Subcellular Glutamate Receptor Defects in Schizophrenia

描述(申请人提供)：该项目旨在研究精神分裂症患者和对照组尸检获得的脑组织中NMDA和AMPA谷氨酸受体亚单位和相互作用蛋白的表达、亚细胞定位和翻译后修饰。越来越多的证据表明，在这种疾病中，谷氨酸受体的转录和蛋白表达有区域特异性的变化。精神分裂症的谷氨酸假说得到了药理学证据的支持，这些证据表明，谷氨酸受体-信号复合体参与了谷氨酸受体-信号复合体的作用，其中包括谷氨酸受体相互作用蛋白，这些蛋白对正常的NMDA和AMPA受体组装、运输、插入质膜和从质膜移除、激活和降解至关重要。此前，我们实验室和其他实验室的研究已经详细说明了精神分裂症患者谷氨酸受体表达的变化。然而，除了少数例外，这些数据充其量也是不一致的，在某些情况下，mRNA和蛋白质水平的变化存在不同的极性。对于这些看似不同的结果，一种可能的解释是，精神分裂症的谷氨酸能异常可能包括谷氨酸受体运输的变化，这一概念与发现谷氨酸受体化学计量学变化但不是受体总数变化的研究一致。支持这一假设的是，我们发现精神分裂症细胞内AMPA和NMDA受体相互作用蛋白家族成员的mRNA和蛋白表达发生了强劲和一致的变化。我们假设精神分裂症患者脑内谷氨酸能异常包括内质网退出/滞留、运输、递送、树突定位以及NMDA或AMPA受体的循环/降解的改变。因此，我们建议进行与这些受体的合成、组装、运输和定位相关的新分子的转录本和蛋白质分析；受体亚基与对这些细胞过程至关重要的已知伴侣蛋白的免疫共沉淀研究；翻译后修饰亚基和相关蛋白质的蛋白质测量，包括磷酸化、糖基化和泛素化；以及皮质组织亚细胞组分中的蛋白质分析。这些研究将全面评估与精神分裂症中NMDA和AMPA谷氨酸受体合成、贩运、循环和降解相关的分子和细胞事件，强调可针对这种致残性疾病产生新的治疗方式的异常。

DESCRIPTION (provided by applicant): This project is designed to examine the expression, subcellular localization and posttranslational modifications of NMDA and AMPA glutamate receptor subunits and interacting proteins in autopsy-obtained brain tissue from patients with schizophrenia and a comparison group. Converging lines of evidence indicate that there are region specific changes in glutamate receptor transcript and protein expression in this illness. The glutamate hypothesis of schizophrenia is supported by pharmacological evidence suggesting involvement of glutamate receptor-signaling complexes, which includes glutamate receptor interacting proteins that are critical for normal NMDA and AMPA receptor assembly, trafficking, insertion in and removal from the plasma membrane, activation, and degradation. Previously, studies from our lab and others have detailed changes in glutamate receptor expression in schizophrenia. However, with a few exceptions, these data are inconsistent at best, and in some cases there is divergent polarity of changes in mRNA and protein levels. One possible explanation for these seemingly disparate results is that glutamatergic abnormalities in schizophrenia may include alterations in glutamate receptor trafficking, a notion consistent with studies that find alterations in glutamate receptor stoichiometry but not in the total number of receptors. Supporting this hypothesis, we have found robust and consistent changes in the expression of mRNA and protein for members of a family of intracellular AMPA and NMDA receptor interacting proteins in schizophrenia. We hypothesize that glutamatergic abnormalities in the schizophrenic brain include alterations in endoplasmic reticulum exit/retention, trafficking, delivery, dendritic localization and recycling/degradation of NMDA or AMPA receptors. Accordingly, we propose to perform transcript and protein analyses of novel molecules associated with synthesis, assembly, transport and localization of these receptors; co-immunoprecipitation studies of receptor subunits with known chaperone proteins critical for these cellular processes; protein measures of posttranslationally modified subunits and associated proteins, including phosphorylation, glycosylation, and ubiquitination; and protein assays in subcellular fractions from cortical tissue. These studies will comprehensively evaluate molecular and cellular events associated with NMDA and AMPA glutamate receptor synthesis, trafficking, recycling, and degradation in schizophrenia, highlighting abnormalities that can be targeted for the generation of novel treatment modalities for this disabling illness.