Biosynthesis and Function of Lactosaminyl Glycans in Hematopoiesis

描述（由申请人提供）：中性粒细胞减少症和血小板减少症继发的感染和出血分别是放化疗近期发病率和死亡率的主要原因。造血干细胞/祖细胞（HSPCs）在被称为“壁龛”的特殊骨髓微结构域中增殖和分化，这是由关键的细胞-细胞和细胞-基质粘附相互作用决定的。众所周知，末端乳胺基聚糖（即附着在细胞膜蛋白质或脂质上的碳水化合物链的远端）的唾液基和/或聚焦基修饰的表达介导和/或调节多种粘附相互作用。该建议的中心假设是，这些细胞表面聚糖对维持HSPCs和决定谱系命运的骨髓壁龛的形成具有关键的影响。具体来说，我们希望阐明末端乳胺基聚糖在调节骨髓生成和血栓形成过程中的作用。我们试图获得有关末梢乳糖胺基聚糖在相关祖细胞相关支架上的分期和谱系特异性分布的基本信息，以及指导其表达的生物合成途径，其结构生物学（连接和分支/多样性），其对骨髓粘附相互作用的影响，以及它们对克隆原性的影响。该计划提案采用多学科方法来解决这些核心问题，提供整合到三个相互交织的项目中的协同结构-功能研究：项目1 （Sackstein）将使用来自临床相关来源的原代人HSPCs来阐明晚期乳胺基聚糖在早期造血细胞和骨髓细胞中的时空表达和功能，并将制定重塑表面乳胺基聚糖的策略；项目2 （Lau）将研究人类和小鼠HSPCs，以确定直接晚期乳胺基聚糖特异性表达的生物合成途径；项目3 （Hoffmeister）将研究小鼠和人类巨核细胞祖细胞和巨核细胞，以确定血栓形成过程中末端乳胺基聚糖的时间变化和功能，并分析血小板在介导外源性糖基化途径中的作用。此外，该计划将建立新的技术资源来询问聚糖的结构和功能，并将建立一个糖科学技能发展核心，为创造具有必要知识和技能的新研究人员提供必要的背景，工具和技术培训，以推动翻译糖生物学领域的发展。因此，预计本项目提出的实验和方法将解决糖生物学和造血中的关键问题，从而实现变革性的治疗策略，以定制修饰表面聚糖来优化骨髓和血小板生成，将扩大聚糖分析资源，并将从根本上指导/培养下一代科学家，他们需要在糖科学和医疗需求的界面进行研究。相关性：白细胞和血小板缺乏与癌症治疗有关，也发生在骨髓疾病中。这项研究应该会产生新的治疗方法来改善这种情况下的骨髓功能。（摘要结束）

DESCRIPTION (provided by applicant): Infection and bleeding secondary to neutropenia and thrombocytopenia, respectively, are the major causes of near-term morbidity and mortality from chemoradiotherapy. Hematopoietic stem/progenitor cells (HSPCs) proliferate and differentiate in specialized bone marrow microarchitectural domains known as "niches" dictated by critical cell-cell and cell-matrix adhesive interactions. It is well-recognized that expression of sialyl and/or fucosyl modifications of terminal lactosaminyl glycans (i.e., at distal end of carbohydrate chains attached to protein or lipid of the cell membrane) mediate and/or modulate multiple adhesive interactions. The central hypothesis of this proposal is that these cell surface glycans critically shape formation of marrow niches that sustain HSPCs and dictate lineage fate decisions. Specifically, we wish to elucidate the role(s) of terminal lactosaminyl glycans in regulating myelopoietic and thrombopoletic processes. We seek to obtain fundamental information regarding the stage- and lineage-specific distribution of terminal lactosaminyl glycans on pertinent scaffolds of relevant progenitor cells and the biosynthetic pathway(s) that direct their expression, their structural biology (linkages and branching/multiplicity), their influence(s) on marrow adhesive interactions, and, altogether, their effect(s) on clonogenicity. This program proposal employs a multidisciplinary approach to address these central issues, offering synergistic structure-function studies integrated into three interwoven projects: Project 1 (Sackstein) will use primary human HSPCs derived from clinically-relevant sources to elucidate the temporospatial expression and function of terminal lactosaminyl glycans in early hematopoietic and myelopoietic cells, and will develop strategies to remodel surface lactosaminyl glycans; Project 2 (Lau) will investigate human and mouse HSPCs to identify the biosynthetic pathways that direct stage-specific expression of terminal lactosaminyl glycans; Project 3 (Hoffmeister) will study mouse and human megakaryocyte progenitors and megakaryocytes to define the temporal changes and function(s) of terminal lactosaminyl glycans during thrombopoiesis, and will analyze the role(s) of platelets in mediating extrinsic glycosylation pathways. Moreover, this program will establish new technical resources to interrogate glycan structure and function, and will establish a glycosciences skills development core that will provide training in the background, tools and techniques necessary for the creation of new investigators possessing the requisite knowledge and skills to drive forward the field of translational glycobiology. Thus, it is anticipated that the experiments and approaches proposed in this program will address key questions in glycobiology and in hematopoiesis enabling transformative therapeutic strategies to custom-modify surface glycans to optimize myelopoiesis and thrombopoiesis, will expand glycan analytical resources, and will also fundamentally serve to mentor/nurture the future generation(s) of scientists required to undertake investigations at the interface of glycoscience and medical necessity. RELEVANCE: Deficiency in white cells and platelets is associated with cancer treatment, and also occurs in bone marrow diseases. This research effort should yield new treatments to improve marrow function in such conditions. (End of Abstract)