核心岩藻糖基转移酶调节CD4+ T细胞活化及增殖的作用机理研究

Core fucosyltransferase (Fut8) catalyzes the transfer of a fucose residue from GDP-fucose to the innermost N-acetylglucosamine (GlcNAc) residue of hybrid and complex N-glycans via a1,6-linkage (core fucosylation) in the Golgi apparatus in mammals. The core fucosylation on N-glycans of glycoprotein is only catalyzed by Fut8, which is able to regulate the protein-protein interaction and cell-cell interaction with the change of thier core fucosylation. In germinal center microenvironment, the T cell receptor (TCR) on the CD4+ T cell could recognize the antigen peptide-loaded major histocompatibility class II (MHC-II) on dendritic cells, which is the most important checkpoint during the efficient T cell activation and proliferation. The immune molecules, such as TCR, CD4 and MHC-II, are heavily core fucosylated, suggesting that Fut8 could regulate the process of CD4+ T cell activation and proliferation. To determine the regulation of Fut8 in the process of CD4+ T cell activation and proliferation, we established Fut8+/+OT-II and Fut8-/-OT-II mice using Fut8+/+, Fut8-/- and OT-II mice. In the present program, considerable attention is focused on the research process, such as antigen recognition of CD4+ T cell, CD28/B7 interaction, cytokine secretion, signal transduction, and N-glycan structure analysis, as well as on the mechanism of the regulation of Fut8 in T cell activation and proliferation. These results will lay a foundation for further understanding the process of specific acquired immune response from the new perspective of glycosylations.

T细胞活化及增殖是免疫应答的核心环节。特异性免疫应答过程中，CD4+ T细胞通过T细胞受体(TCR)特异性地识别抗原提呈细胞呈递的抗原肽-MHC-II分子，这是T细胞活化及增殖的关键步骤。参与CD4+ T细胞抗原识别的免疫分子，如TCRab、MHC-II及CD4，均是核心岩藻糖基化糖蛋白。核心岩藻糖基转移酶(Fut8)是通过调节蛋白质的核心岩藻糖基化修饰影响分子间及细胞间相互作用。与Fut8+/+小鼠相比，Fut8-/-小鼠脾脏中CD4+ T细胞数量以及T细胞活化相关基因的表达量明显下降，提示Fut8对CD4+ T细胞活化及增殖具有重要调节作用。本课题拟利用Fut8+/+、Fut8-/-及TCR转基因OT-II小鼠模型，通过开展CD4+ T细胞抗原识别、活化、增殖及糖链结构分析等研究，以阐明Fut8对CD4+ T细胞活化及增殖的调节作用机理，为发现T细胞活化异常相关疾病的诊治提供新的思路。

T细胞活化及增殖是免疫应答的核心环节。特异性免疫应答过程中，CD4+ T细胞通过T细胞受体(TCR)特异性地识别抗原提呈细胞呈递的抗原肽-MHC-II分子，这是T细胞活化及增殖的关键步骤。参与CD4+ T细胞抗原识别的免疫分子，如TCR、MHC-II及CD4，均是核心岩藻糖基化糖蛋白。核心岩藻糖基转移酶(Fut8)是通过调节蛋白质的核心岩藻糖基化修饰影响分子间及细胞间相互作用。我们利用Fut8+/+、Fut8-/-及TCR转基因OT-II小鼠细胞建立CD4+ T细胞—B细胞相互作用模型，进而研究Fut8对CD4+ T细胞活化及增殖的调节作用机理。实验结果表明，与Fut8+/+小鼠相比，Fut8-/-小鼠脾脏中CD4+ T细胞-B细胞相互作用、T细胞活化以及增殖能力明显下降。相关数据在Frontier in Immunology 2018 (IF：5.511)，Molecular Carcinogenesis. 2019(IF：3.851)， mBio, 2019 (IF：6.747)等杂志上发表；并申请2项国内专利（血清IgG核心岩藻糖基水平的检测方法，CN108267578A；一种具有促进双歧杆菌和乳酸杆菌生长的核心岩藻糖基化寡糖及其应用，CN108236115A）；获得2016年大连市科学著作二等奖（2016-11）。本课题主要阐明Fut8对CD4+ T细胞活化及增殖的调节作用机理，为发现T细胞活化异常相关疾病，特别是系统性红斑狼疮（SLE）的诊治提供新的思路。