Differential response to the Dpp morphogen

对 Dpp 形态发生素的差异反应

• 批准号: 6721508
• 负责人: CHRISTINE A RUSHLOW
• 金额: $ 24.21万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6721508
• 关键词: DNA footprinting; Drosophilidae; affinity chromatography; binding sites; biological signal transduction; cofactor; developmental genetics; early embryonic stage; gel mobility shift assay; gene expression; gene induction /repression; gene interaction; genetic promoter element; genetic screening; genetic transcription; immunoprecipitation; mass spectrometry; transcription factor; transforming growth factors; yeast two hybrid system

DESCRIPTION (provided by applicant): The TGF-beta family of signaling molecules directs a wide variety of cellular and developmental processes by ultimately controlling gene expression. They signal through Smad proteins that function as transcription factors. In some instances, TGF-betas act in concentration gradients as morphogens to determine different cell fates. Dpp in Drosophila functions in a dorsal-to-ventral gradient in the blastoderm embryo, and specifies different fates by differentially regulating downstream target genes. For example. Race, a high-level target. is restricted to the dorsal-most cells. pannier, an intermediate-level target. is expressed in a broader domain, while tolloid. a low-level target is expressed in the broadest domain. How do these target genes interpret the Dpp gradient? Our results indicate that a simple mechanism involving a linear response to the Smad gradient does not apply, but rather, a combinatorial mechanism with additional factors is involved. One such factor, Brinker, functions as a repressor of some Dpp target genes. Interestingly, low levels of Dpp repress brinker expression limiting it to the ventral region. Thus. Dpp acts indirectly by repressing brinker, but also acts directly to activate some targets. What is the molecular mechanism by which the different target genes interpret Dpp and Brinker inputs? Are the regulatory sequences of all target genes similar with respect to these sites? If so, they would read the level of Smads and Brinker in each nucleus along the DV axis and respond accordingly. Or are they different from one another, each having either Smad or Brinker sites, and/or other factor binding sites? To address this question, we will compare the minimal Dpp-response elements of the representative target genes Race, pannier, and tolloid. In addition, we will manipulate the elements, as well as test synthetic promoters with Smad and/or Brinker sites. We will address the question of how Smads might outcompete Brinker, either by competition for DNA binding or by an anti-repression mechanism involving protein interactions. We will also investigate how Dpp signaling leads to repression of brinker, particularly how Smads interact with the putative repressor, Schnurri. We will identify additional cofactors involved in Dpp target gene regulation by genetic and molecular screens. Our specific aims focus on the different target gene promoters and how Brinker and Smads, and other cofactors, interact with them to control and fine-tune their transcriptional responses. These results will enhance our knowledge of the molecular basis of morphogen function, a key concept in developmental biology.

描述（由申请人提供）：信号分子的TGF-beta家族 通过最终指导各种细胞和发育过程 控制基因表达。它们通过SMAD蛋白发出信号，该蛋白起作用 转录因子。在某些情况下，TGF-betas集中作用 梯度为形态剂，以确定不同的细胞命运。果蝇中的DPP 在胚胚胚中的背侧梯度中起作用，并且 通过差异调节下游靶基因来指定不同的命运。 例如。种族，一个高级目标。仅限于最多的背细胞。 Pannier，一个中级目标。在更广阔的领域中表达 Tolloid。低级目标在最广泛的域中表示。这些如何 靶基因解释DPP梯度？我们的结果表明一个简单的 涉及对SMAD梯度的线性响应的机制不适用于 相反，涉及具有其他因素的组合机制。一个这样的 因子，边缘，充当某些DPP靶基因的阻遏物。 有趣的是，低水平的DPP压抑边缘表达将其限制在 腹侧区域。因此。 DPP通过压抑边缘间接起作用，但也采取行动 直接激活某些目标。什么是分子机制 不同的靶基因解释了DPP和边界输入？是监管 与这些位点相似的所有靶基因的序列？如果是这样，他们 会读取沿DV轴和 相应地回应。还是它们彼此不同，每个都有 SMAD或边界站点和/或其他因素结合位点？解决这个问题 问题，我们将比较最小的DPP响应元素 代表性靶基因种族，Pannier和Tolloid。此外，我们将 用SMAD和/或操纵元素以及测试合成启动子 边界站点。我们将解决SMADS如何胜过的问题 边缘，无论是竞争DNA结合还是抗抑制 涉及蛋白质相互作用的机制。我们还将调查如何DPP 信号传导会导致抑制边缘，尤其是Smads如何与 推定的阻遏物Schnurri。我们将确定其他辅助因子 通过遗传和分子筛选参与DPP靶基因调节。我们的 具体目的专注于不同的靶基因启动子以及边缘和如何 SMAD和其他辅助因子与它们互动以控制和微调他们的 转录响应。这些结果将增强我们对 形态学功能的分子基础，这是发育生物学的关键概念。