Oxidized low-density lipoprotein-activated c-Jun NH2-terminal kinase regulates manganese superoxide dismutase ubiquitination: implication for mitochondrial redox status and apoptosis.
Oxidized low-density lipoprotein-activated c-Jun NH2-terminal kinase regulates manganese superoxide dismutase ubiquitination: implication for mitochondrial redox status and apoptosis.
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DOI：
10.1161/atvbaha.109.202135
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发表时间：
2010-03
期刊：
影响因子：
--
通讯作者：
Hsiai TK
中科院分区：
文献类型：
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作者：
Takabe W;Li R;Ai L;Yu F;Berliner JA;Hsiai TK
氧化低密度脂蛋白 (oxLDL) 调节细胞内氧化还原状态并诱导内皮细胞凋亡。然而，信号通路和分子机制仍不清楚。在本研究中，我们通过 c-Jun NH2 末端激酶 (JNK) 介导的泛素/蛋白酶体途径研究了锰超氧化物歧化酶 (Mn-SOD) 对 oxLDL 诱导的细胞凋亡的作用。 OxLDL 诱导人主动脉内皮细胞中的 JNK 磷酸化在 30 分钟时达到峰值。荧光激活细胞分选分析显示，oxLDL 使线粒体超氧化物产量增加 1.88±0.19 倍，线粒体膜电位增加 18%。 JNK 小干扰 RNA (siJNK) 使 oxLDL 诱导的线粒体超氧化物产生减少 88.4%，线粒体膜电位减少 61.7%。 OxLDL 不影响 Mn-SOD mRNA 表达，但显着降低 Mn-SOD 蛋白水平，siJNK 可以恢复该水平。泛素抗体的免疫沉淀显示，oxLDL 增加了 Mn-SOD 的泛素化，而 siJNK 抑制了 Mn-SOD 的泛素化。 OxLDL 诱导的 caspase-3 活性也被 siJNK 减弱，但被 Mn-SOD 小干扰 RNA 增强。此外，Mn-SOD 的过度表达消除了 oxLDL 诱导的 caspase-3 活性。 OxLDL 诱导的 JNK 激活通过 JNK 依赖性泛素化调节线粒体氧化还原状态和 Mn-SOD 蛋白降解，导致内皮细胞凋亡。
Oxidized low-density lipoprotein (oxLDL) modulates intracellular redox status and induces apoptosis in endothelial cells. However, the signal pathways and molecular mechanism remain unknown. In this study, we investigated the role of manganese superoxide dismutase (Mn-SOD) on oxLDL-induced apoptosis via c-Jun NH2-terminal kinase (JNK)-mediated ubiquitin/proteasome pathway. OxLDL induced JNK phosphorylation that peaked at 30 minutes in human aortic endothelial cells. Fluorescence-activated cell sorting analysis revealed that oxLDL increased mitochondrial superoxide production by 1.88±0.19-fold and mitochondrial membrane potential by 18%. JNK small interference RNA (siJNK) reduced oxLDL-induced mitochondrial superoxide production by 88.4% and mitochondrial membrane potential by 61.7%. OxLDL did not affect Mn-SOD mRNA expression, but it significantly reduced Mn-SOD protein level, which was restored by siJNK. Immunoprecipitation by ubiquitin antibody revealed that oxLDL increased ubiquitination of Mn-SOD, which was inhibited by siJNK. OxLDL-induced caspase-3 activities were also attenuated by siJNK but were enhanced by Mn-SOD small interfering RNA. Furthermore, overexpression of Mn-SOD abrogated oxLDL-induced caspase-3 activities. OxLDL-induced JNK activation regulates mitochondrial redox status and Mn-SOD protein degradation via JNK-dependent ubiquitination, leading to endothelial cell apoptosis.