Regulation of Granulopoiesis by Fucosylation-Dependent Notch Signaling

描述（由申请人提供）：该资助申请的总体目标是支持K 08职业发展奖，该奖项专注于研究岩藻糖基化依赖性Notch信号通路在髓系命运特化和髓系发育调控中的作用。岩藻糖基化聚糖参与许多生物学过程。岩藻糖基化作为Notch细胞外EGF重复序列上的O-连接岩藻糖部分是各种类型细胞命运特化中Notch信号传导所需的。Lan Zhou是该提案的主要研究者，在她之前与John Lowe博士的工作中，以及她在凯斯西储大学进行的研究中，确定了FX-/-小鼠中的骨髓增殖表型，这些小鼠在细胞岩藻糖基化方面有条件缺陷，这是髓系祖细胞上Notch依赖性信号转导丧失的结果。在这项提案中，周博士将使用转基因Notch报告小鼠来检查骨髓造血干细胞和髓系祖细胞是否由于岩藻糖基化缺陷而抑制了Notch信号转导。然后，她将确定岩藻糖基化缺陷的造血祖细胞是否显示与骨髓基质环境的相互作用改变。她将使用pofut表达缺陷的小鼠进一步研究O-岩藻糖基化在修饰粒细胞生成中Notch信号传导中的作用。介导Notch EGF重复序列的岩藻糖基化，并通过研究pofutl-/- ES细胞体外造血。最后，她将具体检查Notch上的哪种O-岩藻糖残留！EGF重复序列是Notch发挥其调节粒细胞生成作用的重要因素。这将是第一项研究，以确定控制骨髓细胞生成的信号转导途径，激活后的骨髓干细胞和祖细胞的岩藻糖基化糖蛋白，如Notch，与骨髓微环境，并最终有助于调节粒细胞生成的机制。这些研究的结果将提供关于O-岩藻糖基化缺乏引起的Notch信号失调是否在人类慢性骨髓增生性疾病中发挥作用的见解。该提案的结果将为未来的研究提供基础，以探索岩藻糖基化糖蛋白（包括Notch和Notch配体）以及其他分泌或膜相关岩藻糖基化聚糖在造血干细胞自我更新、髓系命运指定和确定以及骨髓生态位能力（支持造血干细胞活性）中的意义。

DESCRIPTION (provided by applicant): The overall goal of this grant application is to support a K08 career development award that focuses on studying the role of the fucosylation-dependent Notch signaling pathway in the regulation of myeloid fate specification and myeloid lineage development. Fucosylated glycans are implicated in many bilogical processes. Fucosylation as O-linked fucose moieties on Notch extracellular EGF repeats is required for Notch signaling in various types of cell fate specification. Lan Zhou, the principle investigator of this proposal, in her previous work with Dr. John Lowe, and in her research conducted at Case Western Reserve University, identified a myeloproliferative phenotype in FX-/- mice, which are conditionally deficient in cellular fucosylation, is consequent to loss of Notch-dependent signal transduction on myeloid progenitor cells. In this proposal, Dr. Zhou will use a transgenic Notch reporter mouse to examine whether the marrrow hematopoietic stem and myeloid progenitor cells have suppressed Notch signal transduction as a consequence of fucosylation deficiency. She will then determine if fucosylation-deficient hematopoietic progenitor cells display altered interactions with the marrow stromal environment. She will further examine the role of O-fucosylation in modifying Notch signaling in granulopoiesis by using mice deficient in the expression of pofut! that mediates the fucosylation of Notch EGF repeats, and by studying the pofutl-/- ES cell in vitro hematopoiesis. Finally, she will examine specifically which O-fucose residue on Notch! EGF repeats is important for Notch to exert its effect in granulopoietic regulation. This will be the first study to define the signaling transduction pathways controlling myelopoiesis that are activated in bone marrow stem and progenitor cells after engagement of fucosylated glycoprotein, such as Notch, with bone marrow microenviroment, and the mechanisms that ultimately contribute to the regulation of granulopoiesis. The outcome of these studies will provide insights as to whether dysregulated Notch signaling consequent to deficiency of O-fucosylation could play a role in human chronic myeloproliferative diseases. Resutls from the proposal will provide the basis for future studies to explore the significance of fucosylated glycoproteins including Notch and Notch ligands, and, perhaps other secreted or membrane associated fucosylated glycans, in hematopoietic stem cell self-renewal, myeloid fate specification and determination, and bone marrow niche competency in supproting hematopoietic stem cell activity.