ENDOTHELIAL CELL-STEM CELL INTERACTIONS

在造血微环境的细胞成分中， 内皮细胞定义了血管和血管之间的界面 造血室及其在造血调控中的作用 直到最近，还没有得到很好的研究。我的实验室报告说 骨髓微血管的分离与鉴定 血管内皮细胞及其长期维持能力 多系造血。使用BMEC派生的表达式库，我们 已经确定了一种分泌的、糖基化的L铁蛋白 血浆浓度在皮摩尔范围内，这是活跃的 支持多能干细胞的增殖。有趣的是， 像许多造血活性细胞因子一样，糖基化L铁蛋白 是四股螺旋束蛋白质家族的一员。生物学 这种新发现的干细胞活性分子是 这项提议。我们的数据表明糖基化的L铁蛋白是 由骨髓微血管内皮细胞分泌并支持 干细胞自我更新。这是通过我们的表达克隆得出的结论 数据以及对纯化的重组人的初步研究 糖基化L铁蛋白。糖基化L铁蛋白的活性为 与KIT-配体(KL)有协同作用。为了探索这一现象的生物学 分子及其发出信号的机制，我们将定义 糖基化L铁蛋白的生物学特性及其对细胞的支持作用 增殖分析中的祖细胞存活和扩增，在模型中 骨髓重建的研究以及旨在揭示其 在造血发育生物学中的作用。我们将定义 糖基化L铁蛋白信号转导机制的研究 定义其与细胞相互作用的性质。它的作用机制 糖基化L铁蛋白与KL的协同作用将用 用于定义伴随着的信号转导事件的转导模型 糖基化L-铁蛋白结合。负责的受体 糖基化的L-铁蛋白的结合和信号转导将被定义。这些 研究将定义一种新发现的造血剂的生物学 具有潜在治疗重要性的细胞因子。

Of the cellular components of the hematopoietic microenvironment, the endothelial cell defines the interface between the vascular and hemopoietic compartments, and its role in the regulation of hemopoiesis has until recently, not been well studied. My laboratory has reported the isolation and characterization of bone marrow microvascular endothelial cells (BMEC) and their ability to sustain long term multilineage hemopoiesis. Using a BMEC-derived expression library we have identified a secreted, glycosylated form of L-ferritin with a plasma concentration in the picomolar range, that is active in supporting the proliferation of pluripotent stem cells. Interestingly, like many hematopoietically active cytokines, glycosylated L-ferritin is a member of the four-helix bundle family of proteins. The biology of this newly recognized stem cell active molecule is the subject of this proposal. Our data suggest that glycosylated L-ferritin is secreted by bone marrow microvascular endothelial cells and supports stem cell self renewal. This is suggested by our expression cloning data as well as by preliminary studies with purified recombinant glycosylated L-ferritin. The activity of glycosylated L-ferritin is synergistic with kit-ligand (KL). To explore the biology of this molecule and the mechanism by which it signals, we will define the biology of glycosylated L-ferritin with respect to its support of progenitor survival and expansion in proliferation assays, in a model of marrow reconstitution, and in studies designed to shed light on its role in the developmental biology of hematopoiesis. We will define the mechanism of glycosylated L-ferritin signaling in studies that will define the nature of its interaction with cells. The mechanism of glycosylated L-ferritin's synergy with KL will be explored using transfection models to define signal transduction events that accompany glycosylated L-ferritin binding. The receptor responsible for glycosylated L-ferritin binding and signaling will be defined. These studies will define the biology of a newly recognized hematopoietic cytokine of potential therapeutic importance.