New functions of Pals1 as a signaling hub at cell-cell contacts

Pals1 作为细胞间接触信号枢纽的新功能

• 批准号: 414057425
• 负责人: Professor Dr. Michael Krahn, Ph.D.
• 金额: --
• 依托单位: Medizinische Klinik D: Allg. Innere Medizin und Notaufnahme sowie Nieren- und Hochdruckkrankheiten und Rheumatologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/414057425?language=en
• 关键词: New; functions; Pals1; signaling; hub

Cell-cell adhesion and the subsequent establishment of apical-basal polarity is a crucial prerequisite for the functionality of epithelia. By the asymmetric distribution of receptors, transporters and signalling molecules (e.g. protein complexes but also certain lipids), epithelial cells enable the selective uptake of nutrients and signals on either side of the cell. Moreover, specific cell-cell contacts, the Tight Junctions, are also crucial for the establishment of epithelial-specific permeability barriers. During the last years numerous studies reported close connections between cell-cell contact maturation and cell polarization on the one hand and signalling cascades regulating cell-differentiation, -growth and -proliferation on the other hand. Many of these connections seem to be highly conserved during evolution, e.g. from Drosophila to mammals. Pals1 (Stardust/Sdt in Drosophila) is a core component of the Crumbs complex and data from our and other groups suggest that Pals1/Sdt functions as a dynamic signalling hub at cell-cell contacts in epithelial cells, regulating cell proliferation, contact inhibition and cell differentiation. In this proposal we will investigate how the expression levels of Pals1/Sdt determine the fine-tuning between cell-cell contact formation and cell-cell contact-dependent gene expression by the modulation of intracellular signalling pathways. Thus one aim of this project is to elucidate how Pals1/Sdt protein stability is controlled during cell-cell contact maturation and how its degradation is regulated in de-differentiating cells. Second, we aim to identify the physical protein-protein interactions that mediate Pals1-dependent signalling and gene expression. Finally we will investigate how imbalanced Pals1-dependet cellular functions are linked to tumour progression and metastasis of tumour cells. Experimentally, these objectives will be addressed by using cultivated mammalian cells (MDCK cells) as in vitro system to characterize the Pals1-pedendent mRNA profile as well as the Pals1-interactome, considering different growth conditions (high versus low density, or 2D versus 3D cultures). The outcome of these experiments will be completed and validated by structure-function studies in the Drosophila system. Moreover, we aim to compare these data with that of colorectal cancer cell lines and investigate colonic organoids to elucidate the contribution of Pals1-dependent cellular functions for tumorigenesis and metastasis of tumour cells. We believe that our experiments will contribute to a deeper understanding of Pals1-dependent cell-cell contact signalling pathways as well as of how a dysfunction of these processes contribute to the progression of tumours.

细胞-细胞黏附和随后建立的尖-基两极是上皮细胞功能的关键前提。通过受体、转运体和信号分子(如蛋白质复合体和某些脂质)的不对称分布，上皮细胞能够选择性地摄取细胞两侧的营养物质和信号。此外，特定的细胞-细胞接触，即紧密连接，对于建立上皮特异性渗透屏障也是至关重要的。在过去的几年里，许多研究报道了细胞接触成熟和细胞极化与调节细胞分化、生长和增殖的信号级联信号之间的密切联系。其中许多连接在进化过程中似乎是高度保守的，例如从果蝇到哺乳动物。Pals1(果蝇中的Stardust/SDT)是Crumbs复合体的核心成分，来自我们和其他团队的数据表明，Pals1/SDT在上皮细胞中作为细胞-细胞接触的动态信号枢纽，调节细胞增殖、接触抑制和细胞分化。在这个提案中，我们将研究Pals1/SDT的表达水平如何通过调节细胞内信号通路来决定细胞-细胞接触形成和细胞-细胞接触依赖基因表达之间的微调。因此，这个项目的目的之一是阐明Pals1/SDT蛋白在细胞-细胞接触成熟过程中的稳定性是如何控制的，以及它的降解是如何在去分化的细胞中被调控的。其次，我们的目标是确定介导Pals1依赖的信号和基因表达的物理蛋白质-蛋白质相互作用。最后，我们将研究不平衡的Pals1依赖的细胞功能如何与肿瘤的进展和肿瘤细胞的转移有关。在实验上，这些目标将通过使用培养的哺乳动物细胞(MDCK细胞)作为体外系统来表征Pals1-Peendent mRNA图谱以及Pals1-Interactome，考虑不同的生长条件(高密度与低密度，或2D与3D培养)。这些实验的结果将通过果蝇系统的结构-功能研究来完成和验证。此外，我们的目标是将这些数据与结直肠癌细胞系的数据进行比较，并研究结肠类器官，以阐明依赖Pals1的细胞功能在肿瘤细胞的发生和转移中的作用。我们相信，我们的实验将有助于更深入地了解Pals1依赖的细胞-细胞接触信号通路，以及这些过程的功能障碍如何促进肿瘤的进展。