Regulation of Iron Homeostasis by BMP Signaling

BMP 信号传导对铁稳态的调节

基本信息

批准号：
8500252
负责人：
JODIE L BABITT
金额：
$ 34.78万
依托单位：
MASSACHUSETTS GENERAL HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-01 至 2015-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8500252
关键词：
Affect Amino Acids Anemia Anemia due to Chronic Disorder BMP6 gene BMP7 gene Binding Biochemical Biological Assay Blood Bone Morphogenetic Proteins Cell Culture System Cell Culture Techniques Cell surface Chelating Agents Co-Immunoprecipitations Complex Cycloheximide Dactinomycin Data Deposition Diet Dietary Iron Disease Dominant-Negative Mutation Elements Equilibrium Functional disorder Genes Genetic Genetic Transcription Genets Goals Growth Hemochromatosis Hepatic Hepatocyte Hereditary hemochromatosis Homeostasis Hormones Immunofluorescence Microscopy In Situ Hybridization In Vitro Intestines Iron Iron Metabolism Disorders Iron Overload Iron-Regulatory Proteins Knockout Mice Lead Ligands Liver Luciferases Mediating Messenger RNA Modeling Molecular Mus Mutation Nature Paper Pathway interactions Phenotype Play Post-Transcriptional Regulation Protein Biosynthesis Proteins Public Health Publishing Regulation Regulatory Pathway Relative (related person)Reporter Resistance Reverse Transcriptase Polymerase Chain Reaction Role Signal Pathway Signal Transduction Spleen Testing Time Tissues Toxic effect Transgenes Transgenic Mice Western Blotting Wild Type Mouse Work absorption bone morphogenetic protein receptors cell type ferric ammonium citrate hepcidin holotransferrin in vivo inhibitor/antagonist iron deficiency iron metabolism laser capture microdissection liquid chromatography mass spectrometry mRNA Expression metal transporting protein 1 novel novel therapeutics overexpression peptide hormone prevent promoter protein expression public health relevance receptor response transferrin receptor 2 treatment strategy

项目摘要

DESCRIPTION (provided by applicant): Iron homeostasis is tightly regulated to provide this critical element for growth and survival, but to prevent the toxicity of iron excess. We have recently discovered that the bone morphogenetic protein (BMP) signaling pathway plays an important role in systemic iron balance by modulating expression of the iron regulatory hormone hepcidin. A soluble protein secreted by the liver, hepcidin acts by downregulating the cell- surface expression of the iron exporter ferroportin to control iron absorption from the diet and iron release from body stores. Hepcidin deficiency, which causes excessive dietary iron absorption and progressive tissue iron deposition and dysfunction, appears to be the common pathogenic mechanism underlying the iron overload disorder hereditary hemochromatosis due to mutations in the genes encoding hepcidin itself, the hemochromatosis protein HFE, transferrin receptor 2, and hemojuvelin (HJV). Although the mechanism(s) by which HFE and transferrin receptor 2 regulate hepcidin expression remain uncertain, we have recently discovered that HJV is a BMP co-receptor and that BMP-HJV-SMAD signals regulate hepcidin expression and systemic iron balance in vivo. Here, we show that HJV binds BMP6, and that Bmp6-/- mice have a hemochromatosis phenotype resembling Hjv-/- mice, suggesting that BMP6 a key endogenous ligand for HJV that is necessary for regulating hepcidin expression and iron metabolism in vivo. We also show that dietary iron modulates BMP6 expression concordantly with hepcidin expression, suggesting that regulation of BMP6 expression may be one mechanism by which iron modulates hepcidin expression. Finally, we show that Hfe-/- mice have appropriately increased Bmp6 levels, but inappropriately low expression of downstream signaling targets of Bmp6, suggesting that HFE may interact with the BMP6-HJV-SMAD signaling cascade to regulate hepcidin expression. In Specific Aim I, we will use in vitro and in vivo approaches to determine the mechanism by which iron upregulates BMP6 expression. In Aim II, we will use iodinated protein-interaction and Biacore binding assays to dissect the protein-interaction domains that allow BMP6 and its co-receptor HJV to interact to enhance SMAD signaling and hepcidin expression. In Aim III, we will use biochemical assays, cell culture models, Hfe-/- mice, and Hfe transgenic mice to investigate whether HFE interacts with the BMP6-HJV-SMAD signaling cascade to regulate hepcidin expression. The long-term goal of this project is to understand the role of the BMP signaling pathway in regulating systemic iron homeostasis. It is hoped that this work may lead to new therapeutic strategies for treating disorders of iron metabolism such as anemia of chronic disease and hemochromatosis.

描述（由申请人提供）：铁稳态受到严格调节，以提供生长和生存的关键元素，但要防止铁过量的毒性。我们最近发现骨形态发生蛋白（BMP）信号通路通过调节铁调节激素铁调素的表达在全身铁平衡中发挥重要作用。铁调素是一种由肝脏分泌的可溶性蛋白质，通过下调铁输出蛋白铁转运蛋白的细胞表面表达来控制饮食中铁的吸收和身体储存中铁的释放。铁调素缺乏症会导致膳食铁吸收过多以及进行性组织铁沉积和功能障碍，这似乎是铁调素本身编码基因、血色沉着症蛋白 HFE、转铁蛋白受体 2、和血幼素（HJV）。尽管HFE和转铁蛋白受体2调节hepcidin表达的机制仍不清楚，但我们最近发现HJV是BMP共受体，并且BMP-HJV-SMAD信号调节hepcidin表达和体内全身铁平衡。在这里，我们表明 HJV 结合 BMP6，并且 Bmp6-/- 小鼠具有类似于 Hjv-/- 小鼠的血色素沉着症表型，这表明 BMP6 是 HJV 的关键内源配体，对于调节体内铁调素表达和铁代谢是必需的。我们还表明，膳食铁调节 BMP6 表达与铁调素表达一致，表明调节 BMP6 表达可能是铁调节铁调素表达的机制之一。最后，我们发现Hfe-/-小鼠的Bmp6水平适当升高，但Bmp6下游信号靶点的表达不适当地低，这表明HFE可能与BMP6-HJV-SMAD信号级联相互作用以调节铁调素表达。在具体目标 I 中，我们将使用体外和体内方法来确定铁上调 BMP6 表达的机制。在 Aim II 中，我们将使用碘化蛋白相互作用和 Biacore 结合测定来剖析允许 BMP6 及其共受体 HJV 相互作用以增强 SMAD 信号传导和铁调素表达的蛋白相互作用结构域。在目标 III 中，我们将使用生化测定、细胞培养模型、Hfe-/- 小鼠和 Hfe 转基因小鼠来研究 HFE 是否与 BMP6-HJV-SMAD 信号级联相互作用来调节铁调素表达。该项目的长期目标是了解 BMP 信号通路在调节全身铁稳态中的作用。希望这项工作能够为治疗铁代谢紊乱（例如慢性病贫血和血色素沉着症）带来新的治疗策略。