Itk, a T cell-specific tyrosine kinase, is required for CD2-mediated interleukin-2 promoter activation in the human T cell line Jurkat.
We investigated the functional role of Itk, a member of the cytoplasmic tyrosine kinase Tec family, in T cell activation. Stimulation of either CD2 or T cell receptor (TCR)/CD3 on Tcells by monoclonal antibody-mediated cross-linking induced tyrosine phosphorylation of Itk, which was maximal as early as 1 min after stimulation. The tyrosine kinase activity in the anti-Itk immunoprecipitate was significantly activated upon these stimulations. Interleukin-2 (IL-2) promoter activity stimulated by cross-linking of CD2, TCR/CD3, and CD28 with antibodies was significantly reduced by transient expression of an Itk mutant lacking the kinase activity. The reduction paralleled a decrease in tyrosine phosphorylation of endogenous wild-type Itk. Stimulation of CD2 or TCR/CD3 induced activation of the nuclear factor of activated T cells (NFAT), the binding site of which is included in the IL-2 gene promoter. The activation of NFAT was also impaired by expression of the Itk mutant. These results demonstrate that Itk plays a role in IL-2 production, indicating a critical involvement of Itk in the initial stage of T cell activation by mediating signals from the TCR/CD3 complex, CD2, and CD28.
Tanaka
N
N
Department of Microbiology, Tohoku University School of Medicine, Sendai, Japan.
Abe
H
H
Yagita
H
H
Okumura
K
K
Nakamura
M
M
Sugamura
K
K
D018801:CD2 Antigens / Q000502:physiology*; D018106:CD28 Antigens / Q000502:physiology; D017252:CD3 Complex / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000235:genetics*; D019169:Jurkat Cells; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000276:immunology*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013379:Substrate Specificity / Q000276:immunology; D013601:T-Lymphocytes / Q000201:enzymology* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D018801:CD2 Antigens; D018106:CD28 Antigens; D017252:CD3 Complex; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011948:Receptors, Antigen, T-Cell; D014157:Transcription Factors; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C080813:emt protein-tyrosine kinase