铁死亡及其关键蛋白GPX4在造血干细胞功能调控中的作用及机制

The continuous replenishment of hematopoietic system is maintained through the self-renewal and differentiation of hematopoietic stem cells (HSCs). The regulation of HSC function is always the hotspot of stem cell research. Metabolic reprograming during proliferation and differentiation plays critical role in the regulation of HSC function. Ferroptosis is a newly defined mode of regulated cell death caused by the unbalanced lipid redox metabolism. GPX4 is the most important ferroptosis suppressor protein. Ferroptosis has been implicated in many diseases and tumorigenesis. However, the role of ferroptosis on hematopoietic system remains unclear. Our preliminary data showed that GPX4 deficient mice exhibits normal hematopoietic phenotype under homeostasis condition. However, the inhibition and deficiency of GPX4 result in ferroptosis of HSCs in vitro. Moreover, the sensitivity of hematopoietic stem cells and progenitor cells to ferroptosis is negatively correlated with their GPX4 expression level. Based on these findings, this project plans to study the role of GPX4 and ferroptosis in the regulation of HSC function in vivo. Lipidomics, transcriptomics and high-content screening will be applied to study the mechanism. This project explores the relationship between ferroptosis and HSC function modulation. The results will shed light on the physiological significances of ferroptosis on hematopoietic system. Furthermore, it will provide critical references for the development and clinical application of drugs targeting ferroptosis.

造血干细胞（HSC）通过分裂分化维持造血系统，其功能调控是干细胞领域的研究热点。HSC分裂分化时的代谢重编程在功能调控中起关键作用。铁死亡是一种新发现的调节性细胞死亡方式，由脂质氧化还原代谢失衡引起，GPX4是其最重要的抑制蛋白。铁死亡与多种组织器官损伤以及肿瘤密切相关，但它在造血系统中的作用还不清楚。我们前期研究发现，稳态下GPX4基因敲除小鼠造血系统正常，但GPX4受抑制或敲除的HSC在体外扩增时会积累脂质过氧化，发生铁死亡。并且不同种类干祖细胞对铁死亡的敏感程度与GPX4的表达水平呈负相关。本项目拟进一步研究在体内移植和压力应激条件下GPX4和铁死亡对HSC功能的影响，并通过组学分析和基于靶向药物的分子机制筛选寻找调控HSC铁死亡的关键代谢通路和基因。本项目将从铁死亡这一全新角度研究HSC的功能调控，探索铁死亡在造血系统中的生理意义，为以铁死亡为靶标的药物研发及临床应用提供重要参考。

本项目按照计划书内容完成了既定任务。我们发现造血系统中谷胱甘肽过氧化物酶(Gpx4)缺失对小鼠造血干祖细胞(HSPCs)的数量和功能没有显著影响，但Gpx4敲除的造血干细胞(HSCs)和祖细胞(HPCs)在体外会积累脂质过氧化，并发生铁死亡。当给Gpx4敲除小鼠喂食去维生素E饮食时，发现HSPCs脂质过氧化水平升高，数量减少，细胞发生了铁死亡。这些研究证明了GPX4和维生素E协同维持脂质氧化还原平衡并防止HSPCs中的铁死亡。本项目探究了铁死亡在造血系统中的生理意义，同时也为以铁死亡为靶标的药物研发和临床应用提供重要参考。本项目部分工作被Cell Death & Disease期刊(影响因子8.5)接收，共培养了两名硕士研究生顺利毕业。