Patterning of Drosphila Embryos by the Dorsal-dependent Gene Network

描述(由申请人提供)：基因表达的阈值输出对于构建所有后生动物的模式非常重要。在这个后基因组时代，发育生物学领域的核心挑战之一是确定大量基因是如何差异表达的，以形成胚胎的模式，以及这些基因随后如何控制特定组织的分化。研究发育的全基因组方法通常会产生许多基因清单，这些基因被预测在调节生物学方面发挥作用。我们建议利用基因组数据来研究果蝇发育的转录调控，并将这一系统中发现的机制与人类联系起来。具体地说，我们感兴趣的是果蝇胚胎的背腹图案是如何受背部依赖的形态原梯度控制的。通过基因芯片分析，我们发现约50个基因受背部调控，并沿背腹轴在不同的结构域中差异表达。已鉴定的几个基因编码转录因子，这些转录因子可能与背部一起发挥作用，控制基因沿背腹轴的表达模式。我们关于背部依赖的靶基因表达的初步结果也提出了一些关于基因表达阈值输出的问题。特别是，背部靶基因的表达如何在空间上限制在背腹轴上的不同区域，以及在微阵列筛选中确定的转录因子是否与背部一起起到控制图案形成的作用？我们提出了两个具体的目标来解决这些问题：(1)通过增强子分析寻找与背部一起发挥功能的转录因子(使用我们已经确定的顺式调控基序对表达很重要)，以及(2)表征两个假定的转录因子的功能，我们认为这两个转录因子有助于胚胎的模式形成(Neu2，通过我们的微阵列研究确定，以及Wek，一个在基因筛查中发现的母性表达基因)。对这些转录因子在不同结构域上影响差异基因表达的机制进行表征，将为调控Dy形态原梯度的基因表达提供普遍适用的见解。这些研究还可能对REL转录因子的转录调控提供总体上的见解，因此有可能对NFkappaB调控的过程提供深远的影响，包括免疫反应、癌症和过敏性炎症。

DESCRIPTION (provided by applicant): Threshold outputs of gene expression are important for patterning all metazoa. One of the central challenges in the field of developmental biology in this post-genomics era is to determine how large numbers of genes are differentially expressed to pattern the embryo and how these genes subsequently control differentiation of specialized tissues. Whole-genome approaches to studying development typically generate many lists of genes that are predicted to function in regulating biology. We propose to utilize genomic data to study transcriptional regulation of development in Drosophila and relate the mechanisms uncovered in this system to humans. Specifically, we are interested in how dorsoventral patterning of the Drosophila embryo is controlled by the Dorsal-dependent morphogen gradient. By microarray analysis, we have found that ~50 genes are transcriptionally regulated by Dorsal and are differentially expressed along the dorsoventral axis in distinct domains. Several of the identified genes encode transcription factors that may function together with Dorsal to control patterning of gene expression along the dorsoventral axis. Our initial results on Dorsal- dependent target gene expression also raise a number of questions regarding threshold outputs of gene expression. In particular, how is the expression of Dorsal target genes spatially restricted to distinct domains along the dorsoventral axis and do transcription factors that were identified in the microarray screen function together with Dorsal to control patterning? We have proposed two specific aims to address these questions: (1) to identify transcription factors that function together with Dorsal through enhancer analyses (using cis- regulatory motifs we have identified are important for expression), and (2) to characterize the function of two putative transcription factors which we propose contribute to patterning of the embryo (Neu2, identified by our microarray studies, and Wek, a maternally expressed gene identified in a genetic screen). Characterization of the mechanisms used by these transcription factors to affect differential gene expression n distinct domains will provide generally applicable insights into the regulation of gene expression controlled Dy morphogen gradients. These studies may also provide insights into transcriptional regulation by Rel transcription factors in general, and therefore have the potential to provide far-reaching implications into processes regulated by NFkappaB including the immune response, cancer, and allergic inflammation .