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Matrix valency regulates integrin-mediated lymphoid adhesion via Syk kinase.

Stupack DG, Li E, Silletti SA, Kehler JA, Geahlen RL, Hahn K, Nemerow GR, Cheresh DA - J. Cell Biol. (1999)

Bottom Line: Nonactivated lymphoid cells attach preferentially to polymerized ECM proteins yet are unable to attach to monomeric forms or fragments of these proteins without previous activation.Adhesion of nonactivated lymphoid cells to polymeric ECM components results in activation of the antigen receptor-associated Syk kinase that accumulates in adhesion-promoting podosomes.In fact, activation of Syk by antigen or agonists, as well as expression of an activated Syk mutant in lymphoid cells, facilitates their adhesion to monomeric ECM proteins or their fragments.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.

ABSTRACT
Lymphocytes accumulate within the extracellular matrix (ECM) of tumor, wound, or inflammatory tissues. These tissues are largely comprised of polymerized adhesion proteins such as fibrin and fibronectin or their fragments. Nonactivated lymphoid cells attach preferentially to polymerized ECM proteins yet are unable to attach to monomeric forms or fragments of these proteins without previous activation. This adhesion event depends on the appropriate spacing of integrin adhesion sites. Adhesion of nonactivated lymphoid cells to polymeric ECM components results in activation of the antigen receptor-associated Syk kinase that accumulates in adhesion-promoting podosomes. In fact, activation of Syk by antigen or agonists, as well as expression of an activated Syk mutant in lymphoid cells, facilitates their adhesion to monomeric ECM proteins or their fragments. These results reveal a cooperative interaction between signals emanating from integrins and antigen receptors that can serve to regulate stable lymphoid cell adhesion and retention within a remodeling ECM.

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Confocal immunofluorescent microscopic  examination of Syk localization during LCL attachment.  LCL were allowed to attach  for 10 (A and B) or 30 (C)  min and subsequently fixed  and stained for the presence  of endogenous Syk with  monoclonal 4D10 followed  by secondary detection by  FITC-conjugated goat anti– mouse (green), and costained with rhodamine-conjugated phalloidin to label  F-actin (red). Significant  colocalization of the signals  (yellow) did not occur in  nonadherent LCL (A, arrow) and was modest in confocal Z sections of adherent  LCL viewed above the adhesive substrate (A) (Z  plane = 11 μm above the  substrate). Colocalization of  signal was observed consistently in the podosomes (B,  arrows) of actively attaching  LCL at the cell–substratum  interface (Z plane = 1 μm above the substrate), but not in fully  spread cells at 30 min (C) (Z plane = 1 μm above the substrate).  All Z sections are 1 μm. Bar, 10 μm.
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Figure 8: Confocal immunofluorescent microscopic examination of Syk localization during LCL attachment. LCL were allowed to attach for 10 (A and B) or 30 (C) min and subsequently fixed and stained for the presence of endogenous Syk with monoclonal 4D10 followed by secondary detection by FITC-conjugated goat anti– mouse (green), and costained with rhodamine-conjugated phalloidin to label F-actin (red). Significant colocalization of the signals (yellow) did not occur in nonadherent LCL (A, arrow) and was modest in confocal Z sections of adherent LCL viewed above the adhesive substrate (A) (Z plane = 11 μm above the substrate). Colocalization of signal was observed consistently in the podosomes (B, arrows) of actively attaching LCL at the cell–substratum interface (Z plane = 1 μm above the substrate), but not in fully spread cells at 30 min (C) (Z plane = 1 μm above the substrate). All Z sections are 1 μm. Bar, 10 μm.

Mentions: Surprisingly, if LCL were allowed to attach and spread, no reversal of adhesion was observed after the addition of piceatannol (data not shown), suggesting that activation of Syk was important in the initial phase of adhesion of lymphoid cells to the multimeric ligands. Therefore, Syk localization was examined by immunofluorescent confocal microscopy during attachment. In nonadherent LCL cells Syk is present diffusely in the cytosol and does not significantly colocalize with actin in the microspikes present ubiquitously across the cell surface (Fig. 8 A, arrow). Similarly, there is only modest colocalization of Syk and actin in adherent cells above the plane of interaction with substrate (Fig. 8 A, +10-μm Z section). However, we consistently observed colocalization of Syk and actin in the podosome near the cell–substrate interface during early phases of cell attachment (Fig. 8 B), although this colocalization disappeared upon full cell spreading (Fig. 8 C). Together, these results suggest that the activation of Syk plays a role in the initial polarization of cells leading to productive attachment on multimeric ligand.


Matrix valency regulates integrin-mediated lymphoid adhesion via Syk kinase.

Stupack DG, Li E, Silletti SA, Kehler JA, Geahlen RL, Hahn K, Nemerow GR, Cheresh DA - J. Cell Biol. (1999)

Confocal immunofluorescent microscopic  examination of Syk localization during LCL attachment.  LCL were allowed to attach  for 10 (A and B) or 30 (C)  min and subsequently fixed  and stained for the presence  of endogenous Syk with  monoclonal 4D10 followed  by secondary detection by  FITC-conjugated goat anti– mouse (green), and costained with rhodamine-conjugated phalloidin to label  F-actin (red). Significant  colocalization of the signals  (yellow) did not occur in  nonadherent LCL (A, arrow) and was modest in confocal Z sections of adherent  LCL viewed above the adhesive substrate (A) (Z  plane = 11 μm above the  substrate). Colocalization of  signal was observed consistently in the podosomes (B,  arrows) of actively attaching  LCL at the cell–substratum  interface (Z plane = 1 μm above the substrate), but not in fully  spread cells at 30 min (C) (Z plane = 1 μm above the substrate).  All Z sections are 1 μm. Bar, 10 μm.
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Figure 8: Confocal immunofluorescent microscopic examination of Syk localization during LCL attachment. LCL were allowed to attach for 10 (A and B) or 30 (C) min and subsequently fixed and stained for the presence of endogenous Syk with monoclonal 4D10 followed by secondary detection by FITC-conjugated goat anti– mouse (green), and costained with rhodamine-conjugated phalloidin to label F-actin (red). Significant colocalization of the signals (yellow) did not occur in nonadherent LCL (A, arrow) and was modest in confocal Z sections of adherent LCL viewed above the adhesive substrate (A) (Z plane = 11 μm above the substrate). Colocalization of signal was observed consistently in the podosomes (B, arrows) of actively attaching LCL at the cell–substratum interface (Z plane = 1 μm above the substrate), but not in fully spread cells at 30 min (C) (Z plane = 1 μm above the substrate). All Z sections are 1 μm. Bar, 10 μm.
Mentions: Surprisingly, if LCL were allowed to attach and spread, no reversal of adhesion was observed after the addition of piceatannol (data not shown), suggesting that activation of Syk was important in the initial phase of adhesion of lymphoid cells to the multimeric ligands. Therefore, Syk localization was examined by immunofluorescent confocal microscopy during attachment. In nonadherent LCL cells Syk is present diffusely in the cytosol and does not significantly colocalize with actin in the microspikes present ubiquitously across the cell surface (Fig. 8 A, arrow). Similarly, there is only modest colocalization of Syk and actin in adherent cells above the plane of interaction with substrate (Fig. 8 A, +10-μm Z section). However, we consistently observed colocalization of Syk and actin in the podosome near the cell–substrate interface during early phases of cell attachment (Fig. 8 B), although this colocalization disappeared upon full cell spreading (Fig. 8 C). Together, these results suggest that the activation of Syk plays a role in the initial polarization of cells leading to productive attachment on multimeric ligand.

Bottom Line: Nonactivated lymphoid cells attach preferentially to polymerized ECM proteins yet are unable to attach to monomeric forms or fragments of these proteins without previous activation.Adhesion of nonactivated lymphoid cells to polymeric ECM components results in activation of the antigen receptor-associated Syk kinase that accumulates in adhesion-promoting podosomes.In fact, activation of Syk by antigen or agonists, as well as expression of an activated Syk mutant in lymphoid cells, facilitates their adhesion to monomeric ECM proteins or their fragments.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.

ABSTRACT
Lymphocytes accumulate within the extracellular matrix (ECM) of tumor, wound, or inflammatory tissues. These tissues are largely comprised of polymerized adhesion proteins such as fibrin and fibronectin or their fragments. Nonactivated lymphoid cells attach preferentially to polymerized ECM proteins yet are unable to attach to monomeric forms or fragments of these proteins without previous activation. This adhesion event depends on the appropriate spacing of integrin adhesion sites. Adhesion of nonactivated lymphoid cells to polymeric ECM components results in activation of the antigen receptor-associated Syk kinase that accumulates in adhesion-promoting podosomes. In fact, activation of Syk by antigen or agonists, as well as expression of an activated Syk mutant in lymphoid cells, facilitates their adhesion to monomeric ECM proteins or their fragments. These results reveal a cooperative interaction between signals emanating from integrins and antigen receptors that can serve to regulate stable lymphoid cell adhesion and retention within a remodeling ECM.

Show MeSH
Related in: MedlinePlus