Tumor necrosis factor receptor 1 (TNFR1)-associated death domain protein (TRADD) is essential in recruiting signaling molecules to the TNFR1 receptor complex. Interferon-γ (IFN-γ) is a potent activator of macrophages and uses signal transducer and activator of transcription 1-α (STAT1-α) for signal transduction. Here we demonstrate that IFN-γ induces the formation of a nuclear-localized TRADD-STAT1-α complex. IFN-γ-mediated STAT1-α phosphorylation was prolonged in cells with reduced TRADD expression. Moreover, we noted an increase in IFN-γ-mediated STAT1-α DNA-binding activity, nuclear presence and transcriptional potential in the TRADD knockdown cells. These data indicate that TRADD may be involved in IFN-γ signaling by forming a complex with STAT1-α within the nucleus and regulating IFN-γ-mediated STAT1-α activation.
