Tumor necrosis factor-alpha activates the human prolactin gene promoter via nuclear factor-kappaB signaling

Sönke Friedrichsen, Claire V Harper, Sabrina Semprini, Michael Wilding, Antony D Adamson, Dave G Spiller, Glyn Nelson, John J Mullins, Michael R H White, Julian R E Davis

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

Pituitary function has been shown to be regulated by an increasing number of intrapituitary factors, including cytokines. Here we show that the important cytokine TNF-alpha activates prolactin gene transcription in pituitary GH3 cells stably expressing luciferase under control of 5 kb of the human prolactin promoter. Similar regulation of the endogenous rat prolactin gene by TNF-alpha in GH3 cells was confirmed using real-time PCR. Luminescence microscopy revealed heterogeneous dynamic response patterns of promoter activity in individual cells. In GH3 cells treated with TNF-alpha, Western blot analysis showed rapid inhibitory protein kappaB (IkappaBalpha) degradation and phosphorylation of p65. Confocal microscopy of cells expressing fluorescence-labeled p65 and IkappaBalpha fusion proteins showed transient cytoplasmic-nuclear translocation and subsequent oscillations in p65 localization and confirmed IkappaBalpha degradation. This was associated with increased nuclear factor kappaB (NF-kappaB)-mediated transcription from an NF-kappaB-responsive luciferase reporter construct. Disruption of NF-kappaB signaling by expression of dominant-negative variants of IkappaB kinases or truncated IkappaBalpha abolished TNF-alpha activation of the prolactin promoter, suggesting that this effect was mediated by NF-kappaB. TNF-alpha signaling was found to interact with other endocrine signals to regulate prolactin gene expression and is likely to be a major paracrine modulator of lactotroph function.

Original languageEnglish
Pages (from-to)773-81
Number of pages9
JournalEndocrinology
Volume147
Issue number2
DOIs
Publication statusPublished - 1 Feb 2006

Keywords

  • Animals
  • Cell Line, Tumor
  • Gene Expression Regulation/physiology
  • Genes, Reporter
  • Humans
  • NF-kappa B/metabolism
  • Pituitary Gland/cytology
  • Prolactin/genetics
  • Promoter Regions, Genetic/genetics
  • Rats
  • Signal Transduction/physiology
  • Transfection
  • Tumor Necrosis Factor-alpha/physiology

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