Umylny Boris, Presting Gernot, Ward W Steven
Asia Pacific Bioinformatics Research Institute, Honolulu, HI, USA.
Arch Androl. 2007 Jul-Aug;53(4):207-18. doi: 10.1080/01485010701426422.
Alus and B1s are short interspersed repeat elements (SINEs) derived from the 7SL RNA gene. Alus and B1s exist in the cytoplasm as non-coding RNA indicating that they are actively transcribed, but their function, if any, is unknown. Transcription of individual SINEs is a prerequisite for retroposition, but it is also possible that individual Alu and B1 elements have some cellular functions. Previous studies suggest that transcription of Alu elements depends on the presence of an RNA polymerase-III bipartite promoter and the poly-A tail. Sequencing of small RNAs has demonstrated that the members of the Y and S subfamily are expressed. We analyzed almost one million Alu sequences longer than 200 nucleotides for the presence of RNA polymerase-III bipartite promoter sequences. More than half contained a promoter indicating some potential for expression. We searched 7.7 million human EST sequences in dbEST for the presence of Alu non-coding RNAs and found evidence for the expression of 452. Analysis of mouse spermatogenic dbEST libraries revealed an apparent relationship between the level of differentiation and the level of B1-related sequences in the EST library.
Alu元件和B1元件是源自7SL RNA基因的短散在重复元件（SINEs）。Alu元件和B1元件以非编码RNA的形式存在于细胞质中，这表明它们在活跃转录，但其功能（如果有）尚不清楚。单个SINEs的转录是逆转座的前提条件，但单个Alu元件和B1元件也可能具有某些细胞功能。先前的研究表明，Alu元件的转录取决于RNA聚合酶III二分启动子和多聚A尾的存在。小RNA测序表明Y亚家族和S亚家族的成员都有表达。我们分析了近100万个长度超过200个核苷酸的Alu序列，以寻找RNA聚合酶III二分启动子序列的存在情况。超过一半的序列含有启动子，表明有一定的表达潜力。我们在dbEST中搜索了770万条人类EST序列，以寻找Alu非编码RNA的存在证据，并发现了452条表达证据。对小鼠生精dbEST文库的分析揭示了EST文库中分化水平与B1相关序列水平之间的明显关系。
