GLUCOCORTICOID RECEPTOR POST-TRANSLATIONAL MODIFICATIONS IN INSULIN RESISTANCE

摘要： 代谢综合征是一种全球流行病，其特征是胰岛素抵抗、高血压和高血糖。 向心性肥胖虽然代谢综合征的病因学仍然是一个活跃的研究领域，但一个主要的研究领域是： 一种假说认为，它是由关键的胰岛素反应组织中糖皮质激素（GC）水平升高引起的， 肝脏和脂肪GC是由肾上腺产生的应激激素。GC与GC受体（GR）结合， 一种核激素受体，通过多种机制改变靶基因的转录，包括直接 与DNA结合（反式激活）以及蛋白质-蛋白质介导的阻遏。GC也是有效的 治疗许多炎性疾病，包括慢性阻塞性肺病、炎性 肠道疾病和类风湿性关节炎，但它们的使用是有限的，由于不利的代谢作用，包括 体重增加、胰岛素抵抗和高血压。最近，几个小组已经确定了GR后- 在细胞系中，GR的转录修饰（PTM）是一个重要的事件，并且这些PTM事件改变GR的转录活性。然而，在这方面， GRPTM在体内生理相关范例中的作用是未知的。根据初步数据，我 假设GR PTM，特别是磷酸化，介导GC对肝脏的复杂作用， vivo.这一假设将在三个具体目标进行测试：1）我们将确定GR磷酸化的作用， 对肝细胞代谢和基因表达的影响。这将通过添加回野生型或磷酸突变体来完成 2）我们将确定GR磷酸化在GR敲低肝癌细胞中的作用。 介导小鼠肝脏中的肝代谢、基因表达和GR占有。会来做这项工作 用GR抗体分析代谢、基因表达和染色质免疫沉淀。 使用CRISPRS创建新的GR敲入磷酸突变小鼠。这些S211 A小鼠有一把钥匙 磷酸化丝氨酸残基突变为丙氨酸。我们将确定哪种GC介导的肝脏变化， 脂质代谢、基因表达和GR占有是磷酸化依赖性的。3)我们将确定是否 GR磷酸化与肥胖患者样本中的肝脏胰岛素抵抗相关， Roux-en-Y胃旁路手术这将通过对这些患者的肝活检进行染色来完成（以及 对照）与磷酸GR特异性抗体。目前，正在开发选择性GR调节剂， 治疗代谢性疾病以及更安全的抗炎药物。因此了解 GR PTM在介导GC效应中的作用应该为代谢性疾病的新治疗提供线索， 以及常见的炎症。

Abstract: There is a global epidemic of metabolic syndrome, characterized by insulin resistance, hypertension, and central obesity. Although the etiology of metabolic syndrome is still an active area of investigation, one leading hypothesis is that it is caused by elevated glucocorticoid (GCs) levels in key insulin responsive tissues such as liver and fat. GCs are stress hormones produced by the adrenal gland. GCs bind to the GC receptor (GR) a nuclear hormone receptor that alters transcription of target genes by multiple mechanisms including direct binding to DNA (transactivation) as well as protein-protein mediated repression. GCs are also effective therapies for many inflammatory diseases including chronic obstructive pulmonary disease, inflammatory bowel disease and rheumatoid arthritis, but their use is limited due the adverse metabolic effects including weight gain, insulin resistance and hypertension. Recently, several groups have identified GR post- translational modification (PTM) in cell lines, and these PTM events alter GR transcriptional activity. However, the role of GR PTM in physiologically relevant paradigms in vivo is unknown. Based on preliminary data, I hypothesize that GR PTM, specifically phosphorylation, mediates the complex effects of GC on the liver in vivo. This hypothesis will be tested in three Specific Aims: 1) We will determine the role of GR phosphorylation on hepatocyte metabolism and gene expression. This will be done by adding back wildtype or phosphomutant GR isoforms to GR knockdown hepatoma cells 2) We will determine the role of GR phosphorylation in mediating heaptic metabolism, gene expression and GR occupancy in the livers of mice. This will be done by analyzing metabolism, gene expression and chromatin immunoprecipitation with antibodies to GR. We have created novel GR knockin phosphomutant mice using CRISPRS. These S211A mice have a key phosphorylated serine residue mutated to alanine. We will determine which GC mediated changes in hepatic lipid metabolism, gene expression and GR occupancy are phosphorylation dependent. 3) We will determine if GR phosphorylation is associated with hepatic insulin resistance in samples from obese patients undergoing Roux-en-Y gastic bypass surgery. This will be done by staining liver biopsies from these patients (as well as controls) with phosphoGR specific antibodies. Currently selective GR modulators are being developed for the treatment of metabolic diseases as well as safer anti-inflammatory medications. Therefore, understanding the role of GR PTM in mediating effects of GCs should shed light on novel treatments for metabolic disease as well as common inflammatory conditions.