Public Health Research Institute and Department of Microbiology and Molecular Genetics, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.
Proc Natl Acad Sci U S A. 2012 Mar 20;109(12):4645-50. doi: 10.1073/pnas.1111226109. Epub 2012 Mar 5.
RNA transport granules deliver translationally repressed mRNAs to synaptic sites in dendrites, where synaptic activity promotes their localized translation. Although the identity of many proteins that make up the neuronal granules is known, the stoichiometry of their core component, the mRNA, is poorly understood. By imaging nine different dendritically localized mRNA species with single-molecule sensitivity and subdiffraction-limit resolution in cultured hippocampal neurons, we show that two molecules of the same or different mRNA species do not assemble in common structures. Even mRNA species with a common dendritic localization element, the sequence that is believed to mediate the incorporation of these mRNAs into common complexes, do not colocalize. These results suggest that mRNA molecules traffic to the distal reaches of dendrites singly and independently of others, a model that permits a finer control of mRNA content within a synapse for synaptic plasticity.
RNA 运输颗粒将翻译受到抑制的 mRNAs 递送至树突中的突触部位，在突触部位，突触活动促进其局部翻译。尽管许多构成神经元颗粒的蛋白质的身份已经知晓，但它们的核心成分——mRNA 的化学计量学仍知之甚少。通过在培养的海马神经元中以单分子灵敏度和亚衍射极限分辨率对九种不同的定位于树突的 mRNA 进行成像，我们表明相同或不同 mRNA 物种的两个分子不会组装在共同的结构中。甚至具有共同树突定位元件的 mRNA 物种（被认为介导这些 mRNAs 掺入共同复合物的序列）也不会共定位。这些结果表明，mRNA 分子单独且独立地运输到树突的远端，这种模型允许在突触内更精细地控制 mRNA 含量，以实现突触可塑性。
