Novel Determinants of Terminal Erythroid Maturation

红细胞终末成熟的新决定因素

• 批准号: 8417051
• 负责人: Emery H Bresnick
• 金额: $ 41.18万
• 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/8417051
• 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）： 阐明调节红细胞成熟的机制对于设计红细胞疾病（包括地中海贫血、真性红细胞增多症和贫血）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。PI 3-激酶-AKT通路促进和抑制红细胞成熟。抑制机制涉及AKT介导的FoxO 3磷酸化，这导致其在细胞质中的隔离。FoxO 3在红细胞成熟过程中和通过氧化应激上调/激活，并控制红细胞周期和成熟、红细胞寿命，并保护免受氧化应激。我们开发的证据表明，丝氨酸/苏氨酸激酶mTOR从事串扰与FoxO 3控制红细胞成熟。在任何情况下FoxO 3- mTOR串扰的机制都知之甚少。已知FoxO 3和mTOR具有控制非红系细胞中自噬的关键独立功能。自噬介导受损细胞成分的消耗和分化相关的细胞重塑，包括线粒体处置作为红细胞发育的关键步骤。我们发现FoxO 3促进了加塔-1-激发的自噬基因激活和红系成熟过程中自噬体的积累。加塔-1还通过直接诱导FoxO 3表达来激活自噬。我们假设加塔-1-FoxO 3协同性控制自噬，并通过mTOR信号转导进行调节，这将构成一个新的范例，具有相当大的潜力，用于治疗调节红细胞生成和理解红细胞病理生理学。Bresnick和Ghaffari小组将共同验证这一假设并阐明机制。目的1 -阐明FoxO 3调控红系终末成熟的机制。我们将测试的假设，FoxO 3有一个关键的功能，以促进自噬在红细胞成熟后期。我们将确定FoxO 3是否在稳态和应激红细胞生成背景下刺激自噬，氧化应激是否通过控制自噬影响红细胞成熟，以及mTOR-FoxO 3串扰是否调节自噬。由于mTOR信号传导的抑制改善了b-地中海贫血模型中的贫血，我们将解决自噬在b-地中海贫血中的潜在功能。目的2 -区分模型以解释加塔-1和FoxO 3如何协同控制自噬和红细胞成熟。我们假设加塔-1-FoxO 3协同性代表了控制红细胞成熟的生理机制。我们将区分模型，以了解协同性，这符合I型相干前馈回路，并将确定它如何有助于建立/维持红细胞遗传网络。鉴于加塔和FoxO因子对调节不同过程的重要性，这些研究将产生广泛的机制和生物学见解。 (End摘要）