PCK-1介导的糖原代谢调控CD8+记忆性T细胞形成和维持的研究

It is of great significance to explore the mechanism of memory formation and maintenance of CD8 memory T cells in order to understand the anti-tumor, anti-infection and clinical application of T cells. Studies have shown that memory T cells rely on fatty acid beta oxidation, to achieve its special metabolic patterns. However, whether other intrinsic metabolic pathways affect the formation and maintenance of memory T cell remains elusive. Our preliminary study found that CD8+memory T cells express higher level of cytoplasmic phosphoenolpyruvate carboxykinase (PCK1, rate limiting enzyme of gluconeogenesis pathway) and glycogen than the initial T cells and effector T cells, suggesting that gluconeogenesis and glycogen metabolism pathway may be related to CD8 memory T cells. Based on this, we will investigate the role of PCK1-mediated glycogen metabolism and its branching pathway in the formation and maintenance of CD8+memory T cells by in vivo and in vitro models in this project. From the perspective of gluconeogenesis and glycogen metabolism, this project will explore the memory formation and maintenance of CD8+memory T cells, which not only answering the basic theoretical problems of immunology, but also has good practical application value. The completion of this project is expected to explain the mechanism of the formation and maintenance of CD8 memory T cells, and provide the basis for immunotherapy of T cells.

探究CD8+记忆性T细胞记忆形成与维持的机理，对于理解机体抗肿瘤、抗感染以及T细胞临床应用具有重大意义。已有研究显示，记忆性T细胞依赖脂肪酸β氧化，实现其特殊代谢模式，然而其它代谢模式是否亦影响T细胞记忆形成与维持，尚不清楚。申请人前期研究发现，CD8+记忆性T细胞的胞浆型磷酸烯醇式丙酮酸羧激酶（PCK1, 糖异生关键限速酶）及糖原的表达显著高于初始及效应性T细胞，提示糖异生及糖原代谢途径可能与CD8+记忆性T细胞相关。基于此，本项目拟采用体内及体外模型，探究PCK1介导的糖异生途径、以及由糖异生转向糖原代谢途径在CD8+记忆性T细胞的生成与维持中的作用。从糖异生及糖原代谢这一全新角度，探究记忆性CD8+T细胞的记忆形成与维持，不仅回答免疫学的基本理论性问题，而且具有很好的实际应用价值。本课题的完成有望阐述CD8+记忆性T细胞生成及维持的新机制，为肿瘤的T细胞免疫治疗提供基础。

细胞代谢对CD8+ T细胞记忆形成与维持具有重要的调节作用。糖原在功能上一直被认为是能量代谢的产物。我们的研究表明，糖异生关键酶Pck1（胞浆型磷酸烯醇丙酮酸羧激酶）能够调控CD8+记忆性T细胞（CD8+Tm）糖原合成。合成的糖原经分解后又生成6-磷酸葡萄糖，而此时的6-磷酸葡萄糖则进入磷酸戊糖途径，从而产生还原型NADPH，维持高水平的还原性谷胱甘肽，及时将细胞内的自由基给予清除，从而维持记忆性T 细胞的长期存活。机制上，我们发现CD8+Tm细胞具有活跃的酮体代谢，酮体代谢产生的BHB在CD8 Tm细胞中高表达，通过β-羟基丁酸修饰组蛋白H3K9，从而上调FoxO1和PGC1α基因的表达。结果，FoxO1和PGC-1α协同上调Pck1的表达，从而引导碳流沿着糖异生途径流向糖原和磷酸戊糖途径。这些结果揭示了在CD8 Tm细胞中，酮体生成是一种不寻常的代谢途径，连接了CD8 Tm细胞发育所需的表观遗传修饰。