The Mediator complex in the coordinate regulation of lipogenic gene expression

脂肪生成基因表达协调调节的介体复合体

基本信息

批准号：
9923643
负责人：
JEFFREY E. PESSIN
金额：
$ 59.43万
依托单位：
ALBERT EINSTEIN COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-06-15 至 2021-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9923643
关键词：
Binding Biological CREB1 gene Cancer cell line Catecholamine Receptors Centrifugation ChIP-seq Chromatin Complex Cultured Cells Cyclic AMP Cyclic AMP-Dependent Protein Kinases DNA Binding DNA Polymerase II DNA-Directed RNA Polymerase Data Diet Dissociation Drosophila genus FOXO1A gene FRAP1 gene Fasting GTP-Binding Proteins Gene Expression Gene Targeting Genes Genetic Genetic Transcription Glucagon Receptor Gluconeogenesis Glycerol HDAC3 gene Head Hepatic Hepatocyte Histones IRS1 gene Immunoblotting Individual Insulin Insulin Receptor Insulin Resistance Investigation Larva Literature Liver MED15 Mammalian Cell Mediating Mediator of activation protein Metabolic Molecular Morphologic artifacts NR0B1 gene Nuclear Receptors Nutrient Nutritional Pathologic Phosphorylation Phosphotransferases Physiological Production Protein Isoforms Proteins Regulation Reporting Research Personnel Rodent Model Role Signal Pathway Signal Transduction Structure Tail Thyroid Hormone Receptor Tissues Transcription Coactivator Ubiquitination Work XBP1 gene Yeasts base cofactor feeding genetic corepressor glucose output glucose production hormonal signals human model in vivo insulin regulation insulin signaling lipid biosynthesis migration mouse model protein expression transcription factor transcriptome sequencing ubiquitin-protein ligase

项目摘要

ABSTRACT In human and rodent models of insulin resistance, the regulation of gluconeogenesis is altered such that hepatic glucose production is enhanced in the fasted state with reduced suppression in the fed state. In parallel, hepatic de novo lipogenesis is elevated in fasted state and further increased in the fed state. The inability of insulin to suppress hepatic glucose output but still to activate de novo lipogenesis has been referred to as selective insulin resistance. Numerous studies have examined the regulation of DNA binding transcription factors, transcription factor co-activators and co-repressors in the control of liver lipogenic gene expression. Despite the intensive investigation of these trans-factors that control lipogenic gene expression, none of these proteins directly interacts with DNA-dependent RNA polymerase II and it has generally been believed that all of the regulation occurs at the level of the trans-factors. One critical complex termed the Mediator connects multiple trans-factors to the DNA-dependent RNA polymerase II. In mammalians, Mediator is composed of at least 30 individual subunits that are assembled from four sub-complexes, head, middle, tail and kinase sub-modules. In yeast, it was originally suggested that the Mediator is a constitutive component of the expression machinery. However, in drosophila larvae, hepatocyte cultured cells, and liver in vivo we recently demonstrated that the CDK8/CycC complex a component of the kinase sub-module (CDK8/CycC, Med12 and Med13) undergoes dynamic regulation by insulin and nutritional states. Based upon these previous and our new preliminary data that mTORC1 regulates the protein levels of Mediator kinase submodule (CDK8/CycC, MED12 and MED13), we hypothesize that the Mediator complex undergoes structural reorganization from a lipogenic transcriptional repressing state (so called large Mediator complex) in the fasted state to a lipogenic transcriptional activating state (so called small Mediator complex) in the fed state. The dysregulation of the Mediator complex in states of insulin resistance accounts, at least in part, for the elevation of lipogenic gene expression in the fasted state. In this proposal we will determine the physiologic and patho- physiologic alterations of the Mediator complex, the nutritional signals and their dysregulation resulting in the Mediator complex re-organization, and the consequences of these changes on lipogenic gene expression.

抽象的在人类和啮齿动物的胰岛素抵抗模型中，糖异生的调节发生了改变，使得肝葡萄糖生成在禁食状态下增强，而在进食状态下抑制减少。与此同时，肝脏从头脂肪生成在禁食状态下升高，并在进食状态下进一步增加。胰岛素无法抑制肝脏葡萄糖输出但仍不能激活从头脂肪生成，这被称为选择性胰岛素抵抗。许多研究已经检验了 DNA 结合转录因子、转录因子辅激活因子和辅抑制因子在控制肝脏脂肪生成基因表达中的调节作用。尽管对这些反式因子进行了深入研究控制脂肪生成基因表达的蛋白质，这些蛋白质都不直接与 DNA 依赖性 RNA 聚合酶 II 相互作用，并且通常认为所有调节都发生在反式因子水平。一种称为介体的关键复合物将多个反式因子连接到 DNA 依赖性 RNA 聚合酶 II。在哺乳动物中，Mediator 由至少 30 个单独的亚基组成，这些亚基由四个子复合体（头、中、尾和激酶子模块）组装而成。在酵母中，最初认为介体是表达机制的组成部分。然而，在果蝇幼虫、肝细胞培养细胞和体内肝脏中，我们最近证明了 CDK8/CycC 复合体是激酶子模块（CDK8/CycC、Med12 和 Med13）的组成部分，受到胰岛素和营养状态的动态调节。基于 mTORC1 调节介体激酶子模块（CDK8/CycC、MED12 和 MED13）的蛋白质水平的这些先前数据和我们新的初步数据，我们假设介体复合物从脂肪生成转录抑制状态（所谓的大介体复合物）经历结构重组。）从禁食状态到进食状态下的脂肪生成转录激活状态（所谓的小介体复合体）。胰岛素抵抗状态下介体复合物的失调至少部分解释了禁食状态下脂肪生成基因表达的升高。在本提案中，我们将确定生理和病理- 介体复合体的生理变化、营养信号及其失调导致介体复合体重组，以及这些变化对脂肪生成基因表达的影响。