干细胞标志物CD133和E-选凝素相互作用在神经干细胞血管龛中的功能及机制

Stem-cell niche refers to a microenvironment. The stem cell microenvironment includs surrounding blood vessels, immune cells, fibroblasts, bone marrow-derived inflammatory cells and the extracellular matrix (ECM). Exlporing the mechanism regulaing crosstalk between stem cell and surrouding cells, help to developing new theary strategy. Lectins on cell surfaces mediate cell-cell interactions by interacting with glycan. Uncovering the mechanism and function of interaction between lectin and stem cell membrane protein help to eluciding the mechanism regulating crosstalk between stem cell and surrouding cells. CD133/Prominin-1 has received considerable interests due to its widespread use as a marker of various normal and cancer stem cells. Increasing studies indicate that CD133 regulates cell proliferation, differentiation, metabolism and migration. Increasing evidences indicate that the glycosylation status of CD133, rather than the expression of CD133 protein itself, can act as an the marker of stem cells. And, the dynamic glycosylation of CD133 might play a critical role in its biological functions. Our unpublised data showed that CD133 contained sialyl Lewis X in neural stem cell, which was decreased during neural stem cell differentiation. Furthermore, CD133 could interact with E-selectin through sialyl Lewis X. E-selectin promoted the self-renewal of neural stem cell through CD133. In this project, we intend to clarify the structure alteration of sialyl Lewis X structure of CD133 during neural stem cell differentiation, and to investigate the mechanism regulating CD133 Sialyl Lewis X synthesis. Furthermore, we perform to investigate the funcion of the interaction between CD133 and E-selectin. Finally, we use neural stem cell and animal model to explore the funcion and mechanisms of the interaction between CD133 and E-selectin in neural stem cell vascular niche. Through these efforts, we hope to illuminate to explore the fundamental biological aspect of the interaction between CD133 and E-selectin in neural stem cell microenvironment.

阐释干细胞和微环境通讯的机制有助于明晰干细胞命运的调控机制，并为疾病的发病机理、干细胞治疗提供线索。糖链作为生物信息分子，通过和凝集素结合参与细胞通讯。寻找干细胞特征膜蛋白相互作用的凝集素有助于阐释干细胞微环境调控机制。我们前期结果发现：神经干细胞标志物CD133具有唾液酸化路易斯糖X(sialyl Lewis x)结构;分化导致CD133的sialyl Lewis x结构减少；CD133依赖sialyl Lewis x结构与血管内皮细胞E-选凝素相互作用；E-选凝素通过CD133促进神经干细胞自我更新。本项目拟研究神经干细胞中CD133的sialyl Lewis x结构特点、形成关键糖链合成酶，明确CD133与E-选凝素相互作用的机制及其在血管内皮细胞调控神经干细胞特性中的作用与机制。从而揭示出E-选凝素-CD133糖链-胞内信号轴，为阐释微环境调控干细胞特性的机制提供糖生物学思路。

阐释干细胞和微环境通讯的机制有助于明晰干细胞命运的调控机制，并为疾病的发病机理、干细胞治疗提供线索。糖链作为生物信息分子，通过和凝集素结合参与细胞通讯。本项目研究发现了在神经干细胞中CD133具有sialyl Lewis x结构，通过该结构CD133与E-选凝素相互作用，二者的相互作用促进CD133-p85的结合并激活Akt通路从而促进神经干细胞自我更新；分泌的CD133往往具有复合型 N-糖基化，复杂型糖基化通过促进CD133的单泛素化修饰促进CD133分泌；通过高通量的芯片筛选发现LDN193189能结合CD133的C端，并抑制CD133的磷酸化、CD133和p85的结合从而抑制干细胞自我更新。我们的研究重点探明了CD133和E-选凝素结合的糖链结构基础，并阐释二者结合在神经干细胞血管微环境中的生物学意义，从而揭示出E-选凝素-CD133糖链-胞内信号轴，为阐释微环境调控干细胞特性的机制提供糖生物学思路。相关研究发表J Cancer letters1篇、J Cell Mol Med 1篇、FEBS letters 2篇、 J hepatology1篇等5篇论文；申请1项专利。

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