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Won J, Hur YG, Hur EM, Park SH, Kang MA, Choi Y, Park C, Lee KH, Yun Y. Rosmarinic acid inhibits TCR-induced T cell activation and proliferation in an Lck-dependent manner. Eur J Immunol 2003; 33:870-9. [PMID: 12672052 DOI: 10.1002/eji.200323010] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Lck is a T cell-restricted Src family protein tyrosine kinase that plays pivotal roles in TCR-mediated signaling. We aimed to identify novel agents that could disrupt the molecular interaction of the Src homology 2-domain of Lck (Lck SH2) with its binding partners, with the expectation that this would impair TCR signaling and generate immunosuppression. Large-scale screening of plant extracts indicated that rosmarinic acid (RosA) in extracts of Prunella vulgaris consistently inhibits the interaction between Lck SH2 and a peptide containing its consensus binding sequence (pYEEI). The inhibitory effect of RosA was specific for SH2 domains of Src family protein tyrosine kinase. RosA inhibited TCR-induced-Ca(2+) mobilization and IL-2 promoter activation but not phorbol 12-myristate 13-acetate/ionomycin-induced IL-2 promoter activation, indicating its point of inhibition at the membrane proximal site of TCR signaling. Furthermore, RosA inhibited TCR-induced splenocyte proliferation as well as one-way MLR at an IC(50) of 25-50 microM and inhibited cytokine expression such as IL-2 and IFN-gamma. Here, we first report RosA as an inhibitor of TCR-signaling and subsequent T cell proliferation.
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Affiliation(s)
- Jonghwa Won
- Signal Transduction Laboratory, Mogam Biotechnology Research Institute, Yonginsi, Korea
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Choi YB, Kim CK, Yun Y. Lad, an Adapter Protein Interacting with the SH2 Domain of p56 lck, Is Required for T Cell Activation. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.10.5242] [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
T cell-specific Src family tyrosine kinase, p56lck, plays crucial roles in T cell differentiation, activation, and proliferation. These multiple functions of p56lck are believed to be conducted through the protein-protein interactions with various cellular signaling proteins. To clarify the mechanisms through which p56lck contributes to T cell signaling, we identified the proteins binding to the Src homology 2 (SH2) domain of p56lck through a tyrosine phosphorylation-dependent yeast two-hybrid screening. Subsequent characterization of positive clones revealed the presence of a protein of 366 aa named Lad (Lck-associated adapter protein), which is a potential murine homologue of previously reported TSAd, a T cell-specific adapter protein. Lad contains several protein-protein interaction domains including a zinc-finger motif, an SH2 domain, a proline-rich SH3 binding motif, and several phosphotyrosine sites. Furthermore, Lad was tyrosine phosphorylated and associated with p56lckin vivo and redistributed from cytoplasm to the plasma membrane in a T cell activation-dependent manner. Moreover in T cells, IL-2 promoter activity was enhanced upon coexpression of Lad but was inhibited by the coexpression of antisense Lad RNA. These characteristics of Lad suggest that Lad play an essential role as an adapter protein in p56lck-mediated T cell signaling.
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Affiliation(s)
- Young Bong Choi
- *Signal Transduction Laboratory Mogam Biotechnology Research Institute, Koosungmyon, Yonginsi, Kyunggido, Korea; and
- †Department of Molecular Life Science and Center for Cell Signaling Research, Ewha Women’s University, Seodaemungu, Daehyundong 11-1, Seoul, 120-750, Korea
| | - Chan Ki Kim
- *Signal Transduction Laboratory Mogam Biotechnology Research Institute, Koosungmyon, Yonginsi, Kyunggido, Korea; and
| | - Yungdae Yun
- *Signal Transduction Laboratory Mogam Biotechnology Research Institute, Koosungmyon, Yonginsi, Kyunggido, Korea; and
- †Department of Molecular Life Science and Center for Cell Signaling Research, Ewha Women’s University, Seodaemungu, Daehyundong 11-1, Seoul, 120-750, Korea
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