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Camilla Fröhlich,
Marie Klitgaard,
Julie B Noer,
Alexander Kotzsch,
Camilla Nehammer,
Pauliina Kronqvist,
Jens Berthelsen,
Carl Blobel,
Marie Kveiborg,
Reidar Albrechtsen, Ulla M Wewer
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ABSTRACT: ADAM12 is a metalloprotease implicated in cancer progression. ADAM12 can activate membrane-anchored proteins, such as sonic hedgehog, Delta-like 1, and certain epidermal growth factor receptor ligands, through a process called ectodomain shedding. We screened several membrane-anchored proteins to further dissect the substrate profile of ADAM12-mediated ectodomain shedding, and found shedding of five previously unreported substrates (Kitl1, VE-cadherin, Flk-1, Tie-2, and VCAM-1), of which the latter four are specifically expressed by endothelial cells. We also observed that ADAM12 expression was increased in the tumour vasculature of infiltrating ductal carcinoma of the human breast as compared with little to no expression in normal breast-tissue vasculature, suggesting a role for ADAM12 in tumour vessels. These data prompted us to further evaluate ADAM12-mediated shedding of two endothelial cell proteins, VE-cadherin and Tie-2. Endogenous ADAM 12 expression was very low in cultured endothelial cells, but was significantly increased by cytokine stimulation. In parallel, the shed form of VE-cadherin was elevated in such cytokine-stimulated endothelial cells, and ADAM12 siRNA knockdown reduced cytokine-induced shedding of VE-cadherin. In conclusion, our data demonstrate a role for ADAM12 in ectodomain shedding of several membrane-anchored endothelial proteins. We speculate that this process may have importance in tumour neovascularization or/and tumour-cell extravasation.
Biochemical Journal 03/2013; · 4.90 Impact Factor
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Journal of Histochemistry and Cytochemistry 11/2012; · 2.72 Impact Factor
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ABSTRACT: Integrins are heterodimeric transmembrane receptors regulating cell-cell and cell-extracellular matrix interactions. Of the 24 integrin heterodimers identified in humans, α9β1 integrin is one of the least studied. α9, together with α4, comprise a more recent evolutionary sub-family of integrins that is only found in vertebrates. Since α9 was thought to have similar functions as α4, due to many shared ligands, it was a rather overlooked integrin until recently, when its importance for survival after birth was highlighted upon investigation of the α9 knockout mouse. α9β1 is expressed on a wide variety of cell types, interacts with many ligands for example fibronectin, tenascin-C and ADAM12, and has been shown to have important functions in processes such as cell adhesion and migration, lung development, lymphatic and venous valve development, and in wound healing. This has sparked an interest to investigate α9β1-mediated signaling and its regulation. This review gives an overview of the recent progress in α9β1-mediated biological and pathological processes, and discusses its potential as a target for cancer diagnosis and therapy.
Advances in biological regulation. 05/2012; 52(2):326-39.
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ABSTRACT: Collapsin response mediator protein 2 (CRMP-2) is known as a regulator of neuronal polarity and differentiation through microtubule assembly and trafficking. Here, we show that CRMP-2 is ubiquitously expressed and a splice variant (CRMP-2L), which is expressed mainly in epithelial cells among nonneuronal cells, regulates myosin II-mediated cellular functions, including cell migration. While the CRMP-2 short form (CRMP-2S) is recognized as a substrate of the Rho-GTP downstream kinase ROCK in neuronal cells, a CRMP-2 complex containing 2L not only bound the catalytic domain of ROCK II through two binding domains but also trapped and inhibited the kinase. CRMP-2L protein levels profoundly affected haptotactic migration and the actin-myosin cytoskeleton of carcinoma cells as well as nontransformed epithelial cell migration in a ROCK activity-dependent manner. Moreover, the ectopic expression of CRMP-2L but not -2S inhibited fibronectin matrix assembly in fibroblasts. Underlying these responses, CRMP-2L regulated the kinase activity of ROCK II but not ROCK I, independent of GTP-RhoA levels. This study provides a new insight into CRMP-2 as a controller of myosin II-mediated cellular functions through the inhibition of ROCK II in nonneuronal cells.
Molecular and cellular biology 03/2012; 32(10):1788-804. · 6.06 Impact Factor
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ABSTRACT: A recently identified breast cancer-associated mutation in the metalloprotease ADAM12 alters a potential dileucine trafficking signal, which could affect protein processing and cellular localization. ADAM12 belongs to the group of A Disintegrin And Metalloproteases (ADAMs), which are typically membrane-associated proteins involved in ectodomain shedding, cell-adhesion, and signaling. ADAM12 as well as several members of the ADAM family are over-expressed in various cancers, correlating with disease stage. Three breast cancer-associated somatic mutations were previously identified in ADAM12, and two of these, one in the metalloprotease domain and another in the disintegrin domain, were investigated and found to result in protein misfolding, retention in the secretory pathway, and failure of zymogen maturation. The third mutation, p.L792F in the ADAM12 cytoplasmic tail, was not investigated, but is potentially significant given its location within a di-leucine motif, which is recognized as a potential cellular trafficking signal. The present study was motivated both by the potential relevance of this documented mutation to cancer, as well as for determining the role of the di-leucine motif in ADAM12 trafficking. Expression of ADAM12 p.L792F in mammalian cells demonstrated quantitatively similar expression levels and zymogen maturation as wild-type (WT) ADAM12, as well as comparable cellular localizations. A cell surface biotinylation assay demonstrated that cell surface levels of ADAM12 WT and ADAM12 p.L792F were similar and that internalization of the mutant occurred at the same rate and extent as for ADAM12 WT. Moreover, functional analysis revealed no differences in cell proliferation or ectodomain shedding of epidermal growth factor (EGF), a known ADAM12 substrate between WT and mutant ADAM12. These data suggest that the ADAM12 p.L792F mutation is unlikely to be a driver (cancer causing)-mutation in breast cancer.
PLoS ONE 01/2012; 7(5):e37628. · 4.09 Impact Factor
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ABSTRACT: Invadopodia are dynamic actin structures at the cell surface that degrade extracellular matrix and act as sites of signal transduction. The biogenesis of invadopodia, including the mechanisms regulating their formation, composition, and turnover is not entirely understood. Here, we demonstrate that antibody ligation of ADAM12, a transmembrane disintegrin and metalloprotease, resulted in the rapid accumulation of invadopodia with extracellular matrix-degrading capacity in epithelial cells expressing the αvβ3 integrin and active c-Src kinase. The induction of invadopodia clusters required an intact c-Src interaction site in the ADAM12 cytoplasmic domain, but was independent of the catalytic activity of ADAM12. Caveolin-1 and transmembrane protease MMP14/MT1-MMP were both present in the ADAM12-induced clusters of invadopodia, and cholesterol depletion prevented their formation, suggesting that lipid-raft microdomains are involved in the process. Importantly, our data demonstrate that ADAM12-mediated ectodomain shedding of epidermal growth factor receptor ligands can occur within these invadopodia. Such localized growth factor signalling offers an interesting novel biological concept highly relevant to the properties of carcinoma cells, which often show upregulated ADAM12 and β3 integrin expression, together with high levels of c-Src kinase activity.
Experimental Cell Research 10/2010; 317(2):195-209. · 3.58 Impact Factor
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ABSTRACT: The disintegrin and metalloprotease ADAM12 has important functions in normal physiology as well as in diseases, such as cancer. Little is known about how ADAM12 confers its pro-tumorigenic effect; however, its proteolytic capacity is probably a key component. Thus selective inhibition of ADAM12 activity may be of great value therapeutically and as an investigative tool to elucidate its mechanisms of action. We have previously reported the inhibitory profile of TIMPs (tissue inhibitor of metalloproteinases) against ADAM12, demonstrating in addition to TIMP-3, a unique ADAM-inhibitory activity of TIMP-2. These findings strongly suggest that it is feasible to design a TIMP mutant selectively inhibiting ADAM12. With this purpose, we characterized the molecular determinants of the ADAM12-TIMP complex formation as compared with known molecular requirements for TIMP-mediated inhibition of ADAM17/TACE (tumour necrosis factor alpha-converting enzyme). Kinetic analysis using a fluorescent peptide substrate demonstrated that the molecular interactions of N-TIMPs (N-terminal domains of TIMPs) with ADAM12 and TACE are for the most part comparable, yet revealed strikingly unique features of TIMP-mediated ADAM12 inhibition. Intriguingly, we found that removal of the AB-loop in N-TIMP-2, which is known to impair its interaction with TACE, resulted in increased affinity to ADAM12. Importantly, using a cell-based epidermal growth factor-shedding assay, we demonstrated for the first time an inhibitory activity of TIMPs against the transmembrane ADAM12-L (full-length ADAM12), verifying the distinctive inhibitory abilities of N-TIMP-2 and engineered N-TIMP-2 mutants in a cellular environment. Taken together, our findings support the idea that a distinctive ADAM12 inhibitor with future therapeutic potential can be designed.
Biochemical Journal 08/2010; 430(1):79-86. · 4.90 Impact Factor
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ABSTRACT: Cell surface integrins are the primary receptors for cell migration on extracellular matrix, and exist in several activation states regulated in part by ectodomain conformation. The alpha9 integrin subunit, which pairs only with beta1, has specific roles in the immune system and may regulate cell migration. Melanoma cells express abundant alpha9beta1 integrin, and its role in cell migration was assessed. Ligands derived from Tenascin-C and ADAM12 supported alpha9beta1 integrin-mediated cell attachment and GTP-Rac dependent migration, but not focal adhesion formation. Manganese ions induced alpha9beta1 integrin- and Rho kinase-dependent focal adhesion and stress fibre formation, suggesting that the activation status of alpha9beta1 integrin was altered. The effect of manganese ions in promoting focal adhesion formation was reproduced by beta1 integrin activating antibody. The alpha9beta1 integrin translocated to focal adhesions, where active beta1 integrin was also detected by conformation-specific antibodies. Focal adhesion assembly was commensurate with reduced cell migration. Endogenous alpha9beta1 integrin-mediated adhesion was sensitive to the PP1 chemical inhibitor and an inhibitor of endosomal vesicle recycling, but not inhibitors of protein kinase C or the small GTPase Rho. Our results demonstrated that although alpha9beta1 integrin can induce and localise to focal adhesions in a high activation state, its intermediate activity state normally supports cell adhesion consistent with migration.
Experimental Cell Research 09/2009; 315(19):3312-24. · 3.58 Impact Factor
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ABSTRACT: Tetranectin was originally purified from human serum on the basis of plasminogen kringle 4-binding properties. Tetranectin enhances plasminogen activation by a tissue-type plasminogen activator so that it has been suggested to play a role in tissue remodeling. We have generated mice with a targeted disruption of the tetranectin gene to elucidate the biological function of tetranectin. In this study, we showed that wound healing was markedly delayed in tetranectin-null mice compared with wild-type mice. A single full-thickness incision was made in the dorsal skin. By 14 days after the incision, the wounds fully healed in all wild-type mice based on the macroscopic closure; in contrast, the progress of wound healing in the tetranectin null mice appeared to be impaired. In histological analysis, wounds of wild-type mice showed complete reepithelialization and healed by 14 days after the incision. However, those of tetranectin-null mice never showed complete reepithelialization at 14 days. At 21 days after the injury, the wound healed and was covered with an epidermis. These results supported the fact that tetranectin may play a role in the wound healing process.
Wound Repair and Regeneration 02/2009; 17(1):108-12. · 2.91 Impact Factor
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ABSTRACT: The disintegrin and metalloproteases (ADAMs) are emerging as therapeutic targets in human disease, but specific drug design is hampered by potential redundancy. Unlike other metzincins, ADAM prodomains remain bound to the mature enzyme to regulate activity. Here ADAM12, a protease that promotes tumor progression and chondrocyte proliferation in osteoarthritic cartilage, is shown to possess a prodomain/catalytic domain cationic molecular switch, regulated by exogenous heparan sulfate and heparin but also endogenous cell surface proteoglycans and the polyanion, calcium pentosan polysulfate. Sheddase functions of ADAM12 are regulated by the switch, as are proteolytic functions in placental tissue and sera of pregnant women. Moreover, human heparanase, an enzyme also linked to tumorigenesis, can promote ADAM12 sheddase activity at the cell surface through cleavage of the inhibitory heparan sulfate. These data present a novel concept that might allow targeting of ADAM12 and suggest that other ADAMs may have specific regulatory activity embedded in their prodomain and catalytic domain structures.
Journal of Biological Chemistry 10/2008; 283(46):31920-32. · 4.77 Impact Factor
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ABSTRACT: The ADAMs (a disintegrin and metalloproteases) are an important class of enzymes in the regulation of human disease. The pro domains of ADAMs are responsible for the latency and secretion of mature enzymes. Unlike other metzincins, ADAM pro domains remain bound to the mature enzyme after secretion. To understand the functions of human ADAM pro domains and to determine three-dimensional structures, we have screened promising targets for expression and purification properties when using Escherichia coli as the host. The pro domain of ADAM22 (ADAM22-P) expressed in E. coli was folded, as determined by CD and NMR spectroscopy. An ADAM22-P fragment encoding residues 26-199 could be expressed in high amounts, remained soluble above 1 mM, and was suitable for structural studies by NMR spectroscopy. CD spectroscopy and predictions suggest that the secondary structure in ADAM22-P consists of beta-strands. Furthermore, our data indicate that the pro domains of ADAMs are expressed as two subdomains. The most N-terminal subdomain (ADAM22-P(N)) was found to be susceptible to proteolysis and was required for folding stability of the second subdomain (ADAM22-P(C)).
Protein Expression and Purification 07/2008; 61(2):175-83. · 1.59 Impact Factor
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ABSTRACT: Human ADAM12 (a disintegrin and metalloproteinase) is a multidomain zinc metalloproteinase expressed at high levels during development and in human tumors. ADAM12 exists as two splice variants: a classical type 1 membrane-anchored form (ADAM12-L) and a secreted splice variant (ADAM12-S) consisting of pro, catalytic, disintegrin, cysteine-rich, and EGF domains. Here we present a novel activity of recombinant ADAM12-S and its domain deletion mutants on S-carboxymethylated transferrin (Cm-Tf). Cleavage of Cm-Tf occurred at multiple sites, and N-terminal sequencing showed that the enzyme exhibits restricted specificity but a consensus sequence could not be defined as its subsite requirements are promiscuous. Kinetic analysis revealed that the noncatalytic C-terminal domains are important regulators of Cm-Tf activity and that ADAM12-PC consisting of the pro domain and catalytic domain is the most active on this substrate. It was also observed that NaCl inhibits ADAM12. Among the tissue inhibitors of metalloproteinases (TIMP) examined, the N-terminal domain of TIMP-3 (N-TIMP-3) inhibits ADAM12-S and ADAM12-PC with low nanomolar Ki(app) values while TIMP-2 inhibits them with a slightly lower affinity (9-44 nM). However, TIMP-1 is a much weaker inhibitor. N-TIMP-3 variants that lack MMP inhibitory activity but retained the ability to inhibit ADAM17/TACE failed to inhibit ADAM12. These results indicate unique enzymatic properties of ADAM12 among the members of the ADAM family of metalloproteinases.
Biochemistry 02/2008; 47(2):537-47. · 3.42 Impact Factor
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ABSTRACT: ADAM12 belongs to the large family of ADAMs (a disintegrin and metalloproteases) and possesses extracellular metalloprotease and cell-binding functions, as well as intracellular signaling capacities. Interest in ADAM12 has increased recently because its expression is related to tumor progression and it is a potential biomarker for breast cancer. It is therefore important to understand ADAM12's functions. Many cellular roles for ADAM12 have been suggested. It is an active metalloprotease, and has been implicated in insulin-like growth factor (IGF) receptor signaling, through cleavage of IGF-binding proteins, and in epidermal growth factor receptor (EGFR) pathways, via ectodomain shedding of membrane-tethered EGFR ligands. These proteolytic events may regulate diverse cellular responses, such as altered cell differentiation, proliferation, migration, and invasion. ADAM12 may also regulate cell-cell and cell-extracellular matrix contacts through interactions with cell surface receptors - integrins and syndecans - potentially influencing the actin cytoskeleton. Moreover, ADAM12 interacts with several cytoplasmic signaling and adaptor molecules through its intracellular domain, thereby directly transmitting signals to or from the cell interior. These ADAM12-mediated cellular effects appear to be critical events in both biological and pathological processes. This review presents current knowledge on ADAM12 functions gained from in vitro and in vivo observations, describes ADAM12's role in both normal physiology and pathology, particularly in cancer, and discusses important areas for future investigation.
The International Journal of Biochemistry & Cell Biology 02/2008; 40(9):1685-702. · 4.63 Impact Factor
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ABSTRACT: Muscular dystrophies are characterized by insufficient restoration and gradual replacement of the skeletal muscle by fat and connective tissue. ADAM12 has previously been shown to alleviate the pathology of young dystrophin-deficient mdx mice, a model for Duchenne muscular dystrophy. The observed effect of ADAM12 was suggested to be mediated via a membrane-stabilizing up-regulation of utrophin, alpha7B integrin, and dystroglycans. Ectopic ADAM12 expression in normal mouse skeletal muscle also improved regeneration after freeze injury, presumably by the same mechanism. Hence, it was suggested that ADAM12 could be a candidate for nonreplacement gene therapy of Duchenne muscular dystrophy. We therefore evaluated the long-term effect of ADAM12 overexpression in muscle. Surprisingly, we observed loss of skeletal muscle and accelerated fibrosis and adipogenesis in 1-year-old mdx mice transgenically overexpressing ADAM12 (ADAM12(+)/mdx mice), even though their utrophin levels were mildly elevated compared with age-matched controls. Thus, membrane stabilization was not sufficient to provide protection during prolonged disease. Consequently, we reinvestigated skeletal muscle regeneration in ADAM12 transgenic mice (ADAM12(+)) after a knife cut lesion and observed that the regeneration process was significantly impaired. ADAM12 seemed to inhibit the satellite cell response and delay myoblast differentiation. These results discourage long-term therapeutic use of ADAM12. They also point to impaired regeneration as a possible factor in development of muscular dystrophy.
American Journal Of Pathology 12/2007; 171(5):1599-607. · 4.89 Impact Factor
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ABSTRACT: ADAM 12 is a placenta-derived glycoprotein that is involved in growth and differentiation. The maternal serum concentration of ADAM 12 is a potential first-trimester maternal serum marker of Down syndrome (DS). Here we examine the potential of ADAM 12 as a second-trimester maternal serum marker of DS.
The concentration of ADAM 12 was determined in gestational week 14-19 in 88 DS pregnancies and 341 matched control pregnancies. Medians of normal pregnancies were established by polynomial regression and the distribution of log(10) MoM ADAM 12 values in DS pregnancies and controls determined. Correlations with alpha-fetoprotein (AFP) and free beta-human chorionic gonadotrophin (free beta-hCG) were established and used to model the performance of maternal serum screening with ADAM 12 in combination with other second-trimester serum markers.
The ADAM 12 maternal serum concentration was significantly increased with a median MoM of 1.85 and a mean log(10) MoM (SD) of 0.268 (0.2678) compared to a mean log(10) MoM (SD) of 0.013 (0.4318) in controls. ADAM 12 correlated with maternal weight and ethnicity (with the serum concentration increased in Afro-Caribbeans), but neither with maternal age nor gestational age, and only marginally with AFP (r(DS) = 0.078, r(controls) = 0.093) and free beta-hCG (r(DS) = 0.073, r(controls) = 0.144. The increase in detection rate-for a false positive rate of 5%--by adding ADAM 12 to the double test (AFP + free beta-hCG) was 4%, similar to that of adding uE3 to the double test.
ADAM 12 is an efficient second-trimester marker for DS. Further studies should be conducted to determine whether it may be a useful additional or alternative marker to those currently used in the second-trimester.
Prenatal Diagnosis 08/2007; 27(7):611-5. · 2.11 Impact Factor
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ABSTRACT: We have previously found ADAM12, a disintegrin and metalloprotease, to be an interesting biomarker for breast cancer. The purpose of this study was to determine the gene and protein expression profiles of ADAM12 in different grades and stages of bladder cancer.
ADAM12 gene expression was evaluated in tumors from 96 patients with bladder cancer using a customized Affymetrix GeneChip. Gene expression in bladder cancer was validated using reverse transcription-PCR, quantitative PCR, and in situ hybridization. Protein expression was evaluated by immunohistochemical staining on tissue arrays of bladder cancers. The presence and relative amount of ADAM12 in the urine of cancer patients were determined by Western blotting and densitometric measurements, respectively.
ADAM12 mRNA expression was significantly up-regulated in bladder cancer, as determined by microarray analysis, and the level of ADAM12 mRNA correlated with disease stage. Reverse transcription-PCR, quantitative PCR, and in situ hybridization validated the gene expression results. Using immunohistochemistry, we found ADAM12 protein expression correlated with tumor stage and grade. Finally, ADAM12 could be detected in the urine by Western blotting; ADAM12 was present in higher levels in the urine from patients with bladder cancer compared with urine from healthy individuals. Significantly, following removal of tumor by surgery, in most bladder cancer cases examined, the level of ADAM12 in the urine decreased and, upon recurrence of tumor, increased.
ADAM12 is a promising biomarker of bladder cancer.
Clinical Cancer Research 01/2007; 12(24):7359-68. · 7.74 Impact Factor
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ABSTRACT: A Disintegrin And Metalloprotease 12 (ADAM 12) is a glycoprotein synthesised by placenta and it has been shown to be a potential first-trimester maternal serum marker for Down syndrome (DS) in two small series. Here we analyse further, the potential of ADAM 12 as a marker for DS in a large collection of first-trimester serum samples.
The concentration of ADAM 12 was determined in 10-14-week pregnancy sera from 218 DS pregnancies and 389 gestational age-matched control pregnancies, which had been collected as part of routine prospective first-trimester screening programs (DS = 105) or as part of previous research studies (DS = 113). ADAM 12 was measured using a semi-automated time resolved immunofluorometric assay and median values for normal pregnancies were established by polynomial regression. These medians were then used to determine population distribution parameters for DS and normal pregnancy groups. Correlation with previously established PAPP-A and free beta-hCG multiple of the medians (MoMs) and delta nuchal translucency (NT) were determined and used to model the performance of first-trimester screening with ADAM 12 in combination with other first-trimester markers at various time periods across the first trimester. The benefits of a contingent testing model incorporating early measurement of PAPP-A and ADAM 12 were also explored.
The maternal serum concentration of ADAM 12 was significantly reduced (p = 0.0049) with an overall median MoM of 0.79 in the DS cases and a log(10) MoM SD of 0.3734 in the DS cases and 0.3353 in the controls. There was a significant correlation of ADAM 12 MoM in DS cases with gestational age (r = 0.375) and the median MoM increased from 0.50 at 10-11 weeks to 1.38 at 13 weeks. ADAM 12 was correlated with maternal weight (r(controls) = 0.283), PAPP-A (r(controls) = 0.324, r(DS) = 0.251) but less so with free beta-hCG (r(controls) = 0.062, r(DS) = 0.049) and delta NT (r(controls) = 0.110, r(DS) = 0.151). ADAM 12 was significantly (p = 0.026) lower in smokers (0.87 vs 1.00) and elevated in Afro-Caribbean women compared to Caucasian women (1.34 vs 1.00). Population modelling using parameters from this and an earlier study showed that a combination of ADAM 12 and PAPP-A measured at 8-9 weeks and combined with NT and free beta-hCG measured at 12 weeks could achieve a detection rate of 97% at a 5% false-positive rate or 89% at a 1% false-positive rate. PAPP-A and ADAM 12 alone at 8-9 weeks could identify 91% of cases at a 5% false-positive rate. Using this as part of a contingent-screening model to select an intermediate risk group of women for NT and free beta-hCG at 11-12 weeks would enable the detection of 92% of cases with a 1% false-positive rate at a cost of providing NT and free beta-hCG for 6% of women with 94% of women having completed screening by the 10th week of pregnancy.
ADAM 12 in early first trimester is a very efficient marker of DS. In combination with existing markers, it offers enhanced screening efficiency in a two-stage sequential first-trimester screening program or in a contingent-screening model, which may have benefits in health economies where universal access to high quality ultrasound is difficult. More data on early first-trimester cases with DS are required to establish more secure population parameters by which to assess further the validity of these models.
Prenatal Diagnosis 11/2006; 26(10):973-9. · 2.11 Impact Factor
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ABSTRACT: Maternal serum ADAM12 is reduced, on average, in early first-trimester Down and Edwards' syndrome pregnancies but the extent of reduction declines with gestation. Here we study levels at 9-12 weeks when the marker might be used concurrently with other established markers.
Samples from 16 Down and 2 Edwards' syndrome cases were retrieved from storage and tested together with 313 unaffected singleton pregnancies using a semi-automated time-resolved immuno-fluorometric assay. Results were expressed in multiples of the gestation-specific median (MoM) based on regression.
The median in Down syndrome was 0.94 MoM with a 10th-90th centile range of 0.22-1.63 MoM compared with 1.00 and 0.33-2.24 MoM in unaffected controls (P = 0.21, one-side Wilcoxon Rank Sum Test). The two Edwards' syndrome cases had values 0.31 and 2.17 MoM.
ADAM12 cannot be used concurrently with other markers in the late first trimester. However, it does have the potential to be used earlier in pregnancy either concurrently with other early markers or in a sequential or contingent protocol. More data will be required to reliably predict the performance of either approach.
Prenatal Diagnosis 09/2006; 26(8):689-91. · 2.11 Impact Factor
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ABSTRACT: ADAM12-S transgenic mice exhibit a pronounced increase in the length of bones, such as femur, tibia, and vertebrae. The effect of ADAM12-S on longitudinal bone growth involves the modulation of chondrocyte proliferation and maturation, likely through proteolytic activities and altered cell-extracellular matrix interactions in the growth plate.
The disintegrin and metalloprotease ADAM12 is expressed in both osteoblasts and osteoclasts, suggesting a regulatory role of ADAM12 in bone. However, thus far, no in vivo function of ADAM12 in the skeleton has been reported.
Transgenic mice expressing the secreted form of human ADAM12, ADAM12-S, or a truncated metalloprotease-deficient form of ADAM12-S in the circulation were used to study the effects of ADAM12 on the skeleton. In addition, murine chondrocyte cultures were used to study the effect of ADAM12-S on cell-extracellular matrix interactions.
ADAM12-S transgenic mice exhibit increased longitudinal bone growth. The increased bone length is progressive and age dependent, with a maximum increase of 17% seen in the femur from 6-month-old transgenic mice. The effect is gene dose dependent, being more pronounced in mice expressing higher levels of the transgene than in a lower-expressing line. Histological analysis revealed no alterations in the growth plate organization, but mean growth plate width was increased. Both the cellular incorporation of bromodeoxyuridine and the width of the collagen type X-positive hypertrophic zone were increased in the growth plate of ADAM12-S transgenic mice. Importantly, mice expressing a truncated form of ADAM12-S that lacked the pro- and metalloprotease domains showed no alterations in bone length, suggesting that protease activity is required for the ADAM12-S effect. In vitro studies showed that ADAM12-S inhibits chondrocyte adhesion to fibronectin and collagen type II.
ADAM12-S stimulates bone growth in mice by modulating chondrocyte proliferation and maturation through mechanisms probably involving both metalloprotease and adhesion activities.
Journal of Bone and Mineral Research 09/2006; 21(8):1288-96. · 6.37 Impact Factor
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ABSTRACT: The ADAMs (a disintegrin and metalloprotease) comprise a family of multidomain proteins with metalloprotease, cell adhesion, and signaling activities. Human ADAM12, which is implicated in diseases such as cancer, is expressed in two splice forms, the transmembrane ADAM12-L and the shorter and soluble ADAM12-S. ADAM12 is synthesized as a zymogen with the prodomain keeping the metalloprotease inactive through a cysteine-switch mechanism. Maturation and activation of the protease involves the cleavage of the prodomain in the trans-Golgi or possibly at the cell surface by a furin-peptidase. The aim of the present study was to determine the fate of the prodomain following furin cleavage. Here we demonstrate that, following cleavage of the human ADAM12-S prodomain in the trans-Golgi by a furin-peptidase, the prodomain remains non-covalently associated with the mature molecule. Accordingly, both the 68-kDa mature form of ADAM12-S and the 25-kDa prodomain could be detected using domain-specific antisera in immunoprecipitation and Western blot analyses of human serum ADAM12 and purified recombinant human ADAM12. Using electron microscopy after negative staining we have furthermore obtained the first visualization of a full-length ADAM molecule, human ADAM12-S, and report that it appears to be a compact clover composed of four globular domains, one of which is the prodomain. Finally, our data demonstrate that the presence of the metalloprotease domain appears to be sufficient for the prodomain to remain associated with the mature ADAM12-S. Thus, we conclude that the prodomain of human ADAM12-S is an integral domain of the mature molecule and as such might have specific biological functions in the extracellular space.
Journal of Biological Chemistry 05/2006; 281(14):9418-22. · 4.77 Impact Factor
