Galkin I I, Pletjushkina O Yu, Zinovkin R A, Zakharova V V, Chernyak B V, Popova E N
Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119991, Russia.
Biochemistry (Mosc). 2016 Oct;81(10):1188-1197. doi: 10.1134/S0006297916100163.
Prolonged or excessive increase in the circulatory level of proinflammatory tumor necrosis factor (TNF) leads to abnormal activation and subsequent damage to endothelium. TNF at high concentrations causes apoptosis of endothelial cells. Previously, using mitochondria-targeted antioxidants of SkQ family, we have shown that apoptosis of endothelial cells is dependent on the production of reactive oxygen species (ROS) in mitochondria (mito-ROS). Now we have found that TNF at low concentrations does not cause cell death but activates caspase-3 and caspase-dependent increase in endothelial permeability in vitro. This effect is probably due to the cleavage of β-catenin - an adherent junction protein localized in the cytoplasm. We have also shown that extracellular matrix metalloprotease 9 (MMP9) VE-cadherin shedding plays a major role in the TNF-induced endothelial permeability. The mechanisms of the caspase-3 and MMP9 activation are probably not related to each other since caspase inhibition did not affect VE-cadherin cleavage and MMP9 inhibition had no effect on the caspase-3 activation. Mitochondria-targeted antioxidant SkQR1 inhibited TNF-induced increase in endothelial permeability. SkQR1 also inhibited caspase-3 activation, β-catenin cleavage, and MMP9-dependent VE-cadherin shedding. The data suggest that mito-ROS are involved in the increase in endothelial permeability due to the activation of both caspase-dependent cleavage of intracellular proteins and of MMP9-dependent cleavage of the transmembrane cell-to-cell contact proteins.
促炎肿瘤坏死因子（TNF）循环水平的长期或过度升高会导致内皮细胞异常激活并随后受损。高浓度的TNF会导致内皮细胞凋亡。此前，我们使用SkQ家族的线粒体靶向抗氧化剂发现，内皮细胞凋亡依赖于线粒体中活性氧（ROS）的产生（线粒体ROS）。现在我们发现，低浓度的TNF不会导致细胞死亡，但会在体外激活caspase-3并导致caspase依赖性的内皮通透性增加。这种效应可能是由于β-连环蛋白（一种位于细胞质中的粘附连接蛋白）的裂解。我们还表明，细胞外基质金属蛋白酶9（MMP9）介导的血管内皮钙黏蛋白脱落在TNF诱导的内皮通透性中起主要作用。caspase-3和MMP9激活的机制可能彼此无关，因为caspase抑制不影响血管内皮钙黏蛋白的裂解，而MMP9抑制对caspase-3激活没有影响。线粒体靶向抗氧化剂SkQR1可抑制TNF诱导的内皮通透性增加。SkQR1还可抑制caspase-3激活、β-连环蛋白裂解以及MMP9依赖性的血管内皮钙黏蛋白脱落。数据表明，线粒体ROS参与了内皮通透性的增加，这是由于细胞内蛋白质的caspase依赖性裂解和跨膜细胞间接触蛋白的MMP9依赖性裂解均被激活。
