Institute for Molecular Bioscience, The University of Queensland, Services Rd, St Lucia, Queensland 4072, Australia.
Mol Cell Endocrinol. 2010 Feb 5;315(1-2):146-52. doi: 10.1016/j.mce.2009.07.012. Epub 2009 Jul 23.
Estrogen-related receptors (ERRs) are constitutively active orphan nuclear receptors. Natural ligands have not been identified, however, recent reports have demonstrated the synthetic phenolic acyl hydrazone, GSK4716, functions as a selective ERRbeta/gamma agonist. We demonstrate that ERRbeta is transiently induced, and ERRgamma is dramatically induced (and accumulates) in a differentiation-dependent manner in skeletal muscle cells. Treatment of differentiated skeletal muscle cells with the ERRbeta/gamma agonist (GSK4716) produced a significant increase in the expression of GRalpha (isoform D) protein. Quantitative RT-PCR (Q-RT-PCR) analysis after treatment with GSK4716, revealed induction of the mRNAs encoding the glucocorticoid receptor (GR), 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), the enzyme that converts inactive cortisone to cortisol and hexose-6-phosphate dehydrogenase expression (H6PDH) that stimulates oxoreduction by 11beta-HSD1. Candidate based expression profiling also demonstrated the mRNAs encoding characterized GR target genes, including C/EBP, ApoD and Monoamine oxidase-A (MAO-A) are induced in GSK4716 treated cells. In concordance with these observations, siRNA-mediated suppression of the mRNA encoding ERRgamma (but not ERRalpha and beta) attenuated the expression of mRNAs encoding GR, 11betaHSD1 and GR target gene(s). Similarly, treatment with the ERRgamma (and ERalpha) antagonist diethylstilbestrol (DES) suppressed glucocorticoid responsive gene expression in skeletal muscle cells. Interestingly, we observed that GSK4716 trans-activated GRE-TK-LUC in a GR-dependent manner. This study highlights the regulatory crosstalk between ERRgamma and GR signaling in skeletal muscle cells, and suggests the ERRgamma agonist modulates the expression of critical genes that control GR signaling and glucocorticoid sensitive gene expression.
雌激素相关受体（ERRs）是组成型激活的孤儿核受体。尽管尚未鉴定出天然配体，但最近的报告表明，合成的酚酰腙 GSK4716 可作为选择性 ERRβ/γ激动剂发挥作用。我们证明 ERRβ 是瞬时诱导的，而 ERRγ 则以分化依赖性方式显著诱导（并积累）。用 ERRβ/γ激动剂（GSK4716）处理分化的骨骼肌细胞会导致 GRα（同工型 D）蛋白的表达显著增加。用 GSK4716 处理后的定量 RT-PCR（Q-RT-PCR）分析显示，编码糖皮质激素受体（GR）、11β-羟类固醇脱氢酶 1 型（11β-HSD1）、将无活性可的松转化为皮质醇的酶和己糖-6-磷酸脱氢酶表达（H6PDH）的 mRNA 被诱导，这刺激了 11β-HSD1 的氧化还原反应。基于候选物的表达谱分析还表明，编码具有特征性 GR 靶基因的 mRNAs 包括 C/EBP、ApoD 和单胺氧化酶-A（MAO-A）在 GSK4716 处理的细胞中被诱导。与这些观察结果一致，siRNA 介导的 ERRγ（而不是 ERRα 和β）mRNA 抑制减弱了编码 GR、11β-HSD1 和 GR 靶基因的 mRNAs 的表达。同样，用 ERRγ（和 ERα）拮抗剂己烯雌酚（DES）处理也抑制了骨骼肌细胞中糖皮质激素反应基因的表达。有趣的是，我们观察到 GSK4716 以 GR 依赖性方式转激活 GRE-TK-LUC。这项研究强调了 ERRγ 和 GR 信号在骨骼肌细胞中的调节串扰，并表明 ERRγ 激动剂调节控制 GR 信号和糖皮质激素敏感基因表达的关键基因的表达。
