Human ADAM12 Research Articles

Structural and network analysis of ADAM9 and ADAM10 and its transcript expression in the male reproductive tract of Bos Taurus

A disintegrin and metalloproteinases (ADAMs) are a family of proteins expressed as transmembrane and secreted proteins in tissues. This study investigated the expression of glycoproteins and transcripts of ADAM9 and ADAM10 in different regions of the bovine male reproductive tract (MRT). Fresh bovine samples were collected from the testis, epididymis, and vas deferens of MRT for this study. Special stains were utilized for identifying glycoproteins depending on the type of mucopolysaccharides in the seminiferous tubules of the testis and epithelial cells of the epididymis and vas deferens. Quantitative real-time PCR (qPCR) was used to assess the mRNA concentrations of ADAMs9 and 10. Additionally, structural and network analysis was performed to investigate the similarity between human and bovine ADAM9 and ADAM10. Variable glycoprotein (acidic and neutral mucopolysaccharides) expression was observed in the seminiferous tubules of the testis and epithelial cells of the epididymis and vas deferens. ADAM9 and 10 mRNA were detected in the testis epididymis and vas deferens, with ADAM9 expression being significantly higher than ADAM10 mRNA expression in the testis and tail of epididymis. Significant similarity between the protein sequence of human and bovine ADAM9 (85.75%) and ADAM10 (96.66%) was observed, while the similarity between protein sequence of ADAM 9 and ADAM10 in humans and bovine was <26%. Bovine ADAM9 showed 4 binding sites, while bovine ADAM10, human ADAM9, and human ADAM10 showed 7 binding pockets, each with considerable variations in the affinity of specific antibody sequences to these binding pockets. Network analysis confirmed that ADAM9 and ADAM10 have critical roles in physiological processes involving cell migration, protease activity, and secretase-related functions. In addition, they have large numbers of hydrogen bonds to most other members of the ADAM family. Our study reports similarities in the expression of glycoproteins and ADAM9 and ADAM10 mRNA in the MRT of Bos Taurus. Structural and network analysis of ADAM9 and ADAM10 suggested functional similarities in these proteins, which are likely to be in facilitating spermatogenesis, transcervical sperm migration, egg-sperm fusion, and fertilization. Further, the similarity between human and bovine ADAM9 and ADAM10 proteins suggests that bovine sperms can be considered as a model system for comparative medicine studies.

Abstract C111: A novel human monoclonal antibody targeting active ADAM10 demonstrates anti-tumor effects in colorectal cancer

Abstract Colorectal cancer (CRC) is the third most diagnosed cancer in the USA and accounts for more than 600,000 deaths annually worldwide, primarily due to relapse with highly aggressive, chemo-resistant disease characterized by poorly differentiated cancer cells with stem cell-like properties. A common signature of these chemo-resistant tumors is dysregulation of Notch receptor signaling, as well as upregulation of its metalloprotease activator, ADAM10. Although small molecule inhibition of either Notch or ADAM10 has been shown to produce potent anti-tumor effects, these therapeutic strategies have failed in clinical trials primarily due to systemic toxicities, especially cytotoxic effects on the gastrointestinal tract and musculoskeletal system, highlighting the need for development of more targeted approaches. We have previously demonstrated that ADAM10 predominantly exists in an inhibited state in normal tissues but is activated in tumor cells through a conformational change in the extracellular domain, thus providing a potential target for tumor-specific modulation of ADAM10 activity. Here, we look to characterize a novel human monoclonal antibody agent (1H5) that selectively targets an exposed extracellular region of activated ADAM10 on tumor cells. We previously demonstrated that treatment with a murine version of the antibody (8C7), specific for the activated form of both mouse and human ADAM10, conferred a significant reduction in tumor burden against human CRC cell lines in cell culture and transplants in xenograft models, and relapse was prevented when 8C7 was combined with chemotherapy. Here, we demonstrate that the 1H5 monoclonal antibody effectively reduces cell viability in numerous colorectal cancer cell lines in vitro and induces marked tumor regression in established xenograft models through inhibition of Notch signaling. Through the use of additional genetic tools combined with in vitro and in vivo models, our preclinical study aims to fully evaluate 1H5 as novel therapeutic agent to treat aggressive colorectal cancer. We aim to propel this novel agent toward clinical-stage development. Citation Format: Pargol Mashati, Dan Sun, Eduardo Garcia Reino, Jessica A. Blandino, Ben Mason, Nayanendu Saha, Dimitar B. Nikolov, Prem Premsrirut. A novel human monoclonal antibody targeting active ADAM10 demonstrates anti-tumor effects in colorectal cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C111.

ADAM10 mediates shedding of carbonic anhydrase IX ectodomain non‑redundantly to ADAM17.

Carbonic anhydrase IX (CA IX) is a transmembrane enzyme participating in adaptive responses of tumors to hypoxia and acidosis. CA IX regulates pH, facilitates metabolic reprogramming, and supports migration, invasion and metastasis of cancer cells. Extracellular domain (ECD) of CA IX can be shed to medium and body fluids by a disintegrin and metalloproteinase (ADAM) 17. Here we show for the first time that CA IX ECD shedding can be also executed by ADAM10, a close relative of ADAM17, via an overlapping cleavage site in the stalk region of CA IX connecting its exofacial catalytic site with the transmembrane region. This finding is supported by biochemical evidence using recombinant human ADAM10 protein, colocalization of ADAM10 with CA IX, ectopic expression of a dominant‑negative mutant of ADAM10 and RNA interference‑mediated suppression of ADAM10. Induction of the CA IX ECD cleavage with ADAM17 and/or ADAM10 activators revealed their additive effect. Similarly, additive effect was observed with an ADAM17‑inhibiting antibody and an ADAM10‑preferential inhibitor GI254023X. These data indicated that ADAM10 is aCA IX sheddase acting on CA IX non‑redundantly to ADAM17.

Identification of the extracellular metallo-endopeptidases ADAM and ADAMTS in the yellow fever mosquito Aedes aegypti

The mosquito Aedes aegypti is a major vector for dengue, Zika, yellow fever, and chikungunya (CHIKV) viruses, which cause significant morbidity and mortality among human populations in the tropical regions of the world. Following ingestion of a viremic bloodmeal from a vertebrate host, an arbovirus needs to productively infect the midgut epithelium of the mosquito. De novo synthesized virions then exit the midgut by traversing the surrounding basal lamina (BL) in order to disseminate to secondary tissues and infect those. Once the salivary glands are infected, the virus is transmitted to a vertebrate host along with saliva released during probing of the mosquito. Midgut tissue distention due to bloodmeal ingestion leads to remodeling of the midgut structure and facilitates virus dissemination from the organ. Previously, we described the matrix-metalloproteinases (MMP) of Ae. aegypti as zinc ion dependent endopeptidases (Metzincins) and showed MMP activity during midgut BL rearrangement as a consequence of bloodmeal ingestion and subsequent digestion thereby affecting arbovirus dissemination from the midgut.Here we investigate the ADAM/ADAMTS of Ae. aegypti, which form another major group of multi-domain proteinases within the Metzincin superfamily and are active during extra-cellular matrix (ECM) remodeling. Seven different ADAM and five ADAMTS were identified in Ae. aegypti. The functional protein domain structures of the identified mosquito ADAM resembled those of human ADAM10, ADAM12, and ADAM17, while two of the five mosquito ADAMTS had human orthologs. Expression profiling of Ae. aegypti ADAM/ADAMTS in immature forms, whole body-females, midguts, and ovarian tissues showed transcriptional activity of the proteinases during metamorphosis, bloodmeal ingestion/digestion, and female reproduction. Custom-made antibodies to ADAM10a and ADAM12c showed that both were strongly expressed in midgut and ovarian tissues. Furthermore, transient silencing of ADAM12c significantly reduced the carcass infection rate with CHIKV at 24 h post-infection, while silencing of ADAM12a significantly increased viral titers in secondary tissues at the same time point. Our results indicate a functional specificity for several ADAM/ADAMTS in those selected mosquito tissues.

Patent Highlights April–May 2019

Patent Highlights April–May 2019

Phenotypic Diversity of Breast Cancer-Related Mutations in Metalloproteinase-Disintegrin ADAM12

Six different somatic missense mutations in the human ADAM12 gene have been identified so far in breast cancer. Five of these mutations involve highly conserved residues in the extracellular domain of the transmembrane ADAM12-L protein. Two of these extracellular mutations, D301H and G479E, have been previously characterized in the context of mouse ADAM12. Three other mutations, T596A, R612Q, and G668A, have been reported more recently, and their effects on ADAM12-L protein structure/function are not known. Here, we show that ADAM12-L bearing the G668A mutation is largely retained in the endoplasmic reticulum in its nascent, full-length form, with an intact N-terminal pro-domain. The T596A and R612Q mutants are efficiently trafficked to the cell surface and proteolytically processed to remove their pro-domains. However, the T596A mutant shows decreased catalytic activity at the cell surface, while the R612Q mutant is fully active and comparable to the wild-type ADAM12-L. The D301H and G479E mutants, consistent with the corresponding D299H and G477E mutants of mouse ADAM12 described earlier, are not proteolytically processed and do not exhibit catalytic activity at the cell surface. Among all six breast cancer-associated mutations in ADAM12-L, mutations that preserve the activity - R612Q and L792F - occur in triple-negative breast cancers, while loss-of-function mutations - D301H, G479E, T596A, and G668A - are found in non-triple negative cancers. This apparent association between the catalytic activity of the mutants and the type of breast cancer supports a previously postulated role of an active ADAM12-L in the triple negative breast cancer disease.

Abstract P2-08-05: Functional characterization of three novel breast cancer-related somatic mutations in metalloproteinase-disintegrin ADAM12

Abstract Six different somatic missense mutations in the human ADAM12 gene have been identified so far in breast cancer. Five of these mutations involve highly conserved residues in the extracellular domain of the transmembrane ADAM12-L protein. Two of these extracellular mutations, D301H and G479E, have been previously characterized in the context of mouse ADAM12. Three other mutations, T596A, R612Q, and G668A, have been reported more recently, and their effects on ADAM12-L protein structure/function are not known. Here, we show that ADAM12-L bearing the G668A mutation is largely retained in the endoplasmic reticulum in its nascent, full-length form, with an intact N-terminal pro-domain. The T596A and R612Q mutants are efficiently trafficked to the cell surface and proteolytically processed to remove their pro-domains. However, the T596A mutant shows decreased catalytic activity at the cell surface, while the R612Q mutant is fully active and comparable to the wild-type ADAM12-L. The D301H and G479E mutants, consistent with the effect of the corresponding D229H and G477E mutations in mouse ADAM12 protein described earlier, are not proteolytically processed and do not exhibit catalytic activity at the cell surface. Among all six breast cancer-associated mutations in ADAM12-L, mutations that preserve the activity - R612Q and L792F - occur in triple-negative breast cancers, while loss-of-function mutations - D301H, G479E, T596A, and G668A - are found in non-triple negative cancers. This apparent association between the catalytic activity of the mutants and the type of breast cancer supports a previously postulated role of ADAM12-L in the triple negative breast cancer disease. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-08-05.

Alternative mRNA Splicing Generates Two Distinct ADAM12 Prodomain Variants

Human ADAM12, transcript variant 1 (later on referred to as Var-1b), present in publicly available databases contains the sequence 5′-GTAATTCTG-3′ at the nucleotide positions 340–348 of the coding region, at the 3′ end of exon 4. The translation product of this variant, ADAM12-Lb, includes the three amino acid motif 114VIL116 in the prodomain. This motif is not conserved in ADAM12 from different species and is not present in other human ADAMs. Currently, it is not clear whether a shorter variant, Var-1a, encoding the protein version without the 114VIL116 motif, ADAM12-La, is expressed in human. In this work, we have established that human mammary epithelial cells and breast cancer cells express both Var-1a and Var-1b transcripts. Importantly, the proteolytic processing and intracellular trafficking of the corresponding ADAM12-La and ADAM12-Lb proteins are different. While ADAM12-La is cleaved and trafficked to the cell surface in a manner similar to ADAM12 in other species, ADAM12-Lb is retained in the ER and is not proteolytically processed. Furthermore, the relative abundance of ADAM12-La and ADAM12-Lb proteins detected in several breast cancer cell lines varies significantly. We conclude that the canonical form of transmembrane ADAM12 is represented by Var-1a/ADAM12-La, rather than Var-1b/ADAM12-Lb currently featured in major sequence databases.

ADAM10 Missense Mutations Potentiate β-Amyloid Accumulation by Impairing Prodomain Chaperone Function

The generation of Aβ, the main component of senile plaques in Alzheimer's disease (AD), is precluded by α-secretase cleavage within the Aβ domain of the amyloid precursor protein (APP). We identified two rare mutations (Q170H and R181G) in the prodomain of the metalloprotease, ADAM10, that cosegregate with late-onset AD (LOAD). Here, we addressed the pathogenicity of these mutations in transgenic mice expressing human ADAM10 in brain. In Tg2576 AD mice, both mutations attenuated α-secretase activity of ADAM10 and shifted APP processing toward β-secretase-mediated cleavage, while enhancing Aβ plaque load and reactive gliosis. We also demonstrated ADAM10 expression potentiates adult hippocampal neurogenesis, which is reduced by the LOAD mutations. Mechanistically, both LOAD mutations impaired the molecular chaperone activity of ADAM10 prodomain. Collectively, these findings suggest that diminished α-secretase activity, owing to LOAD ADAM10 prodomain mutations, leads to AD-related pathology, strongly supporting ADAM10 as a promising therapeutic target for this devastating disease.

Computational identification and experimental validation of microRNAs binding to the Alzheimer-related gene ADAM10

BackgroundMicroRNAs (miRNAs) are post-transcriptional regulators involved in numerous biological processes including the pathogenesis of Alzheimer’s disease (AD). A key gene of AD, ADAM10, controls the proteolytic processing of APP and the formation of the amyloid plaques and is known to be regulated by miRNA in hepatic cancer cell lines. To predict miRNAs regulating ADAM10 expression concerning AD, we developed a computational approach.MethodsMiRNA binding sites in the human ADAM10 3' untranslated region were predicted using the RNA22, RNAhybrid and miRanda programs and ranked by specific selection criteria with respect to AD such as differential regulation in AD patients and tissue-specific expression. Furthermore, target genes of miR-103, miR-107 and miR-1306 were derived from six publicly available miRNA target site prediction databases. Only target genes predicted in at least four out of six databases in the case of miR-103 and miR-107 were compared to genes listed in the AlzGene database including genes possibly involved in AD. In addition, the target genes were used for Gene Ontology analysis and literature mining. Finally, we used a luciferase assay to verify the potential effect of these three miRNAs on ADAM10 3'UTR in SH-SY5Y cells.ResultsEleven miRNAs were selected, which have evolutionary conserved binding sites. Three of them (miR-103, miR-107, miR-1306) were further analysed as they are linked to AD and most strictly conserved between different species. Predicted target genes of miR-103 (p-value = 0.0065) and miR-107 (p-value = 0.0009) showed significant overlap with the AlzGene database except for miR-1306. Interactions between miR-103 and miR-107 to genes were revealed playing a role in processes leading to AD. ADAM10 expression in the reporter assay was reduced by miR-1306 (28%), miR-103 (45%) and miR-107 (52%).ConclusionsOur approach shows the requirement of incorporating specific, disease-associated selection criteria into the prediction process to reduce the amount of false positive predictions. In summary, our method identified three miRNAs strongly suggested to be involved in AD, which possibly regulate ADAM10 expression and hence offer possibilities for the development of therapeutic treatments of AD.

Abstract 5285: ADAM12: A novel mediator of tumor angiogenesis

Abstract ADAM12 (a disintegrin and metalloprotease) is a member of a family of integral membrane and secreted Zn-dependent metalloproteases that have diverse roles in normal and pathological states. Human ADAM12 is expressed as two alternatively spliced forms, a membrane-anchored long form (ADAM12-L), and a short secreted form (ADAM12-S). Increased levels of ADAM12 mRNA and protein have been reported in a variety of cancers including colon, hepatocellular, lung, gastric and glioblastoma. We have previously reported that urinary ADAM12 is predictive of disease status and stage in breast cancer. We have also demonstrated that expression of ADAM12 isoforms in breast tumor cells results in a higher rate of tumor take, increased tumor size and endocrine resistance. ADAM12-S expression stimulated migration and invasion of breast tumor cells in vitro and local and distant tumor invasion in vivo. In the course of these studies, we observed that ADAM12 is upregulated in the vessels of aggressive breast tumors as compared to normal adjacent breast tissue. ADAM12-overexpressing breast tumors also displayed a higher microvascular density. Furthermore, we found that angiogenic tumors express higher levels of ADAM12 compared to their preangiogenic counterparts. The goal of the present study was to determine whether ADAM12 regulates tumor angiogenesis. Basal levels of ADAM12-L expression in HUVEC and HMVEC are relatively low, however, both ADAM12 protein and mRNA expression is significantly increased when cells are stimulated with growth factors such as VEGF, bFGF or inflammatory cytokines such as TNFα, TGFβ or IL1α. Interestingly, VEGF stimulation of endothelial cells (EC) resulted in ADAM12 protein expression and/or localization specifically along the invadopodia of these cells. Consistent with these results, we found that ADAM12 overexpression in EC resulted in significantly increased rates of migration, capillary tube formation and increased adhesion to fibronectin and type IV collagen but not laminin. In vivo studies demonstrate that ADAM12 significantly increases bFGF-mediated angiogenesis in the mouse corneal pocket assay. Taken together, our data provide evidence supporting a novel role for ADAM12 in the regulation of endothelial cell function and tumor angiogenesis. Studies to investigate the mechanism/s by which ADAM12 may regulate angiogenesis are ongoing. [The authors acknowledge the support of NIH PO1 CA045548, The Breast Cancer Research Foundation and The Simeon J. Fortin Foundation] Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5285. doi:1538-7445.AM2012-5285

Z-DNA-forming silencer in the first exon regulates human ADAM-12 gene expression

Upregulation of ADAM-12, a novel member of the multifunctional ADAM family of proteins is linked to cancer, arthritis and cardiac hypertrophy. Basal expression of ADAM-12 is very low in adult tissues but rises markedly in response to certain physiological cues, such as during pregnancy in the placenta, during development in neonatal skeletal muscle and bone and in regenerating muscle. Studies on ADAM-12 regulation have identified a highly conserved negative regulatory element (NRE) at the 5'-UTR of human ADAM-12 gene, which acts as a transcriptional repressor. The NRE contains a stretch of dinucleotide-repeat sequence that is able to adopt a Z-DNA conformation both in vitro and in vivo and interacts with hZα(ADAR1), a bona fide Z-DNA-binding protein. Substitution of the dinucleotide-repeat-element with a non-Z-DNA-forming sequence inhibited NRE function. We have detected a NRE DNA-binding protein activity in several tissues where ADAM-12 expression is low while no such activity was seen in the placenta where ADAM-12 expression is high. These observations suggest that interaction of these proteins with ADAM-12 NRE is critical for transcriptional repression of ADAM-12. We also show that the Z-DNA forming transcriptional repressor element, by interacting with these putative Z-DNA-binding proteins, is involved in the maintenance of constitutive low-level expression of human ADAM-12. Together these results provide a foundation for therapeutic down-regulation of ADAM-12 in cancer, arthritis and cardiac hypertrophy.

ADAM-15 Disintegrin-Like Domain Structure and Function

The ADAM (a disintegrin-like and metalloproteinase) proteins are a family of transmembrane cell-surface proteins with important functions in adhesion and proteolytic processing in all animals. Human ADAM-15 is the only member of the ADAM family with the integrin binding motif Arg-Gly-Asp (RGD) in its disintegrin-like domain. This motif is also found in most snake venom disintegrins and other disintegrin-like proteins. This unique RGD motif within ADAM-15 serves as an integrin ligand binding site, through which it plays a pivotal role in interacting with integrin receptors, a large family of heterodimeric transmembrane glycoproteins. This manuscript will present a review of the RGD-containing disintegrin-like domain structures and the structural features responsible for their activity as antagonists of integrin function in relation to the canonical RGD template.

Association between paternal schizophrenia and low birthweight: ADAM12 may matter

Dear Editor, I am Dr Hans-Gert Bernstein from the Department of Psychiatry, University of Magdeburg, Germany. Although it is now a well-established fact that mothers with schizophrenia are at higher risk for obstetric complications (preterm births, preeclampsia, low birthweight [LBW] and small-for-gestational-age babies), a putative paternal impact was largely ignored until recently. Now a comprehensive, population-based study in Taiwan, China has revealed that infants whose fathers had schizophrenia were much more likely to have LBW than those whose fathers did not (12.6% vs. 8.0%) 1. Unlike the situation with schizophrenic mothers, in whom inadequate prenatal care was identified as one major cause for obstetric complications 2, it remains to be established how the mental illness of the father may influence the outcome of a pregnancy. Although social factors cannot be ruled out, mainly biological factors are supposed to contribute to the increased risk of LBW of children sired by schizophrenic fathers 1. The expression of paternal genes might significantly influence placental and fetal growth development 3. The identity of such paternal factors remained largely unknown, as yet. However, from several points of view, A disintegrin and metalloprotease (ADAM)12, which in many ways may influence the outcome of a pregnancy, emerges as an interesting candidate. ADAM12, which is highly expressed in the placenta, has been proposed to be a regulator of trophoblast fusion, which is a crucial event of major importance for the preservation of a healthy pregnancy. This process takes place throughout pregnancy and is crucial for the maintenance of the syncytiotrophoblast layer, the direct border between maternal blood and fetal tissues 4. Recent evidence also suggests a prominent involvement of ADAM12 in promoting the uterine decidualization, which is characterized by the proliferation of stromal cells and their differentiation into specialized decidual cells, surrounding the implanting blastocyst 5. Proper decidualization is another prerequisite for a healthy pregnancy. Further, a truncated form of ADAM12 is released from the trophoblast into maternal blood and regulates by degradation the levels of insulin-like growth factors, which are prominently involved in the control of fetal growth and development 6. Lastly, ADAM12 is an established sheddase of placental leucine aminopeptidase (oxytocinase) 7, an enzyme critically involved in the induction of labour and hence probably having an important role in preterm births 8. Support of pathophysiological functions of ADAM12 in obstetric complications comes from observations of reduced maternal blood levels of ADAM12 in cases of small-for-gestational-age fetuses 6 and preeclampsia 9. Although there is yet no evidence for a paternal imprinting of ADAM12, a considerable paternal influence on the placental expression of this enzyme must be assumed. The possible link between ADAM12 expression/activity and genetic aspects of paternal schizophrenia is given by the location of the ADAM12 gene on human chromosome 10q26.3. This gene locus has repeatedly been linked to schizophrenia, and there is recent evidence showing that at least one SNP within the human ADAM12 gene is significantly associated with this disease (reviewed in Farkas et al. 10). Moreover, we recently could show that in postmortem brains of male and female patients with schizophrenia the cellular expression of ADAM12 is indeed significantly reduced 10. Thus, a possible link between paternal schizophrenia and LWB might be existing through reduced ADAM12 expression levels. However, unlike for other obstetric complications, a decreased ADAM12 expression during pregnancy that contributes to LWB has not been shown yet, and is thus a hypothesis worth to be tested in andrological/gynecological practice.

Reduced density of ADAM 12-immunoreactive oligodendrocytes in the anterior cingulate white matter of patients with schizophrenia

Objectives. Abnormalities of brain white matter and oligodendroglia are replicated findings in schizophrenia research. The largely oligodendroglia-associated enzyme ADAM (A disintegrin and metalloprotease) 12 might be involved in the patho-physiology of schizophrenia, because the gene coding for human ADAM12 is located on chromosome 10q26.3, a gene locus which has been linked to schizophrenia, and some of its putative substrates are altered in schizophrenia. Methods. We studied the numerical density of ADAM12 expressing oligodendrocytes in post-mortem prefrontal brains of patients with haloperidol treated, chronic schizophrenia and matched controls. Results. A significantly reduced numerical density of ADAM12 immunoreactive oligodendrocytes was found in the white matter of the anterior cingulate cortex of schizophrenic patients. Conclusions. Although the pathophysiological implications of this finding are currently unknown, it is well conveyable that reduced ADAM12 protein contributes to a deviant metabolism of some of its substrates. These substrates are either parts of important signalling cascades (EGF, betacellulin, TGF-beta) or chemical components of myelin (neurofascin-ankyrin) known to be compromised in schizophrenia.

ADAM12 localizes with c-Src to actin-rich structures at the cell periphery and regulates Src kinase activity

ADAM12 is an active metalloprotease playing an important role in tumour progression. Human ADAM12 exists in two splice variants: a long transmembrane form, ADAM12-L, and a secreted form, ADAM12-S. The subcellular localization of ADAM12-L is tightly regulated and involves intracellular interaction partners and signalling proteins. We demonstrate here a c-Src-dependent redistribution of ADAM12-L from perinuclear areas to actin-rich Src-positive structures at the cell periphery, and identified two separate c-Src binding sites in the cytoplasmic tail of ADAM12-L that interact with the SH3 domain of c-Src with different binding affinities. The association between ADAM12-L and c-Src is transient, but greatly stabilized when the c-Src kinase activity is disrupted. In agreement with this observation, kinase-active forms of c-Src induce ADAM12-L tyrosine phosphorylation. Interestingly, ADAM12-L was also found to enhance Src kinase activity in response to external signals, such as integrin engagement. Thus, we suggest that activated c-Src binds, phosphorylates, and redistributes ADAM12-L to specific sites at the cell periphery, which may in turn promote signalling mechanisms regulating cellular processes with importance in cancer.

Identification of binding peptides of the ADAM15 disintegrin domain using phage display

ADAM15 plays an important role in tumour development by interacting with integrins. In this study, we investigated the target peptides of the ADAM15 disintegrin domain. First, we successfully produced the recombinant human ADAM15 disintegrin domain (RADD) that could inhibit melanoma cell adhesion by using Escherichia coli. Second, four specific binding peptides (peptides A, B, C, and D) were selected using a phage display 12-mer peptide library. The screening protocol involved 4 rounds of positive panning on RADD and 2 rounds of subtractive selection with streptavidin. By using the BLAST software and a relevant protein database, integrin alpha v beta 3 was found to be homologous to peptide A. Synthetic peptide A had a highly inhibitory effect on RADD-integrin alpha v beta 3 binding. The results demonstrate the potential application of short peptides for disrupting high-affinity ADAM-integrin interactions.

Emphysema Mediated by Lung Overexpression of ADAM10

Cigarette smoking is the major risk factor for emphysema, a disorder of the lung parenchyma characterized by destruction of the alveolar walls. Current concepts of the pathogenesis of emphysema hold that the destruction of the lung parenchyma results, in part, from a local imbalance of proteases and antiproteases. Based on the knowledge that human alveolar macrophages express ADAM 10, a protease capable of destroying basement membrane collagen but not previously implicated in emphysema, we used adenovirus-mediated lung expression of ADAM 10 in a mouse model to assess whether an increased burden of ADAM 10 was capable of inducing emphysema. To assess this, the human ADAM 10 cDNA under control of a constitutive promoter was inserted into an adenovirus gene transfer vector (AdhADAMlO), and the vector (10(11) particle units) administered to the respiratory tract of wild type C57BI/6 mice. Lung levels of ADAM 10 mRNA and protein were upregulated following AdhADAMlO administration. After 8 weeks, quantitative morphometry of the lung parenchyma demonstrated that AdhADAMlO administration induced emphysema (mean linear intercept of 60.6 + 1.3 microm compared with 55.6 + 0.8 in mice treated with a control vector, p < 0.003). These results suggest a role of ADAM 10 in the pathogenesis of emphysema, adding to the list of proteases expressed in the lung that are capable of contributing to the development of lung destruction.

Enhancement of Recombinant Human ADAM15 Disintegrin Domain Expression Level by Releasing the Rare Codons and Amino Acids Restriction

This study was aimed at increasing the production of the recombinant human ADAM15 disintegrin domain (RADD) in Escherichia coli by releasing the rare codons and restricting amino acid residues. Three different strategies for increasing RADD production were examined: to select the suitable host strain, to optimize the rare codons, and to delete the amino acids residues. The total fusion protein glutathione-S-transferase (GST)-RADD concentration of 298 mg/l and 326 mg/l were achieved by selecting E. coli Rosetta (DE3) as the host strain and by changing GGA to GGC at the GST-RADD cassette, respectively. The RADD concentration was increased by 35.7% by eliminating the "Pro-Glu-Phe" residues at the GST-RADD junction. By combinational utilizing the preferred codon introduction and amino acid sequence optimization in E. coli Rosetta (DE3), the highest RADD concentration of 68 mg/l was achieved. The proposed strategy may provide an alternative approach for other enhanced recombinant protein production by E. coli.

ADAM15 suppresses cell motility by driving integrin α5β1 cell surface expression via Erk inactivation

Human ADAM15 is unique among the A disintegrin and metalloprotease domain (ADAM) family because of the integrin binding motif Arg–Gly–Asp (RGD) within its disintegrin domain. Integrin α5β1 has been reported to bind to ADAM15 in an RGD-dependent manner, but the biological significance of the interaction between ADAM15 and α5β1 is unknown. To characterize the effects of ADAM15 on α5β1-mediated cell adhesion and migration and elucidate the potential mechanism, CHO cells which express endogenous integrin α5β1 were transfected with human ADAM15 cDNA. ADAM15 overexpression led to enhanced cell adhesion and decreased migration on fibronectin, which were suppressed by down-regulation of integrin α5. Overexpression of ADAM15 not only increased the cell surface expression of integrin α5 but also resulted in a more clustered staining of α5 on cell surface, while the β1 subunit remained unchanged. Unexpectedly, results from immunoprecipitation and immunofluorescence indicated that ADAM15 and α5β1 integrin did not interact directly in CHO cells. We found that ADAM15 expression decreased the phosphorylation of Erk1/2. Consistently, down-regulation of Erk1/2 phosphorylation by MEK inhibitor PD98059 or siRNA against Erk1/2 enhanced the expression of α5 on cell surface. By using a B16F10 pulmonary metastasis model, we revealed that overexpression of ADAM15 significantly reduced the number of metastatic nodules on the lung. Taken together, this study reveals for the first time that ADAM15 could drive α5 integrin expression on cell surface via down-regulation of phosphorylated Erk1/2. This presents a novel mechanism by which ADAM15 regulates cell-matrix adhesion and migration.