Glucocorticoid receptor phosphorylation differentially affects target gene expression.
The glucocorticoid receptor (GR) is phosphorylated at multiple sites within its N terminus (S203, S211, S226), yet the role of phosphorylation in receptor function is not understood. Using a range of agonists and GR phosphorylation site-specific antibodies, we demonstrated that GR transcriptional activation is greatest when the relative phosphorylation of S211 exceeds that of S226. Consistent with this finding, a replacement of S226 with an alanine enhances GR transcriptional response. Using a battery of compounds that perturb different signaling pathways, we found that BAPTA-AM, a chelator of intracellular divalent cations, and curcumin, a natural product with antiinflammatory properties, reduced hormone-dependent phosphorylation at S211. This change in GR phosphorylation was associated with its decreased nuclear retention and transcriptional activation. Molecular modeling suggests that GR S211 phosphorylation promotes a conformational change, which exposes a novel surface potentially facilitating cofactor interaction. Indeed, S211 phosphorylation enhances GR interaction with MED14 (vitamin D receptor interacting protein 150). Interestingly, in U2OS cells expressing a nonphosphorylated GR mutant S211A, the expression of IGF-binding protein 1 and interferon regulatory factor 8, both MED14-dependent GR target genes, was reduced relative to cells expressing wild-type receptor across a broad range of hormone concentrations. In contrast, the induction of glucocorticoid-induced leucine zipper, a MED14-independent GR target, was similar in S211A- and wild-type GR-expressing cells at high hormone levels, but was reduced in S211A cells at low hormone concentrations, suggesting a link between GR phosphorylation, MED14 involvement, and receptor occupancy. Phosphorylation also affected the magnitude of repression by GR in a gene-selective manner. Thus, GR phosphorylation at S211 and S226 determines GR transcriptional response by modifying cofactor interaction. Furthermore, the effect of GR S211 phosphorylation is gene specific and, in some cases, dependent upon the amount of activated receptor.
Chen
Weiwei
W
Department of Pharmacology, and the NYU Cancer Institute, NYU School of Medicine, 550 First Avenue, New York, New York 10016, USA.
Dang
Thoa
T
Blind
Raymond D
RD
Wang
Zhen
Z
Cavasotto
Claudio N
CN
Hittelman
Adam B
AB
Rogatsky
Inez
I
Logan
Susan K
SK
Garabedian
Michael J
MJ
D000595:Amino Acid Sequence; D045163:Antibodies, Phospho-Specific / Q000494:pharmacology; D045744:Cell Line, Tumor; D003474:Curcumin / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008024:Ligands; D056892:Mediator Complex; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D017433:Protein Structure, Secondary; D011965:Receptors, Glucocorticoid / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
D045163:Antibodies, Phospho-Specific; D008024:Ligands; C492160:MED14 protein, human; D056892:Mediator Complex; D010455:Peptides; D011965:Receptors, Glucocorticoid; D015534:Trans-Activators; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D010768:Phosphoserine; D004533:Egtazic Acid; D003474:Curcumin