Regulation of Mitochondrial Division by Phosphatidic Acid

摘要 线粒体是真核细胞中普遍存在的细胞器，在能量生产中发挥着重要作用， 代谢、信号转导和细胞死亡。这些功能需要精确控制线粒体 线粒体分裂的改变与许多神经系统疾病有关。一种关键蛋白质 参与线粒体分裂的是动力蛋白相关蛋白1(Drp1)，这是一种机械力化学GTP酶，它 构成线粒体分裂机制。Drp1是一种可溶性蛋白质，从线粒体中招募到线粒体 胞浆中的Drp1受体蛋白定位于线粒体上。在被招募后，Drp1聚合成更高的- 订购齐聚物。然后，drp1寡聚体驱动线粒体的收缩。在教科书模型中， 当Drp1被招募并寡聚到线粒体上时，线粒体分裂受到调控。 与目前的这种观点相反，我们最近的工作提出了一种主要机制，通过这种机制， 线粒体上的Drp1寡聚后，收缩受到调节。这一新机制涉及到新的 Drp1与信号转导的磷脂磷脂酸(PA)及饱和磷脂的相互作用 在线粒体外膜上。我们认为这些脂质相互作用抑制了GTP酶的活性。 Drp1低聚体，从而控制膜收缩的启动。此外，我们发现一个 线粒体，产生PA的磷脂酶D，MitoPLD，直接结合Drp1并抑制线粒体分裂。 这一结果表明PA是在除法机械附近局部产生的。这是当地生产的PA 可能确保Drp1的强大空间调控。这些发现导致了一种假设，即PA抑制Drp1和 Drp1从MitoPLD上解离后激活线粒体分裂。 在这项拟议的研究中，我们将批判性地检验这一假设，并在知情的情况下进一步发展和调整它 道路。在目标1中，我们将确定PA如何使用创新的生化、生物物理和 细胞分析。我们还将分析线粒体脂质成分在分裂过程中的变化 脂质组学。在目标2中，我们将破译Drp1-MitoPLD相互作用如何调节Drp1和 线粒体分裂中的MitoPLD以及Drp1-MitoPLD相互作用是如何调控的。我们还将确定 MitoPLD如何控制线粒体中的脂质成分。我们期待这一提议的结果 研究将极大地推进重要的磷脂生物学和细胞器的动力学和产生 对人类健康和疾病的批判性见解。

Abstract Mitochondria are ubiquitous organelles in eukaryotic cells that play important roles in energy production, metabolism, signal transduction and cell death. These functions require precise control of mitochondrial division, and altered mitochondrial division has been linked to many neurological diseases. A key protein involved in mitochondrial division is dynamin-related protein 1 (Drp1), a mechano-chemical GTPase that constitutes the mitochondrial division machinery. Drp1 is a soluble protein recruited to mitochondria from the cytosol by Drp1 receptor proteins located on mitochondria. After being recruited, Drp1 polymerizes into higher- order oligomers. Drp1 oligomers then drive the constriction of mitochondria. In the textbook model, mitochondrial division is regulated when Drp1 is recruited and oligomerized onto mitochondria. In contrast to this current view, our recent work suggested a major mechanism by which the timing of the constriction is regulated after Drp1 is oligomerized on mitochondria. This new mechanism involves novel interactions of Drp1 with the signaling phospholipid phosphatidic acid (PA) along with saturated phospholipids in the mitochondrial outer membrane. We suggest that these lipid interactions inhibit the GTPase activity of Drp1 oligomers and thereby control the initiation of the membrane constriction. In addition, we found that a mitochondrial, PA-producing phospholipase D, MitoPLD, directly binds Drp1 and inhibits mitochondrial division. This result suggests that PA is locally created in the vicinity of the division machinery. This local PA production may ensure robust spatial regulation of Drp1. These findings led to the hypothesis that PA inhibits Drp1 and the dissociation of Drp1 from MitoPLD activates mitochondrial division. In this proposed study, we will critically test this hypothesis and further develop and adjust it in an informed way. In Aim 1, we will determine how PA changes Drp1 activity using innovative biochemical, biophysical and cellular assays. We will also analyze how the mitochondrial lipid composition changes during division using lipidomics. In Aim 2, we will decipher how Drp1-MitoPLD interactions modulate the activity of both Drp1 and MitoPLD in mitochondrial division and how Drp1-MitoPLD interactions are regulated. We will also determine how MitoPLD controls the lipid composition in mitochondria. We expect that the outcomes of this proposed study will significantly advance the important biology of phospholipids and organelle dynamics and produce critical insights into human health and diseases.