Estrogen Receptor Signaling in Hematopoietic Stem Cell Proliferation and Mobilization

项目摘要 动员造血干细胞进入外周血是目前临床上广泛应用的造血干细胞治疗方法 移植治疗多种血液疾病。然而，HSC供应不足， 许多健康供体和患者未能通过标准动员方案动员HSC。因此，在本发明中， 诱导HSC动员和促进造血重建的改进策略 需要通过诱导HSC增殖进行移植来改善患者的结果。虽然急性 造血需求促进HSC增殖和动员，但对HSC增殖和动员的分子机制知之甚少。 机制等为了更好地了解这些HSC行为是如何调节的，我们使用了小鼠妊娠 作为一个模型系统。我们以前发现HSC增殖、动员和髓外造血 是在怀孕期间母体血容量迅速膨胀时诱发的。这些反应依赖于 对HSC雌激素受体α（ERα）表达的影响。通过这种核激素受体的信号可以 由17β-雌二醇（E2）和27-羟基胆固醇（27 HC）触发，27 HC是内源性ER配体， 胆固醇的直接代谢产物。重要的是，不同的ER配体对ER功能具有不同的影响， 对基因表达的不同影响。鉴于我们发现ERα配体差异诱导HSC 增殖和动员，我们假设给予ERα配体和调节特异性的 ERα信号下游的基因可用于提高动员的HSC的收集用于移植 以及移植后造血再生。为了验证这一假设，我们提出以下建议： 目标。在目标1中，我们将确定27 HC-ER α信号传导改善当前HSC动员的潜力。 方法.结合临床使用的HSC动员剂，我们将27 HC给予野生型小鼠 或具有人源化造血系统的小鼠，并评估动员的小鼠和人HSC的水平。 在目标2中，我们将确定E2-ERα信号转导增强造血重建的潜力， 移植我们将小鼠或人HSC移植到受体小鼠，并用 E2诱导HSC增殖。我们将评估治疗是否对HSC增殖有有益的影响 以及通过增加移植后的造血祖细胞来实现造血再生。在目标3中， 目的：鉴定ERα介导的HSC增殖和动员的关键效应基因。我们将 通过比较小鼠中HSC的基因表达谱来选择候选基因， 下调27 HC-ER α信号或E2-ERα信号。我们将从功能上验证他们在HSC中的作用 通过慢病毒转导在体内增殖和动员。这项研究的成功完成将揭示 探讨HSC增殖和动员的分子机制，为进一步研究HSC的增殖和动员机制奠定基础。 新的干预措施，以收获更多的动员HSC用于临床移植，并促进造血干细胞的再生。 再繁殖

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.