Defining Estrogenic Regulation of Hematopoietic Stem Cell Formation and Function

描述(由申请人提供)：近几十年来，接触环境和饮食中干扰内分泌信号的物质的情况急剧增加。虽然雌激素化合物对生殖系统功能的影响已经得到了很好的研究，但关于其他器官，特别是造血系统是如何受到影响的，却知之甚少。最终的造血干细胞(HSCs)可以自我更新和分化，在个体的整个生命周期中产生每一个成熟的血细胞谱系。由于遗传性或获得性遗传异常，HSC形成或分化的缺陷可导致骨髓衰竭和白血病。大多数参与HSC形成的基因在脊椎动物中高度保守，并继续调节成年HSC的自我更新和分化。转录因子RUNX1是白血病中常见的染色体突变靶点，在所有新生造血部位都有表达，是哺乳动物诱导HSC所必需的；斑马鱼中RUNX1的表达是保守的。通过斑马鱼对RUNX1表达修饰物的化学筛选，主要研究人员确定了调节雌激素信号的化合物是HSC形成的潜在调节因素。他们假设，环境雌激素通过其雌激素功能对HSC的发育产生影响，接触这些化合物可能会产生长期的负面影响。他们的长期目标是了解环境雌激素影响造血的分子和细胞机制。本研究的目的是描述环境雌激素暴露对斑马鱼和小鼠在发育和损伤后恢复过程中肝星状细胞的形成、增殖和功能的影响和脆弱时期。核心假设是雌激素类化合物在发育的多个不同时期影响HSC的形成，影响红系原始波、血管造血生态位的形成和HSC的增殖。这一假说是从他们的筛查结果和随后对导致HSC形成的不同时间段的评估中得出的。这项工作的基本原理是，一个详细的 了解环境雌激素对血液干细胞生长和增殖的影响，将有助于更深入地了解接触环境雌激素化合物的后果，而不仅仅是它们对生殖器官的作用。在特定的目标1中，他们将研究雌激素信号在斑马鱼造血发育和损伤恢复过程中对HSC规格和增殖的影响。特别是，他们将确定雌激素作用的细胞和分子靶点，以及有机体特别容易受到其影响的发育阶段。在特定的目标2中，他们将分析异种雌激素(双酚A)、饮食中的植物雌激素(染料木素)和真菌雌激素(玉米赤霉烯酮)在HSC形成过程中的特定作用；他们将证明这些影响是由雌激素信号的特异性激活所介导的。通过小鼠实验，他们将研究这些化合物如何影响脊椎动物物种间的HSC功能。

DESCRIPTION (provided by applicant): Exposure to substances in the environment and the diet that disrupt endocrine signaling has dramatically increased in recent decades. While the effects of estrogenic compounds on the function of the reproductive system has been well studied, much less is known about how other organs, particularly the hematopoietic system, are impacted. Definitive hematopoietic stem cells (HSCs) both self-renew and differentiate to produce each of the mature blood cell lineages for the entire lifespan of the individual. Defects in HSC formation or differentiation, as a result of inherited or acquired genetic aberrations, can lead to bone marrow failure and leukemia. Most genes involved in HSC formation are highly conserved across vertebrates, and continue to regulate HSC self-renewal and differentiation in the adult. The transcription factor RUNX1, a frequent target of chromosomal mutation in leukemia, is expressed in all sites of de novo hematopoiesis and is absolutely required for HSC induction in mammals; runx1 expression is conserved in zebra fish. Through a zebra fish chemical screen for modifiers of runx1 expression, the principal investigators identified compounds that modulate estrogen signaling as potential regulators of HSC formation. They hypothesize that environmental estrogens exert an effect on HSC development through their estrogenic function and that exposure to these compounds could have long-lasting negative effects. Their long-term goal is to understand the molecular and cellular mechanisms by which environmental estrogens affect hematopoiesis. The objective here is to characterize the functional implications and vulnerable periods of environmental estrogen exposure on HSC formation, proliferation and function during development and recovery after injury, in both zebra fish and mice. The central hypothesis is that estrogenic compounds impact HSC formation during multiple distinct periods during development, affecting the primitive wave of erythropoiesis, the formation of the vascular hematopoietic niche and HSC proliferation. This hypothesis has been derived from their screening results and subsequent evaluation of the different time periods contributing to HSC formation. The rationale for the work is that a detailed understanding of the impact of environmental estrogens on blood stem cell growth and proliferation will enable a deeper understanding of the consequences of exposure to environmental estrogenic compounds beyond their action on reproductive organs. In Specific Aim 1, they will investigate the effects of estrogen signaling on HSC specification and proliferation during hematopoietic development and recovery from injury in zebra fish. In particular, they will identify the cellular and molecular targets of estrogen action and the developmental stages during which the organism is particularly vulnerable to its effects. In Specific Aim 2, they will analyze the specific effects of xenoestrogens (bisphenol A), dietary phytoestrogens (genistein), and mycoestrogens (zearalenone) during HSC formation; they will demonstrate that these effects are mediated by specific activation of estrogen signaling. Using murine assays, they will examine how these compounds effect HSC function across vertebrate species.