Metere Alessio, Mallozzi Cinzia, Minetti Maurizio, Domenici Maria Rosaria, Pèzzola Antonella, Popoli Patrizia, Di Stasi A M Michela
Department of Cell Biology and Neuroscience, Istituto Superiore di Sanita, Rome, Italy.
J Neurochem. 2006 Jun;97(5):1327-36. doi: 10.1111/j.1471-4159.2006.03814.x. Epub 2006 Apr 21.
Quinolinic acid (QA) has been shown to evoke neurotoxic events via NMDA receptor (NMDAR) overactivation and oxidative stress. NMDARs are particularly vulnerable to free radicals, which can modulate protein tyrosine kinase (PTK) and phosphotyrosine phosphatase (PTP) activities. The src family of tyrosine kinases are associated with the NMDAR complex and regulate NMDA channel function. Because QA is an NMDAR agonist as well as a pro-oxidant agent, we investigated whether it may affect the activity of PTKs and PTPs in vivo and in vitro. In synaptosomes prepared from striata dissected 15 min, 30 min or 15 days after bilateral injection of QA we observed modulation of the phosphotyrosine pattern; a significant decrease in PTP activity; and a sustained increase in c-src and lyn activity at 15 and 30 min after treatment with QA, followed by a decrease 2 weeks later. Striatal synaptosomes treated in vitro with QA showed time- and dose-dependent modulation of c-src and lyn kinase activities. Moreover, the nitric oxide synthase inhibitor NG-nitro-L-arginine-methyl ester, the NMDAR antagonist d-2-amino-5-phosphonovaleric acid and pyruvate suppressed the QA-induced modulation of c-src activity. These findings suggest a novel feature of QA in regulating src kinase activity through the formation of reactive radical species and/or NMDAR overactivation.
喹啉酸（QA）已被证明可通过N-甲基-D-天冬氨酸受体（NMDAR）过度激活和氧化应激引发神经毒性事件。NMDARs对自由基特别敏感，自由基可调节蛋白酪氨酸激酶（PTK）和磷酸酪氨酸磷酸酶（PTP）的活性。酪氨酸激酶的src家族与NMDAR复合物相关，并调节NMDA通道功能。由于QA既是NMDAR激动剂又是促氧化剂，我们研究了它是否可能在体内和体外影响PTKs和PTPs的活性。在双侧注射QA后15分钟、30分钟或15天解剖的纹状体制备的突触体中，我们观察到磷酸酪氨酸模式的调节；PTP活性显著降低；用QA处理后15分钟和30分钟时，c-src和lyn活性持续增加，随后在2周后降低。用QA体外处理的纹状体突触体显示出c-src和lyn激酶活性的时间和剂量依赖性调节。此外，一氧化氮合酶抑制剂NG-硝基-L-精氨酸甲酯、NMDAR拮抗剂D-2-氨基-5-磷酸戊酸和丙酮酸抑制了QA诱导的c-src活性调节。这些发现表明QA通过形成活性自由基和/或NMDAR过度激活来调节src激酶活性具有新的特点。
