Cristofanilli Massimiliano, Thanos Solon, Brosius Jürgen, Kindler Stefan, Tiedge Henri
Department of Physiology and Pharmacology, State University of New York, Health Science Center at Brooklyn, 11203, USA.
J Mol Biol. 2004 Aug 20;341(4):927-34. doi: 10.1016/j.jmb.2004.06.045.
Providing the basis for local protein synthesis in dendritic microdomains, RNA transport in dendrites is thought to be underlying long-term neuronal plasticity. Dendritic RNA targeting mechanisms can therefore be expected to confer selective advantages in the evolution of complex neural systems. The question thus arises as to when and how dendritically targeted transcripts first acquired their targeting competence. To address this question, the dendritic targeting competence of MAP2 transcripts was examined in chicken, mouse and rat. In one approach, we established the somato-dendritic distribution of MAP2 transcripts in vivo. We found that in contrast to rodent MAP2 mRNAs, which are highly enriched in dendritic regions of the retina, chicken MAP2 transcripts are virtually absent from such areas and are rather confined to neuronal somata. In an independent line of investigation, we determined that a dendritic targeting element (DTE) corresponding to the mammalian MAP2 DTE is not contained in the 3' untranslated region (UTR) of avian MAP2 mRNA. The combined results indicate that in contrast to mammalian MAP2 transcripts, avian MAP2 mRNA is lacking dendritic targeting competence. The data thus suggest that the acquisition of such competence has likely been a relatively recent event in evolution.
树突微域中局部蛋白质合成的基础是树突中的RNA运输，它被认为是长期神经元可塑性的基础。因此，树突RNA靶向机制有望在复杂神经系统的进化中赋予选择性优势。于是就出现了这样一个问题：树突靶向转录本最初是在何时以及如何获得其靶向能力的。为了解决这个问题，我们研究了鸡、小鼠和大鼠中MAP2转录本的树突靶向能力。在一种方法中，我们确定了体内MAP2转录本的胞体-树突分布。我们发现，与在视网膜树突区域高度富集的啮齿动物MAP2 mRNA不同，鸡的MAP2转录本在这些区域几乎不存在，而是局限于神经元胞体。在另一项独立的研究中，我们确定禽MAP2 mRNA的3'非翻译区（UTR）中不包含与哺乳动物MAP2 DTE相对应的树突靶向元件（DTE）。综合结果表明，与哺乳动物MAP2转录本不同，禽MAP2 mRNA缺乏树突靶向能力。因此，数据表明获得这种能力可能是进化中相对较新的事件。
