Metabolic regulation of hematopoietic stem cell specification and function

描述(申请人提供)：代谢紊乱，包括肥胖和糖尿病，是美国可预防的死亡的主要原因。妊娠期糖尿病的发病率也同样增加。生理性升高的血糖水平对造血的影响尚未确定。造血干细胞(HSCs)对于生存至关重要，因为它们的功能是在整个生物体的生命周期中产生每一种成熟的血细胞谱系。第一批HSC起源于主动脉-性腺-中肾(AGM)区的血源性内皮细胞。大多数参与HSC形成的基因，如RUNX1，在脊椎动物中高度保守，并继续调节成年HSC的动态平衡。我们已经成功地使用斑马鱼来识别脊椎动物HSCs的新调节因子，从而导致了FDA批准的第一个源于斑马鱼研究的临床试验。为了评估代谢调节对HSC的影响，我们将斑马鱼胚胎暴露于增加生理剂量的葡萄糖中，并观察到高葡萄糖水平增强了胚胎HSC形成的时间和数量。我们的长期目标是描述营养供应对HSC形成和功能的影响。我们的目标是研究糖代谢调节对脊椎动物胚胎中HSC诱导、增殖和分化的影响。我们的中心假设是，葡萄糖代谢通过产生ROS和随后的HIF1α稳定来影响造血干细胞的形成，从而驱动造血基因的协调表达。我们工作的基本原理是了解生理性血糖波动的影响 对造血干细胞的研究将阐明造血系统代谢失调的潜在风险，这对免疫有长期影响。在具体目标1中，我们将评估高糖对HSC发生和发展的时空影响。利用代谢的化学和遗传调控，我们将确定葡萄糖通过HIF1α影响与肝星状细胞相关的转录调控的机制。我们的初步数据显示，生理性血糖升高显著加速了HSC的诱导。在特定的目标2中，我们将评估急性和慢性高血糖以及协调的HIF1α靶基因调控对肝星状细胞功能的影响。我们将在成人损伤模型、小鼠妊娠期糖尿病模型和人脐血中证实这些效应的进化保守性。我们的初步数据表明，葡萄糖暴露促进了骨髓损伤后的恢复，而AGM和胎盘中HIF1α的活性与HSC的产生有关，这表明葡萄糖代谢是一个保守的调节因素。这一建议的预期结果是详细了解葡萄糖代谢介导的HSC调节的时空动力学和分子机制。这些结果将使我们深入了解发育中的生物体如何感知和响应营养供应的波动，以匹配造血输出和预期的增长率，并将直接影响我们对妊娠期糖尿病对造血和治疗性HSC调节的风险的理解。

DESCRIPTION (provided by applicant): Metabolic disorders, including obesity and diabetes, are the leading cause of preventable death in the U.S. The incidence of gestational diabetes has similarly increased. The impact of physiologically elevated glucose levels on hematopoiesis is not established. Hematopoietic stem cells (HSCs) are essential for survival, as they function to produce each of the mature blood cell lineages throughout the lifespan of the organism. The first HSCs arise from hemogenic endothelium in the aorta-gonad-mesonephros (AGM) region. Most genes involved in HSC formation, such as RUNX1, are highly conserved across vertebrates, and continue to regulate HSC homeostasis in the adult. We have successfully used zebrafish to identify novel regulators of vertebrate HSCs, resulting in the first FDA-approved clinical trial originating from zebrafish studies. To assess the impact of metabolic regulation on HSCs, we exposed zebrafish embryos to increasing physiological doses of glucose and observed that elevated glucose levels enhanced the timing and magnitude of embryonic HSC formation. Our long-term goal is to characterize the impact of nutrient availability on HSC formation and function. Our objective here is to characterize the effects of modulation of glucose metabolism on HSC induction, proliferation and differentiation in the vertebrate embryo. Our central hypothesis is that glucose- metabolism impacts HSC formation via production of ROS and subsequent hif1α stabilization to drive coordinate expression of hematopoietic genes. The rationale for our work is that an understanding of the impact of physiological glucose fluctuations on HSCs will elucidate potential risks of dysregulated metabolism on the hematopoietic system, which has long-term consequences for immunity. In Specific Aim 1, we will assess the impact of excess glucose on the spatio-temporal onset and progression of HSC development. Using chemical and genetic modulation of metabolism, we will identify the mechanism by which glucose impacts HSC-related transcriptional regulation via hif1α. Our preliminary data show physiological glucose elevation significantly accelerates HSC induction. In Specific Aim 2, we will assess the impact of acute versus chronic hyperglycemia and coordinated hif1α target gene regulation on HSC function. We will confirm the evolutionary conservation of these effects in an adult injury model, murine gestational diabetes models and in human umbilical cord blood. Our preliminary data indicate glucose exposure enhances recovery after marrow injury and hif1α activity in the AGM and placenta correlates with HSC production, suggesting glucose metabolism is a conserved regulatory factor. The expected outcomes of this proposal are a detailed understanding of the spatio-temporal dynamics and molecular mechanisms of glucose metabolism-mediated HSC regulation. These results will provide insight into how the developing organism senses and responds to fluctuations in nutrient supply to match hematopoietic output with anticipated growth rates, and will have a direct impact on our understanding of the risks of gestational diabetes on hematopoiesis and for therapeutic HSC modulation.