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Brunner MC, Chambers CA, Chan FKM, Hanke J, Winoto A, Allison JP. CTLA-4-Mediated Inhibition of Early Events of T Cell Proliferation. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.10.5813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
CTLA-4 engagement by mAbs inhibits, while CD28 enhances, IL-2 production and proliferation upon T cell activation. Here, we have analyzed the mechanisms involved in CTLA-4-mediated inhibition of T cell activation of naive CD4+ T cells using Ab cross-linking. CTLA-4 ligation inhibited CD3/CD28-induced IL-2 mRNA accumulation by inhibiting IL-2 transcription, which appears to be mediated in part through decreasing NF-AT accumulation in the nuclei. However, CTLA-4 ligation did not appear to affect the CD28-mediated stabilization of IL-2 mRNA. Further, CTLA-4 engagement inhibited progression through the cell cycle by inhibiting the production of cyclin D3, cyclin-dependent kinase (cdk)4, and cdk6 when the T cells were stimulated with anti-CD3/CD28 and with anti-CD3 alone. These results indicate that CTLA-4 signaling inhibits events early in T cell activation both at IL-2 transcription and at the level of IL-2-independent events of the cell cycle, and does not simply oppose CD28-mediated costimulation.
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Affiliation(s)
- Monika C. Brunner
- *Howard Hughes Medical Research Institute, Cancer Research Laboratory, Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720; and
| | - Cynthia A. Chambers
- *Howard Hughes Medical Research Institute, Cancer Research Laboratory, Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720; and
| | - Francis Ka-Ming Chan
- *Howard Hughes Medical Research Institute, Cancer Research Laboratory, Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720; and
| | - Jeff Hanke
- †Central Division, Pfizer Inc., Groton, CT 06340
| | - Astar Winoto
- *Howard Hughes Medical Research Institute, Cancer Research Laboratory, Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720; and
| | - James P. Allison
- *Howard Hughes Medical Research Institute, Cancer Research Laboratory, Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720; and
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Cron RQ, Bort SJ, Wang Y, Brunvand MW, Lewis DB. T Cell Priming Enhances IL-4 Gene Expression by Increasing Nuclear Factor of Activated T Cells. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.2.860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The repetitive activation of T cells (priming) enhances the expression of many cytokines, such as IL-4, but not others, such as IL-2. Molecular mechanisms underlying selective expression of cytokines by T cells remain poorly understood. Here we show that priming of CD4 T cells selectively enhances IL-4 expression relative to IL-2 expression by a transcriptional mechanism involving nuclear factor of activated T cells (NFAT) proteins. As detected by in vivo footprinting, priming markedly increases the activation-dependent engagement of the P0 and P1 NFAT-binding elements of the IL-4 promoter. Moreover, each proximal P element is essential for optimal IL-4 promoter activity. Activated primed CD4 T cells contain more NFAT1 and support greater NFAT-directed transcription than unprimed CD4 T cells, while activator protein 1 binding and activator protein 1-mediated transcription by both cell types is similar. Increased expression of wild-type NFAT1 substantially increases IL-4 promoter activity in unprimed CD4 T cells, suggesting NFAT1 may be limiting for IL-4 gene expression in this cell type. Furthermore, a truncated form of NFAT1 acts as a dominant-negative, reducing IL-4 promoter activity in primed CD4 T cells and confirming the importance of endogenous NFAT to increased IL-4 gene expression by effector T cells. NFAT1 appears to be the major NFAT family member responsible for the initial increased expression of IL-4 by primed CD4 T cells.
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Affiliation(s)
- Randy Q. Cron
- *Departments of Pediatrics and Immunology, University of Washington, Seattle, WA 98195; and
| | - Susan J. Bort
- *Departments of Pediatrics and Immunology, University of Washington, Seattle, WA 98195; and
| | - Yunxia Wang
- *Departments of Pediatrics and Immunology, University of Washington, Seattle, WA 98195; and
| | - Mark W. Brunvand
- †Department of Internal Medicine, Oregon Health Sciences University, Portland, OR 97201
| | - David B. Lewis
- *Departments of Pediatrics and Immunology, University of Washington, Seattle, WA 98195; and
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