Hemochromatosis - Epidemiology and Molecular Mechanisms

血色素沉着症 - 流行病学和分子机制

• 批准号: 7523956
• 负责人: Pauline L Lee
• 金额: $ 40.27万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-28 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7523956
• 关键词: Accounting; Affinity Chromatography; Amino Acids; Anemia; Animals; Biological Assay; Breeding; Chronic; DNA; Diet; EMSA; Endopeptidases; Environmental Risk Factor; Epigenetic Process; Gene Mutation; Generations; Genes; Genetic; Genetic Transcription; Hemochromatosis; Homeostasis; Inflammation; Inherited; Iron; Iron Overload; Liver; Modification; Molecular Epidemiology; Mus; Mutant Strains Mice; Mutation; Natural Selections; Nuclear Extract; Nucleotides; Pathway interactions; Patients; Penetrance; Peptide Hydrolases; Peptides; Perception; Phenotype; Production; Proteins; Public Health; Purpose; Regulation; Reporter; Role; Serum; Signal Pathway; Site; System; Techniques; Transcriptional Regulation; Weaning; absorption; base; experience; hepcidin; in vivo; insight; mouse model; mutant; progenitor; promoter; response; transcription factor

DESCRIPTION (provided by applicant): The purpose of this project is to better understand the regulation of iron homeostasis. Dysregulation of iron homeostasis results in iron overload or iron deficiency. The major regulator of iron homeostasis is the 25 amino acid peptide hepcidin. Hemochromatosis caused by genetic mutations in HFE, TfR2 and HJV is due primarily to dysregulation of hepcidin transcription. We have recently discovered that a serum protease encoded by the Tmprss6 gene is a potent downregulator of hepcidin. A robust transcriptional response to iron is only observed in intact animals. To understand normal transcriptional regulation of hepcidin by iron and also to gain insight into the roles of the products of the genes known to be involved in its regulation, we will investigate hepcidin transcription in liver, the primary site of synthesis in wildtype mice and mutant mice lacking these genes. In a two-pronged approach we will: 1) study nuclear extracts prepared from mice stimulated with iron; and 2) investigate the response of hepcidin promoter reporter constructs in an in vivo system that we have devised. Classical ex vivo techniques including EMSA, ChIP assays, DNA affinity purification and mass spectrophotometric identification will be employed to identify transcription factors in nuclear extracts. These studies will reveal which transcription factors are involved in the response to iron and how this response is modified in mutant animals. There is marked variability in the expression of the hemochromatosis phenotype in patients homozygous for the C282Y HFE mutation. Studies to date have failed to identify either genetic or environmental factors that account for any but a very small portion of the known variability. We will investigate, in mice, whether there is transgenerational epigenetic modification of iron absorption, based on the experience of prior generations with iron. Mice receiving iron-deficient diets or diets containing iron excess will be bred and their offspring will either be weaned to the same diet or to a normal diet. Those weaned to a deficient or iron excess diet will be bred for additional generations. If transgenerational epigenetic modification occurs, then the iron burden of iron deficient mice moved to normal diet will be greater than that of mice derived from iron-heavy progenitors. PUBLIC HEALTH RELEVANCE: By studying various mouse models of iron overload and iron deficiency, we will gain an understanding how the body regulates iron. This will open the door to treatments of iron overload, the anemia of chronic inflammation, as well as of hemochromatosis itself. If we are able to demonstrate that the regulation of iron absorption is inherited epigenetically, this finding would not only explain the variable penetrance of hemochromatosis, but would greatly alter our perception of how natural selection functions over the span of only a few generations.

描述（由申请人提供）：本项目的目的是更好地了解铁稳态的调节。铁稳态失调导致铁过载或铁缺乏。铁稳态的主要调节剂是25个氨基酸的肽铁调素。由HFE、TfR 2和HJV中的基因突变引起的血色素沉着症主要是由于铁调素转录的失调。我们最近发现由Tmprss 6基因编码的血清蛋白酶是铁调素的有效下调因子。一个强大的转录反应，铁只观察到在完整的动物。为了了解铁调素的正常转录调控，也为了深入了解已知参与其调节的基因的产物的作用，我们将研究铁调素在肝脏中的转录，野生型小鼠和缺乏这些基因的突变小鼠的主要合成位点。在一个双管齐下的方法中，我们将：1）研究从铁刺激的小鼠制备的核提取物; 2）研究铁调素启动子报告构建体在我们设计的体内系统中的反应。经典的离体技术，包括EMSA，ChIP测定，DNA亲和纯化和质谱鉴定将用于鉴定核提取物中的转录因子。这些研究将揭示哪些转录因子参与了对铁的反应，以及这种反应在突变动物中是如何改变的。在C282 Y HFE突变纯合子患者中，血色素沉着症表型的表达存在显著的变异性。迄今为止的研究未能确定任何遗传或环境因素，但已知的变异性的一小部分。我们将调查，在小鼠中，是否有铁吸收的跨代表观遗传修饰，根据前几代铁的经验。将饲养接受缺铁饮食或含铁过量饮食的小鼠，并将其后代断奶至相同饮食或正常饮食。那些断奶缺铁或铁过量的饮食将繁殖更多的几代人。如果发生跨代表观遗传修饰，那么转向正常饮食的缺铁小鼠的铁负荷将大于来自铁重祖细胞的小鼠。公共卫生关系：通过研究各种铁超载和铁缺乏的小鼠模型，我们将了解身体如何调节铁。这将为治疗铁超载、慢性炎症性贫血以及血色病本身打开大门。如果我们能够证明铁吸收的调节是表观遗传的，这一发现不仅可以解释血色素沉着症的变异率，而且可以大大改变我们对自然选择如何在短短几代人的时间内发挥作用的看法。