SEARCH · PubMed Health

Results for “Integrin alpha3”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2002

Induction of alpha-catenin, integrin alpha3, integrin beta6, and PDGF-B by 2,8-dihydroxyadenine crystals in cultured kidney epithelial cells.

BACKGROUND: Homozygous adenine phosphoribosyltransferase (APRT) deficiency is associated with 2,8-dihydroxyadenine (DHA) nephrolithiasis. Using whole kidney RNA from Aprt knockout mice, we previously showed that the renal deposition of DHA leads to changes in the expression of genes involved in tissue injury. To determine the cellular basis for these changes, we investigated gene expression in cultured human kidney (NHK-C) and African green monkey (BSC-1) epithelial cells exposed to DHA or calcium oxalate monohydrate (COM) crystals. METHODS: First-strand cDNAs, synthesized from mRNA isolated from treated and untreated cells, were hybridized to membrane-bound cDNA arrays containing 588 genes associated with various physiological and pathological processes. Changes in gene expression were confirmed by reverse transcription PCR. RESULTS: Twenty-seven percent of the array cDNAs were expressed in untreated NHK-C cells at varying levels relative to a housekeeping gene. The expression of three adhesion molecules (alpha-catenin, integrin alpha3, and integrin beta6) and platelet-derived growth factor B (PDGF-B) was elevated following exposure of NHK-C cells to DHA. Increased expression of the adhesion molecules was also observed in BSC-1 cells, but PDGF-B expression could not be detected. COM crystals also stimulated the expression of these four genes in NHK-C cells, but the expression profile was quantitatively different compared with DHA. CONCLUSIONS: These findings suggest that DHA crystals stimulate the expression of specific genes in kidney epithelial cells and that the pathways for DHA-induced cell injury may be similar to those for COM crystals. The induction of adhesion molecules and PDGF-B may affect cell-cell or cell-matrix interactions and/or alter the actin cytoskeleton. These alterations may ultimately contribute to crystal-induced renal injury.

Adenine↗

PubMed1999

CD9 is expressed in extravillous trophoblasts in association with integrin alpha3 and integrin alpha5.

The CD9 molecule is a 24-27 kDa cell surface glycoprotein, which may be related to Schwann cell migration and adhesion. In this study, we examined the expression of CD9 in human extravillous trophoblasts, which invade into the endometrium during implantation and placentation. CD9 was detected immunohistochemically on the extravillous trophoblasts in the cell columns of first trimester placentae, but not on villous trophoblasts. In the second and third trimester, CD9 was highly expressed on the extravillous trophoblasts in the basal plate of placentae, and in the chorion laeve in the fetal membrane of term placentae. The molecular mass of CD9 in the chorion laeve was shown to be 27 kDa by Western blotting. The mRNA of CD9 was also detected in the chorion laeve by reverse transcription-polymerase chain reaction (RT-PCR). Proteins were purified from chorion laeve by affinity chromatography with anti-integrin alpha3 and alpha5 monoclonal antibodies and Western blotting, revealed that CD9 was associated with both integrins. These findings indicate that CD9 is a differentiation-related molecule present in the extravillous trophoblasts. Since it is associated with integrin alpha5 which has been proposed to regulate trophoblast invasion, CD9 may be implicated in trophoblast invasion at the feto-maternal interface.

Antigens, CD↗

PubMed1999

Characterization of mouse integrin alpha3 subunit gene.

Integrin alpha3beta1 (VLA-3) is an adhesion receptor for extracellular matrix proteins including various isoforms of laminin. We have isolated mouse genomic clones encoding the integrin alpha3 subunit and deduced the exon/intron organization. The mouse integrin alpha3 subunit gene is encoded by 26 exons spanning 40 kb. The exon/intron structure of the integrin alpha3 subunit gene resembles that of the integrin alpha6 subunit gene, but differs somewhat from those of other members of the integrin family. We have demonstrated that the cytoplasmic domain splicing variants of the alpha3 subunits (alpha3A and alpha3B) are generated by alternative exon usage. We also cloned the 5'-flanking region and performed a preliminary analysis of its promoter activity in various tumor cell lines with different degrees of integrin alpha3 expression. Following transfection, activity in the luciferase assay was found to be roughly correlated with the expression level of integrin alpha3 as measured by flow cytometry. Furthermore, the luciferase assay was performed with normal and SV-40- or polyoma virus-transformed fibroblasts. In mouse, human, and hamster fibroblasts, higher levels of luciferase expression were observed in transformed cells than in normal cells. This result is consistent with our previous finding that integrin alpha3 expression at both the protein and mRNA levels is enhanced upon oncogenic transformation of fibroblasts by tumor viruses.

Alternative Splicing↗

PubMed2001

Loss of motility-related protein 1 (MRP1/CD9) and integrin alpha3 expression in endometrial cancers.

BACKGROUND: MRP1/CD9 and integrin alpha3 have played crucial roles in cell adhesion, motility, and signaling events. The loss of MRP1/CD9 and integrin alpha3 has been involved in tumor growth and metastasis of cancer cells. The aim of the current study was to clarify the clinical significance of MRP1/CD9 and integrin alpha3 in endometrial cancer. METHODS: The expression of MRP1/CD9 and integrin alpha3 from the same tissue sample were examined immunohistochemically in 15 patients with normal endometrium and in 56 patients with uterine endometrioid adenocarcinoma. Disease-free survival curves were estimated using the Kaplan-Meier method and analyzed by the log-rank test between the positive and reduced expression statuses of both MRP1/CD9 and integrin alpha3. These expressions and clinicopathologic variables were analyzed univariately and multivariately. RESULTS: In normal endometrium, MRP/CD9 was expressed at the cell membrane of cell contact sites, and the expression of integrin alpha3 was detected also at the cell membrane of cell contact sites and at borders of stromal tissues. In patients with endometrioid adenocarcinoma, 17 cases showed reduced expression of MRP1/CD9, and 20 cases had reduced expression of integrin alpha3. Fourteen cases indicated a reduced expression of both MRP1/CD9 and integrin alpha3. Each reduced expression of MRP1/CD9 or integrin alpha3 was significantly correlated with histologic grade and metastasis. Multivariate analysis using the Cox regression model disclosed that age at surgery, metastasis, and expression status of MRP1/CD9 were significant prognostic factors for disease-free survival. CONCLUSIONS: These findings suggested that the analysis for the expression statuses of MRP1/CD9 and integrin alpha3 may provide important information on the clinical behavior of endometrial cancer.

Antigens, CD↗

PubMed2003

Integrin-alpha3 mediates binding of Chordin to the cell surface and promotes its endocytosis.

Dorsoventral patterning in animal development is regulated by a morphogenetic gradient of Bone morphogenetic protein signalling, which is established by a set of proteins that are conserved from Drosophila to vertebrates. These include Chordin (Chd)/Short gastrulation, Xolloid/Tolloid and Twisted gastrulation. Here, we report the identification of a cell-surface component of this morphogenetic pathway. Prompted by the observation that Chd protein bound to the surface of certain cell lines with subnanomolar affinity, we identified two cell-surface proteins that bind to Chd, one of which corresponds to Integrin-alpha3. Integrin-alpha3 and Chd are co-expressed in the Xenopus embryo. Transfection of Integrin-alpha3 increased the binding of Chd to the cell surface, which was competed by an excess of soluble Integrin-alpha3. After binding to the cell surface, Chd was translocated into intracellular endocytic compartments in a temperature-dependent manner. We propose that Integrin-alpha3 may regulate the concentration of Chd protein in the extracellular space by endocytosis.

Animals↗

PubMed2002

[Detection of the expression of alpha3-integrin on hantavirus permissive cells].

BACKGROUND: To express and purify human alpha3-integrin to serve as the antigen to prepare its antibody and to separate the Vero cell clones without expression of alpha3-integrin. METHODS: The human alpha3-integrin gene was amplified by using RT-PCR, then subcloned into a pQE30 expression vector and expressed in E. coli. The gene expression was confirmed by Western blot assay. Rabbit was inoculated with purified antigen to stimulate the antibody generation. The target Vero cells were separated by negative selection using antibody plus complement mediated cytolysis. The separated cell clones were confirmed by immunofluorescence and Western blot assay. RESULTS: The alpha3- integrin gene was cloned and expressed effetively, Western blot assay revealed that the expressed protein held good immune reactivity. High titer antibody was generated. However the expression of alpha3-integrin was not detected on Vero, VeroE6, Hep-2, 2BS and 293 cells. CONCLUSIONS: The results of the study suggested that hantavirus has other receptors on Vero cells beside alpha 3-integrin.

Animals↗

PubMed1998

Reduced integrin alpha3 expression as a factor of poor prognosis of patients with adenocarcinoma of the lung.

PURPOSE: We investigated the possible association between integrin alpha3 and motility-related protein (MRP-1), cluster of differentiation antigen 9 (CD9) gene expression in non-small-cell lung cancer (NSCLC) and evaluated the prognostic significance of integrin alpha3 expression. PATIENTS AND METHODS: We performed a retrospective study of integrin alpha3 and MRP-1/CD9 expression in resected tumor tissues from 151 NSCLC patients using quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. RESULTS: The ratio of integrin alpha3/beta-actin expression ranged from 0 to 5.87 (mean was 0.80; median, 0.70). Using the cutoff value of 0.7, there were 78 (52%) integrin alpha3-positive tumors and 73 (48%) tumors with reduced integrin alpha3 expression. The immunohistochemical results agreed well with those of the RT-PCR assays, and 88% had no discrepancy. In case of discrepancy, the results of RT-PCR were used in specimen classification. Integrin alpha3 gene expression was independent from MRP-1/CD9 gene expression. No significant association was found between integrin alpha3 expression and the patients' clinical characteristics. The overall survival rate of patients with integrin alpha3-positive NSCLCs was only slightly better than that of individuals whose tumors had reduced integrin alpha3 expression (55.9% v 47.1%; P = .085). By comparison, the overall survival rate of patients with integrin alpha3-positive adenocarcinomas was strikingly greater than in those whose tumors had reduced gene expression (54.4% v 35.2%; P = .004). Multivariate analysis with the Cox regression model of NSCLC and adenocarcinoma indicated that integrin alpha3 expression correlated better (P = .0188 and P = .0008, respectively) with the overall survival rate than other variables, except lymph node status. CONCLUSION: No significant association was found between integrin alpha3 and MRP-1/CD9 gene expression in lung cancer. However, reduced integrin alpha3 expression is a poor prognosis factor in patients with adenocarcinomas.

Adenocarcinoma↗

PubMed2005

RNA-dependent integrin alpha3 protein localization regulated by the Muscleblind-like protein MLP1.

We show that localized expression of the integrin alpha3 protein is regulated at the level of RNA localization by the human homologue of Drosophila Muscleblind, MLP1/MBLL/MBNL2, a unique Cys3His zinc-finger protein. This is supported by the following observations: MLP1 knockdown abolishes localization of integrin alpha3 to the adhesion complexes; MLP1 is localized in adhesion plaques that contain phospho-focal adhesion kinase; this localization is microtubule-dependent; integrin alpha3 transcripts colocalize with MLP1 in distinct cytoplasmic loci; integrin alpha3 transcripts are physically associated with MLP1 in cells and MLP1 binds to a specific ACACCC motif in the integrin alpha3 3' untranslated region (UTR) in vitro; and a green fluorescent protein (GFP) open reading frame-integrin alpha3 3' UTR chimeric gene directs GFP protein localization to distinct cytoplasmic loci near the cell periphery, which is dependent on MLP1 and is mediated by the ACACCC motif but is independent of the integrin alpha3 signal peptide.

Amino Acid Sequence↗

PubMed2004

Podocyte migration during nephrotic syndrome requires a coordinated interplay between cathepsin L and alpha3 integrin.

Podocyte foot process effacement and disruption of the slit diaphragm are typically associated with glomerular proteinuria and can be induced in rats by the injection of puromycin aminonucleoside. Here, we show that the induction of puromycin aminonucleoside nephrosis involves podocyte migration conducted by a coordinated interplay between the cysteine protease cathepsin L and alpha(3) integrin. Puromycin aminonucleoside treatment up-regulates cathepsin L expression in podocytes in vivo as well as expression and enzymatic activity of cathepsin L in podocytes in vitro. Isolated podocytes from mice lacking cathepsin L are protected from cell puromycin aminonucleoside-induced cell detachment. The functional significance of cathepsin L expression was underscored by the observation that puromycin aminonucleoside-induced cell migration was slowed down in cathepsin L-deficient podocytes and by the preservation of cell-cell contacts and expression of vital slit diaphragm protein CD2AP. Cathepsin L expression and activity were induced in podocytes lacking alpha(3) integrin. Similarly, acute functional inhibition of alpha(3) integrin in wild type podocytes with a blocking antibody increased the expression of cathepsin L activity. Down-regulation of alpha(3) integrin protected against puromycin aminonucleoside-induced podocyte detachment. In summary, these data establish that podocyte foot process effacement is a migratory event involving a novel interplay between cathepsin L and alpha(3) integrin.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Integrin alpha3 expression as a prognostic factor in colon cancer: association with MRP-1/CD9 and KAI1/CD82.

Recently, we established that a murine monoclonal antibody (MAb) MH8-4 inhibits the motility of the colon cancer cell line RPMI4788 and that it recognizes integrin alpha3. In addition, we have also cloned the motility-related protein-1 (MRP-1)/cluster of differentiation 9 (CD9) as a metastasis suppressor molecule. We investigated integrin alpha3 expression in 114 resected colon cancers using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) to evaluate whether these experimental results are of relevance in the prognosis of actual colon cancers. Furthermore, we investigated the correlation of integrin alpha3 with MRP-1/CD9 and KAI1/CD82. Sixty patients (52.6%) were evaluated as integrin alpha3-positive and 54 patients (47.4%) as integrin alpha3-negative. Integrin alpha3 expression was associated with tumor status, lymph node status and pathologic stage. The overall and disease-free survival rates for patients whose tumors were positive for integrin alpha3 were significantly higher than for those with integrin alpha3-negative tumors (p < 0.001 and p < 0.001, respectively). This same tendency was observed in node-negative patients (p = 0.007 and p = 0.001, respectively). Integrin alpha3 was found to be the significant prognostic factor in a multivariate analysis using the Cox proportional hazards model (p = 0.036). A correlation was found between integrin alpha3 with MRP-1/CD9 and KAI1/CD82 for stage I tumors. However, no correlation was found in stage III tumors. Our data seem to suggest that low expression of integrin alpha3 is a useful indicator of a poor prognosis for colon cancer patients and that colon cancer progresses following collapse of the complex formed by integrin alpha3 with MRP-1/CD9 and KAI1/CD82.

Adenocarcinoma↗

PubMed2001

Calreticulin is directly involved in anti-alpha3 integrin antibody-mediated secretion and activation of matrix metalloprotease-2.

Matrix metalloprotease-2 (MMP-2) plays a pivotal role in cancer invasion and metastasis. Invasive human rhabdomyosarcoma cells (RD) secrete proMMP-2. We recently reported that anti-alpha3 integrin antibody induced the activated form of MMP-2 and enhanced proMMP-2 secretion by RD cells with concomitant enhancement of RD cell invasion. Since recent studies showed that calreticulin interacts with integrin alpha subunit, we hypothesized that calreticulin may be involved in signal transduction of anti-alpha3 integrin antibody-mediated MMP-2 secretion and activation. Here we demonstrate that anti-alpha3 integrin antibody induced a transient enhanced interaction of calreticulin with alpha3 integrin. Transfection of antisense oligonucleotides of calreticulin in RD cells abrogated the interaction between calreticulin and alpha3 integrin, and completely suppressed activation of MMP-2 and enhanced secretion of proMMP-2 induced by anti-alpha3 integrin antibody. Transient overexpression of calreticulin cDNA in RD cells significantly increased secretion of proMMP-2. The results demonstrate for the first time that calreticulin is directly involved in MMP-2 secretion and activation.

Antibodies↗

PubMed2006

Integrin alpha3 subunit participates in myoblast adhesion and fusion in vitro.

Satellite cells are myogenic precursor cells, participating in growth, and regeneration of skeletal muscles. The proteins that play a role in myogenesis are integrins. In this report, we show that the integrin alpha3 subunit is expressed in quiescent satellite cells and activated myoblasts. We also find that in myoblasts the integrin alpha3 subunit is localized at cell-cell and cell-extracellular matrix contacts. We notice that increase in protein and mRNA encoding the integrin alpha3 subunit accompanies myoblast differentiation. Using double immunofluorescence and immunoprecipitation experiments, we demonstrate that the integrin alpha3 subunit co-localizes with actin, and binds the integrin beta1 subunit and ADAM12, suggesting that the complex alpha3beta1/ADAM12 is probably involved in myoblast fusion. Importantly, overexpression of the full-length integrin alpha3 subunit increases myoblast fusion whereas an antibody against its extracellular domain inhibits fusion. These data demonstrate that the integrin alpha3 subunit may contribute to satellite cell activation and then myoblast adhesion and fusion.

ADAM Proteins↗

PubMed2004

Immuno-histochemical expression of alpha1, alpha2 and alpha3 integrin subunits during angiogenesis in vitro.

Aortic explants were obtained from mouse fetuses and cultured in collagen gels. Immuno-fluorescence microscopy, antibodies (anti alpha1, alpha2 and alpha3 integrin subunits) were used. Fibroblastic cells migrated from the aortic explant after one day of cultivation. The migrating cells located in the peripheral part of the aortic explant were positive for alpha1 and alpha2 integrin subunit antibodies. Immuno-fluorescence-positive staining for the alpha3 integrin subunit antibody was clearly seen in the migrating cells located near the aortic explant and surrounding tube-like structures. In an immuno-electron microscope study performed by pre-embedding immuno labeling, gold particles associated with the alpha3 integrin subunit were found to reside on the membranes of the cells surrounding the capillary-like tubes. Two synthetic peptides, GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro) and KDGEA (Lys-Asp-Gly-Glu-Ala), were added to the growth medium to study their effects on cell migration. KDGEA, a compound containing the recognition sequence for alpha2beta1 integrin, decreased cell migration, while GRGDSP exhibited no effect. The migration of fibroblastic cells is an important phenomenon for tube formation. The present study suggested that the alpha1 and alpha2 integrin subunits are both involved in the cell migration, and more specifically, that the alpha2 integrin subunit participates in cell migration through the KDGEA sequence. The alpha3 integrin subunit played a role in tube formation.

Animals↗

PubMed2003

The alpha2 and alpha3 integrins are required for morphologic differentiation of an intestinal epithelial cell line.

BACKGROUND: The molecular mechanisms controlling intestinal epithelial cell differentiation are poorly defined because of the difficulty of growing normal intestinal cells. We have taken advantage of the ability of the Caco-2 cell line to acquire a glandular phenotype in 3-dimensional (3-D) culture systems to investigate the role of alpha2 and alpha3 integrins in morphologic differentiation. METHODS: Caco-2 cells transfected with sense or antisense DNA constructs of alpha2 or alpha3 integrins were grown in 3-D Matrigel or collagen I in the presence or absence of integrin function-blocking antibodies. We used light and confocal microscopy, BrDU incorporation, TUNEL assay, a fluorometric adhesion assay, FACS analysis, and Western blot analysis to study the effect of extracellular matrix (ECM) and integrins on morphology, polarization, proliferation, apoptosis, cell adhesion, and integrin expression. RESULTS: Compared to collagen I, Caco-2 cells cultured in 3-D Matrigel display cytoskeletal and adherens junction rearrangements and decreased proliferation consistent with cellular differentiation. These changes, which are inhibited by alpha2 and alpha3 blocking monoclonal antibodies and alpha2 and alpha3 antisense DNA transfection, were associated with an increase in alpha3 integrin expression. CONCLUSIONS: We demonstrated that signaling through both constitutively expressed alpha2 integrin and Matrigel-induced alpha3 integrin expression is required to acquire a differentiated phenotype in Caco-2 cells.

Antibodies, Monoclonal↗

PubMed1999

Monoclonal antibody ONS-M21 recognizes integrin alpha3 in gliomas and medulloblastomas.

The monoclonal antibody ONS-M21 recognizes an antigen found on the surface of glioma and medulloblastoma cells but does not react with the antigens of normal brain tissue. We purified and identified the 140-kDa protein by means of an antibody-binding affinity column. This 140-kDa antigen has sequences homologous to the amino-terminal region and five parts of the internal domain of integrin alpha3. When the integrin alpha3-related sequences was amplified and used to analyse the mRNA of glioma and medulloblastoma surgical specimens, the transcription level of integrin alpha3 mRNA appeared to be quantitatively correlated with the grade of malignancy. These findings suggest that the ONS-M21 antibody, which reacts with integrin alpha3, might be useful in the diagnosis of gliomas and medulloblastomas.

Amino Acid Sequence↗

PubMed2006

Transforming growth factor-beta1 upregulates transcription of alpha3 integrin gene in hepatocellular carcinoma cells via Ets-transcription factor-binding motif in the promoter region.

The invasive and metastatic potentials of hepatocellular carcinoma (HCC) are positively correlated with the expression level of alpha3beta1 integrin, a high-affinity adhesion receptor for laminin isoforms. Transforming growth factor (TGF)-beta1 stimulates non-invasive HCC cells to acquire invasive phenotypes in association with the enhanced expression of alpha3 integrin. In this study, we investigated the molecular mechanism underlying the upregulation of alpha3beta1 integrin by TGF-beta1 in non-invasive HepG2 HCC cells. The treatment of HepG2 cells with TGF-beta1 induced the expression of alpha3 integrin and potentiated these cells to adhere to laminin-5 and to migrate through laminin-5-coated membranes. The promoter activity was measured by luciferase assay with a series of deletion constructs of the 5'-flanking region of the mouse alpha3 integrin gene, and the results showed that the -260/-119 region (relative to the major transcription start site) contained elements responsive to TGF-beta1 stimulation. The introduction of mutations into the putative consensus binding sequence for the Ets-family of transcription factors located at -133 greatly decreased the promoter activity responding to TGF-beta1 stimulation. The nuclear proteins extracted from TGF-beta1-stimulated HepG2 cells yielded a larger amount of DNA-nuclear protein complexes than did those extracted from unstimulated cells, as determined by an electrophoretic mobility shift assay using an oligonucleotide containing the Ets-site as a probe. These results suggest that TGF-beta1 stimulates HepG2 cells to express a higher level of alpha3 integrin by transcriptional upregulation via Ets transcription factors and to exhibit a more invasive phenotype.

Base Sequence↗

PubMed2006

Characterization of the promoter for the alpha3 integrin gene in various tumor cell lines: roles of the Ets- and Sp-family of transcription factors.

The alpha3beta1 integrin is an adhesion receptor for extracellular matrix proteins, including laminin isoforms, and plays crucial roles in the organization of epithelial and endothelial tissues. The aberrant expression of this adhesion molecule on tumor cells is associated with their invasive and metastatic potentials. In the present study, we analyzed the elements essential for alpha3 integrin gene expression in various tumor cell lines with different tissue origins by luciferase assay. An approximately 0.3 kb fragment of the 5'-flanking region of the mouse alpha3 integrin gene (-260/+84, relative to the major transcription start site) showed strong promoter activity in all six examined tumor cell lines. However, we found that these cell lines could be divided into two groups according to the level of dependency on the putative Ets-transcription factor binding motif located at -133. This motif was previously shown to be crucial for alpha3 integrin expression in MKN1 gastric carcinoma cells. The gene expression in one group of cell lines was upregulated mainly by the Ets motif, whereas that in the other group was less dependent on the Ets motif. We then postulated that additional regulatory elements were responsible for the expression of alpha3 integrin, and found that a GC-rich motif at -69 was another important element. An electrophoretic mobility shift assay using specific antibodies and a Western blot analysis of nuclear proteins revealed that the Sp3-transcription factor bound to this GC-rich motif. These results suggest that the Sp3 and Ets transcription factors cooperatively regulate alpha3 integrin gene expression and that the contribution of each element depends on the type of tumor cells.

Animals↗

PubMed1998

Isolation and characterization of laminin-10/11 secreted by human lung carcinoma cells. laminin-10/11 mediates cell adhesion through integrin alpha3 beta1.

A panel of human tumor cell lines was screened for selective expression of laminin alpha5 chain, a newly identified laminin subunit comprising laminin-10 (alpha5 beta1 gamma1) and -11 (alpha5 beta2 gamma1). The lung adenocarcinoma cell line A549 was found to express the alpha5 chain at relatively high levels but no detectable amounts of other alpha chains. The laminin variants containing alpha5 chain were purified from the conditioned medium of A549 cells by immunoaffinity chromatography using the anti-laminin monoclonal antibody 4C7 which was shown recently to recognize the laminin alpha5 chain (Tiger, C.-F., Champliaud, M.-F., Pedrosa-Domellof, F., Thornell, L.-E., Ekblom, P., and Gullberg, D. (1997) J. Biol. Chem. 272, 28590-28595). The purified laminin variants consisted of three chains with molecular masses of 350, 220, and 210 kDa. The 350-kDa chain was specifically recognized by another anti-alpha5 chain monoclonal antibody capable of recognizing denatured alpha5 chain on immunoblots, whereas the 210-kDa chain was recognized by an anti-gamma1 chain antibody. The purified alpha5 chain-containing laminin variants (hereafter referred to as laminin-10/11) were highly active in mediating adhesion of A549 cells to the substratum with potency as high as that of laminin-5 and significantly higher than those of laminin-1, laminin-2/4, or fibronectin. Adhesion to substrata coated with laminin-10/11 was specifically inhibited by anti-integrin antibodies directed against the integrin alpha3 or beta1 subunit but not by those against alpha2 or alpha6 subunit, indicating that laminin-10/11 is specifically recognized by integrin alpha3 beta1. Given the wide distribution of laminin-10/11 in the basement membrane of various tissue types and dominant expression of integrin alpha3 beta1 in most epithelial cells, specific interaction of laminin-10/11 with integrin alpha3 beta1 may play an important role in in vivo regulation of proliferation and differentiation of epithelial cells through the basement membrane.

Cell Adhesion↗