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Anti-proliferative Activity of T-bet
T-bet is a critical transcription factor that regulates differentiation of Th1 cells from CD4(+) precursor cells. Since T-bet directly binds to the promoter of the IFN-γ gene and activates its transcription, T-bet deficiency impairs IFN-γ production in Th1 cells. Interestingly, T-bet-deficient Th ce...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Korean Association of Immunologists
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553258/ https://www.ncbi.nlm.nih.gov/pubmed/26330806 http://dx.doi.org/10.4110/in.2015.15.4.199 |
Sumario: | T-bet is a critical transcription factor that regulates differentiation of Th1 cells from CD4(+) precursor cells. Since T-bet directly binds to the promoter of the IFN-γ gene and activates its transcription, T-bet deficiency impairs IFN-γ production in Th1 cells. Interestingly, T-bet-deficient Th cells also display substantially augmented the production of IL-2, a T cell growth factor. Exogenous expression of T-bet in T-bet deficient Th cells rescued the IFN-γ production and suppressed IL-2 expression. IFN-γ and IL-2 reciprocally regulate Th cell proliferation following TCR stimulation. Therefore, we examined the effect of T-bet on Th cell proliferation and found that T-bet deficiency significantly enhanced Th cell proliferation under non-skewing, Th1-skewing, and Th2-skewing conditions. By using IFN-γ-null mice to eliminate the anti-proliferative effect of IFN-γ, T-bet deficiency still enhanced Th cell proliferation under both Th1- and Th2-skewing conditions. Since the anti-proliferative activity of T-bet may be influenced by IL-2 suppression in Th cells, we examined whether T-bet modulates IL-2-independent cell proliferation in a non-T cell population. We demonstrated that T-bet expression induced by ecdysone treatment in human embryonic kidney (HEK) cells increased IFN-γ promoter activity in a dose dependent manner, and sustained T-bet expression considerably decreased cell proliferation in HEK cells. Although the molecular mechanisms underlying anti-proliferative activity of T-bet remain to be elucidated, T-bet may directly suppress cell proliferation in an IFN-γ- or an IL-2-independent manner. |
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