Role of ZBP-89 in globin gene regulation and recruitment of HATs. (A) Change in globin gene expression on ZBP-89 depletion in uninduced K562 cells. Relative mRNA levels for ZBP-89, HBG (γ-globin), and HBA (α-globin) normalized to Gapdh are shown in uninduced K562 cells transduced with either the empty vector, or ZBP-89 sh1 and sh2. Levels are shown relative to the empty vector control and represent the mean of 3 independent experiments ± SEM. (B) Quantitative ChIP assays for ZBP-89, Gcn5, and AcH3 enrichment levels at β-globin HS3 and α-globin HS-40 in human EryP cells transduced with the empty vector or ZBP-89 sh1. The cells were harvested on day 6 of differentiation. The data represent the enrichment relative to β-actin exon 6 and are the mean of 2 biologic duplicates and 3 experimental repeats ± SEM. (D) Effect of VPA on globin gene expression changes induced by ZBP-89 depletion. Relative mRNA levels for ZBP-89, HBG (γ-globin), HBB (β-globin), and HBA (α-globin) in human EryP cells transduced with the empty vector or ZBP-89 sh1. Transduced and selected cells were divided into 2 cultures and incubated with either 1μM VPA in PBS or PBS alone. Cells were harvested 72 hours later. Levels are shown relative to the empty vector control and represent the mean of 3 experiments ± SEM.