DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milano, Italy.
DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133, Milano, Italy; Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania, Luigi Vanvitelli, Caserta, Italy.
Neurobiol Dis. 2017 Dec;108:54-64. doi: 10.1016/j.nbd.2017.08.001. Epub 2017 Aug 18.
N-methyl-d-aspartate receptor (NMDAR) subunit composition strictly commands receptor function and pharmacological responses. Changes in NMDAR subunit composition have been documented in brain disorders such as Parkinson's disease (PD) and levodopa (L-DOPA)-induced dyskinesias (LIDs), where an increase of NMDAR GluN2A/GluN2B subunit ratio at striatal synapses has been observed. A therapeutic approach aimed at rebalancing NMDAR synaptic composition represents a valuable strategy for PD and LIDs. To this, the comprehension of the molecular mechanisms regulating the synaptic localization of different NMDAR subtypes is required. We have recently demonstrated that Rabphilin 3A (Rph3A) is a new binding partner of NMDARs containing the GluN2A subunit and that it plays a crucial function in the synaptic stabilization of these receptors. Considering that protein-protein interactions govern the synaptic retention of NMDARs, the purpose of this work was to analyse the role of Rph3A and Rph3A/NMDAR complex in PD and LIDs, and to modulate Rph3A/GluN2A interaction to counteract the aberrant motor behaviour associated to chronic L-DOPA administration. Thus, an array of biochemical, immunohistochemical and pharmacological tools together with electron microscopy were applied in this study. Here we found that Rph3A is localized at the striatal postsynaptic density where it interacts with GluN2A. Notably, Rph3A expression at the synapse and its interaction with GluN2A-containing NMDARs were increased in parkinsonian rats displaying a dyskinetic profile. Acute treatment of dyskinetic animals with a cell-permeable peptide able to interfere with Rph3A/GluN2A binding significantly reduced their abnormal motor behaviour. Altogether, our findings indicate that Rph3A activity is linked to the aberrant synaptic localization of GluN2A-expressing NMDARs characterizing LIDs. Thus, we suggest that Rph3A/GluN2A complex could represent an innovative therapeutic target for those pathological conditions where NMDAR composition is significantly altered.
N-甲基-D-天冬氨酸受体 (NMDAR) 亚基组成严格控制受体功能和药理反应。在帕金森病 (PD) 和左旋多巴 (L-DOPA) 诱导的运动障碍 (LIDs) 等脑部疾病中，已经记录到 NMDAR 亚基组成的变化，其中观察到纹状体突触处 NMDAR GluN2A/GluN2B 亚基比率增加。旨在重新平衡 NMDAR 突触组成的治疗方法代表了 PD 和 LIDs 的一种有价值的策略。为此，需要了解调节不同 NMDAR 亚型突触定位的分子机制。我们最近证明 Rabphilin 3A (Rph3A) 是含有 GluN2A 亚基的 NMDAR 的新结合伴侣，并且它在这些受体的突触稳定化中发挥关键作用。考虑到蛋白质-蛋白质相互作用控制 NMDAR 的突触保留，这项工作的目的是分析 Rph3A 和 Rph3A/NMDAR 复合物在 PD 和 LIDs 中的作用，并调节 Rph3A/GluN2A 相互作用以对抗与慢性 L-DOPA 给药相关的异常运动行为。因此，本研究应用了一系列生化、免疫组织化学和药理学工具以及电子显微镜。在这里，我们发现 Rph3A 定位于纹状体突触后密度处，在那里它与 GluN2A 相互作用。值得注意的是，在表现出运动障碍特征的帕金森病大鼠中，突触处的 Rph3A 表达及其与含有 GluN2A 的 NMDAR 的相互作用增加。急性用一种可渗透细胞的肽处理运动障碍动物，该肽能够干扰 Rph3A/GluN2A 结合，显著降低了它们的异常运动行为。总的来说，我们的研究结果表明，Rph3A 活性与 LIDs 中特征性的 GluN2A 表达的 NMDAR 的异常突触定位有关。因此，我们认为 Rph3A/GluN2A 复合物可能代表那些 NMDAR 组成发生显著改变的病理状况的创新治疗靶点。
