| First Author | Ohmori Y | Year | 1997 |
| Journal | J Immunol | Volume | 159 |
| Issue | 11 | Pages | 5474-82 |
| PubMed ID | 9548487 | Mgi Jnum | J:44269 |
| Mgi Id | MGI:1099648 | Doi | 10.4049/jimmunol.159.11.5474 |
| Citation | Ohmori Y, et al. (1997) IL-4-induced STAT6 suppresses IFN-gamma-stimulated STAT1-dependent transcription in mouse macrophages. J Immunol 159(11):5474-82 |
| abstractText | IL-4 suppresses the IFN-gamma-induced expression of the IFN regulatory factor-1 (IRF-1) gene, and this suppression is attenuated by increasing the amount of IFN-gamma. The effects of IFN-gamma and IL-4 on transcription of a reporter gene under control of a 1.3-kb fragment from the IRF-1 gene promoter or the STAT binding element (SBE) from this gene in the context of a heterologous promoter are similar to their effects on the endogenous IRF-1 gene. IFN-gamma-dependent transcription of reporter gene is suppressed by IL-4, but IL-4 alone has no trans-activating function. IL-4 treatment does not inhibit the tyrosine phosphorylation or nuclear translocation of IFN-gamma- activated STAT1. Rather, IFN-gamma and IL-4 independently activate STAT1 and STAT6, respectively, and both proteins bind to the IRF-1 SBE in homodimeric form. The affinity of STAT1 for the IRF-1 SBE is higher than the affinity of STAT6, as measured by competition with unlabeled oligonucleotide. These observations suggest that IL-4 may suppress IFN- gamma-stimulated transcription of the IRF-1 gene by activation of STAT6, which can compete with STAT1 for occupancy of the IRF-1 SBE when STAT1 levels are low. Suppression may be attenuated as the quantity of STAT1 relative to that of STAT6 increases in cells treated with increasing amounts of IFN-gamma and displaces STAT6. |
