Differential recruitment of glucocorticoid receptor phospho-isoforms to glucocorticoid-induced genes

J Steroid Biochem Mol Biol. 2008 Mar;109(1-2):150-7. doi: 10.1016/j.jsbmb.2008.01.002. Epub 2008 Jan 19.

Abstract

The human glucocorticoid receptor (GR) is phosphorylated on its N-terminus at three major sites (S203, S211 and S226) within activation function 1 (AF1). Although GR has been shown to assemble at glucocorticoid responsive elements (GREs) in the presence of hormone, the timing and specificity of GR phospho-isoform recruitment to receptor target genes has not been established. Using chromatin immunoprecipitation (ChIP) and GR phosphorylation site-specific antibodies, we examined GR phospho-isoform recruitment to several glucocorticoid-induced genes including tyrosine aminotransferase (tat) and sulfonyltransferase-1A1 (sult) in rat hepatoma cells, and the glucocorticoid-induced leucine zipper (gilz) gene in human U2OS cells. GR P-S211 and GR P-S226 isoforms were efficiently recruited to the tat, sult and gilz GREs in a hormone-dependent manner. In contrast, the GR P-S203 isoform displayed no significant recruitment to any GREs of the genes analyzed, consistent with its lack of nuclear accumulation. Interestingly, the kinetics of GR P-S211 and GR P-S226 recruitment differed among genes. Our findings indicate that GR phospho-isoforms selectively occupy GR target genes, and suggests gene specific requirements for GR phosphorylation in receptor-dependent transcriptional activation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Arylsulfotransferase / genetics
  • Base Sequence
  • Binding Sites / genetics
  • Cell Line, Tumor
  • DNA / genetics
  • DNA / metabolism
  • DNA Primers / genetics
  • Dexamethasone / pharmacology*
  • Humans
  • Phosphorylation
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Receptors, Glucocorticoid / chemistry
  • Receptors, Glucocorticoid / metabolism*
  • Transcription Factors / genetics
  • Transcriptional Activation / drug effects*
  • Tyrosine Transaminase / genetics

Substances

  • DNA Primers
  • Protein Isoforms
  • RNA, Messenger
  • Receptors, Glucocorticoid
  • TSC22D3 protein, human
  • Transcription Factors
  • Dexamethasone
  • DNA
  • Tyrosine Transaminase
  • Arylsulfotransferase