Expression of seven members of the ADAM family in developing chicken spinal cord

The expression patterns of seven members of the ADAM (a disintegrin and metalloprotease) family, including ADAM9, ADAM10, ADAM12, ADAM13, ADAM17, ADAM22, and ADAM23, were analyzed in the developing chicken lumbar spinal cord by in situ hybridization and immunohistochemistry. Results show that each individual ADAM is expressed and regulated spatiotemporally in the lumbar cord and its surrounding tissues. ADAM9, ADAM10, ADAM22, and ADAM23 are expressed predominantly by motoneurons in the motor column and by sensory neurons in the dorsal root ganglia, each with a different expression pattern. ADAM12 and ADAM13 are mainly expressed in the meninges around the lumbar cord and in the condensed sheets of chondroblasts around the vertebrae. ADAM17 expression is strong in the ventricular layer and limited to early stages. The differential expression of the ADAMs in the lumbar cord suggests that the ADAMs play a regulatory role in development of the spinal cord. Developmental Dynamics 239:1246–1254, 2010. © 2010 Wiley‐Liss, Inc.     

Differential expression of five members of the ADAM family in the developing chicken brain

ADAMs (a disintegrin and metalloprotease) are a family of trans-membrane multi-domain metalloproteases with multiple functions. So far, more than 35 ADAM family members have been identified from mammalian and nonmammalian sources. Although some functions of ADAMs have been elucidated, their expression patterns remain poorly investigated, especially during CNS development. Here, we cloned the open reading frames or full-length cDNAs of ADAM9, ADAM10, ADAM12, ADAM22 and ADAM23 from chicken embryonic brain, analyzed their evolutionary relationship, and mapped their expression in the embryonic chicken brain by in situ hybridization for the first time. In general, each of the five ADAMs shows a spatially restricted and temporally regulated expression profile. However, the types of tissues and cells, which express each of the five ADAMs, differ from each other. ADAM9 is predominantly expressed in the choroid plexus and in the ventricular layer. ADAM10 is expressed by developing blood vessels, oligodendrocytes, and subsets of neurons and brain nuclei. ADAM12 is expressed by very few brain nuclei, cerebellar Purkinje cells, restricted regions of the neuroepithelium, and some neurons in the deep tectal layers. ADAM22 expression is strong in some brain nuclei and in the pineal gland. ADAM23 is expressed by most gray matter regions and the choroid plexus. The differential expression patterns suggest that the five ADAMs play multiple and versatile roles during brain development.     

Differential regional expression of multiple ADAMs during feather bud formation

The expression of seven members of the ADAM family was investigated by in situ hybridization in the developing feather buds of chicken. The expression profiles of the ADAMs in the cells and tissues of the feather buds differ from each other. ADAM9, ADAM10, and ADAM17 are expressed in the epidermis of the feather bud, whereas ADAM23 expression is restricted to the bud crest, with a distribution similar to that of sonic hedgehog. ADAM13 is not only expressed in the epidermis, but also in restricted regions of the dermis. Both ADAM12 and ADAM22 are expressed in the dermis of the feather bud, with an opposite mediolateral and anteroposterior polarity. Furthermore, the mRNAs of all investigated ADAMs show regional differences in their expression, for example, in the neck and in the roots of the leg and wing. These results suggest that ADAMs play a variety of roles during avian feather bud formation. Developmental Dynamics 240:2142–2152, 2011. © 2011 Wiley‐Liss, Inc.     

Regional expression of the ADAMs in developing chicken cochlea

The expression patterns of five members of the ADAM (a disintegrin and metalloprotease) family including ADAM9, ADAM10, ADAM17, ADAM22, and ADAM23 were analyzed in different anatomical structures of the developing chicken cochlea by in situ hybridization and immunohistochemistry. Results show that ADAM9, ADAM10, and ADAM17 are widely expressed in the sensory epithelium of the basilar papilla, by homogene cells, spindle‐shaped cells, and acoustic ganglion cells, and in the tegmentum vasculosum, each with a different pattern. ADAM22 expression is restricted to spindle‐shaped cells and acoustic ganglion cells, while ADAM23 is prominently expressed by hair cells and acoustic ganglion cells. Furthermore, ADAM10 protein is coexpressed with several members of the classic cadherins, including cadherin‐7, N‐cadherin, and R‐cadherin in distinct anatomical regions of the cochlea except for acoustic ganglion cells. The expression of the ADAMs in the developing cochlea suggests a contribution of the ADAMs to the development of distinct cochlear structures. Developmental Dynamics 239:2256–2265, 2010. © 2010 Wiley‐Liss, Inc.     

Cysteine-Rich Domain of Human ADAM 12 (Meltrin α) Supports Tumor Cell Adhesion

The ADAMs (A disintegrin and metalloprotease) comprise a family of membrane-anchored cell surface proteins with a putative role in cell-cell and/or cell-matrix interactions. By immunostaining, ADAM 12 (meltrin alpha) was up-regulated in several human carcinomas and could be detected along the tumor cell membranes. Because of this intriguing staining pattern, we investigated whether human ADAM 12 supports tumor cell adhesion. Using an in vitro assay using recombinant polypeptides expressed in Escherichia coli, we examined the ability of individual domains of human ADAM 12 and ADAM 15 to support tumor cell adhesion. We found that the disintegrin-like domain of human ADAM 15 supported adhesion of alphavbeta3-expressing A375 melanoma cells. In the case of human ADAM 12, however, recombinant polypeptides of the cysteine-rich domain but not the disintegrin-like domain supported cell adhesion of a panel of carcinoma cell lines. On attachment to recombinant polypeptides from the cysteine-rich domain of human ADAM 12, most tumor cell lines, such as MDA-MB-231 breast carcinoma cells, were rounded and associated with numerous actin-containing filopodia and used a cell surface heparan sulfate proteoglycan to attach. Finally, we demonstrated that authentic full-length human ADAM 12 could bind to heparin Sepharose. Together these results suggest a novel role of the cysteine-rich domain of ADAM 12 -- that of supporting tumor cell adhesion.     

Developmental expression of metalloproteases ADAM 9, 10, and 17 becomes restricted to divergent pancreatic compartments.

The A Disintegrin And Metalloprotease (ADAM) family of metalloproteases affects a variety of proteins with important roles in development and disease, including growth factors and adhesion molecules. We have analyzed the expression patterns of ADAMs 9, 10, and 17 during pancreas ontogeny. All ADAMs investigated were expressed in the pancreatic anlagen but invariably became restricted to divergent pancreatic compartments. ADAM9 and 17 became restricted to the insulin-producing beta-cells and all islet cells, respectively. During embryogenesis, ADAM10 was detected predominantly in acinar cells, but in the adult, it was localized to the cell surface membrane of both endocrine and exocrine cells. In addition to ADAM9, a potential prognostic factor for ductal cancers, we describe the expression of ADAM10 and ADAM17 in the pancreatic ductal epithelium. Altogether, the dynamic expression profile of the ADAM proteases described here may reflect a functional divergence of these as mediators of pancreas biology.     

Novel metalloprotease-disintegrin, meltrin epsilon (ADAM35), expressed in epithelial tissues during chick embryogenesis.

Members of the ADAM (a disintegrin and metalloprotease) family are involved in fertilization, morphogenesis, and pathogenesis. Their metalloprotease domains mediate limited proteolysis, including ectodomain shedding of membrane-anchored growth factors and intercellular-signaling proteins, and their disintegrin domains play regulatory roles in cell adhesion and migration. In screening for cDNAs encoding chicken ADAM proteins expressed during muscle development, we identified Meltrin epsilon as a novel member of this family. To elucidate its functions, we investigated its expression during development by using antibodies raised against its protease domain. In the somites, Meltrin epsilon protein was specifically expressed in the myotomal cells, which delaminate from the dermomyotome to form epithelial sheets. It was also found in the surface ectoderm, lens placodes, otic vesicles, and the gut epithelia. Basolateral localization of Meltrin epsilon in these epithelial cells suggests its unique roles in the organization of the epithelial tissues and development of the sensory organs and the gut.     

Expression of ADAMs (“a disintegrin and metalloprotease”) in the human lung

In view of the associations of “a disintegrin and metalloprotease” (ADAM) with respiratory diseases, we assessed the expression of various ADAMs in human lung tissue. Lung tissue was obtained from nine individuals who underwent surgery for lung cancer or underwent lung transplantation for emphysema. Also, 16HBE 14o- (human bronchial epithelial) and A549 (alveolar type II epithelium-like) cell lines were used. Immunohistochemistry was performed with antibodies recognizing different ADAM domains. The ADAMs were typically distributed over the bronchial epithelium. ADAM8 and ADAM10 were expressed diffusely in all layers of the epithelium. ADAM9, ADAM17, and ADAM19 were predominantly expressed in the apical part of the epithelium, and ADAM33 was predominantly and strongly expressed in basal epithelial cells. In smooth muscle, ADAM19 and ADAM17 were strongly expressed, as was ADAM33, though this expression was weaker. ADAM33 was strongly expressed in vascular endothelium. All ADAMs were generally expressed in inflammatory cells. The typical distribution of ADAMs in the lung, especially in the epithelium, is interesting and suggests a localized function. As most ADAMs are involved in release of (pro-) inflammatory mediators and growth factors, they may play an important role in the first line of defense and in initiation of repair events in the airways.     

Developmental regulation and neuronal expression of the cellular disintegrin ADAM11 gene in mouse nervous system

ADAM11 is the prototype member of the predominantly CNS-associated clade of the ADAM metalloprotease-disintegrins that has been implicated in neural adhesion and axon guidance. The present study describes the spatiotemporal expression pattern of the ADAM11 gene in adult and developing mouse, and identifies the cells expressing the gene. In the adult CNS, ADAM11 mRNA was present throughout the forebrain, including different cortical fields and diencephalic nuclei. In brainstem, low to moderate expression was detected in certain midbrain nuclei, while several pontine and medullary nuclei showed a very strong signal. High expression was observed in the cerebellar cortex and spinal cord. In addition, ADAM11 was expressed in ganglia of the peripheral nervous system (PNS), retinae, testes, liver, and at lower levels in epidermal and mucosal epithelia, kidney, and salivary gland. The expression was localized to neurons in all examined CNS and PNS subfields. During pre- and perinatal development, ADAM11 was differentially expressed both in the developing PNS and CNS, as well as in heart, kidney, eyes, and brown fat.The present results suggest a widespread involvement of ADAM11 in neuron-neuron or neuron-glial cell interactions during development as well as in the adult nervous system. They provide novel complementary information to recently accumulated data on CNS integrin gene expression and offer useful clues for further studies of the neural functions of ADAMs and integrins.     

The disintegrin/metalloprotease ADAM 10 is essential for Notch signalling but not for alpha-secretase activity in fibroblasts

The metalloprotease ADAM 10 is an important APP alpha-secretase candidate, but in vivo proof of this is lacking. Furthermore, invertebrate models point towards a key role of the ADAM 10 orthologues Kuzbanian and sup-17 in Notch signalling. In the mouse, this function is, however, currently attributed to ADAM 17/TACE, while the role of ADAM 10 remains unknown. We have created ADAM 10-deficient mice. They die at day 9.5 of embryogenesis with multiple defects of the developing central nervous system, somites, and cardiovascular system. In situ hybridization revealed a reduced expression of the Notch target gene hes-5 in the neural tube and an increased expression of the Notch ligand dll-1, supporting an important role for ADAM 10 in Notch signalling in the vertebrates as well. Since the early lethality precluded the establishment of primary neuronal cultures, APPs alpha generation was analyzed in embryonic fibroblasts and found to be preserved in 15 out of 17 independently generated ADAM 10-deficient fibroblast cell lines, albeit at a quantitatively more variable level than in controls, whereas a severe reduction was found in only two cases. The variability was not due to differences in genetic background or to variable expression of the alternative alpha-secretase candidates ADAM 9 and ADAM 17. These results indicate, therefore, either a regulation between ADAMs on the post-translational level or that other, not yet known, proteases are able to compensate for ADAM 10 deficiency. Thus, the observed variability, together with recent reports on tissue-specific expression patterns of ADAMs 9, 10 and 17, points to the existence of tissue-specific 'teams' of different proteases exerting alpha-secretase activity.     

Differential expression of ADAM15 and ADAM17 metalloproteases in the rat brain after severe hypobaric hypoxia and hypoxic preconditioning

The ADAMs (a disintegrin and metalloprotease) are a family of membrane-anchored glycoproteins capable of shedding a multitude of proteins from the cell surface. Although ADAMs are being considered as crucial modulators of physiological and pathophysiological processes, their roles in neuronal death/survival are largely unexplored. In the present study, changes in brain expression of ADAM15 and ADAM17 (TACE) have been quantitatively examined in rats in response to injurious severe hypoxia (SH) and in animals which acquired hypoxic tolerance through preconditioning to mild hypoxia prior SH. SH persistently up-regulated ADAM15 mRNA and protein levels in hippocampus and neocortex but not in thalamus or hypothalamus. This effect was not observed in the preconditioned rats tolerant to SH. In contrast, hippocampal levels of ADAM17 mRNA and neocortical levels of ADAM17 mRNA and protein were largely reduced following SH in non-preconditioned rats. Hypoxic preconditioning prevented down-regulation of the adam17 gene and considerably enhanced ADAM17 protein expression in hippocampus and neocortex in response to SH. The present findings implicate ADAM15 in the processes of neuronal hypoxic injury. On the other hand, these results also provide evidence for a pro-survival neuroprotective role of ADAM17 and its engagement in the process of preconditioning-induced hypoxic tolerance. The analysis of the protein levels of soluble and membrane-bound forms of APP in the neocortex and hippocampus of rats subjected to SH and SH with preconditioning has demonstrated that an increased ADAM17 expression in preconditioned animals 24h after hypoxia corresponded to a higher level of soluble form of APP and a reduction of the membrane bound fraction which reflects the role of ADAM17 in APP shedding.     

Subcellular localization and activation of ADAM proteases in the context of FasL shedding in T lymphocytes

The “A Disintegrin And Metalloproteinases” (ADAMs) form a subgroup of the metzincin endopeptidases. Proteolytically active members of this protein family act as sheddases and govern key processes in development and inflammation by regulating cell surface expression and release of cytokines, growth factors, adhesion molecules and their receptors. In T lymphocytes, ADAM10 sheds the death factor Fas Ligand (FasL) and thereby regulates T cell activation, death and effector function. Although FasL shedding by ADAM10 was confirmed in several studies, its regulation is still poorly defined. We recently reported that ADAM10 is highly abundant on T cells whereas its close relative ADAM17 is expressed at low levels and transiently appears at the cell surface upon stimulation. Since FasL is also stored intracellularly and brought to the plasma membrane upon stimulation, we addressed where the death factor gets exposed to ADAM proteases. We report for the first time that both ADAM10 and ADAM17 are associated with FasL-containing secretory lysosomes. Moreover, we demonstrate that TCR/CD3/CD28-stimulation induces a partial positioning of both proteases and FasL to lipid rafts and only the activation-induced raft-positioning results in FasL processing. TCR/CD3/CD28-induced FasL proteolysis is markedly affected by reducing both ADAM10 and ADAM17 protein levels, indicating that in human T cells also ADAM17 is implicated in FasL processing. Since FasL shedding is affected by cholesterol depletion and by inhibition of Src kinases or palmitoylation, we conclude that it requires mobilization and co-positioning of ADAM proteases in lipid raft-like platforms associated with an activation of raft-associated Src-family kinases.     

ADAM23 methylation and expression analysis in brain tumors

The ADAMs comprises a family of cell surface proteins with putative roles in cell–cell and/or cell–matrix interactions and in protease activities. In this work, we have examined the expression level and the methylation status of the 5′ upstream region of the adhesion molecule ADAM23 in two brain tumor cell lines (A172 and T98G) as well as in three primary brain tumors (one grade II astrocytoma and two meningiomas) and 15 glioblastoma xenografts. Using bisulfite sequencing we verified that the percentage of methylated dinucleotides is higher in T98G when compared to A172 and that methylation significantly correlates with ADAM23 mRNA and protein expression. However, we were unable to detect methylation and down-regulation of the ADAM23 gene in brain tumors. Together, these results indicate that ADAM23 down-regulation by methylation in brain tumors is a rare event and it may help explain why brain tumor metastases are rarely found elsewhere in the body.     

Analysis of the disintegrin-metalloproteinases family reveals ADAM29 and ADAM7 are often mutated in melanoma

We performed a mutational analysis of the 19 disintegrin-metalloproteinases (ADAMs) genes in human cutaneous metastatic melanoma and identified eight to be somatically mutated in 79 samples, affecting 34% of the melanoma tumors analyzed. Functional analysis of the two frequently mutated ADAM genes, ADAM29 and ADAM7 demonstrated that the mutations affect adhesion of melanoma cells to specific extracellular matrix proteins and in some cases increase their migration ability. This suggests that mutated ADAM genes could play a role in melanoma progression.     

The ADAMs family: coordinators of nervous system development, plasticity and repair

A disintegrin and metalloprotease (ADAM) transmembrane proteins have metalloprotease, integrin-binding, intracellular signaling and cell adhesion activities. In contrast to other metalloproteases, ADAMs are particularly important for cleavage-dependent activation of proteins such as Notch, amyloid precursor protein (APP) and transforming growth factor alpha (TGFalpha), and can bind integrins. Not surprisingly, ADAMs have been shown or suggested to play important roles in the development of the nervous system, where they regulate proliferation, migration, differentiation and survival of various cells, as well as axonal growth and myelination. On the eleventh anniversary of the naming of this family of proteins, the relatively unknown ADAMs are emerging as potential therapeutic targets for neural repair. For example, over-expression of ADAM10, one of the alpha-secretases for APP, can prevent amyloid formation and hippocampal defects in an Alzheimer mouse model. Another example of this potential neural repair role is the finding that ADAM21 is uniquely associated with neurogenesis and growing axons of the adult brain. This comprehensive review will discuss the growing literature about the roles of ADAMs in the developing and adult nervous system, and their potential roles in neurological disorders. Most excitingly, the expanding understanding of their normal roles suggests that they can be manipulated to promote neural repair in the degenerating and injured adult nervous system.