HRI/elF2aP Signaling Pathway as Potential Pharmaceutical Targets for Thalassemia

描述(由申请人提供)：我们这项拟议研究的长期目标是发现治疗红血球疾病合并血红蛋白病的新疗法。在这项提案中，我们将重点放在翻译调控在地中海贫血中的作用。地中海贫血是世界上最常见的单基因疾病，正在成为世界上主要的经济和健康负担。此外，在地中海贫血患者中，同样的珠蛋白基因突变可能会产生截然不同的临床结果，这是公认的，也是普遍注意到的。HEM调节的eIF21激酶(HRI)最初被发现可以抑制红系前体缺血症患者的一般蛋白质合成，从而平衡血红素和珠蛋白的合成。最近，我们实验室报道，不仅在缺铁性贫血中，而且在地中海贫血中，HRI都是必要的。事实上，到目前为止，HRI在地中海贫血小鼠模型中引起了最剧烈的修饰反应。HRI通过eIF2的磷酸化来调节这种保护。以及抑制蛋白质合成，包括？？珠蛋白，以防止？-珠蛋白聚集体的过度积累。因此，HRI及其下游底物可能成为开发治疗重型地中海贫血新疗法的潜在药物靶点。该建议的具体目的是(1)测试和评估Salubrine(一种专用于eIF2？p去磷酸化的小化学抑制剂)在减少Hbb-/？地中海贫血红系前体的珠蛋白聚集和凋亡方面的可行性；(2)筛选调节HRI应激反应通路和减少地中海贫血红系前体细胞凋亡的化合物文库。我们将使用HRI和主要珠蛋白基因缺乏的复合小鼠作为一种严重形式的地中海贫血的模型。我们将检测Salubrine是否能增加小鼠地中海贫血红细胞前体eIF2p水平，减少β-珠蛋白合成和聚集，减少增殖和凋亡。我们将使用亚砷酸盐诱导的细胞毒性作为地中海贫血的模型系统来筛选保护红系前体细胞存活的化学物质。候选化合物实现保护的分子机制是什么？？将对地中海贫血红系进行调查。这些研究的结果可能导致发现不仅治疗地中海贫血，而且普遍治疗红细胞疾病的新化合物。公共卫生相关性：这项拟议研究的目的是加深我们对血红蛋白突变引起的贫血的病理学的理解。这项研究还可能导致发现治疗红细胞疾病的新药物。

DESCRIPTION (provided by applicant): Our long-term objective of this proposed research is to discover novel treatments for red cell disorders with hemoglobinopathy. In this proposal, we focus our efforts on the role of translational regulation in ??thalassemia. Thalassemia is the most common monogenic disease in the world, and is emerging as a major economics and health burden in the world. In addition, it is well established and commonly noticed in ??thalassemic patients that the same mutation in ??globin gene may have drastically different clinical outcome. Hem-regulated eIF21 kinase (HRI) is initially discovered to inhibit general protein synthesis in heme-deficiency of erythroid precursors, and thus balances heme and globin synthesis. Recently, our laboratory has reported that HRI is necessary to reduce the severity not only in iron-deficiency anemia, but also in ??thalassemia. In fact, HRI elicits the most drastic modifier response in mouse models of ??thalassemia to date. HRI mediates this protection by phosphorylation of eIF2?? and inhibition of protein synthesis including ??globin to prevent excessive accumulation of ?-globin aggregates. Thus, HRI and its downstream substrates may be potential pharmaceutical targets for the development of novel treatments of severe thalassemia. The specific aims of this proposal are (1) to test and evaluate the feasibility of salubrinal, a small chemical inhibitor specific for dephosphorylation of eIF2?P, in reducing globin aggregation and apoptosis in Hbb-/- ??thalassemic erythroid precursors; and (2) to screen chemical libraries for compounds that modulate HRI stress response pathway and reduce apoptosis of ??thalassemic erythroid precursors. We will use our compounded mice with deficiencies in HRI and ??major globin genes as a model of a severe form of ??thalassemia. We will examine whether salubrinal can increase eIF2??P level, decrease ?-globin synthesis and aggregation, and reducing proliferation and apoptosis in mouse thalassemic red cell precursors. We will use arsenite induced cell toxicity as a model system for ??thalassemia to screen for chemicals that will protect the survival of erythroid precursors. The molecular mechanisms by which candidate compounds achieve the protection in ?? thalassemic erythroid will be investigated. The outcome of these studies may leads to discovery of novel compounds for treatments of not only thalassemia but also red cell disorders generally. PUBLIC HEALTH RELEVANCE: The purpose of this proposed research is to further our understanding of the pathology of anemia caused by mutations in hemoglobin. This study may also lead to the discovery of novel drug treatments for red blood cell diseases.