Tandem AP-1-binding sites within the human beta-globin dominant control region function as an inducible enhancer in erythroid cells. (original) (raw)

  1. P A Ney,
  2. B P Sorrentino,
  3. K T McDonagh, and
  4. A W Nienhuis
  5. Clinical Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.

Abstract

A powerful enhancer has been mapped to an 18-bp DNA segment located 11 kb 5' to the human epsilon-globin gene within the dominant control or locus-activating region. This enhancer is inducible in K562 human erythroleukemia cells, increasing linked gamma-globin promoter/luciferase gene expression to 170-fold over an enhancerless construct. The enhancer consists of tandem AP-1-binding sites, phased 10 bp apart, which are both required for full activity. DNA-protein binding assays with nuclear extracts from induced cells demonstrate a high molecular weight complex on the enhancer. The formation of this complex also requires both AP-1 sites and correlates with maximal enhancer activity. Induction of the enhancer may have a role in the increase in globin gene transcription that characterizes erythroid maturation. Enhancer activity appears to be mediated by the binding of a complex of proteins from the jun and fos families to tandem AP-1 consensus sequences.

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