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 连接处 (AJ) 和桥粒 (DSM) 在单层上皮中，这些连接处沿着顶端定位。 细胞侧膜末端，形成顶端连接复合体 (AJC)，但 不是 TJ，也存在于基底外侧质膜上，但它们的尺寸要小得多。 连接组织的不对称是单层上皮的一个独特的结构特征。 由一组保守的极性蛋白控制这是我们在本提案中要解决的主要问题。 是：两个极性蛋白，基底外侧蛋白 Scrib 和顶端蛋白 Par3，如何与蛋白质互连 调节 AJC 中细胞与细胞连接的定位。 我们最近发表的结果表明 Scrib 如何保持简单上皮细胞的“基底外侧同一性” 膜，多年来一直难以捉摸的机制，我们发现Scrib的这个功能是基于的。 对磷酸酶 PP1 (PP1) 和 Rho/Rac 鸟嘌呤核苷酸交换因子这两种酶的调节， GEF-H1 的结果表明，Scrib 将 PP1 保持在非活性状态，并通过以下方式将其释放为活性形式： 与其他极性蛋白 Llgl、Dlg 和 Band 4.1 的相互作用 DSM 组装的极性装置是一种 ARM 蛋白，plakophilin 3 (Pkp3)。 蛋白质存储在 TJ 周围的“休眠”库中，该库是在顶端极性蛋白的控制下建立的 Par3 从该池中释放的 Pkp3 的活性形式，使用以下机制驱动 DSM 的形成： 与进化相关连接的组装机制完全不同，AJ。 提供一些证据表明涉及类似的 Pkp 依赖性连接组装机制 形成以前未被识别的 AJ 亚型，我们在此将其称为 Pkp4 依赖性 AJ。 前几年取得的进展使我们能够提出这项提案，其中包括对以下方面的调查： (i) Scrib 如何调节 PP1 以及该通路的效应子是什么；(ii) Pkp3 如何调节粘附； 桥粒钙粘蛋白的活性以及极性系统如何调节其 DSM 组装活性； (iii) Pkp4 如何控制 AJ 特定子集组装中经典钙粘蛋白的粘附活性。 将为开发调节粘合剂和阻隔性能的试剂铺平道路 上皮组织。