Regulation of Granulopoiesis by Fucosylation-Dependent Notch Signaling

描述（由申请人提供）：本拨款申请的总体目标是支持K08职业发展奖，该奖项侧重于研究聚焦依赖性Notch信号通路在髓细胞命运规范和髓细胞谱系发育的调节中的作用。浓缩聚糖参与许多生物过程。在各种类型的细胞命运规范中，Notch信号需要将o -连锁聚焦片段集中在Notch细胞外EGF重复序列上。该提案的主要研究者Lan Zhou，在她之前与John Lowe博士的工作中，以及在凯斯西储大学进行的研究中，在FX-/-小鼠中发现了一种骨髓增生性表型，这种表型是细胞聚焦有条件缺陷的，这是由于骨髓祖细胞上notch依赖性信号转导的缺失造成的。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骨髓祖细胞是否由于聚焦化缺陷而抑制了Notch信号转导。然后，她将确定聚焦缺陷造血祖细胞是否显示与骨髓基质环境相互作用的改变。她将通过使用pofut表达不足的小鼠，进一步研究O-聚焦在改变Notch信号在颗粒形成中的作用！介导Notch EGF重复序列的聚焦，并通过研究胚胎干细胞在体外造血中的作用。最后，她将具体检查Notch上的O聚焦残留物。EGF重复序列对于Notch发挥其在粒细胞生成调控中的作用至关重要。这将是首次研究确定骨髓干细胞和祖细胞中，当集中的糖蛋白（如Notch）与骨髓微环境接触后，控制骨髓生成的信号转导通路，以及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-聚焦缺失导致的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。这项研究的结果将为未来的研究提供基础，以探索包括Notch和Notch配体在内的聚焦糖蛋白，以及其他分泌的或膜相关的聚焦糖蛋白，在造血干细胞自我更新、骨髓命运规范和决定以及骨髓生态位能力支持造血干细胞活性方面的意义。

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.