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.

所有上皮细胞通过三种主要类型的连接相互连接-紧密连接（TJ）、粘附连接（Adherens）、粘附连接（Adherens）和粘附连接（Adherens）。 连接（AJs）和桥粒（DSM）。在单纯上皮中，这些连接沿着顶面 细胞侧膜的末端，在那里它们形成顶端连接复合体（AJC）。AJ和DSM，但是 不是TJ，也沿着基底外侧质膜存在，在那里它们的尺寸小得多。这 连接组织的不对称性是简单上皮的独特结构特征。这种不对称性是 由一组保守的极性蛋白控制。我们在这份提案中要解决的主要问题是， 两种极性蛋白，基底外侧蛋白Scrib和顶端蛋白Par3，是如何与蛋白质相互连接的？ 调节AJC中细胞-细胞连接的定位。 我们最近发表的结果表明，Scrib如何维持简单上皮细胞的"基底外侧身份"， 膜，多年来一直难以捉摸的机制。我们发现Scrib的这个功能是基于 调节两种酶，磷酸酶PP1（PP1）和Rho/Rac鸟嘌呤核苷酸交换因子， GEF-H1。我们的研究结果表明，Scrib保持PP1处于非活性状态，并通过激活释放PP1。 与其他极性蛋白Llgl、Dlg和条带4.1的相互作用。我们还表明，一种蛋白质，连接 具有DSM组装的极性装置是ARM蛋白，斑嗜蛋白3（Pkp3）。我们提供的证据表明， 蛋白质储存在TJ周围的"休眠"池中，该池在顶端极性蛋白的控制下建立 第3段。从该池释放的Pkp3的活性形式使用以下机制驱动DSM的形成： 从根本上不同于进化相关的接头，AJs的组装机制。而且我们 提出了一些证据表明，一个类似的Pkp依赖机制的连接组装参与 形成了一种以前未被认识的AJs亚型，我们在这里称之为Pkp4依赖性AJs。的 前几年取得的进展使我们能够提出这一建议，其中包括调查： (i)Scrib如何调节PP1以及该途径的效应物是什么;（ii）Pkp3如何调节粘附 桥粒钙粘蛋白的活性及其DSM组装活性如何受极性系统调节;以及 (iii)Pkp4在特定AJs亚群组装中如何控制经典钙粘蛋白的粘附活性。这项工作 将为开发调节粘合剂和屏障性能的试剂铺平道路 上皮组织