Division of Cell Biology, Biomedical Center, LMU Munich, Martinsried, Germany.
Department of Molecular Neuroscience, University College London Institute of Neurology, London, UK.
EMBO Rep. 2017 Oct;18(10):1762-1774. doi: 10.15252/embr.201744334. Epub 2017 Aug 1.
Dendritic localization and hence local mRNA translation contributes to synaptic plasticity in neurons. Staufen2 (Stau2) is a well-known neuronal double-stranded RNA-binding protein (dsRBP) that has been implicated in dendritic mRNA localization. The specificity of Stau2 binding to its target mRNAs remains elusive. Using individual-nucleotide resolution CLIP (iCLIP), we identified significantly enriched Stau2 binding to the 3'-UTRs of 356 transcripts. In 28 (7.9%) of those, binding occurred to a retained intron in their 3'-UTR The strongest bound 3'-UTR intron was present in the longest isoform of ( ) mRNA 3'-UTR contains six Stau2 crosslink clusters, four of which are in this retained 3'-UTR intron. The mRNA localized to neuronal dendrites, while lack of the 3'-UTR intron impaired its dendritic localization. Importantly, Stau2 mediates this dendritic localization via the 3'-UTR intron, without affecting its stability. Also, NMDA-mediated synaptic activity specifically promoted the dendritic mRNA localization of the isoform, while inhibition of synaptic activity reduced it substantially. Together, our results identify the retained intron as a critical element in recruiting Stau2, which then allows for the localization of mRNA to distal dendrites.
树突定位，进而导致局部 mRNA 翻译，有助于神经元的突触可塑性。Staufen2（Stau2）是一种众所周知的神经元双链 RNA 结合蛋白（dsRBP），其与树突 mRNA 定位有关。Stau2 与其靶 mRNA 结合的特异性仍然难以捉摸。使用单核苷酸分辨率 CLIP（iCLIP），我们确定了 Stau2 与 356 个转录本的 3'-UTR 显著富集结合。在其中的 28 个（7.9%）中，结合发生在其 3'-UTR 中的一个保留内含子中。最强结合的 3'-UTR 内含子存在于 （）mRNA 的最长异构体中。 3'-UTR 包含六个 Stau2 交联簇，其中四个位于这个保留的 3'-UTR 内含子中。 mRNA 定位于神经元树突，而缺乏 3'-UTR 内含子则损害其树突定位。重要的是，Stau2 通过 3'-UTR 内含子介导这种树突定位，而不影响其稳定性。此外，NMDA 介导的突触活动特异性促进了 异构体的树突 mRNA 定位，而抑制突触活动则大大减少了它。总之，我们的结果确定了保留的内含子是招募 Stau2 的关键因素，Stau2 随后允许 mRNA 定位于远端树突。
