Post-transcriptional regulation of signaling systems during neural crest induction

项目总结/摘要 神经嵴是一种多能胚胎干细胞群，它产生了大部分颅面神经。 包括软骨和骨的骨骼。神经嵴发育失调导致几种颅面畸形 畸形和出生缺陷。因此，详细阐述指导神经嵴形成的过程对于 诊断和治疗与该细胞类型相关的病理。神经嵴细胞是由 在神经板边缘的信号系统的联合作用下，邻近神经板边缘的祖细胞条带， 神经板相反的Wnt和FGF的形态梯度是祖细胞决定 在这两种命运之间：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会驱使细胞走向神经命运。最近的研究强调， 神经板边界诱导的信号的精确组合，但我们仍然有一个肤浅的理解 FGF和Wnt的水平是如何微调的，以启动神经嵴遗传程序。监管 在早期胚胎发育过程中， 4有趣的是，我们发现，在基因沉默过程中， 通过敲低禽类胚胎中Dicer的miRNA途径导致神经板区域的扩张， 神经嵴细胞的消耗。此外，我们最近采用小RNA测序来鉴定 miRNAs在神经嵴中富集。我们对该数据集的初步分析表明，神经嵴 miRNAs（i）受经典Wnt信号转导的调节，（ii）它们靶向FGF的重要组分， 信号通路因此，我们假设Wnt信号激活了一组miRNAs的表达， 其抑制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， 和生物化学方法来确定Wnt激活的miRNA在神经嵴中的调节和功能。 我们的研究结果将确定一种新的转录后机制，该机制作用于信号系统的下游， 调节细胞状态转换，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.