Cell-based and multi-omics profiling reveal dynamic metabolic repurposing of mitochondria to drive developmental progression of Trypanosoma brucei

Mitochondrial metabolic remodeling is a hallmark of the Trypanosoma brucei digenetic life cycle since the insect stage utilizes the cost-effective oxidative phosphorylation to generate ATP, while bloodstream cells switch to less energetically efficient aerobic glycolysis. Due to difficulties in acquiring enough parasites from the tsetse fly vector for biochemical analysis, the dynamics of the parasite´s mitochondrial metabolic rewiring in the vector have remained obscure. Here, we took advantage of in vitro-induced differentiation to follow changes at the RNA, protein and metabolite levels. This multi-omics and cell-based profiling showed an immediate redirection of electron flow from the cytochrome mediated pathway to a mitochondrial alternative oxidase, an increase in proline consumption and its oxidation, elevated activity of complex II and certain TCA cycle enzymes, which led to mitochondrial inner membrane hyperpolarization and increased ROS levels in both mitochondrion and cytosol. Interestingly, these ROS molecules acted as signaling molecules driving developmental progression since exogenous expression of catalase, a ROS scavenger, halted the in vitro-induced cell differentiation. Our results provide insights into the mechanisms of the parasite´s mitochondrial rewiring and reinforce the emerging concept that mitochondria act as signaling organelles through release of ROS to drive cellular differentiation.

Data availability:
RNA-Seq
Proteomic data associated with this study are available in the PRIDE repository: accession number PXD016370.

线粒体代谢重塑是布氏锥虫（Trypanosoma brucei）复殖生命周期的标志性特征，因其昆虫宿主阶段利用经济高效的氧化磷酸化生成三磷酸腺苷（ATP），而血液阶段的虫体则切换至能量效率更低的有氧糖酵解。由于难以从采采蝇媒介中获取足够数量的寄生虫用于生化分析，该媒介中寄生虫的线粒体代谢重编程动态仍未明晰。本研究借助体外诱导分化模型，追踪了RNA、蛋白质及代谢物水平的变化。这项多组学结合细胞水平谱分析的研究显示，电子流从细胞色素介导的通路即刻转向线粒体交替氧化酶，脯氨酸的消耗与氧化水平升高，线粒体呼吸链复合体II及部分三羧酸循环酶的活性增强，最终导致线粒体内膜超极化，并在线粒体与细胞质基质中均出现活性氧（ROS）水平升高的现象。有趣的是，这些活性氧分子充当了信号分子以推动发育进程：外源表达过氧化氢酶——一种活性氧清除剂——可阻断体外诱导的细胞分化。本研究结果揭示了寄生虫线粒体重编程的机制，并佐证了新兴观点：线粒体可通过释放活性氧作为信号细胞器，驱动细胞分化。

数据可用性：
RNA测序（RNA-Seq）
本研究相关的蛋白质组学数据已存入PRIDE数据库，登录号为PXD016370。