Cas-L is required for beta 1 integrin-mediated costimulation in human Tcells.
Beta 1 integrins provide a costimulus for TCR/CD3-driven T cell activation and IL-2 production in human peripheral T cells. However, this beta 1 integrin-mediated costimulation is impaired in a human T lymphoblastic line, Jurkat. We studied the molecular basis of this impaired costimulation and found that Cas-L, a 105-kDa docking protein, is marginally expressed in Jurkat T cells, whereas Cas-L is well expressed in peripheral T cells. Cas-L is a binding protein and a substrate for focal adhesion kinase and is tyrosine phosphorylated by beta 1 integrin stimulation. We here show that the transfection of wild-type Cas-L in Jurkat T cells restores beta 1 integrin-mediated costimulation. However, Cas-L transfection had no effect on CD28-mediated costimulation, indicating that Cas-L is specifically involved in the beta 1 integrin-mediated signaling pathway. Furthermore, transfection of the Cas-L Delta SH3 mutant failed to restore beta 1 integrin-mediated costimulation in Jurkat cells. Cas-L Delta SH3 mutant lacks the binding site for focal adhesion kinase and is not tyrosine phosphorylated after beta 1 integrin stimulation. These findings strongly suggest that the tyrosine phosphorylation of Cas-L plays a key role in the signal transduction in the beta 1 integrin-mediated T cell costimulation.
Division of Tumor Immunology, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
K
K
Kamiguchi
K
K
Tachibana
S
S
Iwata
Y
Y
Ohashi
C
C
Morimoto
D048868:Adaptor Proteins, Signal Transducing; D000276:Adjuvants, Immunologic / Q000502:physiology; D001665:Binding Sites / Q000235:genetics; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D005353:Fibronectins / Q000235:genetics / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D019012:Integrin beta1 / Q000502:physiology*; D007376:Interleukin-2 / Q000096:biosynthesis / Q000097:blood; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000235:genetics; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic; D014162:Transfection / Q000276:immunology; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D000276:Adjuvants, Immunologic; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D019012:Integrin beta1; D007376:Interleukin-2; C099942:NEDD9 protein, human; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human