Downregulation of free ubiquitin: a novel mechanism of p53 stabilization and neuronal cell death
Downregulation of free ubiquitin: a novel mechanism of p53 stabilization and neuronal cell death
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DOI：
10.1016/s0169-328x(01)00117-6
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发表时间：
2001-07-13
期刊：
影响因子：
--
通讯作者：
Schreiber, SS
中科院分区：
文献类型：
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作者：
Tan, ZQ;Tu, WL;Schreiber, SS
通过激活p53应激反应途径导致的神经元死亡与神经退行性疾病的发病机制有关。调节神经元中p53积累和功能的机制知之甚少。最近的证据表明，Mdm 2是p53的主要抑制剂，其结合并靶向p53以进行泛素介导的降解。在这里，我们证明了增加的表达和共同定位的p53和MDM 2在退化的神经元的细胞核中的兴奋毒素，红藻氨酸，或拓扑异构酶I抑制剂，喜树碱治疗后。免疫共沉淀研究表明，p53-Mdm 2复合物存在于神经元裂解物。双重免疫荧光显微镜表明，这些复合物积累在神经元中的游离泛素水平显着下降。外源性泛素恢复p53降解的提取物从受伤的神经元确认Mdm 2的功能是完整的。最后，在培养的海马神经元中，反义介导的泛素下调导致p53和Mdm 2积累以及凋亡性死亡。这些结果指出了一种新的机制，以稳定p53和促进中枢神经系统中的神经元细胞死亡。(C)2001 Elsevier Science B. V.保留所有权利。
Neuronal death through activation of the p53 stress response pathway has been implicated in the pathogenesis of neurodegenerative disorders. The mechanisms regulating p53 accumulation and function in neurons are poorly understood. Recent evidence has demonstrated that Mdm2 is a major inhibitor of p53 that binds to and targets p53 for ubiquitin-mediated degradation. Here we demonstrate increased expression and co-localization of p53 and Mdm2 in the nuclei of degenerating neurons following treatment with either the excitotoxin, kainic acid, or the topoisomerase I inhibitor, camptothecin. Co-immunoprecipitation studies showed that p53-Mdm2 complexes were present in neuronal lysates. Dual immunofluorescence microscopy demonstrated that these complexes accumulated in neurons with a striking decrease in free ubiquitin levels. Exogenous ubiquitin restored p53 degradation to extracts from injured neurons confirming that Mdm2 function was intact. Finally, antisense-mediated downregulation of ubiquitin in cultured hippocampal neurons resulted in p53 and Mdm2 accumulation as well as apoptotic death. These results point to a novel mechanism to stabilize p53 and promote neuronal cell death in the central nervous system. (C) 2001 Elsevier Science B.V. All rights reserved.