A Novel N-Tetrasaccharide in Patients with Congenital Disorders of Glycosylation, Including Asparagine-Linked Glycosylation Protein 1, Phosphomannomutase 2, and Mannose Phosphate Isomerase Deficiencies.
A Novel N-Tetrasaccharide in Patients with Congenital Disorders of Glycosylation, Including Asparagine-Linked Glycosylation Protein 1, Phosphomannomutase 2, and Mannose Phosphate Isomerase Deficiencies.
复制标题
一种新型的N-四糖，用于先天性糖基化的患者，包括天冬酰胺连接的糖基化蛋白1，磷酸磷酸酶2和磷酸甘露糖异构酶缺乏症。
DOI：
10.1373/clinchem.2015.243279
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发表时间：
2016-01
影响因子：
9.3
通讯作者：
He M
中科院分区：
文献类型：
--
作者：
Zhang W;James PM;Ng BG;Li X;Xia B;Rong J;Asif G;Raymond K;Jones MA;Hegde M;Ju T;Cummings RD;Clarkson K;Wood T;Boerkoel CF;Freeze HH;He M
大多数先天性糖基化障碍 (CDG) 患者都存在 N-聚糖甘露糖基化的主要缺陷。我们报告了在甘露糖基化缺陷的 CDG 患者的血清、血浆和培养的皮肤成纤维细胞中发现了一系列新型 N-聚糖。我们使用 LC-MS/MS 和 MALDI-TOF-MS 分析来鉴定和定量与蛋白质核心相连的新型 N-连接四糖、血浆中的 N-四糖 (Neu5Acα2,6Galβ1,4-GlcNAcβ1,4GlcNAc)、血清糖蛋白以及 ALG1 引起的 CDG 患者的成纤维细胞裂解物 (ALG1,壳二糖基二磷酸多醇 β-甘露糖基转移酶）、PMM2（磷酸甘露糖变位酶 2）和 MPI（磷酸甘露糖异构酶）。 ALG1-CDG、PMM2-CDG 和 MPI-CDG 患者的血清、血浆或细胞裂解物中的糖蛋白比未受影响的对照组含有更多的 N-四糖。我们观察到 1 名患者接受甘露糖治疗后，MPI-CDG 血浆中的 N-四糖相对浓度下降了 80% 以上，而体外补充甘露糖的 ALG1-CDG 成纤维细胞中的 N-四糖相对浓度下降了 80% 以上。这种新型 N-四糖可以作为 ALG1-、PMM2- 或 MPI-CDG 的诊断标记物，用于筛查这 3 种常见的 CDG 亚型，这些亚型占 > 70% 的 CDG I 型患者。通过 LC-MS/MS 对其进行定量可能有助于监测甘露糖的治疗效果。这些小N-聚糖的发现也表明存在以前未认识到的N-糖基化替代途径，但其生物学意义仍有待研究。
Primary deficiencies in mannosylation of N-glycans are seen in a majority of patients with congenital disorders of glycosylation (CDG). We report the discovery of a series of novel N-glycans in sera, plasma, and cultured skin fibroblasts from patients with CDG having deficient mannosylation. We used LC-MS/MS and MALDI-TOF-MS analysis to identify and quantify a novel N-linked tetrasccharide linked to the protein core, an N-tetrasaccharide (Neu5Acα2,6Galβ1,4-GlcNAcβ1,4GlcNAc) in plasma, serum glycoproteins, and a fibroblast lysate from patients with CDG caused by ALG1 (ALG1, chitobiosyldiphosphodolichol β-mannosyltransferase), PMM2 (phosphomannomutase 2), and MPI (mannose phosphate isomerase). Glycoproteins in sera, plasma, or cell lysate from ALG1-CDG, PMM2-CDG, and MPI-CDG patients had substantially more N-tetrasaccharide than unaffected controls. We observed a >80% decline in relative concentrations of the N-tetrasaccharide in MPI-CDG plasma after mannose therapy in 1 patient and in ALG1-CDG fibroblasts in vitro supplemented with mannose. This novel N-tetrasaccharide could serve as a diagnostic marker of ALG1-, PMM2-, or MPI-CDG for screening of these 3 common CDG subtypes that comprise >70% of CDG type I patients. Its quantification by LC-MS/MS may be useful for monitoring therapeutic efficacy of mannose. The discovery of these small N-glycans also indicates the presence of an alternative pathway in N-glycosylation not recognized previously, but its biological significance remains to be studied.