Mitochondrial Membrane Dynamics in Th17 Cells

项目总结 在T细胞激活时观察到的表型和功能的广泛变化与 细胞代谢的变化。未能参与特定和适当的代谢计划可能会损害 或改变T细胞，从而导致无效的，甚至过度活跃的免疫反应。新陈代谢中心 线粒体是能量产生和生物合成活动的中心。从我们的工作 小组和其他人提供了关于线粒体新陈代谢如何对T细胞至关重要的机械性见解 分化和功能。然而，关于这些细胞器为什么会改变形状以保持 代谢、生物合成能力和功能，以及线粒体重塑是如何影响T细胞的 缺乏激活、分化或效应器分子表达。调查动态变化如何 线粒体调节代谢对CD4+T细胞的影响将加深我们对 免疫生物学以及如何在癌症、感染和其他疾病的治疗中操纵这些细胞 自身免疫力。在我们最初的实验中，我们发现与其他Th细胞亚群不同，Th17细胞是一种细胞类型 对维持肠道内环境平衡是必要的，并与某些类型的自身免疫和炎症有关， 线粒体在融合的网络中拉长，以及紧密的脊状形态。这些结果表明， 线粒体融合和OPA1蛋白的不同作用，OPA1既介导膜融合又介导脊 形态，在这些细胞中。OPA1缺失对Th1和Th2细胞分化或细胞因子无明显影响 在体外产生，虽然Th17细胞的分化也没有受到损害，但IL-17的表达显著增加 减少了。此外，T细胞特异性OPA1缺失的小鼠对发生病理改变具有抵抗力 实验性自身免疫性脑脊髓炎(EAE)--Th17细胞介导的中枢自身免疫性疾病 神经系统。最后，我们的数据揭示了肝脏激酶B1(LKB1)在调节细胞反应中的作用 对OPA1缺乏，以及在线粒体融合受到干扰时抑制Th17细胞IL-17表达。在这 我们现在试图了解线粒体动力学如何影响不同的CD4+T细胞的功能 子集。我们的总体目标是剖析OPA1在Th17细胞效应器功能中的作用，并探讨其 其他CD4+T细胞亚群的潜在作用，并确定MM融合如何与LKB1信号相互作用 在体外线粒体破坏或应激状态下调节细胞代谢以限制IL-17的表达 在活体内。为此，我们建议1)探索线粒体动力学在CD4+Th细胞中的作用，2) 确定LKB1在多大程度上控制Th17细胞对OPA1缺乏的细胞反应，以及3) 研究破坏线粒体融合后的代谢变化如何导致Th17细胞功能受抑。

PROJECT SUMMARY The extensive changes in phenotype and function observed in T cells upon activation are intimately linked to changes in cellular metabolism. The failure to engage specific and appropriate metabolic programs can impair or alter T cells, and thus lead to ineffective, or even overexuberant, immune responses. Central to metabolism are mitochondria, which serve as central hubs of energy generation and biosynthetic activity. Work from our group and others has provided mechanistic insights into how mitochondrial metabolism is critical to T cell differentiation and function. However, knowledge about why these organelles change shape to maintain metabolism, biosynthetic capacity, and function, and in what ways mitochondrial remodeling influences T cell activation, differentiation, or effector molecule expression is lacking. Investigating how dynamic changes in mitochondria regulate metabolism to impact CD4+ T cells will enhance our fundamental understanding of immunobiology and of how to manipulate these cells for disease therapy in the context of cancer, infection, and autoimmunity. In our initial experiments we found that unlike other Th cell subsets, Th17 cells, a cell type necessary for maintaining gut homeostasis and implicated in certain types of autoimmunity and inflammation, had elongated mitochondria in a fused network, as well as tight cristae morphology. These results suggested a differential role for mitochondrial fusion and the protein OPA1, which mediates both membrane fusion and cristae morphology, in these cells. OPA1 deletion had no discernible effect on Th1 and Th2 cell differentiation or cytokine production in vitro, and while Th17 cell differentiation was also unimpaired, IL-17 expression was drastically reduced. Further, mice with a T cell-specific OPA1 deletion were resistant to developing pathology in experimental autoimmune encephalomyelitis (EAE), a Th17 cell-mediated autoimmune disease of the central nervous system. Finally, our data revealed a role for liver kinase B1 (LKB1) in regulating the cellular response to OPA1-deficiency, and in restraining Th17 cell IL-17 expression when mitochondrial fusion is perturbed. In this proposal we now seek to understand how mitochondrial dynamics influence the function of diverse CD4+ T cell subsets. Our overall goal is to dissect the function of OPA1 in Th17 cell effector function, as well as probe its potential role other CD4+ T cell subsets, and to determine how MM fusion interfaces with LKB1 signaling to modulate cellular metabolism to limit IL-17 expression in settings of mitochondrial disruption or stress in vitro and in vivo. To this end, we propose to 1) explore the role of mitochondrial dynamics in CD4+ Th cells, 2) determine the extent to which LKB1 controls the cellular response to OPA1-deficiency in Th17 cells, and 3) investigate how metabolic changes upon disrupting mitochondrial fusion lead to dampened Th17 cell function.