The Role of NMD in Cortical Neural Progenitor Cells

项目摘要 无义介导的mRNA衰变（NMD）关键因子的突变，包括Upf2、Upf3a、Upf3b和Smg6， 富含各种神经发育疾病。除了通过降解来确保转录质量之外， 异常转录物与提前终止密码子，NMD调节选择性mRNA的稳定性， 转录本丰度。NMD是否以及如何影响大脑发育仍然难以捉摸。我们的长期 目的是了解国家导弹防御系统管制在复杂的动态过程中的功能作用， 神经发生及其失调如何导致神经发育障碍。我们确定 通过选择性基因切除Upf 2和体内NMD对神经发育的需求 操纵NMD的其他因素。我们的初步数据表明，UPF2在神经干和 祖细胞导致小头畸形。UPF2缺失特异性地影响细胞周期和谱系进展， 放射状胶质细胞（RGC），发育中的新皮质中的主要神经祖细胞。我们将联合收割机 边缘分子细胞核糖基因组学方法，小鼠遗传学和发育神经生物学， NMD调控神经发生的机制。我们提出了三个独立而又相互关联的目标， 研究小头畸形表型潜在的可能变量。在目标1中，我们将确定细胞 定性和定量研究NMD基因敲除小鼠RGCs的周期行为， 监管机制。在目标2中，我们将确定RGCs的谱系进展以及由此产生的 NMD敲除小鼠每时间单位的神经元输出。通过表征这些分子细胞缺陷，我们 也旨在为RGC谱系转换的转录组调控提供机制见解。NMD可以 调节细胞命运，或者独立于细胞周期控制，或者作为影响细胞周期的结果。在 目的3，我们将测试这两个假设，并利用我们的结果重新检查细胞之间的关系， 周期和细胞命运。成功完成这些研究将提供基本的见解如何选择性 mRNA的稳定性是哺乳动物大脑中高度调节的皮质神经发生过程的基础。的 拟议的研究也将阐明一些基本问题，如细胞周期的控制，细胞命运， 以及它们在神经发育过程中的关系

PROJECT SUMMARY Mutations in key factors of nonsense-mediated mRNA decay (NMD), including Upf2, Upf3a, Upf3b, and Smg6, are enriched in various neurodevelopmental diseases. In additional to ensuring transcript quality by degrading aberrant transcripts with a premature stop codon, NMD modulates stability of selective mRNAs to fine-tune transcript abundance. Whether and how NMD influences brain development remains elusive. Our long-term objective is to understand the functional role of NMD regulation for the complicated and dynamic process of neurogenesis and how its mis-regulation leads to neurodevelopmental disorders. We determine the requirement of NMD for neural development through selective genetic ablation of Upf2 and in vivo manipulation of other NMD factors. Our preliminary data show that deletion of UPF2 in neural stem and progenitors results in microcephaly. UPF2 loss specifically affects the cell cycle and lineage progression of radial glia cells (RGCs), the major neural progenitor cells in the developing neocortex. We will combine cutting edge molecular cellular ribogenomics approaches, mouse genetics, and developmental neurobiology to dissect the mechanisms of NMD regulating neurogenesis. We propose three independent and interrelated aims to investigate possible variables underlying the microcephaly phenotype. In Aim 1, we will determine the cell cycle behaviors of RGCs in NMD knockout mice qualitatively and quantitatively and unveil the underlying regulatory mechanisms. In Aim 2, we will determine the lineage progression of RGCs and the resulting neuronal outputs per time unit in NMD knockout mice. By characterizing these molecular cellular defects, we also aim to provide mechanistic insights to transcriptomic regulation of RGC’s lineage transitions. NMD may regulate cell fates either independent of cell cycle controls or as the consequence of affecting the cell cycle. In Aim 3, we will test these two hypotheses and leverage our results to reexamine the relationship between cell cycle and cell fate. Successful completion of these studies will provide fundamental insights into how selective mRNA stability underlies the highly regulated cortical neurogenesis process in the mammalian brain. The proposed studies will also shed light on some fundamental questions about the control of cell cycle, cell fate, and their relationship during neural development.