IRF-8/ICSBP and IRF-1 cooperatively stimulate mouse IL-12 promoter activity in macrophages.
IRF-8/ICSBP and IRF-1 are IRF family members whose expression is induced in response to IFN-gamma in macrophages. IL-12 is a cytokine produced in macrophages that plays a critical role in host defense. IFN-gamma and bacterial lipopolysaccharide (LPS) induce IL-12p40 transcription, which is necessary for the production of IL-12. We have previously shown that IL-12p40 expression is impaired in ICSBP-deficient mice and that transfection of ICSBP together with IRF-1 can activate IL-12p40 expression in mouse macrophage cells. To further study the role of ICSBP and IRF-1, we investigated murine IL-12p40 promoter activity in the macrophage cell line RAW 264.7. We show here that co-transfection of ICSBP and IRF-1 synergistically stimulates IL-12 promoter activity to a level comparable to that induced by IFN-gamma/LPS. Mutation of the Ets or NFkappaB site previously shown to be important for IL-12p40 transcription did not abolish the activation by ICSBP and IRF-1. However, mutation of the ISRE-like site found downstream from the NFkappaB and C/EBP sites abrogated the activation by ICSBP and IRF-1. Together, these results indicate that ICSBP and IRF-1 cooperatively stimulate murine IL-12 transcription through a novel regulatory element in the murine promoter.
Masumi
Atsuko
A
Department of Safety Research on Biologics, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama-shi, Tokyo, Japan. amasumi@nih.go.jp
Tamaoki
Satoshi
S
Wang
I Ming
IM
Ozato
Keiko
K
Komuro
Katsutoshi
K
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology*; D050856:Interferon Regulatory Factor-1; D050835:Interferon Regulatory Factors; D018664:Interleukin-12 / Q000235:genetics*; D053762:Interleukin-12 Subunit p40; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000502:physiology; D010750:Phosphoproteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000235:genetics*; D012097:Repressor Proteins / Q000502:physiology*; D020218:Response Elements; D015534:Trans-Activators / Q000502:physiology; D015533:Transcriptional Activation; D000099185:Interferon Regulatory Factor-8
D004268:DNA-Binding Proteins; D050856:Interferon Regulatory Factor-1; D050835:Interferon Regulatory Factors; D018664:Interleukin-12; D053762:Interleukin-12 Subunit p40; D009687:Nuclear Proteins; D010750:Phosphoproteins; D021122:Protein Subunits; D012097:Repressor Proteins; D015534:Trans-Activators; D000099185:Interferon Regulatory Factor-8; C494258:Irf1 protein, mouse