Pit-1 exhibits a unique promoter spacing requirement for activation and synergism

K. P. Smith, B. Liu, C. Scott, Z. D. Sharp

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

The developmentally regulated Pit-1 transcription factor is involved in the activation of prolactin, growth hormone, and TSHβ expression. Using templates with spacing mutations to program an in vitro transcription system, the activity of a single Pit-1 proximal binding site within the rat prolactin promoter was shown to have a unique bimodal distance requirement. Transcription activity rapidly decreased with each 5-base pair (bp) addition to the spacing between the binding site and the TATA box. When positioned 20 bp upstream from its normal -36 position in the prolactin promoter, the activity of the Pit-1 binding site is reduced to basal levels. Placement of the site at a position 30 bp upstream resulted in a return of Pit-1-mediated activation. Using transient transfection assays in GH3 cells, the prime bimodal sites are also a requirement for optimum expression of chimeric prolactin-luciferase reporter constructs. Interestingly, optimal synergism of transcription in vivo by the prolactin distal enhancer, containing four Pit- 1 binding sites and an estrogen-responsive element, is also sensitive to the placement of the proximal Pit-1 binding site. These data have important implications for Pit-1 activator function in pituitary cells and for general models of transcription synergism.

Original languageEnglish (US)
Pages (from-to)4484-4491
Number of pages8
JournalJournal of Biological Chemistry
Volume270
Issue number9
DOIs
StatePublished - 1995
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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