Determining the role of mitochondrial trafficking in activity-dependent structural synaptic plasticity

项目摘要/摘要 我们的大脑通过神经元之间错综复杂的电子通讯来执行复杂的认知任务。 发生这种交流的专门站点是突触，它能够以各种形式 可塑性，使神经元之间的通信能够不断地和自适应地细化。这个 在突触传递的神经元活动量通常决定了修饰的类型，并且 提高神经元之间的交流水平通过自适应的 增加连接数量。这一过程统称为活动依赖突触 可塑性，被认为是学习和记忆的细胞基础。 这个项目的长期目标是更好地理解依赖活性的基本细胞生物学根源 突触可塑性。特别是，我对了解细胞内的功能作用感兴趣 线粒体运输在支持突触生长中的作用，以适应神经元激活的增加。这就做 利用果蝇幼虫或果蝇幼虫作为实验模型，进行这一项目 由于有强大的遗传工具，所以选择了这一系统。就像我们脊髓中的运动神经元一样， 幼虫体壁的肌肉由运动神经元支配，运动神经元负责发送 发出何时移动的信号。这些运动神经元在肌肉上形成突触，这被称为 神经肌肉接头(NMJ)突触。NMJ突触的突触前终末将经历活动- 依赖于运动神经元活动增加的可塑性，依赖于幼虫活动的增加。我可以的 利用研发的技术，直接通过幼虫的角质层(皮肤)对这种突触进行显微成像 包括它不断变化的形状和细胞内的动力学(如线粒体的变化)， 当神经元活性增加时，与生长同步发生。 我的中心假设是，神经元活动诱导急性突触生长的形成，即 最终通过线粒体的贩运稳定下来，这有助于它的长期发展 成熟后成为成熟的突触连接。使用我描述的工具，我将检验这一假设 具体有两个目标：(1)我将使用一种基因突变的幼虫，在这种突变幼虫中，线粒体运输到NMJ 看依赖活动的增长是否有任何方面是成功的，因此准确地指出 线粒体贩运在这一过程中的作用。(2)我将寻求对分子介体进行功能性表征 负责促进活性依赖的突触生长，并确定其驱动力是否 促进突触生长的能力在于它对线粒体运输的调节。从以下方面获得的洞察 这项工作将揭示突触可塑性和线粒体运输的细胞生物学方面的新知识。 神经元，这两个过程在功能失调时通常会导致神经退行性疾病。

Project Summary/Abstract Our brains carry out complex cognitive tasks via the intricate electrical communication between neurons. The specialized site where this communication occurs is the synapse, and it is capable of various forms of plasticity that enable the constant and adaptive refinement of the communication between neurons. The amount of neuronal activity that is transmitted at the synapse typically dictates the type of modification, and raising the level of communication between neurons strengthens their synaptic connection through an adaptive increase in the number of connections. This process is collectively known as activity-dependent synaptic plasticity, and is thought to be the cellular foundation for learning and memory. The long term goal of this project is to better understand the basic cell biological roots of activity-dependent synaptic plasticity. In particular, I am interested in understanding the functional role of intracellular mitochondrial trafficking in supporting the growth of synapses adapting to increased neuronal activation. I will carry out this project using Drosophila Melanogaster larvae, or fruit fly maggots, as an experimental model system that was chosen due to the powerful genetic tools available. Like motor neurons in our spinal cord, the muscles in the body wall of the larvae are innervated by motoneurons that are responsible for sending the signal when to move. These motoneurons form a synapse onto the muscle, which is known as the neuromuscular junction (NMJ) synapse. The presynaptic terminal of the NMJ synapse will undergo activity- dependent plasticity upon increased activity of the motoneurons, from increased movement of the larvae. I can microscopically image this synapse directly through the cuticle (skin) of the larvae using technology developed in my lab; including its changing shape and intracellular dynamics (such as changes in mitochondria) that occur simultaneously with the growth when neuronal activity is increased. My central hypothesis is that neuronal activity induces the formation of acute synaptic growth that is eventually stabilized by the trafficking of mitochondria into this nascent growth, which facilitates its long-term maturation to becoming a mature synaptic connection. Using the tools I described, I will test this hypothesis with two specific aims: (1) I will use a genetic mutant larvae in which the trafficking of mitochondria to the NMJ is dysfunctional to see if any aspects of activity-dependent growth are successful, hence pinpointing a precise role for mitochondrial trafficking in the process. (2) I will seek to functionally characterize a molecular mediator responsible for promoting activity-dependent synaptic growth, and determine whether the driving force for its ability to promote the growth of synapses is in its regulation of mitochondrial trafficking. The insight gained from this work will uncover new knowledge on the cell biology of synaptic plasticity and mitochondrial trafficking in neurons, two processes that commonly result in neurodegenerative diseases when dysfunctional.