Limits...
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.

Show MeSH

Related in: MedlinePlus

Activation of Syk is associated with cellular adhesion.  (A) Antigen-activated murine γδ cytotoxic T cells were generated by coculture of splenic T cells from LCMV-challenged mice  with LCMV-infected helper cells. The γδ cells were tested for  their capacity to attach to monomeric or multimeric PB by adhesion assay. To confirm Syk activation, lysates derived from γδ  CTL plated on BSA (B), pentamer (PB5), or monomer (PB1) for  1 h were subjected to immunoprecipitation and Syk phosphorylation was assessed (inset). (B) Syk-deficient DT40 cells which  were reconstituted with cDNA constructs encoding either Syk  (WT) or a constitutively active form of Syk (Y130E), were determined to express similar levels of β1 integrin by flow cytometry  using the monoclonal antibody CSAT, which detects chick β1 integrin (inset). Cells were subsequently tested for their capacity to  attach to wells coated with varying concentrations of a monomeric fragment of fibronectin containing the Arg-Gly-Asp cell-binding domain.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2132930&req=5

Figure 9: Activation of Syk is associated with cellular adhesion. (A) Antigen-activated murine γδ cytotoxic T cells were generated by coculture of splenic T cells from LCMV-challenged mice with LCMV-infected helper cells. The γδ cells were tested for their capacity to attach to monomeric or multimeric PB by adhesion assay. To confirm Syk activation, lysates derived from γδ CTL plated on BSA (B), pentamer (PB5), or monomer (PB1) for 1 h were subjected to immunoprecipitation and Syk phosphorylation was assessed (inset). (B) Syk-deficient DT40 cells which were reconstituted with cDNA constructs encoding either Syk (WT) or a constitutively active form of Syk (Y130E), were determined to express similar levels of β1 integrin by flow cytometry using the monoclonal antibody CSAT, which detects chick β1 integrin (inset). Cells were subsequently tested for their capacity to attach to wells coated with varying concentrations of a monomeric fragment of fibronectin containing the Arg-Gly-Asp cell-binding domain.

Mentions: These results suggest that preactivation of Syk might be able to facilitate attachment to monomeric ligands. To determine whether nonintegrin mediated activation of Syk could regulate lymphoid adhesion, we examined an antigen-specific response in Syk-expressing, tissue-resident T cells. CTL cells specific for LCMV were established by coculture with LCMV-infected, irradiated helper cells, resulting in a proliferative response (Hahn et al., 1994) and the activation of Syk (Fig. 7 A, inset). In these CTL, Syk activation by antigen was sufficient to facilitate attachment to either monomeric or multimeric ligands (Fig. 9 A). To confirm that Syk activation was maintained in these cells, lysates from the CTL were generated and Syk immunoprecipitation and phosphotyrosine analysis performed at the conclusion of the adhesion assay. Interestingly, Syk phosphorylation was maintained in CTL populations plated on monomeric or multimeric substrate, but this was not the case when cells were plated on the nonadhesive substrate BSA (Fig. 9 A, inset). These results indicate that Syk phosphorylation may be maintained by ongoing adhesion, and that Syk activation correlates with stable adhesion to monomeric 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)

Activation of Syk is associated with cellular adhesion.  (A) Antigen-activated murine γδ cytotoxic T cells were generated by coculture of splenic T cells from LCMV-challenged mice  with LCMV-infected helper cells. The γδ cells were tested for  their capacity to attach to monomeric or multimeric PB by adhesion assay. To confirm Syk activation, lysates derived from γδ  CTL plated on BSA (B), pentamer (PB5), or monomer (PB1) for  1 h were subjected to immunoprecipitation and Syk phosphorylation was assessed (inset). (B) Syk-deficient DT40 cells which  were reconstituted with cDNA constructs encoding either Syk  (WT) or a constitutively active form of Syk (Y130E), were determined to express similar levels of β1 integrin by flow cytometry  using the monoclonal antibody CSAT, which detects chick β1 integrin (inset). Cells were subsequently tested for their capacity to  attach to wells coated with varying concentrations of a monomeric fragment of fibronectin containing the Arg-Gly-Asp cell-binding domain.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132930&req=5

Figure 9: Activation of Syk is associated with cellular adhesion. (A) Antigen-activated murine γδ cytotoxic T cells were generated by coculture of splenic T cells from LCMV-challenged mice with LCMV-infected helper cells. The γδ cells were tested for their capacity to attach to monomeric or multimeric PB by adhesion assay. To confirm Syk activation, lysates derived from γδ CTL plated on BSA (B), pentamer (PB5), or monomer (PB1) for 1 h were subjected to immunoprecipitation and Syk phosphorylation was assessed (inset). (B) Syk-deficient DT40 cells which were reconstituted with cDNA constructs encoding either Syk (WT) or a constitutively active form of Syk (Y130E), were determined to express similar levels of β1 integrin by flow cytometry using the monoclonal antibody CSAT, which detects chick β1 integrin (inset). Cells were subsequently tested for their capacity to attach to wells coated with varying concentrations of a monomeric fragment of fibronectin containing the Arg-Gly-Asp cell-binding domain.
Mentions: These results suggest that preactivation of Syk might be able to facilitate attachment to monomeric ligands. To determine whether nonintegrin mediated activation of Syk could regulate lymphoid adhesion, we examined an antigen-specific response in Syk-expressing, tissue-resident T cells. CTL cells specific for LCMV were established by coculture with LCMV-infected, irradiated helper cells, resulting in a proliferative response (Hahn et al., 1994) and the activation of Syk (Fig. 7 A, inset). In these CTL, Syk activation by antigen was sufficient to facilitate attachment to either monomeric or multimeric ligands (Fig. 9 A). To confirm that Syk activation was maintained in these cells, lysates from the CTL were generated and Syk immunoprecipitation and phosphotyrosine analysis performed at the conclusion of the adhesion assay. Interestingly, Syk phosphorylation was maintained in CTL populations plated on monomeric or multimeric substrate, but this was not the case when cells were plated on the nonadhesive substrate BSA (Fig. 9 A, inset). These results indicate that Syk phosphorylation may be maintained by ongoing adhesion, and that Syk activation correlates with stable adhesion to monomeric 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