Modulation of msl-2 5′ splice site recognition by Sex-lethal
Modulation of msl-2 5′ splice site recognition by Sex-lethal
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DOI：
10.1017/s1355838201010536
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发表时间：
2001-09-01
期刊：
影响因子：
4.5
通讯作者：
Valcárcel, J
中科院分区：
文献类型：
--
作者：
Förch, P;Merendino, L;Valcárcel, J
性别致死蛋白（SXL）通过抑制雄性特异性致死-2 （msl-2）转录物的剪接和随后的翻译来控制果蝇的剂量补偿。我们之前已经证明，SXL阻断U2辅助因子（U2AF）与受调节内含子3'剪接位点相关的聚嘧啶（Py）区结合。我们现在报道，SXL有效抑制剪接需要第二个富含嘧啶的序列，该序列在5'剪接位点的下游含有11个连续的尿嘧啶。补骨脂素介导的交联实验表明，SXL结合到这个富含尿嘧啶的序列抑制了HeLa核提取物中U1 snRNP对5'剪接位点的识别。我们还发现SXL干扰了TIA-1蛋白与富尿嘧啶拉伸的结合。由于TIA-1与该序列的结合对于U1 snRNP招募到msl-2 5‘剪接位点以及该pre-mRNA的剪接是必需的，因此我们提出SXL拮抗TIA-1活性，从而阻止U1 snRNP识别5’剪接位点。结合先前的数据，我们得出结论，msl-2内含子的有效保留涉及抑制SXL对两个剪接位点的早期识别。
The protein Sex-lethal (SXL) controls dosage compensation in Drosophila by inhibiting splicing and subsequently translation of male-specific-lethal-2 (msl-2) transcripts. We have previously shown that SXL blocks the binding of U2 auxiliary factor (U2AF) to the polypyrimidine (Py)-tract associated with the 3' splice site of the regulated intron. We now report that a second pyrimidine-rich sequence containing 11 consecutive uridines immediately downstream from the 5' splice site is required for efficient splicing inhibition by SXL. Psoralen-mediated crosslinking experiments suggest that SXL binding to this uridine-rich sequence inhibits recognition of the 5' splice site by U1 snRNP in HeLa nuclear extracts. We also show that SXL interferes with the binding of the protein TIA-1 to the uridine-rich stretch. Because TIA-1 binding to this sequence is necessary for U1 snRNP recruitment to msl-2 5' splice site and for splicing of this pre-mRNA, we propose that SXL antagonizes TIA-1 activity and thus prevents 5' splice site recognition by U1 snRNP. Taken together with previous data, we conclude that efficient retention of msl-2 intron involves inhibition of early recognition of both splice sites by SXL.