USF1 recruits hSET1 and NURF complexes to the human α-spectrin barrier element. (A) Schematic representation of the human α-spectrin gene. Gray boxes indicate locations of primer sets used in ChIP analysis. (B-C) ChIP analysis of USF1, hSET1, and BPTF binding at the 183-bp barrier element of the α-spectrin gene in human erythroid progenitor K562 cells (B) and cultured human primary erythroid cells (C). (D) The effect of hSET1 KD (left) and expression of a dominant-negative USF (AUSF1; right) in K562 cells was analyzed by Western blot. AUSF1 was detected by antibody specific to the C-terminal epitope. (E) ChIP analysis of dimethyl H3K4 in the 183-bp barrier element of the α-spectrin gene in human erythroid K562 cells comparing vector control and hSET1 KD clones. The relative enrichment of dimethyl H3K4 by ChIP analysis was determined in 3 independent experiments. (F) ChIP analysis of dimethyl H3K4 in the 183-bp barrier element of the α-spectrin gene in human erythroid K562 cells harboring the vector control or AUSF. (G-H) ChIP analysis of hSET1 (G) and BPTF (H) recruitment after overexpression of AUSF1 in K562 cells. *P < .01 by Student t test. Shown are the means ± SEM of 3 independent experiments.