given their role in aggrecan degradation and differing substrate specificity profiles, the pursuit of inhibitors for both aggrecanase 1 (a disintegrin and metalloproteinase with thrombospondin motifs-4 [ADAMTS-4]) and aggrecanase 2 (ADAMTS-5) is desirable. We previously described collagen model fluorescence resonance energy transfer (FRET) substrates for aggrecan-degrading members of the ADAMTS family. These FRET substrate assays are also fully compatible with multiwell formats. In the current study, a collagen model FRET substrate was examined for inhibitor screening of ADAMTS-4. ADAMTS-4 was screened against a small compound library (n=960) with known pharmacological activity. Five compounds that inhibited ADAMTS-4>60% at a concentration of 1muM were identified. A secondary screen using reversed-phase high-performance liquid chromatography (RP-HPLC) was developed and performed for verification of the five potential inhibitors. Ultimately, piceatannol was confirmed as a novel inhibitor of ADAMTS-4, with an IC(50) value of 1muM. Because the collagen model FRET substrates have distinct conformational features that may interact with protease secondary substrate sites (exosites), nonactive site-binding inhibitors can be identified via this approach. Selective inhibitors for ADAMTS-4 would allow a more definitive evaluation of this protease in osteoarthritis and also represent a potential next generation in metalloproteinase therapeutics.

Emerging roles of ADAM and ADAMTS metalloproteinases in cancer

A disintegrin and metalloproteinases (ADAMs) are a recently discovered family of proteins that share the metalloproteinase domain with matrix metalloproteinases (MMPs). Among this family, structural features distinguish the membrane-anchored ADAMs and the secreted ADAMs with thrombospondin motifs referred to as ADAMTSs. By acting on a large panel of membrane-associated and extracellular substrates, they control several cell functions such as adhesion, fusion, migration and proliferation. The current review addresses the contribution of these proteinases in the positive and negative regulation of cancer progression as mainly mediated by the regulation of growth factor activities and integrin functions.

Matrix metalloproteinase inhibitors as therapy for inflammatory and vascular diseases

Matrix metalloproteinases (MMPs) have outgrown the field of extracellular-matrix biology and have progressed towards being important regulatory molecules in cancer and inflammation. This rise in status was accompanied by the development of various classes of inhibitors. Although clinical trials with synthetic inhibitors for the treatment of cancer were disappointing, recent data indicate that the use of selective inhibitors might lead to new therapies for acute and chronic inflammatory and vascular diseases. In this Review, we compare the major classes of MMP inhibitors and advocate that future drug discovery should be based on crucial insights into the differential roles of specific MMPs in pathophysiology obtained with animal models, including knockout studies.

Peptides derived from type I thrombospondin repeat-containing proteins of the CCN family inhibit proliferation and migration of endothelial cells

Angiogenesis, or neovascularization, is tightly orchestrated by endogenous regulators that promote or inhibit the process. The fine-tuning of these pro- and anti-angiogenic elements (the angiogenic balance) helps establish the homeostasis in tissues, and any aberration leads to pathologic conditions. The type I thrombospondin repeats are a family of protein structural elements involved in the control of angiogenesis, and some proteins containing these repeats have been identified as negative regulators of angiogenesis. Here we identify a set of 11 novel, anti-angiogenic 18-20-amino acid peptides that are derived from proteins that belong to the CCN protein family and contain type I thrombospondin motifs. We have named these peptides spondinstatin-1, cyrostatin, connectostatin, nephroblastostatin, wispostatin-2, wispostatin-3, netrinstatin-5C, netrinstatin-5D, adamtsostatin-like-4, fibulostatin-6.1, and complestatin-C6 to reflect their origin. We have shown that these peptides inhibit proliferation and migration of human umbilical vein endothelial cells in vitro. By conducting a clustering analysis of the amino acid sequences using sequence similarity criteria and of the experimental results using a hierarchical clustering algorithm, we have demonstrated that there is an underlying correlation between the sequence and activity of the identified peptides. This combination of experimental and computational approaches introduces a novel systematic framework for studying peptide activity, identifying novel peptides with anti-angiogenic activity, and designing mimetic peptides with tailored properties.

Brevican and phosphacan expression and localization following transient middle cerebral artery occlusion in the rat

The ECM (extracellular matrix) is a complex molecular framework that provides physical support to cells and tissues, while also providing signals for cell growth, migration, differentiation and survival. The ECM of the CNS (central nervous system) is unusual in that it is rich in CSPGs (chondroitin sulfate proteoglycans), hyaluronan and tenascins. The CSPGs are widely expressed throughout the developing and adult CNS and have a role in guiding or limiting neurite outgrowth and cell migration. Alterations in the synthesis or breakdown of the ECM may contribute to disease processes. Here, we examine changes in the brain-specific CSPGs, brevican and phosphacan, following transient middle cerebral artery occlusion, a model of stroke in the rat. We have investigated their expression at various time points as well as their spatial relationship with ADAMTS-4 (adisintegrin and metalloprotease with thrombospondin motifs 4). The co-localization of ADAMTS or its activity may indicate a functional role for this matrix–protease pair in degeneration/regeneration processes that occur in stroke.

Hyaluronidase and collagenase inhibitory activities of the herbal formulation Triphala guggulu

Myrrh (guggulu) oleoresin from the Commiphora mukul tree is an important component of antiarthritic drugs in Ayurvedic medicine. Clinical data suggest that elevated levels of hyaluronidase and collagenase type 2 enzymes contribute significantly to cartilage degradation. Triphala guggulu (TG) is a guggulu-based formulation used for the treatment of arthritis. We assessed the chondroprotective potential of TG by examining its effects on the activities of pure hyaluronidase and collagenase type 2 enzymes. Triphala shodith guggulu (TSG), an intermediate in the production of TG, was also examined. A spectrophotometric method was used to assay Hyaluronidase activity, and to detect potential Hyaluronidase inhibitors. Aqueous and hydro-alcoholic extracts of TSG showed weak but dose-dependent inhibition of hyaluronidase activity. In contrast, the TG formulation was 50 times more potent than the TSG extract with respect to hyaluronidase inhibitory activity. A validated X-ray film-based assay was used to measure the gelatinase activity of pure collagenase type 2. Hydro-alcoholic extracts of the TG formulation were 4 times more potent than TSG with respect to collagenase inhibitory activity. Components of Triphala were also evaluated for their inhibitory activities on hyaluronidase and collagenase. This is the first report to show that the T2 component of Triphala (T.chebula) is a highly potent hyaluronidase and collagenase inhibitor. Thus, the TG formulation inhibits two major enzymes that can degrade cartilage matrix. Our study provides the first in vitro preclinical evidence of the chondroprotective properties of TG.

Tissue inhibitor of metalloproteinase-2 (TIMP-2) regulates myogenesis and beta1 integrin expression in vitro

Myogenesis in vitro involves myoblast cell cycle arrest, migration, and fusion to form multinucleated myotubes. Extracellular matrix (ECM) integrity during these processes is maintained by the opposing actions of matrix metalloproteinase (MMP) proteases and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs). Here, we report that TIMP-2, MMP-2, and MT1-MMP are differentially expressed during mouse myoblast differentiation in vitro. A specific role for TIMP-2 in myogenesis is demonstrated by altered TIMP-2(-/-) myotube formation. When differentiated in horse serum-containing medium, TIMP-2(-/-) myotubes are larger than wild-type myotubes. In contrast, when serum-free medium is used, TIMP-2(-/-) myotubes are smaller than wild-type myotubes. Regardless of culture condition, myotube size is directly correlated with MMP activity and inversely correlated with beta1 integrin expression. Treatment with recombinant TIMP-2 rescues reduced TIMP-2(-/-) myotube size and induces increased MMP-9 activation and decreased beta1 integrin expression. Treatment with either MMP-2 or MMP-9 similarly rescues reduced myotube size, but has no effect on beta1 integrin expression. These data suggest a specific regulatory relationship between TIMP-2 and beta1 integrin during myogenesis. Elucidating the role of TIMP-2 in myogenesis in vitro may lead to new therapeutic options for the use of TIMP-2 in myopathies and muscular dystrophies in vivo.

Expression and significance of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1 in an animal model of renal interstitial fibrosis induced by unilateral ureteral obstruction

To evaluate the pathological roles of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1 in rat renal interstitial fibrosis, we examined the expression, localization and effect on growth of ADAMTS-1 in a normal rat kidney cell line (NRK-49F). Increased ADAMTS-1 mRNA expression was observed in the kidney by in situ hybridization after induction of unilateral ureteral obstruction (UUO) in male Wistar rats, the mRNA was localized in the renal tubular epithelial cells in the outer stripe of the outer medulla in the UUO kidney. On the other hand, no positive signals were observed in the sham-operated-kidney. Western-blot analysis of stable human embryonic kidney 293 (HEK293) transformant cells expressing rat ADAMTS-1 containing the V5 tag using anti-V5 tag monoclonal antibody revealed the presence of two post-translationally processed bands in the cells: an 87-kDa band with a metalloproteinase motif and 65-kDa band with a thrombospondin motifs. On the other hand, secretion of the 65-kDa protein into the culture supernatants from the transformant cells was confirmed. Treatment with the culture supernatant of the transformant cells potently reduced the uptake of 3H-thymidine in the NRK-49F cells, no such inhibitory effect was observed with the culture medium of the HEK293 cells. These results suggest that the UUO-induced expression of ADAMTS-1 in the rat renal tubular epithelial cells may actively contribute to the inhibition of DNA synthesis in the renal interstitial fibroblasts via the 65-kDa moiety with thrombospondin motifs.

Bone morphogenetic protein-1 (BMP-1) cleaves human proapolipoprotein A1 and regulates its activation for lipid binding

Apolipoprotein A1 (apo A1), the major protein of high-density lipoprotein, is secreted as a proprotein and then cleaved by an uncharacterized metalloproteinase. Here this enzyme is identified as C-terminal procollagen endoproteinase/bone morphogenetic protein-1 (BMP-1). Studies with recombinant BMP-1, BMP-1 antibody, and BMP-1 siRNA establish this proteinase as the major or only apo A1-converting activity secreted by human liver-derived (HepG2) cells and CHO cells stably expressing human apo A1. BMP-1 stimulates the conversion of newly secreted proapo A1 to its phospholipid- (PL-) binding form. In this way it promotes formation of functional HDL and reverse cholesterol transport, while inhibiting filtration and clearance of uncleaved proprotein. Alpha2-macroglobulin, a protease inhibitor secreted as part of the innate immune response, inhibits BMP-1 activity and blocks the maturation of proapo A1. The decrease in circulating apo A1 levels that is characteristic of the response to inflammation and infection may be mediated, at least in part, via BMP-1 by this novel mechanism.

Unravelling the moulting degradome: new opportunities for chemotherapy?

Replacement of the nematode cuticle with a newly synthesized cuticle (a process known as moulting) occurs four times during larval development. Therefore, the key components of this essential developmental process represent attractive targets for new chemotherapeutic strategies. Recent advances in understanding the molecular genetics of nematode moulting should stimulate and facilitate development of novel drugs that target the essential molecules of the moulting cycle. In particular, we argue that further understanding of the moulting degradome and its key peptidase members offers an important opportunity for the development of novel antinematode agents.

FSH stimulates the expression of the ADAMTS-16 protease in mature human ovarian follicles

We report the characterization of full-length human ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs)-16, a novel member of the disintegrin and metalloproteinase with thrombospondin motifs (hence ADAMTS) family. ADAMTS-16 is highly expressed both in the kidney and in the ovary, where it is predominantly expressed in the parietal granulosa cells of pre-ovulatory follicles but only slightly expressed in cells of the cumulus oophorus. In fully differentiated luteinizing granulosa cells, follicle-stimulating hormone and forskolin induces expression of ADAMTS-16, suggesting that it is regulated via the cAMP pathway. Luteinizing hormone had a minor effect on the expression of ADAMTS-16. ADAMTS-16 is capable of cleaving alpha2-macroglobulin (MG), a common substrate for proteases, which is present at high concentrations in the follicular fluid of ovarian follicles. These studies provide the first evidence that ADAMTS-16 is an active protease and suggest a physiological role of ADAMTS-16 in ovarian follicles, at least during the pre-ovulatory phase.

Blocking aggrecanase cleavage in the aggrecan interglobular domain abrogates cartilage erosion and promotes cartilage repair

Aggrecan loss from cartilage in arthritis is mediated by aggrecanases. Aggrecanases cleave aggrecan preferentially in the chondroitin sulfate-2 (CS-2) domain and secondarily at the E(373) downward arrow(374)A bond in the interglobular domain (IGD). However, IGD cleavage may be more deleterious for cartilage biomechanics because it releases the entire CS-containing portion of aggrecan. Recent studies identifying aggrecanase-2 (ADAMTS-5) as the predominant aggrecanase in mouse cartilage have not distinguished aggrecanolysis in the IGD from aggrecanolysis in the CS-2 domain. We generated aggrecan knockin mice with a mutation that rendered only the IGD resistant to aggrecanases in order to assess the contribution of this specific cleavage to cartilage pathology. The knockin mice were viable and fertile. Aggrecanase cleavage in the aggrecan IGD was not detected in knockin mouse cartilage in situ nor following digestion with ADAMTS-5 or treatment of cartilage explant cultures with IL-1 alpha. Blocking cleavage in the IGD not only diminished aggrecan loss and cartilage erosion in surgically induced osteoarthritis and a model of inflammatory arthritis, but appeared to stimulate cartilage repair following acute inflammation. We conclude that blocking aggrecanolysis in the aggrecan IGD alone protects against cartilage erosion and may potentiate cartilage repair.

Anti-angiogenic peptides identified in thrombospondin type I domains

Thrombospondin 1, the prototypical protein of the thrombospondin protein family, is a potent endogenous inhibitor of angiogenesis. Although the effects of the thrombospondin 1 on neovascularization have been well studied, little is known about the anti-angiogenic potency of other proteins or peptide fragments derived from the proteins in this family. Here we identify a set of 18 novel, anti-angiogenic 17- to 20-amino acid peptides that are derived from proteins containing type I thrombospondin motifs. We have named these peptides adamtsostatin-4, adamtsostatin-16, adamtsostatin-18, cartilostatin-1, cartilostatin-2, fibulostatin-6.2, fibulostatin-6.3, papilostatin-1, papilostatin-2, properdistatin, scospondistatin, semastatin-5A.1, semastatin-5A.2, semastatin-5B, thrombostatin containing-1, thrombostatin contaning-3, thrombostatin contaning-6, and wispostatin-1 to reflect their origin. We further demonstrate that these peptides inhibit the proliferation and migration of human umbilical vein endothelial cells in vitro. The anti-proliferative and anti-migratory properties of the identified peptides may be important in maintaining angiogenic homeostasis in vivo and make these peptides suitable candidates for use as anti-angiogenic pharmaceutical agents in numerous therapeutic applications.

Prodomain-dependent tissue targeting of an ADAMTS protease controls cell migration in Caenorhabditis elegans

Members of the ADAMTS (a disintegrin and metalloprotease with thrombospondin motifs) family of secreted proteins play important roles in animal development and pathogenesis. However, the lack of in vivo models has hampered elucidation of the mechanisms by which these enzymes are recruited to specific target tissues and the timing of their activation during development. Using transgenic worms and primary cell cultures, here we show that MIG-17, an ADAMTS family protein required for gonadal leader cell migration in Caenorhabditis elegans, is recruited to the gonadal basement membrane in a prodomain-dependent manner. The activation of MIG-17 to control leader cell migration requires prodomain removal, which is suggested to occur autocatalytically in vitro. Although the prodomains of ADAMTS proteases have been implicated in maintaining enzymatic latency, polypeptide folding and secretion, our findings demonstrate that the prodomain has an unexpected function in tissue-specific targeting of MIG-17; this prodomain targeting function may be shared by other ADAMTSs including those in vertebrates.

Substrate-dependent inhibition kinetics of an active site-directed inhibitor of ADAMTS-4 (Aggrecanase 1)

ADAMTS-4 (aggrecanase-1) is implicated in the breakdown of articular cartilage and is an attractive target for therapeutic intervention in arthritis. Cleavage of the native substrate, aggrecan, occurs through exosite interactions and peptide sequence recognition. Although expected to be competitive with aggrecan, the hydroxamic acid, SC81956, demonstrated noncompetitive inhibition kinetics with a Ki of 23 nM. The IC50 of SC81956 did not change when aggrecan was varied from 12.8 to 200 nM (0.2-3.3 times the apparent aggrecan Km of 61 nM) but was shifted as expected for a competitive inhibitor when increasing levels of a low molecular weight peptide substrate were added to a fluorogenic peptide assay system. These observations are consistent with a model for aggrecan cleavage where substrate initially binds at an exosite, followed by binding of the appropriate peptide sequence at the active site. A peptide-competitive inhibitor could bind both free enzyme and initial substrate-enzyme exosite complex but would be excluded by the final Michaelis complex. Noncompetitive appearing kinetics for such inhibitors is predicted as long as the equilibrium between the two forms of enzyme-substrate complex significantly favors the initial exosite complex. In support, hydrolysis of a low molecular weight peptide substrate and its inhibition by SC81956 were unaffected by aggrecan concentrations substantially above the Km. These observations suggest that the apparent Km for aggrecan cleavage predominately reflects the exosite interaction. Consequently, the efficacy of active-site inhibitors of ADAMTS-4 will not be limited by competition with native substrate as predicted from the Km determined by traditional kinetic models.

TIMP-3 inhibition of ADAMTS-4 (Aggrecanase-1) is modulated by interactions between aggrecan and the C-terminal domain of ADAMTS-4

ADAMTS-4 (aggrecanase-1) is a glutamyl endopeptidase capable of generating catabolic fragments of aggrecan analogous to those released from articular cartilage during degenerative joint diseases such as osteoarthritis. Efficient aggrecanase activity requires the presence of sulfated glycosaminoglycans attached to the aggrecan core protein, implying the contribution of substrate recognition/binding site(s) to ADAMTS-4 activity. In this study, we developed a sensitive fluorescence resonance energy transfer peptide assay with a K(m) in the 10 microm range and utilized this assay to demonstrate that inhibition of full-length ADAMTS-4 by full-length TIMP-3 (a physiological inhibitor of metalloproteinases) is enhanced in the presence of aggrecan. Our data indicate that this interaction is mediated largely through the binding of glycosaminoglycans (specifically chondroitin 6-sulfate) of aggrecan to binding sites in the thrombospondin type 1 motif and spacer domains of ADAMTS-4 to form a complex with an improved binding affinity for TIMP-3 over free ADAMTS-4. The results of this study therefore indicate that the cartilage environment can modulate the function of enzyme-inhibitor systems and could have relevance for therapeutic approaches to aggrecanase modulation.

Proteolytic activities of human ADAMTS-5: comparative studies with ADAMTS-4

Aggrecanases have been characterized as proteinases that cleave the Glu373-Ala374 bond of the aggrecan core protein, and they are multidomain metalloproteinases belonging to the ADAMTS (adamalysin with thrombospondin type 1 motifs) family. The first aggrecanases discovered were ADAMTS-4 (aggrecanase 1) and ADAMTS-5 (aggrecanase 2). They contain a zinc catalytic domain followed by non-catalytic ancillary domains, including a disintegrin domain, a thrombospondin domain, a cysteine-rich domain, and a spacer domain. In the case of ADAMTS-5, a second thrombospondin domain follows the spacer domain. We previously reported that the non-catalytic domains of ADAMTS-4 influence both its extracellular matrix interaction and proteolytic abilities. Here we report the effects of these domains of ADAMTS-5 on the extracellular matrix interaction and proteolytic activities and compare them with those of ADAMTS-4. Although the spacer domain was critical for ADAMTS-4 localization in the matrix, the cysteine-rich domain influenced ADAMTS-5 localization. Similar to previous reports of other ADAMTS family members, very little proteolytic activity was detected with the ADAMTS-5 catalytic domain alone. The sequential inclusion of each carboxyl-terminal domain enhanced its activity against aggrecan, carboxymethylated transferrin, fibromodulin, decorin, biglycan, and fibronectin. Both ADAMTS-4 and -5 had a broad optimal activity at pH 7.0-9.5. Aggrecanolytic activities were sensitive to the NaCl concentration, but activities on non-aggrecan substrates, e.g. carboxymethylated transferrin, were not affected. Although ADAMTS-4 and ADAMTS-5 had similar general proteolytic activities, the aggrecanase activity of ADAMTS-5 was at least 1,000-fold greater than that of ADAMTS-4 under physiological conditions. Our studies suggest that ADAMTS-5 is a major aggrecanase in cartilage metabolism and pathology.

O-fucosylation of thrombospondin type 1 repeats in ADAMTS-like-1/punctin-1 regulates secretion: implications for the ADAMTS superfamily

The ADAMTS superfamily contains several metalloproteases (ADAMTS proteases) as well as ADAMTS-like molecules that lack proteolytic activity. Their common feature is the presence of one or more thrombospondin type-1 repeats (TSRs) within a characteristic modular organization. ADAMTS like-1/punctin-1 has four TSRs. Previously, O-fucosylation on Ser or Thr mediated by the endoplasmic reticulum-localized enzyme protein-O-fucosyltransferase 2 (POFUT2) was described for TSRs of thrombospondin-1, properdin, and F-spondin within the sequence Cys-Xaa(1)-Xaa(2)-(Ser/Thr)-Cys-Xaa-Xaa-Gly (where the fucosylated residue is underlined). On mass spectrometric analysis of tryptic peptides from recombinant secreted human punctin-1, the appropriate peptides from TSR2, TSR3, and TSR4 were found to bear either a fucose monosaccharide (TSR3, TSR4) or a fucose-glucose disaccharide (TSR2, TSR3, TSR4). Although mass spectral analysis did not unambiguously identify the relevant peptide from TSR1, metabolic labeling of cells expressing TSR1 and the cysteine-rich module led to incorporation of [(3)H]fucose into this construct. Mutation of the putative modified Ser/Thr residues in TSR2, TSR3, and TSR4 led to significantly decreased levels of secreted punctin-1. Similarly, expression of punctin-1 in Lec-13 cells that are deficient in conversion of GDP-mannose to GDP-fucose substantially decreased the levels of secreted protein, which were restored upon culture in the presence of exogenous l-fucose. In addition, mutation of the single N-linked oligosaccharide in punctin-1 led to decreased levels of secreted punctin-1. Taken together, the data define a critical role for N-glycosylation and O-fucosylation in the biosynthesis of punctin-1. From a broad perspective, these data suggest that O-fucosylation may be a widespread post-translational modification in members of the ADAMTS superfamily with possible regulatory consequences.

A complete expression profile of matrix-degrading metalloproteinases in Dupuytren's disease

PURPOSE

Dupuytren's disease (DD) is a common fibrotic condition of the palmar fascia, leading to deposition of collagen-rich cords and finger contractions. The metzincin superfamily contains key enzymes in the turnover of collagen and other extracellular matrix macromolecules. A number of broad-spectrum matrix metalloproteinase inhibitors, used in cancer clinical trials, caused side effects of DD-like contractures. We tested the hypothesis that changes in the expression of specific metalloproteinases underlie or contribute to the fibrosis and contracture seen in DD.

METHODS

We collected tissue from patients with DD and used normal palmar fascia as a control. We profiled the expression of the entire matrix metalloproteinase (MMP), tissue inhibitor of metalloproteinases (TIMP), and a disintegrin and metalloproteinase domain with thrombospondin motif (ADAMTS) gene families in these tissues using real-time reverse-transcription polymerase chain reaction.

RESULTS

A number of metalloproteinases and inhibitors are regulated in DD. The expression of 3 key collagenases, MMP1, MMP13, and MMP14 is increased significantly in the DD nodule, as is the expression of the collagen biosynthetic enzyme ADAMTS14. The expression of MMP7, an enzyme with broad substrate specificity, is increased in the DD nodule and remains equally expressed in the DD cord. TIMP1 expression is increased significantly in DD nodule compared with normal palmar fascia.

CONCLUSIONS

This study measured the expression of all MMP, ADAMTS, and TIMP genes in DD. Contraction and fibrosis may result from: (1) increased collagen biosynthesis mediated by increased ADAMTS-14; (2) an increased level of TIMP-1 blocking MMP-1- and MMP-13-mediated collagenolysis; and (3) contraction enabled by MMP-14-mediated pericellular collagenolysis (and potentially MMP-7), which may escape inhibition by TIMP-1. The complete expression profile will provide a knowledge-based approach to novel therapeutics targeting these genes.

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

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.

Tissue-specific differential antitumour effect of molecular forms of fractalkine in a mouse model of metastatic colon cancer

BACKGROUND AND AIMS

Fractalkine, a chemokine that presents as both a secreted and a membrane-anchored form, has been described as having tumour-suppressive activities in standard subcutaneous models. Here, we investigate the antitumour effect of fractalkine, in its three molecular forms, in two orthotopic models of metastatic colon cancer (liver and lung) and in the standard subcutaneous model.

METHODS

We have developed models of skin tumours, liver and pulmonary metastasis and compared the extent of tumour development between C26 colon cancer cells expressing either the native, the soluble, the membrane-bound fractalkine or none.

RESULTS

The native fractalkine exhibits the strongest antitumour effect, reducing the tumour size by 93% in the skin and by 99% in the orthotopic models (p<0.0001). Its overall effect results from a critical balance between the activity of the secreted and the membrane-bound forms, balance that is itself dependent on the target tissue. In the skin, both molecular variants reduce tumour development by 66% (p<0.01). In contrast, the liver and lung metastases are only significantly reduced by the soluble form (by 96%, p<0.002) whereas the membrane-bound variant exerts a barely significant effect in the liver (p = 0.049) and promotes tumour growth in the lungs. Moreover, we show a significant difference in the contribution of the infiltrating leukocytes to the tumour-suppressive activity of fractalkine between the standard and the orthotopic models.

CONCLUSIONS

Fractalkine expression by C26 tumour cells drastically reduces their metastatic potential in the two physiological target organs. Both molecular forms contribute to its antitumour potential but exhibit differential effects on tumour development depending on the target tissue.

Identification of an ADAMTS-4 cleavage motif using phage display leads to the development of fluorogenic peptide substrates and reveals matrilin-3 as a novel substrate

ADAMTS-4 and ADAMTS-5 are aggrecanases responsible for the breakdown of cartilage aggrecan in osteoarthritis. Multiple ADAMTS-4 cleavage sites have been described in several matrix proteins including aggrecan, versican, and brevican, but no concise predictive cleavage motif has been identified for this protease. By screening a 13-mer peptide library with a diversity of 10(8), we have identified the ADAMTS-4 cleavage motif E-(AFVLMY)-X(0,1)-(RK)-X(2,3)-(ST)-(VYIFWMLA), with Glu representing P1. Several 13-mer peptides containing this motif, including DVQEFRGVTAVIR and HNEFRQRETYMVF, were shown to be substrates for ADAMTS-4. These peptides were found to be specific substrates for ADAMTS-4 as they were not cleaved by ADAMTS-5. Modification of these peptides with donor (6-FAM) and acceptor (QSY-9) molecules resulted in the development of fluorescence-based substrates with a Km of approximately 35 microM. Furthermore, the role of Glu at P1 and Phe at P1' in binding and catalysis was studied by exploring substitution of these amino acids with the D-isomeric forms. Substitution of P1 with dGlu was tolerable for binding, but not catalysis, whereas substitution of P1' with dPhe precluded both binding and catalysis. Similarly, replacement of Glu with Asp at P1 abolished recognition and cleavage of the peptide. Finally, BLAST results of the ADAMTS-4 cleavage motif identified matrilin-3 as a new substrate for ADAMTS-4. When tested, recombinant ADAMTS-4 effectively cleaved intact matrilin-3 at the predicted motif at Glu435/Ala436 generating two species of 45 and 5 kDa.

Expression profiling of metalloproteinases and their inhibitors in synovium and cartilage

Cartilage destruction in osteoarthritis (OA) is thought to be mediated by two main enzyme families; the matrix metalloproteinases (MMPs) are responsible for cartilage collagen breakdown, whereas enzymes from the 'a disintegrin and metalloproteinase domain with thrombospondin motifs' (ADAMTS) family mediate cartilage aggrecan loss. Tissue inhibitors of metalloproteinases (TIMPs) regulate the activity of these enzymes. Although cartilage destruction in OA might be driven by the chondrocyte, low-grade synovitis is reported in patients with all grades of this disease.

Our earlier work profiling these gene families in cartilage identified a number of genes that are regulated in OA, which are hence implicated in the disease process. Because the synovium might contribute to cartilage-matrix destruction in OA, we have extended the screening in the current study. We have profiled MMP, ADAMTS and TIMP genes in both cartilage and synovium from patients with either OA of the hip or a fracture to the neck of femur (NOF), giving a more complete picture of proteolysis in this disease.

The four most significantly upregulated genes (P < 0.0001) in OA synovium compared to the fractured NOF are MMP28, ADAMTS16, ADAMTS17 and TIMP2. For MMP9, MMP10, MMP12, MMP17, MMP23, MMP28, ADAMTS4, and ADAMTS9, there is a significant correlation between expression levels in the synovium and cartilage, suggesting similar mechanisms of regulation. Additionally, we have shown that in cartilage the median level of steady-state mRNA for MMP13 is approximately 20-fold higher than MMP28 and approximately 1,500-fold higher than ADAMTS16, with expression of this latter gene approximately 150-fold higher in synovium than cartilage.

This study is the most comprehensive analysis of the metzincin family of proteinases in the joint to date and has identified several proteinase genes not previously reported to be expressed or regulated in synovium.

Metalloproteinase and inhibitor expression profiling of resorbing cartilage reveals pro-collagenase activation as a critical step for collagenolysis

Excess proteolysis of the extracellular matrix (ECM) of articular cartilage is a key characteristic of arthritis. The main enzymes involved belong to the metalloproteinase family, specifically the matrix metalloproteinases (MMPs) and a group of proteinases with a disintegrin and metalloproteinase domain with thrombospondin motifs (ADAMTS). Chondrocytes are the only cell type embedded in the cartilage ECM, and cell-matrix interactions can influence gene expression and cell behaviour. Thus, although the use of monolayer cultures can be informative, it is essential to study chondrocytes encapsulated within their native environment, cartilage, to fully assess cellular responses. The aim of this study was to profile the temporal gene expression of metalloproteinases and their endogenous inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), reversion-inducing cysteine-rich protein with Kazal motifs (RECK), and α₂-macroglobulin (α₂M), in actively resorbing cartilage. The addition of the pro-inflammatory cytokine combination of interleukin-1 (IL-1) + oncostatin M (OSM) to bovine nasal cartilage induces the synthesis and subsequent activation of pro-metalloproteinases, leading to cartilage resorption. We show that IL-1+OSM upregulated the expression of MMP-1, -2, -3, -9, 12, -13, -14, TIMP-1, and ADAMTS-4, -5, and -9. Differences in basal expression and the magnitude of induction were observed, whilst there was no significant modulation of TIMP-2, -3, RECK, or ADAMTS-15 gene expression. IL-1+OSM downregulated MMP-16,TIMP-4, and α₂M expression. All IL-1+OSM-induced metalloproteinases showed marked upregulation early in the culture period, whilst inhibitor expression was reduced throughout the stimulation period such that metalloproteinase production would be in excess of inhibitors. Moreover, although pro-collagenases were upregulated and synthesized early (by day 5), collagenolysis became apparent later with the presence of active collagenases (day 10) when inhibitor levels were low. These findings indicate that the activation cascades for pro-collagenases are delayed relative to collagenase expression, further confirm the coordinated regulation of metalloproteinases in actively resorbing cartilage, and support the use of bovine nasal cartilage as a model system to study the mechanisms that promote cartilage degradation.

Expression of ADAMs and their inhibitors in sputum from patients with asthma

ADAMs (a disintegrin and metalloprotease) constitute a family of cell surface proteins containing disintegrin and metalloprotease domains which associate features of adhesion molecules and proteases. ADAMTSs (a disintegrin and metalloprotease with thrombospondin motifs) bear thrombospondin type I motifs in C-terminal extremity, and most of them are secreted proteins. Because genetic studies have shown that ADAM-33 gene polymorphisms are associated with asthma, we designed this study to assess mRNA expression profile of several ADAM and ADAMTS proteases in sputum from patients with asthma and to investigate the relationship between expression of these proteases and asthma-associated inflammation and airway obstruction. mRNA expression profile of selected ADAM and ADAMTS proteinases (ADAM-8, -9, -10, -12, -15, -17, and -33; ADAMTS-1, -2, -15, -16, -17, -18, and -19), their physiological inhibitors TIMP-1 and TIMP-3, and RECK, a membrane-anchored MMP activity regulator, was obtained by RT-PCR analysis performed on cells collected by sputum induction from 21 patients with mild to moderate asthma and 17 healthy individuals. mRNA levels of ADAM-8, ADAM-9, ADAM-12, TIMP-1, and TIMP-3 were significantly increased, whereas mRNA levels coding for ADAMTS-1, ADAMTS-15, and RECK were significantly decreased in patients with asthma compared with control patients. ADAM-8 expression was negatively correlated with the forced expiratory volume at the first second (FEV(1)) (r = -0.57, P < 0.01), whereas ADAMTS-1 and RECK expressions were positively correlated to FEV(1) (r = 0.45, P < 0.05, and r = 0.55, P = 0.01, respectively). We conclude that expression of ADAMs and ADAMTSs and their inhibitors is modulated in airways from patients with asthma and that these molecules may play a role in the pathogenesis of asthma.

Expression of ADAMs and their inhibitors in sputum from patients with asthma

ADAMs (a disintegrin and metalloprotease) constitute a family of cell surface proteins containing disintegrin and metalloprotease domains which associate features of adhesion molecules and proteases. ADAMTSs (a disintegrin and metalloprotease with thrombospondin motifs) bear thrombospondin type I motifs in C-terminal extremity, and most of them are secreted proteins. Because genetic studies have shown that ADAM-33 gene polymorphisms are associated with asthma, we designed this study to assess mRNA expression profile of several ADAM and ADAMTS proteases in sputum from patients with asthma and to investigate the relationship between expression of these proteases and asthma-associated inflammation and airway obstruction. mRNA expression profile of selected ADAM and ADAMTS proteinases (ADAM-8, -9, -10, -12, -15, -17, and -33; ADAMTS-1, -2, -15, -16, -17, -18, and -19), their physiological inhibitors TIMP-1 and TIMP-3, and RECK, a membrane-anchored MMP activity regulator, was obtained by RT-PCR analysis performed on cells collected by sputum induction from 21 patients with mild to moderate asthma and 17 healthy individuals. mRNA levels of ADAM-8, ADAM-9, ADAM-12, TIMP-1, and TIMP-3 were significantly increased, whereas mRNA levels coding for ADAMTS-1, ADAMTS-15, and RECK were significantly decreased in patients with asthma compared with control patients. ADAM-8 expression was negatively correlated with the forced expiratory volume at the first second (FEV(1)) (r = -0.57, P < 0.01), whereas ADAMTS-1 and RECK expressions were positively correlated to FEV(1) (r = 0.45, P < 0.05, and r = 0.55, P = 0.01, respectively). We conclude that expression of ADAMs and ADAMTSs and their inhibitors is modulated in airways from patients with asthma and that these molecules may play a role in the pathogenesis of asthma.

Inhibition of aggrecan turnover in short-term explant cultures of bovine tendon

The large aggregating proteoglycan, aggrecan, better known for its physiological role in articular cartilage where it serves to facilitate resistance of compressive forces during joint articulation, is also present within the distinct functional regions of tendon (i.e., compressed/fibrocartilaginous and tensional). Previous studies demonstrate that an increased turnover of aggrecan occurs in tendon, which is mediated principally by the 'aggrecanases' and, as such, these proteinases may play an important role in the normal functioning of the tissue. In the present study, utilising bovine tendon explant culture systems, we demonstrated that aggrecanase-mediated tendon aggrecan turnover may be modulated by generic metalloproteinase inhibitors (i.e., the aggrecanase inhibitor, actinonin and the broad-spectrum MMP inhibitor, marimistat). As expected, no MMP-generated aggrecan catabolites were detected in the culture system, suggesting that tendon aggrecanases may be inhibited by marimistat. Furthermore, immunohistochemical analyses revealed that aggrecan metabolites are present in the endotenon, surrounding the collagen fibre bundles, suggesting that aggrecan may provide functions of water imbibement and resistance of reversible and repeated compressive loads manifest between the collagen fibres; these functions, in turn, may be associated with increased aggrecan turnover in this tissue. Thus, inhibition of tendon aggrecanases and consequently aggrecan turnover in this tissue, may be related to some of the deleterious effects observed in the tendons of patients undergoing drug therapy with broad-spectrum MMP inhibitors for cancer and arthritis.

Gene expression profiles of primary colorectal carcinomas, liver metastases, and carcinomatoses

Background

Despite the fact that metastases are the leading cause of colorectal cancer deaths, little is known about the underlying molecular changes in these advanced disease stages. Few have studied the overall gene expression levels in metastases from colorectal carcinomas, and so far, none has investigated the peritoneal carcinomatoses by use of DNA microarrays. Therefore, the aim of the present study is to investigate and compare the gene expression patterns of primary carcinomas (n = 18), liver metastases (n = 4), and carcinomatoses (n = 4), relative to normal samples from the large bowel.

Results

Transcriptome profiles of colorectal cancer metastases independent of tumor site, as well as separate profiles associated with primary carcinomas, liver metastases, or peritoneal carcinomatoses, were assessed by use of Bayesian statistics. Gains of chromosome arm 5p are common in peritoneal carcinomatoses and several candidate genes (including PTGER4, SKP2, and ZNF622) mapping to this region were overexpressed in the tumors. Expression signatures stratified on TP53 mutation status were identified across all tumors regardless of stage. Furthermore, the gene expression levels for the in vivo tumors were compared with an in vitro model consisting of cell lines representing all three tumor stages established from one patient.

Conclusion

By statistical analysis of gene expression data from primary colorectal carcinomas, liver metastases, and carcinomatoses, we are able to identify genetic patterns associated with the different stages of tumorigenesis.

Metalloproteinases: mediators of pathology and regeneration in the CNS

The matrix metalloproteinases and related A disintegrin and metalloproteinase enzymes are implicated in various diseases of the nervous system. However, metalloproteinases are increasingly being recognized as having beneficial roles during nervous system development and following injury. This review discusses general principles that govern the expression of metalloproteinases in the nervous system and their detrimental outcomes. It then focuses on the roles of metalloproteinases and their mechanisms in regulating neurogenesis, myelin formation and axonal growth. It is clear that metalloproteinases are important determinants in enabling recovery from injury to the nervous system.

ADAMTS1 is regulated by interleukin-1β, not by hypoxia, in chondrosarcoma

Angiogenesis is characteristic of cartilage tumors, not of normal cartilage tissue. In addition to our previous report on differential expression of proangiogenic vascular endothelial growth factor A (VEGF-A) in cartilage tumors, we analyzed the expression of a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1), which has been identified as a potent inhibitor of VEGF-A. We further used a chondrosarcoma cell line to study the effect of interleukin (IL)-1beta and hypoxia on the regulation of ADAMTS1 and VEGF-A expression. ADAMTS1 was detected by reverse transcriptase-polymerase chain reaction and immunohistochemistry in all analyzed samples from enchondromas, conventional chondrosacromas, and dedifferentiated chondrosarcomas without exception. In contrast to previous reports on other cancers, we did not detect a consistent decrease in ADAMTS1 expression in chondrosarcomas. Interleukin-1beta stimulation, not hypoxia, transcriptionally downregulated ADAMTS1 in chondrosarcoma cells, whereas VEGF-A expression was upregulated either by hypoxia or IL-1beta. We conclude that ADAMTS1 and VEGF-A in chondrosarcoma cells are regulated independently from each other. We believe that IL-1beta has a stronger impact on vascularization in chondrosarcomas than hypoxia, as both factors, ADAMTS1 and VEGF-A, are regulated in a way that favors angiogenesis.

Substrate Conformation Modulates Aggrecanase (ADAMTS-4) Affinity and Sequence Specificity

Protease-substrate interactions are governed by a variety of structural features. Although the substrate sequence specificities of numerous proteases have been established, "topological specificities," whereby proteases may be classified based on recognition of distinct three-dimensional structural motifs, have not. The aggrecanase members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family cleave a variety of proteins but do not seem to possess distinct sequence specificities. In the present study, the topological substrate specificity of ADAMTS-4 (aggrecanase-1) was examined using triple-helical or single-stranded poly(Pro) II helical peptides. Substrate topology modulated the affinity and sequence specificity of ADAMTS-4 with K(m) values indicating a preference for triple-helical structure. In turn, non-catalytic ADAMTS-4 domains were critical for hydrolysis of triple-helical and poly(Pro) II helical substrates. Comparison of ADAMTS-4 with MMP-1 (collagenase 1), MMP-13 (collagenase 3), trypsin, and thermolysin using triple-helical peptide (THP) and single-stranded peptide (SSP) substrates demonstrated that all five proteases possessed efficient "triple-helical peptidase" activity and fell into one of two categories: (k(cat)/K(m))(SSP) > (k(cat)/K(m))(THP) (thermolysin, trypsin, and MMP-13) or (k(cat)/K(m))(THP) > or = (k(cat)/K(m))(SSP) and (K(m))(SSP) > (K(m))(THP) (MMP-1 and ADAMTS-4). Overall these results suggest that topological specificity may be a guiding principle for protease behavior and can be utilized to design specific substrates and inhibitors. The triple-helical and single-stranded poly(Pro) II helical peptides represent the first synthetic substrates successfully designed for aggrecanases.

Mapping von Willebrand factor A domain binding sites on a snake venom metalloproteinase cysteine-rich domain

The PIII class of the snake venom metalloproteinases (SVMPS) are acknowledged to be one of the major hemorrhage producing toxins in crotalid venoms. This class of SVMPS are structurally distinguished by the presence of disintegrin-like and cysteine-rich domains carboxy to the metalloproteinase domain and thus share structural homology with many of the ADAMs proteins. It has been suggested that the presence of the carboxy domain are the key structural determinants for potent hemorrhagic activity in that they may serve to target the proteinases to specific key extracellular matrix and cell surface substrates for proteolysis leading to hemorrhage production at the capillaries. Following from previous studies in our laboratory in this investigation we scanned the cysteine-rich domain of the PIII hemorrhagic SVMP jararhagin using synthetic peptides in an attempt to identify regions which could bind to von Willebrand factor (vWF), a known binding partner for jararhagin. From these studies we identified two such peptide, Jar6 and Jar7 that could support binding to vWF as well as block the recombinant cysteine-rich domain of jararhagin binding to vWF. Using the coordinates for the recently solved crystal structure of the PIII SVMP VAP1, we modeled the structure of jararhagin and attempted to dock the modeled cysteine-rich structure of that protein to the A1 domain of vWF. These studies indicated that effective protein-protein interaction between the two ligands was possible and supported the data indicating that the Jar6 peptide was involved, whereas the Jar7 peptide was observed to be sterically blocked from interaction. In summary, our studies have identified a region on the cysteine-rich domain of a PIII SVMP that interacts with vWF and based on molecular modeling could be involving in the interaction of the cysteine-rich domain of the SVMP with the A1 domain of vWF thus serving to target the toxin to the protein for subsequent proteolytic degradation.

Regulation of A Disintegrin And Metalloproteinase with ThromboSpondin repeats-1 expression in human endometrial stromal cells by gonadal steroids involves progestins, androgens, and estrogens

CONTEXT

Gonadal steroids are key regulators of the extracellular matrix remodeling events that occur in the human endometrium during each menstrual cycle. The spatiotemporal expression of A Disintegrin And Metalloproteinase with ThromboSpondin repeats (ADAMTS)-1 in human endometrial stroma in vivo suggests that this novel metalloproteinase may contribute to this tightly regulated developmental process.

OBJECTIVE

The objective of the study was to determine whether progesterone (P4), 17beta-estradiol (E2), or the nonaromatizable androgen dihydrotestosterone (DHT), alone or in combination, is capable of regulating ADAMTS-1 mRNA and protein levels in human endometrial stromal cells in a concentration- and time-dependent manner.

DESIGN

A real-time quantitative PCR strategy and Western blotting were used to examine ADAMTS-1 mRNA and protein expression levels in primary cultures of human endometrial stromal cells.

RESULTS

P4 and DHT but not E2 increased the levels of the ADAMTS-1 mRNA transcript and protein species (110 kDa) present in endometrial stromal cells in vitro in a concentration- and time-dependent manner. A combination of P4 and DHT resulted in an additional increase in stromal ADAMTS-1 expression, whereas E2 attenuated the regulatory effects of P4 and DHT in a concentration-dependent manner. The antisteroidal compounds, mifepristone (RU486) and hydroxyflutamide, were also found to inhibit specifically the P4- and DHT-mediated increase in ADAMTS-1 mRNA and protein expression levels in these primary cell cultures in a concentration-dependent manner, respectively.

CONCLUSIONS

These studies demonstrate that progestins, androgens, and estrogens, alone and in combination, have distinct regulatory effects on ADAMTS-1 mRNA and protein expression levels in human endometrial stromal cells in vitro.

Matrix metalloproteinase 10 promotion of collagenolysis via procollagenase activation: implications for cartilage degradation in arthritis

OBJECTIVE

We have previously reported the up-regulation of matrix metalloproteinase 10 (MMP-10) following treatment with the procatabolic stimulus of interleukin-1 (IL-1) and oncostatin M (OSM) in chondrocytes. Although MMP-10 is closely related to MMP-3, little is known about the role of MMP-10 in cartilage catabolism. The purpose of this study was to determine whether MMP-10 is expressed in connective tissue cells and to assess how it may contribute to cartilage collagenolysis.

METHODS

MMP gene expression was assessed by real-time polymerase chain reaction using RNA from human articular chondrocytes and synovial fibroblasts stimulated with IL-1 plus OSM or tumor necrosis factor alpha (TNFalpha) plus OSM. Synovial fluid levels of MMP-10 were determined by specific immunoassay. Recombinant procollagenases were used in activation studies. Immunohistochemistry assessed MMP-10 expression in diseased joint tissues.

RESULTS

MMP-10 expression was confirmed in both chondrocytes and synovial fibroblasts following stimulation with either IL-1 plus OSM or TNFalpha plus OSM, and MMP-10 was detected in synovial fluid samples from patients with various arthropathies. Exogenous MMP-10 significantly enhanced collagenolysis from IL-1 plus OSM-stimulated cartilage, and MMP-10 activated proMMP-1, proMMP-8, and proMMP-13. Immunohistochemistry revealed the presence of MMP-10 in the synovium and cartilage of an IL-1 plus OSM-induced model of arthritis as well as in samples of diseased human tissues.

CONCLUSION

We confirm that both synovial fibroblasts and articular chondrocytes express MMP-10 following treatment with procatabolic stimuli. Furthermore, the detectable levels of synovial fluid MMP-10 and the histologic detection of this proteinase in diseased joint tissues strongly implicate MMP-10 in the cartilage degradome during arthritis. The ability of MMP-10 to superactivate procollagenases that are relevant to cartilage degradation suggests that this activation represents an important mechanism by which this MMP contributes to tissue destruction in arthritis.

Virus-derived genes for insect-resistant transgenic plants

Insect viruses have evolved to counter physiological barriers to infection presented by the host insect. For the Lepidoptera (butterflies and moths), these barriers include (1) the peritrophic membrane (PM) lining the gut, which presents a physical barrier to virus infection of the midgut epithelial cells, (2) the basement membrane (BM) that overlies the gut thereby restricting secondary infection of other tissues, and (3) the immune system of the host insect. Hence, insect viruses provide a resource for genes that disrupt host physiology in a specific manner, and these genes in turn serve as a resource both for the study of physiological processes, and for disruption of these processes for pest management purposes. There are several examples of the application of genes used by an insect virus to overcome the PM barrier for production of insect-resistant transgenic plants. There are other examples of intrahemocoelic effectors, such as BM-degrading proteases that can only be used with an appropriate system for delivery of the agent from the gut into the hemocoel (body cavity) of the insect pest. In this chapter, we describe (1) baculovirus- and entomopoxvirus-derived genes that alter the physiology of the host insect, (2) use of these and homologous genes for production of insect-resistant transgenic plants, (3) other viral genes that have potential for use in development of insect-resistant transgenic plants, and (4) the use of plant lectins for delivery of intrahemocoelic toxins from transgenic plants. Plant expression of polydnavirus-derived genes is described by Gill et al. (this volume, pp. 393-426).