Neurobiological Mechanism of 15q11-13 Duplication Autism Spectrum Disorder

描述（由申请人提供）：本项目的长期目标是比较和对比由改变Ube 3a基因剂量产生的神经元mRNA表达和电路功能的缺陷，这些缺陷可能是具有母体15 q11 -13重复的自闭症谱系障碍（ASD）和Angelman综合征（AS）的行为表型的基础。来自15 q11 -13 ASD和AS患者的细胞分别具有过量和缺乏的E3泛素连接酶Ube 3a。Ube 3a基因是脑内唯一从母体等位基因中选择性表达的基因。大多数从母亲那里继承了15 q11 -13重复的儿童会患上ASD，遗传的拷贝越多，损伤就越严重。最近，我们建立了增加Ube 3a基因剂量单独重建自闭症相关的行为缺陷的三联体小鼠。相比之下，Angelman综合征（AS）是由儿童遗传了母亲的Ube 3a基因突变引起的。重要的是，Ube 3a还作为核受体共激活剂，独立于连接酶活性调节基因表达。因此，我们假设过量的Ube 3a（15 q dup模型）在细胞核中起作用，扰乱特定神经元基因和编码蛋白的正常表达，改变电路功能，从而产生自闭症相关的行为缺陷。逻辑推论是，核Ube 3a的缺陷可能会改变基因表达，从而改变电路功能，并通过相同但相反的机制产生Angelman相关的行为缺陷。因为大脑的回路是为感官信息和定量运动反应的定量评估而设计的，所以当控制回路功能的许多分子的数量改变时，它们可能会导致行为的分级变化。我们提出Ube 3a通过剂量依赖性调节神经元基因表达来做到这一点。这种分子量的变化可能是行为障碍如ASD的内在异质性的基础。这项R 01资助的具体目标如下：（1和2）确定Ube 3a基因剂量是否导致ASD（过量Ube 3a）和AS（3）鉴定由Ube 3a的过量或不足定量调节的皮质神经元mRNA;和（4）鉴定由Ube 3a的过量和不足定量诱导的皮质环路功能障碍。我们的方法包括一种新的核靶向Ube 3a转基因，神经元细胞类型特异性表达的Ube 3a，全基因组分析的成绩单，并确定共识Ube 3a基因启动子结合位点。切片电生理学和神经元形态学将检查整体和细胞类型特异性变化以及Ube 3a基因剂量的核靶向变化对活脑切片中皮质回路功能的影响。这项分析将有助于我们在这两种截然不同的人类神经系统疾病中从基因到电路再到行为的努力。该项目促进了该机构的使命，即通过遗传模型进一步深入了解ASD和AS中涉及的神经元细胞、电路和基因。新的分子见解和遗传工具将促进这些终身行为的治疗方法的发展。 残疾。

DESCRIPTION (provided by applicant): The long-term objective of this project is to compare and contrast the defects in neuronal mRNA expression and circuit functions produced by altered Ube3a gene dosage that may underlie the behavioral phenotypes of Autism Spectrum Disorder (ASD) with maternal 15q11-13 duplication and Angelman's Syndrome (AS). Cells from 15q11-13 ASD and AS patients have excess and deficient E3 ubiquitin ligase, Ube3a, respectively. Ube3a is the sole gene expressed selectively from the maternal allele in brain. The majority of children who inherit 15q11-13 duplications from their mothers develop ASD and the more copies inherited, the more severe the impairment. Recently, we established that increasing Ube3a gene dosage alone reconstitutes the triad of autism-related behavioral deficits in mice. Angelman's Syndrome (AS), by contrast, results when children inherit maternal Ube3a gene mutations. Importantly, Ube3a also acts as a nuclear receptor co-activator regulating gene expression independent of ligase activity. Thus we hypothesized that excess Ube3a (15q dup model) acts in the nucleus to perturb the normal expression of specific neuronal genes and encoded proteins to alter circuit function and thereby generate autism-related behavioral deficits. The logical corollary is that deficiencies of nuclear Ube3a may alter gene expression to change circuit function and produce Angelman-related behavioral deficits through the same, but opposite mechanisms. Because the brain's circuitries are designed for quantitative assessment of sensory information and quantitative motor responses, it is likely that many molecules controlling circuit functions can cause graded changes in behavior when their quantities are altered. We propose Ube3a do so through a dose-dependent regulation of neuronal gene expression. Such molecular quantity variations likely underlie the intrinsic heterogeneity of behavioral disorders like ASD. The specific aims of this R01 grant follow: (1 and 2) determine if Ube3a gene dosage causes ASD (excess Ube3a) and AS (deficient Ube3a) related behavioral deficits through its actions within the nucleus; (3) identify the cortical neuron mRNAs quantitatively regulated by excesses or deficiencies of Ube3a; and (4) identify the cortical circui dysfunctions quantitatively induced by excesses and deficiencies of Ube3a. Our methods include a novel nuclear-targeted Ube3a transgene, a neuron cell-type specific expression of Ube3a, genome wide analysis of transcripts, and identification of consensus Ube3a-gene promoter binding sites. Slice electrophysiology and neuronal morphology will examine the effects of global and cell-type specific changes and nuclear targeted changes of Ube3a gene dosage on cortical circuit function in living brain slices. This analysis will facilitate our effors to bridge from genes to circuits to behavior in the two contrasting human neurological diseases. The project promotes the agency's mission to further a deeper understanding of the neuronal cells, circuits, and genes involved in ASD and AS via genetic models. The novel molecular insights and genetic tools will facilitate development of treatments for these life-long behavioral disabilities.