Role of EPO in terminal erythroid maturation

描述(由申请人提供)： 这项建议的总体目标是更好地了解终末红系细胞成熟的细胞和分子基础。我们的红细胞量是由主要依赖于促红细胞生成素(EPO)的强大的细胞成熟过程维持的。EPO通过其同源受体(EPOR)向晚期确定的红系祖细胞提供关键的生存信号，这使得研究其在红系前体下游末端成熟中的作用变得困难。虽然EPO被广泛认为是最终的红细胞生成所必需的，但它在原始红细胞生成中的作用仍然存在争议，而且了解很少。原始红细胞生成是胚胎生长和存活所必需的一种短暂谱系。我们假设EPO在原始红系血统的终末成熟过程中起中心作用。这一假设 将通过描述EPO在缺乏EPOR的小鼠胚胎中的作用以及在体外两步原始红系培养系统中的作用，在Aim 1研究中进行测试。我们最近对辐射的研究 对骨髓的损伤使我们假设，终末红系细胞成熟的特征是从促凋亡状态向抗凋亡状态的转变(Peslak，2011)。初步研究表明，EPO可抑制晚期原始红系前体细胞的凋亡。突变的原始红系细胞在EPOR缺失的胚胎中的持续存在为研究EPO在红系细胞成熟末期的作用提供了一个独特的机会。我们已经确定了促凋亡和抗凋亡基因，它们的水平因EPO的丢失而发生显著变化。在目标2中，我们将更全面地描述野生型和EPOR缺失型红细胞中促凋亡和抗凋亡基因的表达。此外，我们还将阐明STAT信号在野生型和缺乏STAT5信号的突变型原始红细胞中调控BclxL的作用。通过比较，我们对红系成熟后期EPO功能的研究可能最终为临床上重要的细胞因子在EPO反应的非红系细胞中的作用提供洞察力，无论是正常的还是恶性的。 (摘要结束)

DESCRIPTION (provided by applicant): The overall aim of this proposal is to better understand the cellular and molecular underpinnings of terminal erythroid cell maturation. Our red cell mass is sustained by a robust process of cell maturation that is primarily dependent on the hormone erythropoietin (EPO). EPO, signaling through its cognate receptor (EPOR) provides a critical survival signal to late-stage definitive erythroid progenitors making it difficult to study its role in the downstream terminal maturation o erythroid precursors. While EPO is widely recognized to be essential for definitive erythropoiesis, its role in primitive erythropoiesis, a transient lineage necessary for embryonic growth and survival, remains controversial and poorly understood. We hypothesize that EPO plays a central role in the terminal maturation of the primitive erythroid lineage. This hypothesis will be tested in Aim 1 studies by delineating the role of EPO in mouse embryos lacking EPOR as well as in an ex vivo 2-step primitive erythroid culture system. Our recent studies of radiation injury to the bone marrow have led us to hypothesize that terminal erythroid cell maturation is characterized by a transition from a pro-apoptotic to an anti-apoptotic state (Peslak, 2011). Preliminary studies indicate that EPO prevents the apoptosis of late-stage primitive erythroid precursors. The persistence of mutant primitive erythroid cells in EPOR-null embryos provides a unique opportunity to investigate the role of EPO in terminal stages of erythroid cell maturation. We have identified pro- and anti-apoptotic genes whose levels are dramatically altered by loss of EPO. In Aim 2, we will more fully characterize the expression of pro- and anti-apoptotic genes in wild-type and EPOR-null erythroblasts. Furthermore, we will delineate the role of Stat signaling in the regulation of Bcl-xL both in wild- type and in mutant primitive erythroblasts lacking Stat5 signaling. Our studies of EPO function in late stages of erythroid maturation may ultimately provide insights, by comparison, into the role of this clinically important cytokine in EPO-responsive non-erythroid cells, both normal and malignant. (End of Abstract)