POLYPURINE SEQUENCES WITHIN A DOWNSTREAM EXON FUNCTION AS A SPLICING ENHANCER
POLYPURINE SEQUENCES WITHIN A DOWNSTREAM EXON FUNCTION AS A SPLICING ENHANCER
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DOI：
10.1128/mcb.14.2.1347
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发表时间：
1994-02-01
影响因子：
5.3
通讯作者：
SHIMURA, Y
中科院分区：
文献类型：
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作者：
TANAKA, K;WATAKABE, A;SHIMURA, Y
我们以前已经证明，位于小鼠免疫球蛋白MU基因外显子M2内的富嘌呤序列具有剪接增强剂的功能，这是通过刺激远端上游内含子的剪接来判断的。该序列元件被命名为ERS(外显子识别序列)。在这项研究中，我们使用HeLa细胞核提取物的体外剪接系统，研究了不同的ERS样序列的刺激作用。在这里，我们展示了几个先前被证明是剪接所需的自然外显子的富嘌呤序列作为剪接增强剂发挥功能，就像免疫球蛋白Mu基因的ERS一样。此外，即使是合成的多嘌呤序列也对上游剪接有刺激作用。对从天然和合成的富嘌呤序列的分析获得的数据的评估表明：(I)交替的嘌呤序列可以刺激剪接，而聚(A)或聚(G)序列不能，以及(Ii)多嘌呤序列中U残基的存在大大降低了刺激水平。竞争实验有力地表明，不同的富嘌呤序列的刺激作用是由相同的反式作用因子介导的(S)。从这些结果我们得出结论，我们在这项研究中检查的富嘌呤序列也代表了ERS的例子。因此，ERS被认为是一种普遍存在的剪接元件，存在于各种外显子中，在剪接位点的选择中发挥着重要作用。
We have previously shown that a purine-rich sequence located within exon M2 of the mouse immunoglobulin mu gene functions as a splicing enhancer, as judged by its ability to stimulate splicing of a distant upstream intron. This sequence element has been designated ERS (exon recognition sequence). In this study, we investigated the stimulatory effects of various ERS-like sequences, using the in vitro splicing system with HeLa cell nuclear extracts. Here, we show that purine-rich sequences of several natural exons that have previously been shown to be required for splicing function as a splicing enhancer like the ERS of the immunoglobulin mu gene. Moreover, even synthetic polypurine sequences had stimulatory effects on the upstream splicing. Evaluation of the data obtained from the analyses of both natural and synthetic purine-rich sequences shows that (i) alternating purine sequences can stimulate splicing, while poly(A) or poly(G) sequences cannot, and (ii) the presence of U residues within the polypurine sequence greatly reduces the level of stimulation. Competition experiments strongly suggest that the stimulatory effects of various purine-rich sequences are mediated by the same trans-acting factor(s). We conclude from these results that the purine-rich sequences that we examined in this study also represent examples of ERS. Thus, ERS is considered a general splicing element that is present in various exons and plays an important role in splice site selection.