The role of glial cells in the development and function of retinal circuits

描述（由申请人提供）：越来越多的证据表明，神经元和神经胶质细胞参与双向信号传导，影响神经回路的功能和发育。胶质细胞可以通过控制突触外空间神经递质的数量来影响神经元的兴奋性，并直接调节突触传递。此外，神经胶质细胞是控制神经元代谢的神经血管相互作用的中央调节器。为了更好地理解神经胶质的功能，必须阐明神经元和神经胶质之间的密切相互作用是如何在发育过程中建立的，以及这对神经回路稳定性的影响。该建议描述了一种方法来阐明神经胶质细胞信号在小鼠视网膜回路的发展中的作用。拟议的研究将为一项长期研究计划提供基础，该计划致力于探索神经元、胶质细胞和血管之间的精确信号传导是如何建立和维持的。米Ller神经胶质细胞是视网膜中最后增殖的细胞类型，并且必须在称为视网膜波的自发相关活动期间整合到现有的未成熟回路中。在睁眼前不久，视网膜波由谷氨酸能信号传导介导，并被认为是通过谷氨酸溢出传播到突触外空间。米勒细胞的形态和功能在脑电波期间成熟，并且可以在波停止和视觉开始时稳定视网膜回路。两种形式的神经胶质细胞信号在这个建议进行了探讨。在第一个目标中，我们将 确定胶质细胞转运功能的成熟如何影响神经元回路的发育。在第二个目标中，我们将研究自发和诱发的神经元活动如何影响神经胶质细胞钙信号。在目的1中，我们将使用光学和电生理学方法来描述M？ller细胞转运蛋白功能的成熟。谷氨酸的水平可以用谷氨酸光学传感器直接观察到，当谷氨酸结合时荧光增加。我将使用这些传感器来监测从视网膜波到视觉的过渡期间突触外谷氨酸盐，并确定谷氨酸盐溢出是否到达M？ller细胞。米Ller转运蛋白将被阻断，神经元群的双光子钙成像将用于评估对视网膜回路的影响。在目标2中，我们将使用转基因小鼠在M？ller细胞中表达钙指示剂GCaMP 3，以研究神经活动是否在整个视网膜发育过程中驱动M？ller钙瞬变。了解神经胶质细胞如何改变神经元的功能，因为他们融入成熟的电路将导致神经元-神经胶质细胞信号的细胞和分子机制的基本见解。神经元-胶质细胞相互作用的维持对神经系统的健康至关重要，特别是胶质细胞转运蛋白功能已被临床证明 意义

DESCRIPTION (provided by applicant): Mounting evidence suggests that neurons and glia engage in bi-directional signaling that affects the function and development of neural circuits. Glia can influence the excitability of neurons, by controlling the amount of neurotransmitters in the extrasynaptic space, and can directly modulate synaptic transmission. In addition, glia are the central regulators of the neurovascular interactions that control neuronal metabolism. To better understand glial function, it is essential to unravel how the close interaction between neurons and glia is established during development and the effect this has on the stabilization of neural circuits. This proposal describes an approach to elucidate the role of neuron-glia signaling in the development of murine retinal circuits. The proposed investigations will provide the basis for a long-term research program dedicated to exploring how the precise signaling between neurons, glia, and blood vessels is established and maintained. M¿ller glia are the last cell type to proliferate in the retina, and must integrate into an existing immature circuit duringa period of spontaneous correlated activity called retinal waves. Shortly before eye opening, retinal waves are mediated by glutamatergic signaling and are thought to propagate by glutamate spillover into the extrasynaptic space. M¿ller cells mature in morphology and function during glutamatergic waves, and may stabilize retinal circuits when waves cease and vision begins. Two forms of neuron-glia signaling are explored in this proposal. In the first aim, we will determine how the maturation of glial cell transporter function affects the development of neuronal circuits. In the second aim, we will investigate how spontaneous and evoked neuronal activity influences glial calcium signaling. In aim 1 we will use optical and electrophysiological methods to describe the maturation of M¿ller cell transporter function. Levels of glutamate can be directly observed with glutamate optical sensors that increase in fluorescence when glutamate binds. I will use these sensors to monitor extrasynaptic glutamate during the transition from retinal waves to vision, and to ascertain whether or not glutamate spillover reaches M¿ller cells. M¿ller transporters will be blocked pharmacologically and two-photon calcium imaging of neuronal populations will be used to assess the effect on retinal circuits. In aim 2 we will use transgenic mice expressing the calcium indicator GCaMP3 in M¿ller cells to investigate whether neural activity drives M¿ller calcium transients throughout retinal development. An understanding of how glial cells change neuronal function as they integrate into maturing circuits will lead to fundamental insights about the cellular and molecular mechanisms of neuron-glia signaling. The maintenance of neuron-glia interactions is vital for the health of the nervous system, and in particular, the glial transporter function has proven clinical significance.