FIG. 6.
IRF-4 is required for Igκ germ line transcription and promotes enhancer histone acetylation. (A) IRF-4 RNAi perturbs Igκ transcription. Pre-B-cell lines were stably transduced with one of two IRF-4 shRNAi constructs (6-D1 or 9-H4). Wild-type (WT) or IRF-4 knockdown cell lines were treated with or without 10 μM STI-571 for 6 h. The relative expression levels of IRF-4 and Igκ transcripts were determined by quantitative RT-PCR. IRF-4 and Igκ transcript levels were normalized to EF1α. (B) Effect of IRF-4 knockdown on Igκ enhancer chromatin modification. Mononucleosomes were prepared from chromatin of wild-type or IRF-4KD pre-B-cell lines treated with or without STI-571 for 6 h. Enrichment of sequences associated with acetyl-H3 or acetyl-H4 histones at κEi or κE3′ was determined by ChIP. Relative acetylation was plotted as IP/input. The G6PD and T4D loci serve as internal controls for an active and a silent locus, respectively.