MECHANISM OF ACTION OF ERYTHROFERRONE AND PATHOLOGICAL IMPLICATIONS

项目摘要 该建议旨在阐明正常和病理性红细胞生成发挥作用的机制， 对铁代谢和其他代谢过程的全身影响。促红细胞生成素激活红细胞生成 (EPO)导致铁调素的快速抑制，从而增加铁吸收和铁释放 从商店买的。我们发现红细胞铁酮（ERFE）是主要的激素，它是由成红细胞产生的激素 铁是一种调节剂，它使铁的供应与红细胞生成的不断变化的需求急剧匹配。提出了ERFE 与调节铁调素转录的骨形态发生蛋白（BMP）结合。在贫血症中 对于无效的红细胞生成，ERFE浓度增加不仅可能导致铁过载， 使无效的红细胞生成恶化，但也促进其它全身性表现。在本提案中，我们将 扩展ERFE作用机制的研究，定义ERFE靶向的BMP配体， 进行详细的结构-功能研究。此外，我们构建了转基因小鼠品系， 成红细胞中ERFE水平分级，并出现成比例的铁过载和其他全身性表现 贫血伴无效红细胞生成我们将使用这些小鼠来分析血液学和非- 过量ERFE的血液学后果。拟议项目的具体目标是： 1.表征ERFE生物活性的结构决定因素以及ERFE与BMP的相互作用。 我们将使用以下测定来确定鼠和人ERFE靶向的BMP家族的所有成员： 生物活性和直接物理相互作用。我们将定义ERFE的生物活性部分，并执行 ERFE生物活性所需的特定氨基酸的完整结构-功能分析。 2.分析体内ERFE浓度增加的血液学效应。小鼠模型中 分级ERFE过表达，我们将分析ERFE对铁负荷和红细胞生成的影响， 确定哪些作用不依赖于铁调素。为了研究高ERFE在β地中海贫血中的作用，我们 将ERFE转基因导入β-地中海贫血的th 3/+模型，并检查红细胞生成， 铁超载最后，我们将测试治疗性抗ERFE单克隆抗体逆转ERFE效应的能力。 3.阐明体内ERFE浓度增加的非血液学效应。利用转基因 ERFE小鼠，我们将确定ERFE对大脑，躯体生长，骨骼和脂肪组织的影响， 肾脏发育，所有这些都在我们的初步表征中受到影响。 成功完成拟议的研究将回答有关一个基本方面的长期问题 在人类和脊椎动物生物学中，铁的供应与不同的铁相匹配的机制 红细胞生成的要求。这项工作将为铁超载的发病机制提供重要的见解 在β-地中海贫血和其他具有无效红细胞生成的贫血中， 了解导致这些疾病的衰弱性全身效应的机制。

Project Summary This proposal aims to elucidate the mechanisms by which normal and pathological erythropoiesis exerts systemic effects on iron metabolism and other metabolic processes. Activation of erythropoiesis by erythropoietin (EPO) causes rapid suppression of hepcidin, with consequent increase in iron absorption and the release of iron from stores. We discovered erythroferrone (ERFE), a hormone produced by erythroblasts, as the principal mediator that acutely matches the iron supply to the changing requirements of erythropoiesis. ERFE is proposed to bind to and inactivate bone morphogenetic proteins (BMPs) that regulate hepcidin transcription. In anemias with ineffective erythropoiesis, increased ERFE concentrations may not only contribute to iron overload and worsen ineffective erythropoiesis but also promote other systemic manifestations. In this proposal, we will expand the study of the mechanism of action of ERFE, define the set of BMP ligands targeted by ERFE, and conduct a detailed structure-function study. Also, we constructed transgenic mouse lines that overexpress graded levels of ERFE in erythroblasts and develop proportional iron overload and other systemic manifestations of anemias with ineffective erythropoiesis. We will use these mice to analyze the hematological and non- hematological consequences of excessive ERFE. The specific aims of the proposed project are: 1. Characterize the structural determinants of ERFE bioactivity and the interaction of ERFE with BMPs. We will define all the members of the BMP family targeted by murine and human ERFE using assays for both bioactivity and direct physical interaction. We will define the bioactive segment of ERFE and perform complete structure-function analysis of the specific amino acids required for ERFE bioactivity. 2. Analyze the hematological effects of increased ERFE concentrations in vivo. In mouse models of graded ERFE overexpression, we will analyze the effect of ERFE on iron loading and erythropoiesis, and identify which effects are independent of hepcidin. To study the effects of high ERFE in β-thalassemia, we will introduce the ERFE transgene into the th3/+ model of β-thalassemia and examine erythropoiesis and iron overload. Finally, we will test the ability of a therapeutic anti-ERFE Mab to reverse the effects of ERFE. 3. Elucidate the nonhematological effects of increased ERFE concentrations in vivo. Using transgenic ERFE mice, we will define the effects of ERFE on the brain, somatic growth, bone and adipose tissues, and renal development, all of which were affected in our preliminary characterization. Successful completion of the proposed studies will answer longstanding questions about a fundamental aspect of human and vertebrate biology, the mechanism by which the supply of iron is matched to the varying iron requirements of erythropoiesis. The work will provide important insights into the pathogenesis of iron overload in β-thalassemia and other anemias with ineffective erythropoiesis, globally very common diseases, and enhance the understanding of the mechanisms that cause the debilitating systemic effects of these diseases.