Spinophilin Signaling in the Striatum

描述（由申请人提供）：帕金森病（PD）是由从黑质投射到纹状体的含多巴胺神经元变性引起的近端疾病。这些神经元与称为树突棘的结构形成突触连接，树突棘位于表达D1多巴胺受体或D2多巴胺受体（分别为D1 R和D2 R）的中型多刺神经元（MSN）的两个亚群上。树突棘还从皮层接收激活棘中的钙依赖性信号的突触输入。因此，多巴胺的释放差异调节D1 R-和D2 R-含有MSN的树突棘内谷氨酸的作用。PD患者和帕金森病动物模型中的多巴胺耗竭导致纹状体MSN的树突棘丢失;然而，在短期啮齿动物研究中，棘丢失仅限于含D2 R的MSN。此外，来自几个实验室的新数据表明，多巴胺和其他神经递质对含有D1 R和D2 R的MSN的皮质纹状体突触的调节有差异。然而，很少有人知道纹状体MSN亚群之间的生化差异，大概占这些差异。 本项目研究了亲棘素在含有D1 R和D2 R的MSN中的作用。亲棘蛋白是一种支架蛋白，结合蛋白磷酸盐1（PP 1），F-肌动蛋白，和其他几种蛋白参与调节细胞信号和形态。在含有D1 R和D2 R的MSN中，亲棘素的整体敲除破坏皮质纹状体突触功能，并且还以年龄依赖性方式影响纹状体MSN的形态。我最近的研究表明，多巴胺耗竭增强了亲棘素与PP 1 <$1的相互作用，可能是调节了其他相关树突蛋白的去磷酸化。为了确定潜在的底物的spinophilin-PP 1复合物，我进行了蛋白质组学筛选，确定多个spinophilin-associated蛋白（SpAP）在正常的，成熟的纹状体，已知调节细胞形态，包括CaMKII。本实验室以前的研究表明多巴胺的缺乏会导致CaMKII的过度磷酸化。在这个职业发展奖，我将开发创新的转基因分子工具，以解决我的过度假设，即：多巴胺耗竭和老化差异调节纹状体MSN亚型的spinophilin依赖信号。两个目标将开始来测试这一假设：目标1将测试多巴胺耗竭以年龄依赖性方式改变亲棘素相互作用网络的假设。 目的2将使用新的转基因动物表达差异标记形式的亲棘素在D1 R或D2 R-含有MSN测试的假设，多巴胺耗竭改变亲棘素的相互作用网络中的细胞特异性的方式。 这些研究将大大提高我们对帕金森病动物模型中spinophilin介导的纹状体信号传导的理解，并将为这种疾病提供潜在的药物靶点。

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.