Mitochondrial dynamics in the regulation of mitochondrial function and oxidative phosphorylation

众所周知，线粒体是细胞的能量制造者。这些动态细胞器可以通过线粒体融合蛋白MFN和OPA1以及分裂蛋白Drp1改变其分裂和融合活性来改变其结构。线粒体具有根据生理需求不断修改其结构的能力，最近的发现表明线粒体结构和功能之间存在直接联系。例如，我们已经证明，在特定条件下，线粒体结构的变化可以改变能量代谢，促进有效的ATP产生，同时减少活性氧物种(ROS)。在分子水平上，线粒体的效率是通过增强电子传递链(ETC)复合体(称为呼吸超复合体)的相互组装来调节的。然而，线粒体动力学变化如何调控氧化磷酸化的分子机制尚不清楚。这一建议的目的是揭示线粒体代谢的基本分子机制以及线粒体动力学是如何调节这一机制的。我们最近发现，线粒体形成GTP酶蛋白OPA1可以通过促进电子传输链(ETC)复合体(C1-C1V)组装成呼吸超复合体来决定细胞的生物能量状态和线粒体的呼吸能力。调控线粒体动力学的OPA1可以促进超复合体的组装，从而提高OXPHOS的效率，减少破坏性ROS的产生。这一数据首次证明线粒体成形蛋白在调控线粒体OXPHOS中起着直接作用。为了确定OPA1调节超复合体组装的潜在机制，我们使用基于SILAC的定量质谱学(MS)技术进行了蛋白质组筛选。这已经发现了几个候选蛋白质，包括ETC复合体I组装因子Cox7RP，它们可能介导OPA1对新陈代谢施加的分子变化。Cox7RP促进ETC超复合体的组装并调节能量代谢，我们的初步数据表明，Cox7RP水平对线粒体OPA1表达的变化做出反应。因此，我们假设线粒体形态可以通过线粒体形成蛋白OPA1与Cox7RP的相互作用来调节OXPHOS。因此，将研究Cox7RP和线粒体形成蛋白OPA1之间的功能相互作用，以了解线粒体形态和细胞生物能量状态之间的联系。

Mitochondria are classically known to be the cellular energy producers. These dynamic organelles can modify their structure by alterations in their fission and fusion activities through the mitochondrial fusion proteins MFN and OPA1, and fission protein DRP1. Mitochondria have the ability to constantly modify their architecture in response to physiological demands and recent discoveries have shown a direct link between mitochondrial structure and function. For example, we have shown that changes in mitochondrial structure, under certain conditions, can modify energy metabolism to promote efficient ATP production while reducing reactive oxygen species (ROS). At the molecular level, the efficiency of mitochondria is modified through enhanced inter-assembly of electron transport chain (ETC) complexes (known as respiratory supercomplexes). However, the molecular mechanism of how changes in mitochondrial dynamics can regulate oxidative phosphorylation is still unknown. The purpose of this proposal is to uncover the basic molecular mechanism of mitochondrial metabolism and how this is regulated by mitochondrial dynamics.******We have recently uncovered that the mitochondrial-shaping GTPase protein OPA1 can dictate the bioenergetic status of cells and mitochondrial respiratory capacity by promoting assembly of the electron transport chain (ETC) complexes (C1-C1V) into respiratory super complexes. Manipulation of OPA1, which regulates mitochondrial dynamics, can promote supercomplex assembly to enhance the efficiency of OXPHOS and reduce the generation of damaging ROS. This data provides the first evidence that mitochondrial shaping proteins play a direct role in regulating mitochondrial OXPHOS. In order to identify potential mechanisms by which OPA1 can regulate supercomplex assembly we have performed a proteomic screen using a SILACbased quantitative mass spectrometry (MS) technique. This has uncovered several candidate proteins, including the ETC Complex I assembly factor Cox7RP, that may mediate the molecular changes that OPA1 imposes on metabolism. Cox7RP promotes ETC supercomplex assembly and regulates energy metabolism, and our preliminary data shows that levels Cox7RP respond to changes in expression of mitochondrial OPA1. Therefore, we hypothesis that mitochondrial morphology can regulate OXPHOS through the interaction of the mitochondrial shaping protein OPA1 with Cox7RP. Thus the functional interaction between Cox7RP and the mitochondrial shaping protein OPA1 will be studied to understand the link between mitochondrial morphology and cellular bioenergetic states.