骨髓微环境动态表达IGF2调控造血干细胞代谢适应的机制研究

Precise regulation between hematopoietic stem cells (HSCs) and niche cells is critical for maintaining normal hematopoiesis, otherwise it may be expected to result in bone marrow failure or clonal proliferative diseases. During different stages of development, HSCs fulfil the hematopoiesis in distinct niches, such as fetal liver and bone marrow. However, how HSCs adapt to the new niches is poorly understood. Our preliminary results showed that the cell cycle of HSCs immediately transfer from proliferative state to a quiescent state after migrating from fetal liver to bone marrow in newborn mice. However, the dynamic change of the metabolic state is in line with that of the bone marrow niche (especially expression level of IGF2), indicating that the bone marrow niche derived IGF2 can regulate the metabolic adaptations of HSCs. Our study intends to observe the dynamic process of cell cycle and metabolic changes of HSCs in the neonatal period of mice by flow cytometry and whole-mount immunofluorescence, and study the dynamic changes and expression profiles of HSCs and bone marrow niche cells using fluorescent cell sorting and RNA sequencing (RNA-seq), and explore the molecular mechanism of bone marrow niche derived IGF2 in the regulation of HSC metabolic adaptation by molecular biological methods and conditional knock-out mice. Thereby, research findings may reveal the molecular mechanism how HSCs adapt to the dynamic changes of microenvironment at different stages of development, and provide a theoretical basis for tracing the origin, occurrence and development of hematological diseases.

造血干细胞（HSC）与微环境细胞之间的精确调控对于维持正常造血至关重要，失调会导致骨髓衰竭或克隆增生性疾病。发育不同阶段，HSC在不同微环境（如胚肝和骨髓）中完成造血。然而，HSC如何适应新的微环境尚不清楚。我们前期结果显示，在新生小鼠中，HSC从胚肝迁移至骨髓后，细胞周期即刻由增殖状态转变为静止状态，而代谢状态变化则与骨髓微环境的动态变化（特别是IGF2的表达水平）一致，提示骨髓微环境源性IGF2调控HSC的代谢适应。本项目拟采用流式分析和全组织荧光等技术观察新生期HSC周期和代谢变化的动态过程；利用流式分选和RNA-seq等手段研究HSC和骨髓微环境主要细胞组份动态变化规律和表达谱差异；通过分子生物学手段和条件敲除小鼠等工具探讨骨髓微环境源性IGF2调控HSC代谢适应的分子机制。从而揭示HSC在发育不同时期适应微环境动态变化的分子机理，为追溯造血系统疾病起源及发生发展提供理论依据。

本项目拟探讨生理性骨髓微环境（Niche）中造血干细胞（HSC）代谢变化的调控机制。HSC与微环境细胞之间的精确调控对于维持正常造血至关重要，失调会导致骨髓衰竭或克隆增生性疾病。发育不同阶段，HSC在不同微环境中完成造血。然而，HSC如何适应新的微环境尚不清楚。我们前期结果显示，在新生小鼠中，HSC从胚肝迁移至骨髓后，细胞周期即刻由增殖状态转变为静止状态，而代谢状态变化则与骨髓微环境的动态变化（特别是IGF2的表达水平）一致，提示骨髓微环境源性IGF2调控HSC的代谢适应。本项目重点探讨：1）观察新生期HSC周期和代谢变化的动态过程；2）研究HSC和骨髓微环境主要细胞组份动态变化规律和表达谱差异；3）探讨骨髓微环境源性IGF2调控HSC代谢适应的分子机制。我们的研究表明：骨髓微环境来源的IGF2通过结合其受体调控PI3K-AKT-mTOR信号通路，从而调控HSC的代谢变化。阐明了生理性骨髓niche中HSC代谢适应的调控新机制。此外，我们延续之前的研究方向，新增了血液肿瘤治疗方面的转化研究，主要发现包括：1）靶向DNA聚合酶β引起急性淋巴细胞白血病错配修复缺陷的合成致死；2）核酸适体探针快速检测IgG1型抗体药物和筛选出高表达抗体药物生产细胞株；3）双特异性抗体联合CAR-T治疗血液肿瘤的转化研究发现；4）干细胞样CD8+ T细胞参与白血病免疫治疗新机制。本项目揭示HSC在发育不同时期适应微环境动态变化的分子机理，为追溯造血系统疾病起源及发生发展提供理论依据。同时，我们在血液肿瘤治疗研究领域的一系列发现，有望提高血液肿瘤的治疗效果。