Mitochondrial dynamics: regulation mechanisms and physiologic impact.

线粒体动力学：调节机制和生理影响。

• 批准号: RGPIN-2017-06498
• 负责人: Rintoul, Gordon
• 金额: $ 1.89万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=663384
• 关键词: Mitochondrial; dynamics; regulation; mechanisms; physiologic

The morphological state of mitochondria has been linked to energy production, cell health and apoptosis. Mitochondrial shape is widely ascribed to a balance between mitochondrial fission and fusion. However it is underappreciated that they are morphologically pliable organelles that change their shape without undergoing fission. They exhibit reversible "rounding", which results in shorter organelles, a process we refer to as remodelling. We will explore the regulatory mechanisms and functional significance of mitochondrial remodelling in astrocytes. The central thesis is that mitochondrial remodelling is a critical process in the regulation of mitochondrial morphology and therefore cellular homeostasis.***Our previous NSERC funded research was the first to quantitatively differentiate between mitochondrial fission and remodelling. We reported that mitochondrial remodelling is the predominant process in calcium-induced mitochondrial shape-change. We also demonstrated that regulation of the processes are mechanistically distinct; fission, but not remodelling is blocked by calcineurin inhibitors. This mechanistic distinction is supported by our paper in which we show that remodelling, not fission, is blocked by antioxidants. The current proposal extends these findings by examining the specific impact of remodelling on cellular physiology, exploring the mechanisms of remodelling, and examining the specific role of remodelling in mitochondrial quality control.***Specific objectives:***I. Investigate the molecular mechanisms of mitochondrial remodelling. We have shown previously that intracellular calcium, ROS, and molecular motors, all implicated in modulating mitochondrial motility, have critical roles in regulating mitochondrial morphology through remodelling. Our preliminary data implicates GSK3β in the mechanism of remodelling. The specific mechanisms by which ROS signalling regulates remodelling will be examined by assessing the protein targets of oxidative signalling induced remodelling and examining the role of GSK3β. ***II. Examine the cellular impact of mitochondrial remodelling. Mitochondrial remodelling will be induced as we have reported previously or by the GSK3β inhibitor. We will examine the cellular and mitochondrial impact of remodelling; specifically ATP production, ROS generation, calcium homeostasis, the impact on the mitochondrial inner and outer membranes, as well as the effect on the cristae. ***III. Investigate the role of mitochondrial remodelling in mitophagy. ***We hypothesise that remodelling is a key initial event in mitochondrial mitophagy. By selectively inducing or blocking mitochondrial remodelling, we will investigate the relationship between remodelling and organelle recycling. These experiments will yield insights into the functional importance of mitochondrial remodelling and regulation of mitochondrial dynamics.

线粒体的形态状态与能量产生、细胞健康和细胞凋亡有关。线粒体形状被广泛归因于线粒体裂变和融合之间的平衡。然而，人们低估了它们是形态上柔韧的细胞器，可以在不发生裂变的情况下改变形状。它们表现出可逆的“舍入”，从而导致细胞器变短，我们将这个过程称为重塑。我们将探讨星形胶质细胞线粒体重塑的调控机制和功能意义。中心论点是线粒体重塑是线粒体形态调节和细胞稳态调节的关键过程。***我们之前 NSERC 资助的研究是第一个定量区分线粒体裂变和重塑的研究。 我们报道线粒体重塑是钙诱导线粒体形状变化的主要过程。我们还证明了过程的调节在机制上是不同的；钙调神经磷酸酶抑制剂会阻止裂变，但不会阻止重塑。我们的论文支持了这种机制上的区别，其中我们表明，抗氧化剂阻止的是重塑，而不是裂变。目前的提案通过检查重塑对细胞生理学的具体影响、探索重塑的机制以及检查重塑在线粒体质量控制中的具体作用来扩展这些发现。***具体目标：***I。 研究线粒体重塑的分子机制。 我们之前已经证明，细胞内钙、ROS 和分子马达都与调节线粒体运动有关，在通过重塑调节线粒体形态方面发挥着关键作用。我们的初步数据表明 GSK3β 参与了重塑机制。通过评估氧化信号传导诱导重塑的蛋白质靶标并检查 GSK3β 的作用，将检查 ROS 信号传导调节重塑的具体机制。 ***二.检查线粒体重塑的细胞影响。 正如我们之前报道的那样或由 GSK3β 抑制剂诱导线粒体重塑。我们将研究重塑对细胞和线粒体的影响；特别是 ATP 产生、ROS 产生、钙稳态、对线粒体内膜和外膜的影响以及对嵴的影响。 *** 三.研究线粒体重塑在线粒体自噬中的作用。 ***我们假设重塑是线粒体线粒体自噬的关键初始事件。通过选择性诱导或阻断线粒体重塑，我们将研究重塑与细胞器回收之间的关系。这些实验将深入了解线粒体重塑和线粒体动力学调节的功能重要性。