Mechanisms of Mitochondrial Fission

描述(申请人提供)：线粒体是动态细胞器，其形态和功能受相反的分裂和融合的调节。利用这笔赠款提供的资金，我的实验室证明了一种名为DNM1的动力蛋白相关GTPase控制着萌芽酵母中的线粒体分裂。DNM1定义了一个保守的线粒体GTP酶家族，在细胞生理学和人类健康中具有重要但知之甚少的功能。 酵母DNM1的人类同源物被称为Drp1。在哺乳动物和细胞系中进行的研究表明，Drp1在维持线粒体功能、凋亡过程中线粒体的碎裂以及产生用于自噬的线粒体片段方面发挥着关键作用。根据这些发现，调节线粒体分裂的分子是抑制药物的潜在靶点，这些药物可以减少线粒体的碎裂和不必要的细胞死亡，包括中风后心肌细胞的凋亡性死亡或与各种神经疾病相关的神经细胞死亡。 这项提议的重点是发芽酵母的分裂机制，它是包括人类在内的所有真核生物中线粒体分裂机制的原型。这一领域已经成熟到主要问题集中在DNM1及其结合伙伴如何在适当的空间和时间控制下共同工作以引发裂变的阶段。为了超越这一阶段，关键是要更好地从机理和结构上了解DNM1裂变复合体的组件如何相互作用和组装，以及这些相互作用如何影响裂变活动。这里描述的研究旨在获得这种机制和结构信息。有了这些知识，我们将生成并测试调控DNM1组装和裂变复合体活动的特定模型。 与公众健康相关：拟议的研究将以酵母为模型系统，促进对调控线粒体分裂的分子的机制和结构的理解。这个核心线粒体分裂机制包括DNM1 GTP酶、MDv1/Caf4接头和Fis1膜锚定。这些结果将与人类发育和健康相关，因为这些蛋白质具有人类同源蛋白，包括人Drp1(酵母DNM1同源)及其膜受体人Fis1(酵母Fis1同源)。人类Drp1在维持线粒体功能、细胞凋亡过程中线粒体碎裂以及产生线粒体片段以进行自噬方面起着关键作用。最近，一名婴儿出生37天后死亡与Drp1基因突变有关。这项应用中的实验利用酵母中可用的复杂工具来探索裂变复合体组装和活性的机制。从这些研究中了解到的将使科学家和临床医生能够操纵这些分子的活动，以造福于人类健康。

DESCRIPTION (provided by applicant): Mitochondria are dynamic organelles whose morphology and function are regulated by opposing fission and fusion. Using funds provided by this grant, my laboratory demonstrated that a dynamin-related GTPase called Dnm1 controls mitochondrial fission in budding yeast. Dnm1 defines a conserved family of mitochondrial GTPases with important but poorly understood functions in cell physiology and human health. The human homolog of yeast Dnm1 is called Drp1. Studies performed in mammals and cell lines suggest that Drp1 plays critical roles in maintaining mitochondrial function, mitochondrial fragmentation during apoptosis, and generation of mitochondrial fragments for autophagy. Based on these findings, molecules that regulate mitochondrial fission are potential targets for inhibitory drugs that reduce mitochondrial fragmentation and unwanted cell death, including the apoptotic death of cardiac cells after stroke or the neuronal cell death associated with a variety of neuropathies. This proposal focuses on the fission machinery of budding yeast, which serves as the prototype for mitochondrial fission machineries in all eukaryotes, including humans. This field has matured to the stage where the major questions are focused on how Dnm1 and its binding partners work together to elicit fission with the proper spatial and temporal control. To progress beyond this stage, it is critical to obtain a better mechanistic and structural understanding of how components of the Dnm1 fission complex interact and assemble, and how these interactions affect fission activity. The studies described here are designed to obtain this mechanistic and structural information. With this knowledge in hand, we will generate and test specific models for the regulation of Dnm1 assembly and fission complex activity. PUBLIC HEALTH RELEVANCE: The proposed studies will advance mechanistic and structural understanding of the molecules that regulate mitochondrial fission using yeast as a model system. This core mitochondrial fission machinery includes the Dnm1 GTPase, Mdv1/Caf4 adaptors, and the Fis1 membrane anchor. The results will be relevant to human development and health, as these proteins have human homologs including human Drp1 (yeast Dnm1 homolog) and its membrane receptor human Fis1 (yeast Fis1 homolog). Human Drp1 plays critical roles in maintaining mitochondrial function, mitochondrial fragmentation during apoptosis, and generation of mitochondrial fragments for autophagy. A mutation in Drp1 was recently linked to the death of an infant 37 days after birth. Experiments in this application take advantage of the sophisticated tools available in yeast to probe the mechanism of fission complex assembly and activity. What is learned from these studies will allow scientists and clinicians to manipulate the activities of these molecules for the benefit of human health