Dual autonomous mitochondrial cell death pathways are activated by Nix/BNip3L and induce cardiomyopathy
Dual autonomous mitochondrial cell death pathways are activated by Nix/BNip3L and induce cardiomyopathy
复制标题
DOI：
10.1073/pnas.0914013107
复制
发表时间：
2010-05-18
影响因子：
11.1
通讯作者：
Dorn, Gerald W., II
中科院分区：
文献类型：
--
作者：
Chen, Yun;Lewis, William;Dorn, Gerald W., II
由于Bcl-2蛋白的异常表达引起的程序性细胞死亡的失调与癌症、神经退行性疾病和心力衰竭有关。在Bcl-2家族成员中，BNip蛋白独特地刺激具有凋亡和坏死特征的细胞死亡。这些因子定位于线粒体和内质网（ER）提供了额外的复杂性。在此之前，我们观察到网状Nix对细胞内钙储备的调节。在这里，我们报告了Nix靶向线粒体或ER对细胞死亡途径和心力衰竭进展的影响。Nix缺陷的成纤维细胞表达的Nix突变体的细胞色素C释放，半胱天冬酶激活，膜联蛋白V和TUNEL标记，和细胞死亡表现出相似的。ER-Nix细胞，而非Ekal-Nix细胞，显示线粒体内膜电位Δ psi（m）的耗散，并且通过环孢菌素A或ppif消融而免于细胞死亡，这涉及线粒体渗透性转换孔（MPTP）。ER-Nix细胞不能通过半胱天冬酶抑制或Bax和巴克的联合消融而免于死亡。半胱天冬酶和MPTP的组合抑制完全防止了Nix介导的细胞死亡。为了确定双重途径在心力衰竭中的作用，建立了心脏中条件性过表达Nix或Nix突变体的小鼠。经皮和ER定向Nix引起的心肌细胞死亡是等效的，但ppif消融完全保护了ER Nix。因此，Nix刺激双自主死亡途径，由其亚细胞定位决定。线粒体Nix激活Bax/巴克-和半胱天冬酶-依赖性凋亡，而ER-Nix激活Bax/巴克-非依赖性，MPTP-依赖性坏死。通过同时抑制这两种途径，可以实现对Nix和相关因子介导的程序性细胞死亡的完全保护。
Dysregulation of programmed cell death due to abnormal expression of Bcl-2 proteins is implicated in cancer, neurodegenerative diseases, and heart failure. Among Bcl-2 family members, BNip proteins uniquely stimulate cell death with features of both apoptosis and necrosis. Localization of these factors to mitochondria and endoplasmic reticulum (ER) provides additional complexity. Previously, we observed regulation of intracellular calcium stores by reticular Nix. Here, we report effects of Nix targeting to mitochondria or ER on cell death pathways and heart failure progression. Nix-deficient fibroblasts expressing mitochondrial-directed or ER-directed Nix mutants exhibited similar cytochrome c release, caspase activation, annexin V and TUNEL labeling, and cell death. ER-Nix cells, but not mitochondrial-Nix cells, showed dissipation of mitochondrial inner membrane potential Delta psi(m), and were protected from cell death by cyclosporine A or ppif ablation, implicating the mitochondrial permeability transition pore (MPTP). ER-Nix cells were not protected from death by caspase inhibition or combined ablation of Bax and Bak. Combined inhibition of caspases and the MPTP fully protected against Nix-mediated cell death. To determine the role of the dual pathways in heart failure, mice conditionally overexpressing Nix or Nix mutants in hearts were created. Cardiomyocte death caused by mitochondrial-and ER-directed Nix was equivalent, but ppif ablation fully protected only ER-Nix. Thus, Nix stimulates dual autonomous death pathways, determined by its subcellular localization. Mitochondrial Nix activates Bax/Bak- and caspase-dependent apoptosis, whereas ER-Nix activates Bax/Bak-independent, MPTP-dependent necrosis. Complete protection against programmed cell death mediated by Nix and related factors can be achieved by simultaneous inhibition of both pathways.