基于空间代谢组学考察醛糖还原酶促进肝癌发生发展的代谢模式

The polyol pathway is a two-step process that converts glucose to fructose, consuming NADPH and yielding NADH. In our previous work, we found that the overexpression of first rate-limiting enzyme aldose reductase (AR) of the polyol pathway in the liver of mice can induce non-alcoholic fatty liver disease (NAFLD) after 14-week feeding with glucose water. The mice with AR overexpression treated with glucose water and diethylnitrosamine (DEN) would promote hepatocarcinogenesis much severer compared with wildtype group. We also found that AR overexpression suppresses LKB1-AMPK signaling pathway while upregulates glutaminolysis in the liver. To figure out the metabolic patterns in AR-promoted hepatocarcinogenesis by spatiotemporal analysis, we will develop spatial metabolomics technologies. Firstly, we will develop metabolic flux analysis in vivo for understanding the underlying mechanism in which AR overexpression promotes fatty acid and cholesterol biosynthesis bypassing glycolysis, and regulates glutamine metabolism for NADPH production. Secondly, since AR senses glucose and glucose concentrations would be heterogeneous in the liver, we suspected that AR senses glucose for metabolic heterogeneity. In this regard, we will perform the quantitative analysis of fatty acids and bile acids in tiny samples and the spatial reconstruction for mapping the fatty acids and bile acids with liver zonation. Thirdly, to further interrogate the metabolic mechanism by AR-LKB1-AMPK axis, we will develop spatial metabolic fluxomics for investigating glutamine metabolism as well as the production, transformation and re-equilibrium of NADPH and NADH at the subcellular level. Taken together, we focused on AR-mediated fructose metabolism as well as related metabolic network during hepatocelluar carcinoma development, and raised the scientific questions for developing spatial metabolomics and metabolic fluxomics, which might promote the development of a new research direction: compartmentalization of metabolic features.

葡萄糖经由多元醇旁路转化为果糖，同时消耗NADPH产生NADH，但氧化还原再平衡尚不清晰。前期发现小鼠肝脏里过表达多元醇旁路的醛糖还原酶（AR）对果糖累积引起的肝病变可能起作用，即喂养葡萄糖水可诱发脂肪肝，辅以二乙基亚硝胺较易诱导肝癌。过表达AR可抑制LKB1-AMPK通路且上调谷氨酰胺氧化代谢。为了从时空维度探究AR促进肝癌发生发展的代谢网络波动，拟开发空间代谢组学方法，包括：一、为明确AR绕过糖酵解大部分调节步骤促进肝癌发生发展的重编程机制，拟开展体内代谢流分析；二、为理解AR感应肝脏葡萄糖促进区域代谢异质性，拟开展脂肪酸、胆汁酸定量分析和空间重构；三、为探究AR-LKB1-AMPK轴调控谷氨酰胺代谢的机制，拟从亚细胞水平开展空间代谢流分析，考察谷氨酰胺对氧化还原再平衡的贡献。本项目以肝癌发生发展中的果糖代谢及相关网络为切入点，开发空间代谢（流）组学方法，助推代谢特征区域化新研究方向。

在基金委重大研究计划的培育项目支持下，围绕代谢，特别是糖脂代谢为主题，主导或参与多个项目的研究，取得了较为丰硕的成果。目前已经主导或参与发表研究论文16篇，投稿中的研究论文和综述文章也达6篇，预计共有22篇文章标注该基金号。同时正在申报的专利2项，并有一项发明专利将在近日提交，预计共申报3项发明专利及实用新型专利。这些研究成果都充分发挥了代谢组学、脂质组学或代谢流分析技术，并有部分工作较为深入地揭示病理生理条件下的代谢调控机制。这些工作主要包括：鉴定新冠肺炎的代谢标志物及其调控作用（PNAS 2022, 最后通讯；Signal Transduction and Targeted Therapy 2020，共同通讯）。在肺癌研究中，我们揭示SLC1A1可以作为谷氨酸转运体促进谷氨酸摄取，用于还原型谷胱甘肽的合成，同时由于消耗细胞外的谷氨酸而促进胱氨酸的摄取，更有助于还原型谷胱甘肽的合成而促进肺癌发生发展（Cancer Research 2021，共同通讯）。我们还发现溶瘤病毒在肺癌细胞中的代谢调节机制，是通过线粒体自噬以及SLC1A3介导的谷氨酰胺分解代谢等方式（Autophagy 2022，共同通讯；Virulence 2022，共同通讯）。除了溶瘤病毒，我们也证实了工程细菌抑制癌细胞转移的免疫代谢机制是通过激活自然杀伤细胞实现的（Nature Communications 2021，共同通讯）。而在免疫代谢研究中，我们还发现T细胞特异性蛋白THEMIS在CD8+ T细胞中通过Jak-Stat和mTOR信号调控糖代谢与核苷酸合成通路介导CD8+ T细胞的增殖（Science Signaling 2022，共同通讯）。在该项目支持下，这些研究成果体现了代谢对机体健康的重要性。特别是小分子代谢物的功能依然是冰山一角，值得更加广泛深入地研究。比如在新冠康复者携带抗体或抗体消退者的代谢差异分析中，我们发现甘氨酰脯氨酸在新冠康复但抗体消退者的血浆中显著累积，随后研究发现甘氨酰脯氨酸可以调节免疫细胞亚群和新冠抗体的水平。对于2糖尿病患者而言，接种新冠疫苗后，使用二肽基肽酶4抑制剂西格列汀，不仅可以治疗2型糖尿病，还可以通过下调甘氨酰脯氨酸水平而维持较高的新冠抗体水平，一举两得。综上所述，我们以项目的科学问题为导向，有针对性开发和运用代谢组学新技术，应用于病理生理机制研究。