Powering the Brain: Understanding how Astrocytes Contribute to Energy Maintenance

为大脑提供动力：了解星形胶质细胞如何有助于能量维持

• 批准号: RGPIN-2016-05463
• 负责人: Murai, Keith
• 金额: $ 2.77万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709721
• 关键词: Powering; Brain; Understanding; how; Astrocytes

The brain is the most energy expensive organ in the human body. To provide sufficient energy, neurons and glial cells harness oxidative phosphorylation in mitochondria to produce up to 90% of ATP required for cellular physiology. Remarkably, astrocytes, a highly specialized glial cell surrounding neurons, account for approximately 75% of ATP produced in the brain. The robust ATP production by astrocytes supports energy-consuming processing including extracellular ion maintenance, neurotransmitter homeostasis, and energy substrate transport from cerebrovasculature. Despite the known importance of energy production by astrocytes, fundamental aspects of this process in vivo remain unclear. Further investigation is need to resolve how these cells create, store, and distribute energy to maintain the structural and physiological integrity of cells in the brain. In this Discovery Research Program, we will study fundamental properties of astrocyte mitochondria using advanced in vivo gene delivery methods combined with cutting-edge imaging, molecular, and electrophysiology approaches. In Aim 1, we will use advanced methods to characterize mitochondria size, shape, and distribution in astrocytes and their cellular compartments (i.e. soma, distal processes, and endfeet) using cutting-edge light and electron microscopy approaches. Preliminary results indicate a complex organization of mitochondria in astrocytes in situ. Results from the proposed experiments will describe for the first time the 3-dimensional organization of mitochondria within individual astrocytes in the brain. In Aim 2, we will use live imaging approaches to monitor mitochondrial trafficking in astrocytes in situ and determine how neural activity and intracellular calcium dynamics in astrocytes relates to mitochondrial transport, fission/fusion events, and local recruitment to specific compartments. Preliminary results suggest that mitochondria are enriched at areas of high calcium dynamics in astrocytes. 2-photon imaging will be used to monitor these processes in the intact mouse brain. In Aim 3, we will identify mitochondrial trafficking components in astrocytes. We will initially focus on the trafficking protein kinesin binding 1 (TRAK1) and 2 (TRAK2) proteins in astrocytes that help target mitochondria in neurons. Preliminary results indicate specific mechanisms are used for mitochondrial targeting in astrocytes. We will determine how perturbation of mitochondrial trafficking in astrocytes impacts their anatomy and molecular features, as well as, the physiology of neighboring neurons. This grant will create a new level of understanding of astrocyte mechanisms that control energy delivery within the brain. Moreover, it will provide excellent conceptual and technical training for trainees at all levels interested in understanding fundamental aspects of brain function and homeostasis.

大脑是人体中能量消耗最大的器官。为了提供足够的能量，神经元和神经胶质细胞利用线粒体中的氧化磷酸化来产生高达90%的细胞生理所需的ATP。值得注意的是，星形胶质细胞，一种高度特化的神经胶质细胞周围的神经元，约占75%的ATP产生在大脑中。由星形胶质细胞产生的强大ATP支持能量消耗处理，包括细胞外离子维持、神经递质稳态和来自血管系统的能量底物运输。尽管已知星形胶质细胞产生能量的重要性，但体内这一过程的基本方面仍不清楚。需要进一步的研究来解决这些细胞如何创造，储存和分配能量，以维持大脑细胞的结构和生理完整性。在这个发现研究计划中，我们将使用先进的体内基因传递方法结合尖端的成像，分子和电生理学方法研究星形胶质细胞线粒体的基本特性。 在目标1中，我们将使用先进的方法来表征线粒体的大小，形状和分布在星形胶质细胞和他们的细胞室（即索马，远端过程，和endfeet）使用尖端的光和电子显微镜的方法。初步结果表明，一个复杂的组织线粒体在星形胶质细胞原位。从拟议的实验结果将描述第一次在大脑中的单个星形胶质细胞内的线粒体的三维组织。 在目标2中，我们将使用实时成像方法原位监测星形胶质细胞中的线粒体运输，并确定星形胶质细胞中的神经活性和细胞内钙动力学如何与线粒体运输，裂变/融合事件以及局部招募到特定隔室。初步结果表明，在星形胶质细胞中，线粒体富集在高钙动力学区域。2-光子成像将用于监测完整小鼠脑中的这些过程。 在目标3中，我们将鉴定星形胶质细胞中的线粒体运输组分。我们将首先集中在运输蛋白驱动蛋白结合1（TRAK 1）和2（TRAK 2）蛋白在星形胶质细胞，帮助靶向神经元线粒体。初步结果表明，特定的机制用于星形胶质细胞中的线粒体靶向。我们将确定星形胶质细胞中线粒体运输的扰动如何影响其解剖和分子特征，以及邻近神经元的生理学。 这项资助将创造一个新的水平的理解星形胶质细胞机制，控制大脑内的能量传递。此外，它将为有兴趣了解大脑功能和稳态的基本方面的各级学员提供出色的概念和技术培训。