Lin Elisa B, Meregini Steve, Zhang Zhao, Roy Avishek, Argula Tandav, Mitchell James M, Israelsen William J, Ludwig Sara, Russell Jamie, Quan Jiexia, Hildebrand Sara, Nair-Gill Evan, Beutler Bruce, SoRelle Jeffrey A
Division of Genomic and Molecular Pathology, Department of Pathology.
Division of Endocrinology, Department of Internal Medicine.
JCI Insight. 2025 Jul 22;10(14). doi: 10.1172/jci.insight.180752.
Glycans are one of the 4 major macromolecules essential for life and are the most abundant family of organic molecules. However, in contrast with DNA and RNA, glycan structures have no template; this results in limited tools to study this challenging macromolecule with a diversity of glycan structures. A central bottleneck in studying glycosylation in vivo is that inhibitors and complete KOs are lethal. In a forward genetic screen, we identified a viable, hypomorphic mutation at a conserved site in mannose phosphate isomerase (Mpi) that causes a multisystemic phenotype affecting RBCs, liver, stomach, intestines, skin, size, fat, and fluid balance in mice. The phenotype could be rescued with mannose. Analyses of glycopeptides in mice with this mutation showed a 500% increase in unoccupied N-glycan sites. This is equivalent to a "glycan knockdown," which would be useful for examining the role of glycans in biology and disease. Therefore, we report an in vivo tool to study global N-glycosylation deficiency with tissue-specific targeting and a rescue mechanism with mannose.
聚糖是生命必需的4种主要大分子之一，也是最丰富的有机分子家族。然而，与DNA和RNA不同，聚糖结构没有模板；这导致研究这种具有多种聚糖结构的挑战性大分子的工具有限。体内研究糖基化的一个核心瓶颈是抑制剂和完全基因敲除是致命的。在一项正向遗传筛选中，我们在磷酸甘露糖异构酶（Mpi）的一个保守位点发现了一个可行的、低表达突变，该突变导致一种多系统表型，影响小鼠的红细胞、肝脏、胃、肠道、皮肤、体型、脂肪和液体平衡。该表型可用甘露糖挽救。对具有这种突变的小鼠糖肽的分析表明，未占据的N-聚糖位点增加了500%。这相当于一次“聚糖敲低”，这将有助于研究聚糖在生物学和疾病中的作用。因此，我们报告了一种体内工具，用于通过组织特异性靶向研究整体N-糖基化缺陷，并利用甘露糖进行挽救机制研究。
