Dataset Information

Phosphorylation of Farnesoid X Receptor at Serine 154 Links Ligand Activation With Degradation.

ABSTRACT: Comparison of 11 human nuclear receptor amino acid sequences revealed a conserved phosphorylation motif within their DNA-binding domains as an intramolecular signal that regulates proteolytic degradation. Nuclear receptors use this signal to either degrade or proscribe degradation through either the proteasome or nonproteasome pathways. A phosphomimetic farnesoid X receptor (FXR) S154D mutant neither bound to nor trans-activated an FXR-response element-driven reporter gene and was rapidly degraded in COS-1 cells. Ectopically expressed FXR had increased Ser154 phosphorylation in COS-1 cells after ligand treatment, and knock-down of the nuclear vaccinia-related kinase 1 (VRK1) greatly reduced this phosphorylation. FXR was phosphorylated at Ser154 in the nucleus of centrilobular hepatocytes only in ligand-treated mice. Thus, FXR Ser154 phosphorylation is a rheostat for activation and subsequent degradation that controls receptor levels and activity.

SUBMITTER: Hashiguchi T

PROVIDER: S-EPMC5045495 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Phosphorylation of Farnesoid X Receptor at Serine 154 Links Ligand Activation With Degradation.

Hashiguchi Takuyu T Arakawa Shingo S Takahashi Shogo S Gonzalez Frank J FJ Sueyoshi Tatsuya T Negishi Masahiko M

Molecular endocrinology (Baltimore, Md.) 20160829 10

Comparison of 11 human nuclear receptor amino acid sequences revealed a conserved phosphorylation motif within their DNA-binding domains as an intramolecular signal that regulates proteolytic degradation. Nuclear receptors use this signal to either degrade or proscribe degradation through either the proteasome or nonproteasome pathways. A phosphomimetic farnesoid X receptor (FXR) S154D mutant neither bound to nor trans-activated an FXR-response element-driven reporter gene and was rapidly degrad ...[more]

PMID: 27571290

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Project description:In response to environmental stressors and a variety of inflammatory cytokines, p38 MAPKs become directly activated. Here we report the human glucocorticoid receptor (GR) Serine 134 as a novel target for p38 MAPK. Unlike most other phosphorylation events that occur on the GR, phosphorylation of Ser134 was found to be hormone-independent in several human and rat cell types. Instead we found phosphorylation of Ser134 was induced by a variety of stress-activating stimuli, including: glucose starvation, ultraviolet irradiation, osmotic shock, and oxidative stress. Pharmacological inhibitors and shRNA-mediated knockdown experiments correlate this phosphorylation with the activation of p38 MAPK. Compared to wild-type GR, cells expressing a mutant receptor incapable of phosphorylation at Ser134 (S134A GR) had a significantly altered hormone-dependent genome-wide transcriptional response to glucocorticoids. Moreover, we show that although WT GR regulated roughly half as many genes as S134A GR, WT receptor selectively activated significantly more genes associated with endocrine and inflammatory disease than the mutant receptor, suggesting that the phosphorylation status of Ser134 is critical for modulating GR function. Phosphorylation of Ser134 did not alter either nuclear translocation or the stability of the GR protein in the absence or presence of ligand. However, phosphorylation of Ser134 significantly increased the association of the GR with the zeta isoform the 14-3-3 class of signaling proteins, resulting in a blunted hormone-dependent transcriptional response of LAD1 and IGFBP1 but not GILZ. Together these data suggest that the phosphorylation of Ser134 acts as a molecular sensor on the GR, monitoring the level of cellular stress to allow for altered 14-3-3zeta cofactor association, ultimately modifying glucocorticoid signaling in a gene-dependent manner. Our results reveal one mechanism that may allow cellular stress to dictate the transcriptional response of cells to hormone. U2OS cells, a human osteosarcoma cell line, were transfected with either WT GR or S134A GR and put under antibiotic selection to produce a stable mixed population of cells expressing comparable levels of GR. 10^6 cells were treated with 100nM Dexamethasone (DEX) or vehicle control for 6 hours. Three biological and one hybridization replicate are included for each sample.

Dataset Information

Phosphorylation of Farnesoid X Receptor at Serine 154 Links Ligand Activation With Degradation.

Publications

Phosphorylation of Farnesoid X Receptor at Serine 154 Links Ligand Activation With Degradation.

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