IL-4 gene transcription in human T cells is suppressed by T-bet.
T-bet is crucially implicated in Th1 differentiation due to its strong promoting activity for IFN-gamma gene transcription. However, the regulatory role of T-bet in Th2 cytokines is not fully delineated.


METHODS
The effect of T-bet on mRNA expression as well as the promoter activity of IL-4 in human T cells was investigated by employing quantitative RT-PCR and fluorescence-based promoter reporter assay procedures.


RESULTS
IL-4 mRNA expression as well as the transcriptional activity of 5'-flanking region in the IL-4 gene encompassing -1105 to +4 in Jurkat cells was clearly upregulated upon stimulation. The inducible mRNA expression and the promoter activity of IL-4 were significantly diminished by ectopic expression of T-bet.


CONCLUSIONS
IL-4 gene transcription is inhibited by T-bet via the suppression of its promoter activity, independently of IFN-gamma. T-bet facilitates Th1 differentiation through not only upregulation of IFN-gamma, but also downregulation of IL-4 gene transcription.
Kitamura
Noriko
N
Cytokine Project, The Tokyo Metropolitan Institute of Medical Science, Bunkyo-ku, Tokyo, Japan.
Kitamura
Fujiko
F
Kaminuma
Osamu
O
Miyatake
Shoichiro
S
Tatsumi
Hideki
H
Nemoto
Soichi
S
Mori
Akio
A
D020121:5' Untranslated Regions / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D019169:Jurkat Cells / Q000187:drug effects / Q000378:metabolism*; D008213:Lymphocyte Activation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020825:T-Box Domain Proteins / Q000235:genetics / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018417:Th1 Cells / Q000166:cytology / Q000378:metabolism; D018418:Th2 Cells / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D000098815:T-bet Transcription Factor
D020121:5' Untranslated Regions; D018076:DNA, Complementary; C508598:IL4 protein, human; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D015847:Interleukin-4; D015759:Ionomycin; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate