hDREF regulates cell proliferation and expression of ribosomal protein genes
hDREF regulates cell proliferation and expression of ribosomal protein genes
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DOI：
10.1128/mcb.01462-06
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发表时间：
2007-03-01
影响因子：
5.3
通讯作者：
Hirose, Fumiko
中科院分区：
文献类型：
--
作者：
Yamashita, Daisuke;Sano, Yukako;Hirose, Fumiko
尽管核糖体蛋白（RP）是所有生物体中必需的细胞成分，但其基因表达在哺乳动物中的调节机制仍不清楚。我们已经确定，79 个人类 RP 基因中有 22 个在其转录起始位点上游 200 bp 区域内含有与人类 DREF（DNA 复制相关元件结合因子；hDREF）结合序列 (hDRE) 相似的序列。电泳凝胶迁移率变动分析和染色质免疫沉淀分析表明，hDREF 在体外和体内均与 RP 基因中的 hDRE 样序列结合。此外，瞬时荧光素酶测定表明，hDRE 样序列充当 RP 基因转录的阳性元件，并且发现表达 hDREF 的质粒的共转染可刺激 RP 基因启动子活性。与 hDREF 一样，RP 基因的表达在 G 晚期至 S 期期间增加，并且使用短发夹 RNA 介导的敲低来耗尽 hDREF 会降低正常人成纤维细胞中的 RP 基因表达和细胞增殖。 RPS6 基因的敲除也会导致细胞增殖受损。这些数据表明 hDREF 是细胞增殖的重要转录因子，在许多 RP 基因的细胞周期依赖性调节中发挥作用。
Although ribosomal proteins (RPs) are essential cellular constituents in all living organisms, mechanisms underlying regulation of their gene expression in mammals remain unclear. We have established that 22 out of 79 human RP genes contain sequences similar to the human DREF (DNA replication-related element-binding factor; hDREF) binding sequence (hDRE) within 200-bp regions upstream of their transcriptional start sites. Electrophoretic gel mobility shift assays and chromatin immunoprecipitation analysis indicated that hDREF binds to hDRE-like sequences in the RP genes both in vitro and in vivo. In addition, transient luciferase assays revealed that hDRE-like sequences act as positive elements for RP gene transcription and cotransfection of an hDREF-expressing plasmid was found to stimulate RP gene promoter activity. Like that of hDREF, expression of RP genes is increased during the late G, to S phases, and depletion of hDREF using short hairpin RNA-mediated knockdown decreased RP gene expression and cell proliferation in normal human fibroblasts. Knockdown of the RPS6 gene also resulted in impairment of cell proliferation. These data suggest that hDREF is an important transcription factor for cell proliferation which plays roles in cell cycle-dependent regulation of a number of RP genes.