Cron RQ, Zhou B, Brunvand MW, Lewis DB. Octamer proteins inhibit IL-4 gene transcription in normal human CD4 T cells.
Genes Immun 2001;
2:464-8. [PMID:
11781715 DOI:
10.1038/sj.gene.6363811]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2001] [Revised: 09/18/2001] [Accepted: 09/18/2001] [Indexed: 11/09/2022]
Abstract
The balance of Th1 (eg, interleukin-2 (IL-2)) and Th2 (eg, IL-4) cytokines produced by CD4 T cells markedly influences the outcome of the adaptive immune response. Although octamer transcription factor proteins increase IL-2 transcription in T cells, their role in IL-4 gene transcription remains controversial. We have previously shown and now confirm that the proximal octamer binding site of the human IL-4 promoter, which separates the two most proximal NFAT binding sites, is bound prior to, but not after, activation in vivo. Since these two NFAT sites are essential for optimal IL-4 promoter activity, this suggested that prior engagement by octamer proteins might prevent adjacent NFAT binding and inhibit IL-4 gene transcription. In support of this hypothesis, here we show that NFAT proteins are unable to bind to a combined octamer/NFAT site unless the octamer proteins are competed away. Moreover, activity of an IL-4 reporter gene mutated in the proximal octamer binding site is increased compared to the wild-type promoter in human peripheral blood CD4 T cells. In addition, over-expression of either Oct-1 or Oct-2 decreased wild-type IL-4 promoter activity, while increasing IL-2 promoter activity. No decrease in promoter activity was seen when Oct-1 or Oct-2 was over-expressed with the octamer-mutant IL-4 reporter gene. Thus, octamer proteins are candidates to promote a Th1 rather than Th2 pattern of cytokine gene expression by activated CD4 T cells.
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