SR proteins and hnRNP H regulate the splicing of the HIV-1 tev-specific exon 6D
SR proteins and hnRNP H regulate the splicing of the HIV-1 tev-specific exon 6D
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DOI：
10.1093/emboj/21.4.845
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发表时间：
2002-02-15
期刊：
影响因子：
11.4
通讯作者：
Zahler, AM
中科院分区：
文献类型：
--
作者：
Caputi, M;Zahler, AM
HIV-1 env基因的一个自然出现的点突变激活了隐蔽外显子6D的异常包含在大多数Aral消息中，导致病毒复制效率低下。我们开始了解单核苷酸替换是如何导致剪接发生如此戏剧性的变化的。我们已经确定，外显子6D突变促进了SR蛋白SC35与外显子的结合。突变的外显子6D序列在插入增强子依赖的剪接结构时起到剪接增强剂的作用。HnRNP H家族蛋白也与增强子结合；它们的结合依赖于位于点突变下游的GGGA序列，耗竭-重组研究表明hnRNP H是增强子活性所必需的。位于外显子6D下游的多嘌呤序列与SR蛋白结合，但起外显子剪接沉默的作用。HnRNP H是U1与增强子相互作用所必需的，与点突变无关。我们认为，SC35与点突变区域的结合可能会将hnRNP H-U1 SnRNP复合体转化为剪接增强子。
A naturally arising point mutation in the env gene of HIV-1 activates the aberrant inclusion of the cryptic exon 6D into most Aral messages, leading to inefficient viral replication. We set out to understand how a single nucleotide substitution could cause such a dramatic change in splicing. We have determined that the exon 6D mutation promotes binding of the SR protein SC35 to the exon. Mutant exon 6D sequences function as a splicing enhancer when inserted into an enhancer-dependent splicing construct. hnRNP H family proteins bind to the enhancer as well; their binding is dependent on the sequence GGGA located just downstream of the point mutation and depletion-reconstitution studies show that hnRNP H is essential for enhancer activity. A polypurine sequence located further downstream in exon 6D binds SR proteins but acts as an exonic splicing silencer. hnRNP H is required for interaction of U1 snRNP with the enhancer, independent of the point mutation. We propose that SC35 binding to the point mutation region may convert the hnRNP H-U1 snRNP complex into a splicing enhancer.