Fine-tuning of mitochondrial Complex I activity in CD8 cells

摘要 新陈代谢是CD8T细胞免疫应答的关键因素。线粒体新陈代谢对于 CD8细胞的效应功能。因此，可以使用增强线粒体呼吸的策略来改善 CD8细胞免疫应答的疗效。然而，虽然有许多药理试剂 抑制电子传递链的不同步骤和/或合成线粒体ATP，增强 线粒体的活动并不容易。我们最近发现了MCJ(甲基化控制的J蛋白)，也 称为Dna JC15)作为复合体I和线粒体呼吸的内源性负调节因子。我们有 结果表明，失去MCJ会导致复合体I活性、线粒体膜电位、线粒体呼吸和ATP水平的增加 在CD8细胞中。MCJ缺失引起的线粒体呼吸增加也促进了细胞因子的分泌 作为细胞毒活性。因此，发现MCJ如何与复杂的I相互作用以及它是如何被调控的可能会带来新的 破坏这种新陈代谢刹车的策略。MCJ(N-MCJ)的N-末端区域与已知的没有同源性 真核蛋白，但它保留了仅存在于不同来源的细菌蛋白中的特定序列 甲型变态杆菌属。有趣的是，这些细菌蛋白具有氧化还原酶活性，类似于 复合型NADH脱氢酶。N-MCJ与NDUFv1相互作用，NDUFv1是复合体I的亚单位，包含 NADH脱氢酶活性，将NADH氧化为NAD+。我们最近的计算分析和 质谱分析表明N-MCJ能与NAD+结合。我们提出了一个模型，其中MCJ扮演着一个动态的角色 以NAD+为传感器的络合物I的负性调节剂。当活动的NAD+水平产生时 复合体I升高，NAD+与N-MCJ结合。NAD+与N-MCJ的结合引起结构变化 这使得N-MCJ可以与NDUFv1交互，并向复合体I到TO提供负反馈 减弱其活性，避免过量消耗有限的代谢底物。我们将调查：1) NAD+与N-MCJ的结合及其对N-MCJ构象变化的影响2)NAD+与N-MCJ的动态相互作用 N-MCJ与NDUFv1的结合，NAD+对其微调以及对线粒体呼吸的影响。来自这些的结果 研究可能导致开发新的策略和机制来安全地增加线粒体 CD8细胞的呼吸和增强免疫反应。

SUMMARY Metabolism is a key factor for CD8 T cell immune response. Mitochondria metabolism is essential for effector function of CD8 cells. Thus, strategies to enhance mitochondrial respiration could be used to improve efficacy of CD8 cell immune response. However, while there are a number of pharmacological reagents inhibiting different steps of the electron transport chain and/or synthesis mitochondrial ATP, enhancing mitochondrial activity is not easy. We have recently identified MCJ (Methylation-Controlled J protein, also called DnaJC15) as an endogenous negative regulator of Complex I and mitochondrial respiration. We have shown that loss of MCJ results in increased Complex I activity, MMP, mitochondrial respiration and ATP levels in CD8 cells. Increased mitochondrial respiration caused by loss of MCJ enhances cytokine secretion as well as cytotoxic activity. Thus, finding how MCJ interacts with Complex I and how it is regulated could lead to new strategies to disrupt this metabolic brake. The N-terminal region of MCJ (N-MCJ) has no homology to known eukaryotic proteins, but it retains specific sequence present only in bacterial proteins from different Alphaproteobacteria species. Interestingly, those bacterial proteins have an oxidoreductase activity, similarly to Complex I NADH dehydrogenase. N-MCJ interacts with NDUFv1, the subunit of Complex I that contains the NADH dehydrogenase activity to oxidize NADH to NAD+. Our recent computational analysis together with mass spectrometry suggest that N-MCJ can bind NAD+. We propose a model where MCJ acts as a dynamic negative regulator of Complex I with NAD+ as a sensor. When NAD+ levels produced by an active Complex I are elevated, NAD+ binds N-MCJ. Binding of NAD+ to N-MCJ then causes a structural change that makes N-MCJ accessible to interact with NDUFv1, and provide a negative feedback to Complex I to attenuate its activity and avoid overconsumption of limited metabolic substrates. We will investigate: 1) The binding of NAD+ to N-MCJ and its effect on N-MCJ conformational changes; 2) The dynamic interaction of N-MCJ with NDUFv1, its fine-tuning by NAD+ and the impact in mitochondrial respiration. Results from these studies could lead to the development of novel strategies and mechanisms to safely increase mitochondrial respiration in CD8 cells and enhance immune responses.