Project 2

项目总结 多巴胺是一种神经递质，与多种神经和精神疾病有关。中枢神经系统。DA对靶神经元的各种作用是通过典型的7-跨膜G蛋白偶联受体(GPCR)介导的，它与各种效应系统偶联，治疗药物，包括所有临床有效的抗精神病药物，与DA D2受体(D2R)相互作用，引起有益和有害的副作用。在以前的工作中，我们已经证明了纹状体中棘神经(MSN)上的D2Rs通过G蛋白依赖和独立的机制来调节它们的一些活动。这些G蛋白不依赖的作用是通过与AKT/GSKs信号通路的组成部分形成依赖于B-arrestin2的信号复合体来实现的。在我们之前的U-19 NCDD拨款期间的工作已经发现了基于抗真菌药物阿立哌唑的新型小分子，阿立哌唑可以作为Db2R的FUNGTIONALLY选择性配体。这些D2R是G蛋白介导的抑制cAMP产生的激动剂，也是D2R/B-arrestin2相互作用的拮抗剂，反之亦然。此外，利用药理学或高多巴胺能功能的遗传小鼠rnodels，选择性D2R/B抑制蛋白2相互作用的化合物显示出有效的抗精神病活性，而没有相关的过敏性副作用。相比之下，这些化合物在缺乏B2R/p-arrestih2相互作用的B2R/p-arrestih2基因敲除小鼠中引起了显著的副作用。这些结果表明，D2R；/B-arrestin2信号可能对这些有害的影响具有保护作用。在项目2中，我们将使用细胞和脑区域选择性失活或挽救D2R信号通路的组件来验证我们的初步结果，并确定导致新发现的功能性选择性D2R配体的抗精神病药物特征(S)的细胞和分子事件。目的1：我们将通过使用B-arrestin2和GSK3B选择性失活的小鼠来验证D2R/抗精神病作用的新小鼠模型；目标2：我们将描述内源性D2R已被野生型B2R或能够选择性偶联G蛋白或p-arrestin2信号的突变D2R所替代的小鼠的新配体。目的3：我们将通过在不同动物模型中检测与这些药物的有益/副作用作用相关的生化、生理和细胞事件来确定这些新型抗精神病药物的细胞和分子图谱。我们预计这些努力将导致以下概念的验证：靶向D2R/B-arrestin2信号转导将为临床研究开发更具选择性和有效的治疗药物提供新的配体。

PROJECT SUMMARY Dopamine is a, neurotransmitter that has been implicated in multiple neurological and psychiatric disorders in the. CNS. The various actions of DA on target neurons are mediated via prototypical 7-transmembrane G protein-Coupled receptors (GPCR) that couple to various effector systems, Therapeutic agents, including all clinically effective antipsychotics, interact with DA D2 receptors (D2R) and elicit both beneficial and unwanted side effects. In previous work, we have demonstrated that striatal D2Rs on medium spiny nervous (MSN) mediate- some of their actions through both G protein-dependent and independent mechanisms. These G protein-independent action occur through formation of B-arrestin2-dependent signaling complexes with components of the AKt/GSKS signaling pathway. Work during our previous U-19 NCDD grant period has identified novel small molecules based on, the scaffold of the anti-phychotic drug aripipraziole that can act as FUNGTIONALLY SELECTIVE ligands at theDb2R. These D2R are ligands are agonists at the G protein-mediated inhibition of cAMP production as well as antagonists at D2R/B-arrestin2 interactions or vice versa. Moreover, using pharmacologicai or genetic mouse rnodels of hyperdopaminergic function, compounds that are selective D2R/B arrestin2 interactions show potent antipsychotic activity profiles without associated cataleptic side effect. By comparison, these .these compounds elicit significant side effects in B-arrestin2 knockout mice where b2R/p-arrestih2 interactions are absent. These results suggest; that D2R;/B-arrestin2 signaling may protect against these unwanted effects. In Project 2, we will use cell and brain-region selective inactivation or rescue of components of the,D2R signaling pathways to validate our initial results and to determine the cellular and molecular events responsible for the antipsychotic profile(s) of the newly discovered functionally-selective D2R ligands. Aim 1: We will validate new mouse models of D2R/antipsychotic action through the use of mice in which B-arrestin2 and GSK3B have been selectively inactivated in D2R expressing in various neuronal populations; Aim 2: We will profile the new ligands in mice in which the endogenous D2R has been virally replaced by wild type B2R or a mutated D2R capable of selectively coupling to G protein or p-arrestin2 signaling. Aim 3; We will determine the cellular-and molecular profiles of the novel antipsychotic drugs by examining the biochemical, physiological and cellular events that correlate with the beneficial /side-effect actions of these agents in bur various animal model's. We anticipate that these efforts will lead to the proof-of-concept that targeting D2R/B-arrestin2 signaling will provide novel ligands for the development of more selective and effective therapeutic agents for clinical studies.