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KMID : 0923620150150040199
Immune Network
2015 Volume.15 No. 4 p.199 ~ p.205
Anti-proliferative Activity of T-bet
:Oh Yeon-Ji
:Shin Ji-Hyun/:Won Hee-Yeon/:Hwang Eun-Sook
Abstract
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-¥ã gene and activates its transcription, T-bet deficiency impairs IFN-¥ã 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-¥ã production and suppressed IL-2 expression. IFN-¥ã 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-¥ã-null mice to eliminate the anti-proliferative effect of IFN-¥ã, 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-¥ã 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-¥ã- or an IL-2-independent manner.
KEYWORD
T-bet, Proliferation, IFN-¥ã, IL-2, Ecdysone, Th cells
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