Chitinase 3–like-1 (Chi3l1) and IL-13 are both ligands of IL-13 receptor α2 (IL-13Rα2). The binding of the former activates mitogen-activated protein kinase, AKT, and Wnt/β-catenin signaling, and plays important roles in innate and adaptive immunity, cellular apoptosis, oxidative injury, allergic inflammation, tumor metastasis and wound healing, fibrosis, and repair in the lung. In contrast, the latter binding is largely a decoy event that diminishes the effects of IL-13. Here, we demonstrate that IL-13Rα2 N-glycosylation is a critical determinant of which ligand binds. Structure–function evaluations demonstrated that Chi3l1–IL-13Rα2 binding was increased when sites of N-glycosylation are mutated, and studies with tunicamycin and Peptide:N-glycosidase F (PNGase F) demonstrated that Chi3l1–IL-13Rα2 binding and signaling were increased when N-glycosylation was diminished. In contrast, structure–function experiments demonstrated that IL-13 binding to IL-13Rα2 was dependent on each of the four sites of N-glycosylation in IL-13Rα2, and experiments with tunicamycin and PNGase F demonstrated that IL-13–IL-13Rα2 binding was decreased when IL-13Rα2 N-glycosylation was diminished. Studies with primary lung epithelial cells also demonstrated that Chi3l1 inhibited, whereas IL-13 stimulated, N-glycosylation as evidenced by the ability of Chi3l1 to inhibit and IL-13 to stimulate the subunits of the oligosaccharide complex A and B (STT3A and STT3B). These studies demonstrate that N-glycosylation is a critical determinant of Chi3l1 and IL-13 binding to IL-13Rα2, and highlight the ability of Chi3l1 and IL-13 to alter key elements of the N-glycosylation apparatus in a manner that would augment their respective binding.

几丁质酶 3-like-1 (Chi3l1) 和 IL-13 都是 IL-13 受体 α2 (IL-13Rα2) 的配体。前者的结合激活丝裂原活化蛋白激酶、AKT 和 Wnt/β-catenin 信号，并在先天性和适应性免疫、细胞凋亡、氧化损伤、过敏性炎症、肿瘤转移和伤口愈合、纤维化和修复肺部。相比之下，后者的结合在很大程度上是一种诱饵事件，可以减弱 IL-13 的作用。在这里，我们证明 IL-13Rα2 N-糖基化是哪个配体结合的关键决定因素。结构 - 功能评估表明，当N位点时 Chi3l1-IL-13Rα2 结合增加-糖基化发生突变，并且对衣霉素和肽：N-糖苷酶 F（PNGase F）的研究表明，当N-糖基化减少时，Chi3l1–IL-13Rα2 的结合和信号传导会增加。相比之下，结构-功能实验表明 IL-13 与 IL-13Rα2 的结合依赖于 IL-13Rα2 中四个N-糖基化位点中的每一个，并且衣霉素和 PNGase F 的实验表明 IL-13-IL-13Rα2当 IL-13Rα2 N-糖基化减少时，结合减少。对原代肺上皮细胞的研究还表明 Chi3l1 抑制，而 IL-13 刺激，N- 糖基化由 Chi3l1 抑制和 IL-13 刺激寡糖复合物 A 和 B（STT3A 和 STT3B）亚基的能力所证明。这些研究表明，N-糖基化是 Chi3l1 和 IL-13 与 IL-13Rα2 结合的关键决定因素，并强调了 Chi3l1 和 IL-13 以某种方式改变N-糖基化装置关键元素的能力各自绑定。