Signaling regulation in the striatum in Parkinson's disease

描述（由申请方提供）：G蛋白偶联受体激酶（GRK）和抑制蛋白协同作用，以确保G蛋白偶联受体快速终止G蛋白介导的信号传导。通过纹状体多巴胺受体的多巴胺能信号传导在控制正常和患病大脑中的多种形式的行为中起关键作用。多巴胺受体信号传导的缺失与帕金森病（PD）和多巴胺替代疗法引起的运动并发症（如L-DOPA诱导的运动障碍）密切相关。多巴胺受体经历GRK和arrestin依赖性脱敏，在这个过程中的缺陷可能是由多巴胺的损失或多巴胺能药物在PD引起的信号异常的基础。慢病毒介导的GRK 6在多巴胺耗尽的纹状体中的过表达使PD的啮齿动物和灵长类动物模型中的行为和多巴胺受体信号正常化，这表明GRK在调节大脑中的多巴胺受体中起关键作用。本项目旨在探讨GRK和arrestins在活体动物多巴胺能行为调节中的作用以及GRK功能的精细分子机制。第一个目的是研究GRK亚型在拮抗左旋多巴诱导的偏侧帕金森病大鼠旋转和行为敏感化中的特定作用。我们将注射编码野生型GRK同种型、具有不同功能选择性失活的突变GRK或GRK microRNA的慢病毒，以将选择的同种型敲低到多巴胺耗尽的纹状体中，并测试重复给予L-DOPA后的旋转行为。目的2旨在测试抑制蛋白和GRK的同时过表达在抑制L-DOPA诱导的运动症状方面是否比相同GRK单独过表达更有效。在目标3中，我们将研究由GRK表达或功能的扰动引起的下游信号通路的改变。在目标4中，将检查利用受体脱敏过程来改善帕金森病治疗的可行性。这些实验的结果将有助于理清GRK和arrestin异构体在体内调节脑中多巴胺能信号传导中的特定作用。这些研究将为开发新的治疗方法铺平道路，以控制帕金森病的运动缺陷和左旋多巴治疗的并发症。公共卫生相关性：帕金森氏病是一种神经退行性疾病，会导致运动问题，用左旋多巴治疗，左旋多巴是一种有效的药物，但随着时间的推移会失去效力，并有严重的副作用。我们不知道是什么原因导致左旋多巴治疗的问题，也不知道它是如何产生副作用的。该项目旨在探索被称为抑制蛋白和G蛋白偶联受体激酶的蛋白质是否在左旋多巴治疗的并发症中发挥作用。

DESCRIPTION (provided by applicant): G protein-coupled receptor kinases (GRK) and arrestins act in concert to ensure rapid termination of G protein-mediated signaling by G protein-coupled receptors. Dopaminergic signaling via striatal dopamine receptors play a critical role in controlling multiple forms of behavior in the normal and diseased brain. Abnormalities of signaling by dopamine receptors have been strongly implicated in Parkinson's disease (PD) and motor complications caused by dopamine replacement therapy such as L-DOPA-induced dyskinesia. Dopamine receptors undergo GRK- and arrestin-dependent desensitization, and deficits in this process may underlie signaling abnormalities caused by the loss of dopamine or by dopaminergic drugs in PD. The lentivirus-mediated overexpression of GRK6 in the dopamine-depleted striatum normalizes behavior and dopamine receptor signaling in the rodent and primate animal models of PD, suggesting a critical role for GRKs in the regulation of dopamine receptors in the brain. This project is designed to explore the role of GRKs and arrestins in the dopaminergic regulation of behavior in live animals as well as fine molecular mechanisms of the GRK function in vivo. First Aim will examine specific roles of GRK isoforms in antagonizing L-DOPA- induced rotations and behavioral sensitization to L-DOPA in hemiparkinsonian rats. We will inject lentiviruses encoding wild type GRK isoforms, mutant GRKs with different functions selectively disabled, or GRK microRNAs to knockdown select isoforms into the dopamine-depleted striatum and test for rotational behavior following repeated L-DOPA administration. The Aim 2 is designed to test whether simultaneous overexpression of an arrestin and a GRK is more potent than overexpression of the same GRK alone in suppressing L-DOPA-induced motor symptoms. In Aim 3, we will examine the alterations in down-stream signaling pathways caused by perturbations in the GRK expression or function. In Aim 4, the feasibility of harnessing the receptor desensitization process to improve therapy in Parkinson's disease will be examined. The results of these experiments will help to sort out specific roles of GRK and arrestin isoforms in regulating dopaminergic signaling in the brain in vivo. The studies will pave the way to development of novel therapeutic approaches to control motor deficits in Parkinsons' disease and complications of L-DOPA therapy. PUBLIC HEALTH RELEVANCE: Parkinson's disease is a neurodegenerative disorder that causes movement problems treated with levodopa, which is an effective drug but looses effectiveness in time and has severe side effects. We do not know what causes problems with levodopa therapy or how its produces its side effects. This project is designed to explore whether the proteins called arrestins and G protein-coupled receptor kinases play a role in complications of the levodopa therapy.