ALU TRANSCRIPTS - CYTOPLASMIC LOCALIZATION AND REGULATION BY DNA METHYLATION
ALU TRANSCRIPTS - CYTOPLASMIC LOCALIZATION AND REGULATION BY DNA METHYLATION
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DOI：
10.1093/nar/22.6.1087
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发表时间：
1994-03-25
影响因子：
14.9
通讯作者：
SCHMID, CW
中科院分区：
文献类型：
--
作者：
LIU, WM;MARAIA, RJ;SCHMID, CW
HeLa细胞中的全长Alu转录物通过使用逆转录酶的引物延伸来检测，并且还作为克隆的cDNA序列进行分析。这些转录物的5'端对应于RNA聚合酶III的转录起始位点，表明这些RNA是从其内部聚合酶III启动子转录的。在细胞质poly A+ RNA中发现的Alu转录物似乎被组织成RNP，如通过蔗糖梯度沉降测定的。与7SL RNA相比，Alu转录物以每个细胞约100至1000个拷贝存在，是罕见的。与之前的报道一致，甲基化抑制Pol III-指导的转录的Alu在体外，5-氮杂胞苷的HeLa细胞的治疗结果在Alu DNA低甲基化和增加的丰度的Alu转录。序列分析表明，许多不同的Alu重复，包括所有亚家族的成员是由Pol III在体内转录。Pol III定向转录物的cDNA序列与Pol III启动子元件的A盒完全匹配，而在其他Alu转录物中，该元件并不忠实地保守。
Full length Alu transcripts in HeLa cells are detected by primer extension using reverse transcriptase and are also analyzed as cloned cDNA sequences. The 5' end of these transcripts corresponds to the transcriptional start site for RNA polymerase III indicating that these RNAs are transcribed from their internal polymerase III promoters. The Alu transcripts found in cytoplasmic poly A+ RNAs appear to be organized into RNPs as assayed by sucrose gradient sedimentation. Present at about one hundred to one thousand copies per cell, the Alu transcripts are rare as compared to 7SL RNA. In agreement with previous reports that methylation inhibits Pol III-directed transcription of Alu in vitro, treatment of HeLa cells with 5-azacytidine results in Alu DNA hypomethylation and an increase in the abundance of the Alu transcript. Sequence analysis shows that many different Alu repeats including members of all subfamilies are transcribed by Pol III in vivo. cDNA sequences of the Pol III-directed transcripts exactly match the A box of the Pol III promoter element whereas in other Alu transcripts this element is not faithfully conserved.