Molecular and Clinical Glycobiology of the Bone Marrow Environment

血细胞的终身生产需要造血发育计划， 本地信号来传达这些小区的动态需求。这些信号如何在髓内传递 对利基市场仍然知之甚少。本项目的主要研究者已发表和即将发表的大量信息 计划，合作和个人，明确建立了参与聚糖的指导， 造血祖细胞命运、功能，尤其是血小板生成和血小板功能。的 总体假设是“细胞内在和外在聚糖介导的机制调节维持， 造血细胞的分化和功能。”项目1将调查 半乳糖基转移酶β 4GalT 1、β1整联蛋白和糖胺聚糖（GAG）/硫酸乙酰肝素蛋白聚糖 （HSPGs）在稳态和清髓性应激后血小板生成中的作用， “组学”和项目3的标准方法。以前未知的β 4GalT 1调节 还将研究HSPG的巨核细胞（MK）表达。一个函数定义的MK偏置 造血干细胞将与项目2一起研究，特别是关于α 2，6- 唾液酸化的细胞表面，尽管缺乏产生这种结构所必需的St 6 gal 1表达。项目 2将研究细胞外糖基化的作用，特别是由外源性ST 6 GAL 1介导的糖基化， 组合的“组学”方法（项目1），造血小生境中的外源性唾液酸化如何被调节， 确定唾液酸化的细胞表面目标;并与项目3，了解如何新发现的 GAG辅因子调节外源性ST 6 GAL 1活性。临床骨髓增生异常综合征（MDS）和 骨髓增生性肿瘤（MPN）和临床前小鼠模型将用于首次评估， 这些骨髓疾病的糖生物学具有高度异质性，但具有以下共性： 发育不良的MK和改变的血小板数量和功能，并分享这些临床疾病的分析 在这三个项目中。项目3将研究糖胺聚糖与蛋白质的结构-功能关系 在骨髓微环境中，如生长因子及其受体和糖基转移酶。他们的 在促进血小板生成和细胞命运决定中的作用将使用多维度方法进行研究 来鉴定不同的GAG序列项目3将发现合成的GAG模拟物作为 造血/血小板生成用于治疗用途。核心A将监督该计划的管理，核心 B将提供来自批量RNA样品和单细胞的cDNA文库的生成和测序，以及 核心C将进行GAG、蛋白质组学和蛋白质-GAG相互作用的比较结构分析， 蛋白质表达的定量蛋白质组学。这三个项目密切相关，将使用所有核心。 该计划将揭示新的信息，以增加血小板的生产，并帮助了解临床 以MK异常为特征的病症。

The life-long production of blood cells requires hematopoietic developmental programs guided by systemic and local signals to convey the dynamic need for these cells. How these signals are delivered within the intra-medullar niches remain poorly understood. Extensive published and to-be-published information by the PIs of this Program, collaborative and individually, clearly established the involvement of glycans in the guidance of hematopoietic progenitor cell fate, function, and especially in thrombopoiesis and platelet functionality. The overarching hypothesis is “cell-intrinsic and extrinsic glycan-mediated mechanisms regulate maintenance, differentiation, and function of hematopoietic cells.” Project 1 will investigate the roles of the galactosyltransferase β4GalT1, β1 integrin, and glycosaminoglycans (GAGs)/heparan sulfate proteoglycans (HSPGs) in thrombopoiesis at steady-state and following myeloablative stress using novel combined shared “omics” and standard approaches with Project 3. A previously unknown role of β4GalT1 to regulate megakaryocyte (MK) expression of HSPGs will also be investigated. A functionally defined MK-biased hematopoietic stem cell will be investigated together with Project 2, especially with respect to the heavily α2,6- sialylated cell surface despite the absence of St6gal1 expression necessary to generate this structure. Project 2 will investigate the role of extracellular glycosylation, especially that mediated by extrinsic ST6GAL1 using the combined “omics” approach (Project 1), how extrinsic sialylation in the hematopoietic niche is regulated, identifying the cell surface targets of sialylation; and with Project 3, understanding how the newly discovered GAG cofactor modulates extrinsic ST6GAL1 activity. Clinical Myelodysplastic Syndromes (MDS) and Myeloproliferative Neoplasms (MPN) and preclinical mouse models will be used in a first-time assessment into the glycobiology of these marrow diseases of highly heterogenous presentations but with the commonality of dysplastic MKs and altered platelet numbers and function, and analysis of these clinical diseases is shared across all three Projects. Project 3 will investigate the structure–function relationships of GAGs with proteins within the marrow microenvironment, such as growth factors and their receptors, and glycosyltransferases. Their roles in promoting thrombopoiesis and cell fate decisions will be interrogated using a multi-dimensional approach to identifying distinct GAG sequences. Project 3 will discover synthetic GAG mimetics as modulators of hematopoiesis/thrombopoiesis for therapeutic use. Core A will oversee the administration of the program, Core B will provide generation and sequencing of cDNA libraries derived from bulk RNA samples and single cells, and Core C will perform comparative structural analysis of GAGs, proteomics and protein-GAG interactions, and quantitative proteomics of protein expression. The three projects are intimately intertwined and will use all Cores. This program will uncover novel information to increase platelet production and help understand clinical conditions characterized by MK abnormalities.