Role of cell adhesion in organizing membrane growth.

细胞粘附在组织膜生长中的作用。

• 批准号: 8544475
• 负责人: Charles A Yeaman
• 金额: $ 27.69万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8544475
• 关键词: 3-Dimensional; Adherens Junction; Apical; Binding; Biochemical; Biogenesis; Biological Assay; Cell Adhesion; Cell Line; Cell membrane; Cell surface; Cell to Cell Adhesion Signaling Pathway; Cell-Cell Adhesion; Cells; Cellular Structures; Characteristics; Cilia; Complex; Cues; Cytoskeleton; Defect; Desmosomes; Development; Diabetes Mellitus; Disease; Dissociation; E-Cadherin; Epithelial; Epithelial Cells; Epithelium; Event; Exocytosis; Failure; Foundations; Goals; Golgi Apparatus; Growth; Guanosine Triphosphate Phosphohydrolases; Human; Individual; Intercellular Junctions; Intracellular Transport; Iron Metabolism Disorders; Knockout Mice; Knowledge; Laboratories; Lateral; Lead; Link; Malignant Neoplasms; Mediating; Membrane; Membrane Protein Traffic; Membrane Proteins; Metabolic Diseases; Modeling; Molecular; Monitor; Morphology; Mutagenesis; Mutate; Pathway interactions; Polycystic Kidney Diseases; Process; Property; Protein Isoforms; Proteins; RNA Interference; Recruitment Activity; Regulation; Regulation of Exocytosis; Renal function; Research; Role; SNAP receptor; Secretory Vesicles; Series; Signal Pathway; Signal Transduction; Site; Sorting - Cell Movement; Specificity; Structure; Surface; Testing; Thinking; Tight Junctions; Transport Vesicles; Variant; Vesicle; Work; base; basolateral membrane; cell type; extracellular; human disease; hypercholesterolemia; in vivo; insight; protein complex; protein protein interaction; rab GTP-Binding Proteins; receptor; syntaxin; syntaxin binding protein 1; trafficking

DESCRIPTION (provided by applicant): Spatial regulation of exocytosis is essential for establishing and maintaining cell surface polarity, a property vital to the correct function of epithelia. Failure to properly sort and deliver specific plasma membrane proteins to the correct surface of epithelial cells is a common feature of human metabolic diseases and cancers. Despite much progress in understanding the molecular mechanisms of protein sorting, major questions persist about how post-Golgi transport vesicles ferry apical and basolateral cargo to the correct site of fusion with the plasma membrane. The long-term goal of our research is to understand how environmental spatial cues, such as cell-cell adhesion, signal to the cytoskeleton and secretory apparatus to organize polarized trafficking pathways in epithelial cells. Based upon results of preliminary studies, a working hypothesis has been developed. Our central hypothesis is that Ral GTPases are activated upon initiation of E-cadherin-mediated cell adhesion, and that they regulate Exocyst functions in a spatio-temporal manner during the formation of specialized membrane domains-including the apical junctional complex, desmosomes and primary cilia. Our working model is that Ral GTPases regulate different steps in Exocyst-dependent trafficking, through sequential interactions with the Sec5 and Exo84 subunits. These interactions, in turn, drive an association/dissociation cycle between the Exocyst and "accessory factors" that either target Exocyst complexes to different subcellular sites or otherwise prepare them for specific functions at those sites. Finally, we propose that at least two different Exocyst-related complexes are recruited to nascent sites of intercellular contact, and subsequently move apart to facilitate the development of different types of intercellular junctions. The specific aims of this study are: 1) to investigate the function of Ral-Exocyst complexes in modulating epithelial polarization; 2) to determine how Sec6-Munc18 interactions control polarized exocytosis; and 3) to define how Sec6 is targeted to the AJC and determine whether multiple Exocyst-related complexes have distinct functions in intercellular junction formation. Collectively, the studies we propose in this application seek to uncover details of a mechanism that links an extracellular event, namely cell-cell adhesion, to activation of a signaling pathway that promotes polarized membrane trafficking during the establishment of epithelial polarity. Given that the molecules on which we will focus-specifically the Exocyst and Ral GTPases-are conserved across metazoans, we believe that studying how they collaborate to establish and maintain distinct junctional complexes in epithelial cells (e.g. the AJCs and desmosomes) will give us important insight into mechanisms that regulate the assembly of plasma membrane protein complexes in many other cell types. Thus, the significance of this work is that it will guide our thinking when considering therapies for a variety of human diseases in which intracellular transport and the assembly of membrane proteins is impaired.

描述（由申请人提供）：胞吐作用的空间调节对于建立和维持细胞表面极性至关重要，细胞表面极性对于上皮细胞的正确功能至关重要。未能正确分类并将特定质膜蛋白递送至上皮细胞的正确表面是人类代谢疾病和癌症的共同特征。尽管在理解蛋白质分选的分子机制方面取得了很大进展，但关于后高尔基体运输囊泡如何将顶端和基底外侧货物运送到与质膜融合的正确位点的主要问题仍然存在。我们研究的长期目标是了解环境空间线索（例如细胞间粘附）如何向细胞骨架和分泌装置发出信号，以组织上皮细胞中的极化运输途径。根据初步研究的结果，提出了一个工作假设。我们的中心假设是，Ral GTPases 在 E-钙粘蛋白介导的细胞粘附启动时被激活，并且它们在特殊膜域（包括顶端连接复合物、桥粒和初级纤毛）形成过程中以时空方式调节胞外囊功能。我们的工作模型是 Ral GTPases 通过与 Sec5 和 Exo84 亚基的顺序相互作用来调节 Exocyst 依赖性运输的不同步骤。这些相互作用反过来又驱动 Exocyst 和“辅助因子”之间的关联/解离循环，“辅助因子”要么将 Exocyst 复合物靶向不同的亚细胞位点，要么为它们在这些位点的特定功能做好准备。最后，我们建议至少两种不同的胞外囊相关复合物被招募到细胞间接触的新生位点，并随后分开以促进不同类型的细胞间连接的发展。本研究的具体目的是：1）研究Ral-Exocyst复合物在调节上皮极化中的功能； 2) 确定 Sec6-Munc18 相互作用如何控制极化胞吐作用； 3) 定义 Sec6 如何靶向 AJC，并确定多个 Exocyst 相关复合物在细胞间连接形成中是否具有不同的功能。总的来说，我们在本申请中提出的研究旨在揭示一种机制的细节，该机制将细胞外事件（即细胞间粘附）与信号通路的激活联系起来，该信号通路在上皮极性建立过程中促进极化膜运输。鉴于我们将重点关注的分子（特别是 Exocyst 和 Ral GTPases）在后生动物中是保守的，我们相信，研究它们如何协作在上皮细胞（例如 AJC 和桥粒）中建立和维持不同的连接复合物将使我们对许多其他细胞类型中调节质膜蛋白复合物组装的机制有重要的了解。因此，这项工作的意义在于，它将指导我们在考虑治疗多种细胞内转运和膜蛋白组装受损的人类疾病时的思考。