Nuclear-cytoplasmic shuttling of a RING-IBR protein RBCK1 and its functional interaction with nuclear body proteins
Nuclear-cytoplasmic shuttling of a RING-IBR protein RBCK1 and its functional interaction with nuclear body proteins
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DOI：
10.1074/jbc.m413476200
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发表时间：
2005-06-17
影响因子：
4.8
通讯作者：
Kuroda, S
中科院分区：
文献类型：
--
作者：
Tatematsu, K;Yoshimoto, N;Kuroda, S
具有 DNA 结合和转录活性的 RING-IBR 蛋白 RBCK1 的细胞内定位已被研究。内源性 RBCK1 存在于细胞质和细胞核中。特别是在细胞核中，它位于颗粒结构中，最有可能是核体。相反，过度表达的 RBCK1 仅在细胞质中检测到。当用leptomycin B处理细胞时，过表达的RBCK1在核体中积累。这些结果表明 RBCK1 拥有负责核-胞质易位的信号序列。 RBCK1的突变分析表明，含有Leu-142和Leu-145的N端区域和含有RING-IBR结构域的C端区域分别充当核输出和定位信号。因此，RBCK1是一种在细胞质和细胞核之间动态穿梭的转录因子。此外，还发现 RBCK1 与核体蛋白、CREB 结合蛋白 (CBP) 和早幼粒细胞白血病蛋白 (PML) 相互作用。 RBCK1与CBP的共表达显着增强了RBCK1的转录活性。尽管 PML 本身对 RBCK1 的转录活性没有影响，但 CBP 增强的活性受到与 PML 共表达的抑制，大概是通过 PML 和 CBP 的相互作用。综上所述，我们的数据表明 RBCK1 参与核体中的转录机制，并且其转录活性受到核质穿梭的调节。
The intracellular localization of a RING-IBR protein, RBCK1, possessing DNA binding and transcriptional activities, has been investigated. The endogenous RBCK1 was found in both the cytoplasm and nucleus. Particularly in the nucleus, it was localized in the granular structures, most likely nuclear bodies. In contrast, the over-expressed RBCK1 was detected exclusively in the cytoplasm. When the cells were treated with leptomycin B, the over-expressed RBCK1 accumulated in the nuclear bodies. These results suggest that RBCK1 possesses the signal sequences responsible for the nuclear-cytoplasmic translocation. Mutational analysis of RBCK1 has indicated that an N-terminal region containing Leu-142 and Leu-145 and a C-terminal one containing the RING-IBR domain serve as the nuclear export and localization signals, respectively. Thus, RBCK1 is a transcription factor dynamically shuttling between cytoplasm and nucleus. Furthermore, RBCK1 was found to interact with nuclear body proteins, CREB-binding protein (CBP), and promyelocytic leukemia protein (PML). Coexpression of RBCK1 with CBP significantly enhanced the transcriptional activity of RBCK1. Although PML per se showed no effect on the transcriptional activity of RBCK1, the CBP-enhanced activity was repressed by coexpression with PML, presumably through the interaction of PML and CBP. Taken together, our data demonstrate that RBCK1 is involved in transcriptional machinery in the nuclear bodies, and its transcriptional activity is regulated by nucleocytoplasmic shuttling.