Regulation of mammalian iron homeostasis by iron and transferrin

项目总结(见说明)； 由于铁(Fe)相关的疾病在世界范围内普遍存在，了解铁的动态平衡对于了解人类健康至关重要。铁的动态平衡是由海普西丁调节的，海普西丁是一种主要来自肝脏的多肽，它抑制饮食中铁的吸收和巨噬细胞铁的循环。红细胞生成驱动力增加和铁超载分别抑制和刺激了海普西丁的表达。本K99/R00应用的第一个目的是确定转铁蛋白(Tf)对体内表达的海普西丁的影响。这一目标已经完成。K99期的研究表明，Tf是一种丰富的血清金属结合蛋白，是铁转运到骨髓中促进红细胞生成所必需的，它依赖于和不依赖于Tf在红细胞生成中的作用来调节海普西丁的表达。这些研究还表明，Tf对于铁超载刺激海普西丁的表达是必不可少的；这种刺激可能是通过增加红细胞生成动力而抑制海普西丁表达的不明因子的一个靶点。这项K99/R00应用的第二个目标将在Roo阶段完成，目的是识别细胞锰(Mn)和铁稳态之间的共性和差异，以此作为进一步剖析铁稳态的手段。我将确定铁、锰和其他金属饱和的转铁蛋白的途径，以及差异调节肝细胞基因表达的方式，并确定转铁蛋白是否在细胞铁和锰的外流中发挥作用。第三个目标，也将在Roo阶段完成，是确定细胞金属动态平衡所需的新因素。由于高锰对许多细胞系有毒害作用，我将利用shRNA和cDNA文库改变细胞的基因表达，筛选耐高锰的细胞，并通过54MN和55Fe转运试验鉴定感兴趣的突变系。从这两个目标出发，我将建立一个有别于我导师的独立焦点，即铁在血液疾病中的作用。这一建议反映了我在研究哺乳动物金属动态平衡及其与人类健康和疾病的关系方面的总体趋势，并将导致金属动态平衡的范例，从中可以设计出金属相关疾病的新治疗方法。

PROJECT SUMMARY (See instructions); As iron (Fe)-related disorders are prevalent world-wide, understanding Fe homeostasis is critical to understanding human health. Fe homeostasis is regulated by hepcidin, a largely liver-derived peptide that inhibits dietary Fe absorption and macrophage Fe recycling. Hepcidin expression Is inhibited and stimulated respectively by increased erythropoietic drive and Fe overload. The first objective of this K99/R00 application was to determine the effect of transferrin (TF) on hepcidin expression in vivo. This objective has been completed. Studies during the K99 phase demonstrated that TF, an abundant serum metal-binding protein essential for Fe delivery to bone marrow for erythropoiesis, regulates hepcidin expression dependently and Independently of TF's role In erythropoiesis. These studies also demonstrated that TF Is essential for the stimulation of hepcidin expression by Fe overload; this stimulation is a likely target ofthe unidentified factor that mediates suppression of hepcidin expression by increased erythropoietic drive. The second objective of this K99/R00 application, to be completed during the ROO phase, is to identify commonalities and divergences between cellular manganese (Mn) and Fe homeostasis as a means to further dissect Fe homeostasis. I will identify the means by which TF saturated with Fe, Mn and other metals similarly and differentially regulate hepatocyte gene expression and determine if TF plays a role In cellular Fe and Mn efflux. The third objective, also to be completed during the ROO phase, is to identify novel factors required for cellular metal homeostasis. As high Mn levels are toxic to many cell lines, I will alter cellular gene expression with shRNA and cDNA libraries, select for cells resistant to high Mn levels and Identify mutant lines of interest by 54Mn and 55Fe transport assays. From these two objectives, I will establish an Independent focus divergent from my mentor's, the role of Iron in hematologic disorders. This proposal reflects the overall trend in my research the study of mammalian metal homeostasis and its relation to human health and disease¿and will lead to a paradigm of metal homeostasis from which novel treatments for metal-related disorders can be designed.