Studies of O-linked Glycosylation

描述（由申请人提供）：该项目的目标是：(1)开发用于o -链糖基化基础研究的化学工具，(2)鉴定糖蛋白癌症生物标志物。粘蛋白型o -连接糖基化是高等真核生物中膜和分泌蛋白的翻译后修饰。其功能尚不清楚，但黏液型o -连接糖基化的改变与癌症的生长和转移有关。在蛋白质和细胞上干扰和检测o链糖基化都需要化学工具。该更新申请的第一个主要目标是通过靶向o -聚糖生物合成所需的多肽n-乙酰半乳糖氨基转移酶（ppGalNAcTs）和UDP-GlcNAc/GalNAc C4-epimerase (GALE)，开发粘蛋白型o -连接糖基化的小分子抑制剂。这些抑制剂将用于探索o -链聚糖在肿瘤生长和转移中的重要性。第二个目标是开发一种化学方法来快速分析与癌症相关的黏液型o链糖基化的变化。该方法涉及使用n -乙酰半乳糖胺（称为GalNAz）的叠氮类似物对活体动物中的o -连接糖蛋白进行代谢标记。从血清和组织样品中标记的糖蛋白将通过Staudinger连接用磷化氢探针进行化学标记，允许使用蛋白质组学方法进行检测和鉴定。比较正常小鼠和荷瘤小鼠的标记种可能揭示新的疾病血清生物标志物。最终目标是开发一种类似的方法来检测蛋白质O-聚焦化，这是一种最近发现的具有神秘功能的O-连接糖基化形式。已知细胞表面糖参与许多正常和疾病过程，但尚未被用作药物或临床诊断的靶点。这项研究将促进我们对细胞表面糖在肿瘤生长和转移中的作用的理解。在这个项目中开发的化学工具可能会产生新一代抗癌药物和新的早期诊断临床试验。

DESCRIPTION (provided by applicant): The objectives of this project are: (1) the development of chemical tools for fundamental studies of O-linked glycosylation, and (2) the identification of glycoprotein cancer biomarkers. Mucin-type O-linked glycosylation is a posttranslational modification of membrane and secreted proteins in higher eukaryotes. Its functions are poorly understood, but altered mucin-type O-linked glycosylation has been correlated with cancer growth and metastasis. Chemical tools are needed both for perturbing and detecting O-linked glycosylation on proteins and cells. The first major goal of this renewal application is to develop small molecule inhibitors of mucin-type O-linked glycosylation by targeting the polypeptide N-acetylgalactosaminyltransferases (ppGalNAcTs) and UDP-GlcNAc/GalNAc C4-epimerase (GALE), enzymes that are required for O-glycan biosynthesis. The inhibitors will be used to probe the importance of O-linked glycans in tumor growth and metastasis. The second goal is to develop a chemical approach for rapid profiling of changes in mucin-type O-linked glycosylation associated with cancer. The approach involves metabolic labeling of O-linked glycoproteins within living animals using an azido analog of N-acetylgalactosamine (termed GalNAz). The labeled glycoproteins from serum and tissue samples will be chemically tagged with phosphine probes via Staudinger ligation, permitting their detection and identification using proteomic methods. Comparison of labeled species from normal and tumor-bearing mice may reveal new serum biomarkers of disease. The final goal is to develop an analogous method for detection of protein O-fucosylation, a recently discovered form of O-linked glycosylation with mysterious functions. Cell-surface sugars are known to participate in many normal and disease processes, but have not yet been exploited as targets for drugs or clinical diagnostics. This research will advance our understanding of the roles cell-surface sugars play in tumor growth and metastasis. The chemical tools developed in this project may produce a new generation of anti-cancer drugs and new clinical tests for early diagnosis.