Characterizing enhancers regulating transcription factor expression for cell-type specification across neurodevelopment

项目摘要/摘要 超级增强子(Se)是基因组DNA的扩展区域，由多个假定的增强子组成 这有助于在发育过程中形成动态的基因表达模式。这一点在 神经发生是因为许多必需的转录因子具有复杂的发育阶段和细胞类型 中枢神经系统的特定表达模式。在发育中的视网膜中，Vsx2表达于 所有视网膜前体细胞，并维持在分化的双极神经元和Müler神经胶质细胞中。基因突变 Vsx2基因导致人类和小鼠小眼球，因为它是视网膜祖细胞所必需的 扩散。由于这种严重的早期发育表型，很难阐明Vsx2的作用 在双极神经元和Müler神经胶质细胞分化中。 Victoria Honnell发现，单个SE控制着这种复杂而动态的表达模式 老鼠。在视网膜发育的早期，一个区域的缺失会破坏视网膜祖细胞的增殖。这个 另一个区域的缺失对视网膜祖细胞的增殖没有影响，反而会导致完整的 双极神经元的丧失。这一原型SE可以作为解剖复杂基因表达的模型 发育过程中神经性转录因子的模式。此外，它还提供了一个独特的机会 在发育的特定阶段改变不同细胞类型中单个转录因子的表达。这 提供了对传统基因敲除小鼠无法实现的功能的更深入理解 接近了。 在这项拟议的研究的F99阶段，维多利亚将检查人类Vsx2 SE的模块化 视网膜器官模型。这将使该领域了解不同的增强子区域如何影响视网膜 人类发育模型中的细胞类型规格。在这项拟议研究的K00阶段，维多利亚 将研究控制大脑中基因表达的其他SE的模块化。她将描述 这些SE区域的环状相互作用和表观遗传格局，以了解它们如何影响基因 大脑发育的多个阶段的表达，以及这些机制中的异常是如何起作用的 神经发育障碍和神经退行性疾病。 这项拟议的工作将产生一种创新的方法来解开基因的早期和晚期效应 具有复杂的表达模式，并提供了对增强子的表观遗传格局的理解 影响神经源性转录因子的表达。最终，这将使该领域了解到 导致中枢神经系统紊乱和疾病的疾病。

Project Summary/Abstract Super-enhancers (SEs) are expansive regions of genomic DNA comprised of multiple putative enhancers that contribute to dynamic gene expression patterns during development. This is particularly important in neurogenesis because many essential transcription factors have complex developmental stage– and cell–type specific expression patterns across the central nervous system. In the developing retina, Vsx2 is expressed in all retinal progenitor cells and is maintained in differentiated bipolar neurons and Müller glia. Mutations in the Vsx2 gene cause microphthalmia in humans and mice because it is required for retinal progenitor cell proliferation. Due to this severe early developmental phenotype, it has been difficult to elucidate the role of Vsx2 in bipolar neuron and Müller glia differentiation. Victoria Honnell has found that a single SE controls this complex and dynamic pattern of expression in mice. The deletion of one region disrupts retinal progenitor cell proliferation in early retinal development. The deletion of another region has no effect on retinal progenitor cell proliferation but instead leads to a complete loss of bipolar neurons. This prototypical SE may serve as a model for dissecting the complex gene expression patterns for neurogenic transcription factors during development. Moreover, it provides a unique opportunity to alter expression of individual transcription factors in distinct cell types at specific stages of development. This provides a deeper understanding of function that cannot be achieved with traditional gene knockout mouse approaches. In the F99-phase of this proposed research, Victoria will examine the modularity of the Vsx2 SE in human retinal organoid models. This will inform the field’s understanding of how distinct enhancer regions affect retinal cell-type specification in a model of human development. In the K00-phase of this proposed research, Victoria will examine the modularity of other SEs controlling gene expression in the brain. She will characterize the looping interactions and epigenetic landscape of these SE regions to understand how they influence gene expression at multiple stages across brain development, and how aberrations in these mechanisms contribute to neurodevelopmental disorders and neurodegenerative disease. This proposed work will yield an innovative approach to uncouple the early and late stage effects of genes with complex expression patterns and provide an understanding of how the epigenetic landscape of enhancers affect the expression of neurogenic transcription factors. Ultimately, this will inform the field’s understanding of enhanceropathies that contribute to disorders and diseases of the central nervous system.