Mitochondrial permeabilization without caspase activation mediates the increase of basal apoptosis in cells lacking Nrf2.
Mitochondrial permeabilization without caspase activation mediates the increase of basal apoptosis in cells lacking Nrf2.
复制标题
没有 caspase 激活的线粒体通透介导缺乏 Nrf2 的细胞基础细胞凋亡的增加。
DOI：
10.1016/j.freeradbiomed.2016.03.015
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发表时间：
2016-06
影响因子：
7.4
通讯作者：
Villalba JM
中科院分区：
文献类型：
--
作者：
Ariza J;González-Reyes JA;Jódar L;Díaz-Ruiz A;de Cabo R;Villalba JM
核因子E2相关因子2（Nuclear factor E2-related factor-2，Nrf 2）是一种具有帽环/碱性亮氨酸拉链（cap 'n'collar/basic leucine zipper，b-ZIP）结构的转录因子，可作为氧化和亲电应激的传感器。低水平的Nrf 2使细胞易于发生化学致癌作用，但Nrf 2功能的黑暗面也存在，因为其无限制的激活可能使潜在危险的受损细胞存活。由于Nrf 2抑制可能在癌症中具有治疗意义，并且Nrf 2活性的降低可能与衰老相关的退行性变化有关，因此研究Nrf 2功能的缺乏如何激活介导细胞死亡的分子机制非常重要。与野生型小鼠胚胎成纤维细胞（MEF）相比，携带Nrf 2缺失（Nrf 2KO）的小鼠胚胎成纤维细胞（MEF）显示出细胞生长速率降低和寿命缩短。DNA断裂和组蛋白H2A.X磷酸化的基础速率在Nrf 2KO MEFs中较高，尽管活性氧的稳态水平没有显著增加。在Nrf 2KO小鼠的肝和肺组织中证实了凋亡DNA片段化的增强速率。Nrf 2KO MEFs中的细胞凋亡与Bcl-2而不是Bax水平的降低相关，并且与线粒体促凋亡因子细胞色素c和AIF的释放相关。在Nrf 2 KO MEFs中，半胱天冬酶-9和Apaf-1也增加，但半胱天冬酶-3未活化。抑制XIAP增加了Nrf 2KO中的死亡，但在野生型MEF中没有。线粒体超微结构也发生了改变。我们的研究结果支持Nrf 2缺失产生与线粒体透化相关的线粒体功能障碍，通过半胱天冬酶非依赖性和AIF依赖性途径增加基础凋亡。
Nuclear factor E2-related factor-2 (Nrf2) is a cap’n’collar/basic leucine zipper (b-ZIP) transcription factor which acts as sensor of oxidative and electrophilic stress. Low levels of Nrf2 predispose cells to chemical carcinogenesis but a dark side of Nrf2 function also exists because its unrestrained activation may allow the survival of potentially dangerous damaged cells. Since Nrf2 inhibition may be of therapeutic interest in cancer, and a decrease of Nrf2 activity may be related with degenerative changes associated with aging, it is important to investigate how the lack of Nrf2 function activates molecular mechanisms mediating cell death. Murine Embryonic Fibroblasts (MEFs) bearing a Nrf2 deletion (Nrf2KO) displayed diminished cellular growth rate and shortened lifespan compared with wild-type MEFs. Basal rates of DNA fragmentation and histone H2A.X phosphorylation were higher in Nrf2KO MEFs, although steady-state levels of reactive oxygen species were not significantly increased. Enhanced rates of apoptotic DNA fragmentation were confirmed in liver and lung tissues from Nrf2KO mice. Apoptosis in Nrf2KO MEFs was associated with a decrease of Bcl-2 but not Bax levels, and with the release of the mitochondrial pro-apoptotic factors cytochrome c and AIF. Procaspase-9 and Apaf-1 were also increased in Nrf2KO MEFs but caspase-3 was not activated. Inhibition of XIAP increased death in Nrf2KO but not in wild-type MEFs. Mitochondrial ultrastructure was also altered in Nrf2KO MEFs. Our results support that Nrf2 deletion produces mitochondrial dysfunction associated with mitochondrial permeabilization, increasing basal apoptosis through a caspase-independent and AIF-dependent pathway.