Impact of Thyroid Hormones on Estrogen Receptor α-Dependent Transcriptional Mechanisms in Ventromedial Hypothalamus and Preoptic Area

Neuroendocrinology. 2015;101(4):331-46. doi: 10.1159/000381459. Epub 2015 Mar 13.

Abstract

Elevated levels of thyroid hormones (TH) reduce estradiol (E2)-dependent female sexual behavior. E2 stimulates progesterone receptor (Pgr) and oxytocin receptor (Oxtr) within the ventromedial hypothalamus and preoptic area, critical hypothalamic nuclei for sexual and maternal behavior, respectively. Here, we investigated the impact of TH on E2-dependent transcriptional mechanisms in female mice. First, we observed that triiodothyronine (T3) inhibited the E2 induction of Pgr and Oxtr. We hypothesized that differences in histone modifications and receptor recruitment could explain the influence of TH on E2-responsive Pgr and Oxtr expression. We observed that histone H3 acetylation (H3Ac) and methylation (H3K4me3) was gene and brain-region specific. We then analyzed the recruitment of estrogen receptor α (ERα) and TH receptor α (TRα) on the putative regulatory sequences of Pgr and Oxtr. Interestingly, T3 inhibited E2-induced ERα binding to a specific Pgr enhancer site, whereas TRα binding was not affected, corroborating our theory that the competitive binding of TRα to an ERα binding site can inhibit ERα transactivation and the subsequent E2-responsive gene expression. On the Oxtr promoter, E2 and T3 worked together to modulate ERα and TRα binding. Finally, the E2-dependent induction of cofactors was reduced by hypothyroidism and T3. Thus, we determined that the Pgr and Oxtr promoter regions are responsive to E2 and that T3 interferes with the E2 regulation of Pgr and Oxtr expression by altering the recruitment of receptors to DNA and changing the availability of cofactors. Collectively, our findings provide insights into molecular mechanisms of response to E2 and TH interactions controlling sex behavior in the hypothalamus.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation / drug effects
  • Animals
  • DNA Methylation / drug effects
  • DNA Methylation / physiology
  • Estradiol / metabolism
  • Estrogen Receptor alpha / metabolism*
  • Female
  • Histones / drug effects
  • Histones / metabolism
  • Hormones / pharmacology
  • Hypothalamus / drug effects
  • Hypothalamus / metabolism*
  • Mice
  • Preoptic Area / drug effects
  • Preoptic Area / metabolism*
  • Promoter Regions, Genetic
  • Receptors, Oxytocin / genetics
  • Receptors, Oxytocin / metabolism*
  • Receptors, Progesterone / genetics
  • Receptors, Progesterone / metabolism*
  • Thyroid Hormone Receptors alpha / metabolism
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / physiology
  • Triiodothyronine / pharmacology

Substances

  • Estrogen Receptor alpha
  • Histones
  • Hormones
  • OXTR protein, mouse
  • Receptors, Oxytocin
  • Receptors, Progesterone
  • Thyroid Hormone Receptors alpha
  • Triiodothyronine
  • Estradiol