The Roles of Lipid Metabolism in the Maintenance of Hematopoietic Stem Cells

摘要 我们研究的一个主要目标是确定指导造血干细胞的关键代谢途径 (HSC)命运的决定虽然早期的研究结果表明，HSC主要依赖于糖酵解，但新的证据表明， 来自我们实验室和其他人的研究表明，线粒体代谢，特别是脂肪酸氧化， 对HSC命运决定至关重要。我们假设线粒体代谢在开始时被重塑， 的命运选择过程，以满足适当的HSC功能不断变化的需求。然而，我们对 HSC自我更新和脂质代谢之间的关系仍然有限。为了鉴定代谢物- 依赖的途径，我们使用了适应基因表达导向的生物信息学工具和我们自己的 代谢组学分析。我们还建立了一种生物传感器，用于评估脂肪酸氧化活性， 活细胞，以确定与HSC受控平衡相关的代谢模式。定量 活成像和我们的单细胞方法将阐明对称或不对称的过程， HSC分裂时线粒体分离。我们创新的本地移植系统将使我们能够 监测体内单个HSC的迁移和细胞分裂，我们建立的图像引导技术， 直接从活动物的骨髓中用微量移液管吸取单个细胞将使随后的 单细胞测定。对所得数据的分析将对HSC的命运决定过程产生新的见解， 并促进新的治疗策略的发展，使HSC的分裂平衡向自体转移， 通过代谢控制来更新。本提案的目标有三个方面：（1）在目标1中，我们将诱导 选择性消耗线粒体中的代谢物，以确定脂肪酸的代谢靶点 在目标2中，我们将使用药理学或遗传学调节关键基因， 影响脂肪酸氧化或其下游靶点以确定线粒体之间的代谢串扰 和胞质溶胶;（3）在目标3中，我们将评估产生HSC分裂对称性的协调过程， 体内，分裂平衡的分析将提供对脂肪酸代谢的体内相关性的见解， HSC命运选择。如果成功，拟议的研究将通过提供更深入的研究， 了解协调HSC命运决定的代谢线索，并将提出潜在的方法， 通过代谢操纵将HSC的分裂平衡转向自我更新，以改善临床 移植后的结果。

ABSTRACT A leading goal of our research is identification of the key metabolic pathways directing hematopoietic stem cell (HSC) fate decisions. While early findings suggested that HSCs depend mainly on glycolysis, emerging evidence from our lab and others has shown that mitochondrial metabolism, and particularly fatty acid oxidation, is essential to HSC fate determination. We hypothesize that mitochondrial metabolism is remodeled at the initiation of the fate choice process to meet the changing needs of proper HSC function. However, our understanding of the relationship between HSC self-renewal and lipid metabolism remains limited. To identify metabolite- dependent pathways, we have used an adapted gene expression-oriented bioinformatics tool and our own metabolomics analyses. We have also established a biosensor for assessment of fatty acid oxidation activity in live cells to determine the metabolic modes which are relevant to the controlled equilibrium of HSCs. Quantitative live imaging and our single cell approaches will illuminate the processes of symmetric or asymmetric mitochondrial segregation during HSC division. Our innovative local transplantation system will allow us to monitor the migration and cell divisions of single HSCs in vivo, and our established image-guided technique of micropipette aspiration of individual cells directly from the bone marrow of live animals will enable subsequent single-cell assay. Analysis of the resulting data will yield new insights into the fate decision process of HSCs, and facilitate the development of new therapeutic strategies for shifting the division balance of HSCs toward self- renewal through metabolic manipulation. The goals of this proposal are three-fold: (1) In Aim 1, we will induce the selective consumption of metabolites localized in the mitochondria to identify metabolic targets of fatty acid metabolism that affect HSC fate; (2) in Aim 2, we will use pharmacological or genetic modulation of key genes impacting fatty acid oxidation or its downstream targets to define the metabolic crosstalk between mitochondria and the cytosol; and (3) in Aim 3 we will evaluate the coordinated process that yields HSC division symmetry in vivo, and analysis of division balance will provide insights into the in vivo relevance of fatty acid metabolisms to HSC fate choice. If successful, the proposed research will positively impact the field by providing a deeper understanding of the metabolic cues coordinating HSC fate decisions, and will suggest potential methods of shifting the division balance of HSCs toward self-renewal through metabolic manipulation to improve clinical outcomes after transplantation.