Iron Catalyzed H2S and its Prevalence in Hemolytic and Iron Overload Disorders

项目摘要/摘要 铁是参与细胞呼吸的氧化还原反应所必需的元素，大分子 合成和异种生物解毒。在哺乳动物中，它的主要作用是产生红细胞(RBC)。 以及氧气在全身的转移。尽管铁需要维持生命，但它的高活性 自然催化产生有害的活性氧和代谢物物种(ROMS)是必要的 其封存和利用活动的机制。这主要是通过绑定 红细胞和组织中铁转化为血红素、血红蛋白和铁蛋白。然而，在像镰刀这样的血液病中 细胞性贫血、溶血性危象和血色素沉着症时，游离铁的释放和超负荷增加。 铁超载导致心血管组织和其他外周器官的ROM值增加 与这些血液疾病有关。目前通过金属靶向铁蓄积的临床治疗 螯合或取血/输血的结果好坏参半，并伴随着临床后果。 因此，更好地表征和控制血液中铁催化的反应仍然是一个挑战 开辟治疗铁相关血液病的途径。美国国立卫生研究院血液学的新方向 研究(SIRE-II)建议，我们通过生化、代谢、蛋白质和营养来解决这些问题 方法和创新。我们把这些方法集中在我的实验室最近进行的一个化学反应上 发现其中硫化氢(H_2S)气体是由铁和维生素B6协调催化产生的 生理条件下的半胱氨酸。就像铁一样，硫化氢起着有益和有害的生理作用。 全身受剂量、暴露途径和组织特异性的影响。铁的作用 催化硫化氢在预防或促进血液系统疾病方面的作用尚不清楚。在这里，我们将测试 假设血液中铁催化的H_2S是一种可修饰的因素，导致或进展 血液病、镰状细胞性贫血和血色素沉着症。为了验证这一假设，我们将进行一个 目的并测定铁在体外和体内催化产生H_2S的机理和能力 来自溶血性贫血和铁超载模型的血液。为了实现这一目标，我们将1)雇用 选择性和灵敏的硫化氢和巯基检测技术，以探索生化机制， 体外和体外血液和组织中铁催化的硫化氢的需求、下游信号转导和2) 以含硫氨基酸和维生素B6为基础的饮食干预，作为预防或减缓的一种手段 体内与镰状细胞溶血危象相关的病理通过调节内源性硫化氢的产生。 利用这些方法来研究这种新的化学物质将突出铁的重要性 在血液中催化硫化氢的产生，以及控制它在血液疾病中的治疗潜力。

PROJECT SUMMARY/ABSTRACT Iron is an essential element required for redox reactions involved in cellular respiration, macromolecular synthesis, and xenobiotic detoxification. In mammals, its major role is in the production of red blood cells (RBCs) and transferring of oxygen throughout the body. Despite the life sustaining requirement of iron, its highly reactive nature to catalyze the production of damaging reactive oxygen and metabolite species (ROMS) necessitates mechanisms for its sequestration and harnessing of activity. This is primarily achieved through the binding of iron to heme, hemoglobin, and ferritin in RBCs and tissues. However, in hematological disorders such as sickle cell anemia, lytic crisis, and hemochromatosis, there is an increase in unbound iron release and overload. Increased ROMS by iron overload drive pathologies in cardiovascular tissues and other peripheral organs associated with these hematological disorders. Current clinical therapies targeting iron accumulation via metal chelation or blood removal/transfusions have been met with mixed results and come with clinical consequences. Thus, better characterizing and controlling iron catalyzed reactions in the blood remain as challenges as well as open avenues for treating iron-related hematological diseases. In this NIH New Directions in Hematological Research (SHINE-II) proposal, we address these issues via biochemical, metabolomic, proteomic, and nutritional approaches and innovations. We focus these methodologies on a chemical reaction my lab has recently uncovered in which hydrogen sulfide (H2S) gas is produced by an iron- and vitamin B6- coordinated catalysis of cysteine under physiological conditions. Much like iron, H2S serves beneficial and detrimental physiological roles throughout the body which are governed by dose, exposure route, and tissue specificity. The role of iron catalyzed H2S in prevention or promotion of hematological disorders is unknown. Here, we will test the hypothesis that iron catalyzed H2S in the blood is a modifiable factor in the initiation or progression of the blood disorders sickle cell anemia and hemochromatosis. To test this hypothesis, we will pursue one central AIM and determine the mechanism and capacities for H2S production catalyzed by iron in vitro and in blood derived from models of hemolytic anemia and iron-overload. To accomplish this aim, we will 1) Employ selective and sensitive H2S and sulfhydryl detecting techniques to explore the biochemical mechanisms, requirements, and downstream signaling of iron-catalyzed H2S in vitro and in blood and tissues ex vivo, and 2) Apply sulfur amino acid and vitamin B6 based dietary interventions as a means of preventing or slowing pathologies associated with sickle cell hemolytic crisis in vivo via modulating endogenous H2S production. Utilization of these approaches to investigate this novel chemistry will underscore the significance of iron catalyzed H2S production in the blood and the therapeutic potential of controlling it in hematological diseases.