Cellular and Molecular Analysis of the Schizophrenia and Autism Spectrum Disorder gene Transcription Factor 4 (TCF4)

项目概要：神经发育障碍，包括精神分裂症和自闭症谱系 自闭症（ASD）是慢性的和使人衰弱的，具有相对未知的病因学和病理生理学。最近 在人群水平上理解这些疾病的遗传结构的进展导致了 许多遗传风险因素的识别。然而，在大多数情况下， 所鉴定的基因的相关功能是未知的 仍然很困难。在我们的提案中，我们概述了确定治疗靶点的路线图， 并提供初步数据，表明我们的方法是有价值的。我们建议使用 两个模型系统，一个细胞自主模型，其中精神分裂症和ASD基因TCF 4的表达 使用子宫内电穿孔和具有组成性转录因子4的小鼠模型来操作转录因子4。 一个TCF 4等位基因的种系截短，其模拟皮特-霍普金斯综合征（PTHS）。我们将描述 使用脑切片电生理学、细胞生物学和共聚焦成像得到神经元表型。 鉴定的表型将被评价为潜在的病理生理学和治疗的发展。 治疗将基于我们对相关分子机制的新认识。 在Aim 1中，我们假设TCF 4转录调节内在神经元兴奋性，因此 抑制TCF 4表达将导致与PTHS相关的异常神经元生理学。我们 初步数据表明，在子宫内敲低PFC第2/3层锥体细胞中的TCF 4， 异常的内在兴奋性和异位尖峰频率适应。我们展示了 这些表型与后超极化（AHP）的增加有关。使用一种新 分子轮廓技术（iTRAP），我们已经确定了两个候选的离子通道，调节 TCF 4，可能是PTHS中观察到的认知表型的基础。为了验证这些靶基因，我们建议 药理学拯救和分子表型实验。在目标2中，我们建议使用小鼠模型 的PTHS。我们的初步数据表明，TCF 4 +/tr小鼠的PFC层2/3神经元表现出类似的内在 当使用shRNA/Crispr构建体敲低TCF 4时，我们观察到的兴奋性缺陷。我们提出 细胞和分子实验，以确定这种表型的机制与未来的目标 用药理学来挽救这些小鼠的行为缺陷。在目标3中，我们建议确定 在PTHS小鼠模型中，神经转录组在发育过程中发生改变。我们假设， TCF 4 +/tr对神经转录组的分子影响将提供机制和病理学意义。 关于PTHS和潜在的其他特发性ASD的见解。这些目标旨在确定 用于治疗PTHS的治疗靶点。

PROJECT SUMMARY: Neurodevelopmental disorders including Schizophrenia and Autism spectrum disorders (ASD) are chronic and debilitating, with relatively unknown etiology and pathophysiology. Recent progress towards understanding the genetic architecture of these disorders at the population level has led to the identification of many genetic risk factors. However, in most cases the molecular mechanism of risk and the relevant functions of the identified genes are not known and therefore identifying therapeutic targets remains difficult. In our proposal we have outlined a roadmap for the identification of therapeutic targets for psychiatric disorders and provide preliminary data that suggests our approach has merit. We propose to use two model systems, a cell autonomous model in which expression of the schizophrenia and ASD gene TCF4 (transcription factor 4) is manipulated using in utero electroporation and a mouse model that has a constitutive germline truncation of one TCF4 allele that models Pitt-Hopkins syndrome (PTHS). We will characterize the resulting neuronal phenotypes using brain slice electrophysiology, cell biology, and confocal imaging. Identified phenotypes will be evaluated as potentially pathophysiological and the development of therapeutic treatments will be based on our emerging understanding of the molecular mechanism responsible. In Aim1, we hypothesize that TCF4 transcriptionally regulates intrinsic neuronal excitability and therefore suppression of TCF4 expression will result in abnormal neuronal physiology relevant to PTHS. Our preliminary data suggest that in utero knockdown of TCF4 in layer 2/3 pyramidal cells of the PFC results in abnormal intrinsic excitability and ectopic spike-frequency adaptation. We show the cellular mechanisms of these phenotypes are associated with an increase in the afterhyperpolarization (AHP). Using a novel molecular profiling technique (iTRAP) we have identified two candidate ion channels that are regulated by TCF4 and may underlie cognitive phenotypes observed in PTHS. To validate these target genes, we propose pharmacological rescue and molecular phenocopy experiments. In Aim 2, we propose to use a mouse model of PTHS. Our preliminary data indicates PFC layer 2/3 neurons from TCF4+/tr mice show similar intrinsic excitability deficits to what we observe when TCF4 is knockdown using shRNA/Crispr constructs. We propose cellular and molecular experiments to identify the mechanisms underlying this phenotype with the future goal of using pharmacology to rescue behavioral deficits in these mice. In Aim 3, we propose to identify how the neural transcriptome is altered across development in PTHS mouse model. We hypothesize that identifying molecular consequences of TCF4+/tr on the neural transcriptome will provide mechanistic and pathological insight about PTHS and potentially other idiopathic ASDs. Together, these Aims are designed to identify therapeutic targets for treatment of PTHS.