Estrogen Receptor Signaling in Hematopoietic Stem Cell Proliferation and Mobilization

项目总结 动员外周血中的造血干细胞(HSCs)被广泛应用于临床HSC 移植治疗许多血液疾病。然而，HSC的供应并不充足，而且相当大 许多健康的捐赠者和患者未能通过标准的动员方案动员造血干细胞。因此， 改良的诱导HSC动员和促进造血再生成的策略 为了改善患者的预后，需要通过诱导HSC增殖来进行移植。虽然很尖锐 造血需求促进HSC的增殖和动员，对其分子知之甚少 机械装置。为了更好地了解这些HSC行为是如何调节的，我们使用了小鼠的怀孕 作为一个模范系统。我们先前发现，HSC的增殖、动员和髓外造血 在怀孕期间，当母亲的血液容量迅速膨胀时被诱导。这些反应是依赖于 雌激素受体α(ER-α)对肝星状细胞表达的影响通过这种核激素受体发出的信号可以 由17β-雌二醇(E2)和27-羟基胆固醇(27HC)触发，内源性ER配体是一种 胆固醇的直接代谢物。重要的是，不同的ER配体对ER功能有不同的影响，导致 对基因表达的不同影响。鉴于我们的发现，ERα配体差异地诱导造血干细胞 增殖和动员，我们假设ERα配体的管理和特异性的调节 ERα信号下游的基因可用于改善动员的造血干细胞的收集以用于移植 以及移植后的造血细胞再生。为了检验这一假设，我们提出了以下建议 目标。在目标1中，我们将确定27HC-ERα信号在改善当前肝星状细胞动员方面的潜力 方法：研究方法。结合临床使用的HSC动员剂，我们将给野生型小鼠注射27HC 或具有人源化造血系统的小鼠，并评估动员的小鼠和人的HSCs水平。 在目标2中，我们将确定E2-ERα信号在促进 移植。我们将把小鼠或人的HSC移植到受体小鼠身上，并对这些受体小鼠进行治疗 E2诱导HSC增殖。我们将评估该治疗是否对HSC的增殖有好处 移植后通过增加造血祖细胞进行造血再分化。在目标3中，我们 建议寻找ER-α介导的诱导造血干细胞增殖和动员的关键效应基因。我们会 通过比较HSCs基因表达谱来选择候选基因 下调27HC-ERα信号或E2-ERα信号。我们将从功能上验证他们在HSC中的角色 慢病毒转导体内的增殖和动员。这项研究的成功完成将给我们带来曙光 对HSC增殖和动员的分子机制进行研究，将为HSC的发展奠定基础 获取更多动员的HSCs用于临床移植和促进造血的新干预措施 重新繁衍。

PROJECT SUMMARY Mobilization of hematopoietic stem cells (HSCs) into the peripheral blood is widely used in clinical HSC transplantation to treat many blood disorders. However, the HSC supply is not sufficient and a considerable number of healthy donors and patients fail to mobilize HSCs via the standard mobilization protocol. Thus, improved strategies for inducing HSC mobilization and promoting hematopoietic repopulation after transplantation by inducing HSC proliferation are needed to improve patient outcomes. Although acute hematopoietic demands promote HSC proliferation and mobilization, little is known about the molecular mechanisms. To better understand how these HSC behaviors are regulated, we have used pregnancy in mice as a model system. We previously found that HSC proliferation, mobilization, and extramedullary hematopoiesis are induced during pregnancy when maternal blood volume expands rapidly. These responses are dependent on HSC expression of estrogen receptor α (ERα). Signaling through this nuclear hormone receptor can be triggered by 17β-estradiol (E2) as well as 27-hydroxycholesterol (27HC), the endogenous ER ligand that is a direct metabolite of cholesterol. Importantly, different ER ligands have different effects on ER function, leading to differential effects on gene expression. Given our finding that ERα ligands differentially induce HSC proliferation and mobilization, we hypothesize that administration of ERα ligands and modulation of specific genes downstream of ERα signaling could be used to improve collection of mobilized HSCs for transplantation as well as hematopoietic repopulation after transplantation. To test this hypothesis, we propose the following Aims. In Aim 1, we will determine the potential of 27HC-ERα signaling to improve current HSC-mobilizing methods. In conjunction with clinically-used HSC-mobilizing agents, we will administer 27HC to wild-type mice or mice with humanized hematopoietic systems, and evaluate the levels of mobilized mouse and human HSCs. In Aim 2, we will determine the potential of E2-ERα signaling to enhance hematopoietic repopulation after transplantation. We will transplant mouse or human HSCs to recipient mice and treat these recipient mice with E2 to induce HSC proliferation. We will evaluate whether the treatment has beneficial effects on HSC proliferation and hematopoietic repopulation by increasing hematopoietic progenitors after transplantation. In Aim 3, we propose to identify key effector genes of ERα-mediated induction of HSC proliferation and mobilization. We will select candidate genes by comparing gene expression profiles of HSCs in mice that have either upregulated or downregulated 27HC-ERα signaling or E2-ERα signaling. We will functionally validate their roles in HSC proliferation and mobilization in vivo by lentiviral transduction. Successful completion of this study will shed light on the molecular mechanisms of HSC proliferation and mobilization, and will lay the groundwork for developing novel interventions to harvest more mobilized HSCs for clinical transplantation and to promote hematopoietic repopulation.