Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Neuron. 2011 Mar 10;69(5):877-84. doi: 10.1016/j.neuron.2011.02.028.
RNA precursors give rise to mRNA after splicing of intronic sequences traditionally thought to occur in the nucleus. Here, we show that intron sequences are retained in a number of dendritically-targeted mRNAs, by using microarray and Illumina sequencing of isolated dendritic mRNA as well as in situ hybridization. Many of the retained introns contain ID elements, a class of SINE retrotransposon. A portion of these SINEs confers dendritic targeting to exogenous and endogenous transcripts showing the necessity of ID-mediated mechanisms for the targeting of different transcripts to dendrites. ID elements are capable of selectively altering the distribution of endogenous proteins, providing a link between intronic SINEs and protein function. As such, the ID element represents a common dendritic targeting element found across multiple RNAs. Retention of intronic sequence is a more general phenomenon than previously thought and plays a functional role in the biology of the neuron, partly mediated by co-opted repetitive sequences.
RNA 前体在剪接内含子序列后产生 mRNA，传统上认为内含子序列的剪接发生在细胞核内。在这里，我们通过对分离的树突状 mRNA 进行微阵列和 Illumina 测序以及原位杂交，显示了许多树突状靶向的 mRNA 中保留了内含子序列。许多保留的内含子包含 ID 元件，这是一类 SINE 反转录转座子。这些 SINE 中的一部分赋予了外源性和内源性转录本的树突状靶向，表明 ID 介导的机制对于不同转录本向树突的靶向是必要的。ID 元件能够选择性地改变内源性蛋白的分布，为内含子 SINE 与蛋白功能之间建立了联系。因此，ID 元件代表了在多种 RNA 中发现的常见的树突状靶向元件。内含子序列的保留是一种比以前认为的更为普遍的现象，在神经元的生物学中发挥着功能作用，部分是由被篡夺的重复序列介导的。
