Fig. 4

Interferon regulatory factor (IRF)-1 participates in interferon (IFN)-induced expression of SMN and SMNc genes. (A) Nuclear extracts prepared as described in “Materials and Methods” from untreated (lanes 1, 5), IFN-β-treated (lanes 2–4), or IFN-γ-treated (lanes 6–8) were assayed for specific binding activity to an oligonucleotide probe corresponding to SMN fragment 2 224 to 2 202 (9), after a 30 min preincubation without (lanes 1, 2, 5, 6) or with rabbit affinity-purified polyclonal antibodies against human IRF-1 (lanes 3, 7) or signal transducers and activators of transcription (Stat1; lanes 4, 8). Arrows indicate C1-, C2-, and C3-specific protein-DNA complexes in IFN-β-treated cells and C4-, C5-, and C6-specific protein-DNA complexes in IFN-γ-treated cells. (B) Total RNA from A172 cells treated for 4 hr and 8 hr, with medium alone (control; C) or in the presence of IFN-β (1000 U/ml) or IFN-γ (1000 U/ml) was reverse-transcribed and polymerase chain reaction (PCR) coamplification was performed for IRF-1 and β-actin genes, as described in “Materials and Methods.” The products were analyzed on a 2% agarose gel and visualized by ethidium bromide staining.