Post-transcriptional regulation of signaling systems during neural crest induction

项目摘要/摘要 神经脊是一个多潜能的胚胎干细胞群体，它产生了大部分的颅面 骨骼，包括软骨和骨骼。神经脊发育的失调导致几个颅面 畸形和先天缺陷。因此，阐述引导神经隆起形成的过程对于 诊断和治疗与这种细胞类型相关的病理。神经脊细胞是由神经营养因子诱导的 在神经板边缘的信号系统的联合作用，一条邻近于 神经板。WNTs和FGFs的相反形态梯度是祖细胞决定的中心 在这两种命运之间：神经脊的诱导需要高水平的WNT和低水平的FGFs， 而高水平的FGFs则将细胞推向神经末期。最近的研究强调了一种要求 信号的精确组合用于神经板边界诱导，但我们仍有粗浅的认识 关于如何微调成纤维细胞生长因子和Wnt的水平，以启动神经脊遗传程序。A监管机构 在早期胚胎中可能在滴定信号通路活性方面发挥核心作用的机制 发育是微RNA(MiRNA)介导的基因沉默。4有趣的是，我们发现失活的 在禽类胚胎中，通过敲除DICER的miRNA途径导致神经板区域的扩大 神经脊细胞的代价。此外，我们最近还采用了小RNA测序技术来鉴定 富含在神经脊的miRNAs。我们对这个数据集的初步分析表明，神经峰 MiRNAs(I)受规范的Wnt信号调节，(Ii)它们靶向成纤维细胞生长因子的重要成分 信号通路。因此，我们假设Wnt信号激活了一组miRNAs的表达 抑制成纤维细胞生长因子信号以促进神经脊的形成。为了测试我们的模型，我们将使用基因组、功能、 以及生物化学方法，以确定Wnt激活的miRNAs在神经嵴中的调节和功能。 我们的结果将确定一种新的转录后机制，它作用于信号系统的下游，从而 调节细胞状态转换，并将有助于阐明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.