Defining Estrogenic Regulation of Hematopoietic Stem Cell Formation and Function

描述（由申请人提供）：近几十年来，暴露于环境和饮食中干扰内分泌信号的物质急剧增加。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，但对其他器官，特别是造血系统的影响知之甚少。造血干细胞（HSC）自我更新和分化，以产生个体整个生命周期的每一种成熟血细胞谱系。由于遗传或获得性遗传畸变导致的HSC形成或分化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，并继续调节成体HSC的自我更新和分化。转录因子RUNX 1是白血病中染色体突变的常见靶标，在从头造血的所有位点中表达，并且是哺乳动物中HSC诱导所绝对需要的; runx 1表达在斑马鱼中是保守的。通过对斑马鱼进行runx 1表达修饰剂的化学筛选，主要研究人员确定了调节雌激素信号的化合物作为HSC形成的潜在调节剂。他们假设环境雌激素通过其雌激素功能对HSC发育产生影响，并且暴露于这些化合物可能具有长期的负面影响。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。本研究的目的是探讨斑马鱼和小鼠在损伤后发育和恢复过程中，环境雌激素暴露对HSC形成、增殖和功能的影响及其脆弱期。中心假设是雌激素化合物在发育过程中的多个不同时期影响HSC形成，影响红细胞生成的原始波、血管造血生态位的形成和HSC增殖。这一假设是根据他们的筛查结果和随后对促成HSC形成的不同时间段的评估得出的。这项工作的基本原理是， 了解环境雌激素对造血干细胞生长和增殖的影响，将使我们能够更深入地了解暴露于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。在具体目标1中，他们将研究雌激素信号传导对斑马鱼造血发育和损伤恢复过程中HSC特异性和增殖的影响。特别是，他们将确定雌激素作用的细胞和分子靶点，以及生物体特别容易受到其影响的发育阶段。在具体目标2中，他们将分析异种雌激素（双酚A），膳食植物雌激素（染料木黄酮）和真菌雌激素（玉米赤霉烯酮）在HSC形成过程中的具体作用;他们将证明这些作用是由雌激素信号的特异性激活介导的。使用小鼠试验，他们将研究这些化合物如何影响脊椎动物物种的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.