Molecular and Biological Activities of Alpha Hemoglobin Stabilizing Protein

描述（由申请人提供）：我们的研究解决了血红蛋白（Hb）生物学中的一个关键问题：在正常和病理红细胞生成过程中，固有不稳定的球蛋白亚基是如何折叠和维持的。我们发现了α血红蛋白稳定蛋白（AHSP），这是一种特异性结合游离？珠蛋白亚基，稳定其结构并限制其促氧化活性。我们的初步研究表明AHSP有两种不同的功能。第一，排毒过量？在正常红细胞生成和各种贫血中积聚的珠蛋白，特别是？地中海贫血。第二，折叠和稳定新形成的？球蛋白亚基在去往HbA （?2?? ?）2)合成。对于这两种功能的潜在重要性，我们发现铁可以加速AHSP mRNA的降解，铁是HbA的重要成分，也是新生球蛋白稳定性的决定因素。我们的总体观点是，AHSP促进正常的HbA合成，并缓冲由遗传或环境压力引起的失衡，如地中海贫血和缺铁。现在我们寻求更好地了解AHSP活动及其与人类健康的关系。目的1利用小鼠遗传学研究AHSP在体内的功能。我们将研究在地中海贫血中操纵AHSP表达的后果，并在小鼠中创建AHSP基因错义突变，以探索AHSP蛋白功能的机制。目的2研究AHSP的生化特性。我们将在体外测试AHSP是否能从其纯化的载脂蛋白和血红素成分中促进HbA的重建，并寻找与？globin-AHSP复合物。目的3探讨了铁调节AHSP表达的机制，以及在铁稳态改变过程中这一途径的生理意义。如果成功，我们的工作将建立新的血红蛋白生物学和红细胞生成的基本原理。此外，还有潜在的实际长期效益。例如，了解AHSP是如何排毒的？Hb应该说明新的人类治疗方法？地中海贫血。阐明AHSP在HbA合成中的作用可能为优化重组hb基血液代用品的制造提供工具。最后，确定铁和AHSP之间的功能相互作用可以为铁过载和缺铁状态的病理生理学和管理提供见解。项目描述：我们的工作是研究血氧载体血红蛋白在红细胞形成过程中是如何稳定和组装的。如果实验成功，我们的实验将提高人们对血液形成的普遍认识。此外，我们将为理解和治疗地中海贫血和缺铁等常见和衰弱性贫血提供新的见解。

DESCRIPTION (provided by applicant): Our studies address a critical problem in hemoglobin (Hb) biology: how inherently unstable globin protein subunits are folded and maintained during normal and pathological erythropoiesis. We discovered alpha hemoglobin stabilizing protein (AHSP), an erythroid protein that specifically binds free ? globin subunit, stabilizes its structure and limits its pro-oxidant activities. Our preliminary studies suggest two distinct functions for AHSP. First, to detoxify excess ? globin that accumulates during normal erythropoiesis and in various anemias, particularly ? thalassemia. Second, to fold and stabilize newly formed ? globin subunits en route to HbA (?2??2) synthesis. Of potential importance to both functions, we discovered that degradation of AHSP mRNA is accelerated by iron, an essential component of HbA and determinant of nascent globin protein stability. Our overall view is that AHSP facilitates normal HbA synthesis and also buffers against imbalances that arise from genetic or environmental stresses, such as thalassemias and iron deficiency. Now we seek to better understand AHSP activities and their relevance to human health. Aim 1 uses mouse genetics to investigate AHSP functions in vivo. We will examine the consequences of manipulated AHSP expression in thalassemias and create Ahsp gene missense mutations in mice to probe mechanisms of AHSP protein function. Aim 2 studies the biochemical properties of AHSP. We will test in vitro if AHSP promotes reconstitution of HbA from its purified apo-globin and heme components and search for new erythroid proteins that interact with ? globin-AHSP complexes. Aim 3 examines the mechanisms by which iron regulates AHSP expression and the physiological implications of this pathway during altered iron homeostasis. If successful, our work will establish new basic principles of Hb biology and erythropoiesis. In addition, there are potential practical long-term benefits. For example, understanding how AHSP detoxifies excess ?Hb should illustrate novel therapeutic approaches for human ? thalassemias. Elucidating the role of AHSP in HbA synthesis may provide tools to optimize the manufacture of recombinant Hb-based blood substitutes. Finally, defining functional interactions between iron and AHSP could provide insights into the pathophysiology and management of iron overload and deficiency states. PUBLIC HEALTH RELEVANCE: Project Narrative: Our work examines how the blood oxygen carrier hemoglobin is stabilized and assembled during red blood cell formation. If successful, our experiments will enhance general knowledge about how blood is formed. In addition, we will provide new insights toward understanding and treating common and debilitating anemias such as thalassemia and iron deficiency.