The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform
Kiyotoshi Sekiguchi - One of the best experts on this subject based on the ideXlab platform.
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brain α dystroglycan displays unique glycoepitopes and preferential binding to Laminin 10 11
FEBS Letters, 2006Co-Authors: Erin L Mcdearmon, Kiyotoshi Sekiguchi, Hironobu Fujiwara, Ariana C Combs, James M ErvastiAbstract:α-Dystroglycan was quantitatively enriched from mammalian brain based on its uniform reactivity with Vicia villosa agglutinin and resolved into sub-populations possessing or lacking the sulfated glucuronic acid epitope recognized by monoclonal antibody HNK-1. We generated a new monoclonal antibody specific for a glycoepitope on brain α-dystroglycan but absent from α-dystroglycan expressed in all other tissues examined. Finally, we found that Laminin-10/11 preferentially bound to brain α-dystroglycan compared to skeletal muscle α-dystroglycan. Our results suggest that tissue-specific glycosylation modifies the Laminin binding specificity of α-dystroglycan.
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membrane type 1 matrix metalloprotease cleaves Laminin 10 and promotes prostate cancer cell migration
Neoplasia, 2005Co-Authors: Elisabeth L Bair, Kiyotoshi Sekiguchi, Raymond B Nagle, Man Ling Chen, Kathy Mcdaniel, Anne E Cress, G T BowdenAbstract:Disruption of the extracellular matrix by proteases is crucial for tumor invasion. Laminin-10 (Ln-10) has previously been identified as a substrate for cell migration and cell adhesion, and is present in the basal lamina (BL) of both normal prostate and prostate cancer. Here, we investigate a role for membrane type 1 matrix metalloprotease (MT1-MMP) in modifying this Ln-10-rich BL. MT1-MMP is a transmembrane member of the MMP family that has been demonstrated to be upregulated as prostate cancer progresses from normal to prostate intraepithelial neoplasia to invasive cancer, suggesting a role for MT1-MMP in the invasion of prostate cancer. We show that MT1-MMP cleaves the α5 chain of purified human Ln-10 from its 350-kDa form into 310-, 190-, 160-, and 45-kDa fragments. This cleavage causes a decrease in DU-145 prostate cancer cell adhesion to purified Ln-10, and an increase in transmigration of DU-145 cells through cleaved Ln-10. We also show that prostate cancer cells expressing membrane-bound MT1-MMP cleave the α5 chain of Ln-10. Ln α5-chain cleavage is also observed in human prostate cancer tissues. These findings suggest that prostate cancer cells expressing high levels of MT1-MMP have increased invasive potential through their ability to degrade and invade Ln-10 barriers.
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potentiation of the ligand binding activity of integrin α3β1 via association with tetraspanin cd151
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Ryoko Nishiuchi, Yasuhiro Sumida, Noriko Sanzen, Yoshinao Wada, Shigeyuki Nada, Masato Okada, Junichi Takagi, Hitoshi Hasegawa, Kiyotoshi SekiguchiAbstract:CD151, one of the tetraspanins, forms a stable complex with integrin α3β1, the major Laminin receptor on the cell surface. We found that 8C3, an anti-CD151 mAb obtained by screening for reactivity with integrin α3β1–CD151 complexes, was capable of dissociating CD151 from integrin α3β1, thereby allowing us to deplete CD151 from purified integrin α3β1–CD151 complexes. The CD151-free integrin α3β1 thus obtained showed a significant reduction in its ability to bind to Laminin-10/11, a high-affinity ligand for integrin α3β1, with a concomitant reduction in its reactivity with mAb AG89, which recognizes activated β1-containing integrins. These results raised the possibility that the association of integrin α3β1 with CD151 potentiates the ligand-binding activity of the integrin through sustaining its activated conformation. In support of this possibility, the ligand-binding activity was restored when CD151-free integrin α3β1 was reassociated with purified CD151. 8C3-induced dissociation of CD151 from integrin α3β1 was also demonstrated on the surface of living cells by fluorescent resonance energy transfer imaging, accompanied by a concomitant reduction in the cell adhesion to Laminin-10/11-coated substrates. CD151 knock-down by RNA interference also resulted in a reduction in the adhesive activity of the cells. Taken together, these results indicate that CD151 association modulates the ligand-binding activity of integrin α3β1 through stabilizing its activated conformation not only with purified proteins but also in a physiological context.
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molecular dissection of the α dystroglycan and integrin binding sites within the globular domain of human Laminin 10
Journal of Biological Chemistry, 2004Co-Authors: Hiroyuki Ido, Ryoko Nishiuchi, Kenji Harada, Sugiko Futaki, Yoshitaka Hayashi, Yuko Natsuka, Yoshinao Wada, Ariana C Combs, James M Ervasti, Kiyotoshi SekiguchiAbstract:The adhesive interactions of cells with Laminins are mediated by integrins and non-integrin-type receptors such as α-dystroglycan and syndecans. Laminins bind to these receptors at the C-terminal globular domain of their α chains, but the regions recognized by these receptors have not been mapped precisely. In this study, we sought to locate the binding sites of Laminin-10 (α5β1γ1) for α3β1 and α6β1 integrins and α-dystroglycan through the production of a series of recombinant Laminin-10 proteins with deletions of the LG (Laminin G-like) modules within the globular domain. We found that deletion of the LG4–5 modules did not compromise the binding of Laminin-10 to α3β1 and α6β1 integrins but completely abrogated its binding to α-dystroglycan. Further deletion up to the LG3 module resulted in loss of its binding to the integrins, underlining the importance of LG3 for integrin binding by Laminin-10. When expressed individually as fusion proteins with glutathione S-transferase or the N-terminal 70-kDa region of fibronectin, only LG4 was capable of binding to α-dystroglycan, whereas neither LG3 nor any of the other LG modules retained the ability to bind to the integrins. Site-directed mutagenesis of the LG3 and LG4 modules indicated that Asp-3198 in the LG3 module is involved in the integrin binding by Laminin-10, whereas multiple basic amino acid residues in the putative loop regions are involved synergistically in the α-dystroglycan binding by the LG4 module.
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matrix metalloproteinase 2 is involved in a549 cell migration on Laminin 10 11
Biochemical and Biophysical Research Communications, 2002Co-Authors: Ryoko Nishiuchi, Kiyotoshi SekiguchiAbstract:We have reported that Laminin-10/11 strongly promotes migration of A549 human lung carcinoma cells by activating the alpha3beta1 integrin-dependent signaling pathway. To elucidate the mechanism involved, we investigated whether matrix metalloproteinases (MMPs) are involved in cell migration on Laminin-10/11. Here, we demonstrate that Laminin-10/11, but not fibronectin which does not greatly promote A549 cell movement, stimulated MMP-2 secretion approximately 3-fold. The cell migration-promoting activity of Laminin-10/11 was down-regulated by an MMP inhibitor. In addition, cell motility was significantly increased when cells adhered to a mixture of fibronectin and Laminin-10/11 with a concomitant decrease of focal contacts, compared with those adhering to fibronectin alone. The enhanced cell migration was partially suppressed by the MMP inhibitor. Furthermore, an anti-alpha3 integrin, but not an anti-alpha5 integrin, antibody induced the activated form of MMP-2. These data suggest that MMP-2 may play an important role in A549 cell migration on Laminin-10/11 through an alpha3beta1 integrin-dependent pathway.
Yamato Kikkawa - One of the best experts on this subject based on the ideXlab platform.
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Laminin 10 and lutheran blood group glycoproteins in adhesion of human endothelial cells
American Journal of Physiology-cell Physiology, 2006Co-Authors: Noora Vainionpaa, Jeffrey H Miner, Yamato Kikkawa, Kari Lounatmaa, Patricia Rousselle, Ismo VirtanenAbstract:Laminin α5-chain, a constituent of Laminins-10 and -11, is expressed in endothelial basement membranes. In this study we evaluated the roles of α5 Laminins and Lutheran blood group glycoproteins (L...
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the immortalized human corneal epithelial cells adhere to Laminin 10 by using lutheran glycoproteins and integrin α3β1
Experimental Eye Research, 2005Co-Authors: Sissi Hasenson, Jeffrey H Miner, Yamato Kikkawa, Patricia Rousselle, Marko Maatta, Timo Tervo, Ismo VirtanenAbstract:Abstract We studied the adhesion characteristics of immortalized human corneal epithelial (HCE) cells on purified human Laminin (Ln)-10 (α5β1γ1). Immunofluorescence studies with monoclonal antibodies (MAb) revealed the presence of Laminin α5 chain receptor Lutheran (Lu) in vivo on the basal cells of cornea and as punctate cell surface-confined reactivity on adhering and spread HCE cells, while α- and β-dystroglycans could not be found. Northern blot analysis showed the presence of 4.0 and 2.8 kb Lu transcripts in HCE cells. The results showed that Ln-10 induced adhesion and spreading of HCE cells without formation of focal adhesions. Quantitative adhesion assay showed that Lu together with integrin (Int) α 3 β 1 independently mediated the adhesion of HCE cells to Ln-10.
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integrin binding specificity of Laminin 10 11 Laminin 10 11 are recognized by alpha 3 beta 1 alpha 6 beta 1 and alpha 6 beta 4 integrins
Journal of Cell Science, 2000Co-Authors: Yamato Kikkawa, Noriko Sanzen, Hironobu Fujiwara, Arnoud Sonnenberg, Kiyotoshi SekiguchiAbstract:Laminin-10/11, the Laminin isoforms containing the alpha 5 chain, are major components of basement membranes of many fetal and adult tissues. Laminin-10/11 purified from the conditioned medium of human lung carcinoma cells were potent in mediating adhesion of the carcinoma cells in an integrin alpha 3 beta 1-dependent manner. To further define the type(s) of integrins involved in cell adhesion to Laminin-10/11, we examined the effects of a panel of function-blocking anti-integrin antibodies on the adhesion of different cell types to Laminin-10/11. Although anti-integrin beta 1 antibody inhibited the adhesion of all cell types tested, anti-alpha 3 antibody inhibited the adhesion of carcinoma and glioma cells but not fibroblastic cells. Adhesion of fibroblastic cells was inhibited, however, by a combination of anti-alpha 3 and anti-alpha 6 antibodies, suggesting that both alpha 3 beta 1 and alpha 6 beta 1 integrins function as Laminin-10/11 receptors in these cells. To explore this possibility, we examined the adhesion of K562 leukemic cells transfected with integrin alpha 3 or alpha 6 subunit to Laminin-10/11 or other Laminin isoforms. Laminin-10/11 were potent adhesive ligands for both the alpha 3 beta 11 and alpha 6 beta 1 transfectants, whereas Laminin-5 was the preferred ligand for the alpha 3 beta 1 transfectants. Upon stimulation with the activating anti-integrin beta 1 antibody, both transfectants became more adherent to the substratum regardless of the type of Laminins coated, although their preference for Laminin isoforms remained unaltered. K562 cells transfected with alpha 6 and beta 4 subunits were also capable of adhering to Laminin-10/11, indicating that integrin alpha 6 beta 4 is another receptor for Laminin-10/11. Even with lung carcinoma cells, the alpha 6-containing integrins partly contributed to adhesion to Laminin-10/11 at higher coating concentrations, although non-integrin receptor(s) might also be involved under such conditions. These results indicated that Laminin-10/11 are potent and versatile adhesive ligands in basement membranes capable of binding to both alpha 3 beta 1 and alpha 6 beta 1 integrins with high avidity and also to alpha 6 beta 4 integrin.
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integrin binding specificity of Laminin 10 11 Laminin 10 11 are recognized by α3β1 α6β1 and α6β4 integrins
2000Co-Authors: Yamato Kikkawa, Noriko Sanzen, Hironobu Fujiwara, Arnoud Sonnenberg, Kiyotoshi SekiguchiAbstract:Laminin-10/11, the Laminin isoforms containing the α5 chain, are major components of basement membranes of many fetal and adult tissues. Laminin-10/11 purified from the conditioned medium of human lung carcinoma cells were potent in mediating adhesion of the carcinoma cells in an integrin α3β1-dependent manner. To further define the type(s) of integrins involved in cell adhesion to Laminin10/11, we examined the effects of a panel of functionblocking anti-integrin antibodies on the adhesion of different cell types to Laminin-10/11. Although anti-integrin β1 antibody inhibited the adhesion of all cell types tested, anti-α3 antibody inhibited the adhesion of carcinoma and glioma cells but not fibroblastic cells. Adhesion of fibroblastic cells was inhibited, however, by a combination of anti-α3 and anti-α6 antibodies, suggesting that both α3β1 and α6β1 integrins function as Laminin-10/11 receptors in these cells. To explore this possibility, we examined the adhesion of K562 leukemic cells transfected with integrin α3 or α6 subunit to Laminin-10/11 or other Laminin isoforms. Laminin-10/11 were potent adhesive ligands for both the α3β1 and α6β1 transfectants, whereas Laminin-5 was the preferred ligand for the α3β1 transfectants. Upon stimulation with the activating antiintegrin β1 antibody, both transfectants became more adherent to the substratum regardless of the type of Laminins coated, although their preference for Laminin isoforms remained unaltered. K562 cells transfected with α6 and β4 subunits were also capable of adhering to Laminin-10/11, indicating that integrin α6β4 is another receptor for Laminin-10/11. Even with lung carcinoma cells, the α6-containing integrins partly contributed to adhesion to Laminin-10/11 at higher coating concentrations, although non-integrin receptor(s) might also be involved under such conditions. These results indicated that Laminin-10/11 are potent and versatile adhesive ligands in basement membranes capable of binding to both α3β1 and α6β1 integrins with high avidity and also to α6β4 integrin. SUMMARY
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isolation and characterization of Laminin 10 11 secreted by human lung carcinoma cells Laminin 10 11 mediates cell adhesion through integrin α3β1
Journal of Biological Chemistry, 1998Co-Authors: Yamato Kikkawa, Noriko Sanzen, Kiyotoshi SekiguchiAbstract:A panel of human tumor cell lines was screened for selective expression of Laminin α5 chain, a newly identified Laminin subunit comprising Laminin-10 (α5β1γ1) and -11 (α5β2γ1). The lung adenocarcinoma cell line A549 was found to express the α5 chain at relatively high levels but no detectable amounts of other α chains. The Laminin variants containing α5 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 α5 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-α5 chain monoclonal antibody capable of recognizing denatured α5 chain on immunoblots, whereas the 210-kDa chain was recognized by an anti-γ1 chain antibody. The purified α5 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 α3 or β1 subunit but not by those against α2 or α6 subunit, indicating that Laminin-10/11 is specifically recognized by integrin α3β1. Given the wide distribution of Laminin-10/11 in the basement membrane of various tissue types and dominant expression of integrin α3β1 in most epithelial cells, specific interaction of Laminin-10/11 with integrin α3β1 may play an important role in in vivo regulation of proliferation and differentiation of epithelial cells through the basement membrane.
Noriko Sanzen - One of the best experts on this subject based on the ideXlab platform.
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potentiation of the ligand binding activity of integrin α3β1 via association with tetraspanin cd151
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Ryoko Nishiuchi, Yasuhiro Sumida, Noriko Sanzen, Yoshinao Wada, Shigeyuki Nada, Masato Okada, Junichi Takagi, Hitoshi Hasegawa, Kiyotoshi SekiguchiAbstract:CD151, one of the tetraspanins, forms a stable complex with integrin α3β1, the major Laminin receptor on the cell surface. We found that 8C3, an anti-CD151 mAb obtained by screening for reactivity with integrin α3β1–CD151 complexes, was capable of dissociating CD151 from integrin α3β1, thereby allowing us to deplete CD151 from purified integrin α3β1–CD151 complexes. The CD151-free integrin α3β1 thus obtained showed a significant reduction in its ability to bind to Laminin-10/11, a high-affinity ligand for integrin α3β1, with a concomitant reduction in its reactivity with mAb AG89, which recognizes activated β1-containing integrins. These results raised the possibility that the association of integrin α3β1 with CD151 potentiates the ligand-binding activity of the integrin through sustaining its activated conformation. In support of this possibility, the ligand-binding activity was restored when CD151-free integrin α3β1 was reassociated with purified CD151. 8C3-induced dissociation of CD151 from integrin α3β1 was also demonstrated on the surface of living cells by fluorescent resonance energy transfer imaging, accompanied by a concomitant reduction in the cell adhesion to Laminin-10/11-coated substrates. CD151 knock-down by RNA interference also resulted in a reduction in the adhesive activity of the cells. Taken together, these results indicate that CD151 association modulates the ligand-binding activity of integrin α3β1 through stabilizing its activated conformation not only with purified proteins but also in a physiological context.
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Laminin 10 11 and fibronectin differentially regulate integrin dependent rho and rac activation via p130cas crkii dock180 pathway
Journal of Biological Chemistry, 2001Co-Authors: Yasuhiro Sumida, Noriko Sanzen, Kiyotoshi SekiguchiAbstract:Abstract The α5 chain-containing Laminin isoforms, Laminins-10 and -11 (Laminin-10/11), are the major components of the basement membrane, having potent cell-adhesive activity. We examined the cell-adhesive and integrin-mediated signaling activities of Laminin-10/11 in comparison to fibronectin, the best characterized extracellular adhesive ligand. We found that Laminin-10/11 are more active than fibronectin in promoting cell migration and preferentially activate Rac, not Rho, via the p130Cas-CrkII-DOCK180 pathway. Cells adhering to fibronectin develop stress fibers and focal contacts, whereas cells adhering to Laminin-10/11 do not, consistent with the high cell migration-promoting activity of Laminin-10/11. Pull-down assays of GTP-loaded Rac and Rho demonstrated the preferential activation of Rac on Laminin-10/11, in contrast to the activation of Rho on fibronectin. Activation of Rac by Laminin-10/11 was associated with the phosphorylation of p130Cas and an increased formation of a p130Cas-CrkII-DOCK180 complex. Cell migration on Laminin-10/11 was suppressed by the expression of either a dominant-negative Rac or CrkII mutants defective in p130Casor DOCK180 binding. This is the first report demonstrating a distinct activation of Rho family GTPases resulting from adhesion to different extracellular ligands.
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integrin binding specificity of Laminin 10 11 Laminin 10 11 are recognized by alpha 3 beta 1 alpha 6 beta 1 and alpha 6 beta 4 integrins
Journal of Cell Science, 2000Co-Authors: Yamato Kikkawa, Noriko Sanzen, Hironobu Fujiwara, Arnoud Sonnenberg, Kiyotoshi SekiguchiAbstract:Laminin-10/11, the Laminin isoforms containing the alpha 5 chain, are major components of basement membranes of many fetal and adult tissues. Laminin-10/11 purified from the conditioned medium of human lung carcinoma cells were potent in mediating adhesion of the carcinoma cells in an integrin alpha 3 beta 1-dependent manner. To further define the type(s) of integrins involved in cell adhesion to Laminin-10/11, we examined the effects of a panel of function-blocking anti-integrin antibodies on the adhesion of different cell types to Laminin-10/11. Although anti-integrin beta 1 antibody inhibited the adhesion of all cell types tested, anti-alpha 3 antibody inhibited the adhesion of carcinoma and glioma cells but not fibroblastic cells. Adhesion of fibroblastic cells was inhibited, however, by a combination of anti-alpha 3 and anti-alpha 6 antibodies, suggesting that both alpha 3 beta 1 and alpha 6 beta 1 integrins function as Laminin-10/11 receptors in these cells. To explore this possibility, we examined the adhesion of K562 leukemic cells transfected with integrin alpha 3 or alpha 6 subunit to Laminin-10/11 or other Laminin isoforms. Laminin-10/11 were potent adhesive ligands for both the alpha 3 beta 11 and alpha 6 beta 1 transfectants, whereas Laminin-5 was the preferred ligand for the alpha 3 beta 1 transfectants. Upon stimulation with the activating anti-integrin beta 1 antibody, both transfectants became more adherent to the substratum regardless of the type of Laminins coated, although their preference for Laminin isoforms remained unaltered. K562 cells transfected with alpha 6 and beta 4 subunits were also capable of adhering to Laminin-10/11, indicating that integrin alpha 6 beta 4 is another receptor for Laminin-10/11. Even with lung carcinoma cells, the alpha 6-containing integrins partly contributed to adhesion to Laminin-10/11 at higher coating concentrations, although non-integrin receptor(s) might also be involved under such conditions. These results indicated that Laminin-10/11 are potent and versatile adhesive ligands in basement membranes capable of binding to both alpha 3 beta 1 and alpha 6 beta 1 integrins with high avidity and also to alpha 6 beta 4 integrin.
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integrin binding specificity of Laminin 10 11 Laminin 10 11 are recognized by α3β1 α6β1 and α6β4 integrins
2000Co-Authors: Yamato Kikkawa, Noriko Sanzen, Hironobu Fujiwara, Arnoud Sonnenberg, Kiyotoshi SekiguchiAbstract:Laminin-10/11, the Laminin isoforms containing the α5 chain, are major components of basement membranes of many fetal and adult tissues. Laminin-10/11 purified from the conditioned medium of human lung carcinoma cells were potent in mediating adhesion of the carcinoma cells in an integrin α3β1-dependent manner. To further define the type(s) of integrins involved in cell adhesion to Laminin10/11, we examined the effects of a panel of functionblocking anti-integrin antibodies on the adhesion of different cell types to Laminin-10/11. Although anti-integrin β1 antibody inhibited the adhesion of all cell types tested, anti-α3 antibody inhibited the adhesion of carcinoma and glioma cells but not fibroblastic cells. Adhesion of fibroblastic cells was inhibited, however, by a combination of anti-α3 and anti-α6 antibodies, suggesting that both α3β1 and α6β1 integrins function as Laminin-10/11 receptors in these cells. To explore this possibility, we examined the adhesion of K562 leukemic cells transfected with integrin α3 or α6 subunit to Laminin-10/11 or other Laminin isoforms. Laminin-10/11 were potent adhesive ligands for both the α3β1 and α6β1 transfectants, whereas Laminin-5 was the preferred ligand for the α3β1 transfectants. Upon stimulation with the activating antiintegrin β1 antibody, both transfectants became more adherent to the substratum regardless of the type of Laminins coated, although their preference for Laminin isoforms remained unaltered. K562 cells transfected with α6 and β4 subunits were also capable of adhering to Laminin-10/11, indicating that integrin α6β4 is another receptor for Laminin-10/11. Even with lung carcinoma cells, the α6-containing integrins partly contributed to adhesion to Laminin-10/11 at higher coating concentrations, although non-integrin receptor(s) might also be involved under such conditions. These results indicated that Laminin-10/11 are potent and versatile adhesive ligands in basement membranes capable of binding to both α3β1 and α6β1 integrins with high avidity and also to α6β4 integrin. SUMMARY
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isolation and characterization of Laminin 10 11 secreted by human lung carcinoma cells Laminin 10 11 mediates cell adhesion through integrin α3β1
Journal of Biological Chemistry, 1998Co-Authors: Yamato Kikkawa, Noriko Sanzen, Kiyotoshi SekiguchiAbstract:A panel of human tumor cell lines was screened for selective expression of Laminin α5 chain, a newly identified Laminin subunit comprising Laminin-10 (α5β1γ1) and -11 (α5β2γ1). The lung adenocarcinoma cell line A549 was found to express the α5 chain at relatively high levels but no detectable amounts of other α chains. The Laminin variants containing α5 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 α5 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-α5 chain monoclonal antibody capable of recognizing denatured α5 chain on immunoblots, whereas the 210-kDa chain was recognized by an anti-γ1 chain antibody. The purified α5 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 α3 or β1 subunit but not by those against α2 or α6 subunit, indicating that Laminin-10/11 is specifically recognized by integrin α3β1. Given the wide distribution of Laminin-10/11 in the basement membrane of various tissue types and dominant expression of integrin α3β1 in most epithelial cells, specific interaction of Laminin-10/11 with integrin α3β1 may play an important role in in vivo regulation of proliferation and differentiation of epithelial cells through the basement membrane.
Ismo Virtanen - One of the best experts on this subject based on the ideXlab platform.
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unique basement membrane structure of human pancreatic islets implications for beta cell growth and differentiation
Diabetes Obesity and Metabolism, 2008Co-Authors: Timo Otonkoski, Meenal Banerjee, Olle Korsgren, Larseric Thornell, Ismo VirtanenAbstract:Basement membranes (BMs) are an important part of the physiological microenvironment of pancreatic islet cells. In mouse islets, beta-cells interact directly with BMs of capillary endothelial cells. We have shown that in the human islets, the capillaries are surrounded by a double BM both in foetal and adult tissues. The endocrine islet cells are facing a BM that is separate from the endothelia. Laminins are the functionally most important component of BMs. The only Laminin isoform present in the human endocrine islet BM is Laminin-511 (previously known as Laminin 10). The islet cells facing this BM have a strong and polarized expression of Lutheran glycoprotein, which is a well-known receptor for the Laminin alpha 5 chain. Dispersed human islet cells adhere to purified human Laminin-511 and the binding is equally effectively blocked by a soluble form of Lutheran as by antibody against integrin beta1. Our results reveal unique features of the BM structure of human islets, different from rodents. This information has potentially important implications for the generation of an optimal microenvironment for beta-cell function, proliferation and differentiation.
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Laminin 10 and lutheran blood group glycoproteins in adhesion of human endothelial cells
American Journal of Physiology-cell Physiology, 2006Co-Authors: Noora Vainionpaa, Jeffrey H Miner, Yamato Kikkawa, Kari Lounatmaa, Patricia Rousselle, Ismo VirtanenAbstract:Laminin α5-chain, a constituent of Laminins-10 and -11, is expressed in endothelial basement membranes. In this study we evaluated the roles of α5 Laminins and Lutheran blood group glycoproteins (L...
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the immortalized human corneal epithelial cells adhere to Laminin 10 by using lutheran glycoproteins and integrin α3β1
Experimental Eye Research, 2005Co-Authors: Sissi Hasenson, Jeffrey H Miner, Yamato Kikkawa, Patricia Rousselle, Marko Maatta, Timo Tervo, Ismo VirtanenAbstract:Abstract We studied the adhesion characteristics of immortalized human corneal epithelial (HCE) cells on purified human Laminin (Ln)-10 (α5β1γ1). Immunofluorescence studies with monoclonal antibodies (MAb) revealed the presence of Laminin α5 chain receptor Lutheran (Lu) in vivo on the basal cells of cornea and as punctate cell surface-confined reactivity on adhering and spread HCE cells, while α- and β-dystroglycans could not be found. Northern blot analysis showed the presence of 4.0 and 2.8 kb Lu transcripts in HCE cells. The results showed that Ln-10 induced adhesion and spreading of HCE cells without formation of focal adhesions. Quantitative adhesion assay showed that Lu together with integrin (Int) α 3 β 1 independently mediated the adhesion of HCE cells to Ln-10.
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segment specific but pathologic Laminin isoform profiles in human labial salivary glands of patients with sjogren s syndrome
Arthritis & Rheumatism, 2004Co-Authors: Mikael Laine, Ismo Virtanen, Tuula Salo, Yrjo T KonttinenAbstract:Objective To assess the Laminins in basement membrane of the labial salivary glands of patients with Sjogren's syndrome (SS) and healthy controls. Methods Labeling of Laminin α1–α5, β1, β2, γ1, and γ2 chains was performed using immunohistochemistry with chain-specific monoclonal antibodies and pattern recognition analysis of the labeled specimens. Results Laminin α1, α2, and α4 chains were detected exclusively in the acinar basement membranes, whereas Laminin α3, α5, β1, γ1, and γ2 chains were also detected in ductal basement membranes. Laminin β2 chain was not found. In patients with SS, Laminin α1 and α2 chains were weakly labeled, but Laminin α4 labeling was also intense in areas not infiltrated by lymphocytes. Pattern recognition analysis suggested that Laminin α1, α2, and α4 chains were associated with acinar cells, myoepithelial cells, and tissue damage/repair, respectively. Conclusion All salivary gland basement membranes signal through Laminin 5, Laminin 6, and Laminin 10 trimers, but acinar basement membranes also signal through Laminin 1, Laminin 2, and Laminin 8 trimers. Laminin α1 chain/Laminin 1 may play a central role in the maintenance of acinar cells in healthy glands. This possibility was supported by the finding of variable expression of Laminin α1 chain/Laminin 1 in acinar basement membrane and its weak expression in SS with acinar cell atrophy. The impairment of myoepithelial Laminin α2 chain/Laminin 2 in patients with SS indicates a double defect in the acinar compartment and pathologic extracellular matrix–to-cell signaling, which may contribute to structural deterioration and functional abnormality of the exocrine glands.
Hironobu Fujiwara - One of the best experts on this subject based on the ideXlab platform.
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brain α dystroglycan displays unique glycoepitopes and preferential binding to Laminin 10 11
FEBS Letters, 2006Co-Authors: Erin L Mcdearmon, Kiyotoshi Sekiguchi, Hironobu Fujiwara, Ariana C Combs, James M ErvastiAbstract:α-Dystroglycan was quantitatively enriched from mammalian brain based on its uniform reactivity with Vicia villosa agglutinin and resolved into sub-populations possessing or lacking the sulfated glucuronic acid epitope recognized by monoclonal antibody HNK-1. We generated a new monoclonal antibody specific for a glycoepitope on brain α-dystroglycan but absent from α-dystroglycan expressed in all other tissues examined. Finally, we found that Laminin-10/11 preferentially bound to brain α-dystroglycan compared to skeletal muscle α-dystroglycan. Our results suggest that tissue-specific glycosylation modifies the Laminin binding specificity of α-dystroglycan.
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integrin binding specificity of Laminin 10 11 Laminin 10 11 are recognized by alpha 3 beta 1 alpha 6 beta 1 and alpha 6 beta 4 integrins
Journal of Cell Science, 2000Co-Authors: Yamato Kikkawa, Noriko Sanzen, Hironobu Fujiwara, Arnoud Sonnenberg, Kiyotoshi SekiguchiAbstract:Laminin-10/11, the Laminin isoforms containing the alpha 5 chain, are major components of basement membranes of many fetal and adult tissues. Laminin-10/11 purified from the conditioned medium of human lung carcinoma cells were potent in mediating adhesion of the carcinoma cells in an integrin alpha 3 beta 1-dependent manner. To further define the type(s) of integrins involved in cell adhesion to Laminin-10/11, we examined the effects of a panel of function-blocking anti-integrin antibodies on the adhesion of different cell types to Laminin-10/11. Although anti-integrin beta 1 antibody inhibited the adhesion of all cell types tested, anti-alpha 3 antibody inhibited the adhesion of carcinoma and glioma cells but not fibroblastic cells. Adhesion of fibroblastic cells was inhibited, however, by a combination of anti-alpha 3 and anti-alpha 6 antibodies, suggesting that both alpha 3 beta 1 and alpha 6 beta 1 integrins function as Laminin-10/11 receptors in these cells. To explore this possibility, we examined the adhesion of K562 leukemic cells transfected with integrin alpha 3 or alpha 6 subunit to Laminin-10/11 or other Laminin isoforms. Laminin-10/11 were potent adhesive ligands for both the alpha 3 beta 11 and alpha 6 beta 1 transfectants, whereas Laminin-5 was the preferred ligand for the alpha 3 beta 1 transfectants. Upon stimulation with the activating anti-integrin beta 1 antibody, both transfectants became more adherent to the substratum regardless of the type of Laminins coated, although their preference for Laminin isoforms remained unaltered. K562 cells transfected with alpha 6 and beta 4 subunits were also capable of adhering to Laminin-10/11, indicating that integrin alpha 6 beta 4 is another receptor for Laminin-10/11. Even with lung carcinoma cells, the alpha 6-containing integrins partly contributed to adhesion to Laminin-10/11 at higher coating concentrations, although non-integrin receptor(s) might also be involved under such conditions. These results indicated that Laminin-10/11 are potent and versatile adhesive ligands in basement membranes capable of binding to both alpha 3 beta 1 and alpha 6 beta 1 integrins with high avidity and also to alpha 6 beta 4 integrin.
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integrin binding specificity of Laminin 10 11 Laminin 10 11 are recognized by α3β1 α6β1 and α6β4 integrins
2000Co-Authors: Yamato Kikkawa, Noriko Sanzen, Hironobu Fujiwara, Arnoud Sonnenberg, Kiyotoshi SekiguchiAbstract:Laminin-10/11, the Laminin isoforms containing the α5 chain, are major components of basement membranes of many fetal and adult tissues. Laminin-10/11 purified from the conditioned medium of human lung carcinoma cells were potent in mediating adhesion of the carcinoma cells in an integrin α3β1-dependent manner. To further define the type(s) of integrins involved in cell adhesion to Laminin10/11, we examined the effects of a panel of functionblocking anti-integrin antibodies on the adhesion of different cell types to Laminin-10/11. Although anti-integrin β1 antibody inhibited the adhesion of all cell types tested, anti-α3 antibody inhibited the adhesion of carcinoma and glioma cells but not fibroblastic cells. Adhesion of fibroblastic cells was inhibited, however, by a combination of anti-α3 and anti-α6 antibodies, suggesting that both α3β1 and α6β1 integrins function as Laminin-10/11 receptors in these cells. To explore this possibility, we examined the adhesion of K562 leukemic cells transfected with integrin α3 or α6 subunit to Laminin-10/11 or other Laminin isoforms. Laminin-10/11 were potent adhesive ligands for both the α3β1 and α6β1 transfectants, whereas Laminin-5 was the preferred ligand for the α3β1 transfectants. Upon stimulation with the activating antiintegrin β1 antibody, both transfectants became more adherent to the substratum regardless of the type of Laminins coated, although their preference for Laminin isoforms remained unaltered. K562 cells transfected with α6 and β4 subunits were also capable of adhering to Laminin-10/11, indicating that integrin α6β4 is another receptor for Laminin-10/11. Even with lung carcinoma cells, the α6-containing integrins partly contributed to adhesion to Laminin-10/11 at higher coating concentrations, although non-integrin receptor(s) might also be involved under such conditions. These results indicated that Laminin-10/11 are potent and versatile adhesive ligands in basement membranes capable of binding to both α3β1 and α6β1 integrins with high avidity and also to α6β4 integrin. SUMMARY
