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

项目概要/摘要 铁是参与细胞呼吸、大分子生物学和生物化学的氧化还原反应所需的必需元素。 合成和异生物质解毒。在哺乳动物中，它的主要作用是产生红细胞（RBC） 并将氧气输送到全身。尽管铁是维持生命的必需品，但它的高活性 催化有害活性氧和代谢物（ROMS）的产生的性质需要 其封存和利用活动的机制。这主要是通过以下方式实现的： 红细胞和组织中的铁转化为血红素、血红蛋白和铁蛋白。然而，在血液系统疾病，如镰刀， 细胞性贫血、溶解性危象和血色素沉着症时，游离铁释放和超负荷增加。 心血管组织和其他外周器官中铁过载驱动病理导致的ROMS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疗法 螯合或血液去除/输血已经遇到了混合的结果，并带来了临床后果。 因此，更好地表征和控制血液中的铁催化反应仍然是挑战， 为治疗与铁有关的血液病开辟了途径。在这个NIH血液学新方向 研究（SHINE-II）的建议，我们通过生物化学，代谢组学，蛋白质组学和营养学来解决这些问题 方法和创新。我们把这些方法集中在我的实验室最近 其中硫化氢（H2S）气体是通过铁和维生素B6配位催化产生的， 生理条件下的半胱氨酸。与铁非常相似，H2S具有有益和有害的生理作用 这取决于剂量、暴露途径和组织特异性。铁的作用 催化的H2S在预防或促进血液学病症中的作用是未知的。在这里，我们将测试 假设铁催化H2S在血液中是一个可修改的因素，在启动或进展， 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 中心AIM和确定机制和能力，为H2S生产催化铁在体外和体内 来自溶血性贫血和铁超负荷模型的血液。为了实现这一目标，我们将：（1） 选择性和灵敏的H2S和巯基检测技术，以探索生化机制， 体外和离体血液和组织中铁催化的H2S的下游信号传导，以及2） 应用含硫氨基酸和维生素B6为基础的饮食干预措施，作为预防或减缓 通过调节内源性H2S产生与体内镰状细胞溶血危象相关的病理学。 利用这些方法来研究这种新的化学将强调铁的重要性 催化血液中H2S的产生以及控制血液疾病中H2S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.