Genes and developmental signaling pathways in neuropsychiatric disorders

描述（申请人提供）：哺乳动物皮层的发育是一个复杂的过程，需要神经元增殖、迁移、神经突生长和突触发生的精确协调。皮质生成缺陷被认为是包括精神分裂症（SCZ）在内的几种神经精神疾病的基础。在过去的十年中，一些参与神经发育的基因与SCZ和相关疾病有关。这些基因中的许多在典型的WNT或Reelin （RELN）信号通路中起作用，它们分别在增殖和迁移中起核心作用。传统上认为，这些通路在神经元发育的不同时期独立作用。然而，在这些途径之间存在共同的分子因子，如DISC1。我们的总体假设是WNT和RELN通路相互作用，调节增殖和迁移之间的发育转换。此外，我们假设这些通路之间共享的基因（如DISC1）的破坏会导致精神疾病的风险增加。我们的实验室已经建立了等基因人类诱导多能干细胞（iPSCs），其在靠近chr（1;11）平衡易位位点的DISC1位点上有一个靶向突变，该位点与主要精神障碍有关。我们将使用这些细胞系来解决这种与疾病相关的突变是否以及如何影响某些神经发育过程。重要的是，观察到的表型将在SCZ携带chr（1;11）易位的人类受试者的hiPSCs中进行检查。此外，为了检查分子和细胞表型是否延伸到DISC1破坏之外，将对与精神疾病相关的CNVs的SCZ患者的hiPSCs进行有限的分析。为了补充这些体外研究，将同时利用死后人类脑组织和啮齿动物模型来建立关键发现的体内相关性。在目的1中，我们在神经分化过程中检测了DISC1亚型在等基因和患者来源的野生型和突变系中的表达。我们通过基因表达谱、形态分析和电生理分析来分析这些神经元的成熟。在Aim 2中，我们研究了WNT和RELN信号转导途径，并比较了DISC1中断与scz连锁拷贝数变异（cnv）对这些途径的影响。最后，在Aim 3中，我们通过子宫内电穿孔敲除或过表达基因和移植含有这些破坏的人类npc的互补方法，分析了DISC1破坏和scz相关cnv对啮齿动物胚胎脑内增殖和迁移的影响。综上所述，我们的目标是确定这些突变的影响是如何汇聚在一起，导致皮层回路的改变和精神疾病的发病。根据这项研究计划，我们将采取初步措施，比较对精神疾病风险有强烈影响的特定基因破坏如何影响人类神经元细胞的发育信号通路和过程。

DESCRIPTION (provided by applicant): The development of the mammalian cortex is a complex process that requires the precise coordination of neuronal proliferation, migration, neurite outgrowth and synaptogenesis. Defects in corticogenesis are thought to underlie aspects of several neuropsychiatric disorders including schizophrenia (SCZ). In the past decade, several genes involved in neurodevelopment have been linked to SCZ and related disorders. A number of these genes act in either the canonical WNT or Reelin (RELN) signaling pathways, which have central roles in proliferation and migration, respectively. These pathways are traditionally thought to act independently at different times in the development of a neuron. However, shared molecular factors such as DISC1 exist between these pathways. Our overarching hypothesis is that the WNT and RELN pathways interact to regulate the developmental switch between proliferation and migration. Further, we posit that disruption of genes shared between these pathways, such as DISC1, lead to increased risk for psychiatric disorders. Our lab has established isogenic human induced pluripotent stem cells (iPSCs) that have a targeted mutation at the DISC1 locus near the site of a chr(1;11) balanced translocation linked to major mental disorders. We will use these lines to address if and how this disease-relevant mutation affects certain neurodevelopmental processes. Importantly, phenotypes observed will be examined in hiPSCs derived from human subjects with SCZ harboring the chr(1;11) translocation. Further, in order to examine whether the molecular and cellular phenotypes extend beyond DISC1 disruption, a limited analysis will be performed in hiPSCs from SCZ patients with CNVs linked to mental illness. To complement these in vitro studies, postmortem human brain tissue and rodent models will be utilized in parallel to establish the in vivo relevance of key findings. In Aim 1, we examine DISC1 isoform expression in isogenic and patient-derived wild-type and mutant lines over neuronal differentiation. We analyze the maturation of these neurons via gene expression profiling, morphometric analyses, and electrophysiological assays. In Aim 2, we investigate the WNT and RELN signal transduction pathways, and compare the impact of DISC1 disruption with SCZ-linked copy number variants (CNVs) on these pathways. Lastly, in Aim 3 we analyze the effects of DISC1 disruption and SCZ-linked CNVs on proliferation and migration in vivo in the embryonic rodent brain via the complementary methods of in utero electroporation to knock down or overexpress genes and transplantation of human NPCs harboring these disruptions. Taken together, we aim to identify how the effects of these mutations converge to result in altered cortical circuitry and the onset o mental illness. Under this research plan, we take initial steps to compare how specific genetic disruptions with strong effect on risk for mental illness affect developmental signaling pathways and processes in human neuronal cells.