Purification of an insect derived recombinant human ADAMTS-1 reveals novel gelatin (type I collagen) degrading activities

Investigation roles of Adamts1 and Adamts5 in scleral fibroblasts under hypoxia and mice with form-deprived myopia

Scleral hypoxia is considered a trigger in scleral remodeling-induced myopia. Identifying differentially expressed molecules within the sclera is essential for understanding the mechanism of myopia. We developed a scleral fibroblast hypoxia model and conducted RNA sequencing and bioinformatic analysis. RNA interference technology was then applied to knock down targeted genes with upregulated expression, followed by an analysis of COLLAGEN I protein level. Microarray data analysis showed that the expression of Adamts1 and Adamts5 were upregulated in fibroblasts under hypoxia (t-test, p < 0.05). Western blot analysis confirmed increased protein levels of ADAMTS1 and ADAMTS5, and a concurrent decrease in COLLAGEN I in hypoxic fibroblasts. The knockdown of either Adamts1 or Adamts5 in scleral fibroblasts under hypoxia resulted in an upregulation of COLLAGEN I. Moreover, a form-deprivation myopia (FDM) mouse model was established for validation. The sclera tissue from FDM mice exhibited increased levels of ADAMTS1 and ADAMTS5 protein and a decrease in COLLAGEN I, compared to controls. The study suggests that Adamts1 and Adamts5 may be involved in scleral remodeling induced by hypoxia and the development of myopia.

ADAMTS1 induces epithelial-mesenchymal transition pathway in non-small cell lung cancer by regulating TGF-β

Non-small cell lung cancer (NSCLC) accounts for approximately 80% of all lung cancers. Identifying key molecular targets related to the initiation, development, and metastasis of lung cancer is important for its diagnosis and target therapy. The ADAMTS families of multidomain extracellular protease enzymes have been reported to be involved in many physiological processes. In this study, we found that ADAMTS1 was highly expressed in NSCLC tissues, which promoted cell proliferation, migration, invasion, and epithelial to mesenchymal transition (EMT) of NSCLC cells. In the NSCLC tumor metastasis model involving nude mice, overexpression of ADAMTS1 promoted EMT and lung metastasis of tumor cells. Moreover, ADAMTS1 positively regulated TGF-β expression, and TGF-β was highly expressed in NSCLC tumor tissues. si-TGF-β or inhibition of TGF-β expression through the short peptide KTFR on ADAMTS1 protein could reverse the oncogenic effects of ADAMTS1 on lung cancer cells. Taken together, ADAMTS1 functioned as an oncogene in NSCLC cells by promoting TGF-β expression, indicating that ADAMTS1 has important regulatory roles in the progression of NSCLC.

An Optimized Purification Design for Extracting Active ADAMTS13 from Conditioned Media

ADAMTS13 is a hemostatic enzyme that breaks down pro-thrombotic ultra-large multimers of von Willebrand factor (VWF). The deficiency of ADAMTS13 increases VWF-mediated thrombogenic potential and may lead to thrombotic thrombocytopenic purpura (TTP). Recently, clinical studies have shown the development of acquired TTP after COVID-19 infection and a correlation between low ADAMTS13 plasma levels and increased mortality. As a result, investigating ADAMTS13 as a potential recombinant therapeutic is of broad interest in the field of hematology. ADAMTS13 is considered challenging to purify in its biologically active state. Current purification methods utilize immobilized metal ions, which can interfere with ADAMTS13 metalloprotease activity. For this reason, we optimized an alternative strategy to isolate milligram quantities of highly active recombinant ADAMTS13 (rADAMTS13) from conditioned media after exogenous expression in human cell line, HEK293. HEK293 cells stably expressing C-terminal V5-His-tagged ADAMTS13 were grown in two parallel systems, culture bottles and flasks, for identifying an optimal cultivation strategy. Subsequently, we employed anion exchange followed by anti-V5-tag affinity chromatography to purify rADAMTS13, and extracted rADAMTS13 of high specific activity while preserving its native post-translational modifications. In addition, this process has been optimized and scaled up to produce active rADAMTS13 at levels sufficient for laboratory-scale structural, enzymatic, and biochemical studies.

An anti-ADAMTS1 treatment relieved muscle dysfunction and fibrosis in dystrophic mice

Duchenne Muscular Dystrophy (DMD) is caused by mutations in the dystrophin gene, accompanied by aberrant extracellular matrix synthesis and muscle damage. ADAMTS1 metalloproteinase was reported increased in dystrophin-deficient mdx mouse. The aim of this study was to explore the role of ADAMTS1 in muscle function, fibrosis and damage, and respiratory function of mdx mice. 102 DMD patients and their mothers were included in this study. Multiplex ligation dependent probe amplification (MLPA) assay and Next-generation sequencing (NGS) were adopted to do genetic diagnosis. Dystrophin-deficient mdx mice were treated with anti-ADAMTS1 antibody (anti-ADAMTS1) for three weeks. The results showed that ADAMTS1 was increased in gastrocnemius muscle of mdx mice and serum of DMD patients. Anti-ADAMTS1 treatment increased Versican transcription but suppressed versican protein expression. Besides, we found anti-ADAMTS1 improved muscle strength, diaphragm and extensor digitorum longus muscles functions in mdx mice. Meanwhile, muscle fibrosis and damage were attenuated in anti-ADAMTS1 treated dystrophic mice. In summary, anti-ADAMTS1 antibody relieved muscle dysfunction and fibrosis in dystrophic mice. It is suggested that ADAMTS1 is a potential target for developing new biological therapies for DMD.

Transcriptome analysis to unravel the gene expression profile of ovarian follicular development in Magang goose

Magang geese exhibit a unique characteristic of follicular development, with eight largest orderly arranged pre-ovulatory follicles in the abdominal cavity. However, little is known about the mechanisms underlying this follicular development. This study aimed to compare gene expression profiles of granulosa cells (GCs) at different stages of follicular development and provide comprehensive insights into follicle selection and the mechanisms underlying the well-defined follicle hierarchy in Magang geese. GCs of large white follicles (LWFs), small yellow follicles (SYFs), F8, F4, and F1 were used for RNA-seq analysis; 374, 1117, 791, and 593 genes were differentially expressed in stages LWFs to SYFs, SYFs to F8, F8 to F4, and F4 to F1, respectively, suggesting that these genes contribute to follicle selection and development. Reliability of sequencing data was verified through qPCR analysis of 24 genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways revealed a complex mechanism that remodels the extracellular matrix and turnover of extracellular matrix components in follicular development and ovulation and involves multiple pathway, such as focal adhesion, adherens junction, and extracellular matrix–receptor interaction. Some unique characteristics were observed during the different follicular development stages. For instance, some differentially expressed genes were enriched in progesterone-mediated oocyte maturation and steroid biosynthesis from stage SYFs to F8, whereas others were enriched in actin cytoskeleton regulation and vascular smooth muscle contraction from stage F4 to F1. These findings enhance our current understanding of GC function and ovarian follicles during the key stages of follicular development.

Cardiac fibrosis in regenerative medicine: destroy to rebuild

The major limitations for cardiac regeneration in patients after myocardial infarction (MI) are the wide loss of cardiomyocytes and the adverse structural alterations of extracellular matrix (ECM). Cardiac fibroblast differentiation into myofibroblasts (MFB) leads to a huge deposition of ECM and to the subsequent loss of ventricular structural integrity. All these molecular events depict the fundamental features at the basis of the post-MI fibrosis and deserve in depth cellular and molecular studies to fill the gap in the clinical practice. Indeed, to date, there are no effective therapeutic approaches to limit the post-MI massive fibrosis development. In this review we describe the involvement of integrins and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)/ADAMTS-like (ADAMTSL) proteins in cardiac reparative pro-fibrotic response after MI, proposing some of them as novel potential pharmacological tools.

Handling Metalloproteinases

Substrate cleavage by metalloproteinases involves nucleophilic attack on the scissile peptide bond by a water molecule that is polarized by a catalytic metal, usually a zinc ion, and a general base, usually the carboxyl group of a glutamic acid side chain. The zinc ion is most often complexed by imidazole nitrogens of histidine side chains. This arrangement suggests that the physiological pH optimum of most metalloproteinases is in the neutral range. In addition to their catalytic metal ion, many metalloproteinases contain additional transition metal or alkaline earth ions, which are structurally important or modulate the catalytic activity. As a consequence, these enzymes are generally sensitive to metal chelators. Moreover, the catalytic metal can be displaced by adventitious metal ions from buffers or biological fluids, which may fundamentally alter the catalytic function. Therefore, handling, purification, and assaying of metalloproteinases require specific precautions to warrant their stability.

Insights on ADAMTS proteases and ADAMTS-like proteins from mammalian genetics

The mammalian ADAMTS superfamily comprises 19 secreted metalloproteinases and 7 ADAMTS-like proteins, each the product of a distinct gene. Thus far, all appear to be relevant to extracellular matrix function or to cell-matrix interactions. Most ADAMTS functions first emerged from analysis of spontaneous human and animal mutations and genetically engineered animals. The clinical manifestations of Mendelian disorders resulting from mutations in ADAMTS2, ADAMTS10, ADAMTS13, ADAMTS17, ADAMTSL2 and ADAMTSL4 identified essential roles for each gene, but also suggested potential cooperative functions of ADAMTS proteins. These observations were extended by analysis of spontaneous animal mutations, such as in bovine ADAMTS2, canine ADAMTS10, ADAMTS17 and ADAMTSL2 and mouse ADAMTS20. These human and animal disorders are recessive and their manifestations appear to result from a loss-of-function mechanism. Genome-wide analyses have determined an association of some ADAMTS loci such as ADAMTS9 and ADAMTS7, with specific traits and acquired disorders. Analysis of genetically engineered rodent mutations, now achieved for over half the superfamily, has provided novel biological insights and animal models for the respective human genetic disorders and suggested potential candidate genes for related human phenotypes. Engineered mouse mutants have been interbred to generate combinatorial mutants, uncovering cooperative functions of ADAMTS proteins in morphogenesis. Specific genetic models have provided crucial insights on mechanisms of osteoarthritis (OA), a common adult-onset degenerative condition. Engineered mutants will facilitate interpretation of exome variants identified in isolated birth defects and rare genetic conditions, as well as in genome-wide screens for trait and disease associations. Mammalian forward and reverse genetics, together with genome-wide analysis, together constitute a powerful force for revealing the functions of ADAMTS proteins in physiological pathways and health disorders. Their continuing use, together with genome-editing technology and the ability to generate stem cells from mutants, presents numerous opportunities for advancing basic knowledge, human disease pathways and therapy.

The calcineurin/NFAT pathway is activated in diagnostic breast cancer cases and is essential to survival and metastasis of mammary cancer cells

Nuclear factor of activated T cells 1 (NFAT1) expression has been associated with increased migratory/invasive properties of mammary tumor-derived cell lines in vitro. It is unknown, however, if NFAT activation actually occurs in breast cancer cases and whether the calcineurin/NFAT pathway is important to mammary tumorigenesis. Using a cohort of 321 diagnostic cases of the major subgroup of breast cancer, we found Cn/NFAT pathway activated in ER⁻PR⁻HER2⁻ triple-negative breast cancer subtype, whereas its prevalence is less in other subgroups. Using a small hairpin RNA-based gene expression silencing approach in murine mammary tumor cell line (4T1), we show that not only NFAT1 but also NFAT2 and their upstream activator Cn are essential to the migratory and invasive properties of mammary tumor cells. We also demonstrate that Cn, NFAT1 and NFAT2 are essential to the tumorigenic and metastatic properties of these cells in mice, a phenotype which coincides with increased apoptosis in vivo. Finally, global gene expression analyses identified several NFAT-deregulated genes, many of them being previously associated with mammary tumorigenesis. In particular, we identified the gene encoding a disintegrin and metalloproteinase with thrombonspondin motifs 1, as being a potential direct target of NFAT1. Thus, our results show that the Cn/NFAT pathway is activated in diagnostic cases of breast cancers and is essential to the tumorigenic and metastatic potential of mammary tumor cell line. These results suggest that pharmacological inhibition of the Cn/NFAT pathway at different levels could be of therapeutical interest for breast cancer patients.

TGFβ loss activates ADAMTS-1-mediated EGF-dependent invasion in a model of esophageal cell invasion

The TGFβ signaling pathway is essential to epithelial homeostasis and is often inhibited during progression of esophageal squamous cell carcinoma. Recently, an important role for TGFβ signaling has been described in the crosstalk between epithelial and stromal cells regulating squamous tumor cell invasion in mouse models of head-and-neck squamous cell carcinoma (HNSCC). Loss of TGFβ signaling, in either compartment, leads to HNSCC however, the mechanisms involved are not well understood. Using organotypic reconstruct cultures (OTC) to model the interaction between epithelial and stromal cells that occur in dysplastic lesions, we show that loss of TGFβ signaling promotes an invasive phenotype in both fibroblast and epithelial compartments. Employing immortalized esophageal keratinocytes established to reproduce common mutations of esophageal squamous cell carcinoma, we show that treatment of OTC with inhibitors of TGFβ signaling (A83-01 or SB431542) enhances invasion of epithelial cells into a fibroblast-embedded Matrigel/collagen I matrix. Invasion induced by A83-01 is independent of proliferation but relies on protease activity and expression of ADAMTS-1 and can be altered by matrix density. This invasion was associated with increased expression of pro-inflammatory cytokines, IL1 and EGFR ligands HB-EGF and TGFα. Altering EGF signaling prevented or induced epithelial cell invasion in this model. Loss of expression of the TGFβ target gene ROBO1 suggested that chemorepulsion may regulate keratinocyte invasion. Taken together, our data show increased invasion through inhibition of TGFβ signaling altered epithelial-fibroblasts interactions, repressing markers of activated fibroblasts, and altering integrin-fibronectin interactions. These results suggest that inhibition of TGFβ signaling modulates an array of pathways that combined promote multiple aspects of tumor invasion.

The metalloproteinase ADAMTS1: a comprehensive review of its role in tumorigenic and metastatic pathways

As it was first characterized in 1997, the ADAMTS (A Disintegrin and Metalloprotease with ThromboSpondin motifs) metalloprotease family has been associated with many physiological and pathological conditions. Of the 19 proteases belonging to this family, considerable attention has been devoted to the role of its first member ADAMTS1 in cancer. Elevated ADAMTS1 promotes pro-tumorigenic changes such as increased tumor cell proliferation, inhibited apoptosis and altered vascularization. Importantly, it facilitates significant peritumoral remodeling of the extracellular matrix environment to promote tumor progression and metastasis. However, discrepancy exists, as several studies also depict ADAMTS1 as a tumor suppressor. This article reviews the current understanding of ADAMTS1 regulation and the consequence of its dysregulation in primary cancer and ADAMTS1-mediated pathways of cancer progression and metastasis.

Over-expression of Adamts1 in mice alters bone mineral density

ADAMTS1, a secreted multifunctional metalloproteinase with disintegrin and thrombospondin motifs, is an early response gene of parathyroid hormone (PTH) in osteoblasts. Mice engineered to lack Adamts1 are smaller compared to wild-type (WT) mice and ADAMTS1 metalloproteinase activity has been shown to increase osteoblastic growth in collagen gels. However, there are no reports investigating the consequence of Adamts1 over-expression on bone tissue in vivo. Here, we analyze bones of female and male transgenic (TG) mice over-expressing mouse Adamts1 using peripheral quantitative computed tomography to evaluate its effect on bone shape and mineral density. Western blotting of protein extracts and immunohistochemistry of bone sections reveal increased presence of Adamts1 protein in TG bones compared to WT bones. Phenotypic analyses of femur show that female TG mice have reduced metaphyseal total density, trabecular bone mineral density and trabecular mineral content. In contrast, male TG mice which were without changes in the metaphysis showed increased total density and cortical density at the mid-diaphysis cortical site. Female TG mice showed no significant changes at the cortical site compared to WT mice. Furthermore, diaphyseal endosteal compartment was only affected in male TG mice. Along these lines, Adamts1 increased blood levels of PTH only in females whereas it reduced osteocalcin levels only in males. These results reveal that Adamts1 has an impact on bone mineral density and thus further confirm Adamts1 as a potent regulator of bone remodeling.

Fluorescence resonance energy transfer assay for high-throughput screening of ADAMTS1 inhibitors

A disintegrin and metalloprotease with thrombospondin type I motifs-1 (ADAMTS1) plays a crucial role in inflammatory joint diseases and its inhibitors are potential candidates for anti-arthritis drugs. For the purposes of drug discovery, we reported the development and validation of fluorescence resonance energy transfer (FRET) assay for high-throughput screening (HTS) of the ADAMTS1 inhibitors. A FRET substrate was designed for a quantitative assay of ADAMTS1 activity and enzyme kinetics studies. The assay was developed into a 50-µL, 384-well assay format for high throughput screening of ADAMTS1 inhibitors with an overall Z' factor of 0.89. ADAMTS1 inhibitors were screened against a diverse library of 40,960 total compounds with the established HTS system. Four structurally related hits, naturally occurring compounds, kuwanon P, kuwanon X, albafuran C and mulberrofuran J, extracted from the Chinese herb Morus alba L., were identified for further investigation. The results suggest that this FRET assay is an excellent tool, not only for measurement of ADAMTS1 activity but also for discovery of novel ADAMTS1 inhibitors with HTS.

ADAMTS1 cleavage of versican mediates essential structural remodeling of the ovarian follicle and cumulus-oocyte matrix during ovulation in mice

Remodeling of ovarian follicle extracellular matrix is essential for ovulation and vascularization of the corpus luteum (CL). Formation of the cumulus matrix around oocytes also plays an important role in ovulation and subsequent fertilization of oocytes. ADAMTS1 is an extracellular metalloprotease induced in ovarian follicles by ovulatory hormones and is required for fertility. In this study, we identified ADAMTS1-mediated structural and morphological changes in remodeling of the follicle and cumulus oocyte complex (COC). In Adamts1(-/-) mice, the ovulation rate was 77% reduced and fertilization of ovulated oocytes was reduced a further 63%, resulting in a reduced number of litters and pups per litter. Morphological assessment of peri-ovulatory ovaries revealed abnormal morphogenesis with a lack of thecal/vascular invagination in the basal region of follicles. Cleavage of the ADAMTS1 substrate, versican, at these invaginating regions was abundant in Adamts1(+/-) but undetectable in Adamts1(-/-) ovaries, indicating that processing of versican by ADAMTS1 is involved in ovulating follicle remodeling. Versican and hyaluronan localization was abnormal during COC matrix expansion, and versican persisted beyond the expected time of fertilization in Adamts1(-/-) but was catabolized and cleared from control COC. The results demonstrate that ADAMTS1 is critical in both ovulation and fertilization processes in vivo. The protease activity of ADAMTS1 mediates neomorphogenesis of the ovulating follicle wall and COC matrix necessary for successful ovulation and fertilization, as well as subsequent catabolism of versican required for degradation of COC matrix after fertilization.

ADAMTS1, a putative anti-angiogenic factor, is decreased in human prostate cancer

OBJECTIVE

To investigate the expression of 'ADAM metallopeptidase with thrombospondin type I motif, 1' (ADAMTS1) in human prostate cancer, and to study its relationship to microvessel density (MVD) and metastasis. ADAMTS1 has been described as an anti-angiogenic and antitumour factor, but its function in prostate cancer is unknown.

PATIENTS AND METHODS

ADAMTS1 expression was evaluated by immunohistochemistry in specimens obtained by transurethral resection of the prostate from patients with hormone-naïve and hormone-refractory prostate tumours, including adjacent benign tissue. A semiquantitative scoring system was used for evaluating the staining. MVD was quantified by counting the number of CD34-positive blood vessels.

RESULTS

ADAMTS1 was strongly expressed in the luminal epithelial cells in benign prostate glands, whereas expression was significantly lower in prostate cancer cells. There was no obvious difference between hormone-naïve and hormone-refractory tumours, and ADAMTS1 expression did not correlate with Gleason score. However, in hormone-refractory tumours from patients with metastatic disease, the expression of ADAMTS1 was significantly lower than in tumours from patients without metastases. Furthermore, the MVD was higher in hormone-refractory than in hormone-naïve tumours and benign tissue, and MVD correlated with Gleason score. There was no association between ADAMTS1 and MVD in the hormone-naïve tumours, while hormone-refractory tumours with low ADAMTS1 expression had a higher MVD than those with moderate/high expression.

CONCLUSION

ADAMTS1 expression is decreased in prostate cancer, and might be involved in the early steps of prostate cancer development. Further, ADAMTS1 might have an anti-angiogenic and antimetastatic role in hormone-refractory prostate cancer, where low ADAMTS1 expression is associated with a high MVD and metastasis.

Macro- and micronutrient dyshomeostasis in the adverse structural remodelling of myocardium

Hypertension and heart failure are worldwide health problems of ever-increasing proportions. A failure of the heart, during either systolic and/or diastolic phases of the cardiac cycle, has its origins rooted in an adverse structural, biochemical, and molecular remodelling of myocardium that involves its cellular constituents, extracellular matrix, and intramural coronary vasculature. Herein we focus on the pathogenic role of a dyshomeostasis of several macro- (i.e. Ca(2+) and Mg(2+)) and micronutrients (i.e. Zn(2+), Se(2+), and vitamin D) in contributing to adverse remodelling of the myocardium and its failure as a pulsatile muscular pump. An improved understanding of how these macro- and micronutrients account for the causes and consequences of adverse myocardial remodelling carries with it the potential of identifying new biomarkers predictive of risk, onset and progression, and response to intervention(s), which could be monitored non-invasively and serially over time. Moreover, such incremental knowledge will serve as the underpinning to the development of novel strategies aimed at preventing and/or regressing the ongoing adverse remodelling of myocardium. The time is at hand to recognize the importance of macro- and micronutrient dyshomeostasis in the evaluation and management of hypertension and heart failure.

Altered expression of genes regulating angiogenesis in experimental androgen-independent prostate cancer

BACKGROUND

The aim of this study was to investigate how the expression of genes regulating angiogenesis is altered when prostate cancer cells progress into androgen-independency.

METHODS

A gene array specific for angiogenesis was used to compare the human prostate cancer cell line LNCaP (androgen-dependent) with its more angiogenic and tumorigenic subline LNCaP-19 (androgen-independent). Results were verified with real-time RT-PCR, and further investigations were focused on the angiogenesis inhibitor a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1). Expression of ADAMTS1 was investigated in vitro as well as in subcutaneous tumors with real-time RT-PCR and Western blotting. Microvessel density (MVD), versican proteolysis and protein levels of TIMP-2 and TIMP-3, known as ADAMTS1 inhibitors, were also analyzed in tumor xenografts.

RESULTS

The gene array revealed decreased expression of ADAMTS1, ephrin-A5, fibronectin 1, and neuropilin 1 in LNCaP-19 compared to LNCaP, while expression of midkine and VEGF were increased. Further studies showed that mRNA and protein levels of ADAMTS1 were significantly lower in LNCaP-19 compared to LNCaP, both in vitro and in subcutaneous tumors. The amount of ADAMTS1 correlated negatively with MVD, but no relation was found between ADAMTS1 and versican proteolysis.

CONCLUSIONS

Expression of several genes associated with angiogenesis was altered during transition into androgen-independency. Among these, a significant decrease was found for ADAMTS1, whose expression inversely correlated with MVD. Its role in progression of prostate cancer needs further investigation, but this inhibitor of angiogenesis could be an interesting candidate for future anti-angiogenic therapy.

ADAMTS-1 increases the three-dimensional growth of osteoblasts through type I collagen processing

The multi-domain neutral endopeptidase, ADAMTS-1 (a disintegrin and metalloprotease with thrombospondin repeats) is induced by parathyroid hormone (PTH) in rat osteoblasts and has therefore been suggested to be involved in initiation of bone remodeling. However, its function(s) in bone cells have not been studied. Here, we first establish that ADAMTS-1 protein is rapidly and transiently produced by human primary osteoblasts in response to PTH (1-34). We also show that ADAMTS-1 is specifically in close proximity to collagen fibrils in bone tissue using ultrastructural immunolabeling. To study the consequence(s) of ADAMTS-1 metalloprotease production in osteoblastic cells, human osteosarcoma cells (SaOS-2), were forced to express either wild-type (wtATS) or a point-mutated (pmATS) metalloprotease dead ADAMTS-1. SaOS-2 cells expressing wtATS had a growth advantage and increased collagenolytic activity when seeded inside a collagen type I gel but exhibited a reduced migration in a scratch wound assay. Immunolabeling of moving cells shows ADAMTS-1 to be located towards the direction of cellular migration. Finally, Western analysis demonstrated excess accumulation of mature collagen type I alpha1 species in the extracellular matrix together with increased release of distinct small collagen fragments into the conditioned media, by cultures of wtATS cells compared to pmATS cells. These results show that ADAMTS-1 has both the opportunity in bone and capability in vitro to induce collagen type I processing, together with a positive influence on osteoblastic three-dimensional growth. Although it is not clear at present if ADAMTS-1 promotes collagen degradation directly or indirectly, it shows that ADAMTS-1 activity can have a profound influence on the osteoblast phenotype, inhibiting migration on a planar substrate but enhancing growth in a collagen scaffold. These findings further establish ADAMTS-1 as a potentially important protein in PTH induced bone remodeling.

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.

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.

Requirement for ADAMTS-1 in extracellular matrix remodeling during ovarian folliculogenesis and lymphangiogenesis

Murine ovarian folliculogenesis commences after birth involving oocyte growth, somatic cell differentiation and structural remodeling of follicle stromal boundaries. The extracellular metalloproteinase ADAMTS-1 has activity against proteoglycans and collagen and is produced by the granulosa cells of ovarian follicles. Mice with ADAMTS-1 gene disruption are subfertile due to an unknown mechanism resulting in severely reduced ovulation. Here we show that ADAMTS-1 is necessary for structural remodeling during ovarian follicle growth. A significant reduction in the number of healthy growing follicles and corresponding follicle dysmorphogenesis commencing at the stage of antrum formation was identified in ADAMTS-1-/- ovaries. Morphological analysis and immunostaining of basement membrane components identified stages of follicle dysgenesis from focal disruption in ECM integrity to complete loss of follicular structures. Cells expressing the thecal marker Cyp-17 were lost from dysgenic regions, while oocytes and dispersed cells expressing the granulosa cell marker anti-mullerian hormone persisted in ovarian stroma. Furthermore, we found that the ovarian lymphatic system develops coincidentally with follicular development in early postnatal life but is severely delayed in ADAMTS-1-/- ovaries. These novel roles for ADAMTS-1 in structural maintenance of follicular basement membranes and lymphangiogenesis provide new mechanistic understanding of folliculogenesis, fertility and disease.