Dynamics of Synaptic Proteins in C.elegans

对哺乳动物神经元中突触蛋白和脊椎形态的长期观察表明，在体外和体内，部分突触群体持续更新。此外，最近对哺乳动物突触蛋白的分析表明，突触中的蛋白质组成迅速变化，并受到神经元活动的调节。突触结构和分子组成的持续变化的意义应该在一个系统中进行评估，在这个系统中，电路特性的变化和由此导致的行为变化之间的直接相关分析是可能的。在线虫中，所有302个神经元的电路都有完整的描述，并且已经确定了控制感觉-运动协调的特定神经元和基因集。因此，对参与感觉-运动协调的神经元之间正常突触功能所必需的突触蛋白的长期可视化将是测试syna…行为意义的理想模型系统。为此，我们重点研究了线虫多模式感觉神经元ASH和运动控制回路(命令神经元)的中间神经元之间的谷氨酸能突触。ASH指令神经元突触的谷氨酸能传递对鼻子触摸的反应是必不可少的。为了可视化突触后成分，我们利用了离子型谷氨酸受体GLR-1和绿色荧光蛋白(GLR-1：：GFP)之间的融合蛋白，并通过真实的GLR-1启动子或支持GLR-1在中间神经元亚群中表达的核磁共振-1启动子表达了该报告基因。图像由双光子激光扫描显微镜获得。在GLR-1启动子控制下表达GLR-1-GFP的转基因虫子在神经环和腹神经索均有荧光团。腹神经索中GLR-1：：GFP簇的短期和长期重塑的时间推移成像显示了短期结构稳定性和发育依赖性重塑。在核磁共振-1启动子控制下表达GLR-1：：GFP的转基因蠕虫中，神经环内可见较少数量的荧光团。长波长荧光探针对ASH神经元的解剖定位和双重标记表明，一些GLR-1：：GFP簇对应于ASH和命令神经元之间的突触连接。较少

Long-term visualization of synaptic proteins and spine morphology in mammalian neurons revealed continual turnover of a fraction of synapse population in vitro and in vivo. Furthermore, recent analysis of mammalian synaptic proteins showed rapid alterations of protein compositions in synapses and their regulation by neuronal activity. Significance of continual alterations of synaptic structure and molecular compositions should be evaluated in a system where direct correlational analyses between changes of circuit properties and resulting behavioral alterations are possible. In C.elegans, full descriptions of the circuitry of all 302 neurons are available and specific sets of neurons and genes that control the sensory-motor coordination have been identified. Therefore, long-term visualization of synaptic proteins essential in the proper synaptic functions between neurons involved in the sensory-motor coordination would be an ideal model system to test the behavioral significance of syna … More pse remodeling.To this end, we focused on the glutamatergic synapses between polymodal sensory neuron ASH and interneurons of the locomotory control circuit (command neurons) of C.elegans. The glutamatergic transmission at ASH-command neuron synapses is essential for response to nose-touch. To visualize postsynaptic component, we utilized a fusion protein between ionotropic glutamate receptor GLR-1 and green fluorescent protein (GLR-1::GFP) and expressed this reporter gene either by an authentic glr-1 promoter or nmr-1 promoter that support expression of GLR-1 in a subset of interneurons. Images were obtained by a two-photon laser scanning microscope. Transgenic worms expressing GLR-1-GFP under the control of glr-1 promoter showed fluorescent clusters in both the nerve ring and the ventral nerve cord. Time-lapse imaging of short- and long-term remodeling of GLR-1::GFP clusters in the ventral nerve cord revealed both short-term structural stability and development-dependent remodeling. In transgenic worms expressing GLR-1::GFP under the control of nmr-1 promoter, a smaller number of fluorescent clusters were visualized within the nerve ring. Anatomical location and double labeling of ASH neurons with longer-wavelength fluorescent probes suggested that some of the GLR-1::GFP clusters corresponded to the synaptic junctions between ASH and command neurons. Less