Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198-5870.
Eppley Institute for Research in Cancer and Allied Diseases, The Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-5870.
Mol Biol Cell. 2019 May 1;30(10):1138-1146. doi: 10.1091/mbc.E19-01-0044. Epub 2019 Mar 6.
The anti-apoptotic Bcl-2 family protein Bcl-xL plays a critical role in cell survival by protecting the integrity of the mitochondrial outer membrane (MOM). The mechanism through which Bcl-xL is recruited to the MOM has not been fully discerned. The retromer is a conserved endosomal scaffold complex involved in membrane trafficking. Here we identify VPS35 and VPS26, two core components of the retromer, as novel regulators of Bcl-xL. We observed interactions and colocalization between Bcl-xL, VPS35, VPS26, and MICAL-L1, a protein involved in recycling endosome biogenesis that also interacts with the retromer. We also found that upon VPS35 depletion, levels of nonmitochondrial Bcl-xL were increased. In addition, retromer-depleted cells displayed more rapid Bax activation and apoptosis. These results suggest that the retromer regulates apoptosis by facilitating Bcl-xL's transport to the MOM. Importantly, our studies suggest a previously uncharacterized relationship between the machineries of cell death/survival and endosomal trafficking.
抗凋亡 Bcl-2 家族蛋白 Bcl-xL 通过保护线粒体外膜（MOM）的完整性在细胞存活中发挥关键作用。Bcl-xL 被招募到 MOM 的机制尚未完全阐明。Retromer 是一种保守的内体支架复合物，参与膜运输。在这里，我们确定了 VPS35 和 VPS26，Retromer 的两个核心组件，是 Bcl-xL 的新型调节因子。我们观察到 Bcl-xL、VPS35、VPS26 和 MICAL-L1 之间的相互作用和共定位，MICAL-L1 是一种参与再循环内体生物发生的蛋白质，也与 retromer 相互作用。我们还发现，在 VPS35 耗尽后，非线粒体 Bcl-xL 的水平增加。此外，Retromer 耗尽的细胞显示出更快的 Bax 激活和凋亡。这些结果表明，Retromer 通过促进 Bcl-xL 向 MOM 的转运来调节细胞凋亡。重要的是，我们的研究表明细胞死亡/存活机制和内体运输之间存在以前未表征的关系。
