Interleukin-12 induces expression of interferon regulatory factor-1 via signal transducer and activator of transcription-4 in human T helper type 1 cells.
IRF-1-deficient mice show a striking defect in the development of T helper 1 (Th1) cells. In the present report, we investigate the expression of IRF-1 during differentiation of human T helper cells. No significant differences of IRF-1 mRNA expression were found in established Th1 and Th2 cells; however, interleukin 12 (IL-12) induced a strong up-regulation of IRF-1 transcripts in Th1 but not in Th2 cells. We demonstrate that IL-12-induced up-regulation of IRF-1 is mediated by signal transducer and activator of transcription-4, which binds to the interferon (IFN)-gamma-activated sequence present in the promoter of the IRF-1 gene. Strong IL-12-dependent activation of a reporter gene construct containing the IRF-1 IFN-gamma-activated sequence element provides further evidence for the key role of signal transducer and activator of transcription-4 in the IL-12-induced up-regulation of IRF-1 transcripts in T cells. IRF-1 expression was strongly induced after stimulation of naive CD4(+) T cells via the T cell receptor, irrespective of the cytokines present at priming, indicating that this transcription factor does not play a major role in initiating a Th1-specific transcriptional cascade in differentiating helper T cells. However, our finding that IRF-1 is a target gene of IL-12 suggests that some of the IL-12-induced effector functions of Th1 cells may be mediated by IRF-1.
Laboratory of Immunology, Istituto Superiore di Sanità, I-00161 Rome, Italy.
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EM
Coccia
N
N
Passini
A
A
Battistini
C
C
Pini
F
F
Sinigaglia
L
L
Rogge
D051701:Activating Transcription Factor 4; D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000276:immunology; D006801:Humans; D050856:Interferon Regulatory Factor-1; D018664:Interleukin-12 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000276:immunology / Q000378:metabolism*; D015533:Transcriptional Activation / Q000276:immunology
C497109:ATF4 protein, human; D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D010750:Phosphoproteins; D014157:Transcription Factors; D051701:Activating Transcription Factor 4; D018664:Interleukin-12