Ephrin-A3 in Neuron-Glia Communication

神经胶质细胞在神经元的发育和功能中起着关键作用。然而，胶质细胞交换的信号 人们对细胞和神经元知之甚少。越来越多的证据支持伊夫林和伊夫林 受体在神经胶质细胞和神经元轴突之间的相互作用中起着重要作用 中枢神经系统和外周神经系统不同部位的树突。我们最近发现了一种新的形式 涉及星形胶质细胞表面表达的ePhin-A3配体的神经元-神经胶质细胞通讯 海马体和EphA4受体酪氨酸激酶在树突棘上表达。树突棘 是神经元树突上的小突起，使突触与轴突终末接触。通常， 成熟的脊椎有一个较大的头部，通过一个狭窄的颈部与树突相连。的变化 海马体中树突棘的形状、大小和数量可能有助于学习和存储长期记忆 回忆。我们的证据表明，ePhin-A3和EphA4之间的相互作用介导了一种形式的 星形胶质细胞和神经元之间的排斥通讯，抵消了促进 脊椎增大，防止脊椎扭曲和解体。这可能代表一种 学习和记忆形成过程中脊柱重塑的调控机制。重要的是 交流可能是双向的，ePhin-A3也会启动信号，影响 星形胶质细胞与EphA4阳性树突接触。该项目的目标是评估 胶质细胞肾上腺素A3在大鼠树突棘发育、重塑和突触传递中的调节作用 海马神经元。此外，我们还将研究由ePhin-A3和Ephin-A3介导的信号通路。 它们在星形胶质细胞生理学中的作用。新近获得的ephin-A3基因敲除小鼠将成为 实现这些目标。这项拟议的研究将提供有关ePhin-A3基因突变的信息 基因导致以树突棘异常为特征的神经系统疾病，包括 精神发育迟缓、自闭症、癫痫和精神分裂症，以及ephin-A3基因敲除小鼠是否可能 代表了一种有用的神经疾病模型。操控神经胶质细胞中的肾上腺素功能的策略可能 帮助治疗涉及海马神经元-神经胶质细胞异常相互作用的神经疾病 神经系统的其他区域。

Glial cells play a key role in neuronal development and function. However, the signals exchanged by glial cells and neurons are poorly understood. Increasing evidence supports the notion that ephrins and Eph receptors play an important role in the interactions between glial cells and neuronal axons as well as dendrites in different parts of the central and peripheral nervous system. We recently discovered a new form of neuron-glia communication that involves the ephrin-A3 ligand expressed on the surface of astrocytes in the hippocampus and the EphA4 receptor tyrosine kinase expressed on dendritic spines. Dendritic spines are small protrusions on neuronal dendrites that make synaptic contact with axonal terminals. Typically, mature spines have an enlarged head connected to the dendrite through a narrow neck. Changes in the shape, size and number of dendritic spines in the hippocampus likely contribute to learning and storing longterm memories. Our evidence suggests that the interplay between ephrin-A3 and EphA4 mediates a form of repulsive communication between astrocytes and neurons that counteracts signals promoting the enlargement of spines and prevents distortion and disorganization of the spines. This may represent a mechanism regulating spine remodeling during learning and memory formation. Importantly the communication likely is bidirectional, with ephrin-A3 also initiating signals that affect the properties of astrocytes coming in contact with EphA4-positive dendrites. The goal of this project is to evaluate the role of glial ephrin-A3 in the regulation of dendritic spine development and remodeling and synaptic transmission in hippocampal neurons. Furthermore, we will investigate the signaling pathways mediated by ephrin-A3 and their role in astrocyte physiology. Recently obtained ephrin-A3 knockout mice will be important tools to achieve these goals. The proposed research will provide information on whether mutations in the ephrin-A3 gene contribute to neurological diseases characterized by abnormalities in dendritic spines¿including mental retardation, autism, epilepsy, and schizophrenia¿and whether the ephrin-A3 knockout mouse may represent a useful neurological disease model. Strategies to manipulate ephrin function in glial cells could help treatment of neurological disorders involving aberrant neuron-glia interactions in the hippocampus and other regions of the nervous system.