Key Points Notch signaling regulates Gcnt1-mediated core-2 O-glycosylation in activated T cells. The core-2 O-glycoform of CD43 reports Notch signals in multiple mouse T cell subsets. Notch signaling is emerging as a critical regulator of T cell activation and function. However, there is no reliable cell surface indicator of Notch signaling across activated T cell subsets. In this study, we show that Notch signals induce upregulated expression of the Gcnt1 glycosyltransferase gene in T cells mediating graft-versus-host disease after allogeneic bone marrow transplantation in mice. To determine if Gcnt1-mediated O-glycosylation could be used as a Notch signaling reporter, we quantified the core-2 O-glycoform of CD43 in multiple T cell subsets during graft-versus-host disease. Pharmacological blockade of Delta-like Notch ligands abrogated core-2 O-glycosylation in a dose-dependent manner after allogeneic bone marrow transplantation, both in donor-derived CD4+ and CD8+ effector T cells and in Foxp3+ regulatory T cells. CD43 core-2 O-glycosylation depended on cell-intrinsic canonical Notch signals and identified CD4+ and CD8+ T cells with high cytokine-producing ability. Gcnt1-deficient T cells still drove lethal alloreactivity, showing that core-2 O-glycosylation predicted, but did not cause, Notch-dependent T cell pathogenicity. Using core-2 O-glycosylation as a marker of Notch signaling, we identified Ccl19-Cre+ fibroblastic stromal cells as critical sources of Delta-like ligands in graft-versus-host responses irrespective of conditioning intensity. Core-2 O-glycosylation also reported Notch signaling in CD8+ T cell responses to dendritic cell immunization, Listeria infection, and viral infection. Thus, we uncovered a role for Notch in controlling core-2 O-glycosylation and identified a cell surface marker to quantify Notch signals in multiple immunological contexts. Our findings will help refine our understanding of the regulation, cellular source, and timing of Notch signals in T cell immunity.

中文翻译：

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GCNT1 介导的唾液酸粘蛋白 CD43 的 O-糖基化是活化 T 细胞中 Notch 信号传导的敏感指标

关键点 Notch 信号在激活的 T 细胞中调节 Gcnt1 介导的 core-2 O-糖基化。CD43 的 core-2 O-糖型报告了多个小鼠 T 细胞亚群中的 Notch 信号。Notch 信号正在成为 T 细胞激活和功能的关键调节器。然而，在激活的 T 细胞亚群中没有可靠的 Notch 信号的细胞表面指标。在这项研究中，我们表明 Notch 信号在小鼠同种异体骨髓移植后，在介导移植物抗宿主病的 T 细胞中诱导 Gcnt1 糖基转移酶基因的表达上调。为了确定 Gcnt1 介导的 O-糖基化是否可以用作 Notch 信号报告基因，我们量化了移植物抗宿主病期间多个 T 细胞亚群中 CD43 的核心 2 O-糖型。在同种异体骨髓移植后，在供体来源的 CD4+ 和 CD8+ 效应 T 细胞以及 Foxp3+ 调节性 T 细胞中，Delta 样 Notch 配体的药理学封锁以剂量依赖性方式消除了核心 2 O-糖基化。CD43 core-2 O-糖基化依赖于细胞内在的经典 Notch 信号，并鉴定出具有高细胞因子产生能力的 CD4+ 和 CD8+ T 细胞。Gcnt1 缺陷的 T 细胞仍然驱动致命的同种异体反应性，表明 core-2 O-糖基化预测但没有引起 Notch 依赖性 T 细胞致病性。使用 core-2 O-糖基化作为 Notch 信号的标志物，我们将 Ccl19-Cre+ 成纤维基质细胞鉴定为移植物抗宿主反应中 Delta 样配体的关键来源，而不管调节强度如何。Core-2 O-糖基化还报告了 CD8+ T 细胞对树突细胞免疫、李斯特菌感染和病毒感染的反应中的 Notch 信号传导。因此，我们发现了 Notch 在控制 core-2 O-糖基化方面的作用，并确定了一种细胞表面标记物，用于量化多种免疫环境中的 Notch 信号。我们的发现将有助于完善我们对 T 细胞免疫中 Notch 信号的调节、细胞来源和时间的理解。