Steward O, Davis L, Dotti C, Phillips L L, Rao A, Banker G
Department of Neuroscience, University of Virginia School of Medicine, Charlottesville 22908.
Mol Neurobiol. 1988 Winter;2(4):227-61. doi: 10.1007/BF02935634.
Recent studies have shown that protein synthetic machinery consisting of polyribosomes and associated membranous cisterns is selectively localized beneath synaptic sites on neurons. In the present paper, the role of this machinery in neuronal function will be considered. We will: 1. Summarize the studies that characterize the polyribosomes and define their associations with membranous cisterns. Taken together, these observations suggest the existence of a system for the synthesis and posttranslational processing of proteins at individual synaptic sites; 2. Review the evidence that the protein synthetic machinery is particularly prominent during the initial formation of synaptic contacts (during early development), and during lesion-induced synaptogenesis in mature animals. These observations have led to the hypothesis that the polyribosomes produce proteins that play a role in the formation of the synaptic junction; 3. Review evidence that supports the hypothesis that there is a local synthesis of protein within dendrites, as well as local glycosylation; 4. Describe the evidence suggesting that at least some of the protein constituents of the synaptic junction itself are synthesized locally; and 5. Describe our studies that reveal a mechanism for selective dendritic transport of RNA; this transport mechanism permits the delivery of RNA to postsynaptic sites throughout the dendritic arbor. We will advance the hypothesis that neurons position protein synthetic machinery together with the mRNA's that are appropriate for particular synapses beneath synaptic contact regions. At the synaptic site, this machinery could then direct the synthesis of particular proteins that are critical for synapse formation or maintenance. The positioning of protein synthetic machinery at postsynaptic sites permits a rapid local regulation of the production of key proteins by events at individual synapses.
最近的研究表明，由多核糖体和相关膜性池组成的蛋白质合成机制选择性地定位于神经元突触部位下方。在本文中，将探讨这种机制在神经元功能中的作用。我们将：1. 总结那些对多核糖体进行表征并确定其与膜性池关联的研究。综合这些观察结果表明，在单个突触部位存在一个蛋白质合成和翻译后加工系统；2. 回顾证据表明，蛋白质合成机制在突触接触的初始形成阶段（早期发育期间）以及成熟动物损伤诱导的突触形成过程中尤为突出。这些观察结果引发了这样的假设，即多核糖体产生的蛋白质在突触连接的形成中发挥作用；3. 回顾支持树突内存在蛋白质局部合成以及局部糖基化这一假设的证据；4. 描述表明突触连接本身至少一些蛋白质成分是局部合成的证据；5. 描述我们揭示RNA选择性树突运输机制的研究；这种运输机制允许将RNA输送到整个树突分支的突触后部位。我们将提出这样的假设，即神经元将蛋白质合成机制与适合特定突触的mRNA一起定位在突触接触区域下方。在突触部位，这种机制随后可以指导合成对突触形成或维持至关重要的特定蛋白质。蛋白质合成机制在突触后部位的定位允许通过单个突触处的事件对关键蛋白质的产生进行快速局部调节。
