FIGURE 4.
ISRE element of PML promoter gene is involved in basal transcription of PML gene. Shown is luciferase reporter gene activity under the control of PML gene promoter (−809 bp/+633 bp relative to transcription start) in HeLa cells with an intact or deleted (−595 bp/−628 bp) ISRE DNA binding site (cells were harvested 24 h after transfection; the average values representing three independent experiments are given as arbitrary units (AU); error bars represent S.E.) (A), with or without IL6-depleting antibody (IL6 AB; 2 μg/ml; average values representing two independent experiments are given as arbitrary units; error bars represent S.E.) (B), and with or without IL6 treatment (5000 pg/ml; average values representing two independent experiments are given as -fold induction; error bars represent S.E.) (C). Asterisks (*, **, and ***) represent p values <0.05, <0.01, and <0.005, respectively. D, shown is evaluation of STAT3 binding to PML ISRE element in untreated BJ, HeLa, and U2OS cells and in HeLa and U2OS cells treated with IL6 for 0.5, 1, and 6 h in HeLa and 48 h in U2OS cells, respectively, quantified with RT-qPCR after chromatin immunoprecipitation. The values quantified with RT-qPCR represent average of two independent experiments performed in triplicate and are expressed as -fold induction relative to HeLa untreated cells.