Mitochondrial and nuclear localization of human Pif1 helicase
Mitochondrial and nuclear localization of human Pif1 helicase
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DOI：
10.1248/bpb.30.1685
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发表时间：
2007-09-01
影响因子：
2
通讯作者：
Furuichi, Yasuhiro
中科院分区：
文献类型：
--
作者：
Futami, Kazunobu;Shimamoto, Akira;Furuichi, Yasuhiro
酵母Pif1 DNA解旋酶是参与端粒、核糖体和线粒体DNA维持的解旋酶亚家族的原型成员。从酵母到人类，Pif1 DNA解旋酶家族是高度保守的，但人类同源物的生化性质仍有待阐明。为此，我们研究了人类Pif1基因的转录单位及其编码蛋白hif1。结果表明，hpi1基因产物至少有两个同工型，包括保守的解旋酶基序和由基因转录物的选择性剪接产生的差异c端区域。缺失突变体分析表明，Pif1解旋酶在n端和c端分别具有核定位信号和线粒体靶向信号。在HeLa细胞中，hhpif1解旋酶的表达是由细胞从血清饥饿中释放诱导的，这表明hhpif1在S期有作用。与此一致的是，RNA干扰siRNA对hpi1解旋酶的下调导致细胞周期在S期延迟。这些发现提示，细胞核中的hPif1可能参与与DNA复制相关的染色体维持，而hPif1的功能仍有待阐明。
Yeast Pif1 DNA helicase is the prototype member of a helicase subfamily participating in the maintenance of telomere, ribosome, and mitochondria DNAs. The Pif1 DNA helicase family is highly conserved from yeast to human, but the biochemical nature of human homologues remains to be clarified. To this end, we investigated the transcriptional unit of human Pif1 gene and its encoded protein hPif1. The results showed that the hPif1 gene product has at least two isoforms consisting of the conserved helicase motif and differential C-terminal regions derived from alternative splicing of the gene transcript. Deletion mutant analysis showed that Pif1 helicase has nuclear localization signal and mitochondria targeting signal at the N-terminal and C-terminal regions, respectively. In HeLa cells, hPif1 helicase expression was induced by the release of cells from serum starvation, suggesting that hPif1 has roles in the S phase. Consistently, the down regulation of the hPif1 helicase by RNA interference with siRNA caused a cell cycle delay at the S phase. These findings suggest that hPif1 in the nucleus may be involved in chromosome maintenance in association with DNA replication, while the function of hPif1 remains to be clarified.