mGluR5 hypoactivity is integral to glutamatergic dysregulation in schizophrenia

项目摘要 （显著性）多条证据表明mGluR 5信号传导与病理生理学有关， 精神分裂症的治疗; mGluR 5信号转导的可能失调及其病理生理作用 目前尚不清楚。最近，我们发现直接证据表明，在死后， 精神分裂症患者的背外侧前额叶皮层（DLPFC）。mGluR 5与 NMDA受体（GluN）复合物在突触后致密区（PSD），这两条通路促进了突触后致密区（PSD）的形成。 彼此的活动。（初步研究）我们检测了激动剂诱导的mGluR 5信号传导的激活 在来自17对匹配患者的死后背外侧前额叶皮层（DLPFC）中， 对照我们发现mGluR 5受体激活下游的三条途径显著减少;即， 与对照组相比，Gq/11活化和PI 3 K和支架蛋白的募集（P<0.01）。这 调节异常伴随着mGluR 5磷酸化的改变，这对受体的表达很重要。 脱敏，以及mGluR 5与RGS 4，Preso 1，norbin和tamalin的相关性，这些对于 表面表达和聚类。重要的是，我们发现了支持互惠促进中断的证据 在精神分裂症中mGluR 5和GluN信号之间的联系，因此其中一个功能减退可以进一步损害 另一精神分裂症与mGluR 5信号传导活性低下有关， 改变受体复合物中mGluR 5磷酸化和蛋白质-蛋白质相互作用（PrPrIs）。mGluR5 功能减退可导致GluN信号传导功能减退，反之亦然，通过破坏相互作用， 便利化PrPrIs的相互作用可能是一个点的病因学因素的收敛。（具体目标） 进一步表征精神分裂症中mGluR 5活性低下及其与GluN信号传导的相互作用，我们将 检查DLPFC中mGluR 5对GluN信号传导的低活性的分子基础，反之亦然。 患者与对照组比较。(Aim 1）。我们的初步数据和最近的研究指出PrPrIs作为底物 在此基础上，各种分子改变汇聚并促使代谢能失调。结合 发现和定量蛋白质组学，我们将分析PrPrI在mGluR 5-GluN相互作用组中的改变， 患者在基础水平和响应受体激活（目标2）。PrPrI在相互作用组中的改变 可以追溯到它们在基因组、转录组和蛋白质组水平上的病因学基础。切割 边缘系统生物学算法允许我们利用目前可用的最大基因组学数据集， 插补相同数量受试者的DLPFC转录组学数据。遗传变异，插补转录组学 结果，沿着定量PSD蛋白质组学结果将使用热投射到相互作用组上 基于扩散的算法（Aim 3）。这将确定病因学上的重大和潜在的目标 子网络中的相互作用。（影响）我们将建立mGluR 5功能减退作为不可或缺的谷氨酸能 精神分裂症的失调，并确定病因学基础和潜在的干预点。

Project Summary (Significance) Multiple lines of evidence have implicated mGluR5 signaling for the pathophysiology and treatment of schizophrenia; yet possible dysregulation of mGluR5 signaling and their pathophysiologic roles are presently unknown. Recently, we found direct evidence for reduced mGluR5 signaling in the postmortem dorsolateral prefrontal cortex (DLPFC) of patients with schizophrenia. mGluR5 is physically connected with NMDA receptor (GluN) complexes in the postsynaptic density (PSD) and these two pathways facilitate the activity of each other. (Preliminary Studies) We examined the agonist-induced activation of mGluR5 signaling in the postmortem dorsolateral prefrontal cortex (DLPFC) derived from 17 matched pairs of patients and controls. We found a striking reduction in three pathways downstream to mGluR5 receptor activation; namely, Gq/11 activation and recruitment of PI3K and scaffolding proteins compared to controls (P<0.01). This dysregulation was accompanied by alterations in phosphorylation of mGluR5, important for receptor desensitization, and in mGluR5 association with RGS4, Preso 1, norbin and tamalin, which are critical for surface expression and clustering. Importantly, we find evidence supporting disruption of reciprocal facilitation between mGluR5 and GluN signaling in schizophrenia and thus hypofunction of one can further compromise the other. (Scientific Premise) Schizophrenia is associated with mGluR5 signaling hypoactivity mediated by altered mGluR5 phosphorylation and protein – protein interactions (PrPrIs) in the receptor complexes. mGluR5 hypofunction can contribute to GluN signaling hypoactivity and vice versa via disruption of reciprocal facilitation. PrPrIs in the interactome may be a point of convergence for etiologic factors. (Specific Aims) To further characterize mGluR5 hypoactivity and its interplay with GluN signaling in schizophrenia, we will examine molecular underpinnings for mGluR5 hypoactivity on GluN signaling and vice versa in the DLPFC of patients compared to controls. (Aim 1). Our preliminary data and recent studies point to PrPrIs as substrates upon which various molecular alterations converge and precipitate glutamatergic dysregulation. Combining discovery and quantitative proteomics, we will analyze PrPrI alterations in the mGluR5-GluN interactome in patients at the basal level and in response to receptor activation (Aim 2). PrPrI alterations in the interactome can be traced to their etiologic underpinnings at the genomic, transcriptomic and proteomic levels. Cutting edge systems biology algorithms permit us to leverage largest genomics data sets presently available and impute DLPFC transcriptomics data of the same number of subjects. Genetic variants, imputed transcriptomic results, along with quantitative PSD proteomics results will be projected onto the interactome using heat diffusion based algorithms (Aim 3). This will identify etiologically significant and potentially targetable subnetworks in the interactome. (Impact) We will establish mGluR5 hypofunction as integral to glutamatergic dysregulation in schizophrenia and identify etiologic underpinnings and potential points of intervention.