Lipid-signaling pathways regulating mitochondrial morphology, energetics, and mov

描述(申请人提供)：这项建议侧重于一种假设，即线粒体表面的脂质信号通路有助于线粒体分裂的过程。我们已经发表的证据表明，脂磷脂酶1被脂磷脂酸(PA)通过蛋白质中心的PA结合结构域招募到线粒体表面，将PA转化为相关的信号脂二酰甘油(DAG)，从而促进线粒体的分裂。出乎意料的是，我们还发现Lipin 1在催化域中含有第二个神秘的线粒体靶向序列，该序列对未来裂变事件的位置表现出高度特异性的亚细胞定位。这导致了一个模型，即与PA结合引发构象变化，暴露第二个位点，该位点热衷于靶向线粒体小管上的分裂位点，并以与Drp1协同但也部分独立的方式健壮地触发分裂，Drp1是一种动态类蛋白质，被最广泛地研究为分裂的物理介质。本课题具有直接的临床意义。线粒体分裂的操作正在测试用于中风、心肌缺血和肺动脉高压的治疗应用；对分裂过程潜在机制的更多了解将有助于这些方法的发展。我们建议继续在脂蛋白1-裂变故事的背景下开发的感兴趣的领域，基于对DAG如何与裂变机械的其他组件合作触发裂变的探索。这些问题包括定义脂蛋白1在分裂部位与哪些蛋白质相互作用或通过DAG的产生进入分裂部位，这些蛋白质是否在分裂过程中发挥作用，它们的功能或分裂过程本身是否由脂蛋白1产生的DAG驱动。我们还将研究脂酶家族其他成员在分裂中的作用，探索脂类如何被招募到分裂部位，以及它与内质网(ER)和肌动蛋白细胞骨架重组的关系，这两个因素在分裂过程中发挥着重要作用。综上所述，这些研究将加深我们对裂变潜在机制的了解，并有助于开发与这一内在过程有关的针对疾病的治疗方法。

DESCRIPTION (provided by applicant): This proposal focuses on the hypothesis that a lipid signaling pathway on the surface of the mitochondria facilitates the process of mitochondrial fission. We have published evidence that the enzyme Lipin 1, which is recruited to the mitochondrial surface by the lipid phosphatidic acid (PA) via a PA-binding domain in the center of the protein, converts the PA to the related signaling lipid diacylglycerol (DAG), which then promotes mitochondrial fission. Unexpectedly, we also found that Lipin 1 harbors a second, cryptic mitochondrial targeting sequence in the catalytic domain that exhibits highly-specific subcellular localization to sites of future fission events. This led to a model that binding to PA triggers a conformational change to expose the second site which avidly targets fission sites on the mitochondrial tubule and robustly triggers fission in a collaborative but also partially independent manner with Drp1, the dynamic-like protein most widely studied as the physical mediator of fission. This topic has direct clinical significance. Manipulation of mitochondrial fission is being tested for therapeutic application in stroke, cardiac ischemia, and pulmonary hypertension; increased knowledge about mechanisms underlying the fission process will aid in development of these approaches. We propose to pursue areas of interest that have been developed in the context of the Lipin 1 - fission story based on exploration of how DAG triggers fission in collaboration with other components of the fission machinery. Such questions include defining the proteins Lipin 1 interacts with at fission sites or recruits to the fission sites throgh the production of DAG, whether these proteins have roles in the fission process, and whether their function or the fission process itself is driven by DAG production by Lipin 1. We will also examine roles for other members of the Lipin enzyme family in fission, explore how Lipin is recruited to fission sites, and its relationship to the endoplasmic reticulum (ER) and actin cytoskeletal reorganization, which play important roles in the fission process. Taken together, these studies will further our knowledge of the mechanisms underlying fission and be of utility in the development of therapies targeting diseases with connections to this intrinsic process.