Mechanisms by Which Macrocephaly Underlies Autism Spectrum Disorder

项目摘要/摘要 自闭症谱系障碍(Asd)是一种高度遗传性、异质性的神经发育障碍。 在美国，每53名儿童中就有一名受到影响。调节社会认知和语言的前额叶皮质奇怪的是 在有严重症状的ASD患者中，至少有15%的患者放大。巨头畸形(大脑)是 由皮质祖细胞过度增殖引起，来自ASD患者的祖细胞显示 过度扩散。然而，前额叶巨头畸形本身对 ASD的病理生理学机制尚不清楚。 ASPM(异常纺锤体样小头畸形)是一种神经发育基因，它决定了 皮质大小，并可能在巨头畸形，以及在ASD中发挥作用。ASPM控制细胞增殖，其 功能丧失突变是遗传性小头畸形(小脑)最常见的原因，尤其是 前额叶皮质严重受损。重要的是，它在皮质前体细胞中表达，而不是在神经元中表达。最近， ASPM中的从头变异与ASD有关。我们的初步数据显示，其中一个变种 增加培养细胞中的ASPM蛋白水平，提示功能获得突变。此外，我们 产生了带有功能获得突变的ASPM敲入小鼠，表现出过度的神经再生，围产期 巨头畸形，以及表现为ASD样症状的异常社会行为。 我们的长期目标是了解大脑皮质发育异常的机制 是ASD功能异常的基础。我们的中心假设是过度的胚胎神经发生， 这会导致巨头症，足以通过干扰细胞信号和 出生后大脑中的成分。为了检验这一假设，我们将利用与ASD相关的功能增益 ASPM中的突变，并在三个特定目的中检测Aspm基因敲入小鼠。因此，我们将(目标1)调查 使用免疫染色的神经发育轨迹，(目标2)确定细胞成分和 使用单核RNA测序的信号传递，(目标3)Aspm敲入小鼠的社会认知行为。我们的 建议的研究具有重要意义，因为我们直接解决了大头畸形在ASD中的病理生理学作用。它 是创新的，因为我们分析了一种新的ASD小鼠模型，该模型在 使用各种最先进技术的神经发育基因ASPM。 一些症状严重的ASD患者会出现巨头畸形。然而，在多大程度上 大头畸形本身对ASD的影响尚不清楚。我们的新型ASPM敲入小鼠携带与ASD相关的 突变并表现为围产期巨头畸形伴异常的社会行为。探索失调的细胞类型 而Aspm基因敲入小鼠的信号通路可能为ASD提供新的治疗干预措施。

PROJECT SUMMARY/ABSTRACT Autism spectrum disorder (ASD) is a highly heritable, heterogeneous neurodevelopmental disorder affecting 1 in 53 children in the US. The prefrontal cortex, which mediates social cognition and language, is oddly enlarged in at least 15% of patients with ASD who suffer from severe symptoms. Macrocephaly (large brain) is caused by excessive proliferation of cortical progenitors, and progenitors derived from ASD patients show excessive proliferation. However, the extent to which prefrontal macrocephaly itself contributes to the pathophysiology of ASD is unclear. ASPM (abnormal spindle-like microcephaly-associated) is a neurodevelopmental gene that determines cortical size, and may play a role in macrocephaly, as well as in ASD. ASPM controls cell proliferation, and its loss-of-function mutations are the most common cause of genetic microcephaly (small brain) that are particularly severe in the prefrontal cortex. Importantly, it is expressed in cortical progenitors but not in neurons. Recently, de novo variants in ASPM have been associated with ASD. Our preliminary data show that one such variant increases ASPM protein levels in cultured cells, suggesting gain-of-function mutation. Furthermore, we generated Aspm knock-in mice with the gain-of-function mutation, which show excessive neurogenesis, perinatal macrocephaly, and abnormal social behavior recapitulating ASD-like symptoms. Our long-term goal is to understand the mechanisms by which abnormal cerebral cortical development underlies functional abnormalities in ASD. Our central hypothesis is that excessive embryonic neurogenesis, which results in macrocephaly, is sufficient to elicit some ASD-like behaviors by disturbing cell signaling and composition in the postnatal brain. To test the hypothesis, we will leverage the ASD-associated gain-of-function mutation in ASPM, and examine Aspm knock-in mice in three Specific Aims. Thus, we will (Aim 1) investigate the neurodevelopmental trajectory using immunostaining, (Aim 2) determine changes in cell composition and signaling using single-nucleus RNA sequencing, (Aim 3) social cognitive behaviors in Aspm knock-in mice. Our proposed research is significant as we directly address the pathophysiological role of macrocephaly in ASD. It is innovative as we analyze a novel ASD mouse model with a gain-of-function mutation in the neurodevelopmental gene ASPM using diverse, state-of-the-art techniques. Macrocephaly is observed in some ASD patients with severe symptoms. However, the extent to which macrocephaly itself contributes to ASD is unclear. Our novel Aspm knock-in mice carry an ASD-associated mutation and display perinatal macrocephaly with abnormal social behavior. Exploring dysregulated cell types and signaling pathways in Aspm knock-in mice may provide novel therapeutic interventions for ASD.