Estrogen reduces lipid content in the liver exclusively from membrane receptor signaling

Sci Signal. 2013 May 21;6(276):ra36. doi: 10.1126/scisignal.2004013.

Abstract

Estrogen induces signal transduction through estrogen receptor α (ERα), which localizes to both the plasma membrane and nucleus. Using wild-type mice, ERα knockout (ERKO) mice, or transgenic mice expressing only the ligand-binding domain of ERα exclusively at the plasma membrane (MOER), we compared the transcriptional profiles of liver tissue extracts after mice were injected with the ERα agonist propyl-pyrazole-triol (PPT). The expression of many lipid synthesis-related genes was comparably decreased in livers from MOER or wild-type mice but was not suppressed in ERKO mice, indicating that only membrane-localized ERα was necessary for their suppression. Cholesterol, triglyceride, and fatty acid content was decreased only in livers from wild-type and MOER mice exposed to PPT, but not in the livers from the ERKO mice, validating the membrane-driven signaling pathway on a physiological level. PPT-triggered activation of ERα at the membrane induced adenosine monophosphate-activated protein kinase to phosphorylate sterol regulatory element-binding factor 1 (Srebf1), preventing its association with and therefore its proteolytic cleavage by site-1 protease. Consequently, Srebf1 was sequestered in the cytoplasm, preventing the expression of cholesterol synthesis-associated genes. Thus, we showed that inhibition of gene expression mediated by membrane-localized ERα caused a metabolic phenotype that did not require nuclear ERα.

Publication types

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

MeSH terms

  • Adenylate Kinase / metabolism
  • Animals
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Estrogen Receptor alpha / metabolism
  • Estrogens / physiology*
  • Lipids / analysis*
  • Liver / cytology
  • Liver / enzymology
  • Liver / metabolism*
  • Mice
  • Mice, Knockout
  • Protein Binding
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction*
  • Sterol Regulatory Element Binding Protein 1 / metabolism

Substances

  • Estrogen Receptor alpha
  • Estrogens
  • Lipids
  • Receptors, Cell Surface
  • Srebf1 protein, mouse
  • Sterol Regulatory Element Binding Protein 1
  • Cyclic AMP-Dependent Protein Kinases
  • Adenylate Kinase