Understanding Brain Development Through the Lens of Metabolism

人类大脑皮层是一个复杂的结构，由不同的区域组成，具有专门的功能和连接模式。单细胞测序的最新进展已经开始阐明存在于小鼠和人脑中的额外的细胞类型多样性，在其他相应的兴奋细胞类型之间存在显著的转录区域差异。了解这些细胞类型是如何出现的，对于了解神经发育障碍可能是如何发生的，以及更好地对人类皮质细胞类型进行建模，以及理解干细胞疗法如何以特定区域的方式最好地发展是至关重要的。此外，许多细胞类型的暂态群体仅在发育过程中存在，并可能掌握着关于什么信号决定人类大脑皮层区域身份的关键线索。初步数据表明，前体细胞的少量差异会导致兴奋性神经元的更大差异。此外，这些区域特异性基因的初步特征表明脂类代谢和运输基因的丰富。脂肪小体是中枢神经系统的一个方面，在人类中高度进化和复杂，占中枢神经系统质量的一半。此外，某些代谢物已被鉴定为调节干细胞的维持和分化，并且在一些神经发育障碍中发生突变或失调。已知脂质对突触通讯或神经肽信号转导很重要，但到目前为止，脂类在决定细胞类型或祖细胞命运中的作用尚不清楚。我们在人类皮质发育方面的初步数据表明，存在令人难以置信的脂类多样性，以及某些类别脂类的细胞类型和区域特异性。因此，该项目的具体目标首先寻求使用转录和脂组学方法(K99阶段)描述跨多个区域和年龄的发育中的人类大脑皮层(K99阶段)，同时也优化技术以生成介于脂质和转录身份之间的“Rosetta Stone”(K99+R00阶段)。利用我们的初步数据，将调查候选转录因子和脂代谢基因在调节区域认同方面的作用。通过对祖细胞进行基因操作，我们将评估对神经元合成区域特性的影响。结合这些实验将能够分层确定新陈代谢和转录调节如何相互作用来决定皮质祖细胞的细胞命运。总之，这些描述性数据集和机械实验将提高我们对人类皮质祖细胞对细胞类型及其规格的理解，并提供更多关于发育障碍可能如何出现以及最终如何针对它们的洞察，可能是通过治疗干预的代谢轴。由此产生的独特的数据集将作为多模式细胞类型分析和后续机制研究的资源，不仅为我们的研究小组，而且为整个社区。

The human cerebral cortex is a complex structure comprised of distinct areas with specialized functions and connectivity patterns. Recent advances in single-cell sequencing have started to illuminate additional cell type diversity that exists in both mouse and human brains, with significant transcriptional areal differences between otherwise corresponding excitatory cell types. Understanding how these cell types emerge is essential to understanding how neurodevelopmental disorders may arise, as well as to better model human cortical cell types and to understand how stem cell therapies may best be developed in an area specific manner. Moreover, a number of transient populations of cell types exist solely during development and may hold crucial clues as to what signals determine areal identity in the human cortex. Preliminary data suggests that a small number of differences in progenitor cells cascade into larger differences in excitatory neurons. Moreover, initial characterizations of these area specific genes indicate an enrichment of lipid metabolism and transport genes. The lipidome is an aspect of the central nervous system that is highly evolved and complex in humans and comprises half of the central nervous system mass. Additionally, certain metabolites have been characterized to regulate stem cell maintenance and differentiation, and in a number of neurodevelopmental disorders are mutated or dysregulated. Lipids are known to be important for synaptic communication or neuropeptide signaling, but the role of lipids in defining cell type or progenitor fate is heretofore undescribed. Our preliminary data in human cortical development suggests there is incredible lipid diversity, as well as cell type and area specificity of certain classes of lipids. Thus, the specific aims of this project first seek to characterize the developing human cerebral cortex across multiple regions and ages using both transcriptomic and lipidomic approaches (K99 phase), while also optimizing technologies to generate a “Rosetta Stone” between lipid and transcriptional identity (K99 + R00 phase). Utilizing our preliminary data, a list of candidate transcription factors and lipid metabolism genes will be surveyed for a role in regulating areal identity. By genetically manipulating progenitor cells, we will assess the impact upon resultant area identity of neurons. Integrating these experiments will enable a hierarchical determination of how metabolism and transcriptional regulation cross-talk to determine cell fate decisions in cortical progenitors. Together, these descriptive datasets and mechanistic experiments will improve our understanding of cell types and their specification from progenitors in the human cortex, and offer additional insight into how developmental disorders may emerge and eventually how they may be targeted, potentially through a metabolic axis of therapeutic intervention. The unique datasets generated through this will serve as a resource for multimodal cell type analysis and follow up mechanistic study not only for our research group, but also for the community at large.