Synchronized Formation and Remodeling of Postsynaptic Densities: Long-Term Visualization of Hippocampal Neurons Expressing Postsynaptic Density Proteins Tagged with Green Fluorescent Protein
Synchronized Formation and Remodeling of Postsynaptic Densities: Long-Term Visualization of Hippocampal Neurons Expressing Postsynaptic Density Proteins Tagged with Green Fluorescent Protein
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DOI：
10.1523/jneurosci.23-06-02170.2003
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发表时间：
2003-03
期刊：
影响因子：
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通讯作者：
T. Ebihara;I. Kawabata;S. Usui;K. Sobue;S. Okabe
中科院分区：
文献类型：
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作者：
T. Ebihara;I. Kawabata;S. Usui;K. Sobue;S. Okabe
为了探索突触后密度（PSD）的形成和重塑的机制，我们使用了分离自表达绿色荧光蛋白（GFP）标记的PSD蛋白PSD-Zip 45（Homer 1c）和PSD-95的转基因胚胎的海马神经元的解离培养物。GFP标记的PSD分子的表达是稳定的，并且PSD的重塑过程可以跟踪>1周。GFP-PSD-Zip 45的较高表达水平使我们能够定量分析发育期间PSD-Zip 45簇的量。在培养11至17天之间对相同细胞群的重复成像显示，平均PSD-Zip 45簇密度从0.32/μm增加到0.73/μm。新生成的树突迅速获得GFP-PSD-Zip 45簇，并且它们的密度在几天内达到亲本树突的水平。GFP-PSD-Zip 45簇密度的时间曲线显示出多种模式。一些树突表现出单调增加的集群，而其他人表现出复杂的模式，包括短递减阶段。PSD-95-GFP簇的长期重塑的分析证实，递减阶段不是PSD-Zip 45簇所特有的。神经元之间簇密度的时间分布的比较表明单个细胞内GFP-PSD-Zip 45和PSD-95簇的同步。此外，cAMP依赖性蛋白激酶的激活抑制了簇重塑的递减阶段。这些观察结果表明，存在的信号传导机制，可以诱导同步添加或消除PSD蛋白在整个树突状分支的一个单一的神经元。
To explore mechanisms governing the formation and remodeling of postsynaptic density (PSD), we used dissociated cultures of hippocampal neurons isolated from transgenic embryos expressing green fluorescent protein (GFP)-tagged PSD proteins PSD-Zip45 (Homer 1c) and PSD-95. Expression of GFP-tagged PSD molecules was stable, and the remodeling process of PSDs could be followed for >1 week. A higher expression level of GFP-PSD-Zip45 enabled us to quantitatively analyze the amount of PSD-Zip45 clusters during development. Repetitive imaging of the same cell populations between 11 and 17 d in culture revealed an increase of the average PSD-Zip45 cluster density from 0.32 to 0.73/μm. Newly generated dendrites rapidly acquired GFP-PSD-Zip45 clusters, and their density reached the level of parental dendrites within a few days. Temporal profiles of GFP-PSD-Zip45 cluster density showed a variety of patterns. Some dendrites showed a monotonous increase of clusters, whereas others showed complex patterns, including short decremental stages. Analysis of long-term remodeling of PSD-95-GFP clusters confirmed that the decremental stages were not specific to the PSD-Zip45 clusters. Comparison of the temporal profiles of the cluster density among neurons indicated synchronization of both GFP-PSD-Zip45 and PSD-95 clustering within individual cells. Furthermore, activation of cAMP-dependent protein kinase suppressed the decremental stages of cluster remodeling. These observations suggest the presence of signaling mechanisms that can induce synchronized addition or elimination of PSD proteins throughout dendritic arborization of a single neuron.