Glucocorticoid Receptor Phosphorylation Modulates Transcription Efficacy Through GRIP-1 Recruitment

Biochemistry. 2010 Feb 9;49(5):972-85. doi: 10.1021/bi901956s.

Abstract

The role of GR phosphorylation in modulating GR-mediated transcription is not fully understood. Here we show that the hGR is rapidly phosphorylated at S211 and S226 in response to the synthetic agonist dexamethasone (dex) in COS-1 cells. Using a triple phosphorylation mutant hGR construct, we demonstrate that phosphorylation at one or more S residues (from S203, S211, and S226) is required for maximal hGR-mediated transcriptional activation on the MMTV promoter in response to dex in COS-1 cells, but that this effect is promoter selective. Phosphorylation at these residues does not affect unliganded or agonist-induced hGR degradation, suggesting that the mechanism whereby hGR phosphorylation at these residues regulates GR-mediated transactivation via a GRE does not involve changes in GR half-life. We have previously shown a direct correlation between efficacy for transactivation and interaction of the hGR with glucocorticoid receptor interacting protein-1 (GRIP-1). Here we show by pull-down assays in the absence and presence of glucocorticoid response elements (GREs) that phosphorylation of the hGR is required for GR-GRIP-1 interaction. Chromatin immunoprecipitation (ChIP) assays revealed that hGR phosphorylation at one or more S residues (from S226, S211, and S203) is required for the recruitment of GRIP-1 to the synthetic MMTV promoter as well as to the endogenous GRE-containing glucocorticoid-induced leucine zipper (GILZ) promoter in intact COS-1 cells, but not for nuclear localization. Our results support the conclusion that phosphorylation at S203, S211, and/or S226 of the hGR is required for a maximal transcriptional response via the synthetic MMTV and endogenous GILZ GREs in COS-1 cells, to enable recruitment of GRIP-1 to the hGR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Chlorocebus aethiops
  • Dexamethasone / metabolism
  • Dexamethasone / pharmacology
  • Humans
  • Mammary Tumor Virus, Mouse / genetics
  • Mammary Tumor Virus, Mouse / metabolism
  • Nuclear Receptor Coactivator 2 / metabolism*
  • Nuclear Receptor Coactivator 2 / physiology
  • Phosphorylation / genetics
  • Promoter Regions, Genetic / genetics
  • Protein Binding / genetics
  • Protein Transport / genetics
  • Rats
  • Receptors, Glucocorticoid / agonists
  • Receptors, Glucocorticoid / genetics
  • Receptors, Glucocorticoid / metabolism*
  • Response Elements / genetics
  • Serine / genetics
  • Serine / metabolism
  • Transcriptional Activation / genetics

Substances

  • NCOA2 protein, human
  • Nuclear Receptor Coactivator 2
  • Receptors, Glucocorticoid
  • Serine
  • Dexamethasone