Molecular and Biological Activities of Alpha Hemoglobin Stabilizing Protein

描述(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：在正常和病理性红细胞生成过程中，天生不稳定的珠蛋白亚基是如何折叠和保持的。我们发现了α-血红蛋白稳定蛋白(AHSP)，这是一种红系蛋白，能特异性地结合FREE？珠蛋白亚基，稳定其结构，限制其促氧化活性。我们的初步研究表明，AHSP具有两种不同的功能。首先，排毒吗？尤其是在正常的红细胞生成过程中和在各种贫血中积累的珠蛋白？地中海贫血。第二，对新组建的企业进行折叠和稳定？珠蛋白亚基正在合成HBA(？2？？2)的途中。对于这两种功能的潜在重要性，我们发现AHSP mRNA的降解被铁加速，铁是HBA的基本成分，也是新生珠蛋白稳定性的决定因素。我们的总体观点是，AHSP促进了正常的HBA合成，也缓冲了由遗传或环境压力引起的失衡，如地中海贫血和缺铁。现在，我们试图更好地了解AHSP活动及其与人类健康的相关性。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，并在小鼠中创造AHSP基因错义突变，以探索AHSP蛋白功能的机制。目的研究AHSP的生化性质。我们将在体外测试AHSP是否促进其纯化的脱珠蛋白和血红素成分重建HBA，并寻找新的与？珠蛋白-AHSP复合体。目的3研究铁调节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乙肝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利益。例如，了解AHSP如何解毒？Hb应该说明人类的新治疗方法？地中海贫血。阐明AHSP在HBA合成中的作用可能为优化基于Hb的重组血液替代品的生产提供工具。最后，明确铁和AHSP之间的功能相互作用可以为铁超载和缺铁状态的病理生理学和管理提供见解。公共卫生相关性：项目叙述：我们的工作考察了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。如果成功，我们的实验将增强关于血液如何形成的一般知识。此外，我们还将为理解和治疗地中海贫血和缺铁性贫血等常见和衰弱的贫血提供新的见解。

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.