Interaction between PU.1 and another Ets family transcription factor promotes macrophage-specific Basal transcription initiation

I L Ross, X Yue, M C Ostrowski, D A Hume

Research output: Contribution to journalArticlepeer-review

Abstract

Numerous macrophage-restricted promoters lack TATA boxes or other conventional initiation motifs but contain high affinity binding sites (PU boxes) for the macrophage-restricted Ets family transcription factor PU.1. In RAW264 murine macrophages, multimerized PU boxes were not active as enhancers when placed upstream of a minimal promoter. To model their role in basal promoters, we inserted PU boxes into a promoterless luciferase reporter plasmid. Two sites, regardless of orientation, were necessary and sufficient to direct reporter gene expression in transient transfections of the RAW264 macrophage-like cell line. This activity was absent in transfected 3T3 fibroblasts but could be induced by PU.1 coexpression. Both the model promoter and the macrophage-specific mouse and human c-fms promoters were activated in RAW264 cells by other Ets family transcription factors, Ets-2 and Elf-1. In fibroblasts, the effects of PU.1 and Ets-2 were multiplicative, whereas overexpression of PU.1 in RAW264 cells reduced activation of c-fms or model promoters by the other Ets factors. The PU.1 and Ets-2 binding sites of the mouse c-fms promoter have been located by DNase footprinting. A conserved Ets-like motif at the transcription site, CAGGAAC, that bound only weakly to PU.1, was identified as an additional critical basal c-fms promoter element. Comparison of studies on the model promoter, c-fms and other myeloid promoters provides evidence for a conserved mechanism that involves three separate and functionally distinct Ets-like motifs.
Original languageEnglish
Pages (from-to)6662-9
Number of pages8
JournalJournal of Biological Chemistry
Volume273
Issue number12
Publication statusPublished - 20 Mar 1998

Keywords

  • 3T3 Cells
  • Animals
  • Binding Sites
  • DNA Footprinting
  • Enhancer Elements, Genetic
  • HeLa Cells
  • Humans
  • Macrophages
  • Mice
  • Promoter Regions, Genetic
  • Protein Binding
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-ets
  • Receptor, Macrophage Colony-Stimulating Factor
  • Trans-Activators
  • Transcription Factors
  • Transcription, Genetic
  • Transfection

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