Functionally antagonistic sequences are required for normal autoregulation of Drosophila tra-2 pre-mRNA splicing
Functionally antagonistic sequences are required for normal autoregulation of Drosophila tra-2 pre-mRNA splicing
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DOI：
10.1093/nar/29.14.3012
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发表时间：
2001-07-15
影响因子：
14.9
通讯作者：
Mattox, W
中科院分区：
文献类型：
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作者：
Chandler, DS;McGuffin, ME;Mattox, W
在果蝇雄性种系中，功能性TRA-2蛋白的表达是通过一种负反馈机制来调节的，在这种负反馈机制中，特定的TRA-2异构体抑制TRA-2前mrna中MI内含子的剪接。我们之前已经表明，M1剪接抑制的机制在远亲果蝇物种之间是保守的。利用转基因蝇株，我们研究了对MI内含子两个保守特征突变调控的影响。我们的研究结果表明，依赖于tra -2的M1剪接抑制取决于次优非一致3'剪接位点的存在。用强剪接位点取代这个3‘剪接位点导致TRA-2独立剪接，而用不相关的弱3’剪接位点取代则与抑制相容，这表明降低的基础剪接效率对调控很重要。内含子内部的第二个保守元件被发现对于在通常不保留内含子的体细胞中有效的M1剪接至关重要。我们发现该元件的作用是增强剪接，并克服由内含子的次优3'剪接位点引起的效率降低。我们的研究结果表明，M1内含子中的拮抗元件共同作用，建立了一个允许TRA-2抑制剪接的环境，同时在没有抑制因子的情况下允许有效的剪接。
Expression of functional TRA-2 protein in the male germline of Drosophila is regulated through a negative feedback mechanism in which a specific TRA-2 isoform represses splicing of the MI intron in the TRA-2 pre-mRNA. We have previously shown that the mechanism of M1 splicing repression is conserved between distantly related Drosophila species. Using transgenic fly strains, we have examined the effects on regulation of mutations in two conserved features of the MI intron. Our results show that TRA-2-dependent repression of M1 splicing depends on the presence of a suboptimal non-consensus 3' splice site. Substitution of this 3' splice site with a strong splice site resulted in TRA-2 independent splicing, while substitution with an unrelated weak 3' splice site was compatible with repression, implying that reduced basal splicing efficiency is important for regulation. A second conserved element internal to the intron was found to be essential for efficient M1 splicing in the soma where the intron is not normally retained. We show that the role of this element is to enhance splicing and overcome the reduction in efficiency caused by the intron's suboptimal 3' splice site. Our results indicate that antagonistic elements in the M1 intron act together to establish a context that is permissive for repression of splicing by TRA-2 while allowing efficient splicing in the absence of a repressor.