Nuclear translocation of the pro-apoptotic Bcl-2 family member Bok induces apoptosis
Nuclear translocation of the pro-apoptotic Bcl-2 family member Bok induces apoptosis
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DOI：
10.1002/mc.20156
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发表时间：
2006-02-01
影响因子：
4.6
通讯作者：
Hung, MC
中科院分区：
文献类型：
--
作者：
Bartholomeusz, G;Wu, Y;Hung, MC
Bcl-2 家族的抗凋亡成员，例如 Bcl-2 和 Bcl-XL，通过内在凋亡途径在防止细胞凋亡诱导中发挥核心作用。先前已表明，促凋亡 Bcl-2 家族成员 Bok 诱导细胞凋亡不会被 Bcl-2 或 BCl-x(L) 拮抗，这表明 Bok 可能在细胞凋亡级联中具有独特的作用。我们在此表明，人类 Bok 是 Bcl-2 家族中唯一具有富含亮氨酸序列的成员，表明其 BH3 结构域内存在核输出信号。对细胞核和细胞质组分的蛋白质印迹分析发现，HEK 293T 细胞、HeLa 细胞和乳腺癌细胞的细胞核和细胞质中均存在 Bok，并且用 Leptomycin 3（一种 Crm1 输出蛋白抑制剂）处理这些细胞后，其细胞核浓度增加。标记 Bok 的免疫细胞化学证实了其核定位。通过定点诱变突变 Bok 的核输出信号导致其核定位和凋亡活性增加。我们还发现 Crm1 与野生型 Bok 相互作用，但不与突变型 Bok 相互作用。这些结果表明，Bok 的核输出是一个由 Crml 介导的调节过程，并且首次报道了 Bc1-2 家族促凋亡成员的凋亡活性与核定位之间的联系。 (c) 2005 年 Wiley-Liss, Inc.
The anti-apoptotic members of the Bcl-2 family, such as Bcl-2 and Bcl-XL, play a central role in preventing the induction of apoptosis via the intrinsic apoptotic pathway. It has been previously shown that induction of apoptosis by the pro-apoptotic Bcl-2 family member Bok is not antagonized by either Bcl-2 or BCl-x(L), suggesting that Bok might have a unique role in the apoptotic cascade. We showed here that human Bok is the only member of the Bcl-2 family to have a leucine-rich sequence indicative of a nuclear export signal within its BH3 domain. Western blot analysis of nuclear and cytoplasmic fractions identified Bok in both the nucleus and the cytoplasm of HEK 293T cells, HeLa cells, and breast cancer cells, and its nuclear concentration increased after treatment of those cells with leptomycin 3, an inhibitor of the exportin Crm1. Immunocytochemistry of flag-tagged Bok confirmed its nuclear localization. Mutating the nuclear export signal of Bok by site-directed mutagenesis resulted in an increase in its nuclear localization and apoptotic activity. We also found that Crm1 interacted with wild-type Bok but not with the mutated form. These results suggest that nuclear export of Bok is a regulated process mediated by Crml, and constitutes the first report of a link between the apoptotic activity and nuclear localization of a pro-apoptotic member of the Bc1-2 family. (c) 2005 Wiley-Liss, Inc.