Movement of Bax from the cytosol to mitochondria during apoptosis.
Movement of Bax from the cytosol to mitochondria during apoptosis.
复制标题
凋亡过程中Bax从细胞质到线粒体的运动。
DOI：
10.1083/jcb.139.5.1281
复制
发表时间：
1997-12-01
期刊：
影响因子：
--
通讯作者：
Youle RJ
中科院分区：
文献类型：
--
作者：
Wolter KG;Hsu YT;Smith CL;Nechushtan A;Xi XG;Youle RJ
Bax是Bcl2蛋白家族中的一员，通过一种未知的机制加速细胞凋亡。Bax是细胞器内的一种完整的膜蛋白，与细胞器结合或与细胞器结合，也可能是胞浆中的一种可溶性蛋白。为了探讨Bcl2家族成员在活细胞中的定位，将绿色荧光蛋白(GFP)融合到Bax、Bcl2和Bclxl的NH2末端。对活的Cos-7肾上皮细胞和L929成纤维细胞进行共聚焦显微镜观察，发现GFP-Bcl2和GFP-Bclxl呈点状分布，并与线粒体标记物共定位，而GFP-Bax弥漫分布于胞浆中。光漂白分析证实GFP-Bax是一种可溶性蛋白，而不是细胞器结合的GFP-Bcl2。GFP-Bax的弥漫性定位与高水平的Bcl2和Bclxl共表达无明显变化。然而，在诱导细胞凋亡时，GFP-Bax在细胞内移动到与线粒体部分共存的点状分布。一旦启动，这种Bax运动在30分钟内完成，之后细胞收缩或核凝聚。从GFP-Bax中去除COOH-末端疏水结构域可抑制细胞在凋亡过程中的再分布，并抑制Bax和GFP-Bax的促死亡活性。这些结果表明，在细胞凋亡过程中，Bax在细胞内的定位发生了早期的、戏剧性的变化，这种可溶性Bax重新分布到细胞器似乎对Bax促进细胞死亡具有重要意义。
Bax, a member of the Bcl-2 protein family, accelerates apoptosis by an unknown mechanism. Bax has been recently reported to be an integral membrane protein associated with organelles or bound to organelles by Bcl-2 or a soluble protein found in the cytosol. To explore Bcl-2 family member localization in living cells, the green fluorescent protein (GFP) was fused to the NH2 termini of Bax, Bcl-2, and Bcl-XL. Confocal microscopy performed on living Cos-7 kidney epithelial cells and L929 fibroblasts revealed that GFP–Bcl-2 and GFP–Bcl-XL had a punctate distribution and colocalized with a mitochondrial marker, whereas GFP–Bax was found diffusely throughout the cytosol. Photobleaching analysis confirmed that GFP–Bax is a soluble protein, in contrast to organelle-bound GFP–Bcl-2. The diffuse localization of GFP–Bax did not change with coexpression of high levels of Bcl-2 or Bcl-XL. However, upon induction of apoptosis, GFP–Bax moved intracellularly to a punctate distribution that partially colocalized with mitochondria. Once initiated, this Bax movement was complete within 30 min, before cellular shrinkage or nuclear condensation. Removal of a COOH-terminal hydrophobic domain from GFP–Bax inhibited redistribution during apoptosis and inhibited the death-promoting activity of both Bax and GFP– Bax. These results demonstrate that in cells undergoing apoptosis, an early, dramatic change occurs in the intracellular localization of Bax, and this redistribution of soluble Bax to organelles appears important for Bax to promote cell death.