5′ regulatory region of a novel cytokine gene mediates selective activation by interferon γ

Abstract

A newly described member of the platelet factor 4 family of cytokine genes, mig, is selectively induced by interferon γ (IFN-γ), and not IFN-α, in the mouse macrophage-like cell line RAW 264.7. Treatment of RAW 264.7 cells with IFN-γ activated mig gene transcription as determined by nuclear run-on assays, mig genomic clones were isolated, and constructs containing genomic fragments that included the mig promoter region and the CAT reporter gene were prepared. In RAW 264.7 cells transfected with these constructs, CAT activity was found to be selectively induced by IFN-γ. A 278-bp genomic fragment containing 235 nucleotides 5′ of the transcription start site was sufficient for IFN-γ-selective induction of CAT activity. Analysis of 5′ deletion mutants localized a region essential for activation by IFN-γ to within 64 nucleotides extending from -235 to -172. A genomic fragment containing this sequence was capable of conferring IFN-γ inducibility to constructs with a heterologous promoter.