MODULATION OF D2-LIKE DOPAMINE RECEPTOR-MEDIATED STRIATAL SIGNALING PATHWAYS BY

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 这个子项目将研究纹状体特异蛋白RGS9-2的功能，RGS9-2是G？GTP酶加速蛋白RGS家族的成员。我们以前的数据表明，RGS9-2在L-多巴诱导的运动障碍(LID)和迟发性运动障碍(TD)的发生发展中起关键作用。LID和TD分别是帕金森病和精神障碍药物治疗的不可逆转的神经运动毒性。虽然病因尚不清楚，但我们提出了一个初步的分子模型：D2-多巴胺受体(D2DR)是抗精神病药物和L多巴的主要靶点。RGS9-2通过RGS9 DEP结构域靶向D2DR，并在功能上区分纹状体神经元中的D2DR，以阻断D2DR介导的对NMDA受体和钙通道的抑制。长期的药物治疗会产生代偿性改变，破坏RGS9-2介导的细胞区隔。这些代偿反应导致基底节信号处理异常和药物引起的异常不自主运动。要确定这种区划是如何被破坏的，需要更好地理解D2DR-RGS9-2相互作用，这是我们的共定位研究所提出的。因此，我们将确定RGS9-2靶向D2DR是否涉及直接或间接的物理相互作用。我们将绘制和表征相互作用的表面，并评估共价修饰(如蛋白质磷酸化)对分子相互作用的影响。此外，我们还将研究在缺乏RGS9的情况下，D2样DR和NMDA受体之间异常信号的分子机制。我们将验证共表达的RGS9-2可以抑制体外重组的D2DR-NMDA-受体偶联的假设。平行方法将研究RGS9-2在纹状体D2DR和电压激活的钙通道之间的耦合中的作用。虽然目前的提案仅限于描述RGS9-2的细胞功能，但我希望这项努力将为我们提供工具，在后续研究中测试、验证和扩展我们初步的LID和TD模型。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This subproject will investigate the functions of a striatal specific protein, RGS9-2, a member of the RGS family of G¿ GTPase accelerating proteins. Our previous data suggest that RGS9-2 is critical in the development of L-DOPA induced dyskinesia (LID) and tardive dyskinesia (TD). LID and TD are irreversible neurological motor toxicities of the pharmacotherapy of Parkinson's disease and psychotic disorders, respectively. While the etiology is unknown we have proposed a prelimainary molecular model: D2-dopamine receptors (D2DR) are a major target of both antipsychotic drugs and L-DOPA. RGS9-2 targets to D2DR via the RGS9 DEP domain and functionally compartmentalizes D2DR in striatal neurons to block D2DR-mediated inhibition of NMDA receptors and Ca2+ channels. Prolonged drug-treatment produces compensatory alterations that disrupt RGS9-2mediated cellular compartmentalization. These compensatory responses, lead to abnormal basal ganglia signal processing and to drug-induced abnormal involuntary movements. Determining how such compartmentalization is disrupted will require a better understanding of the D2DR-RGS9-2 interaction which has been suggested by our colocalization studies. Hence we will determine if the targeting of RGS9-2 to D2DR involves either a direct or indirect physical interaction. We will map and characterize the interacting surfaces and evaluate the effect of covalent modifications such as protein phosphorylation on the molecular interaction. We will in addition investigate the molecular mechanism for abnormal signaling between D2-like DR and NMDA-receptors observed in the absence of RGS9. We will test the hypothesis that coexpressed RGS9-2 can inhibit D2DR-NMDA-receptor coupling reconstituted in vitro. Parallel approaches will examine the role for RGS9-2 in the coupling between striatal D2DR and voltage-activated Ca2+ channels. Though the present proposal is restricted characterizing the cellular function of RGS9-2 it is my expectation that the effort will provide us with the tools to test, validate and expand our preliminary model for LID and TD, in subsequent studies.