THE REDOX-MEDIATED REGULATION OF IRON-RESPONSIVE GENE EXPRESSION IN LIVER

氧化还原介导的肝脏铁响应基因表达的调节

• 批准号: 7720824
• 负责人: Duygu Dee Dee Harrison-Findik
• 金额: $ 7.04万
• 依托单位: UNIVERSITY OF NEBRASKA LINCOLN
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7720824
• 关键词: Alcoholic Liver Diseases; Alcohols; Antioxidants; Apoptosis; CCAAT-Enhancer-Binding Protein-alpha; CEBPA gene; Carrier Proteins; Cell membrane; Chronic; Computer Retrieval of Information on Scientific Projects Database; DNA Binding; Diagnostic; Enzymes; Ethanol Metabolism; Funding; Gene Expression; Genetic Transcription; Grant; Hepatitis C; Hepatitis C virus; Hepatocyte; Homeostasis; Human; Injury to Liver; Institution; Intestines; Iron; Iron Overload; Iron-Regulatory Proteins; Knockout Mice; Lipid Peroxidation; Liver; Liver diseases; Mediating; Mediator of activation protein; Molecular; Mus; NADPH Oxidase; Oxidation-Reduction; Oxidative Stress; Patients; Peptides; Play; Process; Regulation; Regulator Genes; Research; Research Personnel; Resources; Role; Severities; Signal Transduction; Source; TNFRSF6 gene; Tumor Necrosis Factor Ligand Superfamily Member 6; United States National Institutes of Health; Virus Diseases; hepatoma cell; hepcidin; in vitro Model; in vivo; in vivo Model; macrophage; metal transporting protein 1; novel; novel therapeutics; promoter; tool

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Increases in oxidative stress correspond to the severity of liver diseases such as alcoholic liver disease (ALD) and hepatitis C. Patients with ALD or chronic hepatitus C virus infection frequently display iron overload. Iron acts synergistically with other agents (i.e. alcohol, hepatitis C virus) causing lipid peroxidation and oxidative stress, leading to liver injury. However, the underlying mechanisms of iron accumulation are unclear. In the last decade, novel iron-regulatory proteins, including soluble mediators and iron transporters, have been discovered. Hepcidin is a circulatory peptide synthesized in the liver. Hepcidin plays a key role in the regulation of iron homeostasis by regulating iron transport in the intestine and macrophages. Recently, we have demonstrated that alcohol-induced oxidative stress down-regulates hepcidin expression in the liver, which leads to an increased intestinal expression of the iron transporter protein, ferroportin, in vivo. This process was inhibited by injecting mice with antioxidants. In addition, our findings demonstrate that the redox changes and oxidative stress associated with alcohol metabolism also inhibit hepacidin promoter activity, and the DNA-binding activity of C/EBP alpha, which is known to regulate hepcidin transcription. It is noteworthy that hepcidin synthesis in the liver responds to body iron levels, and is up-regulated by iron overload in vivo. However, we have demonstrated that alcohol renders liver hepcidin synthesis insensitive to body iron levels. Collectively, these findings suggest that the mechanisms which protect the body from the harmful effects of iron overload (eg. increased hepcidin expression and decreased iron transport) are compromised by alcohol-mediated oxidative stress. Interestingly, CD95 (Apo1/Fas) ligand-mediated apoptosis also down-regulates liver hepcidin expression, which is inhibited by antioxidants in vivo. Furthermore, our preliminary results demonstrate a role for NADPH oxidase enzyme in the regulation of hepcidin expression in vivo. The aim of this project is to investigate the molecular mechanisms by which the redox signaling and plasma membrane-associated redox enzymes in the liver regulate the expression of iron-regulatory genes by alcohol and apoptosis in vivo. For these studies, we will employ mice, including NADPH oxidase knockout mice, as in vivo models, and primary mouse hepatocytes and human hepatoma cells as in vitro models. A better understanding of these mechanisms may help us to develop novel therapeutic strategies and diagnostic tools for liver diseases.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 氧化应激的增加与酒精性肝病 (ALD) 和丙型肝炎等肝脏疾病的严重程度相对应。患有 ALD 或慢性丙型肝炎病毒感染的患者经常表现出铁超负荷。 铁与其他物质（即酒精、丙型肝炎病毒）协同作用，导致脂质过氧化和氧化应激，导致肝损伤。 然而，铁积累的潜在机制尚不清楚。 在过去的十年中，人们发现了新型铁调节蛋白，包括可溶性介质和铁转运蛋白。 铁调素是一种在肝脏中合成的循环肽。 铁调素通过调节肠道和巨噬细胞中的铁转运，在铁稳态的调节中发挥关键作用。 最近，我们证明酒精诱导的氧化应激会下调肝脏中铁调素的表达，从而导致体内铁转运蛋白铁转运蛋白的肠道表达增加。 通过给小鼠注射抗氧化剂可以抑制这一过程。 此外，我们的研究结果表明，与酒精代谢相关的氧化还原变化和氧化应激也会抑制铁调素启动子活性，以及​​已知调节铁调素转录的 C/EBP α 的 DNA 结合活性。 值得注意的是，肝脏中铁调素的合成会对体内铁水平做出反应，并因体内铁超载而上调。 然而，我们已经证明，酒精会使肝脏铁调素的合成对体内铁水平不敏感。 总的来说，这些发现表明，保护身体免受铁超载有害影响的机制（例如铁调素表达增加和铁转运减少）受到酒精介导的氧化应激的损害。 有趣的是，CD95 (Apo1/Fas) 配体介导的细胞凋亡也会下调肝脏铁调素的表达，而肝铁调素的表达在体内受到抗氧化剂的抑制。 此外，我们的初步结果证明了 NADPH 氧化酶在体内铁调素表达调节中的作用。 该项目的目的是研究肝脏中氧化还原信号和质膜相关氧化还原酶通过酒精和体内细胞凋亡调节铁调节基因表达的分子机制。 在这些研究中，我们将使用小鼠（包括 NADPH 氧化酶敲除小鼠）作为体内模型，并使用原代小鼠肝细胞和人肝癌细胞作为体外模型。 更好地了解这些机制可能有助于我们开发新的肝病治疗策略和诊断工具。