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J Immunol. 2002 Mar 1;168(5):2365-70.

Txk, a member of nonreceptor tyrosine kinase of Tec family, acts as a Th1 cell-specific transcription factor and regulates IFN-gamma gene transcription.

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1
Department of Immunology and Medicine, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Kanagawa 216-8511, Japan.

Abstract

Precise mechanisms responsible for Th1 cell activation and differentiation are not fully elucidated. We have recently reported that Txk, a member of Tec family nonreceptor tyrosine kinase, is expressed on Th1/Th0 cells, and Txk regulates specifically IFN-gamma gene expression. In this study, we found that Txk bound to IFN-gamma promoter region. Txk transfection increased transcriptional activity of IFN-gamma promoter plus luciferase constructs severalfold, including IFN-gamma promoter -538, -208, and -53. IFN-gamma promoter -39 was refractory to the Txk transfection. The actual site to which Txk bound was the element consisting of -53 and -39 bp from the transcription start site of human IFN-gamma gene, a site distinct from several previously characterized binding sites. We found that the entire -53/-39 region was necessary for the binding to and function of Txk, because mutant promoter oligoDNA that contained contiguous five base substitutions dispersed throughout the -53/-39 inhibited the binding, and the mutant promoters did not respond to the Txk transfection. Similar sequences of this element are found within the 5' flanking regions of several Th1 cell-associated protein genes. Thus, Txk is expressed on Th1/Th0 cells with the IFN-gamma production and acts as a Th1 cell-specific transcription factor.

PMID:
11859127
DOI:
10.4049/jimmunol.168.5.2365
[Indexed for MEDLINE]
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