Lmo2/Tal1 and Gata factors act through hematopoietic elements, while Ets factors control the pP. (A) ChIP-chip analysis in myeloid progenitor cell line 416B performed with antibodies against histone H3 acetylation (H3K9ac) or transcription factors Lmo2, Tal1, Gata2, Fli1, and Sfpi1. MVista representation of mouse/human sequence conservation is shown on the top and annotations of promoters (gray), and the 9 candidate regulatory elements (black) are as in Figure 1. The y-axis represents the log 2 enrichment of ChIPed DNA over input DNA ranging from −1 to 5 or 3, respectively. The H3K9ac panel is derived from Figure 2, to highlight accessible areas in the Lmo2 locus of 416B cells. Specific binding of Tal1/Lmo2/Gata2 can be found to hematopoietic elements but not to the endothelial pP region. This is in contrast with Ets factors, which do bind the pP region. (B) Transactivation assays in 293T cells using the LMO2 pP and hematopoietic enhancer constructs. The pP can be transactivated by Ets factors Fli1 and Sfpi1, whereas the −75 element is transactivated by a multiprotein complex containing Tal1, LMO2, E47, Ldb1, and GATA1. Transactivation assays were performed in at least 2 biologic replicates and assayed in triplicates. The values shown for the −75 enhancer were normalized using the values obtained with the pP construct without enhancer. (C) Differential regulation of Lmo2 elements. Autoregulatory complexes composed of Lmo2, Tal1, and Gata factors activate distal hematopoietic elements (erythroid and FL), whereas Ets factors are acting on the endothelial promoter. Annotations are as in Figure 1.