Analysis of Noelin, a Neural Crest Competence Factor

描述(由申请人提供)：脊椎动物的神经脊似乎 通过非神经性外胚层和 神经板，因此既需要诱导源(外胚层)，也需要 合格的接受组织(神经板)。早期表达的分子 神经板可能参与使组织“有能力”做出反应 神经峰诱导。通过筛选神经脊/管文库，我们已经 鉴定出一种分泌因子Noelin-1，它在未来的 鸟类神经板，可能在使神经管具有能力方面发挥作用 形成神经峰。Noelin-1mRNA预测一种带有信号肽的蛋白质， N-糖基化位点和一个与嗅觉有关的结构域；当 在青蛙卵母细胞中过表达。Noelin-1mRNA以分级模式表达 在封闭的神经管中，神经皱折中表达最高，而不是 在腹中线可检测到表达。拟议中的实验将 扩展初步发现以进一步表征Noelin-1在 早期胚胎发育。我们的工作前提是Noelin-1赋予 能在神经管细胞上形成神经脊。Noelin表示为 中间神经板与神经板相关的时间 对非神经性外胚层的诱导做出反应的能力。最近的工作来自 我们的实验室认为，WNTS可能是最初的神经脊诱导剂和 BMP可能在以后起作用，以维持/扩大新诱导的神经脊 人口。因此，诺林承诺将成为一个特别令人兴奋的因素，因为 对潜在的组织能力和生物学特性知之甚少 能力因素如何与诱导者相互作用。 我们假设：(1)Noelin-1使神经板具有反应能力 从表面外胚层发出的感应信号 共同受体；(2)背侧神经管神经脊标志物的维持 可能涉及Noelin加BMP或其他神经管信号的组合；以及 (3)Noelin表达受Sonic等腹侧神经管信号的抑制 刺猬。我们将通过分离Noelin结合伙伴来检验这些假设， 确定其功能需求并分析组织/细胞 调节其表达的相互作用。这项提议的目标是 进一步研究Noelin-1在分子和细胞中的功能 水平。具体的实验将：(1)确定分子的性质 与Noelin-1互动。(2)确定Noelin在传授中的作用 神经管细胞产生神经脊的能力。(3)生成和 鉴定Noelin-1缺失突变体的表型。(4)审查 Noelin-1表达的环境调控。

DESCRIPTION (provided by the applicant): The vertebrate neural crest appears to form via an inductive interaction between the non-neural ectoderm and the neural plate, thus requiring both a source of inducer (the ectoderm) and a competent receiving tissue (the neural plate). Molecules expressed in the early neural plate may be involved in rendering the tissue "competent" to respond to neural crest induction. By screening neural crest/tube libraries, we have identified a secreted factor, Noelin-1, which is expressed in the prospective avian neural plate and may play a role in making the neural tube competent to form neural crest. Noelin-1 mRNA predicts a protein with a signal peptide, N-glycosylation sites and an olfactomedin-related domain; it is secreted when over-expressed in frog oocytes. Noelin-1 mRNA is expressed in a graded pattern in the closing neural tube, with highest expression in the neural folds and no detectable expression at the ventral midline. The proposed experiments will extend the preliminary findings to further characterize the role of Noelin-1 in early embryonic development. Our working premise is that Noelin-1 bestows competence onto neural tube cells to form neural crest. Noelin is expressed in the intermediate neural plate at a time that correlates with the neural plate's ability to respond to induction by the non-neural ectoderm. Recent work from our laboratory suggests that Wnts may be the initial neural crest inducers and that BMPs may function later to maintain/expand newly-induced neural crest population. Thus, Noelin promises to be a particularly exciting factor since little is known about biological properties underlying tissue competence and how competence factors interact with inducers. We hypothesize that: (1) Noelin-1 renders the neural plate competent to respond to an inductive signal from the surface ectoderm by functioning as a co-receptor; (2) maintenance of neural crest markers in the dorsal neural tube may involve a combination of Noelin plus BMP or other neural tube signals; and (3) Noelin expression is repressed by ventral neural tube signals like Sonic hedgehog. We will test these hypotheses by isolating Noelin binding partners, determining its functional requirements and analyzing the tissue/cellular interactions that mediate its expression. The goal of this proposal is to further characterize the function of Noelin-1 at the molecular and cellular level. Specific experiments will: (1) Determine the nature of molecules that interact with Noelin-1. (2) Determine the function of Noelin in imparting competence to neural tube cells to generate neural crest. (3) Generate and characterize the phenotype of Noelin-1 null mutant. (4) Examine the environmental regulation of Noelin-1 expression.