Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan; Division of Hematology, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
Exp Hematol. 2023 Aug;124:56-67. doi: 10.1016/j.exphem.2023.06.003. Epub 2023 Jun 18.
In physiological conditions, most adult hematopoietic stem cells (HSCs) maintain a quiescent state. Glycolysis is a metabolic process that can be divided into preparatory and payoff phases. Although the payoff phase maintains HSC function and properties, the role of the preparatory phase remains unknown. In this study, we aimed to investigate whether the preparatory or payoff phases of glycolysis were required for maintenance of quiescent and proliferative HSCs. We used glucose-6-phosphate isomerase (Gpi1) as a representative gene for the preparatory phase and glyceraldehyde-3-phosphate dehydrogenase (Gapdh) as a representative gene for the payoff phase of glycolysis. First, we identified that stem cell function and survival were impaired in Gapdh-edited proliferative HSCs. Contrastingly, cell survival was maintained in quiescent Gapdh- and Gpi1-edited HSCs. Gapdh- and Gpi1-defective quiescent HSCs maintained adenosine-triphosphate (ATP) levels by increasing mitochondrial oxidative phosphorylation (OXPHOS), whereas ATP levels were decreased in Gapdh-edited proliferative HSCs. Interestingly, Gpi1-edited proliferative HSCs maintained ATP levels independent of increased OXPHOS. Oxythiamine, a transketolase inhibitor, impaired proliferation of Gpi1-edited HSCs, suggesting that the nonoxidative pentose phosphate pathway (PPP) is an alternative means to maintain glycolytic flux in Gpi1-defective HSCs. Our findings suggest that OXPHOS compensated for glycolytic deficiencies in quiescent HSCs, and that in proliferative HSCs, nonoxidative PPP compensated for defects in the preparatory phase of glycolysis but not for defects in the payoff phase. These findings provide new insights into regulation of HSC metabolism, which could have implications for development of novel therapies for hematologic disorders.
在生理条件下，大多数成人造血干细胞（HSCs）处于静止状态。糖酵解是一种代谢过程，可分为预备阶段和收益阶段。虽然收益阶段维持 HSC 的功能和特性，但预备阶段的作用尚不清楚。在这项研究中，我们旨在研究糖酵解的预备阶段或收益阶段是否需要维持静止和增殖的 HSCs。我们使用葡萄糖-6-磷酸异构酶（Gpi1）作为预备阶段的代表性基因，甘油醛-3-磷酸脱氢酶（Gapdh）作为糖酵解收益阶段的代表性基因。首先，我们确定增殖性 HSCs 中编辑后的 Gapdh 会损害干细胞功能和存活。相比之下，静止的 Gapdh 和 Gpi1 编辑后的 HSCs 维持细胞存活。Gapdh 和 Gpi1 缺陷型静止 HSCs 通过增加线粒体氧化磷酸化（OXPHOS）来维持三磷酸腺苷（ATP）水平，而 Gapdh 编辑的增殖性 HSCs 中 ATP 水平降低。有趣的是，编辑后的 Gpi1 增殖性 HSCs 维持 ATP 水平不依赖于增加的 OXPHOS。噻唑酰胺，一种转酮醇酶抑制剂，损害了 Gpi1 编辑的 HSCs 的增殖，这表明非氧化戊糖磷酸途径（PPP）是维持 Gpi1 缺陷型 HSCs 糖酵解通量的替代途径。我们的发现表明，OXPHOS 补偿了静止 HSCs 中的糖酵解缺陷，而在增殖性 HSCs 中，非氧化 PPP 补偿了糖酵解预备阶段的缺陷，但没有补偿收益阶段的缺陷。这些发现为 HSC 代谢的调节提供了新的见解，这可能对血液疾病的新型治疗方法的发展有影响。
