Coupling intercellular adhesion, polarity and mechanical signals at epidermal junctions

表皮连接处的细胞间粘附、极性和机械信号的耦合

• 批准号: 273723548
• 负责人: Professorin Dr. Sandra Iden
• 金额: --
• 依托单位: Lehrstuhl für Zell- und Entwicklungsbiologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/273723548?language=en
• 关键词: Coupling; intercellular; adhesion; polarity; mechanical

Cell polarization is essential for proper development, tissue homeostasis and regeneration. Studies in lower organisms identified important regulators of cell and tissue architecture. Polarity proteins of the Par3-aPKC-Par6 complex mediate diverse cellular processes and couple control of cell shape to signalling pathways regulating growth, cell fate and differentiation. Yet, how these conserved polarity regulators contribute to mammalian tissue function and disease is much less clear. The skin is a tensile tissue constantly exposed to mechanical stress. Whether and how polarity proteins drive polarization in stratified epithelia like the skin epidermis and how they contribute to chemical and mechanical signalling in this tissue is largely unknown. Our recent work revealed important roles of Par3 and aPKCl in skin cancer, with junction-localized but not cytoplasmic Par3 promoting growth, survival and ultimately tumorigenesis. We further showed that Par3 inactivation in the mouse epidermis results in epidermal barrier defects, stem cell decline and premature differentiation. Moreover, Par3 controls P-cadherin surface expression, thereby regulating epidermal cell-cell interactions. Within the SPP1782 we combined different biophysical methods with cell biological, genetic and proteinbiochemical approaches to reveal unexpected mechanisms through which junctional Par3 couples mechanical signals at intercellular adhesions with cellular responses to ensure epidermal homeostasis and barrier integrity. We deciphered that Par3 promotes Rho-driven actomyosin contractility to foster intrinsic force generation at cell-cell contacts, important to maintain the tight junctional barrier. Moreover, our data indicate that polarity proteins mediate dynamic junction remodelling in response to external mechanical cues. Intriguingly, correcting myosin activation was also sufficient to rescue mitotic defects and ectopic differentiation upon Par3 loss, unravelling a central role of actomyosin regulation in polarity protein-dependent epidermal self-renewal and differentiation. Having established the importance of junctional Par3 for keratinocyte mechanics, key efforts in the second funding period will aim to unravel further molecular links between mechanical and polarity signalling at intercellular adhesions that mediate cytoskeletal and biochemical responses. We will use gain- and loss-of-function approaches, proteomics, biophysical and imaging methods to examine the relevance of three classes of adhesion molecules that are deregulated following Par3 loss. Moreover, we will investigate mechanochemical effector pathways downstream of junctional polarity proteins and ask how polarity networks transmit mechanical cues to the cell’s interior to instruct strain adaptation. Together, this SPP1782 project will provide molecular insight into the coupling of intercellular junctions, cell polarity and force transmission in an important barrier-forming epithelium.

细胞极化是正常发育、组织稳态和再生的必要条件。对低等生物的研究发现了细胞和组织结构的重要调节因子。Par3-aPKC-Par6复合物的极性蛋白介导多种细胞过程，并将细胞形状控制与调节生长、细胞命运和分化的信号通路相结合。然而，这些保守的极性调节因子如何影响哺乳动物的组织功能和疾病尚不清楚。皮肤是一种经常暴露在机械应力下的拉伸组织。极性蛋白是否以及如何驱动分层上皮（如皮肤表皮）中的极化，以及它们如何促进该组织中的化学和机械信号传导，在很大程度上是未知的。我们最近的工作揭示了Par3和aPKCl在皮肤癌中的重要作用，连接定位的Par3而不是细胞质的Par3促进生长、生存和最终的肿瘤发生。我们进一步发现，Par3在小鼠表皮中的失活导致表皮屏障缺陷、干细胞衰退和过早分化。此外，Par3控制p -钙粘蛋白表面表达，从而调节表皮细胞-细胞相互作用。在SPP1782中，我们将不同的生物物理方法与细胞生物学、遗传学和蛋白质生化方法相结合，揭示了连接Par3在细胞间粘附时将机械信号与细胞反应耦合以确保表皮稳态和屏障完整性的意想不到的机制。我们发现Par3促进rho驱动的肌动球蛋白收缩，从而促进细胞-细胞接触产生内力，这对维持紧密的连接屏障很重要。此外，我们的数据表明极性蛋白介导响应外部机械信号的动态连接重塑。有趣的是，纠正肌球蛋白激活也足以在Par3缺失时挽救有丝分裂缺陷和异位分化，揭示了肌动球蛋白调节在极性蛋白依赖的表皮自我更新和分化中的核心作用。在确定了连接Par3对角化细胞力学的重要性之后，第二个资助期的重点工作将是进一步揭示介导细胞骨架和生化反应的细胞间粘附中机械和极性信号之间的分子联系。我们将使用功能获得和功能丧失方法、蛋白质组学、生物物理和成像方法来检查在Par3丢失后失去调控的三类粘附分子的相关性。此外，我们将研究连接极性蛋白下游的机械化学效应途径，并询问极性网络如何将机械信号传递到细胞内部以指导菌株适应。总之，SPP1782项目将提供细胞间连接耦合、细胞极性和重要屏障形成上皮中的力传递的分子洞察力。