Zhang Xiaosha, Bian Xiuwu, Kong Jiming
Institute of Pathology and Southwest Cancer Center, The Third Military Medical University, Chongqing, China; Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada.
Institute of Pathology and Southwest Cancer Center, The Third Military Medical University, Chongqing, China.
PLoS One. 2014 Dec 1;9(12):e113642. doi: 10.1371/journal.pone.0113642. eCollection 2014.
BNIP3 is a proapoptotic protein that induces cell death through a mitochondria-mediated pathway. We reported previously that mitochondrial localization of BNIP3 and translocation of EndoG from mitochondria to the nucleus are critical steps of the BNIP3 pathway. It is not clear, however, that how BNIP3 interacts with mitochondria. Here we show that expression of BNIP3 resulted in mitochondrial release and nuclear translocation of EndoG. Incubation of a recombinant GST-BNIP3 protein with freshly isolated mitochondria led to the integration of BNIP3 into mitochondria, reduction in the levels of EndoG in mitochondria and the presence of EndoG in the supernatant that was able to cleave chromatin DNA. Co-immunoprecipitation and mass spectrometry analysis reveals that BNIP3 interacted with the voltage-dependent anion channel (VDAC) to increase opening probabilities of mitochondrial permeability transition (PT) pores and induce mitochondrial release of EndoG. Blocking VDAC with a VDAC antibody largely abolished mitochondrial localization of BNIP3 and prevented EndoG release. Together, the data identify VDAC as an interacting partner of BNIP3 and support endonuclease G as a mediator of the BNIP3 pathway.
BNIP3是一种促凋亡蛋白，通过线粒体介导的途径诱导细胞死亡。我们之前报道过，BNIP3的线粒体定位以及EndoG从线粒体向细胞核的转位是BNIP3途径的关键步骤。然而，目前尚不清楚BNIP3如何与线粒体相互作用。在此我们表明，BNIP3的表达导致EndoG从线粒体释放并向细胞核转位。将重组GST-BNIP3蛋白与新鲜分离的线粒体一起孵育，导致BNIP3整合到线粒体中，线粒体中EndoG水平降低，而上清液中出现能够切割染色质DNA的EndoG。免疫共沉淀和质谱分析表明，BNIP3与电压依赖性阴离子通道（VDAC）相互作用，增加线粒体通透性转换（PT）孔的开放概率，并诱导EndoG从线粒体释放。用VDAC抗体阻断VDAC可大大消除BNIP3的线粒体定位并阻止EndoG释放。总之，这些数据确定VDAC是BNIP3的相互作用伴侣，并支持核酸内切酶G作为BNIP3途径的介质。
