Novel Determinants of Terminal Erythroid Maturation

红细胞终末成熟的新决定因素

• 批准号: 8550827
• 负责人: Emery H Bresnick
• 金额: $ 38万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-26 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8550827
• 关键词: 1-Phosphatidylinositol 3-Kinase; AKT Signaling Pathway; Address; Anemia; Autophagocytosis; Autophagosome; Biological; Blood; Cell Cycle; Cell Differentiation process; Cell Maturation; Cell physiology; Cells; Chromatin; Clinical; Consumption; Cytoplasm; Development; Disease; Ensure; Erythroblasts; Erythrocytes; Erythroid; Erythroid Cells; Erythropoiesis; Functional disorder; Gene Activation; Gene Expression; Genes; Genetic; Hematopoietic; Higher Order Chromatin Structure; Human Genome; Longevity; Maintenance; Mediating; Mitochondria; Modeling; Molecular; Mus; Organelles; Oxidative Stress; Pathway interactions; Phosphorylation; Physiological; Polycythemia Vera; Process; Protein-Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Regulation; Signal Transduction; Site; Staging; Stem cells; Stress; System; Testing; Thalassemia; Therapeutic; Transfusion; abstracting; base; chromatin modification; feeding; human FRAP1 protein; human GATA1 protein; improved; in vivo; insight; mTOR inhibition; mouse genome; novel; stem; transcription factor

DESCRIPTION (provided by applicant): Elucidating mechanisms that regulate erythroid cell maturation is critical for devising targeted therapies for red cell disorders including thalassemias, polycythemia vera and anemias, and for developing strategies to generate red blood cells for clinical transfusion. The PI3-kinase-AKT pathway promotes and suppresses erythroid maturation. The inhibitory mechanism involves AKT-mediated phosphorylation of FoxO3, which leads to its sequestration in the cytoplasm. FoxO3 is upregulated/activated during erythroid maturation and by oxidative stress and controls the erythroid cell cycle and maturation, red blood cell lifespan, and protects against oxidative stress. We developed evidence that the serine/threonine kinase mTOR engages in crosstalk with FoxO3 to control erythroid maturation. Mechanisms underlying FoxO3- mTOR crosstalk in any context are poorly understood. FoxO3 and mTOR were known to have critical independent functions to control autophagy in non-erythroid cells. Autophagy mediates the consumption of damaged cellular components and differentiation-associated cellular remodeling, including mitochondria disposal as a key step in erythrocyte development. We discovered that FoxO3 facilitates GATA-1-instigated autophagy gene activation and accumulation of the autophagosome during erythroid maturation. GATA-1 also activates autophagy by directly inducing FoxO3 expression. We hypothesize that GATA-1-FoxO3 cooperativity controls autophagy and is modulated by mTOR signaling, which would constitute a new paradigm with considerable potential for therapeutic modulation of erythropoiesis and understanding erythroid pathophysiologies. The Bresnick and Ghaffari groups will collectively test this hypothesis and elucidate mechanisms. Aim 1 - To elucidate mechanisms underlying FoxO3 regulation of terminal erythroid maturation. We will test the hypothesis that FoxO3 has a critical function to promote autophagy in late erythroid maturation. We will determine whether FoxO3 stimulates autophagy in steady-state and stress erythropoiesis contexts, if oxidative stress influences erythroid maturation by controlling autophagy, and if mTOR-FoxO3 crosstalk regulates autophagy. As inhibition of mTOR signaling improves anemia in a b-thalassemia model, we will address the potential function of autophagy in b-thalassemia. Aim 2 - To discriminate among models to explain how GATA-1 and FoxO3 cooperatively control autophagy and erythroid maturation. We hypothesize that GATA-1-FoxO3 cooperativity represents a physiological mechanism to control erythroid maturation. We will distinguish between models to understand the cooperativity, which conforms to a type I coherent feed-forward loop, and will determine how it contributes to establishment/maintenance of the erythroid genetic network. Given the importance of GATA and FoxO factors for regulating diverse processes, the studies will yield broad mechanistic and biological insights. (End of Abstract)

描述(由申请人提供)： 阐明调节红系细胞成熟的机制对于设计针对包括地中海贫血、真性红细胞增多症和贫血在内的红细胞疾病的靶向治疗以及开发产生用于临床输血的红细胞的策略至关重要。PI3-激酶-AKT途径促进和抑制红系成熟。其抑制机制涉及AKT介导的FOXO_3的磷酸化，导致FOXO_3滞留在细胞质中。FOXO_3在红系成熟和氧化应激过程中被上调/激活，控制红系细胞周期和成熟、红细胞寿命，并保护免受氧化应激。我们发现了丝氨酸/苏氨酸激酶mTOR与FOXO_3串扰来控制红系成熟的证据。在任何情况下FOXO_3-mTOR串扰的潜在机制都知之甚少。已知FOXO_3和mTOR在控制非红系细胞自噬方面具有重要的独立功能。自噬调节受损细胞成分的消耗和与分化相关的细胞重塑，包括作为红细胞发育关键步骤的线粒体处理。我们发现FOXO_3促进了GATA-1诱导的自噬基因的激活和自噬小体在红系成熟过程中的积累。GATA-1还通过直接诱导FOXO_3的表达来激活自噬。我们假设GATA-1-FOX03的协同作用控制着自噬，并受mTOR信号的调节，这将构成一个具有相当大潜力的新范式，用于治疗调节红细胞生成和了解红系病理生理学。Bresnick和Ghaffari小组将共同测试这一假说，并阐明机制。目的1-阐明FOXO_3调控红系终末成熟的机制。我们将验证FOXO_3在红系成熟后期具有促进自噬的关键功能的假设。我们将确定FOX03是否在稳态和应激红细胞生成环境中刺激自噬，氧化应激是否通过控制自噬影响红系成熟，以及mTOR-FOX03串扰是否调节自噬。由于抑制mTOR信号可以改善b-地中海贫血模型中的贫血，我们将讨论自噬在b-地中海贫血中的潜在作用。目的2-区分不同的模型，以解释GATA-1和FOX03如何协同控制自噬和红系成熟。我们假设GATA-1-FOXO_3的协同作用代表了一种控制红系成熟的生理机制。我们将区分不同的模型以了解协作性，这符合I型相干前馈循环，并将确定它如何有助于红系遗传网络的建立/维持。鉴于GATA和FoxO因子对调控不同过程的重要性，这些研究将产生广泛的机制和生物学见解。 (摘要结束)