The intracellular plasticity of mitochondria, the endoplasmic reticulum and their interplay in schizophrenia and bipolar disorder

双相情感障碍(BPD)和精神分裂症(SCZ)是常见的、高度复杂的、仍然难以治疗的精神疾病，具有重叠的临床特征和遗传危险因素。在多个层面上仔细描述疾病生物学特征是着手确定疾病特定目标和开发新的个性化治疗策略的先决条件。多条证据表明BPD和SCZ存在线粒体缺陷。由于BPD和SCZ的研究显示BPD和SCZ的多种关键细胞功能紊乱，即已知由高度专业化的线粒体相关内质网(ER)膜(MAM)介导的钙稳态，我们假设BPD和SCZ受试者从诱导的多能干细胞(IPSCs)分化而来的神经元中，线粒体与ER的相互作用将存在疾病特异性缺陷。我们将利用BPD和SCZ受试者的IPSCs分化出的皮质神经元来实现以下三个相互关联的目标：目标1：我们将表征IPSC来源的皮质神经元中线粒体和内质网的分布和形态，并对MAM进行量化。我们将通过分析细胞内钙稳态来研究MAM差异的功能含义。目标2：我们将描述特定扰动对线粒体和内质网动力学以及MAM功能的影响，特别是在过氧化氢和氢化可的松诱导的细胞应激以及包括氯氮平、氟哌啶醇、利培酮、拉莫三嗪和锂在内的具有代表性的精神药理化合物存在的情况下。通过分析细胞应激源和注释小分子对患者衍生神经元的影响，我们将确定在扰动设置中未被掩盖的疾病特异性差异。目标3：我们将测试我们的假设，即GSK3-？参与了BPD和SCZ中两个MAM系链(VAPB和PTPIP51)的松动，这与越来越多的证据表明WNT/GSK3？通路在这些疾病的发病机制中调节失调是一致的。因此，我们将通过应用P100“减少代表性”的磷蛋白质组学分析，在我们的细胞疾病模型中识别细胞磷信号特征，以剖析线粒体和内质网动态差异的机制基础。成功完成这些目标将导致识别BPD和SCZ中线粒体和MAM的形态和分布的疾病特异性差异，以及疾病神经元对细胞应激的具体反应方式。这些研究还将提供对BPD和SCZ中异常的信号通路的见解，在基线和特定扰动的背景下。这些结果将为发现调节疾病特征的新的小分子的分析方法的开发奠定基础。

Bipolar disorder (BPD) and schizophrenia (SCZ) are common, highly complex and still difficult to treat psychiatric disorders sharing overlapping clinical features and genetic risk factors. A careful characterization of the disease biology at multiple levels is a prerequisite to proceed with the identification of disease-specific targets and the development of novel and personalized treatment strategies. Multiple lines of evidence suggest the existence of mitochondrial deficits in BPD and SCZ. Since studies in BPD and SCZ show disturbances in multiple crucial cellular functions i.e. calcium homeostasis known to be mediated by highly specialized mitochondria associated endoplasmic reticulum (ER) membranes (MAMs), we hypothesize that there will be disease-specific deficits in the interaction of mitochondria with the ER in neurons differentiated from induced pluripotent stem cells (iPSCs) of subjects with BPD and SCZ. We will address the following three interrelated aims using cortical neurons differentiated from iPSCs of subjects with BPD and SCZ:Aim 1: We will characterize the distribution and morphology of mitochondria and ER in iPSC-derived cortical neurons and quantify MAMs. We will study functional implications of differences in MAMs through analysis of intracellular calcium homeostasis.Aim 2: We will delineate the effects of specific perturbations on mitochondrial and ER dynamics and on the functionality of MAMs, specifically in the setting of cellular stress induced by H2O2 and hydrocortisone as well as in the presence of representative psychopharmacological compounds comprising clozapine, haloperidol, risperidone, lamotrigine and lithium. By profiling the effects of the cellular stressors and annotated small molecules on the patient-derived neurons, we will determine the disease-specific differences that are unmasked in the setting of the perturbations.Aim 3: We will test our hypothesis that GSK3-ß is involved in loosening of two MAM tethers (VAPB and PTPIP51) in BPD and SCZ, consistent with the growing evidence for dysregulation of the Wnt/GSK3ß pathway in the pathogenesis of these disorders. Therefore, we will identify cellular phosphosignaling signatures in our cellular disease models by applying the P100 “reduced-representation“ phosphoproteomic analysis to dissect the mechanistic underpinnings of the differences in the mitochondrial and ER dynamics.Successful completion of these aims will result in the identification of disease-specific differences in the morphology and distribution of mitochondria and MAMs in BPD and SCZ as well as the delineation of specific ways in which the disease neurons respond to cellular stress. The studies will also provide insights into signaling pathways that are aberrant in BPD and SCZ, at baseline and in the setting of specific perturbations. These results will lay the foundation for the development of assays for the discovery of novel small molecules that modulate the disease signatures.