Molecular dissection of synaptic dysfunction in mental disorders

多基因脑部疾病的遗传分析，如自闭症谱系障碍（ASD）和精神分裂症 (SZ)已经揭示了“突触功能障碍”是这些疾病的关键细胞基质。然而，翻译这个 突触假说到体外疾病建模和提取疾病相关的生物信息， 一直具有挑战性。PI先前已经建立了SZ的人类神经元模型，结合同基因 基因组工程，患者来源的诱导多能干细胞（iPSC），和诱导神经元 分化（iN细胞）。突触细胞粘附分子Neurexin-1突变的人类神经元 （NRXN 1，2p16.3），SZ的真正风险等位基因，显示兴奋性突触强度的缺陷， 神经递质释放概率以及钙/钙调蛋白依赖性的一致上调 丝氨酸蛋白激酶（CASK）蛋白水平，其机制目前尚不清楚。它仍然是 尚不清楚这些表型如何产生并导致突触病理学和异常神经元网络 与疾病有关。在这项资助中，我们的目标是了解细胞类型和发育特异性 NRXN 1-CASK相互作用在正常突触发育中的功能及其对突触发育的机制贡献 SZ.使用突触分子作为代理，我们将剖析如何在突触通路中断可以启动或 积极参与SZ。我们将通过研究NRXN 1突变体中异常的CASK信号来实现这一点。 背景（目的1），使用CASK KO诱导的人突触研究CASK的正常功能。 神经元（目的2），并揭示关键细胞事件介导的NRXN 1和CASK在人类前脑 使用KO皮质球体模型进行开发（Aim 3）。我们的工作整合了成像技术， 电生理学、生物化学和单细胞RNA-seq，采用等基因 来自多种遗传和性别背景的工程化和患者来源的iPSC，纯 诱导的神经元亚型具有确定的突触特征和3-D皮质球状体的分化 具有细胞特征。这项补助金的发现将提供机械的理解 神经精神疾病的分子和细胞基础，这些信息将转化为其他 突触障碍，包括智力残疾、自闭症、双相情感障碍和情绪障碍。

Genetic analyses of polygenic brain disorders, such as autism spectrum disorders (ASDs) and schizophrenia (SZ), have revealed “synaptic dysfunction” as a key cellular substrate for these disorders. Yet, translating this synaptic hypothesis to in vitro disease modeling and extracting disease-relevant biological information has been challenging. The PI has previously established a human neuronal model of SZ, combining isogenic genome engineering, patient-derived induced pluripotent stem cells (iPSCs), and induced neuronal differentiation (iN cells). Human neurons bearing mutations in the synaptic cell adhesion molecule Neurexin-1 (NRXN1, 2p16.3), a bona fide risk allele for SZ, display deficits in excitatory synaptic strength and neurotransmitter release probability as well as a consistent upregulation of calcium/calmodulin-dependent serine protein kinase (CASK) protein level, by which the mechanism is currently not understood. It remains unclear how these phenotypes arise and lead to synaptic pathology and abnormal neuronal networks implicated in the disease. In this grant, we aim to understand the cell type- and developmental-specific functions of NRXN1-CASK interaction in normal synapse development and their mechanistic contributions to SZ. Using synaptic molecules as a proxy, we will dissect how disruptions in the synaptic pathway can prime or actively participate in SZ. We will achieve this by studying aberrant CASK signaling in NRXN1 mutant background (Aim 1), investigating CASK’s normal function at human synapses using CASK KO induced neurons (Aim 2) and by revealing key cellular events mediated by NRXN1 and CASK during human forebrain development using KO cortical spheroid models (Aim 3). Our work integrates techniques in imaging, electrophysiology, biochemistry and single cell RNA-seq with rigorous experimental designs using isogenic engineered and patient-derived iPSCs from multiple genetic and gender backgrounds, differentiation of pure induced neuronal subtypes with defined synaptic characteristics and differentiation of 3-D cortical spheroids with characterized cellular features. Findings of this grant will provide mechanistic understanding of the molecular and cellular underpinnings of neuropsychiatric disorders and such information will translate to other disorders of the synapse, including intellectual disability, ASDs, and bipolar and mood disorders.