Spinophilin Signaling in the Striatum

描述（由申请人提供）：帕金森病（PD）是由从黑质向纹状体投射的含有多巴胺的神经元变性引起的。这些神经元与树突棘的结构形成突触连接，树突棘位于中棘神经元（MSN）的两个亚群上，分别表达D1多巴胺受体或D2多巴胺受体（分别为D1R和D2R）。树突棘也接受来自皮质的谷氨酸能突触输入，激活棘中的钙依赖信号。因此，多巴胺的释放对含有D1R-和d2r -的msn的树突棘中谷氨酸的作用有不同的调节作用。PD患者和帕金森动物模型中的多巴胺耗竭导致纹状体mns树突棘的丢失；然而，在短期啮齿类动物研究中，脊柱损失仅限于含有d2r的msn。此外，来自几个实验室的新数据表明，皮质纹状体突触连接到含有D1R和d2r的msn上，受到多巴胺和其他神经递质的不同调节。然而，对纹状体MSN亚群之间的生化差异知之甚少，这些差异可能是造成这些差异的原因。本项目研究嗜脊髓蛋白在含D1R-和d2r -的msn中的作用。嗜脊髓蛋白是一种结合磷酸蛋白1 （PP1）、f -肌动蛋白和其他几种参与调节细胞信号传导和形态的蛋白的支架蛋白。嗜脊髓蛋白的整体敲除会破坏含有D1R-和d2r -的皮质纹状体突触功能，并以年龄依赖的方式影响纹状体msn的形态。我最近的研究表明，多巴胺耗竭增强了嗜脊髓蛋白与PP1¿1的相互作用；可能是调节其他相关树突蛋白的去磷酸化。为了鉴定嗜脊髓蛋白- pp1复合物的潜在底物，我进行了蛋白质组学筛选，鉴定了正常成熟纹状体中已知调节细胞形态的多种嗜脊髓蛋白相关蛋白（SpAPs），包括CaMKII。本实验室先前的研究表明，多巴胺耗竭会导致CaMKII的过度磷酸化。在这个职业发展奖项中，我将开发创新的转基因分子工具来解决我的首要假设：多巴胺消耗和衰老在纹状体MSN亚型中差异调节脊髓蛋白依赖的信号。两个目标将开始测试这一假设：目标1将测试多巴胺消耗以年龄依赖的方式改变嗜脊髓蛋白相互作用网络的假设。目的2将使用新型转基因动物，在含有D1R-或D2R-的msn中表达不同标记形式的嗜脊髓蛋白，以验证多巴胺消耗以细胞特异性方式改变嗜脊髓蛋白相互作用网络的假设。这些研究将极大地增强我们对PD动物模型中脊髓球蛋白介导的纹状体信号传导的理解，并为该疾病的潜在药物靶点提供信息。

DESCRIPTION (provided by applicant): Parkinson disease (PD) is proximally caused by degeneration of dopamine containing neurons that project from the Substantial Nigra to the striatum. These neurons form synaptic connections with structures termed dendritic spines that reside on two subpopulations of the medium spiny neuron (MSN) that express either D1 dopamine receptors or D2 dopamine receptors (D1R and D2R, respectively). The dendritic spines also receive glutamatergic synaptic inputs from the cortex that activates calcium-dependent signaling in spines. Thus, the release of dopamine differentially modulates the actions of glutamate within the dendritic spines of D1R- and D2R-containing MSNs. Dopamine-depletion in PD patients and in parkinsonian animal models results in loss of dendritic spines from striatal MSNs; however, spine loss is restricted to D2R-containing MSNs in short-term rodent studies. Moreover, emerging data from several labs indicate that corticostriatal synapses onto D1R- and D2R-containing MSNs are differentially regulated by dopamine and other neurotransmitters. However, very little is known about the biochemical differences between striatal MSN subpopulations that presumably account for these differences. This project investigates the roles of spinophilin in D1R- and D2R-containing MSNs. Spinophilin is a scaffolding protein that binds protein phosphates 1 (PP1), F-actin, and several other proteins involved in regulating cell signaling and morphology. The global knockout of spinophilin disrupts corticostriatal synaptic function in both D1R- and D2R-containing MSNs, and also affects the morphology of striatal MSNs in an age- dependent manner. My recent studies showed that dopamine depletion enhances the interaction of spinophilin with PP1¿1; presumably modulating the dephosphorylation of other associated dendritic proteins. In order to identify potential substrates of the spinophilin-PP1 complex, I performed a proteomics screen, identifying multiple spinophilin-associated proteins (SpAPs) in normal, mature striatum that are known to regulate cell morphology, including CaMKII. Previous studies in this lab showed that dopamine depletion leads to hyper- phosphorylation of CaMKII. In this career development award I will develop innovative transgenic molecular tools to address my over-arching hypothesis that: dopamine depletion and aging differentially regulate spinophilin-dependent signaling in striatal MSN subtypes. Two aims will begin to test this hypothesis: Aim 1 will test the hypothesis that dopamine depletion alters the spinophilin interaction network in an age-dependent manner. Aim 2 will use novel transgenic animals expressing differentially tagged forms of spinophilin in D1R- or D2R- containing MSNs to test the hypothesis that dopamine depletion alters the spinophilin interaction network in a cell-specific manner. These studies will greatly enhance our understanding of spinophilin-mediated striatal signaling in animal models of PD and will inform potential drug targets for this disorder. PUBLIC HEALTH RELEVANCE: Parkinson disease (PD) is a debilitating neurodegenerative disorder with 50,000 new cases annually. The current proposal will utilize cutting edge techniques to better understand changes that occur in animal models of the disease. The information learned will hopefully lead to a better understanding of, and new ways to treat, PD.