Development of Biochemical Tools and Approaches for Studying Siglecs

四种主要的生物分子构成了活细胞：蛋白质、核酸、脂质和低聚糖。其中，寡糖也被称为聚糖，是唯一一种没有自组装（脂质）或模板驱动的生物合成（蛋白质和DNA/RNA）的类型。相反，聚糖的组装是由酶在空间和时间上控制的连续作用控制的。由于这个原因和其他原因，聚糖在化学上和生物化学上都很复杂，这使得它们的研究具有固有的挑战性。因此，操纵聚糖的工具落后于相对完善的操纵遗传密码的方法。因此，有相当大的机会发展创新的策略来分析和操作细胞聚糖；事实上，新的工具将有利于广泛的科学家研究聚糖的生物学作用。聚糖的一个关键作用是在免疫系统中，因为它们被白细胞上表达的大量聚糖结合蛋白（GBPs）识别为配体。虽然gbp -聚糖相互作用在免疫细胞上的许多功能已经被描述，但这些相互作用控制免疫细胞功能的潜在机制仍有待了解。我的实验室研究Siglec（唾液酸结合免疫球蛋白型凝集素）GBPs家族，它含有高度复杂的聚糖配体。Siglecs具有免疫调节特性，这是通过与它们的聚糖配体相互作用来调节的。了解Siglecs控制免疫细胞功能的机制只能通过开发分析和调节其糖聚糖配体的新方法来充分实现。在这个研究项目中，我们将推进各种互补的方法来解剖Siglec的聚糖配体（如质谱，流式细胞术和脂质体纳米颗粒），反过来，开发化学工具来操纵这些聚糖。通过化学生物学方法和尖端基因组编辑的协同结合，总体目标是制定可用于询问Siglecs调节免疫细胞功能的策略，这可以应用于研究GBPs作用的更广泛的研究科学家群体。

Four major types of biomolecules make up living cells: proteins, nucleic acids, lipids, and oligosaccharides. Of these, oligosaccharides also known as glycans are the only type in which there is no self-assembly (lipids) or template-driven biosynthesis (protein and DNA/RNA). Instead, the assembly of glycans is controlled by the successive actions of enzymes in a spatially- and temporally-controlled manner. For this reason, and others, glycans are chemically and biochemically complex, making their study inherently challenging. Consequently, tools that manipulate glycans lag behind the comparatively well-establish methodologies of manipulating the genetic code. Accordingly, there is considerable opportunity for developing innovative strategies to analyze and manipulate cellular glycans; indeed, new tools would benefit a broad range of scientists studying the biological roles for glycans. One key role of glycans is within the immune system as they are recognized as ligands by a plethora of glycan-binding proteins (GBPs) expressed on white blood cells. While many functions for GBP-glycan interactions have been described on immune cells, there is still much to be learned about the underlying mechanisms through which these interactions control immune cell function. My lab studies the Siglec (sialic acid-binding immunoglobulin-type lectin) family of GBPs which contains glycan ligands that are highly complex. Siglecs have immunomodulatory properties, which are regulated by interactions with their glycan ligands. Understanding the mechanisms by which Siglecs control immune cell function can only be fully realized by developing new approaches to analyze and modulate their glycan ligands. In this program of research, we will advance a variety of complementary approaches for dissecting glycan ligands for Siglec (e.g. mass spectrometry, flow cytometry, and liposomal nanoparticles) and, in turn, develop chemical tools to manipulate these glycans. Using a synergistic combination of chemical biology approaches and cutting-edge genome editing, the overall objective is to develop strategies that can be used for interrogating the function of Siglecs regulating immune cell function, which can be applied to the wider community of research scientists studying the roles of GBPs.