The C-terminal transmembrane domain of Bcl-xL mediates changes in mitochondrial morphology.
The C-terminal transmembrane domain of Bcl-xL mediates changes in mitochondrial morphology.
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DOI：
10.1529/biophysj.107.104323
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发表时间：
2008
影响因子：
3.4
通讯作者：
Jing-Yi Zheng;Y. Tsai;P. Kadimcherla;Rong Zhang;J. Shi;G. Oyler;N. Boustany
中科院分区：
文献类型：
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作者：
Jing-Yi Zheng;Y. Tsai;P. Kadimcherla;Rong Zhang;J. Shi;G. Oyler;N. Boustany
我们研究了线粒体定位和 Bcl-x(L) C 端跨膜 (TM) 结构域对线粒体形态和亚细胞光散射的影响。 CSM 14.1 细胞系稳定表达黄色荧光蛋白 (YFP)、YFP-Bcl-x(L,) YFP-Bcl-x(L)-DeltaTM，在删除对应于 TM 结构域的最后 21 个氨基酸后含有 Bcl-x(L) 的剩余部分，或 YFP-TM，由在其 C 端与 Bcl-x(L) 的最后 21 个氨基酸融合的 YFP 组成。 YFP-Bcl-x(L) 和 YFP-TM 定位于线粒体。它们的表达降低了亚细胞细胞器的宽角与窄角前向散射的强度比，并且与电子显微镜观察到的具有扩张基质的线粒体比例的增加相关，该扩张基质大大减少了晶内空间。表达 YFP-TM 的细胞也表现出显着的自噬。相比之下，YFP-Bcl-x(L)-DeltaTM在细胞中广泛分布，与亲本细胞相比，其表达没有改变光散射或线粒体形态。 YFP-Bcl-x(L) 或 YFP-Bcl-x(L)-DeltaTM 的表达对十字孢菌素诱导的细胞凋亡具有显着的抵抗作用。然而令人惊讶的是，YFP-TM 表达还赋予对星形孢菌素的中等水平的细胞死亡抗性。综上所述，我们的结果表明存在由跨膜结构域介导的次级 Bcl-x(L) 功能，改变线粒体形态，并且与 BH3 结构域隔离不同。
We investigate the effect of mitochondrial localization and the Bcl-x(L) C-terminal transmembrane (TM) domain on mitochondrial morphology and subcellular light scattering. CSM 14.1 cell lines stably expressed yellow fluorescent protein (YFP), YFP-Bcl-x(L,) YFP-Bcl-x(L)-DeltaTM, containing the remainder of Bcl-x(L) after deletion of the last 21 amino acids corresponding to the TM domain, or YFP-TM, consisting of YFP fused at its C-terminal to the last 21 amino acids of Bcl-x(L). YFP-Bcl-x(L) and YFP-TM localized to the mitochondria. Their expression decreased the intensity ratio of wide-to-narrow angle forward scatter by subcellular organelles, and correlated with an increase in the proportion of mitochondria with an expanded matrix having greatly reduced intracristal spaces as observed by electron microscopy. Cells expressing YFP-TM also exhibited significant autophagy. In contrast, YFP-Bcl-x(L)-DeltaTM was diffusely distributed in the cells, and its expression did not alter light scattering or mitochondrial morphology compared with parental cells. Expression of YFP-Bcl-x(L) or YFP-Bcl-x(L)-DeltaTM provided significant resistance to staurosporine-induced apoptosis. Surprisingly however, YFP-TM expression also conferred a moderate level of cell death resistance in response to staurosporine. Taken together, our results suggest the existence of a secondary Bcl-x(L) function that is mediated by the transmembrane domain, alters mitochondrial morphology, and is distinct from BH3 domain sequestration.