FIG. 5.

(A and B) Analysis of developmental alterations of transcription factor occupancy and chromatin fine structure at the Pu.1 promoter (A) and the 3′ URE (B) by in vivo DMS and DNase I footprinting (as indicated). For more explanation, refer to the legend to Fig. 2. +OHT and −OHT, PUER cells with and without OHT induction, respectively; M, macrophages; G, Maxam-Gilbert G reaction with purified genomic DNA. (C) Results from a DMS in vivo footprinting experiment analyzing transcription factor occupancy at the 3′ URE in macrophages, 3T3 cells, and two independent cultures of myeloid progenitor cells (prog 1 and prog 2). (D to G) Results from ChIP assays examining the binding of PU.1, RUNX1, C/EBPb, and Fli-1 to the different Pu.1 cis-regulatory elements plus one control region in the absence of PU.1 (PU.1^−/−; PUER −OHT) and after 48 h of PU.1 induction (+OHT). The data shown are averages of results from two independent chromatin preparations analyzed in triplicate. RAW, RAW 264 cells; 5′H enh and 3′H enh, 5′ URE and 3′ URE, respectively.