The role of E-cadherin in regulating signalling pathways

新颖性、研究计划和短期目标-E-钙粘附素显示出广泛的生物学功能，在胚胎发育、成体细胞重新编程为胚胎干细胞样细胞和成体组织维持/动态平衡过程中至关重要。虽然到目前为止，大多数研究都集中在生长因子、细胞外信号、转录因子和细胞内信号通路如何调控E-钙粘蛋白的表达，但一个基本的问题是，动态的E-钙粘蛋白表达及其细胞内伙伴是否以及在多大程度上影响它们的调控因子，共同控制胚胎发育和成年细胞的动态平衡和功能。这将是我们研究计划的长期目标。这项拟议项目的短期目标(和假设)将确定E-钙粘蛋白和Rap1调节的E-钙粘蛋白循环的细胞内伙伴是否会不同地影响NF-kB、Wnt和AKT信号活性和成人细胞功能(图1)。我们最近的进展和与这一拟议研究项目相关的初步工作-我实验室的受训人员已经证明，E-钙粘素能够主动调节胚胎干细胞(干细胞2010和2015，摩尔细胞蛋白质组学2011等)中的Wnt信号。我们最近观察到，高成体细胞E-钙粘附素显著抑制NF-kB，而上调Wnt和Akt的活性；Wnt抑制不同地影响其他信号通路和干细胞相关蛋白的表达(初步数据)。短期目标--成人细胞、功能得失和多学科方法将用于三个目标。在目标1中，第一组受训者将确定E-钙粘附素的哪些细胞内伙伴(a-连环蛋白、β-连环蛋白和p120)影响核因子-kB、Wnt和AKT活性、干细胞相关基因/蛋白和细胞功能(增殖、凋亡、迁移和细胞周期)。在目标2中，第二组受训者将确定Rap1调节的E-钙粘蛋白循环影响三种信号活性的程度。在目标3中，受训者将确定一个信号的抑制或激活(使用基因过表达、siRNA/shRNA击倒和小分子激活剂/抑制剂)是否以依赖于E-钙粘素的细胞内伙伴的方式不同地影响其他两个途径和细胞功能。意义-作为我们研究计划的一部分，从这个拟议的项目中获得的知识将为E-钙粘蛋白和Rap1调节的E-钙粘蛋白循环的细胞内伙伴在调节对成年细胞功能至关重要的NF-kB、Wnt和Akt信号通路中的未知角色提供新的见解。这将对细胞生物学产生广泛的影响，并将为学员提供一个极好的平台，为他们在学术界或生物技术公司的职业生涯做准备。

Novelty, research program and short-term goal - E-cadherin exhibits broad biological functions and is crucial during embryonic development, reprogramming of adult cells to embryonic stem-like cells and adult tissue maintenance/homeostasis. While the majority of studies thus far focus on how growth factors, extracellular signals, transcriptional factors, and intracellular signaling pathways regulate E-cadherin expression, a fundamental question that has been largely overlooked and yet to be answered is whether and to what extent the dynamic E-cadherin expression and its intracellular partners, in turn, affect their regulators to co-control embryonic development and adult cell homeostasis and functions. This will be the long-term goal of our research program. The short-term goal of this proposed project (and hypothesis) will determine whether intracellular partners of E-cadherin and Rap1-regulated E-cadherin recycling differentially affect NF-kB, Wnt and AKT signaling activities and adult cell functions (Fig 1). Our recent progress and preliminary work related to this proposed research project - The trainees in my lab have demonstrated that E-cadherin is capable of actively regulating Wnt signaling in embryonic stem cells (Stem Cells 2010 and 2015, Mol Cell Proteomics 2011, etc.). We recently observed that E-cadherinhigh adult cells markedly inhibits NF-kB whereas upregulating Wnt and Akt activity; Wnt inhibition differentially affects other signaling pathways and the expression of stem cell-associated proteins (preliminary data). Short term objectives - Adult cells, gain- and loss-of-function and multidisciplinary approaches will be used in three aims. In Aim 1, group 1 trainees will determine which intracellular partners of E-cadherin (a-catenin, ß-catenin, and p120) affect NF-kB, Wnt, and AKT activities, stem cell-associated genes/proteins and cell functions (proliferation, apoptosis, migration and cell cycle). In Aim 2, group 2 trainees will determine the extent by which Rap1-regulated E-cadherin recycling affects three signaling activity. In Aim 3, trainees will determine whether inhibition or activation of one signaling (using gene overexpression, siRNA/shRNA knockdown, and small-molecule activators/inhibitors) differentially affects other two pathways and cell functions in an E-cadherin-intracellular partners-dependent manner. Significance - As part of our research program, knowledge gained from this proposed project will provide new insights into the currently unknown roles of intracellular partners of E-cadherin and Rap1-regulated E-cadherin cycling in the regulation of NF-kB, Wnt, and Akt signaling pathways that are crucial for adult cell functions. This will have broad impacts in cell biology, and will also offer an excellent platform for trainees to prepare their careers for academia or biotechnology companies.