Loss of ERE binding activity by estrogen receptor-α alters basal and estrogen-stimulated bone-related gene expression by osteoblastic cells

Volha Rudnik, Arunik Sanyal, Farhan A. Syed, David G. Monroe, Thomas C. Spelsberg, Merry Jo Oursler, Sundeep Khosla

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Estrogen receptor (ER)-α can signal either via estrogen response element (ERE)-mediated pathways or via alternate pathways involving protein-protein or membrane signaling. We previously demonstrated that, as compared to wild type (WT) controls, mice expressing a mutant ER-α lacking the ability to bind EREs (non-classical estrogen receptor knock-in (NERKI)) display significant impairments in the skeletal response to estrogen. To elucidate the mechanism(s) underlying these in vivo deficits, we generated U2OS cells stably expressing either VVT ER-α or the NERKI receptor. Compared to cells transfected with the control vector, stable expression of ER-α, even in the absence of E2, resulted in an increase in mRNA levels for alkaline phosphatase (AP, by 400%, P < 0.01) and a decrease in mRNA levels for insulin growth factor-I (IGF-I) (by 65%, P < 0.001), with no effects on collagen I (col I) or osteocalcin (OCN) mRNA levels. By contrast, stable expression of the NERKI receptor resulted in the suppression of mRNA levels for AP, col I, OCN, and IGF-I (by 62, 89, 60, and 70%, P < 0.001 ). While E2 increased mRNA levels of AP, OCN, col I, and IGF-I in ER-α cells, E2 effects in the NERKI cells on AP and OCN mRNA levels were attenuated, with a trend for E2 to inhibit col I mRNA levels. In addition, E2 had no effects on IGF-I mRNA levels in NERKI cells. Collectively, these findings indicate that ERE signaling plays a significant role in mediating effects of estrogen on osteoblastic differentiation markers and on IGF-I mRNA levels.

Original languageEnglish (US)
Pages (from-to)896-907
Number of pages12
JournalJournal of cellular biochemistry
Volume103
Issue number3
DOIs
StatePublished - Feb 15 2008

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Keywords

  • Estrogen receptor
  • NERKI
  • Osteoblasts
  • Signaling pathways

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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