Miki Takashi, Takano Keizo, Yoneda Yoshihiro
Department of Cell Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
Cell Struct Funct. 2005;30(2):51-6. doi: 10.1247/csf.30.51.
The localization of mRNA in neuronal dendrites plays a role in both locally and temporally regulated protein synthesis, which is required for certain forms of synaptic plasticity. RNA granules constitute a dendritic mRNA transport machinery in neurons, which move along microtubules. RNA granules contain densely packed clusters of ribosomes, but lack some factors that are required for translation, suggesting that they are translationally incompetent. Recently some of the components of RNA granules have been identified, and their functions are in the process of being examined, in attempts to better understand the properties of RNA granules. Mammalian Staufen, a double-stranded RNA binding protein, is a component of RNA granules. Staufen is localized in the somatodendritic domain of neurons, and plays an important role in dendritic mRNA targeting. Recently, one of the mammalian homologs of Staufen, Staufen2 (Stau2), was shown to shuttle between the nucleus and the cytoplasm. This finding suggests the possibility that Stau2 binds RNA in the nucleus and that this ribonucleoprotein particle is transported from the nucleus to RNA granules in the cytoplasm. A closer study of this process might provide a clue to the mechanism by which RNA granules are formed.
mRNA在神经元树突中的定位在局部和时间调控的蛋白质合成中均发挥作用，而这种蛋白质合成是某些形式的突触可塑性所必需的。RNA颗粒构成了神经元中的一种树突mRNA转运机制，其沿着微管移动。RNA颗粒包含紧密堆积的核糖体簇，但缺乏一些翻译所需的因子，这表明它们无翻译能力。最近，RNA颗粒的一些成分已被鉴定出来，其功能正在研究之中，以期更好地了解RNA颗粒的特性。哺乳动物中的双链RNA结合蛋白Staufen是RNA颗粒的一个成分。Staufen定位于神经元的胞体树突区域，并在树突mRNA靶向中发挥重要作用。最近，Staufen的一个哺乳动物同源物Staufen2（Stau2）被证明在细胞核和细胞质之间穿梭。这一发现提示了Stau2在细胞核中结合RNA并将这种核糖核蛋白颗粒从细胞核转运至细胞质中的RNA颗粒的可能性。对这一过程进行更深入的研究可能会为RNA颗粒形成的机制提供线索。
