Gradients and the Control of Pattern Formation

梯度和图案形成的控制

• 批准号: 9982535
• 负责人: Stephen Small
• 金额: $ 35.6万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9982535&HistoricalAwards=false
• 关键词: Gradients; Control; Pattern; Formation

Recent experiments suggest that gradients of regulatory molecules areimportant for establishing the body plans of multicellular animals.However, little is known about the mechanisms whereby target genes respondto changes in the concentration of regulatory molecules. This applicationproposes to study these mechanisms in Drosophila, which is ideal for thispurpose because the early embryo is a syncytium of nuclei that do notpossess cytoplasmic membranes. This permits the study of transcriptionmechanisms directly, without complications from cell-cell signalingprocesses. The work will focus on four gap genes, hunchback, giant,Kruppel, and knirps, whose overlapping protein gradients form an integratedsystem that establishes striped patterns of gene expression in middleregions of the embryo. This work is driven by the hypothesis that thesegradients establish positions of gene expression borders by acting asconcentration-dependent repressors. For each gradient, the borders ofseveral target genes are set at different positions with respect to thesource. This suggests that each target gene responds to a differentconcentration threshold of repressive activity. To test this hypothesis,previously characterized enhancers and the yeast FLP-FRT recombinationsystem will be used to ectopically express different levels of each geneoutside its normal domain. These experiments will test whether expressionof a given gap gene is sufficient for a particular response, and identifypotential new target responses. The misexpression system will also be usedto dissect regions of the gap proteins that are required for repression.Initially, the focus will be on evolutionarily conserved domains that havebeen previously implicated in repression. Together these experiments willhelp clarify the genetic circuitry that controls the positioning andspacing of gene expression boundaries in the early embryo, and provideinsights into general mechanisms that control how different target genesrespond to different combinations and concentrations of regulatoryproteins. They will also provide a firm foundation for studies designed tounravel the mechanisms that change body plans during evolution.

最近的实验表明，调控分子的梯度对于建立多细胞动物的身体计划很重要。然而，我们对靶基因对调控分子浓度变化的反应机制知之甚少。这一应用建议在果蝇中研究这些机制，这是理想的，因为早期胚胎是细胞核合胞体，不具有细胞质膜。这允许直接研究转录机制，而没有细胞-细胞信号过程的并发症。这项工作将集中在四个间隙基因上，即驼背基因、巨人基因、克虏伯基因和尖刀基因，它们重叠的蛋白质梯度形成了一个完整的系统，在胚胎中部建立了基因表达的条纹模式。这项工作是由这样的假设驱动的，即这些梯度通过作为浓度依赖性抑制因子来建立基因表达边界的位置。对于每个梯度，几个目标基因的边界被设置在相对于源的不同位置。这表明每个靶基因对抑制活性的浓度阈值有不同的反应。为了验证这一假设，将使用先前表征的增强子和酵母FLP-FRT重组系统在其正常结构域外异位表达不同水平的每个基因。这些实验将测试是否表达一个给定的间隙基因是足够的一个特定的反应，并确定潜在的新的目标反应。错误表达系统还将用于解剖抑制所需的间隙蛋白区域。最初，重点将放在进化上保守的区域，这些区域以前与抑制有关。总之，这些实验将有助于阐明控制早期胚胎中基因表达边界的定位和间隔的遗传电路，并提供对控制不同靶基因如何对不同组合和调节蛋白浓度作出反应的一般机制的见解。它们还将为在进化过程中改变身体结构的机制的研究提供坚实的基础。