Estrogen- and xenoestrogen-induced ERK signaling in pituitary tumor cells involves estrogen receptor-α interactions with G protein-αi and caveolin I

Cheryl S. Watson, Yow Jiun Jeng, Guangzhen Hu, Ann Wozniak, Nataliya Bulayeva, Jutatip Guptarak

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Multiple physiologic estrogens (estradiol, estriol, and estrone), as well as xenoestrogenic compounds (including alkylphenols and bisphenol A), can act via nongenomic signaling initiated by liganding of the plasma membrane estrogen receptor-α (mERα). We examined heterotrimeric G protein involvement leading to extracellular-regulated kinase (ERK) activation in GH3/B6/F10 rat anterior pituitary tumor cells that express abundant mERα, and smaller amounts of mERβ and GPR30. A combination of microarrays, immunoblots, and quantitative immunoassays demonstrated the expression of members of all α, β, and γ G protein classes in these cells. Use of selective inhibitors showed that the G αi subtype was the primary initiator of downstream ERK signaling. Using antibodies against the GTP-bound form of G α protein subtypes I and s, we showed that xenoestrogens (bisphenol A, nonylphenol) activated G αi at 15-30 s; all alkylphenols examined subsequently suppressed activation by 5 min. GTP-activation of G αi for all estrogens was enhanced by irreversible cumulative binding to GTPγS. In contrast, G αs was neither activated nor deactivated by these treatments with estrogens. ERα and G αi co-localized outside nuclei and could be immuno-captured together. Interactions of ERα with G αi and caveolin I were demonstrated by epitope proximity ligation assays. An ERα/β antagonist (ICI182780) and a selective disruptor of caveolar structures (nystatin) blocked estrogen-induced ERK activation. Conclusions: Xenoestrogens, like physiologic estrogens, can evoke downstream kinase signaling involving selective interactions of ERα with G αi and caveolin I, but with some different characteristics, which could explain their disruptive actions.

Original languageEnglish (US)
Pages (from-to)424-432
Number of pages9
JournalSteroids
Volume77
Issue number5
DOIs
StatePublished - Apr 1 2012

Keywords

  • Alkylphenols
  • Bisphenol A
  • GH3 cells
  • GPR30
  • Membrane estrogen receptor
  • Nongenomic

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology
  • Pharmacology
  • Clinical Biochemistry
  • Organic Chemistry

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