Development of Biochemical Tools and Approaches for Studying Siglecs

四种主要类型的生物分子组成活细胞：蛋白质，核酸，脂质和寡糖。其中，寡糖也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，聚糖的组装是通过酶的连续作用以空间和时间控制的方式控制的。由于这个原因和其他原因，聚糖在化学和生物化学上是复杂的，使其研究具有内在的挑战性。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，有相当大的机会开发创新的策略来分析和操纵细胞聚糖;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内，因为它们被白色血细胞上表达的大量聚糖结合蛋白（GBP）识别为配体。虽然已经在免疫细胞上描述了许多关于GBP-聚糖相互作用的功能，但是关于这些相互作用控制免疫细胞功能的潜在机制仍然有很多需要了解。我的实验室研究了GBP的Siglec（唾液酸结合免疫球蛋白型凝集素）家族，该家族含有高度复杂的聚糖配体。Siglecs具有免疫调节特性，其通过与其聚糖配体的相互作用来调节。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聚糖配体的新方法来充分实现。在这项研究计划中，我们将推进各种互补方法，用于解剖Siglec的聚糖配体（例如质谱法，流式细胞术和脂质体纳米颗粒），并反过来开发化学工具来操纵这些聚糖。使用化学生物学方法和尖端基因组编辑的协同组合，总体目标是开发可用于询问Siglecs调节免疫细胞功能的功能的策略，该策略可应用于研究GBP作用的更广泛的研究科学家社区。

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.