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  • Human laminin isolated in a nearly intact, biologically active form from placenta by limited proteolysis. 6415055

    A protein with properties of laminin has been isolated from human placental extracts by using monoclonal antibodies. Placental tissue was extracted with 0.5 M NaCl and high molecular weight proteins were isolated from the extract by salt precipitation and gel filtration on Sepharose 6B. The resulting protein fraction which contained material cross-reactive with anti-sera to rat laminin was used as immunogen to prepare hybridomas. Thirteen hybrids produced antibodies which reacted with basement membrane-associated antigens in indirect immunofluorescence of tissues. One of these, 4E10, was characterized in detail. This monoclonal antibody reacted with human laminin as shown by several lines of evidence. Immunoprecipitation from metabolically labeled culture media of a human amniotic epithelial cell line with the 4E10 antibody followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed polypeptides with Mr similar to those of rat laminin. Immunochromatography of placental extracts obtained by limited pepsin digestion yielded material with main polypeptides at 160 and 130 kilodaltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis after reduction. These peptic fragments cross-reacted with rat laminin in immunodiffusion and enzyme immunoassay, and a polyclonal antiserum against the fragments reacted with basement membranes in tissues in a manner identical with the 4E10 antibody. Electron microscopic images of the human peptic fragments showed structures similar to the cross-shaped images of murine laminins, although the short arms were truncated to various degrees or even absent. The isolated peptic fragments also displayed biological activity similar to that of murine laminins in that the outgrowth of neurites by neuronal cells was promoted on plates coated with the fragments.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • Laminin α4 deficient mice exhibit decreased capacity for adipose tissue expansion and weight gain. 25310607

    Obesity is a global epidemic that contributes to the increasing medical burdens related to type 2 diabetes, cardiovascular disease and cancer. A better understanding of the mechanisms regulating adipose tissue expansion could lead to therapeutics that eliminate or reduce obesity-associated morbidity and mortality. The extracellular matrix (ECM) has been shown to regulate the development and function of numerous tissues and organs. However, there is little understanding of its function in adipose tissue. In this manuscript we describe the role of laminin α4, a specialized ECM protein surrounding adipocytes, on weight gain and adipose tissue function. Adipose tissue accumulation, lipogenesis, and structure were examined in mice with a null mutation of the laminin α4 gene (Lama4-/-) and compared to wild-type (Lama4+/+) control animals. Lama4-/- mice exhibited reduced weight gain in response to both age and high fat diet. Interestingly, the mice had decreased adipose tissue mass and altered lipogenesis in a depot-specific manner. In particular, epididymal adipose tissue mass was specifically decreased in knock-out mice, and there was also a defect in lipogenesis in this depot as well. In contrast, no such differences were observed in subcutaneous adipose tissue at 14 weeks. The results suggest that laminin α4 influences adipose tissue structure and function in a depot-specific manner. Alterations in laminin composition offers insight into the roll the ECM potentially plays in modulating cellular behavior in adipose tissue expansion.
    Document Type:
    Reference
    Product Catalog Number:
    AB756P
    Product Catalog Name:
    Anti-Collagen Antibody, Type IV

  • Laminin forms an independent network in basement membranes. 1577869

    Laminin self-assembles in vitro into a polymer by a reversible, entropy-driven and calcium-facilitated process dependent upon the participation of the short arm globular domains. We now find that this polymer is required for the structural integrity of the collagen-free basement membrane of cultured embryonal carcinoma cells (ECC) and for the supramolecular organization and anchorage of laminin in the collagen-rich basement membrane of the Engelbreth-Holm-Swarm tumor (EHS). First, low temperature and EDTA induced the dissolution of ECC basement membranes and released approximately 80% of total laminin from the EHS basement membrane. Second, laminin elastase fragments (E4 and E1') possessing the short arm globules of the B1, B2, and A chains selectively acted as competitive ligands that dissolved ECC basement membranes and displaced laminin from the EHS basement membrane into solution. The fraction of laminin released increased as a function of ligand concentration, approaching the level of the EDTA-reversible pool. The smaller (approximately 20%) residual pool of EHS laminin, in contrast, could only be effectively displaced by E1' and E4 if the collagenous network was first degraded with bacterial collagenase. The supramolecular architecture of freeze-etched and platinum/carbon replicated reconstituted laminin gel polymer, ECC, and collagenase-treated EHS basement membranes were compared and found to be similar, further supporting the biochemical data. We conclude that laminin forms a network independent of that of type IV collagen in basement membranes. Furthermore, in the EHS basement membrane four-fifths of laminin is anchored strictly through noncovalent bonds between laminin monomers while one-fifth is anchored through a combination of these bonds and laminin-collagen bridges.
    Document Type:
    Reference
    Product Catalog Number:
    06-1119

  • Laminin receptor involvement in the anti-angiogenic activity of pigment epithelium-derived factor. 19224861

    Pigment epithelium-derived factor (PEDF) is a multifunctional protein with neurotrophic, anti-oxidative, and anti-inflammatory properties. It is also one of the most potent endogenous inhibitors of angiogenesis, playing an important role in restricting tumor growth, invasion, and metastasis. Studies show that PEDF binds to cell surface proteins, but little is known about how it exerts its effects. Recently, research identified phospholipase A(2)/nutrin/patatin-like phospholipase domain-containing 2 as one PEDF receptor. To identify other receptors, we performed yeast two-hybrid screening using PEDF as bait and discovered that the non-integrin 37/67-kDa laminin receptor (LR) is another PEDF receptor. Co-immunoprecipitation, His tag pulldown, and surface plasmon resonance assays confirmed the interaction between PEDF and LR. Using the yeast two-hybrid method, we further restricted the LR-interacting domain on PEDF to a 34-amino acid (aa) peptide (aa 44-77) and the PEDF-interacting domain on LR to a 91-aa fragment (aa 120-210). A 25-mer peptide named P46 (aa 46-70), derived from 34-mer, interacts with LR in surface plasmon resonance assays and binds to endothelial cell (EC) membranes. This peptide induces EC apoptosis and inhibits EC migration, tube-like network formation in vitro, and retinal angiogenesis ex vivo, like PEDF. Our results suggest that LR is a real PEDF receptor that mediates PEDF angiogenesis inhibition.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1059
    Product Catalog Name:
    Anti-Pigment Epithelium Derived Factor Antibody, clone 10F12.2

  • Laminin and type VII collagen distribution in different types of human lung carcinoma: correlation with expression of keratins 14, 16, 17 and 18. 1374358

    The expression patterns of basement membrane components and keratin intermediate filament proteins were studied in normal human bronchial epithelium and 56 lung carcinomas using monoclonal antibodies to laminin, type VII collagen and the individual keratins 14, 16, 17 and 18. In normal lung, laminin and type VII collagen were present between the epithelium and the lamina propria of bronchi and bronchioles. Keratin 14 was expressed in the basal cells, keratin 17 in the basal and some suprabasal cells and keratin 18 in the columnar cells of the bronchi and bronchioles. Keratin 16 was not present in normal bronchial epithelium. Laminin was found in all subtypes of lung carcinoma, but type VII collagen was present only in squamous cell carcinomas, where it showed a reduction in expression with decreasing differentiation. Type VII collagen was not identified in adenocarcinomas, small cell carcinomas or carcinoids. Antibodies to basal cell keratins 14 and 17 also displayed positivity only in squamous cell carcinomas, although no correlation with the degree of differentiation could be observed. Keratin 16 appeared to be a marker of the squamous phenotype, rather than of hyperproliferation. The keratin 18 marker for columnar epithelial cells showed a reaction pattern opposite to that of the basal cell keratins, being extensively present in adenocarcinomas, small cell carcinomas and carcinoids, with less expression in squamous cell carcinomas. This study shows a correlation between the presence of type VII collagen and the basal cell keratins 14 and 17, and a negative correlation between these components and keratin 18. These findings are likely to be useful in identifying lung cancer subtypes.
    Document Type:
    Reference
    Product Catalog Number:
    MAB3232
    Product Catalog Name:
    Anti-Cytokeratin 14 Antibody, clone RCK107

  • Laminin isoforms 8 and 10 are primary components of the subendothelial basement membrane promoting interaction with neoplastic lymphocytes. 11196184

    To determine whether subendothelial laminins (LNs) could be implicated in the extravasation of neoplastic lymphocytes, we have examined the distribution of a number of LN isoforms in human vascular structures of adult individuals and have assayed the ability of the isolated LN molecules to promote adhesion of lymphoma and leukemic cells in vitro using a novel cell adhesion assay, CAFCA, Centrifugal Assay for Fluorescence-based Cell Adhesion (E. Giacomello et al., Biotechniques, 26: 758-762, 1999; P. Spessotto et al., Methods Mol. Biol., 139: 321-343, 2000). The use of previously characterized LN chain-specific antibodies showed that the vast majority of the smaller vascular compartments, known to correspond to sites of lymphocyte transmigration, expressed the subunits involved in the structuring of 9 of the 12 LN isoforms known to date. Eight LN isoforms (i.e., LN-1, -2, -4, -5, -8, -9, -10, and -11) and four naturally occurring LN complexes were isolated from various tissues and cultured cells by combined gel filtration, ion exchange, and immunoaffinity chromatographies, and the identity/composition of the isolated LNs/LN complexes was asserted by immunochemical means and amino-acid sequencing. Notwithstanding the widespread colocalization of LN isoforms, a panel of neoplastic B- and T-cell lines and lymphocytes isolated from patients affected by chronic lymphocytic B-cell leukemia attached preferentially and with high avidity to purified LN-8, purified LN-10, and LN-10-containing protein complexes, whereas lymphocytes derived from patients diagnosed with acute lymphocytic leukemia failed to bind to these LNs. All of the tested neoplastic lymphocytes failed to adhere to the isolated LN-1, LN-4, LN-9, and LN-11 and attached moderately well to purified LN-2 and LN-5. The interaction of transformed lymphocytes with LNs was cation-dependent and interchangeably mediated by the alpha3beta1 and alpha6beta1 integrins. The degree of engagement of the two LN receptors was dependent upon their relative levels of cell surface expression, whereas, irrespective of the phenotype, lymphocytes deprived of either of these receptors were incapable of LN binding. The findings suggest that LN-8 and LN-10 may act in an independent or complementary fashion as primary components of the endothelial basement membrane favoring the interaction of extravasating neoplastic lymphocytes. Thus, our results would demonstrate that different LN isoforms may evoke diverse cellular responses in different cell types and that this divergence may be the basis for the redundancy of LN distribution in a number of vascular structures.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1904
    Product Catalog Name:
    Anti-Laminin-1 A&B chains Antibody, cross region, clone AL-2

  • Expression of laminin isoforms, receptors, and binding proteins unique to nucleus pulposus cells of immature intervertebral disc. 19863388

    Intervertebral disc (IVD) disorders are believed to be related to aging-related cell loss and phenotypic changes, as well as biochemical and structural changes in the extracellular matrix of the nucleus pulposus (NP) region. Previously, we found that the laminin gamma1 chain was more highly expressed in immature NP porcine tissues, in parallel with the expression pattern for a laminin receptor, integrin alpha6 subunit, as compared to adjacent anulus fibrosus region. This result suggests that cell-matrix interactions may be unique to the immature NP. However, the identity of laminin isoforms specific to immature or mature NP tissues, their associated receptors, and functional significance are still poorly understood. In this study, we evaluated the zonal-specific expression of the laminin chains, receptors (i.e., integrins), and other binding proteins in immature tissue and isolated cells of rat, porcine and human intervertebral disc. Our goal was to reveal features of cellular environment and cell-matrix interactions in the immature NP. Results from both immunohistochemical staining and flow cytometry analysis found that NP cells expressed higher levels of the laminin alpha5 chain, laminin receptors (integrin alpha3, alpha6, beta4 subunit, and CD239), and related binding proteins (CD151), as compared to cells from adjacent anulus fibrosus. These differences suggest that laminin interactions with NP cells are distinct from that of the anulus fibrosus and that laminins may be important contributors to region-specific IVD biology. The revealed laminin isoforms, their receptors, and related binding proteins may be used as distinguishing features of these immature NP cells in the intervertebral disc.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • Laminin 511 partners with laminin 332 to mediate directional migration of Madin-Darby canine kidney epithelial cells. 22031290

    Sustained directional migration of epithelial cells is essential for regeneration of injured epithelia. Front-rear polarity of migrating cells is determined by local activation of a signaling network involving Cdc42 and other factors in response to spatial cues from the environment, the nature of which are obscure. We examined the roles of laminin (LM)-511 and LM-332, two structurally different laminin isoforms, in the migration of Madin-Darby canine kidney cells by suppressing expression of their α subunits using RNA interference. We determined that knockdown of LM-511 inhibits directional migration and destabilizes cell-cell contacts, in part by disturbing the localization and activity of the polarization machinery. Suppression of integrin α3, a laminin receptor subunit, in cells synthesizing normal amounts of both laminins has a similar effect as knockdown of LM-511. Surprisingly, simultaneous suppression of both laminin α5 and laminin α3 restores directional migration and cell-cell contact stability, suggesting that cells recognize a haptotactic gradient formed by a combination of laminins.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple

  • Laminin expression in the mouse lung increases with development and stimulates spontaneous organotypic rearrangement of mixed lung cells. 1292752

    The recent establishment of a role for laminin in mouse lung organogenesis (Schuger et al. 1990a,b, 1991) prompted us to study its expression in the developing lung. Laminin A and B chains were detected in the murine lung from the first hours of development onward. In situ hybridization of mRNA as well as SDS-PAGE studies of lung cells in monoculture indicated that both epithelium and mesenchyme produce complete laminin molecules. Quantitative analysis of the in situ hybridization studies showed a gradual increase in laminin expression during development which was further supported by immunohistochemistry and ELISA. The overall pattern of expression suggested that the effects of laminin in morphogenesis were not restricted to a particular stage of development. Furthermore, the increase in expression during late development supported a role for the molecule in the fetal lung, which was not previously established. We next determined whether the increase in laminin production modulated the behavior of fetal lung cells as compared with their embryonic counterparts. We previously showed that organotypic pattern formation does not occur in cultures of mixed embryonic lung cells unless exogenous laminin is added (Schuger et al., 1990b). Organotypic pattern formation is the result of cell sorting into epithelial and mesenchymal compartments and further rearrangement in a pattern resembling the tissue of origin. In the present study, we demonstrated that organotypic pattern formation occurs spontaneously in cultures of mixed fetal lung cells, which express high laminin levels. Pattern formation was abolished by antibodies to laminin. These studies suggest a correlation between laminin expression and the ability of lung cells in culture to reproduce normal tissue patterns. We conclude that laminin is critical for epithelial-mesenchymal recognition and further morphogenic interaction during both the embryonic and fetal stages of lung development.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple

  • Laminin alpha 2 (merosin)-deficient muscular dystrophy and demyelinating neuropathy in two cats. 11535231

    We report laminin alpha 2 (merosin) deficiency associated with muscular dystrophy and demyelinating neuropathy in two cats. The cats developed progressive muscle weakness, and atrophy. Either hypotonia or contractures resulted in recumbency, necessitating euthanasia. Muscle biopsies showed dystrophic changes including marked endomysial fibrosis, myofiber necrosis, variability of fiber size, and perimysial lipid accumulation. Immunohistochemistry showed that laminin alpha 2 chain was absent or reduced, while dystrophin and all the components of the dystrophin-associated glycoprotein complex were present and normal. One cat was examined in detail. Motor nerve conduction velocity (MNCV) was decreased, and ultrastructurally the peripheral nerves showed Schwann cell degeneration and demyelination. Brain imaging was not performed, but white matter changes were not apparent in the brain at necropsy. The disease in these cats is similar to primary or secondary merosin (laminin alpha 2)-deficient congenital muscular dystrophy (CMD) in humans and to dystrophia muscularis in mice.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1920
    Product Catalog Name:
    Anti-Laminin γ1 Antibody, clone 2E8