Post-transcriptional regulation of signaling systems during neural crest induction

项目概要/摘要 神经嵴是一种多能胚胎干细胞群，可产生大部分颅面神经细胞。 骨骼包括软骨和骨。神经嵴发育失调会导致多种颅面畸形 异常和出生缺陷。因此，详细阐述指导神经嵴形成的过程对于 与这种细胞类型相关的病理学的诊断和治疗。神经嵴细胞是由 神经板边界信号系统的联合作用，神经板边界是邻近神经板的祖细胞条纹 神经板。 Wnt 和 FGF 的相反形态发生素梯度是祖细胞决定的核心 这两种命运之间的关系：神经嵴的诱导需要高水平的 Wnt 和低水平的 FGF， 而高水平的 FGF 则驱动细胞走向神经命运。最近的研究强调了以下要求： 神经板边界诱导信号的精确组合，但我们的了解仍然很肤浅 了解如何微调 FGF 和 Wnt 水平以启动神经嵴遗传程序。一监管 可能在早期胚胎期间信号通路活性的滴答中发挥核心作用的机制 发育是 microRNA (miRNA) 介导的基因沉默。4 有趣的是，我们发现 通过敲低禽类胚胎中 Dicer 的 miRNA 途径导致神经板区域扩张 神经嵴细胞的消耗。此外，我们最近采用小 RNA 测序来鉴定 miRNA 在神经嵴中富集。我们对该数据集的初步分析表明，神经嵴 miRNA (i) 受经典 Wnt 信号传导调节，并且 (ii) 它们靶向 FGF 的重要成分 信号通路。因此，我们假设 Wnt 信号传导激活一组 miRNA 的表达 抑制 FGF 信号传导以促进神经嵴形成。为了测试我们的模型，我们将使用基因组、功能、 和生化方法来定义神经嵴中 Wnt 激活的 miRNA 的调节和功能。 我们的结果将确定一种新颖的转录后机制，该机制作用于信号系统下游 调节细胞状态转变并将揭示早期颅面发育的分子控制。

PROJECT SUMMARY/ABSTRACT The neural crest is a multipotent embryonic stem cell population that gives rise to most of the craniofacial skeleton including cartilage and bone. Misregulation of neural crest development results in several craniofacial anomalies and birth defects. Thus, elaboration of the processes guiding neural crest formation is imperative for diagnosis and treatment of pathologies associated with this cell type. Neural crest cells are induced by the combined action of signaling systems at the neural plate border, a stripe of progenitor cells adjacent to the neural plate. Opposing morphogen gradients of Wnts and FGFs are central for progenitor cells to decide between these two fates: induction of the neural crest requires high levels of Wnts and low levels of FGFs, while high levels of FGFs drive cells towards a neural fate. Recent studies highlight the requirement of a precise combination of signals for neural plate border induction, but we still have a superficial understanding for how levels of FGF and Wnt are fine-tuned to jumpstart the neural crest genetic program. A regulatory mechanism that may play a central role in tittering the activity of signaling pathways during early embryonic development is microRNA (miRNA) mediated gene silencing.4 Intriguingly, we found that inactivation of the miRNA pathway via knockdown of Dicer in avian embryos results in expansion of the neural plate territory at the expense of neural crest cells. Furthermore, we have recently employed small RNA-sequencing to identify miRNAs enriched in the neural crest. Our preliminary analysis of this dataset has indicated that neural crest miRNAs (i) are regulated by canonical Wnt signaling and that (ii) they target important components of the FGF signaling pathway. Accordingly, we hypothesize that Wnt signaling activates the expression of a set of miRNAs that inhibit FGF signaling to promote neural crest formation. To test our model, we will use genomic, functional, and biochemical approaches to define the regulation and function of Wnt-activated miRNAs in the neural crest. Our results will identify a novel post-transcriptional mechanism that acts downstream of signaling systems to regulate cell state transitions and will shed light on the molecular control of early craniofacial development.