Schurig Mona K, Umeh Obinna, Henze Henriette, Jung M Juliane, Gresing Lennart, Blanchard Véronique, von Maltzahn Julia, Hübner Christian A, Franzka Patricia
Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
Institute of Diagnostic Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Front Mol Neurosci. 2024 Feb 14;17:1356326. doi: 10.3389/fnmol.2024.1356326. eCollection 2024.
Guanosine diphosphate-mannose pyrophosphorylase B (GMPPB) catalyzes the conversion of mannose-1-phosphate and GTP to GDP-mannose, which is required as a mannose donor for the biosynthesis of glycan structures necessary for proper cellular functions. Mutations in GMPPB have been associated with various neuromuscular disorders such as muscular dystrophy and myasthenic syndromes. Here, we report that GMPPB protein abundance increases during brain and skeletal muscle development, which is accompanied by an increase in overall protein mannosylation. To model the human disorder in mice, we generated heterozygous GMPPB KO mice using CIRSPR/Cas9. While we were able to obtain homozygous KO mice from heterozygous matings at the blastocyst stage, homozygous KO embryos were absent beyond embryonic day E8.5, suggesting that the homozygous loss of GMPPB results in early embryonic lethality. Since patients with GMPPB loss-of-function manifest with neuromuscular disorders, we investigated the role of GMPPB . Thereby, we found that the siRNA-mediated knockdown of in either primary myoblasts or the myoblast cell line C2C12 impaired myoblast differentiation and resulted in myotube degeneration. siRNA-mediated knockdown of also impaired the neuron-like differentiation of N2A cells. Taken together, our data highlight the essential role of GMPPB during development and differentiation, especially in myogenic and neuronal cell types.
鸟苷二磷酸甘露糖焦磷酸化酶B（GMPPB）催化磷酸甘露糖和GTP转化为GDP-甘露糖，而GDP-甘露糖是细胞正常功能所需聚糖结构生物合成的甘露糖供体。GMPPB的突变与多种神经肌肉疾病有关，如肌肉萎缩症和肌无力综合征。在此，我们报告GMPPB蛋白丰度在脑和骨骼肌发育过程中增加，同时整体蛋白甘露糖基化也增加。为了在小鼠中模拟人类疾病，我们使用CRISPR/Cas9生成了杂合GMPPB基因敲除小鼠。虽然我们能够从囊胚期的杂合交配中获得纯合基因敲除小鼠，但在胚胎第8.5天之后就没有纯合基因敲除胚胎了，这表明GMPPB的纯合缺失导致早期胚胎致死。由于功能丧失的GMPPB患者表现出神经肌肉疾病，我们研究了GMPPB的作用。由此，我们发现，在原代成肌细胞或成肌细胞系C2C12中，siRNA介导的GMPPB敲低会损害成肌细胞分化并导致肌管退化。siRNA介导的GMPPB敲低也会损害N2A细胞的神经元样分化。综上所述，我们的数据突出了GMPPB在发育和分化过程中的重要作用，特别是在成肌细胞和神经元细胞类型中。
