N-Glycosylation and Ocular Surface Homeostasis

项目摘要/摘要 自然界中的所有细胞都被一种不同的葡聚糖混合物所覆盖，这种混合物被称为糖萼，其功能是 与环境的主要接口。糖萼的结构由一系列的 共同组装和加工的糖基转移酶、糖苷酶和糖链修饰酶 单糖部分以组织特有的方式产生细胞表面特征。最新发现 提示细胞表面多聚糖在干细胞中发挥重要作用，并在这两个过程中发挥关键作用 成人的发育过程和动态平衡的维持。 这一提议的中心是我们对细胞表面多聚糖如何促进 维持角膜缘上皮干细胞的动态平衡。干细胞在高分化组织中的增殖能力 必须精确地调节细胞周转，以保持再生能力，同时防止异常 成长。越来越清楚的是，通过核心岩藻糖基化修饰细胞表面受体是 对促进特定的信号转导途径和调节与细胞相关的生物功能至关重要 增殖分化。我们假设缺乏核心岩藻糖基化在 调控角膜缘上皮干细胞的增殖能力及促进其自我更新 属性。 以下具体目标将解决这一目标：(1)识别角膜缘上皮中的多糖特征 干细胞及其在分化过程中的变化，(2)研究FUT8，唯一的 岩藻糖基转移酶，催化核心岩藻糖加成到N-糖链上，调节生长因子受体 在角膜缘上皮细胞中的信号和细胞更新，以及(3)研究核心岩藻糖化是否可以 作为一种分离和移植高度自我更新的角膜缘上皮干细胞的新方法 增殖能力。预计这项研究将具有重大的翻译相关性，因为 角膜缘干细胞缺乏症的细胞替代疗法的新焦点。

Project Summary/Abstract All cells in nature are coated with a diverse mixture of glycans called the glycocalyx that functions as the primary interface with the environment. The structure of the glycocalyx is controlled by a series of glycosyltransferases, glycosidases and glycan-modifying enzymes that collectively assemble and process monosaccharide moieties to generate cell surface signatures in a tissue-specific manner. Recent findings indicate cell surface glycans perform important roles in stem cells and have a critical impact during both developmental processes and maintenance of homeostasis in the adult. This proposal centers on a major gap in our understanding of how cell surface glycans contribute to maintain limbal epithelial stem cell homeostasis. The proliferative capacity of the stem cells in tissues with high cellular turnover has to be precisely regulated to maintain regenerative capacity while preventing abnormal growth. It has become increasingly clear that modification of cell surface receptors by core fucosylation is critical to promote specific signal tranduction pathways and to regulate biological functions relevant to cell proliferation and differentiation. We hypothesize that lack of core fucosylation plays an important role in modulating the proliferative capacity of limbal epithelial stem cells and in promoting their self-renewal properties. The following specific aims will address this objective: (1) to identify glycan signatures in limbal epithelial stem cells and how they change during differentiation, (2) to investigate the contribution of FUT8, the only fucosyltransferase that catalyzes the addition of core fucose to N-glycans, in regulating growth factor receptor signaling and cellular turnover in limbal epithelial cells, and (3) to investigate whether core fucosylation can be used as a novel method to isolate and transplant limbal epithelial stem cells with high self-renewal and proliferative capacities. It is anticipated that this research will have significant translational relevance given the emerging focus on cell replacement therapies for limbal stem cell deficiency.