Investigating the molecular mechanisms of glycosaminoglycan assembly

研究糖胺多聚糖组装的分子机制 项目摘要 这项研究计划的长期目标是阐明和理解所涉及的调控机制。 在哺乳动物细胞中糖胺多聚糖(GAG)的生物合成。GAG是一种长而线形的多糖 它们在所有动物细胞上表达，并在许多细胞过程中发挥关键作用，包括细胞信号和 发展。这些复杂的碳水化合物通常附着在被称为蛋白多糖的核心蛋白质上， 位于细胞表面和细胞外基质中，链由交替的 氨基葡萄糖和糖醛酸糖残基是N-和O-硫酸盐的异质性。……的生物合成 GAGS是一个非模板化的过程，由定位于 高尔基体和内质网。硫酸盐化糖渣的排列和取向规定了 在细胞表面上不同的配体结合部位的位置，这些修饰可以在时间上变化 发育和跨组织的空间分布。GAG结合配体的能力影响基本的 细胞的特性，形成组织和器官的能力，以及正常的生理学。尽管具有以下关键功能 在这些分子中，关于引起 它们的可变组成和结合特性。通过一个多学科的研究计划，利用 在功能基因组学、细胞生物学和糖生物学方面的优势，我们的目标是识别和表征 参与控制细胞内GAG结构和功能的固有多样性的机制。特别的 有趣的是，染色质重塑复合体在调节发育过程中和 疾病状态，因为我们最近发现多梳抑制复合体(PRC)的成员是新的 Gag酶表达和组装的表观遗传修饰物。我们假设定义了表观遗传学和 转录程序调节不同细胞类型中生物合成酶的表达，这调节了它们的 与细胞外基质中过多的生长因子和其他结合伙伴相互作用。我们还瞄准了 研究核心生物合成机制在内质网和高尔基体中的原位调节。 我们计划探索内质网和内质网中生物合成酶和核心蛋白多糖的物理联系。 高尔基体，并鉴定未知的伴侣和/或支架蛋白，这些蛋白可能调节分泌中的糖基化 路径。为了开展这项工作，我们将利用我们的历史优势，分析GAG的结构、功能 和调控：(1)转录因子和染色质重塑复合体如何控制 GAG生物合成酶的表达，对GAG结构和功能的影响，(2)蛋白质-蛋白质 内质网和高尔基体中的相互作用如何协调不同细胞类型中的蛋白多糖组装，以及(3)如何 蛋白多糖核心蛋白作为GAG组装的支架。总体而言，我们预计这一努力将显著 增进我们对糖基化调控机制的认识，并提供新的策略 目标是操纵人类疾病中的GAG生物发生。

Title: Investigating the molecular mechanisms of glycosaminoglycan assembly Project Summary The long-term goal of this research program is to elucidate and understand the regulatory mechanisms involved in the biosynthesis of glycosaminoglycans (GAGs) in mammalian cells. GAGs are long, linear polysaccharides that are expressed on all animal cells and play a key role in many cellular processes, including cell signaling and development. These complex carbohydrates are typically attached to core proteins, known as proteoglycans, located on the cell surface and in the extracellular matrix, and the chains are composed of alternating glucosamine and uronic acid sugar residues that are heterogeneously N- and O-sulfated. The biosynthesis of GAGs is a non-templated process, driven by the concerted activity of a large family of enzymes localized to the Golgi and endoplasmic reticulum. The arrangement and orientation of the sulfated sugar residues specify the location of distinct ligand binding sites on the cell surface, and these modifications can vary temporally during development and spatially across tissues. The capacity of GAGs to bind ligands impacts the fundamental properties of cells, the ability to form tissues and organs, and normal physiology. Despite the key functions of these molecules, there is a significant gap in knowledge regarding the regulatory mechanisms that give rise to their variable composition and binding properties. Through a multidisciplinary research program that leverages strengths in functional genomics, cell biology, and glycobiology, we aim to identify and characterize the mechanisms involved in controlling the inherent diversity of GAG structure and function in cells. Of particular interest, is the role of chromatin remodeling complexes in regulating GAG assembly during development and in disease states, as we recently identified members of the polycomb repressive complex (PRC) as novel epigenetic modifiers of GAG enzyme expression and assembly. We hypothesize that defined epigenetic and transcriptional programs tune the expression of biosynthetic enzymes in distinct cell types, which modulates their interaction with a plethora of growth factors and other binding partners in the extracellular matrix. We also aim to investigate how the core biosynthetic machinery is regulated in situ in the endoplasmic reticulum and Golgi. We plan to explore the physical association of the biosynthetic enzymes and core proteoglycans in the ER and Golgi and identify unknown chaperone and/or scaffolding proteins that may tune glycosylation in the secretory pathway. To carry out this work, we will leverage our historic strengths in the analysis of GAG structure, function, and regulation to understand: (1) how transcription factors and chromatin remodeling complexes control the expression of GAG biosynthetic enzymes, which impacts GAG structure and function, (2) how protein-protein interactions in the ER and Golgi orchestrate proteoglycan assembly in distinct cell types, and (3) how proteoglycan core proteins act as scaffolds for GAG assembly. Overall, we expect this endeavor to significantly advance our knowledge regarding the regulatory mechanisms controlling glycosylation and offer new strategies and targets to manipulate GAG biogenesis in human disease.