Intercellular junctions and cell polarity

细胞间连接和细胞极性

• 批准号: 10567642
• 负责人: Sergey M Troyanovsky
• 金额: $ 45.58万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-15 至 2026-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10567642
• 关键词: Actins; Address; Adherens Junction; Adhesions; Adhesives; Apical; Architecture; Autoimmune Diseases; Binding; Biology; Cadherins; Cell Polarity; Cell membrane; Cell-Cell Adhesion; Cells; Communication; Compensation; Complex; Cytoskeleton; Data; Defect; Desmosomes; Development; Disease; Dissection; Enzymes; Epithelial Cells; Epithelium; Evolution; Family; Genetic Diseases; Goals; Grant; Guanine Nucleotide Exchange Factors; Inflammatory; Integral Membrane Protein; Intercellular Junctions; Invertebrates; Investigation; Lateral; Link; Location; Mammalian Cell; Mammals; Mediating; Medicine; Membrane; Minor; Modification; Molecular; Names; Pathway interactions; Phosphoric Monoester Hydrolases; Positioning Attribute; Process; Property; Protein Family; Proteins; Publishing; Reagent; Regulation; Role; Rosaniline Dyes; Signal Pathway; Signal Transduction; Simple Epithelium; Site; Structure; System; Tight Junctions; Tissues; Work; alpha catenin; antagonist; basolateral membrane; cell assembly; cell type; cohesion; extracellular; link protein; plakophilins; protease-activated receptor 3; receptor; rho; spatiotemporal; targeted treatment

All epithelial cells are interconnected through three major types of junctions – Tight Junctions (TJs), Adherens Junctions (AJs), and Desmosomes (DSMs). In simple epithelia, these junctions are positioned along the apical end of the cell lateral membrane, where they form the Apical Junctional Complex (AJC). AJs and DSMs, but not TJs, are also present along the basolateral plasma membrane, where they are much smaller in size. This asymmetry of junction organization is a distinctive architectural feature of simple epithelia. Such asymmetry is controlled by a set of conserved polarity proteins. The main question that we set out to address in this proposal is: how are two polarity proteins, basolateral protein Scrib and apical protein Par3, interconnected with proteins regulating the positioning of the cell-cell junctions in AJC. Our recently published results suggested how Scrib maintains “basolateral identity” of simple epithelial cell membrane, the mechanism that has been elusive for many years. We found that this function of Scrib is based on regulation of two enzymes, phosphatase PP1 (PP1) and Rho/Rac Guanine Nucleotide Exchange Factor, GEF-H1. Our results suggest that Scrib holds PP1 in inactive state and releases it in an active form through interactions with other polarity proteins, Llgl, Dlg, and Band 4.1. We also show that a protein that links the polarity apparatus with DSM assembly is an ARM protein, plakophilin 3 (Pkp3). We provide evidence that this protein is stored around TJs in a “dormant” pool that is established under control of the apical polarity protein Par3. The active form of Pkp3, released from this pool, drives formation of DSMs using the mechanism that is radically distinct from the assembly mechanism of the evolutionary related junctions, AJs. Furthermore, we present some evidence suggesting that a similar Pkp-dependent mechanism of junction assembly is involved in formation of a previously unrecognized subtype of AJs, which we call here Pkp4-dependent AJs. The advances made in previous years allow us to come up with this proposal, which includes the investigation of: (i) how Scrib regulates PP1 and what are the effectors of this pathway; (ii) how Pkp3 regulates adhesion activity of desmosomal cadherins and how its DSM assembly activity is regulated by the polarity system; and (iii) how Pkp4 controls adhesion activity of classic cadherins in assembly of specific subset of AJs. This work will pave the way toward the development of reagents modulating the adhesive and barrier properties of epithelial tissues.

所有上皮细胞均通过三种主要类型的连接连接 - 紧密连接（TJ），粘附器 连接（AJS）和Desmosomes（DSM）。在简单的上皮中，这些连接位于顶端 细胞侧膜的末端，它们形成顶端连接络合物（AJC）。 AJ和DSM，但是 不是TJ，也存在于基底外侧质膜，它们的大小要小得多。这 连接组织的不对称性是简单上皮的独特建筑特征。这样的不对称是 由一组保守的极性蛋白控制。我们设定在此提案中解决的主要问题 IS：与蛋白质互连的两种极性蛋白，底型蛋白涂鸦和顶蛋白PAR3如何 调节细胞电池连接在AJC中的位置。 我们最近发表的结果表明，SCRIB如何保持简单上皮细胞的“基础身份” 膜，多年来难以捉摸的机制。我们发现SCRIB的这个功能是基于的 在调节两种酶，磷酸酶PP1（PP1）和Rho/RAC鸟嘌呤核苷酸交换因子中， GEF-H1。我们的结果表明，SCRIB将PP1保持在不活动状态，并以主动形式释放 与其他极性蛋白，LLGL，DLG和Band 4.1的相互作用。我们还表明，一种蛋白质可以联系 带有DSM组装的极性设备是一种手臂蛋白，plakophilin 3（PKP3）。我们提供证据表明这 蛋白质在TJ周围存储在“休眠”池中，该池在根尖极性蛋白的控制下建立 par3。从该池释放的PKP3的主动形式使用该机制驱动DSM的形成 与进化相关连接的组装机理截然不同。此外，我们 目前的一些证据表明，涉及相似的PKP依赖性机制 在形成以前未认可的AJ的亚型时，我们在这里称之为PKP4依赖性AJ。这 往年的进步使我们能够提出这项建议，其中包括： （i）SCRIB如何调节PP1以及该途径的影响； （ii）pkp3如何调节粘附 脱乳小蛋白的活性以及其DSM组装活性如何受极性系统调节；和 （iii）PKP4如何控制经典钙粘蛋白在AJS特定子集组装中的广告活动。这项工作 将为开发试剂的开发铺平道路，以调节 上皮组织。