Wnt signaling in estrogen-induced lactotroph proliferation

Adam Giles, Frederic Madec, Sönke Friedrichsen, Karen Featherstone, Tom Chambers, Claire V Harper, Julia Resch, Georg Brabant, Julian R E Davis

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Prolactinomas are the most common type of functioning pituitary adenoma in humans, but the control of lactotroph proliferation remains unclear. Here, using microarray analysis, we show that estrogen treatment increased expression of Wnt4 mRNA in adult Fischer rat pituitary tissue. Dual immunofluorescence analysis revealed that Wnt4 expression was not confined to lactotrophs, but that it was expressed in all anterior pituitary cell types. Estradiol induced proliferation in the somatolactotroph GH3 cell line, in parallel with Wnt4 mRNA and protein induction. A reporter gene assay for TCF- and LEF-dependent transcription revealed that there was no activation of the canonical Wnt pathway in GH3 cells upon stimulation with Wnt-conditioned culture medium or coexpression of constitutively active mutant β-catenin. Expression of β-catenin in both GH3 cells and normal rat anterior pituitary cells was restricted to the cell membrane and was unaltered by treatment with estradiol, with no nuclear β-catenin being detected under any of the conditions tested. We show for the first time that Wnt4 affects non-canonical signaling in the pituitary by inhibiting Ca(2+) oscillations in GH3 cells, although the downstream effects are as yet unknown. In summary, Wnt4 is expressed in the adult pituitary gland, and its expression is increased by estrogen exposure, suggesting that its involvement in adult tissue plasticity is likely to involve β-catenin-independent signaling pathways.

Original languageEnglish
Pages (from-to)540-7
Number of pages8
JournalJournal of Cell Science
Volume124
Issue numberPt 4
DOIs
Publication statusPublished - 15 Feb 2011

Keywords

  • Animals
  • Calcium/metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Estrogens/metabolism
  • Female
  • Gene Expression Regulation
  • Humans
  • Lactotrophs/cytology
  • Rats
  • Rats, Inbred F344
  • Signal Transduction
  • Wnt Proteins/genetics
  • Wnt4 Protein
  • beta Catenin/genetics

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  • Cite this

    Giles, A., Madec, F., Friedrichsen, S., Featherstone, K., Chambers, T., Harper, C. V., Resch, J., Brabant, G., & Davis, J. R. E. (2011). Wnt signaling in estrogen-induced lactotroph proliferation. Journal of Cell Science, 124(Pt 4), 540-7. https://doi.org/10.1242/jcs.078642