Investigating the molecular mechanisms of glycosaminoglycan assembly

标题：研究糖胺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聚糖（GAG）的生物合成中。糖胺聚糖是一种长的线性多糖 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，包括细胞信号传导和 发展这些复杂的碳水化合物通常附着在核心蛋白上，称为蛋白聚糖， 位于细胞表面和细胞外基质中，并且链由交替的 葡糖胺和糖醛酸糖残基的非均相N-和O-硫酸化。的生物合成 糖胺聚糖是一种非模板化过程，由定位于蛋白质的一大家族酶的协同活动驱动。 高尔基体和内质网。硫酸化糖残基的排列和方向指定了 细胞表面上不同配体结合位点的位置，并且这些修饰可以在时间上变化， 发育和空间上跨越组织。糖胺聚糖结合配体的能力影响了糖胺聚糖的基本功能。 细胞的性质、形成组织和器官的能力以及正常生理学。尽管关键功能 这些分子，有一个显着的知识差距有关的监管机制，引起 它们的可变组成和粘合性能。通过多学科研究计划， 在功能基因组学，细胞生物学和糖生物学的优势，我们的目标是确定和表征 涉及控制细胞中GAG结构和功能的固有多样性的机制。特别 感兴趣的是，染色质重塑复合物在发育过程中调节GAG组装以及在 疾病状态，因为我们最近确定的成员polycomb抑制复合物（PRC）作为新的 GAG酶表达和组装的表观遗传修饰剂。我们假设定义的表观遗传和 转录程序在不同的细胞类型中调节生物合成酶的表达，从而调节它们的功能。 与细胞外基质中过多的生长因子和其他结合配偶体相互作用。我们还旨在 研究核心生物合成机制如何在内质网和高尔基体中原位调节。 我们计划探索ER中生物合成酶和核心蛋白聚糖的物理联系， 高尔基体，并确定未知的伴侣和/或支架蛋白，可能会调整糖基化的分泌 通路为了开展这项工作，我们将利用我们在分析GAG结构，功能， 和调控，以了解：（1）转录因子和染色质重塑复合物如何控制 GAG生物合成酶的表达，影响GAG结构和功能，（2）蛋白质-蛋白质如何 ER和高尔基体的相互作用协调了不同细胞类型中的蛋白聚糖组装，以及（3）如何 蛋白聚糖核心蛋白充当GAG组装的支架。总的来说，我们预计这一奋进将大大 推进我们对糖基化调控机制的认识，并提供新的策略 并靶向操纵人类疾病中的GAG生物合成。

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.