Exploring the mitochondrial phosphoproteome during metabolic stress

线粒体将营养物质中的大部分能量转化为三磷酸腺苷，三磷酸腺苷是完成所有需要能量的细胞生化过程所必需的。因此，需要对线粒体代谢进行严格的调控，以维持细胞在代谢应激期间的存活。例如，线粒体的ATP产量需要在营养供应不足时保持，而必须在运动期间增加，以匹配细胞的能量需求。近年来，激酶作为线粒体功能的重要调节因子出现。这些酶通过添加磷酸基团来改变蛋白质的性质。虽然我们知道几种激酶可以定位在线粒体中，它们可以靶向不同的蛋白质，但对于它们在具有挑战性的代谢条件下调节线粒体新陈代谢的重要性还知之甚少。有趣的是，在这种情况下，受影响的几种代谢副产物可以激活酶的活性。由于线粒体是这些代谢物的关键调节者，在代谢应激过程中，位于线粒体内的激酶可以代表直接的信使来调节线粒体的代谢。 这项拟议的研究计划旨在确定线粒体磷酸化事件在调整线粒体功能以应对代谢应激中的重要性。这项建议的第一个目标是确定关键代谢物(活性氧、钙和三磷酸腺苷)的线粒体水平如何调节线粒体磷酸蛋白质组，而第二个目标是确定线粒体磷酸蛋白质组在禁食和运动过程中是如何调节的。这些事件所针对的线粒体蛋白将被识别出来。然后，模拟这些磷酸化事件的突变蛋白的产生将使我们能够了解这些过程对线粒体新陈代谢的功能影响。第三个目标是确定在代谢应激反应中发生的磷酸化过程中涉及的激酶。 在全球范围内，这项研究计划将确定新的线粒体内生化级联，从而能够调整新陈代谢，以应对具有挑战性的代谢条件。大多数野生动物面临持续的新陈代谢压力。例如，这种动物可以长时间不进食和/或不得不远距离迁徙。因此，这项研究计划最终将确定影响特定物种适应其环境生态位的新分子机制。由于线粒体功能缺陷可能导致不同的病理，包括糖尿病、癌症和神经退行性疾病，这项拟议的工作将对开发指示细胞、组织和整个个人的“健康”状态的新工具具有很高的兴趣。

Mitochondria convert most of the energy contained in nutrients into ATP, which is required to perform all cellular biochemical processes needing energy. Therefore, the mitochondrial metabolism needs to be tightly regulated to maintain survival of cells during metabolic stress. For instance, the mitochondrial ATP production needs to be maintained during low nutrient availability whereas it must be increased during exercise to match the energetic needs of cells. Kinases emerged recently as important regulators of mitochondrial functions. These enzymes change the properties of proteins by adding a phosphate group. Although we know that several kinases can be localized in mitochondria where they can target different proteins, little is known about their importance in the regulation of the mitochondrial metabolism during challenging metabolic conditions. Interestingly, the activity of kinases can be activated by several sub-products of the metabolism which are affected in such conditions. Since mitochondria are key regulators of these metabolites, kinases localized within mitochondria could represent direct messengers to regulate the mitochondrial metabolism during metabolic stress. The proposed research program aims to determine the importance of mitochondrial phosphorylation events in the adjustment of mitochondrial functions in response to metabolic stress. The first objective of this proposal is to determine how mitochondrial levels of key metabolites (reactive oxygen species, calcium and ATP) modulate the mitochondrial phosphoproteome, whereas the second objective is to determine how the mitochondrial phosphoproteome is modulated during fasting and exercise. The mitochondrial proteins targeted by these events will be identified. Then, the generation of mutant proteins mimicking these phosphorylation events will enable to understand the functional impact of these processes on the mitochondrial metabolism. The third objective is to identify the kinases involved in the phosphorylation processes occurring in response to metabolic stress. Globally, this research program will identify new intra-mitochondrial biochemical cascades enabling the adjustment of metabolism in response to challenging metabolic conditions. Most wild animals face persistent metabolic stress. For instance, such animals can stay long periods without eating and/or have to migrate for long distances. Therefore, this research program will eventually identify new molecular mechanisms impacting the adaptation of a given species to its environmental niche. Since defects in mitochondrial functions can lead to different pathologies, including diabetes, cancer and neurodegenerative diseases, this proposed work will be of high interest for the development of new tools indicative of the “health” status of cells, tissues and entire individuals.