Anti-proliferative Activity of T-bet.
- Author:
Yeon Ji OH
1
;
Ji Hyun SHIN
;
Hee Yeon WON
;
Eun Sook HWANG
Author Information
- Publication Type:Original Article
- Keywords: T-bet; Proliferation; IFN-gamma; IL-2; Ecdysone; Th cells
- MeSH: Animals; Cell Proliferation; Ecdysone; Humans; Interleukin-2; Kidney; Mice; Th1 Cells; Transcription Factors
- From:Immune Network 2015;15(4):199-205
- CountryRepublic of Korea
- Language:English
- 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-gamma gene and activates its transcription, T-bet deficiency impairs IFN-gamma 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-gamma production and suppressed IL-2 expression. IFN-gamma 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-gamma-null mice to eliminate the anti-proliferative effect of IFN-gamma, 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-gamma 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-gamma- or an IL-2-independent manner.
