Genes and developmental signaling pathways in neuropsychiatric disorders

描述(申请人提供)：哺乳动物皮质的发育是一个复杂的过程，需要精确协调神经元的增殖、迁移、轴突生长和突触形成。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。在过去的十年里，几个与神经发育有关的基因被认为与SCZ及相关疾病有关。其中一些基因作用于典型的WNT或Reelin(RELN)信号通路，这两个信号通路分别在增殖和迁移中发挥核心作用。传统上认为，这些通路在神经元发育的不同时间独立发挥作用。然而，这些途径之间存在着共同的分子因子，如DISC1。我们的主要假设是WNT和RELN途径相互作用，调节增殖和迁移之间的发育开关。此外，我们假设，在这些通路之间共享的基因的破坏，如DISC1，会导致精神障碍风险的增加。我们的实验室已经建立了同基因的人类诱导多能干细胞(IPSCs)，这种干细胞在DISC1基因座附近有靶向突变，该位点靠近与重大精神障碍有关的chr(1；11)平衡易位。我们将使用这些线路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，观察到的表型将在带有CHR(1；11)易位的SCZ受试者的HiPSCs中进行检测。此外，为了检验分子和细胞表型是否延伸到DISC1中断之外，将对患有与精神疾病相关的CNV的SCZ患者的HiPSCs进行有限的分析。为了补充这些体外研究，将并行利用死后的人脑组织和啮齿动物模型来建立关键发现的体内相关性。在目标1中，我们研究了DISC1亚型在等基因和患者来源的野生型和突变系中的神经元分化表达。我们通过基因表达谱、形态计量学分析和电生理分析来分析这些神经元的成熟。在目标2中，我们研究了WNT和RELN信号转导通路，并比较了DISC1中断和SCZ连锁拷贝数变异体(CNV)对这些通路的影响。最后，在目标3中，我们分析了DISC1基因中断和SCZ连接的CNV对胚胎啮齿动物脑内增殖和迁移的影响，通过宫内电穿孔基因敲除或过表达基因和移植含有这些中断的人神经干细胞的互补方法。综上所述，我们的目标是确定这些突变的影响是如何聚合在一起，导致皮质回路改变和精神疾病的发病。在这项研究计划下，我们采取初步步骤比较特定的基因中断如何影响人类神经细胞的发育信号通路和过程，这些基因中断对精神疾病的风险有很强的影响。

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.