Laboratory of Eukaryotic Genome Evolution, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia.
Gene. 2010 Feb 1;451(1-2):32-7. doi: 10.1016/j.gene.2009.11.007. Epub 2009 Nov 14.
4.5S(I) RNA is a small nuclear RNA synthesized by RNA polymerase III and detected in rodents of only four families. Hundreds of copies of this RNA retropseudogenes are interspersed throughout the mouse (Mus musculus) and rat (Rattus norvegicus) genomes. We found a single locus containing 4.5S(I) RNA genes in the genomes of these rodents. The locus harbors three genes and occupies 80 kb on M. musculus chromosome 6 and 44 kb on R. norvegicus chromosome 4. Two long duplications seem to have taken place during evolution of this locus. Two mouse 4.5S(I) RNA genes were used for a study of the role of 5'-flanking sequences in transcription in vitro and ex vivo. We found that removal of these DNA sequences resulted in a dramatic reduction of transcription though an internal promoter for RNA polymerase III was preserved in 4.5S(I) RNA genes. Thus, 5'-flanking sequences (from -1 to -90) containing conserved regions are important for 4.5S(I) RNA gene expression.
4.5S(I)RNA 是一种由 RNA 聚合酶 III 合成的小核 RNA，仅在四个科的啮齿动物中检测到。这种 RNA 的数百个逆转录假基因散布在小鼠（Mus musculus）和大鼠（Rattus norvegicus）基因组中。我们在这些啮齿动物的基因组中发现了一个包含 4.5S(I)RNA 基因的单一基因座。该基因座包含三个基因，在 M. musculus 染色体 6 上占据 80kb，在 R. norvegicus 染色体 4 上占据 44kb。在这个基因座的进化过程中，似乎发生了两次长重复。两个小鼠 4.5S(I)RNA 基因被用于研究 5'-侧翼序列在体外和体内转录中的作用。我们发现，尽管 RNA 聚合酶 III 的内部启动子在 4.5S(I)RNA 基因中得以保留，但去除这些 DNA 序列会导致转录显著减少。因此，包含保守区域的 5'-侧翼序列（从-1 到-90）对于 4.5S(I)RNA 基因的表达很重要。
