Formation and Elimination of Synapses

描述（由申请人提供）：本研究的长期目标是阐明突触功能、形成、重塑和维持的基本细胞和分子机制。本研究旨在通过验证以下关于蛙神经肌肉连接处（NMJ）突触-胶质相互作用的假设，揭示突触周围雪旺细胞（PSC）这一突触相关胶质细胞的新作用：(1)验证PSC是成年NMJ维持和发芽所必需的假设。一种利用补体介导的裂解在体内选择性消融PSC的新技术将被应用于研究PSC消融对突触结构（突触前神经末梢和突触后乙酰胆碱受体）维持和神经末梢发芽的影响。(2)验证PSCs调节成年NMJs突触传递的假说。PSC消融对突触功能（终板电位、成对脉冲促进和突触抑制）的短期和长期影响将通过细胞内记录进行检查。(3)验证PSCs在体内促进NMJs形成和功能的假说。体内PSC消融对突触生长和递质释放的影响将在蝌蚪和年轻青蛙肌肉中进行研究。(4)验证雪旺细胞源性因子在体外促进NMJs形成和功能发育的假说。雪旺细胞条件培养基对突触生理学和形态学的影响将在神经-肌肉培养中进行检验。拟议的研究将使用体内和体外方法来测试一个新兴的概念，即神经胶质细胞告诉神经元建立更大、更强、更稳定的突触。对突触-神经胶质相互作用机制的深入了解将有助于更好地理解神经肌肉疾病和创伤后轴突再生，以及神经系统的发育和可塑性。

DESCRIPTION (provided by applicant): The long-term objectives of this research are to elucidate basic cellular and molecular mechanisms of synaptic function, formation, remodeling and maintenance. The present proposal aims to reveal novel roles of the perisynaptic Schwann cell (PSC), a synapse-associated glial cell, by testing the following hypotheses regarding synapse-glial interactions at the frog neuromuscular junction (NMJ):(1) To test the hypothesis that PSCs are required for the maintenance and sprouting of adult NMJs. A novel technique using complement-mediated lysis to selectively ablate PSCs in vivo will be applied to study the effect of PSC ablation on maintenance of synaptic structure (presynaptic nerve terminals and postsynaptic acetylcholine receptors), and on nerve terminal sprouting. (2) To test the hypothesis that PSCs modulate synaptic transmission at adult NMJs. Both short- and long-term effects of PSC ablation on synaptic function (endplate potentials, paired-pulse facilitation and synaptic depression) will be examined with intracellular recording. (3) To test the hypothesis that PSCs promote the formation and function of developing NMJs in vivo. The effects of in vivo PSC ablation on synaptic growth and transmitter release will be examined in tadpole and young frog muscles. (4) To test the hypothesis that Schwann cell-derived factors promote the formation and function of developing NMJs in vitro. The effects of Schwann cell-conditioned medium on synaptic physiology and morphology will be examined in nerve-muscle cultures.The proposed research will use both in vivo and in vitro approaches to test an emerging concept that glial cells tell neurons to build larger, stronger and more stable synapses. The insights into the mechanism of synapse-glial interactions will contribute to a better understanding of neuromuscular diseases and axonal regeneration after trauma, as well as development and plasticity of the nervous system.