Defining the mechanisms that remodel the multivalent domain structures of cell junctions during morphogenetic activities

在我的项目中，我将进一步了解细胞如何在形态发生过程中保持相互连接，其中连接复合体必须动态响应细胞形状变化和有丝分裂活动。这一过程的失败可能导致发育障碍和癌细胞转移。我推测，这种动态响应是基于连接复合物的结构与多价域，调节连接的细胞骨架。在本研究中，我将进一步研究连接相关蛋白Pyd和Cno在果蝇胚胎上皮组织中的作用。果蝇胚胎发育过程中胚带伸长和背侧闭合的过程提供了一个有用的工具来研究连接动力学，因为它们是由细胞插入，有丝分裂和组织运动引起的高组织力定义的。在cno和pyd突变体胚胎中，组织破裂和细胞形状紊乱尤其见于组织应力升高的区域。因此，这些蛋白质似乎通过能够将连接复合物连接到细胞骨架来为粘附连接提供鲁棒性。然而，它们在这一过程中的机制作用仍不清楚。我将通过详细检查突变表型来分析Pyd对连接稳健性的影响，并研究已知Pyd相互作用物在此过程中的作用。初步的数据可以证实在pyd突变体中，在胚带延伸的过程中，细胞形状受到了干扰，这可能是细胞插入和连接动力学受到干扰的结果。对固定和活标本的进一步研究将包括对细胞形状、细胞嵌入和连接动力学的详细描述和量化，这将有助于理解这些连接相关蛋白的功能。组织内的细胞是动态的，这一事实需要动态连接，以确保有丝分裂、细胞嵌入和细胞形状变化期间的完整性。因此，稳定的细胞-细胞连接应该一方面提供刚度，但另一方面对变化做出灵活的响应。因此，我推测，连接复合物和它的连接到细胞骨架显示相互作用的蛋白质，提供了提供这两个要求的能力的子结构。一个潜在的亚结构的主要迹象是部分分离的连接相关蛋白臂，Cno和Baz在成熟的果蝇上皮。在研究期间，我将利用超分辨率显微镜进一步解剖果蝇胚胎和哺乳动物细胞中细胞连接的亚结构。在这两个系统中，将研究其成熟和维护过程中的连接动力学。此外，我将比较一个组织内表现出不同力f的连接的亚结构。e.与双细胞连接相比，三细胞连接具有更高的力。

In my project I will gain further understanding how cells remain attached to each other during morphogenetic processes in which the junctional complexes have to respond dynamically to cell shape changes and mitotic activity. A failure of this process can lead to developmental disorders and metastasis of cancer cells. I hypothesize that this dynamic response is based on the structure of the junctional complex with multivalent domains that regulate the connection of junctions to the cytoskeleton. In this study, I will further investigate the role of the junction-associated proteins Pyd and Cno in embryonal epithelial tissues of Drosophila melanogaster. The processes of germ band elongation and dorsal closure during Drosophila embryogenesis provide a useful tool to investigate junctional dynamics as they are defined by high tissue forces due to cell intercalation, mitosis and tissue movement. In cno and pyd mutant embryos, tissue rupture and perturbed cell shapes were especially observed at regions with elevated tissue stress. Thus, these proteins seem to provide robustness to adherens junctions by being able to connect the junctional complex to the cytoskeleton. However, their mechanistical role in this process remained unclear. I will analyze the effect of Pyd on junction robustness by detailed examination of mutant phenotypes and investigate the roles of known Pyd interactors in this process. Preliminary data could confirm perturbed cell shapes in pyd mutants during the process of germ band elongation that could be a result of perturbed cell intercalation and junction dynamics. Further investigation of fixed and live specimen will include detailed description and quantification of cell shapes, cell intercalation and junction dynamics which will help to understand the function of these junction-associated proteins.The fact that cells within a tissue are dynamic requires dynamic junctions which have to ensure integrity during mitosis, cell intercalation and cell shape changes. Thus, the stable cell-cell junction should on the one hand provide stiffness but on the other hand respond flexible on changes. Thus, I hypothesize that the junctional complex and its connection to the cytoskeleton display a substructure of interacting proteins that provide the ability to provide both requirements. Primary indication of a potential substructure is the partial segregation of the junction-associated proteins Arm, Cno and Baz in mature Drosophila epithelia. During my study, I will further dissect the substructure of cell junctions in Drosophila embryos and mammalian cells by super-resolution microscopy. In both systems will study junction dynamics during their maturation and maintenance. Furthermore, I will compare the substructures of junctions within one tissue that exhibit differential forces, f. e. tricellular junctions with higher forces versus bicellular junctions.