First come, first served revisited: Factors affecting the same alternative splicing event have different effects on the relative rates of intron removal
First come, first served revisited: Factors affecting the same alternative splicing event have different effects on the relative rates of intron removal
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DOI：
10.1261/rna.1993510
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发表时间：
2010-05-01
期刊：
影响因子：
4.5
通讯作者：
Kornblihtt, Alberto R.
中科院分区：
文献类型：
--
作者：
de la Mata, Manuel;Lafaille, Celina;Kornblihtt, Alberto R.
在高等真核生物中，可变剪接占了大部分的复杂性。因此，其监管必须允许灵活性，而不妨碍其具体性或忠实性。选择性剪接调控的机制，特别是通过与转录偶联起作用的机制，尚未在体内模型中深入研究。我们的大部分知识来自体外方法，其中条件可以精确控制，代价是失去完整细胞中存在的几个调节水平。在这里，我们研究了删除的内含子侧翼的模型选择盒外显子的相对顺序。我们发现，有一个优先删除的内含子下游盒外显子上游内含子被删除之前。最重要的是，顺式作用突变和反式作用因子，调节模型选择性剪接事件差异影响的相对顺序删除。然而，转录延长的减少导致更高的包含盒外显子不改变内含子去除的顺序，这表明，假设，根据“先到先得”的模型，即缓慢的延长促进上游内含子的优先切除必须进行修改。相反，我们建议，缓慢的延伸有利于承诺外显子包含在剪接体组装。我们的研究结果表明，测量内含子去除的顺序可能是一个简单的读出来区分不同的选择性剪接位点选择机制。
Alternative splicing accounts for much of the complexity in higher eukaryotes. Thus, its regulation must allow for flexibility without hampering either its specificity or its fidelity. The mechanisms involved in alternative splicing regulation, especially those acting through coupling with transcription, have not been deeply studied in in vivo models. Much of our knowledge comes from in vitro approaches, where conditions can be precisely controlled at the expense of losing several levels of regulation present in intact cells. Here we studied the relative order of removal of the introns flanking a model alternative cassette exon. We show that there is a preferential removal of the intron downstream from the cassette exon before the upstream intron has been removed. Most importantly, both cis-acting mutations and trans-acting factors that regulate the model alternative splicing event differentially affect the relative order of removal. However, reduction of transcriptional elongation causing higher inclusion of the cassette exon does not change the order of intron removal, suggesting that the assumption, according to the "first come, first served'' model, that slow elongation promotes preferential excision of the upstream intron has to be revised. We propose instead that slow elongation favors commitment to exon inclusion during spliceosome assembly. Our results reveal that measuring the order of intron removal may be a straightforward read-out to discriminate among different mechanisms of alternative splice site selection.