Dissecting the epigenetic mechanisms of interneuron fate determination

项目总结/摘要 大脑皮层包含巨大的神经元多样性，在发育过程中变得一体化 一系列惊人的神经回路尽管包括所有新皮层细胞的少数，抑制性 GABA能中间神经元（IN）在认知和神经元的基础回路的稳定性中起重要作用。 高级大脑功能越来越明显的是，神经精神障碍不成比例地产生于 影响中间神经元发育的损伤，包括癫痫、自闭症、双相情感障碍和精神分裂症。 因此，表征控制IN命运的分子机制对于我们理解IN的能力至关重要。 健康和疾病中的大脑。IN出生于端脑腹侧，主要在内侧，尾侧和外侧。 外侧神经节隆起（MGE，CGE和LGE），并切向迁移，以达到其在 大脑皮层尽管它们的多样性，IN被分为四种不重叠的功能细胞类型：小白蛋白 (PV)、生长抑素（SST）、血管活性肠肽（VIP）和表达Reelin的皮质INS。然而， 关于控制生物多样性的建立和多样化的命运决定机制， 这些人口。研究这些问题的难度更大，IN是在胚胎中出生的，但只有 在出生后第二周获得其亚型特异性特征。基因命运图谱和 移植的努力表明，胚胎祖细胞优先产生的定义群体中， 成人大脑然而，神经节隆起增殖区内祖细胞的转录谱 发现同质程序，没有明确的证据表明命运分叉。鉴于表观遗传调控 在转录输出之前，这个建议旨在更好地理解转录过程中的机制， 祖细胞表观遗传地致力于它们的成熟命运（在目标1中阐述）。拟议的实验将 测试祖细胞通过活性染色质构型在表观遗传上引发的假设， 在细胞类型特异性转录程序激活之前的增强子位点。的重点 该提案是关于产生PV和SST细胞类型的MGE祖细胞。此外，该提案将审查 PV和SST细胞的特性在发育过程中如何通过Satb 1基因的表观遗传作用维持 （目标2）。为了实现这些目标，由用于检测的测定驱动的整合基因组分析被用于检测基因组的表达。 转座酶可及染色质（ATAC-seq）将用于构建调控区域的表观基因组图谱 驱动细胞命运的规范和成熟。这些信息将用于阐明发展 中间神经元从祖细胞到成熟细胞类型的轨迹。最终，这些信息将改善我们的 理解祖细胞分化成不同亚类的空间和时间控制， 可用于识别中间神经元发育的关键阶段。这项研究将发挥重要作用， 鉴定和治疗与细胞类型特异性中间神经元功能障碍相关的神经精神疾病。

PROJECT SUMMARY/ABSTRACT The cerebral cortex contains enormous neuronal diversity that during development become integrated into a startling array of neural circuits. Despite comprising the minority of all neocortical cells, Inhibitory GABAergic interneurons (INs) play an important role in the stability of the circuits underlying cognitive and higher-order brain function. it is becoming evident that neuropsychiatric disorders disproportionately arise from insults affecting interneuron development, including epilepsy, autism, bipolar disorder, and schizophrenia. Therefore, characterizing the molecular mechanisms that control IN fate is crucial for our ability to understand the brain in health and disease. INs are born in the ventral telencephalon, primarily in the medial, caudal, and lateral ganglionic eminences (MGE, CGE, and LGE) and migrate tangentially to reach their settling position in the cortex. Despite their diversity, INs are classified into four non-overlapping functional cell types: parvalbumin (PV), somatostatin (SST), vasoactive-intestinal peptide (VIP), and Reelin-expressing cortical INs. However, little is known about the mechanisms of fate determination that control the establishment and diversification of these populations. Compounding the difficulty of studying these questions, INs are born embryonically but only acquire their subtype specific character in the second postnatal week. Genetic fate mapping and transplantation efforts indicate that embryonic progenitors preferentially give rise to defined populations in the adult brain. Yet transcriptional profiling of progenitors within the proliferative zones of the ganglionic eminences found homogenous programs with no clear evidence of fate bifurcation. Given that epigenetic regulation precedes the transcriptional output, this proposal seeks to better understand the mechanisms by which progenitors epigenetically commit to their mature fate (addressed in Aim 1). The proposed experiments will test the hypothesis that progenitors are epigenetically primed through active chromatin configurations at enhancer sites that precede the activation of cell-type specific transcriptional program. The focus of this proposal is on MGE progenitors that give rise to PV and SST cell types. Additionally, this proposal will examine how PV and SST cell identities are maintained during development by the epigenetic role of the Satb1 gene (addressed in Aim 2). To accomplish these aims, an integrative genomic analysis driven by an assay for transposase accessible chromatin (ATAC-seq) will be used to build an epigenomic map of regulatory regions that drive cell fate specification and maturation. This information will be used to elucidate the developmental trajectories of interneurons from progenitors to mature cell types. Ultimately, this information will improve our understanding of the spatial and temporal control of progenitor differentiation into distinct subclasses, which can be used to identify critical stages on interneuron development. This study will play an important role in identifying and treating neuropsychiatric diseases associated with cell-type specific interneuron dysfunction.