Modeling gene regulatory mechanisms contributing to the evolution of the human cerebral cortex

项目摘要 人类大脑皮层的巨大扩张使我们有别于我们的灵长类亲属，而这一皮质 扩展是人类独特的高级认知的基础。无数的发展创新， 例如，皮质前体细胞的增殖增加，促成了这种皮质生长。最终，这些 发展创新源于人类谱系中的基因变化，这改变了分子和 支撑发展的手机程序。了解特定的基因调控网络 了解人类皮质发育和皮质大小对于了解糖尿病的病因至关重要。 神经发育障碍，通常表现为认知障碍。努力识别人类特有的 基因变化揭示了人类加速区(HARs)，这是高度保守的调控 具有较高的人类特有序列变化率的元件。越来越多的证据表明 HARs在皮质发育和进化中的作用。特别是，Har HACNS205具有(I)以人为本 与黑猩猩相比，脑器官的可及性和增强剂活性的证据；(Ii)基本的 在人类神经干细胞增殖中的作用；以及(Iii)胎儿人类皮质中已知的靶基因Brn2，a 调节皮质生成的转录因子，在皮质祖细胞中有人类偏向的表达 相对于黑猩猩。Brn2是自闭症的易感基因，其靶基因表现为自闭症易感基因的富集性。 此外，临床研究还将Brn2突变与全球发育迟缓和认知障碍联系起来。 Brn2最近也被认为与人类大脑皮层的进化有关。过度表达研究表明Brn2是 对于指定神经前体细胞的特性、神经发生的时间和产生特定的 神经元亚型。然而，HACNS205在人类皮质发育中的作用尚不清楚；此外， Brn2在早期皮质发育中的作用尚未见报道。这项提案的目标是解决这些问题 该领域的空白，通过使用人性化的小鼠模型来研究HACNS205如何影响Brn2的表达水平 和Brn2转录因子结合，以及这些主要分子效应如何塑造基因表达， 分子网络、祖细胞行为和皮质发育中关键事件的时间。具体来说， 我将对胚胎皮质发育进行全基因组、表观遗传学和单细胞转录分析。 这些结果随后将被用来对这些动物发育中的皮质进行有针对性的表型分析 小鼠，以确定HACNS205驱动的祖细胞行为、神经发生和最终皮质的变化 形态学。申请者的长期目标是研究大脑进化中新细胞类型的出现。这 奖学金将帮助申请者发展生物信息学和进化、监管和 功能基因组学将极大地支持她在这一领域的成功，补充她目前的 神经生物学和皮质发育方面的专业知识。

Project Summary The vast expansion of the human cerebral cortex distinguishes us from our primate relatives, and this cortical expansion is the foundation of uniquely human higher-order cognition. Numerous developmental innovations, such as increased proliferation of cortical progenitor cells, contributed to this cortical growth. Ultimately, these developmental innovations arose from genetic changes in the human lineage, which altered the molecular and cellular programs underpinning development. Understanding the gene regulatory networks that specifically inform human cortical development and cortical size is crucial for understanding the etiology of neurodevelopmental disorders, which often present with cognitive impairment. Efforts to identify human-specific genetic changes have revealed Human Accelerated Regions (HARs), which are highly conserved regulatory elements that exhibit a high rate of human-specific sequence change. A growing body of evidence implicates HARs in cortical development and evolution. In particular, the HAR HACNS205 has (i) human-biased accessibility in cerebral organoids, compared to chimpanzee, and evidence of enhancer activity; (ii) an essential role in human neural stem cell proliferation; and (iii) a known target gene in the fetal human cortex, BRN2, a transcription factor that regulates corticogenesis and has human-biased expression in cortical progenitor cells relative to chimp. BRN2 is an autism risk gene, and its target genes display enrichment for autism risk genes. In addition, clinical work has linked BRN2 mutations to global developmental delay and cognitive impairment. BRN2 has also recently been implicated in human cortical evolution. Overexpression studies indicate BRN2 is important for designating neural progenitor cell identity, the timing of neurogenesis, and the production of specific neuronal subtypes. However, the role of HACNS205 in human cortical development is not clear; moreover, the role of BRN2 in early cortical development has not been reported. The goal of this proposal is to address these gaps in the field, by using a humanized mouse model to study how HACNS205 impacts BRN2 expression levels and BRN2 transcription factor binding, and how these primary molecular effects shape gene expression, molecular networks, progenitor cell behavior, and the timing of key events in cortical development. Specifically, I will employ genome-wide epigenetic and single-cell transcriptomic analyses of embryonic cortical development. These results will then be leveraged to perform targeted phenotypic analysis of the developing cortex in these mice, to identify HACNS205-driven shifts in progenitor cell behavior, neurogenesis, and ultimately cortical morphology. The applicant’s long-term goal is to study the emergence of novel cell types in brain evolution. This fellowship will aid the applicant in developing the expertise in bioinformatics and evolutionary, regulatory, and functional genomics that will greatly bolster her success in this line of research, complementing her current expertise in neurobiology and cortical development.