Intrinsic and extrinsic control of erythropoietic maturation

描述（由申请人提供）：红细胞生成的最终分化事件不是孤立发生的，而是在一个称为红母细胞岛的特殊生态位中发生的，黏附巨噬细胞-红细胞相互作用对其完整性很重要，它有效地帮助红细胞从红母细胞成熟到去核网状细胞。特异粘附分子的表达和核缩聚效应在这一过程中都是至关重要的。然而，编码这些分子的基因的表达是如何协调的还没有确定。EKLF/KLF1（红细胞红细胞样因子）通过整合特定位点的转录和表观遗传信号，在红细胞生成过程中发挥全局作用。因此，在分化后期发挥这样的作用是值得考虑的。这一猜想得到了小鼠胚胎干细胞分化实验、相关EKLF靶点的鉴定、发育过程中EKLF的早期和局部表达、EKLF缺失的胎儿肝细胞所表现出的缺陷、EKLF表达模式的惊人扩展以及先天性红细胞生成障碍性贫血患者亚群中的红细胞表型的支持。这些构成了以下目标的基础：1 .研究EKLF在早期发育和成年期间红母细胞岛形成和完整性中的作用2 .阐述EKLF在岛巨噬细胞中的意想不到的作用3 .利用原代红细胞的增殖/分化系统来解决EKLF协调核成熟事件的能力。本研究旨在验证EKLF在两个过程中起协调作用的假设，这两个过程在红母细胞岛生态位的背景下密切相关：粘附

DESCRIPTION (provided by applicant): The terminal differentiation events of erythropoiesis do not occur in isolation, but rather within a specialized niche known as the erythroblastic island Adhesive macrophage-erythroid cell interactions are important for its integrity, which efficiently aid the red cell maturation progression from erythroblast to enucleated reticulocyte. Expression of specific adhesion molecules and nuclear condensation effectors each are critical for this process. However, how expression of the genes encoding these molecules is coordinated is not established. EKLF/KLF1 (erythroid Kr�ppel-like factor) plays a global role in erythropoiesis by integrating transcriptional and epigenetic signals at specific loci. As a result, it merits consideration for performing such a role at late stages of differentiation. Such a conjecture is supported by experiments in differentiating murine embryonic stem cells, identification of relevant EKLF targets, its early and localized expression during development, deficiencies exhibited by EKLF-null fetal liver cells, the surprising expansion of EKLF expression pattern, and the red cell phenotype in a subset of congenital dyserythropoietic anemia patients. These form the basis for the following aims: 1-Investigate the role of EKLF in erythroblastic island formation and integrity during early development and in the adult 2-Elaborate on EKLF's unexpected role in the island macrophage 3-Utilize a proliferation/differentiation system of primary erythroid cells to address EKLF's ability to coordinate nuclear maturation events. This proposal is designed to test the hypothesis that EKLF plays a coordinating role in two processes that are intimately interconnected within the context of the erythroblastic island niche: adhesive erythroid-macrophage/cell-cell interactions, and enucleation of the red cell. Our studies build on observations made in primary or minimally manipulated cells that will be aided by in vivo assays and EKLF rescue systems. Our proposed experiments raise and will address the exciting idea that EKLF not only plays an intrinsic role in establishing the proper gene expression patterns in the red cell within the erythroblastic island, but that it additionally affects this process by an extrinsic mechanism based on its unanticipated expression within the island macrophage. Understanding these basic mechanisms will ultimately aid in the design of culture systems that enable efficient expansion and enucleation of human cell sources for clinical use.