Bresler T, Ramati Y, Zamorano P L, Zhai R, Garner C C, Ziv N E
Rappaport Institute, Technion, Haifa, Israel.
Mol Cell Neurosci. 2001 Aug;18(2):149-67. doi: 10.1006/mcne.2001.1012.
SAP90/PSD-95 is thought to be a central organizer of the glutamatergic synapse postsynaptic reception apparatus. To assess its potential role during glutamatergic synapse formation, we used GFP-tagged SAP90/PSD-95, time lapse confocal microscopy, and cultured hippocampal neurons to determine its dynamic recruitment into new synaptic junctions. We report that new SAP90/PSD-95 clusters first appeared at new axodendritic contact sites within 20-60 min of contact establishment. SAP90/PSD-95 clustering was rapid, with kinetics that fit a single exponential with a mean time constant of approximately 23 min. Most new SAP90/PSD-95 clusters were found juxtaposed to functional presynaptic boutons as determined by labeling with FM 4-64. No evidence was found for the existence of discrete transport particles similar to those previously reported to mediate presynaptic active zone cytoskeleton assembly. Instead, we found that SAP90/PSD-95 is recruited to nascent synapses from a diffuse dendritic cytoplasmic pool. Our findings show that SAP90/PSD-95 is recruited to nascent synaptic junctions early during the assembly process and indicate that its assimilation is fundamentally different from that of presynaptic active zone components.
SAP90/PSD - 95被认为是谷氨酸能突触后接收装置的核心组织者。为了评估其在谷氨酸能突触形成过程中的潜在作用，我们使用了绿色荧光蛋白标记的SAP90/PSD - 95、延时共聚焦显微镜以及培养的海马神经元来确定其动态募集到新突触连接中的情况。我们报告称，新的SAP90/PSD - 95簇在接触建立后的20 - 60分钟内首次出现在新的轴突 - 树突接触部位。SAP90/PSD - 95的聚集迅速，其动力学符合单指数形式，平均时间常数约为23分钟。通过用FM 4 - 64标记确定，大多数新的SAP90/PSD - 95簇与功能性突触前终扣并列。未发现存在类似于先前报道的介导突触前活性区细胞骨架组装的离散运输颗粒的证据。相反，我们发现SAP90/PSD - 95是从弥散的树突细胞质池中募集到新生突触的。我们的研究结果表明，SAP90/PSD - 95在组装过程早期就被募集到新生突触连接中，并且表明其整合与突触前活性区成分的整合在根本上是不同的。
