Proopiomelanocortin Gene Expression and Obesity

阿黑皮质素原基因表达与肥胖

基本信息

批准号：
8639543
负责人：
MALCOLM James LOW
金额：
$ 34.63万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-08-01 至 2015-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8639543
关键词：
Acute Algorithms Alleles Anabolism Backcrossings Base Sequence Behavioral Binding Binding Sites Bioinformatics Biological Assay Body Composition Body Weight Body fat Brain Cardiovascular Diseases Cells Chronic Code Complex Conserved Sequence DNA Databases Dependency Developing Countries Diabetes Mellitus Diet Distal Elements Energy Intake Enhancers Epidemic Equilibrium Exons Expenditure FOS gene Fatty acid glycerol esters Food deprivation (experimental)Gene Expression Gene Expression Profile Genes Genetic Genetic Enhancer Element Genetic Transcription Genomic DNA Glucose Growth Health Homeodomain Proteins Hormonal Hypothalamic structure In Situ Hybridization In Vitro Inbreeding Indirect Calorimetry Individual Insulin Knowledge Label Leptin Longevity Measurement Measures Messenger RNA Metabolic Metabolic syndrome Molecular Motor Activity Mus Mutant Strains Mice Mutation Names Neurobiology Neurons Neuropeptides Neurosecretory Systems Nuclear Protein Nuclear Translocation Nucleus solitarius Obesity Oligonucleotide Probes Overweight Pathway interactions Peripheral Phenotype Phylogenetic Analysis Physiological Pituitary Gland Population Predisposition Prevention Pro-Opiomelanocortin Process Protein Precursors Public Health Reading Regulation Relative (related person)Reverse Transcriptase Polymerase Chain Reaction Role Signal Pathway Signal Transduction Site Structure of nucleus infundibularis hypothalami Testing Tissues Transactivation Transgenic Mice Western World Zebrafish base blood glucose regulation candidate selection chromatin immunoprecipitation comparative congenic design energy balance feeding gene function homeodomain in vivo insulin signaling mutant neural circuit novel obesity treatment promoter psychologic public health relevance relating to nervous system research study response transcription factor

项目摘要

DESCRIPTION (provided by applicant): One of the greatest current threats to health and lifespan in both the Western world and developing countries is overweight and obesity due to the predisposition for type-2DM, cardiovascular disease, and other manifestations of the metabolic syndrome. Body weight is normally maintained in a narrow range through a complex orchestration of hormonal, neural, and metabolic signals reciprocating between the brain and peripheral tissues. The obesity epidemic has emerged because of recent environmental, sociological, and genetic interactions that have unfavorably tipped the balance in favor of excess caloric storage as body fat. One critical component of the neural circuitry that regulates caloric intake and expenditure is the tiny population of neurons located in the hypothalamus and medulla that express the Pomc gene and synthesize the neuropeptides aMSH and bEndorphin from the precursor protein, proopiomelanocortin (POMC). In the current project period, we made significant progress towards explaining how transcription of Pomc is restricted to these specialized neurons, which are a primary portal to the brain for peripheral signals relating energy flux. We located a modular enhancer locus about 10 kb upstream of exon 1 that directs POMC neuron-specific gene expression and functions independently of pituitary-specific promoter elements. Closer bioinformatic and functional interrogation of this locus revealed two evolutionarily distinct modules within the Mammalian lineage that we named nPE1 and nPE2 for neuronal POMC Enhancer. Mutant strains of mice were generated that carry deletions of individual or both nPE elements (D1, D2, and D1D2). Our preliminary phenotypic analyses of these mice, and parallel strains with insertions of a PGK-neo selection cassette in the distal enhancer locus, led us to the hypotheses that nPE1 and nPE2 possess distinct, nonredundant control over Pomc expression in the brain, and moreover, that at least one additional neuronal enhancer for Pomc has yet to be identified. Core nucleotide sequence motifs within the enhancers and ongoing testing of candidate transcription factors suggest that a unique combination of homeodomain factors is responsible for POMC neuron-specific expression. Therefore, the specific aims for this project renewal are to: 1) Dissect the physiological roles of the Pomc neuronal enhancers nPE1 and nPE2 on the regulation of energy balance; 2) Analyze the interrelationships among neuroendocrine signaling pathways, cellular activation, and Pomc enhancer elements that regulate neuronal Pomc expression using the nPE mutant strains; 3) Unravel the neuronal Pomc transcriptional code through the identification of the entire set of enhancers and the essential motifs necessary to control Pomc expression in hypothalamic Arc neurons and the NTS; and 4) Identify the transcription factors responsible for cell-specific transactivation of the Pomc gene in the CNS. Completion of these aims will provide fundamental knowledge about an essential neurobiological control point for body mass and may point to new avenues for the prevention or treatment of obesity based on exploitation of the underlying molecular mechanisms.

描述（由申请人提供）：由于对2DM类型，心血管疾病的倾向以及代谢综合征的其他表现，西方世界和发展中国家对健康和寿命的最大威胁之一是超重和肥胖。通常，通过复杂的荷尔蒙，神经和代谢信号在大脑和外围组织之间的往复式互助的荷尔蒙，神经和代谢信号的编排，体重通常保持在狭窄的范围内。由于最近的环境，社会学和遗传相互作用，肥胖流行已经出现了，这些相互作用不利地平衡了平衡，而支持过量的热量储存作为体内脂肪。调节热量摄入和支出的神经回路的一个关键组成部分是位于下丘脑和延髓中的少量神经元，这些神经元表达了POMC基因并合成了前体蛋白（POMC）的神经肽AMSH和Bentorphin。在当前的项目期间，我们取得了重大进展，以解释POMC的转录如何仅限于这些专门的神经元，这些神经元是大脑的主要门户，用于与能量通量有关的外围信号。我们找到了外显子1上游约10 kb的模块化增强子基因座，该基因座是独立于垂体特异性启动子元素的指导POMC神经元特异性基因表达和功能。对该基因座进行的更紧密的生物信息学和功能询问揭示了哺乳动物谱系中的两个进化不同的模块，我们将NPE1和NPE2命名为NPE1和NPE2，用于神经元POMC增强子。产生的小鼠突变菌株是携带单个或两个NPE元素（D1，D2和D1D2）的缺失的。我们对这些小鼠的初步表型分析，以及在远端增强子基因座中插入PGK-NEO选择盒的平行菌株，这使我们提出了NPE1和NPE2的假设，即NPE1和NPE2在大脑中具有对POMC表达的非冗余，并且至少可以识别一个神经元增强剂，以识别POMC的表达。增强子内的核心核苷酸序列基序和候选转录因子的持续测试表明，同源域因子的独特组合是POMC神经元特异性表达的原因。因此，该项目更新的具体目的是：1）剖析POMC神经元增强剂NPE1和NPE2在能量平衡调节中的生理作用； 2）分析使用NPE突变菌株调节神经元POMC表达的神经内分泌信号通路，细胞激活和POMC增强子元件之间的相互关系； 3）通过识别整个增强子集的识别以及控制下丘脑弧神经元和NTS中POMC表达所必需的基本基序来揭示神经元POMC转录代码； 4）确定导致CNS中POMC基因细胞特异性反式激活的转录因子。这些目标的完成将提供有关体重的基本神经生物学控制点的基本知识，并可能指出基于对基本分子机制的开发，预防或治疗肥胖的新途径。