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Pulido D, Hussain SA, Hohenester E. Crystal Structure of the Heterotrimeric Integrin-Binding Region of Laminin-111. Structure 2017; 25:530-535. [PMID: 28132784 PMCID: PMC5343747 DOI: 10.1016/j.str.2017.01.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 12/16/2016] [Accepted: 01/05/2017] [Indexed: 01/05/2023]
Abstract
Laminins are cell-adhesive glycoproteins that are essential for basement membrane assembly and function. Integrins are important laminin receptors, but their binding site on the heterotrimeric laminins is poorly defined structurally. We report the crystal structure at 2.13 Å resolution of a minimal integrin-binding fragment of mouse laminin-111, consisting of ∼50 residues of α1β1γ1 coiled coil and the first three laminin G-like (LG) domains of the α1 chain. The LG domains adopt a triangular arrangement, with the C terminus of the coiled coil situated between LG1 and LG2. The critical integrin-binding glutamic acid residue in the γ1 chain tail is surface exposed and predicted to bind to the metal ion-dependent adhesion site in the integrin β1 subunit. Additional contacts to the integrin are likely to be made by the LG1 and LG2 surfaces adjacent to the γ1 chain tail, which are notably conserved and free of obstructing glycans.
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Affiliation(s)
- David Pulido
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, London SW7 2AZ, UK
| | - Sadaf-Ahmahni Hussain
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, London SW7 2AZ, UK
| | - Erhard Hohenester
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, London SW7 2AZ, UK.
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2
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Abstract
BACKGROUND Iatrogenic tumor implantation within surgical sites can compromise curative cancer surgery. Cancer cell adhesion to extracellular matrix proteins is mediated by diverse matrix receptors, most notably integrins. Divalent cations may modulate integrin-ligand interactions in some cells. MATERIALS AND METHODS We studied adhesion of SW620 and Caco-2 human colon cancer cells to collagen I, the dominant collagen of the interstitial matrix, and confirmed our results in primary human colon cancer cells from surgical specimens. Single cell suspensions in either HEPES/NaCl buffer or media supplemented with 0-1 mM Mn2+ or Mg2+, and 0-10 mM Zn2+ or Ca2+ were plated onto collagen-I-precoated dishes for 30 min. RESULTS Supplementation of the HEPES/NaCl/BSA buffer with 1 mM Mn2+, Mg2+, Zn2+, or Ca2+ affected adhesion differently. Mn2+ (1 mM) markedly promoted SW620 adhesion vs control (21.17 +/- 0.08-fold). Mg2+ (1 mM) had a similar but lesser effect (14.71 +/- 0.02-fold). However, 1-10 mM Ca2+ inhibited basal cell adhesion by 22.0 +/- 3.1 to 88.0 +/- 7.3 % inhibition. Ca2+ (2.5-10 mM) also inhibited Mn2+-induced adhesion. Zn2+ stimulated basal adhesion slightly at lower concentrations but inhibited Mn2+-stimulated adhesion similarly to Ca2+ at higher concentrations. Results were duplicated in conventional serum containing culture medium supplemented with these cations. Caco-2 cells and primary cancer cells yielded similar results. All results are significant to P < 0.01. DISCUSSION Integrin-mediated colon cancer cell adhesion is affected by extracellular divalent cation concentrations. Washing the surgical site with dilute calcium or zinc solutions might diminish perioperative tumor implantation.
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Affiliation(s)
- Vijayalakshmi Thamilselvan
- Department of Surgery, Wayne State University and John D. Dingell VA Medical Center, Detroit, Michigan 48201-1932, USA
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3
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Andresen JL, Ledet T, Hager H, Josephsen K, Ehlers N. The influence of corneal stromal matrix proteins on the migration of human corneal fibroblasts. Exp Eye Res 2000; 71:33-43. [PMID: 10880274 DOI: 10.1006/exer.2000.0850] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Motivated by the alterations seen in the corneal matrix composition after photorefractive keratectomy and the migration of corneal keratocytes seen following this procedure, the locomotor response of corneal stromal fibroblasts to various extracellular matrix proteins was determined. In addition, the involvement of integrin mediated attachment to the matrix proteins was investigated. Quantitative invasion assays were performed using collagen gels, supplemented with either fibronectin, tenascin, collagen type V, collagen type VI, chondroitin sulfate or keratan sulfate. The ultrastructure of the gels was visualized by scanning electron microscopy and related to the migration results. The extent of alpha(1)beta(1), alpha(2)beta(1), alpha(3)beta(1)and alpha(5)beta(1)integrin mediated attachment to the matrix proteins was evaluated using blocking antibodies. Fibronectin increased corneal fibroblast migration significantly, and served as an excellent substrate for cellular attachment, mediated by the alpha(5)beta(1)integrin. Addition of tenascin to the fibronectin-containing gels disrupted these effects, while attachment to this matrix also involved the integrins alpha(2)beta(1)and alpha(3)beta(1). Chondroitin sulfate and collagen types V and VI primarily altered the structure of the collagen matrix, resulting in an inhibition of migration by the collagens and an increase by chondroitin sulfate. They all served as poor substrates for attachment. Thus, the migratory activity of corneal fibroblasts in vitro is influenced by the composition of the surrounding extracellular matrix, either by integrin mediated cell-matrix interactions or through matrix-matrix interactions. This study provides evidence that the provisional matrix deposited in a corneal stromal wound may facilitate the entry of migrating corneal fibroblasts.
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Affiliation(s)
- J L Andresen
- Department of Ophthalmology, Aarhus University Hospital, Denmark.
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4
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Lin L, Daneshvar C, Kurpakus-Wheater M. Evidence for differential signaling in human conjunctival epithelial cells adherent to laminin isoforms. Exp Eye Res 2000; 70:537-46. [PMID: 10866002 DOI: 10.1006/exer.1999.0811] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Both the laminin composition of the basement membrane and the keratin intermediate filament composition of the epithelial cell differs between cornea and conjunctiva, suggesting that at least some aspects of ocular surface epithelial cell differentiation may be regulated by extracellular matrix. The purpose of this study was to analyse the role of beta1 integrin in intracellular signaling pathways in human conjunctival epithelial cells adherent to laminin. In addition, the purpose was to compare the phosphorylation kinetics of signaling intermediates in cells adherent to different laminin isoforms. Cell adhesion assays, integrin clustering experiments, and integrin function blocking experiments demonstrated that beta1 but not beta4 integrin mediated human conjunctival epithelial cell adhesion to placental laminin isoforms (laminin-10/11) and induced focal adhesion kinase (FAK) tyrosine phosphorylation. Western blot analysis of cell lysates adherent to placental laminin showed that the tyrosine phosphorylation of p130Cas and FAK was maximally above constitutive levels after 60 min. In cells adherent to EHS laminin (laminin-1), the tyrosine phosphorylation kinetics of tensin, p130Cas, FAK and unknown proteins of 138 kDa and 110 kDa were similar, and peaked above constitutive levels after 30 min. Tyrosine phosphorylation of a 70 kDa protein was induced by cell adhesion to EHS laminin after 5 min, and phosphorylation peaked at 15 min. In contrast, the tyrosine phosphorylation of the 70 kDa protein was undetected in cells adherent to placental laminin. Erk-1 phosphorylation and activation was not differentially modulated by conjunctival epithelial cell adhesion to laminins. However, phosphorylation and activation kinetics of Erk-2 in cells adherent to placental laminin was similar to that observed for FAK and p130Cas. Erk-2 phosphorylation and activation was essentially undetectable in cells adherent to EHS laminin. These observations suggest that human conjunctival epithelial cell adhesion to different laminin isoforms activates different intracellular signaling pathways, and provides support for the hypothesis that extracellular matrix molecules can modulate ocular surface epithelial cell differentiation via alternate signaling pathways.
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Affiliation(s)
- L Lin
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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5
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Abstract
PURPOSE To analyze alpha-integrin mediated adhesion of human corneal epithelial cells to placental and EHS laminin isoforms. METHODS Western blot analysis was used to partially characterize commercially available preparations of laminin isolated from the mouse EHS sarcoma and from human placenta. Using the human corneal epithelial cell line HCE-T, adhesion to laminin isoforms and fibronectin was determined using a colorimetric adhesion assay. alpha-integrin sub-unit modulation of corneal epithelial cell interaction with laminin isoforms was analyzed using immunofluorescence microscopy and adhesion assays incorporating functional blocking antibodies. RESULTS In short-term adhesion assays, the preferred substrate for HCE-T attachment is placental laminin. Immunofluorescence microscopy reveals that alpha-integrin protein localization patterns are not significantly different in HCE-T interacting with EHS or placental laminin. However, in short-term assays alpha3 integrin plays a major role, and alpha2 integrin a minor role, in mediating HCE-T adhesion to laminin. alpha6 integrin does not appear to mediate adhesion to either substrate. CONCLUSIONS These studies demonstrate that human corneal epithelial cells are capable of rapid adhesion to, and enhanced spreading on, laminin isoforms not characteristically resident in the adult corneal basement membrane. This characteristic of human corneal epithelium may explain, at least in part, why amniotic membrane transplantation is proving to be clinically useful for human ocular surface reconstruction.
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Affiliation(s)
- M A Kurpakus
- Wayne State University School of Medicine Department of Anatomy and Cell Biology USA Michigan, Detroit, MI 48201, USA.
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6
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Narumi K, Inoue A, Tanaka M, Isemura M, Shimo-Oka T, Abe T, Nukiwa T, Satoh K. Inhibition of experimental metastasis of human fibrosarcoma cells by anti-recombinant 37-kDa laminin binding protein antibody. Jpn J Cancer Res 1999; 90:425-31. [PMID: 10363581 PMCID: PMC5926078 DOI: 10.1111/j.1349-7006.1999.tb00765.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The laminin binding protein of 37 kDa (37LBP) is regarded as a precursor protein of the high-affinity 67-kDa laminin receptor (67LR). Expression of 67LR/37LBP is well correlated with biological aggressiveness of cancer, particularly with invasive and metastatic potential. To investigate in detail the role of 37LBP in cancer cells, we synthesized recombinant 37LBP (r37LBP) as a fusion protein and generated an IgG-type polyclonal antibody P4G against r37LBP. Western blot analysis with P4G showed a single band of 67LR under both nonreducing and reducing conditions using cell extract of human fibrosarcoma cells HT1080. It was shown that P4G inhibited cell attachment to immobilized laminin in a dose-dependent manner. Further, the intravenous injection of HT1080 cells pretreated with P4G, compared with that of cells pretreated with normal rabbit serum, resulted in a reduced number of experimental metastases (3.3+/-5.1 vs. 58.0+/-38.0 nodules per mouse, respectively) (P<0.005). These results suggest that P4G inhibits the colonization and growth of HT1080 cells in the lungs of mice, and that the blocking of r37LBP with the specific antibody P4G may offer a potential strategy for preventing cancer metastasis.
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Affiliation(s)
- K Narumi
- Department of Respiratory Oncology and Molecular Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai
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7
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Abstract
Laminins are a family of multifunctional macromolecules, ubiquitous in basement membranes, and represent the most abundant structural noncollagenous glycoproteins of these highly specialised extracellular matrices. Their discovery started with the difficult task of isolating molecules produced by cultivated cells or extracted from tissues. The development of molecular biology techniques has facilitated and accelerated the identification and the characterisation of new laminin variants making it feasible to identify full-length polypeptides which have not been purified. Further, genetically engineered laminin fragments can be generated for studies of their structure-function relationship, permitting the demonstration that laminins are involved in multiple interactions with themselves, with other components of the basal lamina, and with cells. It endows laminins with a central role in the formation, the architecture, and the stability of basement membranes. In addition, laminins may both separate and connect different tissues, i.e. the parenchymal and the interstitial connective tissues. Laminins also provide adjacent cells with a mechanical scaffold and biological information either directly by interacting with cell surface components, or indirectly by trapping growth factors. In doing so they trigger and control cellular functions. Recently, the structural and biological diversity of the laminins has started to be elucidated by gene targeting and by the identification of laminin defects in acquired or inherited human diseases. The consequent phenotypes highlight the pivotal role of laminins in determining heterogeneity in basement membrane functions.
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Affiliation(s)
- M Aumailley
- Institut für Biochemie II, Medical Faculty, Cologne, Germany.
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8
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Pennington ME, Lam KS, Cress AE. The use of a combinatorial library method to isolate human tumor cell adhesion peptides. Mol Divers 1996; 2:19-28. [PMID: 9238629 DOI: 10.1007/bf01718696] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Tumor cell progression is dependent in part on the successful adhesive interactions of the cells with the extracellular matrix. In this study, a new approach is described to isolate linear peptide ligand candidates involved in cellular adhesion. A synthetic combinatorial peptide library based on the 'one-bead-one-peptide' concept was incubated with live human prostate cancer cells for 90 min at 37 degrees C. The peptide bead coated with a monolayer of cells was then isolated for microsequencing. The DU145 (DU-H) cells were chosen since they have been previously characterized as containing elevated levels of a laminin receptor for cell adhesion, the alpha 6 beta 1 integrin on the cell surface. The use of a function-blocking antibody (GoH3) allows for the detection of peptides which are alpha 6-specific ligand candidates. From two different libraries (linear 9-mer and 11-mer) of a total of 1,500,000 beads, 68 peptide beads containing attached cells were isolated. These positive beads were then retested to determine the ability of the GoH3 antibody to block binding of the cells to the peptide beads. The alpha 6 integrin candidate peptide beads (five in total) were recovered and two of the beads were microsequenced. These two peptides, RU-1 (LNIVS-VNGRHX) and RX-1 (DNRIRLQAKXX), resemble the previously reported active peptide sequences (GD-2 and AG-73) from native laminin. The RU-1, RX-1 and AG-73 peptides were tested for their ability to support cell attachment and to bind the cell surface of DU-H prostate carcinoma cells in suspension using fluorescence-activated cell-sorting (FACS) analysis. Both RU-1 and AG-73 peptides supported cellular attachment within 1 h. In contrast, after 1 h, EHS laminin supported both cellular attachment and spreading. The RX-1 peptide exhibited only weak binding to the DU-H prostate carcinoma cells. FACS analysis indicated that AG-73 peptide attached to tumor cell surfaces over a range of concentrations, whereas the RU-1 peptide showed a homogeneous concentration required for attachment. The described strategy for screening a random peptide library offers three advantages: (i) ligands for conformationally sensitive receptors of adhesion can be isolated using live cells; (ii) specific binding can be selected for using function-blocking antibodies; and (iii) peptides supporting adhesion independent of spreading properties can be distinguished. In principle, specific adhesive peptides without prior knowledge of the sequence could be isolated for any epithelial cell surface receptor for which a function-blocking reagent is available.
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Affiliation(s)
- M E Pennington
- Department of Radiation Oncology, University of Arizona, Tucson 85824, USA
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9
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Perris R, Brandenberger R, Chiquet M. Differential neural crest cell attachment and migration on avian laminin isoforms. Int J Dev Neurosci 1996; 14:297-314. [PMID: 8842806 DOI: 10.1016/0736-5748(96)00015-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A number of laminin isoforms have recently been identified and proposed to exert different functions during embryonic development. In the present study, we describe the purification and partial characterization of several isoforms isolated from chick heart and gizzard, and provide data on the molecular mechanisms underlying the interaction of avian neural crest cells with these molecules in vitro. Laminins extracted from heart and gizzard tissues were separated by gel filtration and purified to homogeneity by sequential lectin and immunoaffinity chromatography by utilizing monoclonal antibodies directed against the avian alpha 2, beta 2 and gamma 1 laminin chains. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) banding pattern of the polypeptide complexes obtained and immunoblotting with polyclonal antisera allowed the identification of Laminin-2 (alpha 2 beta 1 gamma 1), Laminin-4 (alpha 2 beta 2 gamma 1), and laminins comprising the beta 1, beta 2 and gamma 1 chains associated with a shorter alpha chain which, in SDS-PAGE, co-migrate with the beta/gamma complex in the 200 kDa region. These latter laminins, which are here arbitrarily denoted Laminin-alpha x (heart tissue) and Laminin-G (gizzard tissue), are somewhat distinct in their apparent molecular weight, are differentially associated with nidogen, and appear as "T"-shaped particles similar to Laminin-6 and Laminin-7 when analyzed by transmission electron microscopy following rotary shadowing. In contrast, the avian Laminin-2 and Laminin-4 isoforms exhibit the characteristic cruciform shape described previously for their mammalian counterparts. Isolated neural crest cells differentially attached and migrated on these laminin isoforms, showing a clear preference for Laminin-G. Similarly to the EHS Laminin-1, neural crest cells recognized all avian isoforms through their alpha 1 beta 1 integrin, shown previously to be the primary laminin-binding receptor on these cells. Neural crest cell interaction with the avian laminins was dependent upon maintenance of the secondary and tertiary structure of the molecules, as shown by the marked reduction in cell attachment and migration upon disruption of the alpha-helical coiled-coil structure of their constituent chains. The results demonstrate that different laminin isoforms may be differentially involved in the regulation of neural crest cell migration and suggest that this regulation operates through interaction of the cells with a structurally conserved cell binding site recognized by the alpha 1 beta 1 integrin.
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Affiliation(s)
- R Perris
- Reference Center for Oncology, Division for Experimental Oncology 2, Aviano (PN), Italy
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10
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Giese A, Rief MD, Tran NL, Berens ME. Specific attachment and migration of human astrocytoma cells on human but not murine laminin. Glia 1995; 13:64-74. [PMID: 7751057 DOI: 10.1002/glia.440130108] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Attachment sites and biological functions of laminin isolated from murine EHS sarcoma have been well studied. Recently several variants of laminin including human placental laminin have been shown to be distinct from EHS-laminin. This study was undertaken to determine attachment, proliferation, and migration phenomena of human astrocytoma cell lines to human and murine sarcoma EHS-laminin. Using short-term attachment assays human placental laminin was shown to be the better substrate for cell adhesion. EHS-laminin mediated approximately 30-50% of the effect observed on human laminin. The astrocytoma cells expressed beta 1, beta 3, and beta 4 subunit mRNA as determined by RT-PCR. Anti-beta 1 antibodies blocked adhesion to EHS-laminin, but antibodies against beta 1, beta 4, and alpha v subunits were all ineffective in blocking adhesion to human laminin. A migration assay showed that astrocytoma cells on human laminin dispersed from a central seeding area, while cells on EHS-laminin remained where they were seeded. The pattern of dispersion could not be accounted for by changes in growth rates of astrocytoma cells on the different proteins, since both cell lines grew equally well on the two laminins. We conclude that unique epitopes on human laminin are recognized by novel receptors on human astrocytoma cells which confer a migratory phenotype to the cells.
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Affiliation(s)
- A Giese
- Neuro-Oncology Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013-4496, USA
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11
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Calof AL, Campanero MR, O'Rear JJ, Yurchenco PD, Lander AD. Domain-specific activation of neuronal migration and neurite outgrowth-promoting activities of laminin. Neuron 1994; 13:117-30. [PMID: 8043273 DOI: 10.1016/0896-6273(94)90463-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The ECM glycoprotein laminin has profound and varied actions on neurons in vitro. Little is known about how laminin's multiple domains and receptor-binding sites interact in determining its overall effects. Here, it is shown that laminin's ability to promote migration of olfactory epithelium neuronal cells maps to distal long arm domain E8 and is mediated by alpha 6 beta 1 integrin. Surprisingly, treatment of laminin with antibodies against its short arms (domains E1' or P1') uncovered a new neuronal migration-promoting activity, mediated by a beta 1 integrin other than alpha 6 beta 1. Laminin treated with anti-short arm antibodies also promoted beta 1 integrin-dependent neurite outgrowth from late embryonic retinal neurons, which are normally unresponsive to laminin. These "antibody-induced" migration and neurite outgrowth activities mapped to laminin's distal long arm, far from the site(s) of antibody binding. Evidence is presented that the induced activities are not actually cryptic in laminin, but are suppressed by an activity that is located in laminin's P1' domain and that may be lacking in the laminin homolog merosin.
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Affiliation(s)
- A L Calof
- Department of Biological Sciences, University of Iowa, Iowa City 52242
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12
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Delwel GO, de Melker AA, Hogervorst F, Jaspars LH, Fles DL, Kuikman I, Lindblom A, Paulsson M, Timpl R, Sonnenberg A. Distinct and overlapping ligand specificities of the alpha 3A beta 1 and alpha 6A beta 1 integrins: recognition of laminin isoforms. Mol Biol Cell 1994; 5:203-15. [PMID: 8019006 PMCID: PMC301026 DOI: 10.1091/mbc.5.2.203] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The ligand specificity of the alpha 3A beta 1 integrin was analyzed using K562 cells transfected with full-length alpha 3A cDNA and was compared with that of alpha 6A beta 1 in similarly transfected K562 cells. Clones were obtained that showed comparable surface expression of either alpha 3A beta 1 or alpha 6A beta 1 integrins. Those expressing alpha 3A beta 1 attached to and spread on immunopurified human kalinin and cellular matrices containing human kalinin, which is a particular isoform of laminin. In addition, alpha 3A transfectants adhered to bovine kidney laminins possessing a novel A chain variant. Binding to kalinin was blocked by a monoclonal antibody against the A chain constituent of kalinin and adhesion to both kalinin and kidney laminins by anti-alpha 3 and beta 1 monoclonal antibodies. The alpha 3A transfected cells bound more strongly to kalinin and bovine kidney laminins after treatment with the beta 1 stimulatory antibody TS2/16. A distinctly weaker and activation-dependent adhesion of alpha 3A transfectants was observed on human placental laminins possessing the Am chain variant (merosin), and no adhesion occurred on bovine heart laminins and murine EHS tumor laminin. Further inactive substrates were fibronectin, nidogen, and collagen types IV and VI, indicating that the alpha 3A beta 1 integrin is a much less promiscuous receptor than thought before. By contrast, alpha 6A transfected cells adhered to all laminin isoforms when stimulated with TS2/16. Adhesion also occurred only on bovine kidney laminins in the absence of TS2/16. These results demonstrate that both alpha 3A beta 1 and alpha 6A beta 1 integrins are typical laminin receptors but that their affinity and activation dependence for binding to various laminin isoforms differ considerably.
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Affiliation(s)
- G O Delwel
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam
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13
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Brown JC, Wiedemann H, Timpl R. Protein binding and cell adhesion properties of two laminin isoforms (AmB1eB2e, AmB1sB2e) from human placenta. J Cell Sci 1994; 107 ( Pt 1):329-38. [PMID: 8175920 DOI: 10.1242/jcs.107.1.329] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two isoforms of laminin were extracted from human placenta by neutral buffer containing EDTA, copurified through several steps and finally separated by Mono Q anion exchange chromatography. One variant consisted of disulphide-linked 340, 230 and 190 kDa subunits, which were identified by immunoblotting as Am, B1e and B2e chains. In the other variant, the B1e chain was replaced by B1s of 180 kDa. After rotary shadowing, both variants showed a similar cross-shaped structure. The nidogen content of these laminins was substoichiometric and variable (3-70%), indicating loss by endogenous proteolysis. Yet both human isoforms were able to bind mouse nidogen with an affinity (Kd approximately 0.5 nM) comparable to that of AeB1eB2e laminin from a mouse tumour. Since the binding site is known to be contributed by a single EGF-like motif of the B2e chain, this demonstrates that activity of this site is independent of chain assembly. Binding activity of both isoforms to collagen IV and the heparan sulphate proteoglycan perlecan was correlated to the nidogen content and could be enhanced by adding nidogen. Binding to heparin was only partial and heparin did not inhibit perlecan binding. This indicated a crucial role for nidogen in mediating the integration of these laminin isoforms into basement membranes. Variant AmB1sB2e showed calcium-dependent binding to fibulin-1, while only a little activity was found for AmB1eB2e. Both isoforms promoted adhesion and spreading of several cell lines. Adhesion could be completely inhibited by antibodies to the integrin beta 1 subunit but not, or only weakly, by antibodies against beta 3, alpha 2, alpha 3, alpha 5 and alpha 6 subunits. No inhibition was observed with an Arg-Gly-Asp-containing peptide.
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Affiliation(s)
- J C Brown
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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14
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Affiliation(s)
- R H Kramer
- Department of Stomatology, University of California, San Francisco 94143, USA
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15
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Expression and function of the cytoplasmic variants of the integrin alpha 6 subunit in transfected K562 cells. Activation-dependent adhesion and interaction with isoforms of laminin. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74468-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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16
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Petermann A, Fees H, Grenz H, Goodman SL, Sterzel RB. Polymerase chain reaction and focal contact formation indicate integrin expression in mesangial cells. Kidney Int 1993; 44:997-1005. [PMID: 8264159 DOI: 10.1038/ki.1993.341] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cultured kidney glomerular mesangial cells (MCs) allow the role of extracellular matrix (ECM) and growth factors in glomerular inflammatory disease to be studied. To investigate the potential of MCs to interact with matrix components, the expression of integrin mRNA in cultured MCs was examined by polymerase chain reaction (PCR), by Northern blotting and by immunofluorescence. In addition, the effect of matrix substrates on mRNA expression was assessed by PCR. Northern blots with cDNA probes to integrin alpha-chains revealed that MCs expressed alpha 1, alpha 3 and alpha 5 integrin mRNA. alpha 1 and alpha 3 were the major messages. No alpha 2, alpha 4 or alpha 6 were detectable. RT-PCR revealed that alpha 2 and alpha 6 were also expressed at low levels. The control cells, HT1080, expressed alpha 2, alpha 3, alpha 4, alpha 5 and alpha 6 mRNA, and Rugli expressed alpha 1, alpha 3 and alpha 5, supporting previous studies. Immunocytochemistry confirmed that alpha 1 beta 1, alpha 2 beta 1, and alpha 5 beta 1 integrins were expressed and that they were concentrated into focal adhesions (alpha 1 beta 1 on type I collagen and laminin; alpha 2 beta 1 on type I collagen; alpha 3 beta 1 on type I collagen, laminin and fibronectin; alpha 5 beta 1 on fibronectin). alpha 6 beta 1 was not detected in focal contacts. Attachment, spreading, and formation of talin and integrin containing focal contacts still occurred when endogenous protein synthesis was blocked with 30 micrograms.ml-1 cycloheximide.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Petermann
- Nephrology Research Laboratory, Medizinische Klinik IV, University of Erlangen-Nürnberg, Germany
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17
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Affiliation(s)
- D S Tuckwell
- School of Biological Sciences, University of Manchester, UK
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18
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Grenz H, Carbonetto S, Goodman SL. Alpha 3 beta 1 integrin is moved into focal contacts in kidney mesangial cells. J Cell Sci 1993; 105 ( Pt 3):739-51. [PMID: 8408301 DOI: 10.1242/jcs.105.3.739] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The movement of integrins into focal adhesive structures accompanies cell attachment to extracellular matrix. The kinetics of incorporation of integrins into focal contacts was studied during attachment to matrix of mesangial cells of the kidney glomerulus. On collagen, fibronectin, laminin and vitronectin, the number and intensity of talin-focal contacts increased with time. Talin-containing focal contacts were present in mesangial cells within 2 h of plating and in control cells (HT1080 and Rugli) within 1 h. Integrin alpha-chains colocalized with talin, dependent on the matrix substrate. The attachment, spreading and organization of integrin into focal contacts was not affected when endogenous protein synthesis was suppressed with cycloheximide. In Rugli, alpha 1 beta 1 organized into focal contacts on collagen and laminin, while in HT1080 alpha 2 beta 1 organized on collagen type I, alpha 5 beta 1 on fibronectin, alpha 6 beta 1 on laminin, and alpha 3 beta 1 and alpha 4 beta 1 were diffusely distributed on all substrates. These distributions mirrored the usage and expression patterns previously established for integrins in these cells and was as predicted from the literature. In mesangial cells, however, alpha 3 beta 1 was also organized into prominent focal contact arrays on collagen, fibronectin, EHS and human placental laminins, but not on vitronectin, while alpha 6 beta 1 was not organized. Initial attachment and spreading of mesangial cells was absolutely dependent on divalent cations. Mg2+ and Mn2+ supported attachment on all substrates, while Ca2+ stimulated attachment on laminin (E8), fibronectin and vitronectin. The data suggest that the functional integrins on mesangial cells include alpha 1 beta 1 (on collagen and laminin) alpha 2 beta 1 (on collagen), alpha 5 beta 1 (on fibronectin) and alpha V beta 3 (on vitronectin). However, mesangial cells do not use alpha 6 beta 1 on laminin, and the data support a role for alpha 3 beta 1 as putative receptor for fibronectin, collagen and laminin.
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Affiliation(s)
- H Grenz
- Nephrology Research Laboratory, Medical Clinic IV, University of Erlangen-Nürnberg, Germany
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Affiliation(s)
- M Weber
- Medical Department IV, University Erlangen-Nürnberg, Germany
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Goodman SL. Alpha 6 beta 1 integrin and laminin E8: an increasingly complex simple story. Kidney Int 1992; 41:650-6. [PMID: 1533429 DOI: 10.1038/ki.1992.100] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- S L Goodman
- Nephrology Research Laboratory, University of Erlangen-Nürnberg, Germany
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Skeletal myoblasts utilize a novel beta 1-series integrin and not alpha 6 beta 1 for binding to the E8 and T8 fragments of laminin. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54324-6] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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