DRP-1 functions independently of mitochondrial structural perturbations to facilitate BH3 mimetic-mediated apoptosis
DRP-1 functions independently of mitochondrial structural perturbations to facilitate BH3 mimetic-mediated apoptosis
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DOI：
10.1038/s41420-019-0199-x
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发表时间：
2019-07-17
影响因子：
7
通讯作者：
Varadarajan, Shankar
中科院分区：
文献类型：
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作者：
Milani, Mateus;Beckett, Alison J.;Varadarajan, Shankar
线粒体完整性的维持对于正常的细胞内稳态是至关重要的。大多数细胞响应于应激刺激并通过扰乱线粒体结构和功能以释放蛋白质（如细胞色素c）而经历凋亡，所述蛋白质对于执行内在凋亡级联是必不可少的。癌细胞通过在线粒体膜上过表达抗凋亡BCL-2蛋白家族来逃避这些事件。抗凋亡BCL-2家族蛋白的抑制剂，也称为BH 3模拟物，拮抗这些蛋白的促存活功能并导致快速凋亡。虽然BH 3模拟物诱导细胞凋亡的确切机制已被很好地表征，但在细胞凋亡期间线粒体中发生的结构变化方面知之甚少。使用一组高选择性的BH 3模拟物和广泛的细胞系，我们证明BH 3模拟物诱导广泛的线粒体分裂，伴随着线粒体基质的肿胀和线粒体外膜的破裂。这些变化以BAX/BAK依赖的方式发生。虽然一个主要的线粒体分裂GTP酶，DRP-1，已经牵连在线粒体凋亡，我们的数据表明，DRP-1可能独立/下游的BH 3模拟介导的线粒体分裂，以促进细胞色素c的释放和细胞凋亡。此外，下调DRP-1阻止细胞色素c的释放和细胞凋亡，即使当OPA 1，介导线粒体融合的蛋白质，沉默。尽管BH 3模拟物介导的巴克和其他仅BH 3蛋白从BCL-XL和MCL-1的置换不受DRP-1下调的影响，但它显著阻止了巴克活化，因此将DRP-1作为最关键的参与者之一，沿着BAX和巴克，其控制BH 3模拟物介导的细胞色素c释放和细胞凋亡。
Maintenance of mitochondrial integrity is critical for normal cellular homoeostasis. Most cells respond to stress stimuli and undergo apoptosis by perturbing mitochondrial structure and function to release proteins, such as cytochrome c, which are essential for the execution of the intrinsic apoptotic cascade. Cancer cells evade these events by overexpressing the anti-apoptotic BCL-2 family of proteins on mitochondrial membranes. Inhibitors of the antiapoptotic BCL-2 family proteins, also known as BH3 mimetics, antagonise the pro-survival functions of these proteins and result in rapid apoptosis. Although the precise mechanism by which BH3 mimetics induce apoptosis has been well characterised, not much is known in terms of the structural changes that occur in mitochondria during apoptosis. Using a panel of highly selective BH3 mimetics and a wide range of cell lines, we demonstrate that BH3 mimetics induce extensive mitochondrial fission, accompanied by swelling of the mitochondrial matrix and rupture of the outer mitochondrial membrane. These changes occur in a BAX/BAK-dependent manner. Although a major mitochondrial fission GTPase, DRP-1, has been implicated in mitochondrial apoptosis, our data demonstrate that DRP-1 might function independently/downstream of BH3 mimetic-mediated mitochondrial fission to facilitate the release of cytochrome c and apoptosis. Moreover, downregulation of DRP-1 prevented cytochrome c release and apoptosis even when OPA1, a protein mediating mitochondrial fusion, was silenced. Although BH3 mimetic-mediated displacement of BAK and other BH3-only proteins from BCL-XL and MCL-1 was unaffected by DRP-1 downregulation, it prevented BAK activation significantly, thus placing DRP-1 as one of the most critical players, along with BAX and BAK, that governs BH3 mimetic-mediated cytochrome c release and apoptosis.