Here is a selection of publications where different laminin isoforms were used to create more authentic cell culture systems.

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  • Differentiation-dependent Expression of Laminin-8 (α4β1γ1) mRNAs in Mouse 3T3-L1 Adipocytes

    Niimi T., Kumagai C., Okano M., Kitagaw Y.Matrix Biology, 1997

    Here, the authors report that laminin-411 is the specific isoform of laminin synthesized in adipocytes. Reverse transcription-polymerase chain reaction (RT-PCR) of mRNA from mouse 3T3-L1 cells yielded amplified fragments only for α4β1γ1. Northern blots showed that the levels of α4,β1, and γ1 mRNAs increased 2.5-fold during adipose conversion of 3T3-L1 cells. A 1062 bp cDNA fragment cloned by RT-PCR demonstrated a polymorphism in the mouse a4 gene which would lead to five amino acid changes in the domain G.

  • Laminin a4 Deficient Mice Exhibit Decreased Capacity for Adipose Tissue Expansion and Weight Gain

    Vaicik M.K., Thyboll Kortesmaa J., Movérare-Skrtic S., Kortesmaa J., Soininen R., Bergström G., Ohlsson C., Chong L.Y., Rozell B., Emont M., Cohen R.N., Brey E.M., Tryggvason K.PLOS ONE, 2014

    Staining was performed for known adipose tissue BM proteins. In wild-type control mice the a2 and a4 chains of laminin were present in the BM surrounding mature adipocytes. Laminin a5 was not observed in mouse adipocyte BM. In this manuscript, we describe the role of laminin a4, 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 a4 gene (Lama42/2) and compared to wild-type (Lama4+/+) control animals. Lama42/2 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 a4 influences adipose tissue structure and function in a depot-specific manner.

  • Cell–Matrix Interactions in Mammary Gland Development and Breast Cancer

    Muschler J., Streuli C.H.Cold Spring Harb Perspect Biol., 2010

    Here, the authors argue that the interactions between mammary epithelial cells and their extracellular matrix (ECM) are crucial in the development and function of the tissue. Current strategies for treating breast cancer take advantage of our knowledge of the endocrine regulation and stromal–epithelial interactions. In addition, focusing on the microenvironmental influences that arise from cell-matrix interactions may open new opportunities for therapeutic intervention, suggesting a treatment where endocrine, growth factor, and cell-matrix interactions are targeted.

  • Regulation of mammary gland branching morphogenesis by the extracellular matrix and its remodeling enzymes

    Fata J.E., Werb Z. Bissell M.JBreast Cancer Res 2004

    A considerable body of research indicates that mammary gland branching morphogenesis is dependent, in part, on the extracellular matrix, affecting cell survival, polarity, proliferation, differentiation, adhesion, and migration. However, the precise mechanisms of ECM-directed mammary morphogenesis are not well understood and is discussed in this review. Mammary morphogenesis involves epithelial invasion of adipose tissue, a process akin to invasion by breast cancer cells, although the former is a highly regulated developmental process. How these morphogenic pathways are integrated into the normal gland and how they become dysregulated and subverted in the progression of breast cancer also remain largely unanswered questions.

  • Modifications in the basement membrane supramolecular structure of type IV collagen and laminin 5 organization facilitates skin derivative formation

    Alfayez M.Biomedical Research, 2010

    It has been suggested that laminin-332 is involved in the initiation of mammary gland development whilst laminin-511 is needed for maintaining the mammary bud down-growth into the dermis. In this study, the authors examine the proposed role(s) of the basement membrane proteins and their receptors during skin development using dissected mammary gland as a model. The pattern of expression of these molecules during skin formation was examined, utilizing collagen IV, laminin 5 and β4 or α6 integrin antibodies. The results suggest that these supramolecular structures play important roles in skin derivative development, more specifically mammary gland formation, and ease their resistance to skin derivatives down growth (invasion) into the underlying tissue.

  • Laminin and b1 Integrins Are Crucial for Normal Mammary Gland Development in the Mouse

    Klinowska T.C.M., Soriano J.V., Edwards G.M., Oliver J.M., Valentijn A.J., Montesano R., Streuli C.H.Developmental Biology, 1999

    Here, the authors examine the role of integrin-extracellular matrix interactions in the morphogenesis of ductal structures in vivo (mouse). End buds are surrounded by a basement membrane, which is shown to contain laminin-111 and collagen IV. Blocking B1 integrins dramatically reduced both the number of end buds per gland and the extent of the mammary ductal network, compared with controls. These effects were specific to the end buds since the rest of the gland architecture remained intact. Similar results were obtained with anti-laminin antibodies. In contrast, no effect on morphogenesis in vivo was seen with anti-a6 integrin antibody, suggesting that a6 is not the important partner for b1 in this system. They also show that integrins and hepatocyte growth factor (HGF) cooperate to regulate ductal morphogenesis. We propose that both laminin and b1 integrins are required to permit cellular traction through the stromal matrix and are therefore essential for maintaining end bud structure and function in normal pubertal mammary gland development.

  • Integrin-dependent response to laminin-511 regulates breast tumor cell invasion and metastasis

    Kusuma N., Denoyer D., Eble J.A., Redvers R.P., Parker B.S., Pelzer R. Anderson R.L., Pouliot N.International Journal of Cancer, 2011

    Laminin-511 is a potent adhesive and migratory substrate for metastatic breast tumor cells in vitro and its expression correlates with tumor grade and metastatic potential in vivo. Here the authors compared the metastatic potential of 4T1 mammary carcinoma cells to that of 4T1 variants isolated by repeated chemotactic migration toward LM-511 in vitro (4T1LMF4) followed by serial injection into the mammary gland and recovery of spontaneous metastases from the bone (4T1BM2). Variant subpopulations exhibited a distinct morphology on LM-511 and increased expression of b1 and b4 integrins compared to parental 4T1 cells. Importantly, mice inoculated with 4T1LMF4 and 4T1BM2 variants showed a 2.5- to 4-fold increase in the incidence of spontaneous metastasis to bone compared to 4T1 tumor-bearing mice. Functionally, 4T1BM2 variants were more adherent and more invasive toward LM-511 than parental 4T1 cells. Treatment of 4T1BM2 cells with lebein-1, a dis-integrin with selectivity toward LM-type integrin receptors, potently inhibited their migration and invasion toward LM-511. Similarly, a3b1 integrin-dependent migration and invasion of human MDA-MB-231 breast carcinoma cells toward LM-511 were significantly inhibited by lebein-1. Taken together, these results provide strong evidence that LM-511 contributes to the metastasis of breast tumors and suggest that targeting integrin-LM- 511 interactions with lebein-1 or other inhibitors of LM-511 receptors may have therapeutic potential for patients with advanced breast cancer.

  • Laminin α5 is necessary for submandibular gland epithelial morphogenesis and influences FGFR expression through β1 integrin signaling

    Rebustini I.T., Patel V.N., Stewart J.S, Layvey A. Georges-Labouesse E., Hoffman M.PDev Biol. 2007

    Here, the authors investigate the function of laminin α5 in mouse submandibular glands (SMGs). They show that although laminin α5 is not required for gland initiation, it plays an important role in initial cleft formation and epithelial morphogenesis; it is necessary for sublingual gland formation, and later in development is required for epithelial cell organization and lumen formation. The data suggest that laminin α5 controls SMG epithelial morphogenesis through β1 integrin signaling by regulating FGFR expression, which also reciprocally regulates the expression of Lama5 and that this regulation is independent of Lama1. Lama5-/- SMGs have a striking phenotype: epithelial clefting is delayed, although proliferation occurs; there is decreased FGFR1b and FGFR2b, but no difference in Lama1 expression; later in development, epithelial cell organization and lumen formation are disrupted. In wild-type SMGs α5 and α1 are present in epithelial clefts but as branching begins α5 expression increases while α1 decreases. Lama5 siRNA decreased branching, p42 MAPK phosphorylation, and FGFR expression, and branching was rescued by FGF10. FGFR siRNA decreased Lama5 suggesting FGFR signaling provides positive feedback for Lama5 expression. Anti-β1 integrin antibodies decreased FGFR and Lama5 expression, suggesting that β1 integrin signaling provides positive feedback for Lama5 and FGFR expression. Interestingly, the Itga3-/-:Itga6-/- SMGs have a similar phenotype to Lama5-/-. Our findings suggest that laminin α5 controls mouse submandibular glands epithelial morphogenesis through β1 integrin signaling by regulating FGFR expression, which also reciprocally regulates the expression of Lama5. These data link changes in basement membrane composition during branching morphogenesis with FGFR expression and signaling.

  • Evidence for a Role of Tumor-Derived Laminin-511 in the Metastatic Progression of Breast Cancer

    Chia J., Kusuma N., Anderson R., Parker B., Bidwell b., Zamurs L., Nice E., Pouliot N. The American Journal of Pathology, 2007

    Here, the authors investigate the expression and function of alpha5 chain-containing laminins, laminin-521 and laminin-511, during metastatic progression. Expression of laminin-511/laminin-521 subunits was examined in genetically related breast tumor lines and corresponding primary tumors and metastases in a syngeneic mouse model. The results indicate that laminin-511 rather than laminin-111, -332, or -521 correlates with metastatic potential in mouse mammary tumors. Current evidence argues against a direct role for laminin-111 and laminin-332 in the late-stage progression of breast tumors because both isoforms are down-regulated in most advanced breast tumors, suggesting a tumor-suppressing role and it is unlikely that these isoforms are used directly by breast tumor cells to promote invasion and metastasis. Laminin-511 was a potent adhesive substrate for both murine and human breast carcinoma cells and promoted strong haptotactic responses in metastatic lines. Haptotaxis was mediated by alpha3 integrin in both MCF-7 and MDA-MB-231 cells and was strongly inhibited by blocking antibodies against this integrin subunit. However, whereas nonmetastatic MCF-7 cells migrated toward laminin-511 (primarily via a3β1 integrin), results suggest that this response is mediated by an as yet unidentified a3β integrin heterodimer in MDA-MB-231 cells. These results are consistent with earlier reports implicating a3 integrins in breast cancer progression and support the role of laminin-511 as a functional substrate regulating breast cancer metastasis.

  • Laminin-111 and the Level of Nuclear Actin Regulate Epithelial Quiescence via Exportin-6

    Fiore A.P.Z.P, Spencer V.A., Mori H., Carvalho H.F., Bissell M.J., Bruni-Cardoso A.Cell Reports, 2017

    N-actin levels control transcription and proliferation of normal mammary cells. Here, the authors show that laminin 111 (LN111) induces a drastic decrease of nuclear actin in human mammary epithelial cells in a process mediated by XPO6 and required for the acquisition of cellular quiescence. LN1111 attenuates PI3K, leading to the upregulation of XPO6 activity. The LN111/XPO6/N-actin pathway is abnormal in malignant cells that are unresponsive to LN111 and proliferate uncontrollably.