Yasumoto Ken-ichi, Kowata Yusuke, Yoshida Atsushi, Torii Satoru, Sogawa Kazuhiro
Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
Biochim Biophys Acta. 2009 May;1793(5):792-7. doi: 10.1016/j.bbamcr.2009.01.014. Epub 2009 Feb 5.
Hypoxia-inducible factor-1 (HIF-1) is a major transcription factor regulating the response of tumor cells to hypoxia and is comprised of HIF-1alpha and Arnt (HIF-1beta). In mammalian cells, HIF-1 protein levels are regulated by three HIF-prolyl hydroxylases, termed PHD1, PHD2 and PHD3. To assess whether intracellular localization of PHD1 and PHD2 affects the hypoxic response via HIF-1, we investigated the localization signal of PHDs. PHD1 possessed at least one nuclear localization signal (NLS), and PHD2 contained a region as essential for nuclear export in their N-terminal region. Treatment of cells with leptomycin B revealed that PHD2 was able to shuttle between the cytoplasm and the nucleus. Reporter assay indicated that differences in the intracellular distribution of PHD1 did not influence on HIF-1alpha activity. However, a PHD2 mutant lacking the region for nuclear export exhibited significantly reduced effect to HIF-1alpha activity compared to wild-type PHD2, suggesting that the regulation of the intracellular distribution of PHD2 is an effective pathway for the control of the hypoxic response.
缺氧诱导因子-1（HIF-1）是一种主要的转录因子，可调节肿瘤细胞对缺氧的反应，由HIF-1α和芳烃受体核转运蛋白（Arnt，即HIF-1β）组成。在哺乳动物细胞中，HIF-1蛋白水平受三种HIF脯氨酰羟化酶（称为PHD1、PHD2和PHD3）调节。为了评估PHD1和PHD2的细胞内定位是否通过HIF-1影响缺氧反应，我们研究了PHD的定位信号。PHD1至少具有一个核定位信号（NLS），而PHD2在其N端区域含有一个对核输出至关重要的区域。用放线菌素B处理细胞表明，PHD2能够在细胞质和细胞核之间穿梭。报告基因检测表明，PHD1细胞内分布的差异不影响HIF-1α活性。然而，与野生型PHD2相比，缺乏核输出区域的PHD2突变体对HIF-1α活性的影响显著降低，这表明调节PHD2的细胞内分布是控制缺氧反应的有效途径。
