Protein Arginine Methyltransferase Activity Modulates Dopaminergic Signaling

描述(申请人提供)：多巴胺信号缺陷与精神分裂症、药物成瘾、抑郁症和帕金森氏症有关。然而，人类大脑令人难以置信的复杂性使得这些复杂疾病背后的生理基础和分子机制在很大程度上不得而知。调节信号转导途径的一种方式是通过信号蛋白的翻译后修饰。翻译后修饰是指在蛋白质合成后改变其性质的共价加工事件，如活性状态、定位、周转或与其他蛋白质的相互作用。最近，精氨酸甲基化(由蛋白质精氨酸甲基转移酶/PRMTs催化)已开始成为蛋白质功能的重要调节因子。我们在小圆虫(线虫)线虫上的实验揭示了PRMT在调节内源性多巴胺信号方面的作用，我们利用人类细胞培养中的人D2多巴胺受体证实了这一发现。线虫是已知整个神经系统(302个神经元)的发育谱系、物理位置和突触连接的唯一生物。重要的是，线虫的行为受到许多影响人类神经系统功能的化学物质的调节，包括神经递质多巴胺。作为我们了解不同调控机制如何协调调节G蛋白偶联信号的长期目标的重要一步，这项应用的总体目标是具体确定精氨酸甲基化调节人类D2B蛋白偶联受体(GPCR)功能的机制。在这里，我们建议使用生化、蛋白质组学和细胞生物学方法来了解精氨酸甲基化如何调节多巴胺能信号转导。我们将：(1)确定甲基化对D2-Galphai/o结合、激活和通过腺苷环化酶传递信号的影响，以及(2)鉴定人类D2中甲基化的精氨酸并建立其功能意义。总之，这些研究将定义一种调节G蛋白偶联信号转导的新方法，从而有望识别有选择性地治疗与多巴胺信号调节失调相关的神经和精神疾病的新治疗方法。

DESCRIPTION (provided by applicant): Defects in dopamine signaling have been linked to schizophrenia, drug addiction, depression and Parkinson's Disease. However, the incredible complexity of the human brain has left the physiological basis and molecular mechanisms underlying these complex diseases largely unknown. One way in which signal transduction pathways can be regulated is via the post-translational modification of signaling proteins. Post-translational modifications are covalent processing events that change the properties of a protein after its synthesis, such as its activity state, localization, turnover or interactions wit other proteins. Recently, methylation of the amino acid arginine (catalyzed by protein arginine methyltransferases/PRMTs) has begun to emerge as an important regulator of protein function. Our experiments in the small round worm (nematode) C. elegans have revealed a role for a PRMT in regulating endogenous dopamine signaling, and we corroborated this finding using the human D2 dopamine receptor in human cell culture. C. elegans is the only organism for which the developmental lineage, physical positions and synaptic connectivity of the entire nervous system (302 neurons) are known. Importantly, C. elegans behaviors are modulated by many of the same chemicals that affect human nervous system function, including the neurotransmitter dopamine. As an important step towards our long-term goal of understanding how diverse regulatory mechanisms coordinate to regulate G protein-coupled signaling, the overall objective of this application is to determine specifically the mechanism by which arginine methylation regulates human D2 G protein-coupled receptor (GPCR) function. Herein we propose to use biochemical, proteomic, and cell biological approaches to understand how arginine methylation regulates dopaminergic signal transduction. We will: (1) determine the effect of methylation on D2 - Galphai/o association, activation and signaling through adenylyl cyclase, and (2) identify methylated arginines in human D2 and establish their functional significance. Together, these studies will define a new means of regulating G protein-coupled signal transduction and thus are expected to lead to the identification of novel therapeutic approaches to selectively treat neurological and psychiatric disorders that are associated with dysregulation of dopamine signaling.