Mechanism and Regulation of Protein-Specific Polysialylation

蛋白质特异性多唾液酸化的机制和调控

• 批准号: 8666557
• 负责人: KAREN J. COLLEY
• 金额: $ 29.79万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-20 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8666557
• 关键词: Abbreviations; Adhesives; Alternative Splicing; Amino Acids; Binding; Biochemistry; Cell Adhesion Molecules; Cell-Cell Adhesion; Cells; Cleaved cell; Coupled; Defect; Development; Disease; Employee Strikes; Exhibits; Fibronectins; Growth; Human; Immunoglobulin Domain; Immunoglobulin Variable Region; Immunoglobulins; Length; Malignant Neoplasms; Mediating; Membrane; Modification; Natural regeneration; Nerve Regeneration; Neural Cell Adhesion Molecules; Neurons; Neuropilin-2; Peripheral; Physiological; Play; Polymers; Polysaccharides; Polysialic Acid; Positioning Attribute; Process; Protein Isoforms; Proteins; RNA Splicing; Regulation; Role; ST8Sia II; Semaphorins; Sialyltransferases; Signal Transduction; Signaling Protein; Specificity; Substrate Interaction; Surface; Synapses; Synaptic plasticity; Testing; Therapeutic; Time; Tissues; Vascular Endothelial Growth Factors; Work; axon guidance; cancer type; cell motility; endo-alpha-sialidase; experience; flexibility; glycosylation; mutant; nervous system development; polymerization; protein function; receptor; repaired; research study; sugar

DESCRIPTION (provided by applicant): More than half of all human proteins are glycosylated, and the physiological significance of glycosylation is exemplified by the numerous instances in which variable glycosylation compromises protein function and causes developmental defects and disease. Despite this, the factors that control which glycans are assembled on proteins are not well understood. Polysialylation is a striking example of a protein specific modification that can dramatically change protein function. Polysialic acid (polySia) is best known for its ability to block neural cell adhesion molecule (NCAM)-dependent cell adhesion and signaling, and for its roles in cell migration, axon guidance, synaptic plasticity, an nervous system development. PolySia is also upregulated on damaged peripheral neurons and facilitates their regeneration, and on the surface of several different types of cancers where it promotes their growth and invasiveness. Remarkably, polySia is found on only five proteins in addition to the polysialyltransferases (polySTs) that modify their own N-glycans. The recent identification of two of these polyST substrates, SynCAM 1, a synaptic adhesion molecule, and neuropilin-2 (NRP-2), a semaphorin and VEGF co-receptor, suggests that the roles of polySia may be more extensive than previously thought, and raises the question of how the polySTs recognize and modify these distinct substrates. Our long-term objectives are to determine the mechanism of protein specific polysialylation, what factors regulate the polymerization of polySia chains on specific substrates, and how polySia modulates the functions of the proteins it modifies. In this proposal we will test the hypothesis that the polySTs recognize common amino acid and structural features of their substrates and that this interaction allows an initial polymerization of the polySia chain on a substrate's glycans, and that this is followed by a polyST-polySia chain interaction that promotes further chain elongation. To do this we will evaluate the domain and sequence requirements for polyST recognition and polysialylation of NCAM, SynCAM 1 and NRP-2, and determine whether residues in a conserved polyST polybasic region mediate substrate protein and/or polySia chain interaction to promote protein specific polySia chain polymerization. We will also test the hypothesis that changes in the length of the stalk regions of SynCAM 1 and NRP-2, generated by alternative splicing, alter their alignment with membrane- associated polySTs and control the polysialylation of these proteins in a cell- and tissue-specific manner. We anticipate that these studies will allow us to identify points in the polysialylation process that are subject to physiological regulation, and that will b amenable to experimental and therapeutic manipulations to control substrate polysialylation and function during development, repair, and disease.

描述（由申请人提供）：超过一半的人类蛋白质被糖基化，并且糖基化的生理意义通过许多实例得到例证，其中可变的糖基化损害蛋白质功能并导致发育缺陷和疾病。尽管如此，控制哪些聚糖在蛋白质上组装的因素尚不清楚。多唾液酸化是蛋白质特异性修饰的一个引人注目的例子，它可以显着改变蛋白质功能。聚唾液酸 (polySia) 因其阻断神经细胞粘附分子 (NCAM) 依赖性细胞粘附和信号传导的能力，以及其在细胞迁移、轴突引导、突触可塑性和神经系统发育中的作用而闻名。 PolySia 还在受损的周围神经元上表达上调，促进其再生，并在几种不同类型的癌症表面上表达，促进其生长和侵袭。值得注意的是，除了修饰自身 N-聚糖的聚唾液酸转移酶 (polyST) 之外，仅在五种蛋白质上发现了 polySia。最近对其中两种 PolyST 底物 SynCAM 1（一种突触粘附分子）和 Neuropilin-2 (NRP-2)（一种信号蛋白和 VEGF 共受体）的鉴定表明，polySia 的作用可能比以前想象的更广泛。并提出了 PolyST 如何识别和修饰这些不同底物的问题。我们的长期目标是确定蛋白质特异性聚唾液酸化的机制，哪些因素调节特定底物上polySia链的聚合，以及polySia如何调节其修饰的蛋白质的功能。在本提案中，我们将测试以下假设：polyST 识别其底物的常见氨基酸和结构特征，并且这种相互作用允许 PolySia 链在底物聚糖上进行初始聚合，随后进行 PolyST-polySia 链相互作用促进链进一步伸长。为此，我们将评估 NCAM、SynCAM 1 和 NRP-2 的 PolyST 识别和聚唾液酸化的结构域和序列要求，并确定保守的 PolyST 多碱基区域中的残基是否介导底物蛋白和/或 PolySia 链相互作用以促进蛋白质特异性 PolySia链聚合。我们还将测试以下假设：通过选择性剪接产生的 SynCAM 1 和 NRP-2 茎区长度的变化，改变它们与膜相关的 PolyST 的排列，并控制这些蛋白质在细胞和组织中的聚唾液酸化。具体方式。我们预计这些研究将使我们能够确定聚唾液酸化过程中受生理调节的点，并且这些点将适合实验和治疗操作以控制发育、修复和疾病期间的底物聚唾液酸化和功能。