Monomeric scAlu and nascent dimeric Alu RNAs induced by adenovirus are assembled into SRP9/14-containing RNPs in HeLa cells
Monomeric scAlu and nascent dimeric Alu RNAs induced by adenovirus are assembled into SRP9/14-containing RNPs in HeLa cells
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DOI：
10.1093/nar/24.21.4165
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发表时间：
1996-11-01
影响因子：
14.9
通讯作者：
Maraia, RJ
中科院分区：
文献类型：
--
作者：
Chang, DY;Hsu, K;Maraia, RJ
近1,000,000个Alu散布元素的拷贝数约占人类DNA的5%。Alu元件通过一种称为逆转录转座的过程引起基因中断，其中二聚体Alu RNA是假定的中间产物，二聚体Alu转录本是不稳定的，产生稳定的左侧单体scAlu RNA，其水平受到严格调控，病毒感染或细胞应激诱导Alu RNA导致二聚体Alu转录本的急剧增加，而scAlu RNA略有增加。二聚体Alu元件的每个单体与信号识别颗粒(SRP)的7SL RNA成分具有序列同源性。SRP蛋白SRP9/14也在与scAlu RNA的离散复合体中被发现，尽管二聚体Alu RNA是否与SRP9/14相关尚不清楚。在这里，我们发现抗人SRPS的抗血清可以同时沉淀scAlu RNA和二聚体Alu RNA，这些RNPs在腺病毒感染后积聚，而SRP9、SRP14、SRP54和7SL SRP RNA的水平不受影响。二聚体Alu RNA也与La蛋白相关，表明这些确实是新生RNA聚合酶III转录本。这份报告证明，诱导的Alu转录本在体内组装成含有SRP9/14的RNPs，而SRP水平没有变化。讨论了Alu RNA新陈代谢和进化的意义。
Nearly 1 000 000 copies of Alu interspersed elements comprise similar to 5% of human DNA. Alu elements cause gene disruptions by a process known as retrotransposition, in which dimeric Alu RNA is a presumed intermediate, Dimeric Alu transcripts are labile, giving rise to stable left monomeric scAlu RNAs whose levels are tightly regulated, Induction of Alu RNA by viral infection or cell stress leads to a dramatic increase in dimeric Alu transcripts, while scAlu RNA increases modestly. Each monomer of the dimeric Alu element shares sequence homology with the 7SL RNA component of the signal recognition particle (SRP). The SRP protein known as SRP9/14 is also found in a discrete complex with scAlu RNA, although whether dimeric Alu RNA is associated with SRP9/14 had been unknown. Here we show that antiserum to human SRPS immunoprecipitates both scAlu RNA and dimeric Alu RNAs and that these RNPs accumulate after adenovirus infection, while levels of SRP9, SRP14, SRP54 and 7SL SRP RNA are unaffected. Dimeric Alu RNAs are also associated with the La protein, indicating that these are indeed nascent RNA polymerase III transcripts. This report documents that induced Alu transcripts are assembled into SRP9/14-containing RNPs in vivo while SRP levels are unchanged. Implications for Alu RNA metabolism and evolution are discussed.