Phosphatase-Dependent Regulation of Dopamine D3 Receptor-Adenylyl Cyclase Complexes

多巴胺是大脑中一种重要的化学物质。在大脑中，多巴胺控制着一些功能，如运动、记忆、决策和快乐。这些功能之所以成为可能，是因为多巴胺附着在一种叫做受体的特殊蛋白质上。多巴胺受体位于细胞的外部。已鉴定出5种多巴胺受体，分别为D1、D2、D3、D4和D5。我们的初步研究表明，多巴胺附着在D3上选择性地促进了与细胞外部另一种称为腺苷酸环化酶5 （AC5）的蛋白质的相互作用。由于研究提示D3和AC5在大脑行为调节中的作用，我们的目标是通过NSERC资金来阐明D3和AC5在大脑中共同作用的生化机制。我们将探讨两种生化反应，即磷酸化（一种向蛋白质中添加磷酸盐的过程）和去磷酸化（一种从蛋白质中去除磷酸盐的过程）如何控制D3和AC5之间的串扰。我们实验室所做的初步工作表明，多巴胺附着在D3上后，D3会发生去磷酸化。D3去磷酸化与AC5的存在密切相关。我们的假设是AC5是磷酸酶的中枢。磷酸酶是执行蛋白质去磷酸化（去除磷酸盐）的特殊酶。我们最初的实验也提示D3去磷酸化在触发D3与AC5分离中的作用。D3与AC5的分离开启了细胞内的生化反应。我们建议确定由AC5控制的磷酸酶作用于D3去磷酸化，并揭示D3和AC5之间串扰的分子机制。这项研究将使用在塑料培养皿中生长的细胞和神经元、重组DNA技术和生化分析来完成。我们相信，这项由nserc资助的研究将获得的机制信息将有助于设计专门针对D3和AC5二重奏的工具。我们相信这些工具将有助于理解大脑行为是如何被D3和AC5的协同作用所控制的。

Dopamine is an important chemical of the brain. In the brain, dopamine controls several functions such as movement, memory, decision making and pleasure. These functions are made possible because dopamine attaches to specialized proteins called receptors. The receptors for dopamine are located on the cell's exterior. Five dopamine receptors named D1, D2, D3, D4 and D5 have been identified. Our preliminary studies suggest that the attachment of dopamine to D3 selectively promotes the interaction with another protein in cell's exterior called adenylyl cyclase 5 (a.k.a. AC5). As studies hint for a role of D3 and AC5 in the modulation of brain behaviors, we aim with NSERC monies to elucidate the biochemical mechanisms by which D3 and AC5 work together in the brain. We will explore how two biochemical reactions called phosphorylation (a process that adds phosphate to proteins) and dephosphorylation (a process that removes phosphate from proteins) control the crosstalk between D3 and AC5. Preliminary work done in our laboratory suggests a dephosphorylation of D3 following the attachment of dopamine to D3. The D3 dephophorylation is intimately related to the presence of AC5. Our hypothesis is that AC5 serves as a hub for phosphatases. Phosphatases are specialized enzymes performing dephosphorylation (removing phosphate) of proteins. Our initial experiments hint also for a role of D3 dephosphorylation in triggering the separation of D3 from AC5. The separation of D3 from AC5 turns on biochemical reactions inside the cells. We propose to identify the phosphatases controlled by AC5 that act on D3 dephophorylation and to uncover the molecular mechanisms involved in the crosstalk between D3 and AC5. The research will be done using cells and neurons growing in plastic dishes, recombinant DNA techniques and biochemical assays. We believe that the mechanistic information that will be gained with this NSERC-funded research will facilitate the design of tools to target specifically the D3 and AC5 duet. We trust these tools will be helpful to understand how brain behaviors are controlled by the concerted actions of D3 and AC5.