Activity-dependent energy homeostasis at the presynaptic terminal

这项工作与正常衰老和阿尔茨海默病等病理学有关，阿尔茨海默病是大脑功能受损的疾病。 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， 发展到后期退行性阶段，增加人口的健康寿命越来越受年龄的影响， 相关的神经系统疾病。神经元突触功能生物能量学的基本机制 要想治愈这些疾病，必须首先解决正常组织。我们在这个项目中的目标是双重的。一是 将确定线粒体Ca2+摄取促进响应于活性的ATP产生的程度。 第二，在突触前末梢利用补偿策略来延迟能量损失的程度将 当线粒体功能受损时确定。该项目的结果将提供明确的机制 深入了解突触线粒体的Ca2+缓冲和ATP产生作用，这是重要的第一步， 目前不清楚。 PI已经开发了几种新的方法，使我们能够剖析生物能量策略， 支持传输在小鼠肾盏的Held，使用电生理学，Ca2+成像的组合， ATP成像。与传统的小突触相反，啮齿动物中的巨大“萼状”兴奋性突触 听觉脑干允许来自突触前末梢的直接全细胞记录。该实验 可接近性允许操纵突触前[Ca2+]和[ATP]，使得有可能解剖 突触线粒体的相互依赖的Ca2+缓冲和能量支持作用。在第一个具体目标中， 线粒体钙单向转运体（MCU）促进线粒体呼吸和ATP稳态的程度 将确定随后的突触活动。第二个具体目标将剖析的重要性， 线粒体Ca2+摄取与易化呼吸对突触传递和突触前短时程的影响 可塑性也就是说，MCU对突触处的Ca2+缓冲或ATP稳态更重要吗？在特定 目的三，糖酵解和线粒体呼吸之间的代谢转换的结果， 将在正常突触中检查，以及MCU功能急性或慢性受损的情况下， 受损 该项目将提供一个详细的了解代谢策略的范围，采用 突触以支持生理和病理环境中的突触传递。这些知识将识别 恢复能量缺乏突触功能的可行干预途径， 在治疗上减轻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.