Protein-Specific Polysialylation

蛋白质特异性多唾液酸化

• 批准号: 6365409
• 负责人: KAREN J. COLLEY
• 金额: $ 25.83万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6365409
• 关键词: N acylation; carcinogenesis; cell adhesion; cell growth regulation; cell line; cell membrane; cell migration; chimeric proteins; developmental neurobiology; enzyme substrate; gene expression; glycoproteins; glycosylation; high performance liquid chromatography; immunoprecipitation; molecular site; neural cell adhesion molecules; neurogenesis; posttranslational modifications; protein sequence; protein structure function; radiotracer; sialyltransferases; site directed mutagenesis; surface property; transfection

DESCRIPTION (provided by applicant): The presence of long chains of alpha2, 8-polysialic acid (PSA) on cell surface glycoproteins negatively modulates cell adhesion by preventing cells from closely apposing one another. During development, PSA functions in axon guidance, axon pathfinding and cell migration. In the adult animal, its expression persists in areas of the brain requiring morphofunctional plasticity, and it is re-expressed in various cancer cells where it is thought to contribute to their highly metastatic behavior. PSA is a protein-specific modification that is found on a small group of proteins that includes the neural cell adhesion molecule (NCAM), the a subunit of the voltage-dependent sodium channel, and the polysialyltransferases PST and STX. What directs the polysialyltransferases to recognize specific glycoproteins is not known. We hypothesize that the polysialyltransferases recognize some amino acid sequence or structural feature of the glycoprotein substrate, and that this initial protein-protein interaction allows the specific polysialylation of oligosaccharides. In the first aim of this proposal we will elucidate the protein signals mediating NCAM polysialylation. We have established that the two polysialyltransferases, PST and STX, are autopolysialylated in cells. In the second aim of this proposal we will investigate the process of enzyme autopolysialylation and how the autopolysialylation of PST impacts NCAM polysialylation. We demonstrated that the MCF7 human breast carcinoma line and the RBL rat basophilic leukemia line express high levels of PSA and PST, but not NCAM or the sodium channel. We hypothesize that the PSA detected in these cells is modifying endogenous PST. In the third specific aim, we will determine what polysialylated proteins are present in these cells to test the hypothesis that autopolysialylated PST is expressed at appropriate levels and locations to impact the interactions of these cells. The overall goal of these and future studies is to understand the mechanism of protein-specific polysialylation and the role that PSA plays in the function of the proteins it modifies.

描述（由申请人提供）：存在 alpha2 长链， 细胞表面糖蛋白上的 8-聚唾液酸 (PSA) 对细胞产生负调节 通过防止细胞彼此紧密贴合来实现粘附。期间 发育、PSA 在轴突引导、轴突寻路和细胞中发挥作用 迁移。在成年动物中，其表达持续存在于大脑区域 需要形态功能可塑性，并且在各种癌症中重新表达 人们认为它有助于细胞的高度转移行为。 PSA 是一种蛋白质特异性修饰，存在于一小群 包括神经细胞粘附分子 (NCAM)（a 亚基）的蛋白质 电压依赖性钠通道以及聚唾液酸转移酶 PST 和 STX。是什么引导聚唾液酸转移酶识别特定的 糖蛋白尚不清楚。我们假设聚唾液酸转移酶 识别糖蛋白的某些氨基酸序列或结构特征 底物，并且这种最初的蛋白质-蛋白质相互作用允许 寡糖的特异性多唾液酸化。在本提案的第一个目标中 我们将阐明介导 NCAM 多唾液酸化的蛋白质信号。我们有 确定两种聚唾液酸转移酶 PST 和 STX 在细胞中自多唾液酸化。在本提案的第二个目标中，我们将 研究酶自聚唾液酸化的过程以及如何 PST 的自多唾液酸化影响 NCAM 多唾液酸化。我们证明了 MCF7人乳腺癌系和RBL大鼠嗜碱性白血病系 表达高水平的 PSA 和 PST，但不表达 NCAM 或钠通道。我们 假设在这些细胞中检测到的 PSA 正在改变内源性 PST。 在第三个具体目标中，我们将确定什么是多唾液酸化蛋白质 存在于这些细胞中以检验自多唾液酸化 PST 的假设 在适当的水平和位置表达以影响相互作用 这些细胞。这些和未来研究的总体目标是了解 蛋白质特异性多唾液酸化的机制以及PSA在其中的作用 它所修饰的蛋白质的功能。