Importin β1 Protein-mediated Nuclear Localization of Death Receptor 5 (DR5) Limits DR5/Tumor Necrosis Factor (TNF)-related Apoptosis-inducing Ligand (TRAIL)-induced Cell Death of Human Tumor Cells
Importin β1 Protein-mediated Nuclear Localization of Death Receptor 5 (DR5) Limits DR5/Tumor Necrosis Factor (TNF)-related Apoptosis-inducing Ligand (TRAIL)-induced Cell Death of Human Tumor Cells
复制标题
DOI：
10.1074/jbc.m111.309377
复制
发表时间：
2011-12-16
影响因子：
4.8
通讯作者：
Yagita, Hideo
中科院分区：
文献类型：
--
作者：
Kojima, Yuko;Nakayama, Masafumi;Yagita, Hideo
肿瘤坏死因子相关的凋亡诱导配体(TRAIL)/死亡受体5(DR5)介导的细胞死亡在肿瘤细胞和转化细胞的清除中起着重要作用。近年来，重组TRAIL和激动型抗DR5单抗相继问世，并应用于肿瘤治疗。然而，根据癌症的类型，TRAIL的敏感性据报道有所不同，一些肿瘤细胞对TRAIL介导的凋亡具有抵抗力。利用共聚焦显微镜，我们发现在HeLa和HepG2细胞中有大量的DR5定位于细胞核。此外，这些肿瘤细胞对TRAIL具有耐药性，而没有核DR5的DU145细胞对TRAIL高度敏感。通过免疫沉淀和Western印迹分析，我们发现DR5和Importinβ1在物理上是相关的，这表明核DR5是通过Importinβ1介导的核输入途径运输的。在DR5中发现了两个功能性的核定位信号，其突变取消了DR5在HeLa细胞中的核定位。此外，通过siRNA抑制Importinβ1的表达，阻止了DR5的核转运，导致细胞表面DR5表达上调，并增加了HeLa和HepG2细胞对TRAIL的敏感性。综上所述，我们的研究结果表明，Importin beta 1介导的DR5的核定位限制了DR5/TRAIL诱导的人肿瘤细胞的死亡，因此可以成为利用重组TRAIL和抗DR5抗体改善癌症治疗的新靶点。
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/death receptor 5 (DR5)-mediated cell death plays an important role in the elimination of tumor cells and transformed cells. Recently, recombinant TRAIL and agonistic anti-DR5 monoclonal antibodies have been developed and applied to cancer therapy. However, depending on the type of cancer, the sensitivity to TRAIL has been reportedly different, and some tumor cells are resistant to TRAIL-mediated apoptosis. Using confocal microscopy, we found that large amounts of DR5 were localized in the nucleus in HeLa and HepG2 cells. Moreover, these tumor cells were resistant to TRAIL, whereas DU145 cells, which do not have nuclear DR5, were highly sensitive to TRAIL. By means of immunoprecipitation and Western blot analysis, we found that DR5 and importin beta 1 were physically associated, suggesting that the nuclear DR5 was transported through the nuclear import pathway mediated by importin beta 1. Two functional nuclear localization signals were identified in DR5, the mutation of which abrogated the nuclear localization of DR5 in HeLa cells. Moreover, the nuclear transport of DR5 was also prevented by the knockdown of importin beta 1 using siRNA, resulting in the up-regulation of DR5 expression on the cell surface and an increased sensitivity of HeLa and HepG2 cells to TRAIL. Taken together, our findings suggest that the importin beta 1-mediated nuclear localization of DR5 limits the DR5/TRAIL-induced cell death of human tumor cells and thus can be a novel target to improve cancer therapy with recombinant TRAIL and anti-DR5 antibodies.