Context-specific regulation of Wnt/beta-catenin target genes

一般研究问题：生物学中最重要的问题之一是我们的身体是如何形成的。胚胎中的许多细胞相互沟通，首先安排总体的身体计划，然后调节专门细胞的形成，以构建我们的器官。这些胚胎细胞通过分子细胞间的信号传导机制相互沟通。这一过程在出生后持续进行，器官得到修复，组织通过这种特化细胞的持续形成而再生。与胚胎中相同的细胞间信号通路调节着成人的这一过程。因此，信号机制的缺陷不仅会导致婴儿出生缺陷，还会导致成人疾病，如癌症。具体研究问题：Wnt信号是我们最重要的分子细胞间信号传导机制之一。我们已经很好地理解了线性分子Wnt信号级联，它的功能是打开或关闭在我们的功能器官中构建专门细胞所需的特定基因。然而，我们还不了解Wnt信号如何在不同的组织和器官中找到正确的基因来打开或关闭。我们显然需要揭示这些重要的机制，这些机制允许Wnt信号在胚胎发育和不同干细胞中重复发挥作用，同时可靠地打开或关闭每种类型细胞中的正确基因集。实验系统：我们最近利用了最先进的分子分析方案，使我们能够以全面的方式识别特定细胞群中由Wnt信号打开的所有基因。我们已经在一个可访问的实验系统中建立了这些方法，我们已经知道，与稍老的细胞相比，Wnt信号调节早期胚胎细胞的方式在短时间内发生了巨大变化。通过这些新方法，我们现在已经发现Wnt信号确实在后期细胞中开启了非常不同的基因，而不是我们已经知道的早期细胞中的少数基因。具体目标:1。既然我们现在已经非常了解晚期细胞中开启的一组基因，我们现在想要与早期细胞中开启的一组同样经过充分分析的基因进行适当的比较。2. 因为我们大致知道哪一组分子在开关打开或关闭时触摸开关，我们现在想研究不同的单个分子是否在不同的组织中触摸不同的开关，这可能会允许不同的基因组在早期被打开，而不是在后期的细胞中。当我们知道早期和晚期细胞中的特定开关以及早期和晚期细胞中接触这些开关的分子时，我们将研究这些分子被引导到正确开关的分子机制。结果和益处：我们的实验模型系统现在允许我们解决这些科学问题。然而，我们的实验结果不仅与这个实验模型系统相关。同样的Wnt信号级联也控制着成人的干细胞，例如疾病中的癌细胞。因此，广泛的科学领域将受益于我们关于不同组织中Wnt信号如何开启或关闭不同特定基因的研究结果。我们的实验还将开发分子工具和实验方法，这将证明对其他人有用，因为他们需要识别特定细胞群中通过某种分子途径打开的所有基因；或者一组特定的分子是如何发现、触摸和转动开关来激活这些基因的。

GENERAL RESEARCH QUESTION: One of the most important questions in biology asks how our body is built. The many cells in the embryo communicate with each other, first to arrange the general body plan and then to regulate formation of specialised cells to build our organs. These embryonic cells communicate with each other using molecular cell-to-cell signalling mechanisms. This process persists after birth when organs are repaired and tissues regenerated by continued formation of such specialised cells from resident adult stem cells. The same cell-to-cell signalling pathways as in the embryo regulate this process in the adult. Defects in signalling mechanisms consequently do not only lead to birth defects in babies but also to diseases in adults, such as cancer.SPECIFIC RESEARCH QUESTION: Wnt signalling is one of our most important molecular cell-to-cell signalling mechanisms. We already have a good understanding of the linear molecular Wnt signalling cascade, which functions to switch on or off specific genes that are needed to build specialised cells in our functional organs. However, we do not yet understand how Wnt signalling manages to find the correct genes to switch on or off in different tissues and organs. We clearly need to uncover these important mechanisms that allow Wnt signalling to function repeatedly during embryonic development and in different stem cells, while nonetheless reliably switching on or off the correct set of genes in each of these types of cells. EXPERIMENTAL SYSTEM: We have recently taken advantage of state-of-the-art molecular analysis protocols, which allow us to identify in a comprehensive manner all the genes that are switched on by Wnt signalling in a particular group of cells. We have established these methods in an accessible experimental system where we knew already about a dramatic change happening in a short time in the way Wnt signalling regulates early embryonic cells compared to slightly older cells. With these new methods we have now uncovered that Wnt signalling indeed switches on very different genes in later cells than the few we already knew about in early cells. SPECIFIC OBJECTIVES:1. Since we are now getting to know very well the set of genes switched on in later cells, we now want to carry out a proper comparison with an equally well analysed set of genes switched on in earlier cells. 2. Because we know generally which group of molecules touch switches as they are turned on or off, we now want to investigate whether different individual molecules touch different switches in different tissues, which may then allow different sets of genes to be switched on in early as compared to later cells.3. When we know the particular switches in early and in later cells and the molecules touching these switches in early and later cells, we will investigate the molecular mechanisms by which these molecules are guided to the correct switches. OUTCOMES AND BENEFITS: Our experimental model system allows us now to address these scientific questions. However, the findings from our experiments are going to be relevant not just for this experimental model system. The same Wnt signalling cascade also controls stem cells in the adult and for instance cancer cells in disease. A wide range of scientific fields will therefore benefit from our results about how different specific genes can be switched on or off by Wnt signalling in different tissues.Our experiments will also develop molecular tools and experimental approaches that will prove useful to others as they need to identify all the genes that are switched on by a certain molecular pathway in a particular group of cells; or how a specific group of molecules finds, touches and turns switches to activate these genes.