Abstract
The signal transducer and activator of transcription (STAT)1 is a cytoplasmic-transcription factor that is phosphorylated by Janus kinases (Jak) in response to interferon gamma(IFN-gamma). The phosphorylated STAT1 translocates to the nucleus, where it turns on specific sets of IFN-gamma-inducible genes, such as the interferon regulatory factor (IRF)-1. We show here that gamma irradiation reduces the IFN-gamma mRNA expression. The inhibition of the STAT1 phosphorylation and the IRF-1 expression by gamma irradiation was also observed. In contrast, the mRNA levels of IL-5 and transcription factor GATA-3 were slightly induced by gamma irradiation when compared to the non-irradiated sample. Furthermore, we detected the inhibition of cell-mediated immunity by gamma irradiation in the allogenic-mixed lymphocytes' reaction (MLR). These results postulate that gamma irradiation induces the polarized-Th2 response and interferes with STAT1 signals, thereby causing the immunosuppression of the Th1 response.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus
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Animals
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Cell Nucleus / metabolism
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Cell Survival
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Cells, Cultured
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DNA-Binding Proteins / biosynthesis*
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DNA-Binding Proteins / metabolism
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Dose-Response Relationship, Radiation
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Down-Regulation
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GATA3 Transcription Factor
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Gamma Rays*
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Interferon Regulatory Factor-1
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Interferon-gamma / biosynthesis*
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Interleukin-5 / metabolism
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Lymphocytes / metabolism*
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Mice
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Mice, Inbred BALB C
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Phosphoproteins / metabolism
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Phosphorylation
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RNA, Messenger / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
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STAT1 Transcription Factor
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Spleen / cytology
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Spleen / radiation effects*
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Th1 Cells
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Trans-Activators / biosynthesis*
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Trans-Activators / metabolism
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Transcription, Genetic
Substances
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DNA-Binding Proteins
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GATA3 Transcription Factor
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Gata3 protein, mouse
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Interferon Regulatory Factor-1
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Interleukin-5
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Irf1 protein, mouse
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Phosphoproteins
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RNA, Messenger
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STAT1 Transcription Factor
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Stat1 protein, mouse
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Trans-Activators
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Interferon-gamma