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. Author manuscript; available in PMC: 2019 May 1.
Published in final edited form as: Curr Opin Hematol. 2018 May;25(3):189–195. doi: 10.1097/MOH.0000000000000415

FIGURE 1.

FIGURE 1

Integrative model illustrating how transcription factors, enhancers, and chromatin looping work together to recruit Pol II to promoters during erythropoiesis. The erythroid master regulator transcription factors (GATA1, KLF1, and TAL1) predominantly bind to enhancers (denoted by purple rectangles) in various assemblages in conjunction with accessory proteins, including E2A, LDB1, and LMO2. E2A is a member of the E protein family of helix-loop-helix transcription factors that forms a heterodimer with TAL1 to bind DNA. With LMO2 tethering LDB1 to erythroid transcription factors, LDB1 facilitates higher order complex assembly and chromatin looping interactions via LDB1 homodimerization [8]. EPO-EPOR-JAK2 signaling directly activates STAT5, which integrates with the master regulators by cooccupying several hundred GATA1 bound enhancers [34■■]. Transcription factors and enhancers interact within the confines of topologically associated chromatin domains that are structurally held together by CTCF and cohesin, as well as other regulatory and structural factors.