data_sheet_1_Rotenone Treatment Reveals a Role for Electron Transport Complex I in the Subcellular Localization of Key Transcriptional Regulators During T Helper Cell Differentiation.PDF

Recent advances in our understanding of tumor cell mitochondrial metabolism suggest it may be an attractive therapeutic target. Mitochondria are central hubs of metabolism that provide energy during the differentiation and maintenance of immune cell phenotypes. Mitochondrial membranes harbor several enzyme complexes that are involved in the process of oxidative phosphorylation, which takes place during energy production. Data suggest that, among these enzyme complexes, deficiencies in electron transport complex I may differentially affect immune responses and may contribute to the pathophysiology of several immunological conditions. Once activated by T cell receptor signaling, along with co-stimulation through CD28, CD4 T cells utilize mitochondrial energy to differentiate into distinct T helper (Th) subsets. T cell signaling activates Notch1, which is cleaved from the plasma membrane to generate its intracellular form (N1ICD). In the presence of specific cytokines, Notch1 regulates gene transcription related to cell fate to modulate CD4 Th type 1, Th2, Th17, and induced regulatory T cell (iTreg) differentiation. The process of differentiating into any of these subsets requires metabolic energy, provided by the mitochondria. We hypothesized that the requirement for mitochondrial metabolism varies between different Th subsets and may intersect with Notch1 signaling. We used the organic pesticide rotenone, a well-described complex I inhibitor, to assess how compromised mitochondrial integrity impacts CD4 T cell differentiation into Th1, Th2, Th17, and iTreg cells. We also investigated how Notch1 localization and downstream transcriptional capabilities regulation may be altered in each subset following rotenone treatment. Our data suggest that mitochondrial integrity impacts each of these Th subsets differently, through its influence on Notch1 subcellular localization. Our work further supports the notion that altered immune responses can result from complex I inhibition. Therefore, understanding how mitochondrial inhibitors affect immune responses may help to inform therapeutic approaches to cancer treatment.

近年来，随着我们对肿瘤细胞线粒体代谢认知的不断深入，该代谢通路或可成为极具吸引力的治疗靶点。线粒体（Mitochondria）是代谢的核心枢纽，在免疫细胞表型的分化与维持过程中为细胞提供能量。线粒体膜包含多种参与氧化磷酸化过程的酶复合体，而氧化磷酸化正是细胞能量产生的核心途径。研究数据表明，在这类酶复合体中，电子传递复合物I（Complex I）的功能缺陷可对免疫应答产生差异性影响，并可能参与多种免疫相关疾病的病理生理进程。当CD4⁺ T细胞通过T细胞受体（T cell receptor）信号通路激活，并伴随CD28介导的共刺激信号时，会借助线粒体提供的能量分化为不同的辅助性T细胞（Th）亚群。T细胞信号通路可激活Notch1蛋白，该蛋白从细胞膜被切割后会生成其胞内活性形式N1ICD。在特定细胞因子存在的条件下，Notch1可调控与细胞命运相关的基因转录，进而调节CD4⁺ T细胞向Th1、Th2、Th17以及诱导性调节性T细胞（iTreg）的分化。上述任一亚群的分化过程，均依赖线粒体提供的代谢能量。我们提出假说：不同Th亚群对线粒体代谢的需求存在差异，且这一调控过程可能与Notch1信号通路存在交叉互作。我们采用经典的复合物I抑制剂——有机农药鱼藤酮（rotenone），以评估线粒体完整性受损对CD4⁺ T细胞向Th1、Th2、Th17及iTreg细胞分化的影响。此外，我们还探究了经鱼藤酮处理后，各Th亚群中Notch1的定位及其下游转录调控功能会发生何种改变。我们的研究数据表明，线粒体完整性可通过影响Notch1的亚细胞定位，对各Th亚群产生差异化调控。本研究进一步支持了“电子传递复合物I抑制可引发免疫应答异常”这一学术观点。因此，阐明线粒体抑制剂对免疫应答的调控机制，可为癌症治疗的相关疗法提供理论参考依据。