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PubMed1996

A unique gene encodes spliceoforms of the B-cell adhesion molecule cell surface glycoprotein of epithelial cancer and of the Lutheran blood group glycoprotein.

Two new members of the Ig superfamily, the Lutheran (Lu) blood group glycoprotein and the B-cell adhesion molecule (B-CAM) epithelial cancer antigen, have been recently cloned from human placenta and colon cancer HT29 cell line, respectively. Although amino acid sequences deduced from cDNA analysis suggested that B-CAM should represent an abridged form of the Lu glycoprotein lacking the last 40 amino acids of the putative cytoplasmic tail, the relationship between the genes encoding these polypeptides has not been determined. In the present report, we showed by Southern blot analysis that the Lu and B-CAM cDNAs derived from a unique LU gene which exhibited an HindIII RFLP associated with the Lua/Lub blood group polymorphism. Accordingly, in situ hybridization of the Lu cDNA probe confirmed the localization of the Lutheran blood group locus to chromosome 19 q13.2-13.3, as previously shown for a B-CAM DNA probe. Sequence comparison between cDNA and genomic PCR fragments indicated that the Lu and B-CAM transcripts previously isolated are generated through the alternative use of internal splice donor and acceptor sites within an exon located at the 3' end of the LU gene. These spliceoforms corresponded to 2.5 kb and 4.0 kb mRNA species detectable by Northern blot in all tissues and cell lines in which the LU gene is expressed; their primary structures are consistent with the presence of both the Lu and B-CAM antigens on two glycoprotein isoforms. However, the 4.0 kb transcript was very poorly expressed as compared to the 2.5 kb species except in the colon carcinoma HT29 cell line, suggesting a differential regulation of the Lu/B-CAM messenger RNA in some tumor tissues.

Amino Acid Sequence↗
PubMed2005

Human intervertebral disc aggrecan inhibits endothelial cell adhesion and cell migration in vitro.

STUDY DESIGN: The effect of human intervertebral disc aggrecan on endothelial cell growth was examined using cell culture assays. OBJECTIVE: To determine the response of endothelial cells to human intervertebral disc aggrecan, and whether the amount and type of aggrecan present in the intervertebral disc may be implicated in disc vascularization. SUMMARY OF BACKGROUND DATA: Intervertebral disc degeneration has been associated with a loss of proteoglycan, and the ingrowth of blood vessels and nerves. Neovascularization is a common feature also of disc herniation. Intervertebral disc aggrecan is inhibitory to sensory nerve growth, but the effects of disc aggrecan on endothelial cell growth are not known. METHODS: Aggrecan monomers were isolated separately from the anulus fibrosus and nucleus pulposus of human lumbar intervertebral discs, and characterized to determine the amount and type of sulfated glycosaminoglycan side chains present. The effects of these aggrecan isolates on the cellular adhesion and migration of the human endothelial cell lines, HMEC-1 and EAhy-926, were examined in vitro. RESULTS: Homogenous substrata of disc aggrecan inhibited endothelial cell adhesion and cell spreading in a concentration dependent manner. In substrata choice assays, endothelial cells seeded onto collagen type I migrated over the collagen until they encountered substrata of disc aggrecan, where they either stopped migrating, retreated onto the collagen, or, more commonly, changed direction to align along the collagen-aggrecan border. The inhibitory effect of aggrecan on endothelial cell migration was concentration dependent, and reduced by enzymatic treatment of the aggrecan monomers with a combination of chondroitinase ABC and keratinase/keratinase II. Anulus fibrosus aggrecan was more inhibitory to endothelial cell adhesion than nucleus pulposus aggrecan. However, this difference did not relate to the extent to which the different aggrecan isolates were charged, as determined by colorimetric assay with 1,9-dimethylmethylene blue, or to marked differences in the distribution of chondroitin sulfated and keratan sulfated side chains. CONCLUSIONS: Human intervertebral disc aggrecan is inhibitory to endothelial cell migration, and this inhibitory effect appears to depend, in part, on the presence of glycosaminoglycan side chains on the aggrecan monomer.

Aggrecans↗
PubMed1996

Cadherin-mediated cell adhesion and cell motility in Drosophila trachea regulated by the transcription factor Escargot.

Coordination of cell motility and adhesion is essential for concerted movement of tissues during animal morphogenesis. The Drosophila tracheal network is formed by branching, migration and fusion of tubular ectodermal epithelia. Tracheal tip cells, located at the end of each branch that is going to fuse, extend filopodia to search for targets and later change their cell shape to a seamless ring to allow passage of lumen. The cell adhesion molecule DE-cadherin accumulates at the site of contact to form a ring that marks the site of lumen entry and is essential for the fusion. DE-cadherin expression in tip cells of a subset of branches is dependent on escargot, a zinc finger gene expressed in all tip cells. Such escargot mutant tip cells failed to adhere to each other and continued to search for alternative targets by extending long filopodia. We present evidence indicating escargot positively regulates transcription of the DE-cadherin gene, shotgun. Overexpression of DE-cadherin rescued the defect in one of the fusion points in escargot mutants, demonstrating an essential role of DE-cadherin in target recognition and identifying escargot as a key regulator of cell adhesion and motility in tracheal morphogenesis.

Animals↗
PubMed1999

Dissociated cells of the calcareous sponge clathrina: a model for investigating cell adhesion and cell motility in vitro.

The study of cell-cell and cell-substratum adhesion in vitro is useful for understanding cell behavior in a three-dimensional pattern. We have used dissociated cells (choanocytes represent the main fraction) from the calcareous sponge Clathrina, namely C. cerebrum and C. clathrus, to illustrate our present understanding on three main aspects of cell-cell and cell-substratum adhesion in vitro: (1) cytoskeletal protrusions; (2) cell behaviours on organic substrata; and (3) paths of locomotory sponge cell. Cell locomotion occurs by the extensions of scleropodial and lamellipodial protrusions, by way of actin polymerization. The extent to which cells produce these cytoplasmic processes varies according to the substratum (e.g., collagen, fibronectin, laminin, polylysine). It was found that more cell extensions were produced on collagen substrata, and this led to greater cell movement. Advancing choanocytes are not polarized. Their paths are particularly complicated, showing linear segments, which produce a more efficent cellular translocation, and winding tracts with frequent turns or loops. Small amoeboid cells describe more linear paths with a wide range of speed variation than larger cells. The presence of cell-derived substratum reduces the progressive dispersion of cells and allows cells to encounter one another in such a way that the initial random walking later turns into non-random displacement. Even though cAMP-treated cells exhibit different aggregative tactics, cAMP 10(-8) M remarkably enhances cell encounters and supports the existing information that this cyclic nucleotide represents a signal that affects cell morphology and locomotion. The bulk of data on sponge cell-cell and cell-substratum adhesion has been evaluated by mentioning the significant advances and references concerning studies of other cell systems.

Animals↗
PubMed2000

[Inhibitory effects of ligustrazine on the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1 in human umbilical vein endothelial cells induced by preeclamptic plasma].

OBJECTIVE: To determine whether plasma from preeclamptic women induces expression of intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on cultured endothelial cells, and the effects of ligustrazine (LTZ) on the expression of ICAM-1, VCAM-1. METHODS: Human umbilical vein endothelial cells (HUVEC) were isolated by collagenase mixed with trypsin. LTZ was added to HUVEC monolayers grown to confluency on 96-well microplates for 30 minutes. Then HUVEC were incubated with medium containing 20% plasma (volume/volume) either from women with preeclampsia or normotensive pregnancy or nonpregnant women. ICAM-1, VCAM-1 expression was determined after 16 hours of exposure by an enzyme-linked immunosorbent assay (ELISA) technique performed on the cell monolayer. RESULTS: There was a statistically significant increase in ICAM-1, VCAM-1 expression in the endothelial cells exposed to preeclamptic and nonpregnant plasma compared with those exposed to normotensive plasma. Pretreatment with LTZ could reduce the expression of ICAM-1 exposed to preeclamptic plasma, and reduce the expression of VCAM-1 exposed to any of the three sources of plasma. CONCLUSIONS: Preeclamptic plasma induces ICAM-1 and VCAM-1 expression in HUVEC in vitro. Ligustrazine may inhibit the upregulation effects of ICAM-1 and VCAM-1 expression induced by preeclamptic plasma.

Adult↗
PubMed2005

The spermatogenic Ig superfamily/synaptic cell adhesion molecule mast-cell adhesion molecule promotes interaction with nerves.

Nerve-mast cell interaction is involved in both homeostatic and pathologic regulations. The molecules that sustain this association have not been identified. Because synaptic cell adhesion molecule (SynCAM), alternatively named spermatogenic Ig superfamily (SgIGSF), is expressed on both nerves and mast cells and because it binds homophilically, this molecule may be a candidate. To examine this possibility, mast cells with or without SgIGSF/SynCAM were cocultured with superior cervical ganglion neurons that express SgIGSF/SynCAM, and the number of mast cells attached to neurites was counted. The attachment of mast cells with SgIGSF/SynCAM, i.e., bone marrow-derived mast cells (BMMC) from wild-type mice, was inhibited dose-dependently by blocking Ab to SgIGSF/SynCAM. Mast cells without SgIGSF/SynCAM, i.e., BMMC from microphthalmia transcription factor-deficient mice and BMMC-derived cell line IC-2 cells, were defective in attachment to neurite, and transfection with SgIGSF/SynCAM normalized this. When the nerves were specifically activated by scorpion venom, one-quarter of the attached IC-2 cells mobilized Ca(2+) after a few dozen seconds, and ectopic SgIGSF/SynCAM doubled this proportion. At points of contact between neurites and wild-type BMMC, SgIGSF/SynCAM was locally concentrated in both neurites and BMMC. SgIGSF/SynCAM on mast cells appeared to predominantly mediate attachment and promote communication with nerves.

Animals↗
PubMed2000

Beta1 integrin-mediated T cell adhesion and cell spreading are regulated by calpain.

To investigate the function of calpain in T cells, we sought to determine the role of this protease in cellular events mediated by beta1 integrins. T cell receptor cross-linked or phorbol ester-stimulated T cells binding to immobilized fibronectin induce the translocation of calpain to the cytoskeletal/membrane fraction of these cells. Such translocation of calpain is associated with proteolytic modification of protein tyrosine phosphatase 1B, increased cellular adhesion, and dramatic alterations in cellular morphology. However, affinity-related increases in T cell adhesion induced by the anti-beta1 integrin antibody 8A2 occur in a calpain-independent manner and in the absence of morphological shape changes. Furthermore, calpain undergoes activation in response to either alpha4beta1 or alpha5beta1 integrin binding to fibronectin in appropriately stimulated T cells, and calpain II as well as protein tyrosine phosphatase 1B accumulates at sites of focal contact formation. Inhibition of calpain activity not only inhibits the proteolytic modification of protein tyrosine phosphatase 1B, but also decreases the ability of T cells to adhere to and spread on immobilized fibronectin. Thus, we describe a potential regulatory role for calpain in beta1 integrin-mediated signaling events associated with T cell adhesion and cell spreading on fibronectin.

Adult↗
PubMed2002

AmpA, a modular protein containing disintegrin and ornatin domains, has multiple effects on cell adhesion and cell fate specification.

Proteins containing disintegrin domains play a variety of roles in regulating processes involving adhesion, migration and cell type specification during development of many metazoan organisms. Most disintegrin domain containing proteins belong to the ADAM (a disintegrin and a metalloprotease) family of proteins that also contain a metalloprotease domain. Here we describe a small secreted protein from Dictyostelium that contains multiple repeated domains sharing homology with both the disintegrin motif and with a second class of fibrinogen receptor antagonists, the ornatins. This protein, called AmpA for its role in modulating adhesion, differs from the ADAM family proteins in that it lacks a metalloprotease domain. Nonetheless, it appears to be involved in the same complex spectrum of developmental functions as the metazoan ADAM family proteins. Here we review the structure and evolution of this protein and its function in cell adhesion and cell type specification. We discuss possible mechanisms by which it might function and review the emerging evidence for a close coupling between cell adhesion and cell type specification.

Amino Acid Sequence↗
PubMed2000

Differential modulation of cadherin-mediated cell-cell adhesion by platelet endothelial cell adhesion molecule-1 isoforms through activation of extracellular regulated kinases.

The role of platelet endothelial cell adhesion molecule-1 (PECAM-1) in endothelial cell-cell interactions and its contribution to cadherin-mediated cell adhesion are poorly understood. Such studies have been difficult because all known endothelial cells express PECAM-1. We have used Madin-Darby canine kidney (MDCK) cells as a model system in which to evaluate the role of PECAM-1 isoforms that differ in their cytoplasmic domains in cell-cell interactions. MDCK cells lack endogenous PECAM-1 but form cell-cell junctions similar to those of endothelial cells, in which PECAM-1 is concentrated. MDCK cells were transfected with two isoforms of murine PECAM-1, Delta15 and Delta14&15, the predominant isoforms expressed in vivo. Expression of the Delta15 isoform resulted in apparent dedifferentiation of MDCK cells concomitant with the loss of adherens junctions, down-regulation of E-cadherin, alpha- and beta-catenin expression, and sustained activation of extracellular regulated kinases. The Delta15 isoform was not concentrated at cell-cell contacts. In contrast, the Delta14&15 isoform localized to sites of cell-cell contact and had no effect on MDCK cell morphology, cadherin/catenin expression, or extracellular regulated kinase activity. Thus, the presence of exon 14 in the cytoplasmic domain of PECAM-1 has dramatic effects on the ability of cells to maintain adherens junctions and an epithelial phenotype. Therefore, changes in the expression of exon 14 containing PECAM-1 isoforms, which we have observed during development, may have profound functional consequences.

Animals↗
PubMed1998

Mechanisms of epithelial cell-cell adhesion and cell compaction revealed by high-resolution tracking of E-cadherin-green fluorescent protein.

Cadherin-mediated adhesion initiates cell reorganization into tissues, but the mechanisms and dynamics of such adhesion are poorly understood. Using time-lapse imaging and photobleach recovery analyses of a fully functional E-cadherin/GFP fusion protein, we define three sequential stages in cell-cell adhesion and provide evidence for mechanisms involving E-cadherin and the actin cytoskeleton in transitions between these stages. In the first stage, membrane contacts between two cells initiate coalescence of a highly mobile, diffuse pool of cell surface E-cadherin into immobile punctate aggregates along contacting membranes. These E-cadherin aggregates are spatially coincident with membrane attachment sites for actin filaments branching off from circumferential actin cables that circumscribe each cell. In the second stage, circumferential actin cables near cell-cell contact sites separate, and the resulting two ends of the cable swing outwards to the perimeter of the contact. Concomitantly, subsets of E-cadherin puncta are also swept to the margins of the contact where they coalesce into large E-cadherin plaques. This reorganization results in the formation of a circumferential actin cable that circumscribes both cells, and is embedded into each E-cadherin plaque at the contact margin. At this stage, the two cells achieve maximum contact, a process referred to as compaction. These changes in E-cadherin and actin distributions are repeated when additional single cells adhere to large groups of cells. The third stage of adhesion occurs as additional cells are added to groups of >3 cells; circumferential actin cables linked to E-cadherin plaques on adjacent cells appear to constrict in a purse-string action, resulting in the further coalescence of individual plaques into the vertices of multicell contacts. The reorganization of E-cadherin and actin results in the condensation of cells into colonies. We propose a model to explain how, through strengthening and compaction, E-cadherin and actin cables coordinate to remodel initial cell-cell contacts to the final condensation of cells into colonies.

Actins↗
PubMed1996

Type II transglutaminase expression in rabbit articular chondrocytes in culture: relation with cell differentiation, cell growth, cell adhesion and cell apoptosis.

Depending on the cell type studied, the involvement of type II transglutaminase (TGase) has been proposed in almost any event of the cell life such as differentiation, apoptosis, growth, aging, cell morphology and adhesion, metastatic capacity or extracellular matrix stabilization. In order to define the field(s) where this enzyme may be implicated in chondrocytes, type II TGase expression was studied in chondrocytes at different passages which differentiated state was modulated by retinoic acid, dihydrocytochalasin B or staurosporin. Results showed that (i) type II TGase expression is not incompatible with type II collagen expression, a main marker of chondrocyte differentiation (ii) type II TGase expression is higher when cells are in the exponential phase of growth than when growth arrested (iii) a high type II TGase expression does not imply that cells are apoptotic although cell apoptosis correlates with increased type II TGase expression (iv) non-adherent cells do not express type II TGase whereas adherent cells do whatever their differentiation state as assessed by type II collagen synthesis. These results suggest that, in articular chondrocytes, type II TGase is specifically implicated in the cell adhesion capacity.

Alkaloids↗
PubMed2005

Protein kinase A-dependent phosphorylation of Lutheran/basal cell adhesion molecule glycoprotein regulates cell adhesion to laminin alpha5.

Lutheran (Lu) blood group and basal cell adhesion molecule (B-CAM) antigens reside on two glycoprotein (gp) isoforms Lu and Lu(v13) that belong to the Ig superfamily and differ only by the size of their cytoplasmic tail. Lu/B-CAM gps have been recognized as laminin alpha5 receptors on red blood cells and epithelial cells in multiple tissues. It has been shown that sickle red cells exhibit enhanced adhesion to laminin alpha5 when intracellular cAMP is up-regulated by physiological stimuli such as epinephrine and that this signaling pathway is protein kinase A- and Lu/B-CAM-dependent. In this study, we analyzed the relationship between the phosphorylation status of Lu/B-CAM gps and their adhesion function to laminin alpha5. We showed that Lu isoform was phosphorylated in sickle red cells as well as in erythroleukemic K562 and epithelial Madin-Darby canine kidney cells and that this phosphorylation is enhanced by different stimuli of the PKA pathway. Lu gp is phosphorylated by glycogen synthase kinase 3 beta, casein kinase II, and PKA at serines 596, 598, and 621, respectively. Alanine substitutions of serines 596 and 598 abolished phosphorylation by glycogen synthase kinase 3 beta and casein kinase II, respectively, but had no effect on adhesion of K562 cells to laminin under flow conditions. Conversely, mutation of serine 621 prevented phosphorylation by PKA and dramatically reduced cell adhesion. Furthermore, stimulation of K562 cells by epinephrine increased Lu gp phosphorylation by PKA and enhanced adhesion to laminin. It is postulated that modulation of the phosphorylation state of Lu gp might be a critical factor for the sickle red cells adhesiveness to laminin alpha5 in sickle cell disease.

Adrenergic beta-Antagonists↗
PubMed1999

Extracellular adenosine triphosphate affects neural cell adhesion molecule (NCAM)-mediated cell adhesion and neurite outgrowth.

The neural cell adhesion molecule (NCAM) plays an important role in synaptic plasticity in embryonic and adult brain. Recently, it has been demonstrated that NCAM is capable of binding and hydrolyzing extracellular ATP. The purpose of the present study was to evaluate the role of extracellular ATP in NCAM-mediated cellular adhesion and neurite outgrowth. We here show that extracellularly added adenosine triphosphate (ATP) and its structural analogues, adenosine-5'-O-(3-thiothiophosphate), beta, gamma-methylenadenosine-5'-triphosphate, beta, gamma-imidoadenosine-5-triphosphate, and UTP, in varying degrees inhibited aggregation of hippocampal neurons. Rat glial BT4Cn cells are unable to aggregate when grown on agar but acquire this capacity when transfected with NCAM. However, addition of extracellular ATP to NCAM-transfected BT4Cn cells inhibited aggregation. Furthermore, neurite outgrowth from hippocampal neurons in cultures allowing NCAM-homophilic interactions was inhibited by addition of extracellular nucleotides. These findings indicate that NCAM-mediated adhesion may be modulated by extracellular ATP. Moreover, extracellularly added ATP stimulated neurite outgrowth from hippocampal neurons under conditions non-permissive for NCAM-homophilic interactions, and neurite outgrowth stimulated by extracellular ATP could be inhibited by a synthetic peptide corresponding to the so-called cell adhesion molecule homology domain (CHD) of the fibroblast growth factor receptor (FGFR) and by FGFR antibodies binding to this domain. Antibodies against the fibronectin type-III homology modules of NCAM, in which a putative site for ATP binding and hydrolysis is located, also abolished the neurite outgrowth-promoting effect of ATP. The non-hydrolyzable analogues of ATP all strongly inhibited neurite outgrowth. Our results indicate that extracellular ATP may be involved in synaptic plasticity through a modulation of NCAM-mediated adhesion and neurite outgrowth.

Adenosine Diphosphate↗
PubMed1993

Angiopeptin, the octapeptide analogue of somatostatin, decreases rat heart endothelial cell adhesiveness for mononuclear cells.

The effect of angiopeptin, a stable analogue of somatostatin, was studied on basal and interleukin-1-beta-induced endothelial cell adhesiveness for mononuclear cells, and compared to the effect of somatostatin. Angiopeptin and somatostatin decreased basal and interleukin-1-beta-induced endothelial cell adhesiveness for mononuclear cells. The decreased mononuclear cells adhesion to endothelial cells exposed to angiopeptin and somatostatin is not due to modulation of the expression of intrecellular adhesion molecule-1 because neither angiopeptin nor somatostatin decreased basal and interleukin-1-beta-induced expression of this adhesion molecule. The effect of angiopeptin in inhibiting endothelial cell adhesiveness for mononuclear cells was abolished by addition of dibutyryl-cyclic AMP. Angiopeptin induced a transient decrease in basal and interleukin-1-beta-induced cyclic AMP levels in endothelial cells. Exposure of unstimulated and interleukin-1-beta-activated endothelial cells to KT5720, a specific inhibitor of cyclic AMP-dependent protein kinase, decreased endothelial cell adhesiveness for mononuclear cells. Thus, angiopeptin most likely diminishes endothelial adhesiveness for mononuclear cells by affecting the cyclic AMP-dependent protein kinase signal transduction pathway. The findings suggest that angiopeptin and somatostatin may modify the development of the immune response by attenuating endothelial cell adhesiveness for mononuclear cells. Angiopeptin may have a potential clinical application as a modulator of some aspects of the immune response due to its long half-life and prolonged inhibitory effect on interleukin-1-beta induced endothelial adhesiveness for mononuclear cells.

Amino Acid Sequence↗
PubMed1998

Differential expression and distribution of focal adhesion and cell adhesion molecules in rat hepatocyte differentiation.

Hepatocytes in primary culture enter into clonal proliferation in the chemically defined hepatocyte growth medium in the presence of hepatocyte growth factor and epidermal growth factor. Hepatocyte proliferation is associated with loss of differentiated gene expression. Overlay of matrix derived from Engelbreth-Holm-Swarm mouse sarcoma (Matrigel) on proliferating hepatocytes induces reexpression of the hepatic differentiation marker genes. To explore the role of matrix in the differentiation process of hepatocytes, we examined the mRNAs of fibronectin, vitronectin, and entactin in proliferating hepatocytes and Matrigel-treated hepatocytes. Fibronectin mRNA increased in proliferating hepatocytes at days 2-10 and then decreased; however, vitronectin mRNA disappeared in proliferating hepatocytes and was reexpressed in Matrigel-treated hepatocytes. We also found that focal adhesion kinase and paxillin were strongly increased in Matrigel-treated hepatocytes, and E-cadherin and beta-catenin slightly increased in Matrigel-treated hepatocytes, suggesting that both cell-to-extracellular matrix and cell-to-cell interactions may be an essential part of hepatocyte differentiation. To evaluate the distribution of focal adhesion associated molecules and cell-to-cell adhesion molecules, Triton X-100 soluble and insoluble fractions were examined at days 8, 9, 10, and 11 in proliferating hepatocytes and Matrigel-treated cells. We found that E-cadherin in Triton X-100 insoluble fractions dramatically decreased in Matrigel-treated hepatocytes; however, beta-catenin strongly increased in Triton X-100 soluble fractions of Matrigel-treated hepatocytes. These results suggest that the distribution of both focal adhesion associated molecules and cell adhesion molecules are reorganized during the process of differentiation induced by overlay of Matrigel.

Animals↗
PubMed1993

Changes in cell adhesion and cell proliferation are associated with expression of tissue non-specific alkaline phosphatase.

Tissue non-specific alkaline phosphatase is a membrane-bound glycoprotein enzyme which is characterized by its phosphohydrolytic, protein phosphatase, and phosphotransferase activities. This enzyme is distributed virtually in all mammalian tissues, particularly during embryonic development. Its expression is stage-specific and can be demonstrated in the developing embryo as early as the 2-cell stage. It has been suggested that tissue non-specific alkaline phosphatase might play a role in tissue formation. In the study reported here, a gene-transfer approach was employed to investigate possible roles for this enzyme by inserting the cDNA for rat tissue non-specific alkaline phosphatase into CHO and LLC-PK1 cells. Permanently transfected cell-lines expressing varying levels of alkaline phosphatase were established. The data showed that functional enzyme was expressed in the transfected cells. Cell spreading and attachment were enhanced in transfected CHO cells expressing high levels of tissue non-specific alkaline phosphatase but not in the LLC-PK1 cells. Further, in CHO cells, proliferation was shown to be inversely proportional to the level of the tissue non-specific alkaline phosphatase expression. Homotypic cell association was demonstrated in both alkaline phosphatase-positive and alkaline phosphatase-negative cells in both CHO and LLC-PK1 cell-lines. Taken together, these findings suggest that in addition to a role in mineralization of bone, tissue non-specific alkaline phosphatase might also play a role in other cell activities, including those related to differentiation, such as cell-cell or cell-substrate interaction and proliferation.

Alkaline Phosphatase↗