Department of Pharmacology and Laboratory of Aging and Nervous Diseases (SZS0703), Soochow University School of Medicine, Suzhou, China.
Eur J Neurosci. 2009 Dec;30(12):2258-70. doi: 10.1111/j.1460-9568.2009.07025.x. Epub 2009 Dec 10.
The present study sought to investigate mechanisms by which p53 induction contributes to excitotoxic neuronal injury. Rats were intrastriatally administered the N-methyl-D-aspartate (NMDA) receptor agonist quinolinic acid (QA), the changes in the expression of p53 and its target genes involved in apoptosis and autophagy, including p53-upregulated modulator of apoptosis (PUMA), Bax, Bcl-2, damage-regulated autophagy modulator (DRAM) and other autophagic proteins including microtubule-associated protein 1 light chain 3 (LC3) and beclin 1 were assessed. The contribution of p53-mediated autophagy activation to apoptotic death of striatal neurons was assessed with co-administration of the nuclear factor-kappaB (NF-kappaB) inhibitor SN50, the p53 inhibitor Pifithrin-alpha (PFT-alpha) or the autophagy inhibitor 3-methyladenine (3-MA). The increased formation of autophagosomes and secondary lysosomes were observed with transmission electron microscope after excitotoxin exposure. QA induced increases in the expression of p53, PUMA, Bax and a decrease in Bcl-2. These changes were significantly attenuated by pre-treatment with SN50, PFT-alpha or 3-MA. SN50, PFT-alpha or 3-MA also reversed QA-induced upregulation of DRAM, the ratio of LC3-II/LC3-I and beclin 1 protein levels in the striatum. QA-induced internucleosomal DNA fragmentation and loss of striatal neurons were robustly inhibited by SN50, PFT-alpha or 3-MA. These results suggest that overstimulation of NMDA receptors can induce NF-kappaB-dependent expression of p53. p53 participates in excitotoxic neuronal death probably through both apoptotic and autophagic mechanisms.
本研究旨在探讨 p53 诱导在兴奋性神经元损伤中的作用机制。通过向纹状体中给予 N-甲基-D-天冬氨酸（NMDA）受体激动剂喹啉酸（QA），评估了 p53 及其参与凋亡和自噬的靶基因（包括 p53 上调凋亡调节剂（PUMA）、Bax、Bcl-2、损伤调节自噬调节剂（DRAM）和其他自噬蛋白，如微管相关蛋白 1 轻链 3（LC3）和 Beclin 1）的表达变化。通过共同给予核因子-κB（NF-κB）抑制剂 SN50、p53 抑制剂 Pifithrin-alpha（PFT-alpha）或自噬抑制剂 3-甲基腺嘌呤（3-MA），评估了 p53 介导的自噬激活对纹状体神经元凋亡死亡的贡献。在兴奋性毒素暴露后，用透射电子显微镜观察到自噬体和次级溶酶体的形成增加。QA 诱导 p53、PUMA、Bax 的表达增加，Bcl-2 的表达减少。这些变化被 SN50、PFT-alpha 或 3-MA 的预处理显著减弱。SN50、PFT-alpha 或 3-MA 还逆转了 QA 诱导的 DRAM、LC3-II/LC3-I 比值和 Beclin 1 蛋白水平的上调。SN50、PFT-alpha 或 3-MA 还强烈抑制了 QA 诱导的核小体间 DNA 片段化和纹状体神经元的丢失。这些结果表明，NMDA 受体的过度刺激可诱导 NF-κB 依赖性 p53 表达。p53 可能通过凋亡和自噬机制参与兴奋性神经元死亡。
