Neuron-glia interactions in Drosophila visual neuropiles

果蝇视觉神经桩中神经元-胶质细胞的相互作用

• 批准号: 9767199
• 负责人: HONG-SHENG LI
• 金额: $ 41.88万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-30 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9767199
• 关键词: Animals; Area; Astrocytes; Axon; Bathing; Biological; Biological Assay; Brain; Cations; Cell physiology; Cells; Communication; Defect; Dendrites; Down-Regulation; Drosophila genus; Electrophysiology (science); Electroretinography; Epithelial; Extracellular Space; Gated Ion Channel; Genetic; Genetic Models; Glutamate Transporter; Glutamates; Goals; Histamine Release; Histologic; Impairment; Interneurons; Ion Channel Gating; Ions; Knowledge; Light; Locomotion; Maintenance; Mammals; Mediating; Membrane; Membrane Potentials; Mental disorders; Modeling; Molecular; Motion; Muller' s cell; Neurobiology; Neuroglia; Neurons; Neuropil; Neurotransmitter Receptor; Neurotransmitters; Pathologic; Phenocopy; Photoreceptors; Phototransduction; Physiological; Process; Reporter; Research; Retina; Retinal Diseases; Role; Signal Transduction; Signaling Molecule; Slice; Structure; Supporting Cell; Synapses; Synaptic Transmission; Testing; Vision; Visual; Visual system structure; Weight; base; fly; genetic manipulation; glutamate-gated chloride channel; imaging approach; in vitro testing; in vivo; in vivo imaging; mutant; neuronal circuitry; neurotransmission; novel; postsynaptic neurons; response; transmission process; voltage

ABSTRACT The long-term goal of the proposed research is to reveal how electrically non-excitable glial cells modulate synaptic transmission in response to neuronal inputs using fly visual system as a model. Previous studies on vision mostly have been focused on the visual transduction cascades and the neuronal circuits, whereas our knowledge about the role of glial cells in vision is very limited. Neurobiological research in the last decade has found that, In addition to their supportive role in neuron survival and function, the central neuropil glia astrocytes can respond to various neurotransmitters, and likely modulate neuronal synaptic transmissions. Neurotransmitter receptors are also detected in visual glia including Müller cells. However, it remains to be elucidated how glia modulate synaptic transmission in visual system, and how this glial function is controlled conversely by neurons. To study this function of perisynaptic glia, we plan to use the Drosophila visual system as a novel model, which allows genetic manipulation of signaling molecules specifically in glia or neuron, as well as subsequent observation of neuronal activities via reporters in live animals with intact glial networks. In the first visual neuropil region (lamina) of fly, photoreceptor axons release histamine upon light stimulation to hyperpolarize projective large monopolar cells (LMC). All neuronal processes are wrapped laterally by three epithelial glia cells (EG) in each laminar cartridge. We have previous found that EG concentrate a glutamate-gated chloride channel GluCl in special membrane processes abutting terminals of T1 interneuron. Our preliminary study showed that loss of GluCl diminished the Ca2+ response of LMC to light change, and impaired fly locomotion vision in dim conditions. Both dark-vision and electroretinogram defects of the GluCl mutant were phenocopied by downregulation of a glutamate transporter EAAT1 in T1, suggesting the involvement of T1 neuron and EAAT1 in the stimulation of GluCl. Finally, a cation channel NA in T1 appeared to function upstream of GluCl as well. Based on these observations, we propose to test a voltage-dependent, non-vesicular mechanism of neuron-glia communication, in which T1 neuron releases glutamate through EAAT1 to open a GluCl-gated Cl- pool in EG, thereby facilitating the inhibition of LMC by photoreceptors. This model may represent a general mechanism for interneuron to modulate synaptic weight through glia in both flies and mammals, and may occur in central brain as well. Using a combination of molecular and cell biological, genetic, histological, electrophysiological and in vivo imaging approaches, we will specifically demonstrate that 1) a GluCl-gated glial Cl- pool is essential for the inhibitory visual transmission; 2) T1 neuron releases glutamate through EAAT1 to open glial GluCl channel; and 3) depolarization of T1 is required for EAAT1 to release glutamate.

摘要 这项研究的长期目标是揭示电非兴奋性神经胶质细胞如何调节 以果蝇视觉系统为模型，研究神经元输入对突触传递的影响。以前的研究 关于视觉的研究主要集中在视觉传导级联和神经回路上，而 我们对神经胶质细胞在视觉中的作用的了解非常有限。神经生物学研究在过去的 十年来已经发现，除了它们在神经元存活和功能中的支持作用外， 神经胶质星形胶质细胞可以对各种神经递质作出反应，并可能调节神经元突触 传动.神经递质受体也在视觉神经胶质细胞（包括Müller细胞）中检测到。然而，在这方面， 神经胶质细胞如何调节视觉系统中的突触传递， 相反，神经元控制功能。 为了研究突触周围神经胶质细胞的这种功能，我们计划使用果蝇视觉系统作为一种新的模型， 它允许遗传操纵信号分子，特别是在神经胶质细胞或神经元，以及 随后在具有完整神经胶质网络的活体动物中通过报告子观察神经元活动。在 在果蝇的第一视觉神经元区域（层），光感受器轴突在光刺激时释放组胺， 高血压投射性大单极细胞（LMC）。所有的神经突起都被三个 上皮神经胶质细胞（EG）。我们以前发现EG浓缩物 谷氨酸门控氯离子通道GluCl在特殊的膜过程邻接终端的T1 中间神经元我们的初步研究表明，GluCl的缺失降低了LMC对光的Ca ~（2+）反应 改变，并在昏暗条件下损害苍蝇运动视觉。暗视觉和视网膜电图 GluCl突变体的缺陷通过T1中谷氨酸转运体EAAT 1的下调而表型复制， 提示T1神经元和EAAT 1参与了GluCl的刺激。最后，阳离子通道 T1中的NA似乎也在GluCl的上游起作用。根据这些观察，我们建议测试 神经元-胶质细胞通讯的电压依赖性非囊泡机制，其中T1神经元释放 谷氨酸通过EAAT 1打开EG中的GluCl门控Cl池，从而促进LMC的抑制， 光感受器该模型可能代表了中间神经元调节突触的一般机制。 在果蝇和哺乳动物中，通过神经胶质加重体重，也可能发生在中枢脑中。使用组合 分子和细胞生物学、遗传学、组织学、电生理学和体内成像方法， 我们将具体证明：1）GluCl门控的胶质细胞Cl-池对于抑制性视觉功能是必不可少的， 2）T1神经元通过EAAT 1释放谷氨酸，打开胶质细胞GluCl通道; 3） T1的去极化是EAAT 1释放谷氨酸所必需的。