The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Steven D. Rosen - One of the best experts on this subject based on the ideXlab platform.
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Rapid Publication A Lymphocyte Homing Receptor (L-Selectin) Mediates the In Vitro Attachment of Lymphocytes to Myelinated Tracts of the Central Nervous System
2016Co-Authors: Kun Huang, Mark S. Singer, J S Geoffroy, Steven D. RosenAbstract:Lymphocytes enter lymph nodes by first adhering to high endo-thelial venules, an adhesive event mediated by a lectinlike lym-phocyte Receptor (L-selectin). Previously, it was shown with an in vitro assay that Lymphocytes preferentially adhere to myelin-rich regions in brain sections. Here, using a recombinant form of L-selectin as an immunohistochemical reagent, we demon-strate potential ligands for L-selectin in myelinated regions of the central but not the peripheral nervous system. Using sev-eral antibodies and phorbol ester downmodulation of the recep-tor, we establish that L-selectin on human Lymphocytes has a primary involvement in Lymphocyte adherence to the myelin-ated regions. On mouse Lymphocytes, the contribution of L-selectin appears to be partial. These findings raise the possibil-ity that leukocyte targeting to myelin-rich regions, via a L-selectin dependent mechanism, may be a factor in the patho-genesis of certain central nervous system demyelinating dis
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a Lymphocyte Homing Receptor l selectin mediates the in vitro attachment of Lymphocytes to myelinated tracts of the central nervous system
Journal of Clinical Investigation, 1991Co-Authors: Kun Huang, J S Geoffroy, M S Singer, Steven D. RosenAbstract:Lymphocytes enter lymph nodes by first adhering to high endothelial venules, an adhesive event mediated by a lectinlike Lymphocyte Receptor (L-selectin). Previously, it was shown with an in vitro assay that Lymphocytes preferentially adhere to myelin-rich regions in brain sections. Here, using a recombinant form of L-selectin as an immunohistochemical reagent, we demonstrate potential ligands for L-selectin in myelinated regions of the central but not the peripheral nervous system. Using several antibodies and phorbol ester downmodulation of the Receptor, we establish that L-selectin on human Lymphocytes has a primary involvement in Lymphocyte adherence to the myelinated regions. On mouse Lymphocytes, the contribution of L-selectin appears to be partial. These findings raise the possibility that leukocyte targeting to myelin-rich regions, via a L-selectin dependent mechanism, may be a factor in the pathogenesis of certain central nervous system demyelinating diseases.
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Identification of a carbohydrate-based endothelial ligand for a Lymphocyte Homing Receptor
The Journal of cell biology, 1991Co-Authors: Yasuyuki Imai, Laurence A. Lasky, Christopher Fennie, Mark S. Singer, Steven D. RosenAbstract:Lymphocyte attachment to high endothelial venules within lymph nodes is mediated by the peripheral lymph node Homing Receptor (pnHR), originally defined on mouse Lymphocytes by the MEL-14 mAb. The pnHR is a calcium-dependent lectin-like Receptor, a member of the LEC-CAM family of adhesion proteins. Here, using a soluble recombinant form of the Homing Receptor, we have identified an endothelial ligand for the pnHR as an approximately 50-kD sulfated, fucosylated, and sialylated glycoprotein, which we designate Sgp50 (sulfated glycoprotein of 50 kD). Recombinant Receptor binding to this lymph node-specific glycoprotein requires calcium and is inhibitable by specific carbohydrates and by MEL-14 mAb. Sialylation of the component is required for binding. Additionally, the glycoprotein is precipitated by MECA-79, an adhesion-blocking mAb reactive with lymph node HEV. A related glycoprotein of approximately 90 kD (designated as Sgp90) is also identified.
David G Jackson - One of the best experts on this subject based on the ideXlab platform.
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proteoglycan forms of the Lymphocyte Homing Receptor cd44 are alternatively spliced variants containing the v3 exon
Journal of Cell Biology, 1995Co-Authors: David G Jackson, John I Bell, R Dickinson, J Timans, J Shields, N WhittleAbstract:The CD44 cell surface glycoprotein is expressed on a broad range of different tissues as multiple isoforms containing from one to ten alternatively spliced exons v1-v10 inserted within the extracellular domain. Differential glycosylation generates still further variability, yielding both N- and O-glycan-modified forms of CD44 in addition to proteoglycan-like variants containing chondroitin sulphate and heparan sulphate. These high molecular mass proteoglycan-like variants, previously identified in Lymphocytes, melanomas, and keratinocytes have been implicated in cell-matrix adhesion, cell motility, and invasiveness. More recently, monocyte CD44 molecules presumed to carry glycosaminoglycan chains were shown to bind the chemokine MIP-1 beta (Tanaka, Y.,D. H. Adams, S. Hubscher, H. Hirano, U. Siebenlist, and S. Shaw. 1993. Nature (Lond). 361:79-82.) raising the intriguing possibility that proteoglycan-like CD44 variants might play a role in regulating inflammatory responses. Here we have investigated the molecular identity of these proteoglycan-like CD44 variants by generating a panel of recombinant CD44 isoforms using a novel cassette cloning strategy. We show that both chondroitin and heparan sulphate modifications are associated specifically with isoforms (CD44v3-10 and CD44v3,8-10) containing the v3 alternative exon which encodes a consensus motif SGXG for GAG addition. Other isoforms (CD44v10, CD44v8-10, CD44v7-10, and CD44v6-10) are shown to lack these GAG chains but to carry extensive O-glycan modifications, most likely within the mucin-like alternative exon inserts. We also demonstrate that the majority of endogenous GAG-modified CD44 isoforms present in epithelial cells constitute v3 isoforms thus establishing that in these cells the majority of proteoglycan-like CD44 variants are generated by alternative splicing. Finally we present evidence using transfected B lymphoma cells that the GAG-modified CD44 isoforms CD44v3-10 and CD44v3,8-10, unlike CD44H, bind only weakly to hyaluronan. Together with the demonstration in the accompanying paper (Bennett, K., D. G. Jackson, J.C. Simon, E. Tanczos, R. Peach, B. Modrell, I. Stamenkovic, G. Plowman, and A. Aruffo. 1995. J. Cell Biol. 128:687-698.), that CD44 molecules containing the v3 exon bind growth factors, these results highlight a new and potentially important role for CD44 alternative splicing in the control of cell-surface proteoglycan expression.
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genomic structure of dna encoding the Lymphocyte Homing Receptor cd44 reveals at least 12 alternatively spliced exons
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: Gavin Screaton, David G Jackson, Martyn V Bell, Francois Cornelis, Ulrich Gerth, John L BellAbstract:Abstract The CD44 molecule is known to display extensive size heterogeneity, which has been attributed both to alternative splicing and to differential glycosylation within the extracellular domain. Although the presence of several alternative exons has been partly inferred from cDNA sequencing, the precise intron-exon organization of the CD44 gene has not been described to date to our knowledge. In the present study we describe the structure of the human CD44 gene, which contains at least 19 exons spanning some 50 kilobases of DNA. We have identified 10 alternatively spliced exons within the extracellular domain, including 1 exon that has not been previously reported. In addition to the inclusion or exclusion of whole exons, more diversity is generated through the utilization of internal splice donor and acceptor sites within 2 of the individual exons. The variation previously reported for the cytoplasmic domain is shown to result from the alternative splicing of 2 exons. The genomic structure of CD44 reveals a remarkable degree of complexity, and we confirm the role of alternative splicing as the basis of the structural and functional diversity seen in the CD44 molecule.
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multiple variants of the human Lymphocyte Homing Receptor cd44 generated by insertions at a single site in the extracellular domain
Journal of Biological Chemistry, 1992Co-Authors: David G Jackson, J Buckley, John I BellAbstract:The human CD44 cell-surface glycoprotein participates in a wide variety of cell-cell interactions including Lymphocyte Homing and tumor metastasis. The CD44 antigen is known to display extensive size heterogeneity when compared between different tissue sources although the structural basis for this variation is not yet clear. Recently, two further isotypes in addition to the basic hemopoietic form of the CD44 antigen have been cloned and sequenced and these have been found to contain all or part of a 200-400-base pair insert within the extracellular domain, suggesting that the characteristic heterogeneity in the molecule may be generated by a mechanism of alternative splicing. We have obtained further evidence for alternative splicing, and we report here the cloning and sequencing of six different CD44 sequence variants from a variety of cell lines using a combination of expression cloning and the polymerase chain reaction. Comparison of these variants indicates that each is probably assembled by the insertion of five different exon units in tandem into a discrete site within the membrane proximal region of the extracellular domain. One of the variants contains an exon that shares extensive amino acid sequence homology with a recently described rat CD44 variant that mediates tumor metastasis. Another variant contains a new exon that encodes a tandem repeat of the consensus sequence SG for covalent modification with chondroitin sulfate and is expressed predominantly on mammary tumors. We suggest that a mechanism of alternative exon splicing generates much of the observed structural heterogeneity of CD44 and that the particular set of CD44 variants expressed in a single cell may represent a precise postal code directing the final destination of migrating cells and metastatic tumors.
Albert S B Edge - One of the best experts on this subject based on the ideXlab platform.
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species specific detection of porcine xenografts with an antibody against a novel epitope of the Lymphocyte Homing Receptor cd44
Xenotransplantation, 1997Co-Authors: Henry F Oettinger, Jennifer A Sullivan, Katherine E Crosby, Julie A Kelley, Douglas B Jaooby, Jonathan Dinsmore, Agatha Zawadzka, Albert S B EdgeAbstract:: We have isolated and characterized a murine monoclonal antibody, 10–14, that is reactive with an 85 kDa glycoprotein found on porcine peripheral blood Lymphocytes, cultured aortic endothelial cells, fetal cardiomyocytes, and mixed neural/glial cell cultures. In contrast to the anti-CD44 antibody Z062, which reacted with both porcine and murine CD44, the 10–14 antibody did not react with monkey, rabbit, rat, or murine cells, suggesting that 10–14 recognized a novel epitope found exclusively on the porcine CD44 molecule; 10–14 is thus a novel reagent for identification of xenotransplanted porcine cells. The reagent has been used in this study as an immunohistochemical probe to detect porcine neural cell grafts in the central nervous system of the rat and to label porcine fetal cardiomyocytes. Moreover, the antibody provides information on the expression of the CD44 molecule that is critical for Lymphocyte adhesion and trafficking.
John I Bell - One of the best experts on this subject based on the ideXlab platform.
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proteoglycan forms of the Lymphocyte Homing Receptor cd44 are alternatively spliced variants containing the v3 exon
Journal of Cell Biology, 1995Co-Authors: David G Jackson, John I Bell, R Dickinson, J Timans, J Shields, N WhittleAbstract:The CD44 cell surface glycoprotein is expressed on a broad range of different tissues as multiple isoforms containing from one to ten alternatively spliced exons v1-v10 inserted within the extracellular domain. Differential glycosylation generates still further variability, yielding both N- and O-glycan-modified forms of CD44 in addition to proteoglycan-like variants containing chondroitin sulphate and heparan sulphate. These high molecular mass proteoglycan-like variants, previously identified in Lymphocytes, melanomas, and keratinocytes have been implicated in cell-matrix adhesion, cell motility, and invasiveness. More recently, monocyte CD44 molecules presumed to carry glycosaminoglycan chains were shown to bind the chemokine MIP-1 beta (Tanaka, Y.,D. H. Adams, S. Hubscher, H. Hirano, U. Siebenlist, and S. Shaw. 1993. Nature (Lond). 361:79-82.) raising the intriguing possibility that proteoglycan-like CD44 variants might play a role in regulating inflammatory responses. Here we have investigated the molecular identity of these proteoglycan-like CD44 variants by generating a panel of recombinant CD44 isoforms using a novel cassette cloning strategy. We show that both chondroitin and heparan sulphate modifications are associated specifically with isoforms (CD44v3-10 and CD44v3,8-10) containing the v3 alternative exon which encodes a consensus motif SGXG for GAG addition. Other isoforms (CD44v10, CD44v8-10, CD44v7-10, and CD44v6-10) are shown to lack these GAG chains but to carry extensive O-glycan modifications, most likely within the mucin-like alternative exon inserts. We also demonstrate that the majority of endogenous GAG-modified CD44 isoforms present in epithelial cells constitute v3 isoforms thus establishing that in these cells the majority of proteoglycan-like CD44 variants are generated by alternative splicing. Finally we present evidence using transfected B lymphoma cells that the GAG-modified CD44 isoforms CD44v3-10 and CD44v3,8-10, unlike CD44H, bind only weakly to hyaluronan. Together with the demonstration in the accompanying paper (Bennett, K., D. G. Jackson, J.C. Simon, E. Tanczos, R. Peach, B. Modrell, I. Stamenkovic, G. Plowman, and A. Aruffo. 1995. J. Cell Biol. 128:687-698.), that CD44 molecules containing the v3 exon bind growth factors, these results highlight a new and potentially important role for CD44 alternative splicing in the control of cell-surface proteoglycan expression.
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multiple variants of the human Lymphocyte Homing Receptor cd44 generated by insertions at a single site in the extracellular domain
Journal of Biological Chemistry, 1992Co-Authors: David G Jackson, J Buckley, John I BellAbstract:The human CD44 cell-surface glycoprotein participates in a wide variety of cell-cell interactions including Lymphocyte Homing and tumor metastasis. The CD44 antigen is known to display extensive size heterogeneity when compared between different tissue sources although the structural basis for this variation is not yet clear. Recently, two further isotypes in addition to the basic hemopoietic form of the CD44 antigen have been cloned and sequenced and these have been found to contain all or part of a 200-400-base pair insert within the extracellular domain, suggesting that the characteristic heterogeneity in the molecule may be generated by a mechanism of alternative splicing. We have obtained further evidence for alternative splicing, and we report here the cloning and sequencing of six different CD44 sequence variants from a variety of cell lines using a combination of expression cloning and the polymerase chain reaction. Comparison of these variants indicates that each is probably assembled by the insertion of five different exon units in tandem into a discrete site within the membrane proximal region of the extracellular domain. One of the variants contains an exon that shares extensive amino acid sequence homology with a recently described rat CD44 variant that mediates tumor metastasis. Another variant contains a new exon that encodes a tandem repeat of the consensus sequence SG for covalent modification with chondroitin sulfate and is expressed predominantly on mammary tumors. We suggest that a mechanism of alternative exon splicing generates much of the observed structural heterogeneity of CD44 and that the particular set of CD44 variants expressed in a single cell may represent a precise postal code directing the final destination of migrating cells and metastatic tumors.
N Whittle - One of the best experts on this subject based on the ideXlab platform.
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proteoglycan forms of the Lymphocyte Homing Receptor cd44 are alternatively spliced variants containing the v3 exon
Journal of Cell Biology, 1995Co-Authors: David G Jackson, John I Bell, R Dickinson, J Timans, J Shields, N WhittleAbstract:The CD44 cell surface glycoprotein is expressed on a broad range of different tissues as multiple isoforms containing from one to ten alternatively spliced exons v1-v10 inserted within the extracellular domain. Differential glycosylation generates still further variability, yielding both N- and O-glycan-modified forms of CD44 in addition to proteoglycan-like variants containing chondroitin sulphate and heparan sulphate. These high molecular mass proteoglycan-like variants, previously identified in Lymphocytes, melanomas, and keratinocytes have been implicated in cell-matrix adhesion, cell motility, and invasiveness. More recently, monocyte CD44 molecules presumed to carry glycosaminoglycan chains were shown to bind the chemokine MIP-1 beta (Tanaka, Y.,D. H. Adams, S. Hubscher, H. Hirano, U. Siebenlist, and S. Shaw. 1993. Nature (Lond). 361:79-82.) raising the intriguing possibility that proteoglycan-like CD44 variants might play a role in regulating inflammatory responses. Here we have investigated the molecular identity of these proteoglycan-like CD44 variants by generating a panel of recombinant CD44 isoforms using a novel cassette cloning strategy. We show that both chondroitin and heparan sulphate modifications are associated specifically with isoforms (CD44v3-10 and CD44v3,8-10) containing the v3 alternative exon which encodes a consensus motif SGXG for GAG addition. Other isoforms (CD44v10, CD44v8-10, CD44v7-10, and CD44v6-10) are shown to lack these GAG chains but to carry extensive O-glycan modifications, most likely within the mucin-like alternative exon inserts. We also demonstrate that the majority of endogenous GAG-modified CD44 isoforms present in epithelial cells constitute v3 isoforms thus establishing that in these cells the majority of proteoglycan-like CD44 variants are generated by alternative splicing. Finally we present evidence using transfected B lymphoma cells that the GAG-modified CD44 isoforms CD44v3-10 and CD44v3,8-10, unlike CD44H, bind only weakly to hyaluronan. Together with the demonstration in the accompanying paper (Bennett, K., D. G. Jackson, J.C. Simon, E. Tanczos, R. Peach, B. Modrell, I. Stamenkovic, G. Plowman, and A. Aruffo. 1995. J. Cell Biol. 128:687-698.), that CD44 molecules containing the v3 exon bind growth factors, these results highlight a new and potentially important role for CD44 alternative splicing in the control of cell-surface proteoglycan expression.
