Mitochondrial dynamics: regulation mechanisms and physiologic impact.

线粒体的形态状态与能量产生、细胞健康和细胞凋亡有关。线粒体的形状被广泛归因于线粒体分裂和融合之间的平衡。然而，人们没有意识到它们是形态上柔韧的细胞器，可以在不经历分裂的情况下改变形状。它们表现出可逆的“圆化”，导致细胞器变短，这一过程我们称之为重塑。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。中心论题是线粒体重塑是调控线粒体形态和细胞内稳态的关键过程。 我们之前由NSERC资助的研究首次对线粒体分裂和重塑进行了定量区分。我们报道了在钙诱导的线粒体形态改变中，线粒体重塑是主要过程。我们还证明了对这些过程的调节在机制上是不同的；钙调神经磷酸酶抑制剂可以阻止分裂，但不能阻止重塑。这一机制上的区别得到了我们的论文的支持，我们在论文中表明，抗氧化剂阻止的是重塑，而不是分裂。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特定作用来扩展这些发现。 具体目标： 研究线粒体重塑的分子机制。我们以前已经证明，细胞内钙、ROS和分子马达都参与调节线粒体的运动，在通过重塑调节线粒体形态方面发挥关键作用。我们的初步数据表明GSK3参与了重塑的机制。ROS信号调节重塑的具体机制将通过评估氧化信号诱导重塑的蛋白质靶标和检测GSK3的作用来研究。 检查线粒体重塑对细胞的影响。正如我们之前报道的那样，线粒体重塑将被诱导，或者由GSK3抑制剂诱导。我们将研究细胞和线粒体重塑的影响，特别是ATP的产生，ROS的产生，钙的稳态，对线粒体内外膜的影响，以及对冠状突起的影响。 研究线粒体重塑在有丝分裂中的作用。 我们假设重塑是线粒体有丝分裂的一个关键的初始事件。通过选择性地诱导或阻断线粒体重塑，我们将研究线粒体重塑与细胞器循环的关系。这些实验将深入了解线粒体重塑和线粒体动力学调控的功能重要性。

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 GSK3 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 GSK3. II. Examine the cellular impact of mitochondrial remodelling. Mitochondrial remodelling will be induced as we have reported previously or by the GSK3 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.