AKT Signaling and Oxidative Stress Regulation of Erythropoiesis

红系细胞分裂和成熟的紧密协调是日常生产红系细胞所必需的。 细胞和对需要应激红细胞生成的临床病症的立即反应。成熟 红系祖细胞和早期成红细胞（红系前体）是高度增殖的，而增殖 在后期急剧下降。阐明调节红系细胞分化的分子途径 成熟对于设计针对许多红系疾病的靶向治疗至关重要， 红白血病、地中海贫血和真性红细胞增多症。促红细胞生成素（Epo）结合产生的信号 促红细胞生成素受体（EpoR）是由JAK 2酪氨酸激酶介导的， 正常的红细胞发育。虽然EpoR信号在红系细胞凋亡调控中的作用尚不清楚， 存活和细胞分裂的特征已经被广泛地描述，EpoR信号传导对细胞分裂的影响已经被广泛地描述。 红系细胞分化和成熟的转录程序还不太清楚。尤其是， 关于协调红系前体细胞分裂，细胞周期退出， 分化和成熟。我们实验室的证据表明，AKT丝氨酸苏氨酸蛋白 激酶在调节红系细胞分裂和成熟的下游介导重要的功能， EpoR信号。我们已经鉴定了AKT对加塔-1和FoxO 3转录因子以及mTOR的调节作用， 激酶作为协调红系细胞分裂和成熟的关键。此外，我们的研究支持 AKT靶向FoxO 3对生理活性氧（ROS）的调节在细胞凋亡中起着重要作用。 在红系细胞成熟中的作用。ROS被认为在许多红系疾病中起关键作用，包括在 地中海贫血性红细胞生成因此，我们提出了一个模型，在该模型中，AKT下游的信号，特别是 FoxO 3、mTOR和加塔-1协调红系前体细胞的分裂和成熟， 配位至少部分由ROS介导。为了研究这个模型的有效性，我们提出了 目的1：探讨FoxO 3在应激红细胞生成中的作用;目的2：探讨FoxO 3在应激红细胞生成中的作用。 阐明野生型和FoxO 3敲除小鼠红系细胞增殖的分子机制; 探讨AKT对加塔-1的调控机制。在这些实验中，我们将评估 ROS的贡献和mTOR的作用。最后，我们将研究FoxO 3在体内的潜在功能- 地中海贫血这些研究的结果将提供有关调节机制的关键信息， 红系细胞分裂和成熟，并应阐明红细胞生成的基本方面。

A tight coordination of erythroid cell division and maturation is required for daily production of erythroid cells and for immediate response to clinical conditions in which stress erythropoiesis is in demand. Mature erythroid progenitors and early erythroblasts (erythroid precursors) are highly proliferative, while proliferation decreases sharply in later stages. Elucidating molecular pathways that regulate erythroid cell differentiation and maturation is critical for devising targeted treatments for a number of erythroid disorders including erythroleukemias, thalassemias, and polycythemia vera. Signals generated from Erythropoietin (Epo) binding to its receptor erythropoietin receptor (EpoR) are mediated by JAK2 tyrosine kinase and are essential for normal erythroid cell development. Although the function of EpoR signaling in the regulation of erythroid survival and cell division has been characterized extensively, the impact of EpoR signaling on the transcriptional program of erythroid cell differentiation and maturation is less well understood. Particularly, not much is known about molecular mechanisms that coordinate erythroid precursor cell division, cell cycle exit, and differentiation and maturation. Evidence from our laboratory suggests that AKT serine threonine protein kinase mediates significant functions in the regulation of erythroid cell division and maturation downstream of EpoR signaling. We have identified AKT regulation of GATA-1 and FoxO3 transcription factors and mTOR kinase as critical for coordination of erythroid cell division and maturation. In addition our studies support the notion that regulation of physiological reactive oxygen species (ROS) by AKT target FoxO3 plays a significant role in erythroid cell maturation. ROS is thought to play a critical role in many erythroid disorders including in ¿-thalassemic erythropoiesis. Thus we propose a model in which signals downstream of AKT, specifically FoxO3, mTOR and GATA-1 coordinate erythroid precursor cell division and maturation and that this coordination is mediated at least in part by ROS. To investigate the validity of this model we propose the following aims: Aim 1: To investigate the role of FoxO3 in response to stress erythropoiesis; Aim 2: To elucidate the molecular mechanisms of erythroid cell proliferation in wild type and FoxO3 null mice; To investigate the mechanisms of AKT regulation of GATA-1. In these experiments we will evaluate the contribution of ROS and the role of mTOR. Finally we will examine the potential function of FoxO3 in ¿- thalassemia. Results from these studies will provide critical information on mechanisms of regulation of erythroid cell division and maturation, and should shed light on fundamental aspects of erythropoiesis.