LINE-mediated retrotransposition of marked Alu sequences
LINE-mediated retrotransposition of marked Alu sequences
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DOI：
10.1038/ng1223
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发表时间：
2003-09-01
期刊：
影响因子：
30.8
通讯作者：
Heidmann, T
中科院分区：
文献类型：
--
作者：
Dewannieux, M;Esnault, C;Heidmann, T
Alu因子是人类中最成功的转座子。它们是由RNA聚合酶III （Pol III）转录的300 bp的非编码序列，预计将在细胞来源的逆转录酶的帮助下进行反转座。我们之前的研究表明，人类LINEs可以通过逆转录过程产生任何mRNA转录物的cDNA拷贝，该过程涉及line编码的内切酶和逆转录酶的反转录和整合。在这里，我们展示了人类HeLa细胞中标记Alu序列的移动性，具有典型的反转录过程特征，包括将自催化内含子剪接到标记序列中，不同长度的靶位点复制以及整合到一致的a -富序列中。我们进一步表明，Alu 3'端的poly-A延伸对于迁移是必不可少的，LINEs是转位所必需的，Alu转录本的逆转录率比对照mrna高100 - 1000倍，从而解释了在人类中观察到的这些元件的高突变活性。
Alu elements are the most successful transposons in humans. They are 300-bp non-coding sequences transcribed by RNA polymerase III (Pol III) and are expected to retrotranspose with the aid of reverse transcriptases of cellular origin. We previously showed that human LINEs can generate cDNA copies of any mRNA transcript by means of a retroposition process involving reverse transcription and integration by the LINE-encoded endonuclease and reverse transcriptase. Here we show mobility of marked Alu sequences in human HeLa cells with the canonical features of a retrotransposition process, including splicing out of an autocatalytic intron introduced into the marked sequence, target site duplications of varying lengths and integrations into consensus A-rich sequences. We further show that the poly-A stretch at the Alu 3' end is essential for mobility, that LINEs are required for transposition and that the rate of retroposition is 100 1,000 times higher for Alu transcripts than for control mRNAs, thus accounting for the high mutational activity of these elements observed in humans.