Activity-dependent energy homeostasis at the presynaptic terminal

这项研究既与正常衰老有关，也与阿尔茨海默病等病理疾病有关，阿尔茨海默病的大脑功能 由于线粒体呼吸缺陷和细胞能量损失而受损。这个项目的长期目标是 是改善由于线粒体功能障碍引起的神经传递缺陷，作为阻止疾病的一种方式 进展到较晚的退化阶段，越来越容易受到年龄影响的人群的健康寿命增加- 相关的神经系统疾病。突触功能的生物能量学基础机制 为了治愈这些疾病，必须首先解决正常组织。我们在这个项目中的目标有两个。首先， 线粒体钙摄取在多大程度上促进了ATP的产生，以响应活动将被定义。 第二，在突触前终末使用补偿策略来延迟能量损失的程度将 确定线粒体功能受损的时间。这个项目的结果将提供明确的机制 深入了解突触线粒体的钙缓冲和ATP产生作用，这是至关重要的第一步 目前尚不清楚。 PI已经开发了几种新的方法，使我们能够剖析用于 结合使用电生理学、钙离子成像和 ATP成像。与小型常规突触不同的是，啮齿动物中的巨型“花盏状”兴奋性突触 听觉脑干允许从突触前终末直接进行全细胞记录。这项实验 可访问性允许操纵突触前[Ca~(2+)]和[ATP]，从而有可能解剖 突触线粒体相互依赖的钙缓冲和能量支持作用。在第一个具体目标中， 线粒体钙单转运体(MCU)促进线粒体呼吸和ATP动态平衡的程度 随后的突触活动将被确定。第二个具体目标将剖析 突触传递和突触前短期线粒体钙摄取与促进呼吸的比较 可塑性。也就是说，MCU对突触的钙缓冲和ATP动态平衡更重要吗？具体而言 目标三：糖酵解和线粒体呼吸之间代谢转换的结果 在正常突触中，以及在MCU功能急性或慢性的情况下，将检查传递的 受伤了。 本项目将提供对新陈代谢策略范围的详细了解 突触在生理和病理环境中支持突触传递。这一知识将确定 可利用的恢复能量缺乏突触功能的可行干预途径 在治疗上缓解疾病相关的突触功能障碍。

This work is relevant to both normal aging and pathologies like Alzheimer’s disease, where brain function is impaired due to defective mitochondrial respiration and loss of cellular energy. The long-term goal of this project is to ameliorate neurotransmission defects due to mitochondrial dysfunction, as a way to stop disease progression to later degenerative stages, increasing healthspan in populations increasingly subject to age- related neurological diseases. Fundamental mechanisms underlying the bioenergetics of synaptic function in normal tissue must be resolved first, to cure these diseases. Our goals in this project are two-fold. First, the extent to which mitochondrial Ca2+ uptake facilitates ATP production in response to activity will be defined. Second, the extent that compensatory strategies are utilized at the presynaptic terminal to delay energy loss will be determined when mitochondrial function is impaired. Results from this project will provide clear mechanistic insight into the Ca2+-buffering and ATP-producing roles of synaptic mitochondria, an essential first step that is currently unclear. The PI has developed several novel approaches that allow us to dissect the bioenergetic strategies used to support transmission at the mouse calyx of Held, using a combination of electrophysiology, Ca2+ imaging, and ATP imaging. In contrast to small conventional synapses, giant ‘calyx-like’ excitatory synapses in the rodent auditory brainstem allow direct whole-cell recordings from the presynaptic terminal. This experimental accessibility permits manipulation of presynaptic [Ca2+] and [ATP], making it possible to dissect the interdependent Ca2+-buffering and energy-supporting roles of synaptic mitochondria. In the first Specific Aim, the extent that the mitochondrial calcium uniporter (MCU) facilitates mitochondrial respiration and ATP homeostasis following synaptic activity will be determined. The second Specific Aim will dissect the importance of mitochondrial Ca2+ uptake versus facilitated respiration on synaptic transmission and presynaptic short-term plasticity. Namely, is the MCU more important for Ca2+ buffering or ATP homeostasis at the synapse? In Specific Aim three, the consequence of metabolic switching between glycolysis and mitochondrial respiration in support of transmission will be examined in normal synapses, and in cases where MCU function is acutely or chronically impaired. This project will provide a detailed understanding of the range of metabolic strategies that are employed by synapses to support synaptic transmission in physiological and pathological settings. This knowledge will identify viable routes of intervention for restoring function to energy-deficient synapses that can be leveraged therapeutically to alleviate disease-related synaptic dysfunction.